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044977700	summary	BACKGROUND OF THE INVENTION This invention relates to a storage structure for storing the used or spent heating elements of nuclear power plants, in particular heating elements that have been previously used and the radioactive emissions of which have been greatly reduced. The structure comprises a plurality of tubes which may be square or rectangular in cross-section and which may include one or a plurality of chambers for receiving the spent heating elements. Speaking more specifically, this invention relates to an improvement of the storage structure according to the German "Offenlegungsschrift" No. 27 30 850. In order to absorb horizontal shocks, as may occur at earthquakes, or the like, the base plates of adjacent tubes are joined together to form a storage structure less susceptible to yield to accelerating forces. In such a storage structure the individual storage tubes must be secured to it after their insertion at any given time and detached from it at any given time after their insertion. In cases where the storage tubes are permanently secured to a composite storage structure, the latter becomes so bulky that it can hardly be transported from one place to another. This calls for single smaller storage units, applicable to be connected to, and to form part of, a large composite storage structure after they have been lowered into it. This, however, also causes great difficulties, particularly if the screw connections between the individual storage tubes and the composite structure are insufficient, resulting in formation of kinks or bents in them at the occurrence of horizontal forces. The primary object of this invention consists in providing improved storage means of the aforementioned character not subject to the aforementioned limitations and drawbacks. A more specific object of this invention is to provide improved storage structures wherein the individual storage tubes are secured against the effects of horizontal forces, and the locking of the individual tubes to their support is effected exclusively by the weight of the tube when lowered, and the unlocking of the individual tubes is effected automatically when they are lifted out of the storage structure. Other objects of this invention will become more apparent as this specification proceeds. SUMMARY OF THE INVENTION According to this invention each tubular storage member is provided near the bottom thereof with a plurality of horizontal bolts, the longitudinal axes of which intersect at a common point. A plurality of support plates for said tubular member is provided at the lower end thereof. Each of said plurality of support plates is adapted to support one of said plurality of bolts and each of said plurality of support plates includes an upstanding portion. Said upstanding portion of each of said plurality of support plates is provided with an open recess including an upper relatively wide slanting entrance for the insertion of one of said plurality of bolts, and a lower, substantially circular bolt-bearing surface coaxial with one of said plurality of bolts.
	description	1. Field of the Invention The present invention relates to computer hardware performance monitoring and more particularly to an apparatus and method for detecting and forecasting resource bottlenecks. 2. Earlier Related Developments Computer systems may interconnect in complex computer networks, to share data, services and resources associated with local and/or distributed computing environments. Computer systems can include a plurality of processors, personal computers, workstations, storage servers, database servers, mainframes, network attached devices, routers, firewalls, and other devices, all interconnected by wired or wireless interconnection networks. A critical resource is a part of the system upon which the overall performance of the system relies significantly. As such, when a critical resource is operated in a failed, saturated, or near-saturation regime, it may become a resource bottleneck to the efficient operation of the system. To maintain or optimize performance, it is important to detect and locate resource bottlenecks either when they occur or in a predictive manner before they take place in order to take corrective or preventative actions. Methods relating to bottleneck detection are related generally to the field of capacity management. In one such method, a device, such as a processor, is measured and compared to whether it is operating near capacity by comparing the value of its utilization to a known maximum value threshold. Other methods expand on this approach to allow different bottleneck detection strategies based on simple threshold comparisons such as where bottlenecks are declared when one or more subsystems are operating near saturation even though other subsystems are under utilized. Examples of bottleneck methods are illustrated in U.S. Pat. Nos. 6,557,035, 6,470,464 and 6,457,143, all of which are incorporated by reference herein in their entirety. A problem arises in that some methods rely on known maximum values for resource utilization that may not be available such as where the throughput of a large scale storage system is dependent on the kinds of data that are stored on the system, the status of the physical storage medium, and/or its internal interconnect network as examples. In this instance, the maximum throughput may be time variant and standard bottleneck detection would fail. Accordingly, there is a desire to provide a resource bottleneck detection, prevention and/or elimination method and system that is simple, and robust. In accordance with one embodiment, a method of detecting and forecasting resource bottlenecks of a computer system is provided having a first step of monitoring with successive measurements a utilization parameter of a system resource. Steps of computing a change parameter by comparing the differences between successive measurements of the utilization parameter and comparing the change parameter to a threshold change parameter are then provided. A step of reporting a resource bottleneck if the change parameter exceeds the threshold change parameter is then provided. In accordance with another embodiment, a computer program product is provided having a computer useable medium having computer readable code means embodied thereon for causing a computer to execute a method for detecting and forecasting resource bottlenecks of a computer system. The computer readable code means in the computer program product has computer readable program code means for causing a computer to monitor with successive measurements a utilization parameter of a system resource. Computer readable program code means for causing a computer to compute a change parameter by comparing the differences between successive measurements of the utilization parameter and computer readable program code means for causing a computer to compare the change parameter to a threshold change parameter is also provided. Computer readable program code means for causing a computer to report a resource bottleneck if the change parameter exceeds the threshold change parameter is then provided. In accordance with another embodiment, a data processing system is provided having a processor and a program code executed on the processor for detecting and forecasting resource bottlenecks, the program code including code for: monitoring with successive measurements a utilization parameter of a system resource; computing a change parameter by comparing the differences between successive measurements of the utilization parameter; comparing the change parameter to a threshold change parameter; and predicting a resource bottleneck if the change parameter exceeds the threshold change parameter. Referring to FIG. 1, there is shown a schematic view of a computer system network 10 incorporating features of an exemplary embodiment of the present invention. Referring also to FIG. 2, there is shown a block diagram of the hardware resources of server 14 incorporating features of the exemplary embodiment. Computer system 10 can include a plurality of processors, personal computers, workstations, storage servers, database servers, mainframes, network attached devices, routers, firewalls, and other devices, all interconnected by wired or wireless interconnection networks. Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. Computer System Network 10 may include a plurality of client machines 12 and a server machine 14. Machines 12 and 14 are connected to a local area network (LAN) 18. Network 10 is depicted in a ring topology. In alternate embodiments, the method and system of the present invention may be applicable to other network topologies and configurations. Additionally, the method and system of the present invention may be applicable to wide area networks (WANs), intranets, the internet, as well as local area networks. Server 14 may include a central processing unit (CPU) 20. In alternate embodiments, server 14 may include multiple CPUs. Server 14 also includes memory 22. CPU 20 may access memory 22 to perform computing tasks. Server 14 may include peripheral devices or resources necessary to perform its server functions. The resources may include a LAN adapter 24 and a disk or memory storage device 26 that may be connected to CPU 20 and memory 22 by a I/O bus 28. In alternate embodiments, server 14 may include multiple LAN adapters 24 and multiple disks 26. Server 14 may include peripheral devices such as a printer 30, a display 32, a keyboard 34, and a pointing device 36, all of which may be connected with CPU 20 and memory 22 by IO bus 28. The resources that may be applicable to the method and system of the present invention may be, for example, CPU 20, memory 22, LAN adaptor 24, and disk or memory storage 26. In alternate embodiments, other resources, either hardware resources, software resources or otherwise may be applicable to the method and system of the present invention. Parameters associated with utilization of resources such as CPU 20, memory 22, LAN adaptor 24, and disk 26, may be monitored by the server 14 with performance monitoring tool. In alternate embodiments, different parameters may be measured on different hardware or software components on different tools or platforms. Examples of monitored parameters may include CPU utilization, memory utilization, either logical disk queue depth or disk utilization, LAN bytes per second (LAN byte throughput) and LAN packets per second (LAN packet throughput). A rules-based methodology according to the present invention may be applied for detecting and forecasting resource bottlenecks and generating or executing corrective action recommendations on how to circumvent or remedy the identified bottlenecks with upgrades. Referring now to FIG. 3, there is shown a high level flow diagram of a method for detecting and forecasting resource bottlenecks according to the present invention. The method is based on detecting bottlenecks from the temporal evolution of the utilization of a resource rather than its instantaneous value. In the exemplary embodiments, rather than simply comparing values of utilization to thresholds, the methods compare the differences between values measured in successive time intervals to thresholds. In these methods, the maximum utilization value of the resource may not be used or know. As such, bottlenecks may be detected in portions of the system that are not being measured directly, where the bottleneck prevents the measured resource from being fully utilized. Measurements are taken within intervals every S seconds on the utilization of a resource where S may be constant or variable. The measurements may be taken at regular intervals or at varying intervals and adjusted or normalized accordingly. These measurements may be the value of counters, or may be for example CPU utilization where an actual percentage or percentages of utilization may be available. Here, the machine may indicate that in a period of S seconds, the CPU utilization was some number or some percent of the maximum. Alternately, the measurements or counters may indicate, for example, that some number of I/O operations occurred during the interval of duration S where, for example, it may not be known what percentage of I/O bandwidth had actually been utilized. In any event, even if, for example, the indicated CPU utilization is low compared to the maximum, bottlenecks elsewhere in the system may be limiting throughput. When utilization somewhere in the system approaches a level where there is a bottleneck, an increasing percentage of intervals of duration S approach maximum available load. This can occur if even, for example, the measured resource does not approach full utilization. Such occurrences may be detected by observing certain properties of the evolution with time of the utilization observations. Such observation may be accomplished by observing properties of the changes over time of the utilization measurements and then exploiting these observations. Timeline 40 has time intervals of length T. Each interval T has n periods of length S. In each interval, measurements 42 are taken relating to parameters of one or more resource. These measurements are evaluated in function blocks 44a, 44b, . . . 44k and the resulting functions or values may be stored in storage block 48. Comparisons such as, for example, differences between functions over time may be performed in block 50. Comparisons may be stored in block 54 for subsequent use. A decision engine in block 58 determines if the system is acceptable or if, for example, bottlenecks are detected or predicted to initiate an alert or corrective action 60. Referring also to FIG. 4, there is shown an exemplary implementation of a method for detecting and forecasting resource bottlenecks. U(I) may denote, for example, the utilization during the ith interval, i=1,2, . . . , n of a resource. In one implementation, for each interval of length T, the associated periods of length S may be divided into R classes, r=1,2, . . . , R where the rth class contains approximately n/R intervals where the utilization was larger than that for the (r−1) class. U(r,i) may be the average utilization for the rth class in period i. Let Delta(r,i)=U(r,i+1)−U(r,i). If Delta(r,i)<=Delta(r−1,1), and Delta (r,i)>0, for r=R, R−1, . . . R−Q, for a chosen value of Q, the system alerts the administrator. In another implementation, rather than computing the difference of the average utilization Avdel(i), the standard deviation Dev(i) is computed for the utilization measurements in the periods of length S in the ith interval of length T. The system alerts the administrator if U(i+1) is greater than U(i), and Dev(i)>Dev(i+1). As saturation is approached, some work may arrive in a period of length S, but not be completed until the following period resulting in a spillover effect. As the load increases, this spillover effect becomes manifest, as an increase of the fraction of time in which the system experiences heavier loads, as processor capacity is approached in periods already heavily loaded. The occurrence is detected as follows. Med(i) represents the median load for the periods of length S in the ith interval of length T. The administrator is alerted if Med(i) is smaller than U(i), but Med(i+1) is greater than U(i+1). This embodiment is termed the median-crossing detector. Measurements taken from the system may possess short term variations that could unnecessarily trigger alarms. In order to improve the bottleneck detector's resistance to noise, a threshold can be added to the comparisons that are judged to be exposed to such problems. Suitable values for the thresholds can be manually or automatically set through empirical means and later modified by the administrator through a user interface. An example is extended from an embodiment where the thresholds states that we will alert the administrator if U(i+1) exceeds the value of U(i) by at least a threshold tsubu and if Dev(i+1) is smaller than Dev(i) by at least tsubd. Values for tsubu and tsubd may be learned or modified by employing an iterative process of modifying the thresholds as transient false alarms and undetected problems present themselves. Another method of improving the quality of the alarms is to employ data from more than two intervals of length T; this can be done independently of whether thresholds are being employed. One method of extending any of the embodiments described is to use information from additional periods and to delay triggering the alarm until a problem is detected in M out of the last N time intervals (M<=N). A method in which both thresholds and multiple time intervals are employed is demonstrated by modifying the median-crossing detector previously described. An alert is issued to the administrator if in the last N intervals, a time interval i is located for which Med(i)<U(i)−ti and a later time interval j for which Med(j)>U(j)+tj. It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.
050680803	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is incorporated into a plant monitoring and display selection computer 10 such as described in U.S. Pat. Nos. 4,803,039 and 4,815,014 and illustrated in FIG. 1. The plant operator 12 through an interactive input unit 14, such as a keyboard, can provide appropriate inputs to the computer 10 to initialize and initiate the monitor process as the plant 16 is started moving from one state to another state in accordance with a prescribed printed procedure or sequence or preplanned sequence of operations available to the operator 12 or in accordance with an unwritten but preplanned operation sequence previously learned or developed by the operator or system designer. The operator has the capability of monitoring the sequence of events that occur during the desired change of state via a display 18. The present invention will allow the operator to proceed with the state change procedure using other input units such as a plant control board while the computer 10 automatically monitors plant instrumentation, processes the instrumentation data to detect successive steps in the plant change of state, compares the observed steps in the plant change with the prescribed sequence and, via the display 18 and other alerting devices such as an audible annunciator bring the operator's 12 attention to any deviations from the prescribed sequence. In order for the computer 10 to monitor the changes which should be occurring in the plant 16, the prescribed procedure that the operator is to follow must be resolved into a sequence of changes in plant state that occur. Each step in the sequence of changes in state must then be reviewed and analyzed to ensure that the available plant instrumentation is adequate to detect the change in state. Finally, the several changes in state are divided into four different categories. These categories are: initial conditions which must be satisfied before the evolution from one state to another state can be started; sequential conditions which are the progressive plant states which are to be encountered in the transition toward the final intended plant state; constraining conditions which are enforced during the evolution through the successive plant states and are intended to keep the change of state within prescribed boundaries; and final conditions which must be satisfied before the evolution to the desired state can be determined as completed. Of the above four conditions, initial conditions and final conditions can be treated in the same manner. Once the categories and inputs are determined, the designer develops a flowchart from which a program can be produced in a commonly used high level language such as Fortran. By dividing the individual changes in state into the categories of initial, sequential, constraining and final conditions the organization of the final computer program, can be as illustrated in FIG. 2. The present invention is initiated 30 when the operator begins the transition or evolution from a current plant state to some desired future plant state. As previously mentioned before the state changes can be started initial conditions checks 32 must be performed. Because modern digital computers are extremely fast it is possible, and sometimes desirable, to have the computer perform all of the initial condition checks in a continuously executing loop as depicted in FIG. 2. In such a loop whenever one or more of the initial condition checks 32 are satisfied a bypass path is taken which bypasses the monitoring and condition checking necessary for that particular condition check. If all the conditions are not satisfied initial condition displays 34 are produced and a loopback path 36 is taken until all initial condition checks are satisfied. When all of the initial condition checks 32 are satisfied, a multi-tasking operation is commenced in which sequential condition checks 38 and constraining condition checks 48 are performed concurrently. As each one of the sequential condition checks is satisfied a bypass path around the condition check can also be taken. When the sequential condition checks are not satisfied sequential condition displays 42 are produced for operator guidance. The sequential condition checks are continuously executed by execution control following the loopback path 46 which causes all checks in the system not bypassed to be periodically re-executed. As an alternative, in the sequential condition checks, when a particular condition must be satisfied before further progress in the state change can be accomplished a loopback path on that condition can be provided. In parallel with the sequential condition checks 38, constraining checks 48 are performed. Once again when the constraining checks are properly satisfied a bypass path within the group of checks can be followed. When the constraining condition checks 48 are not satisfied a loopback path 52 for constraints which must be satisfied can be taken. Whenever the condition checks for constraints are not satisfied displays 54 devoted to informing the operator about unsatisfied constraints are produced. Prior to arrival at the desired state, final condition checks 56, which are conceptually the same as initial condition checks 32, are performed and appropriate final condition deficiency displays 58 are provided if necessary. Once again if the final checks are not satisfied a loopback path 60 is taken until all are satisfied. Initial conditions and final conditions are, by their nature, static and once verified as being satisfied need not be considered again. These types of conditions can be thought of as parallel rather than sequential conditions. Testing a particular initial or final condition consists simply in monitoring those plant parameters that together define the condition, comparing the parameter values to preset standards, which may be allowable ranges or specified valve or breaker positions, and determining whether the standards are met. If or when the tested condition is shown to be satisfactory, the verification process passes to the next condition in the programmed sequence or begins bypassing the check in a continuously executing loop. A generic flowchart building block that can be used in constructing the initial condition check portion of a system is shown in FIG. 3. This basic building block includes a step 70 which determines whether a bypass flag for this particular condition is set. If it is, the entire set of logic operations associated with this condition is bypassed. As a result, this flag allows an initial condition loop to only execute the logic for those conditions that are not satisfied. If the bypass condition is not set, the sensor signals, etc., for the condition are monitored 72 followed by a determination 74 as to whether the particular condition is satisfied. If the condition is not satisfied a detailed diagnostic display 76 is provided to the operator which will indicate the deficiency in satisfying the condition and the action necessary to correct the deficiency, along with an auditory tone if desired, and a branch is taken around the remainder of the logic in the block. This display should be designed to alert the operator by grabbing the operator's attention and could replace a display that would normally continuously be before the operator. The alerting of the operator should be an active rather than a passive operation. If the condition is satisfied a display 78 is produced which provides condition satisfaction confirmation to the operator and the bypass flag for this condition is set 80. Because the system is intended to minimally intrusive, this confirmation should not produce an audible tone or flashing display which would grab the operator's attention but is preferably something such as a single line textual confirmation line on a display that is otherwise used by the operator for a different purpose, is within the operator's field of vision and is generally continually before the operator. The confirmation should disappear after a brief period sufficient to allow the operator to check the confirmation if desired. This confirmation should be passive rather than active. Problems in determining whether initial conditions are satisfied often arise from the incompleteness of the computer instrumentation data base. Written procedures covering nearly routine operations frequently contain requirements that the alignment of certain plant systems be verified before a transition in plant state is started. Verification of system alignment may translate into checking the positions of large numbers of valves and breakers, only a few of which are instrumented for transmission of information to the main control room/plant computer 10. Because of the infrequency with which such information is needed, as implied by the definition of nearly routine operations, providing a sufficient set of remote reading plant instrumentation would not be cost effective and, as a result, functions that could be done by a computer will remain in the province of a human. In this situation where the signals, etc., are not available to the computer 10, operator response, when appropriate, to high level questions such as "Has checklist 1 been completed?", displayed periodically by the computer 10, would be desirable for documentation purposes, but would also tend to make the system more obtrusive. However, with a modest amount of operator interaction, verification that all prescribed initial conditions are satisfied by having the operator input data can at least be documented by the present system. In such situations, the initial condition basic logic building block would take the form of FIG. 4. In this basic building block, once the condition bypass flag is checked 90 the system immediately provides a display 92 to the operator which informs the operator of the condition that must be satisfied and requests positive operator response that the condition has been satisfied. Once again, this display should be designed to alert and get the operator's attention, and could be flashing or accompanied by an auditory signal. Once this display has been produced the system enters a timeout period which is calculated to provide the operator with sufficient time to provide the necessary positive response. If no positive response is produced a timed interrupt 94 will cause the process to exit this block without setting the condition bypass flag, so that the next time through the initial condition loop this display including the response request will be provided to the operator again. If the operator does provide a positive response, the exit from the interrupt 94 produces a display 96 which confirms the operators positive response and then sets 98 the condition bypass flag, so that the next time through the initial conditions loop this logic will be bypassed. As can be seen FIG. 5 is a combination of FIGS. 3 and 4 with a return loop which causes a return, when all the bypass flags are not set 100, to a timed delay or timeout 102 which should be set for a period which will allow the conditions in the plant to change sufficiently such that another cycle of initial condition monitoring is appropriate. Success of the computer based operator support system of the present invention hinges on the ability of the system to pace itself through the prespecified sequence of plant state changes as the sequence unfolds. Steps such as block 100 in FIG. 5 and appropriate time-out periods allows the event monitoring and condition checking flow and the operations to be properly coordinated. Since the prime concern of the plant operators in the nearly routine operations of interest here are transitions in plant state, the information necessary to monitor the transition process is usually available in the main control room, either as direct instrumentation readout or by voice communication from remote local work areas. In principle, any information available in the control room can be made available in the data base of a modern in-plant computer 10. At worst, data currently transmitted verbally from a remote work area (the turbine building or the chemistry lab, for example) can be input by the local operator with a few keystrokes at a workstation terminal at the completion of a task. A basic flowchart building block for tracking sequential conditions (the state transitions) is shown in FIG. 6. This basic building block first includes a step which monitors 110 the plant instrumentation. This step includes not only the typical monitoring of plant sensors but also the combining of sensor signals and other information, such as the results of chemical analysis from the chemistry lab to determine whether the state has been reached. Once the monitoring step is completed the determination 112 as to whether the state has been reached is performed. If the state has not been reached, the system produces a detailed alerting type diagnostic display for the operator explaining what components of the state have not been reached along with any graphics 116 which would aid the operator in moving the plant toward the desired state. If the state is not attained then a loopback to monitor 110 the state indicators is performed. Although not shown, it is possible to provide a time out period in the loop back path, so that the plant will have time to respond to any changes made by the plant operator in response to the alerting display 114 before the state indicators are again monitored. By providing the loopback to monitor when the condition is not satisfied, the system can insure that each condition is satisfied before the next sequential condition is tested. If the state is attained an appropriate display 118 can be provided to the operator along with associated graphics which will confirm to the operator 12 that the state has indeed been attained. The step 112 which determines whether the state has been attained can be much more complicated than it appears from FIG. 6. It may be necessary for the system designer to break the operation in step 112 into a number of condition checking steps before the ultimate determination can be reached. These conditions can be sequential as illustrated in FIG. 7 or even parallel like the initial conditions. An example of a situation where the step 112 has been broken down into a series of more simplified sequential condition checking steps is illustrated in FIG. 7. In the example of FIG. 7 (as required in block 110) temperature and pressure are first monitored 130 and a trend plot is provided to the operator. Next the system determines, although not explicitly shown as a decision block, whether all of the conditions in this segment of the checking operation have been satisfied by checking a main bypass flag and, if so, a main bypass path is followed. If not, the computer 10 determines 134 whether the pressure satisfies a particular condition. If the pressure condition is not satisfied the flow is returned to the monitoring step 130. By requiring return to the monitoring step the condition of block 134 must be satisfied before the next sequential condition is satisfied. If satisfied the system does a check 136 on the position of a certain set of valves and if they are not all open an appropriate alerting type display 138 is provided to the operator followed by a loopback to the monitoring step 130. Prior to block 136 a bypass flag check, as in step 70, is implied for routing around step 136 when it has been satisfied. If the valves are all open the system provides an appropriate high level display 140 to the operator, sets 142 a first inner bypass flag so that the bypass check implied between steps 134 and 136 will cause step 136 to be bypassed if this flag is set. To convert a step such as 136 from a sequential condition to a parallel condition, the loopback path could instead be connected to enter the first inner bypass path after producing the appropriate display 138. The process then determines if the second inner bypass flag is also set 144, if so the main bypass flag is set so that the system will bypass the entire logic block. Next, after impliedly checking the second inner bypass flag, the system performs a purge check 146, provides an appropriate alerting display 148 if the purge is not secured and loops back for another monitor cycle 130. If the purge is secured an appropriate display 150 is provided to the operator followed by setting 152 the second inner bypass flag and checking 154 on whether the first inner bypass flag is set and setting the main bypass flag if so, so that the next time through this block the main or second inner bypasses can be taken as appropriate. At the end of such a sequence of logic blocks a check (not shown), as in step 100, is made to confirm if all bypass flags have been set otherwise a loopback over the loopback path is performed. This allows the sequential condition loop to be cyclically performed until all checks are completed. The sequence of steps of FIG. 7 illustrates the loop back/bypass logic that can be used during a prolonged, continuous change in plant state, in this case heat up and pressurization of the primary system of a pressurized water reactor. Note that while there is an implied (and real) flow of time from left to right, there is no explicit indication of time in the diagram. The evolution of plant states progresses at whatever rate the operators can achieve and the plant itself can safely tolerate. Under the generic heading of constraining conditions all of the precautions, limitations, notes and so on that channel sequences of changes in plant state along safe routes are considered. Constraining conditions are seen to be passive unless violated; hence, there is no need to provide any information to the plant operator, unless, again, a violation has occurred or is impending. In that event the system must alert the responsible operator, indicate to him what the problem is by text or graphics, as appropriate, and secure his acknowledgment that he has been alerted. A typical flowchart basic building block for automatic constraint monitoring is set forth in FIG. 8. The monitoring process for constraint checking is simple and straightforward. Applicable constraints are almost universally spelled out in the written procedures provided to the plant operators and, as a result, the information needed to insure compliance with the constraints is available in the control room and, by implication, in a plant computer's database. The basic building block for automatic constraint monitoring illustrated in FIG. 8 further illustrates the feature of the present invention of being unobtrusive to the operator which is accomplished by only providing the constraint violation display to the operator and alerting him periodically and not continuously. The block provides this feature by bypassing the monitor and display logic if the bypass timer for this constraint is running. If the timer is not running the block monitors the constraint parameters 162 and determines 164 if the constraint is satisfied. If the constraint is not satisfied a timed interrupt block 166 is entered which produces constraint violation graphics 168 which will alert the operator (grab his attention) and appropriate diagnostics 170 (along with an audible signal, if desired) and waits for the operator to acknowledge the constraint violation. When the constraint violation is acknowledged the logic continues through the step of setting 172 the bypass timer. The time out value of the bypass timer should be set at a fraction of the time it takes for the constraint violation to begin causing serious damage or expense. Because the constraints are applicable throughout the entire operation, whenever the bypass timer is not running the constraints are monitored and tested. The constraint monitoring logic diagrams are organized as stacks of basic building blocks assembled to form continuous loops as illustrated in FIG. 9. All applicable constraining conditions are to be tested in each pass through a loop if not bypassed by a timer being set. The monitoring and checking loop consists of checking 180 whether the n-th bypass timer is running, if not monitoring 182 fuel flow, determining 184 if the fuel flow is running at a certain value, determining 186 whether the n+1th bypass timer is running, if not monitoring 188 the flue gas temperature, determining 190 whether the flue gas temperature is a certain value and then returning through a time out block 192 to execute the loop again. The timeout block 192 time out period could be set at, for example, 30 seconds. If the conditions associated with monitoring the fuel flow are not satisfied the system produces a timed interrupt 194 along with appropriate graphics 196 and diagnostics 198 and awaits operator acknowledgement before continuing to start 200 the respective bypass timer. The failure to satisfy the fuel gas constraints provides a similar sequence 202-208. As can be seen the monitoring and checking loop itself is interrupted only by detection of an existing or impending violation and only until the operator's acknowledgment is received. On receiving the operator's acknowledgement a dedicated bypass timer is set. Thereafter, testing of that particular constraint is bypassed on successive passes through the loop until the bypass has timed out to avoid distracting the operator with a repetitive message of which he is already aware. Passes through a loop are to be initiated periodically, perhaps every few seconds or every minute during a nearly routine operation. Achieving specified plant states as identified in stepping through the sequential conditions logic can be used to trigger adding or deleting individual constraint monitoring building blocks. This can be accomplished by requiring that a sequential condition be met before the constraint is tested. That is the output of block 112 could logically flow to a constraint block. In FIG. 10, the loops 222-224 represent constraint block executions while the loop 226 represents a sequential condition block conditionally calling constraint blocks 222 and 224. Since constraints tend to be in force through much or all of a given evolution and since no display generation is needed or wanted under normal circumstances, execution of a loop can be nearly instantaneous with a modern computer, it appears to be practical to, in effect, lift the constraint monitoring task out of the time domain in which the sequential conditions exist and produce a combination of sequential condition executions and constraint executions as illustrated in FIG. 10. The alerting and confirmation displays produced by the present invention can be created by those of ordinary skill in the art. Preferably text is used to inform the operator that a given component, parameter or system is or is not in the correct state. It should be noted that according to the objectives of the present invention it is quite possible that an operator would never look at the text that states that all is in order, and so such displays should appear for short intervals of time and then disappear. In some cases, this textual information alone will be sufficient. However, particularly in cases where something is amiss, additional information should be presented to the operator and should be graphic in nature. The graphic displays may appear in several forms. Graphic depictions of functional processes portray to the operator the purpose of a system, irrespective of the exact physical configuration. Graphic depictions of physical processes are true to the piping and instrumentation layouts of the plant. Each of these graphic forms presents a different viewpoint to the operator, a viewpoint which the operator may require at a particular stage of the plant maneuver. Appropriate selection of the type of functional graphics can be specified by the system designer. Other graphic displays which may prove to be useful are parameter versus time displays and trajectory displays in which one parameter, pressure, for example, is plotted against another, such as temperature. These types of displays are particularly useful during startup and shutdown activities for a power plant, since it is very desirable for parameters to follow either time-dependent trajectories or to follow other parameters during these events. An example of the workings of the automatic system of the present invention for monitoring the execution of procedures can be found by examining how the system would track the process of taking a large nuclear power reactor critical by control bank withdrawal. The operator's actions, as defined by the pertinent written procedure, consist generally of: 1) Selecting the size of the next movement of the control bank. 2) Making the decided upon adjustment in control bank position, concurrently closely monitoring the rate of change of source range count rate and control rod positions to insure that controlling plant technical specifications are satisfied. 3) Observing the resulting time dependent change in source range count rate following the control bank movement. 4) Recording the final stable count rate, assuming the count rate stabilizes, and using the reading of final count rate to compute the value of a parameter called the inverse count rate ratio (i.e. the ratio of a reference count rate taken earlier, divided by the current stabilized count rate) and plotting the value of the ratio against bank position on a two dimensional graph. (The ratio plot has the well known property that successive points, corresponding to progressively farther withdrawn bank positions, will trend steadily toward the horizontal axis and will fall precisely on the horizontal axis, i.e. the ratio=0.0, when criticality is established). 5) Evaluating the most recent few points on the ratio plot, judging at what control bank position criticality will occur and returning to step 1. At some point in the process the count rate will fail to stabilize following a control bank movement and will instead tend to increase exponentially, indicating that the core is now slightly supercritical. When this condition is clearly identified the operator should insert the control bank enough to stop the exponential rise in count rate, and that part of the procedure will have been completed. A computer programmer's flow chart for the part of the procedure execution monitor system dedicated to monitoring the particular operation described above is shown in FIGS. 11A-11C. This figure also shows what would be considered appropriate displays for alerting the operator concerning deviations from the procedure and confirming normal operations. Displays 238 and 264 which include imperative statements are examples of alerting type displays while displays 254 and 298 are examples of confirmatory displays. Note that the monitor operates completely automatically with no need for input from the human operator. Progress through the flow chart and selection of displays to be generated is controlled by three internal triggers: a) detection of control bank movement; b) determination that count rate is rising exponentially; and c) determination that count rate is no longer changing. Implied in the flow chart of FIGS. 11A-11C, but not explicitly shown, is the potential for segregating the constraining condition type checks made as control rod withdrawal proceeds into a separate concurrently running computer task. Thus, by well known methods such checks as "Are the shutdown rods fully withdrawn?" or "Are step counters and RPI (rod position indicators) in agreement?" could be executed by a separate, periodically executed computer task running in parallel with the sequential control rod withdrawal process monitor rather than having these checks called by the main process flow as in FIG. 10. Using a monitoring system for the process as described above provides valuable information efficiently to the operator and potential errors in procedure execution (for example, withdrawal of a control bank too many steps, leading to an unacceptably high startup rate) are detected without imposing on or interfering with the operator's normal actions. A more detailed procedure and the flowchart which could result therefrom is attached as the microfiche appendix. In a number of complex processing facilities, operations such as plant startup, for example, are carried out in part under the control of operators at the main control board in the central control room and in part under the control of operators at local control panels dispersed throughout the facility. Frequently, information relating to the start of various plant systems is available at one or another of the local control panels but not in the central control room. It is evident by simple extrapolation of the principles described above that the local control panels could be equipped with local, dedicated computers that are programmed to monitor locally available information and to track the progress of the execution of procedures involving plant systems controlled from the respective control panels. Single communications links coupling the individual local computers to the main central computer in the control room would then be used to convey to the central computer information regarding the completion of locally executed procedures that are nested in encompassing procedures executed from the main control room. Thus, the execution of procedures or operations involving both central and local control of systems can be comprehensively monitored without imposing excessive input requirements on the central monitoring computer. Alternatively, the respective local computers could interact with a data highway system to pass relevant information to the central computer. As can be seen from the above description the conventional written procedures provided to plant operators to guide them, as necessary, in carrying out such nearly routine operations also serve as effective guides in developing the high level logic flowcharts that facilitate the transition from certain nominally cognitive human tasks to rule-based computer tasks. Resolution of the written procedures by a specialist in plant operations into initial conditions, sequential conditions, constraining conditions and final conditions, all recognizable by the computer, follows straightforwardly. The many features and advantages of the invention are apparent from the detailed specification and thus it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalence may be resorted to, falling within the scope of the invention.
055725627	summary	TECHNICAL FIELD OF THE INVENTION The present invention relates to techniques for manufacturing semiconductor devices and, more particularly, to techniques for forming patterned features on a semiconductor device. BACKGROUND OF THE INVENTION Photolithography is a common technique employed in the manufacture of semiconductor devices. Typically, a semiconductor wafer is coated with a layer of light sensitive resist material (photoresist). Using a patterned mask or reticle, the wafer is exposed to projected light from an illumination source, typically actinic light, which manifests a photochemical effect on the photoresist, which is ultimately (typically) chemically etched away, leaving a pattern of photoresist "lines" on the wafer corresponding to the pattern on the mask or reticle. The patterned photoresist on the wafer is also referred to as a mask, and the pattern in the photoresist mask replicates the pattern on the image mask (or reticle). As used in the main, hereinafter, with respect to semiconductor lithography, the term "upstream" means towards the illumination or radiation source, and "downstream" means away from the illumination source (or, towards the wafer). For example, a lens in the illumination path of photolithographic apparatus has an upstream side facing the illumination source and a downstream side facing away from the illumination source. FIG. 1 shows a simplified prior-art photolithographic apparatus 110 for exposing a semiconductor wafer (W), more particularly a coating thereon (e.g., photoresist), to light. An optical path is defined from left to right in FIG. 1, as viewed. Prior to exposure, the semiconductor wafer (W) typically receives on its front surface a layer of photoreactive material (not shown), such as photoresist. A light source 112 emits actinic light, and may be backed up by a reflector 114. Light emitted by the light source typically passes through a uniformizer 116, such as a "fly's eye" lens or a light pipe. Light exiting the uniformizer 116 is represented by rays 118a, 118b, and 118c, and passes through a condenser lens 120. The ray 118b represents the optical axis of the photolithographic apparatus. The light source 112, reflector 114, uniformizer 116 and condenser lens 120 form what is termed an "illuminator" which is often detachable as a unit from the photolithographic apparatus. An image mask 122 ("M") is disposed "downstream" of the condenser lens 120, at the focal plane (point) thereof. One type of image mask used in the photolithography process is a chromed glass or quartz plate bearing the pattern to be projected onto the photoresist layer. Light is projected through the image mask, and those areas of the image mask which are not chromed allow the light to expose the photoresist, while those areas of the image mask which are chromed prevent the light from exposing the photoresist. The exposed areas of the photoresist typically resist chemical etching, while the unexposed areas can readily be removed, leaving a pattern of photoresist on the surface of the wafer. Further downstream along the light path, the rays diverge from the mask 122, and pass through a "taking" (imaging) lens 124. Because of its imaging function, the taking lens 124 must be of relatively high quality as compared with the condenser lens 120. The mask 122 is disposed at a common focal point of the two lenses 120 and 124. A semiconductor wafer (W) is disposed at the "downstream" focal plane, or image plane, of the taking lens 124. Those areas of the mask (or reticle) which are not chromed allow the light to expose a photoreactive layer (e.g., photoresist) on the surface of the wafer (W), while those areas of the mask which are chromed (or otherwise opaquely patterned) prevent the light from exposing the photo-reactive layer. The photoreactive layer is typically a photoresist material. The exposed areas of the photoresist resist chemical etching and, in subsequent processing, are used to form defined features on the wafer (such as on a layer of polysilicon underling the photoresist). The resist materials used in photolithography are typically organic. Typical resist materials for visible light photolithography include mixtures of a casting solvent, such as ethyl lactate, and novolac resin (diazoquinone). Inasmuch as the light passing through the image mask (reticle) has an inherent characteristic that induces photochemical activity in the photoresist material, such radiation (e.g., light) is termed "actinic". In current photolithographic apparatus, light having at least a substantial visible content is typically employed. Visible light has a frequency on the order of 10.sup.15 Hz (Hertz), and a wavelength on the order of 10.sup.-6 -10.sup.-7 meters. The following terms are well established: 1 .mu.m (micrometer) is 10.sup.-6 meters; 1 nm (nanometer) is 10.sup.-9 meters; and 1 .ANG. (Angstrom) is 10.sup.- meters. Among the problems encountered in photolithography are non-uniformity of source illumination and point-to-point reflectivity variations of photoresist films. Both of these features of current photolithography impose undesirable constraints on further miniaturization of integrated circuits. Small and uniformly sized features are, quite evidently, the object of prolonged endeavor in the field of integrated circuit design. Generally, smaller is faster, and the smaller the features that can be reliably fabricated, the more complex the integrated circuit can be. With regard to uniformity of source illumination, attention is directed to commonly-owned U.S. Pat. No. 5,055,871, issued to Pasch. As noted in that patent, non-uniformities in the illuminating source will result in non-uniformities of critical dimensions (cd) of features (e.g., lines) formed on the semiconductor device, and the illumination uniformity of photolithographic apparatus will often set a limit to how small a feature can be formed. There usually being a small "error budget" associated with any integrated circuit design, even small variations in illumination intensity can be anathema to the design goals. with regard to reflectivity of photoresist films, it has been observed that minor thickness variations in a photoresist film will cause pronounced local variations in how efficiently the illuminating light is absorbed (actinically) by the photoresist film, which consequently can adversely affect the uniformity of critical dimensions (cd) of features (such as polysilicon lines or gates) sought to be formed in a layer underlying the photoresist. This problem is addressed in commonly-owned, copending U.S. patent application Ser. No. 07/906,902, filed Jun. 29, 1992 by Michael D. Rostoker, which discussed techniques for applying a substantially uniform thickness layer of photoresist, and which is incorporated by reference herein. Another, more serious problem with photolithography is one of its inherent resolution. The cd's of the smallest features of today's densest integrated circuits are already at sub-micron level (a "micron" or ".mu.m" is one millionth of a meter). Such features are only slightly larger than a single wavelength of visible light, severely pushing the limits of the ability of visible light techniques to resolve those features. As integrated circuit features become smaller, the demand for more nearly "perfect" optical components increases. At some point, however, such optics become impractical and inordinately expensive, or even impossible to produce. Although the resolving power of light, vis-a-vis submicron semiconductor features is being stretched to its limit, the ability to etch (wet, dry, chemical, plasma) features on a semiconductor wafer is not limited by wavelength. As is well known, ultraviolet light (UV) is slightly higher (in frequency) on the electromagnetic spectrum than visible light. Typically, ultraviolet light has a frequency on the order of 10.sup.15 -10.sup.17 Hz, and has a wavelength on the order of 10.sup.-7 -10.sup.-8 meters. Ultraviolet light is known to be actinic, for example with respect to skin pigmentation. Due to its shorter (than visible light) wavelength, ultraviolet light would seem to hold promise for increased resolution in integrated circuit photolithography. However, it is difficult to find reliable, fluent sources of UV (typically vacuum UV) light. Further, the performance of present day optics begins to degrade substantially at around 190 nm (1.9.times.10.sup.-7 meters; which is towards the top of the visible light spectrum), and is not well suited for focusing UV light. In contrast to visible light, X-rays have a much shorter wavelength. Typically, X-rays have a frequency on the order of 10.sup.17 -10.sup.20 Hz, and have a wavelength on the order of 10.sup.-8 -10.sup.-11 meters. Evidently, due to their shorter wavelength, X-rays have the inherent capability of providing better resolution than visible light. However, as with UV sources, there are some problems with obtaining reliable emission sources that exhibit good fluence. The best (most intense) X-ray sources (e.g., X-ray tubes) produce X-rays in the range of 1-10 .ANG. in wavelength, with a nominal output spectrum between 2 .ANG. and 6 .ANG. in wavelength. Gamma-rays exhibit an even shorter wavelength than X-rays. Typically, Gamma-rays have a frequency on the order of 10.sup.19 -10.sup.22 Hz, and have a wavelength on the order of 10.sup.-10 -10.sup.-12 meters. Evidently, Gamma-rays provide the potential for even better resolution than X-rays. Furthermore, gamma-ray sources providing intense streams of fluent emission are readily available, such as in the form of Cobalt-60. In the absence of the novel viable gamma-ray and X-ray semiconductor-processing techniques disclosed herein, various techniques for "stretching" the resolution of UV and visible light techniques have been contemplated. One such technique provides a method of forming short-channel polysilicon gates (0.6 .mu.m polysilicon feature size). (See, for example, U.S. Pat. No. 5,139,904, issued Aug. 18, 1992 to Auda et al.) This method employs a technique of laying down a layer of conventional photoresist over a polysilicon layer and patterning the photo-resist to "normal" dimensions (greater than the ultimately desired 0.6 .mu.m dimension). The photo-resist pattern is then uniformly eroded in all dimensions using an isotropic (non-directional) RIE (reactive ion etching) etch process. The size of features in the photo-resist pattern is carefully monitored during the etch process. When the pattern features are eroded to the desired size, the etch process is stopped. An anisotropic (highly directional) etch process is used to etch away portions of the underlying polysilicon outside of the "shadow" of the eroded photo-resist pattern (relative to a generally vertical etch direction). While this technique may be employed to produce small polysilicon structures, it has the same limitations as conventional photolithography with respect to line-to-line spacing. Because the photoresist is initially patterned to "conventional" dimensions, it is not possible with such "stretched" techniques to space pattern features substantially closer with sufficient resolution than is ordinarily possible with conventional photolithography. DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to provide improved techniques for fabricating semiconductor devices. It is another object of the present invention to provide improved techniques for forming ultra-fine features on a semiconductor device. It is another object of the present invention to provide techniques for forming features on a semiconductor device which are not limited by the resolving power of light. It is another object of the present invention to provide wafer processing techniques which yield improved critical dimensions (cd's) in semiconductor features. It is another object of the present invention to provide techniques capable of resolving smaller features (such as polysilicon or metal lines). It is another object of the present invention to provide near-field afocal techniques for processing semiconductor wafers. It is another object of the present invention to provide X-ray lithographic techniques. It is another object of the present invention to provide gamma ray lithographic techniques. It is another object of the present invention to provide means for "shuttering" gamma rays or X-rays. As used herein, the term"lithography" refers to any technique which is employed to define features on a semiconductor wafer, for example patterning photoresist overlying a layer that will subsequently be etched. Generally, all of the lithography techniques discussed hereinbelow employ some form of illumination (or radiating) source. According to the invention, lithography is performed on a semiconductor device using electromagnetic energy of shorter, or of substantially shorter wavelength, than visible or UV light. In one embodiment of the invention, X-rays are used as the illumination (radiation) source. According to an aspect of the invention, Beryllium is used as transparent image mask substrate for imaging X-rays onto a semiconductor wafer. Beryllium has excellent transparency to X-rays, and since it is a metal itself, carriers and opaque masking materials can be readily provided which have similar expansion coefficients, resulting in relatively low distortion of the mask. According to various aspects of the invention, Gold, Tungsten, Platinum, Barium, Lead, Iridium, or Rhodium are used as opaque mask materials to be deposited over a Beryllium substrate (image mask). All of these materials exhibit excellent opacity to X-rays. Further, these materials exhibit adequate adhesion to Beryllium (the image mask substrate) and adequate environmental robustness for utility as lithographic image masks. The resulting image mask (beryllium substrate with a pattern of opaque lines on a surface thereof) is suitably employed for "near field" lithography. By "near field" it is meant that the process is afocal, and by spacing the image mask close to the semiconductor wafer there is limited opportunity for the radiation passing through the image mask to spread. In another embodiment of the invention, Gamma-rays are used as the lithographic illumination source. According to an aspect of the invention, "base" organic resist materials applied to the semiconductor die (wafer) are doped either with organic or with inorganic materials (dopants) which exhibit high absorptivity to gamma-rays, to enhance the sensitivity of the resist material. Preferably, the dopant is inorganic. Examples of organic dopants include polystyrene, phenolformaldehyde, polyurethane, etc. Examples of inorganic dopants include bromine, chromium, tantalum, gold, platinum, palladium, lead, barium, boron, aluminum and magnesium. The dopants are highly reactive to incident gamma radiation, and produce secondary photon emissions of a different wavelength (longer) than that of the incident gamma rays. The organic resist base, which is not ordinarily reactive to gamma radiation, is however highly absorptive of these secondary emissions (from the dopants), which are actinic with respect to the organic resist base, thereby causing the resist base to become chemically converted. The high cross-section (absorptivity) of the organic resist base to the secondary emissions also limits the amount of "blooming" (spreading) inherent in the secondary emissions. According to another aspect of the invention, an organic resist material has an absorptive (to gamma radiation) film of material disposed on a surface thereof. The film atop the photoresist is organic or inorganic, preferably inorganic, and provides secondary emissions (photons) which convert the underlying photoresist. The film is termed a "secondary resist layer". Examples of organic resist materials suitable for the secondary resist layer include polystyrene, phenolformaldehyde, polyurethane, etc. Examples of inorganic secondary resist materials suitable for the secondary resist layer include bromine, chromium, tantalum, gold, platinum, palladium, lead, barium, boron, aluminum and magnesium. The secondary resist layer, when exposed to gamma radiation, produces secondary photon emissions of a different wavelength (longer) than that of the incident gamma rays. The underlying organic resist material is highly absorptive of these secondary emissions, which are actinic with respect to the organic resist, causing it to become chemically converted. The high cross-section (absorptivity) of the underlying organic resist to the secondary emissions, and its close juxtaposition to the overlying secondary resist film, limit the amount of "blooming" (spreading) that would otherwise be expected to be experienced. Other combinations of organic resist bases (or layers) either doped with high cross-section (to gamma radiation) dopants or underlying more absorptive (to gamma radiation) layers are disclosed and otherwise contemplated. Other aspects of the invention are directed to direct-write, afocal, lithography techniques and to means for directing, concentrating, collimating and shuttering beams of radiative energy. According to the invention, a broad incident beam of radiation can be concentrated and collimated, providing a very narrow, very intense beam of radiation (such as X-ray or gamma radiation) useful over a short range of distances as by means of a hollow, horn-shaped (e.g., conical) afocal concentrator (described extensively hereinafter). The afocal concentrator has a tapered section and a cylindrical section. The tapered section has a broad mouth at one end and a narrow opening at an opposite end. The cylindrical section has a diameter equal to that of the narrow opening, and is formed continuously therewith. A broad incident beam of radiation enters the mouth of-the tapered portion and is concentrated in the tapered portion and is collimated in the cylindrical portion to provide a collimated, intense output beam that can be directed onto a semiconductor wafer. In order to produce patterns on the wafer, either the collimator or the wafer is moved (in two axes). Preferably, the wafer would moved and the concentrator would be fixed in position. According to various aspects of the invention, the concentrator may have any of various tapered forms, including a linear, cone-shaped taper, an exponential taper, or some combination thereof. In any case, the inner surface of the afocal concentrator is highly reflective of the incident radiation. According to various other aspects of the invention, the afocal concentrator may be used to collimate (thereby intensify) any of various forms of radiation, including gamma radiation, X-ray radiation, UV light, and visible light. In the main hereinafter, the utility of the collimator for very short wavelength radiation that cannot be focused by conventional optics is discussed. According to other aspects of the invention, the reflective inner surface (bore) of the afocal concentrator is formed of aluminum, nickel, or chromium. The entire collimator can be formed of a single material, or its bore can be plated. According to the invention, a surface acoustic wave (SAW) device operating as a shallow angle scattering surface, can act as a shutter for X-ray or gamma-ray radiations. In the context of the present invention, such a shutter would controllably allow/prohibit the downstream (towards the wafer, or towards the concentrator) passage of radiation from a fluent, continuous source of radiation. A thin, reflective film of, for example, aluminum, nickel, or chromium, is disposed over the surface of a Surface Acoustic Wave (SAW) device. When the SAW device is not activated, the reflective surface is substantially planar, and reflects incident radiation at an angle equal and opposite to its angle of incidence. This beam, the position of which is highly predictable, can be used to pattern a layer (e.g., photoresist) on a semiconductor wafer. A tightly collimated beam approaching the surface of the SAW (such as from the aforementioned collimator) at a known shallow angle, will be reflected off of the reflective surface of the unactivated SAW device at a predictable angle. When the SAW device is activated, however, the surface of the SAW device becomes distorted and deflects or scatters the incident beam. By providing a beam stop or an aperture and positioning it such that radiation from the incident beam will pass the beam stop (or aperture) only when reflected at an angle corresponding to its reflection off of the planar surface of the unactivated SAW device, an effective shutter is formed. Hence, the planar and distorted surface of the SAW device, in combination with a knife-edge, opaque beam stop or aperture, effectively functions as a shutter, turning an incident beam ON and OFF, respectively, particularly for very short wavelength radiation (e.g., X-rays or Gamma rays). It is not necessary, according to the invention that the incident beam be "cleanly" reflected in any particular direction when the SAW device is activated (distorted surface). It is only necessary that the reflected beam be reflected from the SAW device anywhere other than past the beam stop or aperture when the SAW device is activated. In a similar manner, a magnetostrictive device may be employed instead of a SAW device, in combination with a beam stop or aperture, to form an effective shutter mechanism. Again, the surface of the magnetostrictive device can selectively be made planar, to reflect incident radiation past a beam stop or aperture, or it can be made non-planar, to divert incident radiation from passing the beam stop or aperture. As with the SAW device, the magnetostrictive device is coated with a material that is highly reflective vis-a-vis the incident radiation. In either case, namely employing a SAW device or a magnetostrictive device, the reflective element acts as a "surface distortion device" for the purposes of the present invention. Other devices whose surfaces may selectively be distorted may be employed, in combination with a beam stop or aperture, to achieve a similar shuttering function. According to various other aspects of the invention, the Surface Acoustic Wave or magnetostrictive shutter may be used to shutter radiation of a variety of wavelengths, including gamma-rays, X-rays, UV light, etc. In the main hereinafter, the utility of these surface distortion devices in conjunction with non-visible radiation is discussed. Further, according to the invention, direct-write gamma-ray lithographic apparatus is provided. An omni-directional radiation source provides a source of intense gamma-ray radiation. A suitable radiation source is a Cobalt-60 pellet which passively (without any external power) radiates intense, fluent (e.g., steady, not varying or intermittent) gamma-ray radiation. A reflector (similar to the reflector 114 discussed with respect to FIG. 1, above) may be employed behind the Cobalt-60 pellet to improve the directionality and intensity of the emissions from the pellet. Gamma-ray radiation from the gamma-ray radiation source enters (is incident to) a shutter device, such as the SAW or magnetostrictive-based shutter devices described above. The shutter device serves to selectively gate (block or pass) the incident beam, resulting in a controlled gamma-ray beam. The controlled gamma-ray beam enters the mouth of an afocal concentrator, such as that described above and in greater detail with respect to FIG. 4 et seq. The afocal concentrator narrows, intensifies and collimates the controlled beam to provide a collimated beam. A semiconductor wafer is positioned a distance from the output of the afocal concentrator such that the collimated beam impinges upon the surface thereof. The surface of the wafer is coated with a layer of gamma-sensitive resist, such as that described above. Preferably, the wafer is mounted to a movable carriage, by which means the wafer may be positioned such that the collimated beam may be caused to impinge on any point on the resist layer, to form a pattern in the resist layer for further processing (e.g., chemical etching). This is referred to as "direct write" lithography. The on/off state of the collimated beam may be effectively controlled by selectively activating and de-activating the shutter device. Preferably, the distance between the wafer and the output of the afocal concentrator is approximately 5 .mu.m. Even if the collimated beam of gamma radiation is not perfectly collimated, by positioning the wafer so close to the output of the collimator, there is not much opportunity for the collimated beam to spread out. In an alternate embodiment of the direct-write gamma-ray lithography apparatus described hereinabove, the positions of the shutter device and the afocal concentrator are reversed. In other words, the gamma radiation would be collimated, then shuttered, then caused to impinge on a semiconductor wafer. Other objects, features and advantages of the invention will become apparent in light of the following description thereof.
043953808	summary	The invention relates to the remote examination of pipes having communicating tubular extensions to determine whether or not such extensions are obstructed and relates particularly to the testing, at various times and from a remote position, of the flow through nozzles extending from headers in a cooling water spray system. In nuclear power plants, there is a containment building overlying the reactor. The building is circular and dome-like, and within the dome, there are a plurality of ring-shaped headers from which a plurality of nozzles extend. In the event of an accident, e.g. loss of reactor coolant circulation, a flow of water is automatically supplied through risers to the normally dry headers to spray from the nozzles to cool the interior of the building. Regulatory agencies usually require that the cooling spray headers and nozzles be tested every three years to demonstrate that they are not obstructed to an extent that the spray system is inadequate. The interior of the dome of the building may be as high as 140 feet above the floor of the building and the headers are near the dome. Although the building may also include a polar crane which is rotatable and which has a catwalk above the floor, the headers may be fifty feet or more above such catwalk. Therefore, the headers and nozzles are relatively inaccessible, and it is relatively time consuming and expensive to erect structures, such as scaffolding, to permit close examination of the nozzles. In addition, the headers and nozzles are usually made of stainless steel and great care must be taken to prevent exposing them to corrosive materials, such as small parts per million of halogens or compounds thereof, and therefore testing techniques as would involve such exposure must be avoided. Normally, the testing of the headers and nozzles is conducted while the reactor is shut down, and because the reactor shutdown time should be as short as possible, and because other tests may also be necessary during such shutdown time, it is necessary to conduct the header and nozzle testing within a short period of time. Usually, the spray system involves a large number, e.g. over 250, nozzles, and therefore, a system of testing is required which will permit the testing of each individual nozzle relatively rapidly. In those cases where the headers are only 15-30 feet from a platform or catwalk, it has been possible to supply air under pressure to the headers and check the air flow from each nozzle with a streamer on a long pole. However, even this technique can require three days of two shifts per day to complete the necessary testing. In other cases, where the headers are farther away from a platform or support, it had been proposed to test the outflow of air from the nozzles by means of a streamer supported by a tethered, helium-filled balloon, but this is time consuming and difficult to accomplish. Consideration has been given to supplying smoke or visible steam to the headers, and to then visually observe the issuance thereof from the nozzles. This is also impractical not only because the smoke or steam issuing from the nozzles obscures them making it difficult to ascertain that each nozzle is properly functioning, but also because such may include undesirable corrosive materials. I have discovered from tests that when heated air is forced through such headers and nozzles there is an unexpected effect, namely, a blocked nozzle does not reach a temperature as high as a nozzle through which the air flows freely. It is possible, therefore, to distinguish a blocked nozzle from an open nozzle on the basis of temperature. The explanation for this effect is not entirely clear because it would be expected that the temperature along the length of a nozzle would be substantially the same, and would be substantially the same as the temperature of the header to which it is attached due to the conductivity of the metal. However, it has been found that the temperature of an open nozzle, along its length, is many degrees higher than the temperature along the length of a blocked nozzle even though the temperature of both an open nozzle and a blocked nozzle a short distance from the header to which it is attached is less than the temperature of the header when heated air under pressure is supplied to the header. While there are various ways to measure remotely the temperatures of the nozzles, e.g. thermocouples, it is undesirable to make permanent installations requiring wires, etc., for remote observation, and it would be expensive and time-consuming to install such in already existing installations. I have further discovered that, considering both the distances involved and the nozzle temperature differences involved, infrared scanning techniques and apparatus, as developed today, are adequate to permit distinguishing between the temperature of a blocked nozzle and the temperature of an open nozzle with such apparatus located on a platform or catwalk normally located below the headers, at distances of up to 100 feet or more therefrom. Thus, by successively scanning the nozzles from a remote point while heated air is supplied to the headers under pressure, the location of any blocked nozzle or nozzles can be determined. One object of the invention is to provide a method of remote testing of the fluid flow through nozzles, which does not require any physical contact or interconnections with the nozzles. Another object of the invention is to provide a method of remote testing of the fluid flow through nozzles, which can be performed easily and in a relatively short time even though many nozzles are involved. In the preferred embodiment of the invention, clean air under pressure, e.g. at 100 lbs. p.s.i., and at a temperature substantially above ambient temperature, e.g. at a temperature of at least 100.degree. F., is supplied to a header having nozzles secured thereto, and the header and each nozzle is scanned with infrared scanning apparatus to provide thermograms thereof which are observed to determine whether or not the thermogram of each nozzle conforms to the thermogram of an open or a blocked nozzle. If desired a plurality of nozzles may be scanned simultaneously so that a plurality thereof appear in the same thermogram.
044997086	claims	1. In a method of using an electric discharge machine for forming a very narrow slot in a work piece with an electrode of thin cross section even narrower than the slot, comprising the steps of forming in the work piece typically by drilling two openings significantly large in diameter than the slot width at the opposite ends of where the slot will be, imposing a large potential between the electrode and the work piece, advancing the electrode toward the work piece to cause arcing under a bath of oil, whereby the slot is cut from the work piece and the slot as being cut is flushed by oil in the openings, and plugging the through openings with a durable solid material to leave only the slot. 2. A method of forming a very thin sample of reactive material, comprising the steps of melting the reactive material until it is in the liquid phase and then pouring the liquid reactive material into an extrusion cylinder and allowing it to cool to a solid, extruding a ribbon of the reactive material of thickness required of the sample, stamping out from the ribbon a disc of convenient shape and required size, sealing the disc in a protective package, and performing the previous steps in an inert atmosphere. 3. A method of forming a sample according to claim 2, wherein the protective package is an aluminum pouch formed by the steps of sandwiching the disc between two larger thin sheets of aluminum, and cold welding as a continuous annular seal the lapped edges of the aluminum sheets together in the area peripherally outside the disc. 4. A method of forming a sample according to claim 2, wherein the ribbon has a width in excess of 0.5 inch and a thickness of less than 0.01 inch. 5. A method of forming a sample according to claim 2 further providing the steps of forming a die to extrude the material through, wherein the work piece (die) first has larger openings formed therethrough spaced apart by the approximate width of the ribbon that will be extruded, and then using a very thin electrode in an electrical discharge machine to cut the slot between the openings in an oil bath whereby the bath oil moving within the openings provides flushing of the material away from the slot as the slot is being formed. 6. A method of forming a sample according to claim 5, wherein the steps of forming the die further include plugging the larger openings in the work piece with a durable material to leave only the slot in the die. 7. A method of forming a sample according to claim 6, wherein the ribbon has a width in excess of 0.5 inch and a thickness of less than 0.01 inch.
051788209	claims	1. A tool positioning assembly for use inside a steam generator having a manway opening in the wall of the steam generator, said tool positioning assembly comprising: a. a support base that is attachable to a steam generator at the manway opening, said support base comprising: b. a retractable foot assembly pivotally attached to said beam; c. a loading tool assembly removably attachable to said support base for inserting said support base into a steam generator; d. a four degree-of-freedom are removably received on said support base; e. a track assembly removably attachable to said support base and adapted to receive said arm for removably attaching said arm to said support base; f. a tool coupling mounted on said arm and adapted to receive remotely controlled tools. 2. The tool positioning assembly of claim 1, wherein said arm is provided with a driven cogwheel that engages said track assembly and said support base whereby said arm may be selectively driven and positioned along said track assembly and said support base.
	summary
	claims	1. A spent nuclear fuel storage facility comprising:an array of storage containers, each of the storage containers comprising:a body portion having a storage cavity and an open top end, the storage cavity configured to hold a canister containing spent nuclear fuel; anda lid detachably coupled to the body portion and enclosing the open top end, the lid comprising an inlet vent and an outlet vent each forming a passageway to ambient atmosphere; andwherein the lid of each of the storage containers comprises an upper flange portion extending over and sealably engaging the open top end of the body portion, and a lower cylindrical plug portion extending downwards from the flange portion, the plug portion insertably received through the open top end of the body portion into the storage cavity;the outlet vent extending through both the plug and flange portions placing the storage cavity in fluid communication with the ambient atmosphere through the lid;wherein each of the storage containers is configured to draw air through the inlet vent and into the storage cavity which is heated by the canister, and pass the heated air through the plug and flange portions of the lid via the outlet vent to the ambient atmosphere. 2. The spent nuclear fuel storage facility of claim 1 further comprising a canister containing spent nuclear fuel positioned within at least one of the storage containers, and wherein an entirety of the canister is positioned below grade. 3. The spent nuclear fuel storage facility of claim 1 further comprising a canister containing spent nuclear fuel positioned within each of the storage containers in the array, and wherein the canister within each of the storage containers is independently accessible and retrievable. 4. The spent nuclear fuel storage facility of claim 1 wherein the storage containers of the array are positioned in a spaced apart manner. 5. The spent nuclear fuel storage facility of claim 1 wherein each of the storage containers functions independently from each of the other storage containers and wherein air is drawn into and removed from the storage cavity of each of the storage containers via thermosiphon flow. 6. The spent nuclear fuel storage facility of claim 1 wherein the storage containers of the array are arranged in a plurality of aligned rows. 7. The spent nuclear fuel storage facility of claim 1 wherein an opening of the inlet vent is located at a periphery of the lid and wherein an opening of the outlet vent is located on a top surface of the lid. 8. The spent nuclear fuel storage facility of claim 1 wherein a majority of the body portion of the storage containers are located below grade, and wherein the inlet and outlet vents of the lid are located above grade. 9. The spent nuclear fuel storage facility of claim 8 wherein a portion of the body portion of the storage containers protrudes above grade, and further comprising a pad formed of a radiation shielding material positioned around the portion of the body portion of the storage containers, the inlet and outlet vents of the lid located above the pad. 10. The spent nuclear fuel storage facility of claim 9 wherein the pad is a continuous unitary structure that surrounds the portion of the body portion of each of the storage containers of the array. 11. The spent nuclear fuel storage facility of claim 1 wherein the inlet vent comprises a plurality of isolated openings formed into a sidewall of the lid and located circumferentially around the lid and wherein the outlet vent comprises a plurality of passageways extending from a plurality of isolated openings in a bottom surface of the lid to a common opening in a top surface of the lid located along a central axis of the lid, the plurality of passageways converging at the common opening. 12. The spent nuclear fuel storage facility of claim 11 wherein the top surface of the lid of each of the storage containers is curved and sloped downwardly away from the single opening. 13. The spent nuclear fuel storage facility of claim 1, wherein the outlet vent has an arcuately curved shape and fluidly communicates with the storage cavity via a plurality of bottom openings formed in a bottom of the plug portion of the lid. 14. The spent nuclear fuel storage facility of claim 13, wherein the bottom openings each have an arcuately curved shape. 15. The spent nuclear fuel storage facility of claim 1 wherein the outlet vent is formed by a curved steel plate embedded in concrete to increase a load bearing capacity of the lid. 16. The spent nuclear fuel storage facility of claim 1, further comprising an annular gasket seal on a bottom surface of the flange portion of the lid, the annular gasket seal sealably engaging the top end of the body portion of the storage container. 17. The spent nuclear fuel storage facility of claim 16, further comprising a container ring extending downward from the bottom surface and arranged to peripherally surround and engage an outside surface of the body portion of the storage container when the lid is positioned atop the body portion. 18. A spent nuclear fuel storage facility comprising:an array of storage containers, each of the storage containers comprising:a body portion having a storage cavity and an open top end, the storage cavity configured to hold a canister containing spent nuclear fuel; anda concrete-filled lid detachably coupled to the body portion and enclosing the open top end;the lid of each of the storage containers comprising an upper flange portion extending over and sealably engaging the open top end of the body portion, and a lower cylindrical plug portion extending downwards from the flange portion, the plug portion insertably received through the open top end of the body portion into the storage cavity;a plurality of outlet vents disposed in the plug portion of the lid, each outlet vent forming a passageway from an opening in a bottom surface of the plug portion to a central opening in a top surface of the lid;a plurality of inlet vents circumferentially located around the flange portion of the lid, each inlet forming a passageway from an opening in a side wall of the flange portion to an opening in a bottom surface of the flange portion;wherein each of the storage containers is configured to draw air through the inlet vents and into the storage cavity which is heated by the canister, and pass the heated air through the plug and flange portions of the lid via the outlet vents to ambient atmosphere. 19. The spent nuclear fuel storage facility of claim 18, wherein the outlet vents each have an arcuately curved shape formed by a curved steel plate embedded in the concrete in the lid to increase a load bearing capacity of the lid.
050248065	abstract	A debris filter bottom nozzle of a nuclear fuel assembly is spaced below the lowermost grid, supports the guide thimbles, and is adapted to allow flow of liquid coolant into the fuel assembly. The debris filter bottom nozzle includes an enclosure defining a coolant flow chamber therethrough, and an upper transverse nozzle structure composed of a consolidated array of elongated cylindrical sections disposed across the chamber of the enclosure in side-by-side relation to one another, extending axially in the direction of coolant flow through the chamber, rigidly connected together and to the enclosure, and having tubular cross-sectional configurations defining passages for the coolant flow through the chamber.
	summary
044141769	description	DETAILED DESCRIPTION OF THE INVENTION The invention relates to a metallic member exposed to plasma in a plasma device and subject to a loss of metal from its surface by erosion and more specifically by sputtering. In the invention a metallic member such as a first wall or limiter is constructed of a substrate composed of a major amount of a first metal and a thin surface layer of a second metal. The term substrate is here construed as applying to any bulk material in which a surface has a composition or structure different from that of the bulk. In this metallic combination, less metal escapes from the surface than would occur when the second metal is in bulk form. In addition, the metal escaping from the surface has a higher secondary ion/neutral ratio and therefore a greater portion of the second metal leaving the surface is returned. In another aspect of the invention, the substrate is composed of a major amount of a first metal and minor amount of a second metal so that the substrate provides a self-sustaining source of the second metal to the surface. Preferably the first metal is more electromegative than the second metal and the second metal is selected from the group consisting of alkali and alkaline earth metals, preferably those with low atomic number. Further, the metals are selected so that the binding energy between like atoms of the first metal is greater than the binding energy between atoms of the first and second metals which in turn is greater than the binding energy for like atoms of the second metal. The substrate provides a self-sustaining source of the second metal by at least two processes. In the first, the metals are selected to satisfy the equation EQU H.sub.1,2 =.OMEGA.+1/2(H.sub.1,1 +H.sub.2,2) where .OMEGA..ltoreq.0, and H represents an enthalpy of sublimation for the alloy and the pure first and second metals. Under these conditions and when the substrate or structural member is heated to an elevated temperature or subjected to another energy source, the first or surface layer becomes enriched with the second metal to form a monolayer composed primarily of the second metal. Another mechanism which also causes segregation results from radiation damage. In a second process when the substrate or structural member has a concentration of metals forming an intermetallic compound, the surface is subjected to an initial treatment of radiation including bombardment with particles. Since the second metal forms secondary ions in greater amounts than the first metal, the removal of the surface atoms results in a selective return of the second metal to form a monolayer of the second metal. Further, as the binding energy of like atoms of the second metal is below that for different atoms of the two metals, returning atoms of the second metal will move to vacant sites above atoms of the first metal and therefore aid in maintaining the monolayer of the second metal. The invention provides several advantages. It provides a metallic member and particularly a first wall or limiter with a substrate constructed with a reasonable degree of structural strength and ease of fabrication, together with a surface having a reduced loss of metal by erosion or sputtering, and a higher secondary ion/neutral ratio. In addition, by providing a self-sustaining source of second metal for the surface of the first wall or limiter, the invention provides a surface with improved performance characteristics. The invention is particularly useful in a plasma device in which a plasma is generated and heated to an elevated temperature. A number of plasma devices have been constructed to provide a means for conducting experiments in the field of thermonuclear reactions. FIG. 1 represents a sectional view of a plasma device 10 with a plasma 16 magnetically confined within a chamber 18. Additional parts of the plasma device as shown include the magnetic coil 20, a shield 22, a plenum chamber 24, and rf duct 26. In the plasma device 10, hot plasma 16 at temperatures of about 1.times.10.sup.8o K is magnetically confined within the first wall 12 whose purpose is to limit the number of particles escaping from the plasma. The limiter 14 reinforces this purpose and is at a negative sheath potential of about 20-500 eV. The surface 28 of the first wall 12 and surfaces 30 of the limiter 14 are both subject to erosion by loss of metal due to vaporization of the metal at the elevated temperature of 300.degree.-3500.degree. C. and also by sputtering. Sputtering may occur when particles from the plasma strike the metallic surfaces 28 and 30. If the sputtered particles are secondary ions, they are returned to the emitting surface by the toroidal field regardless of charge sign. If the secondary ions are emitted from the limiter, or the wall in a limiter-less device, the sheath potential provides an additional means of returning the positive ions which comprise the vast majority of the secondary ions. If the sputtered particles are neutral and depending on their kinetic energies, they will penetrate sufficiently far into the plasma for charge exchange collisions to occur. At that point, they will become ionized but the ions will then be subject to plasma transport processes and some of the particles will therefore tend to continue into the plasma causing a reduction in the plasma energy available for the desired thermonuclear reactions. In the inventive metallic member represented by the first wall 12 and limiter 14, each pair of different atoms of the first and second metals have a binding energy above the value for like atoms of the second metal and therefore are at a reduced vapor pressure from their pressure in bulk form. This results in a reduced loss from the surface of the wall or limiter. Preferably the surface layer is a monolayer composed of atoms of the second metal with ionic bonds to atoms of the first metal as generally illustrated in FIG. 2. The presence of the monolayer also serves to shield the substrate from sputtering, especially under the conditions of low energy-light ion sputtering encountered in plasma devices. Therefore, the erosion of the substrate metal which produces predominantly neutral atoms which have a relatively high likelihood of entering the plasma is reduced. In addition, returning atoms of the second metal will have a greater affinity towards atoms of the first metal due to the higher binding energies and will move to vacancies in the monolayer where atoms of the first metal are exposed thereby maintaining the integrity of the monolayer. As illustrated in FIG. 2, a particle 40 from the plasma 16 strikes the surface 41 of the wall 12 or limiter 14 and causes an atom 42 of the second metal to leave the surface 41. That atom may move in two paths 44 and 46 depending on whether or not the atom is attracted to the surface 41 by the sheath potential or magnetic field. In some instances, the atom 42 will initially move to a position over a like atom 48 before it moves along path 50 to a vacant site 52. Substrate 54 is illustrated as containing only molybdenum although as disclosed below, minor amounts of the second metal may be present to provide a self-regenerating and self-sustaining surface of the second metal. The surface metal or second metal is an alkali or alkaline earth metal including Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba with those with a lower atomic number having an advantage since their effect on reduction in energy of the plasma is less than those metals with greater atomic number. However, a heavier metal such as cesium has advantages since it may provide a higher ion fraction than lithium. The metal comprising the major portion of the substrate is more electronegative than the surface metal, has preferably a high melting point relative to the second metal, a high solubility for the second metal, a high surface binding energy, and a high heat of sublimation. Suitably, a first metal includes Al, Si, Cu, Au, B, Mg, Pb, Bi, C, Ag and Ca, and may form either an alloy or intermetallic compound with the second metal. In the case of the compound, it should be noted that the melting point of the compound may be higher than that of either element, and that it is the compound's melting point that, in fact, determines the suitability for use in a plasma device. The first metal will be more electronegative than the alkali or alkaline earth second metal. The substrate may include combinations of the first metal such as stainless steel formulations, particularly when the self-sustaining feature is not utilized. When the substrate is intended to provide a source of the second metal, and the substrate is in the form of an alloy, the second metal may be present in quantities as low as a few ppm, with preferred upper limit of about 20 at.%. For the process involving selective erosion of an intemetallic compound (e.g., Li.sub.2 Si or BaAl.sub.4) the second metal should constitute from about 15 at.% to about 70 at.% and preferably about 50 at.%. When the substrate is compound of a mixture of metals forming an alloy, the metals are selected to satisfy the equation EQU H.sub.1,2 =.OMEGA.+1/2(H.sub.1,1 +H.sub.2,2). The above equation is further described by Williams and Nason in the reference Surface Science, 45, (1974) 377. Briefly, the equation relates the enthalpy (H.sub.1,2) of the sublimation for the alloy and first and second metals in terms of the solution parameter ".OMEGA." which equals zero for an ideal solution. When .OMEGA..ltoreq.0, the second metal in the alloy becomes segregated to form essentially a monolayer on the surface. In this process continuing as the surface is eroded, the surface is maintained with added amounts of the second metal. As further illustrated in FIG. 4 which represents a graph characterizing the effect of the selection of metals satisfying the above equation; when .OMEGA. is negative, the concentration of the minor constituent is highest at the first layer and decreases to a very low value in the second layer after which it returns to the bulk value. The final difference in concentration between the first and second layers results in a more stable condition than would be associated with random distribution of the second metal in the substrate. As also illustrated in FIG. 4, when .OMEGA. is positive, the extreme difference in concentration of the second metal between the first and second layers does not occur. When .OMEGA. is negative, the effect illustrated in FIG. 4 is achieved by providing a mixture of metals as described above and applying energy to the substrate sufficient to cause the atoms of the second metal to migrate and form a surface layer composed predominantly of the second metal with a second layer having a greatly decreased concentration of the second metal. Preferably, the energy is applied by heating the substrate to an elevated temperature at least about 300.degree. C. and preferably about 300.degree.-600.degree. C. As the surface layer loses atoms of the second metal and with the substrate at an elevated temperature, atoms of the second metal are transferred to the surface by segregation to maintain the concentration difference between the first and second layers. Another process by which atoms of the second metal are transferred or migrate in the substrate is associated with a radiation-induced segregation. In this process, voids or other sites are created in the substrate by radiation damage and atoms of the second metal move with these sites to the surface to provide atoms of the second metal on the surface. As illustrated in the pictorial representation of a substrate in FIG. 5 containing an alloy 60 forming segregated layers, the surface 62 of first layer 64 is a monolayer of the second metal 66 such as potassium with the next below layer 68 comprising the first metal 70 such as aluminum with a small amount of the second metal 66. Additional layers 72 and 74 are composed of the first metal with the second metal being present in approximately the bulk concentration. In some instances, the combination of the first and second metals will result in an intermetallic compound where the atoms of the second metal are relatively fixed in the structure. Illustrations of these compounds are BaAl.sub.4, Li.sub.2 Si, Li.sub.5 B.sub.4 Li.sub.3 Bi, and Li.sub.4 Ca. Under these combinations, the substrate will provide the desired surface layer by selective removal of atoms of the first metal from the surface. Since atoms of the first metal will escape from the surface as neutrals, the second metal will increase in concentration at the surface due to the return of atoms of the second metal as secondary ions to the surface. The selective removal of the first metal from the surface is carried out by subjecting the substrate to an initial bombardment stage. After the formation of the surface layer of the second metal, some amounts of the second metal will be lost during operation of the plasma device. Returning atoms of the second metal under the effects of the electrical and/or magnetic fields will reform the surface over atoms of the first metal. In addition, exposed atoms of the first metal will be removed by bombardment so that the surface layer will continue to be characterized by a predominance of the second metal. For purposes of illustration, the surface of the intermetallic compound at the initial stage may be represented as follows: ##STR1## where "A" and "B" represent atoms of the second and first metals. As "B" is selectively removed, a layer of "A" remains to form a monolayer. EXAMPLES I-II Two tests were conducted on the sputtering behavior of a layer of potassium on molybdenum. The equipment included a bakeable, ion pumped stainless steel UHV sample chamber in which is installed commercial Auger electron (AES) and x-ray photoemission (XPS) spectrometers, a differentially pumped 5 KeV ion gun, and a laboratory-constructed secondary ion mass and energy analyzer. The ion gun has been modified so that an internal pressure readout signal can be provided to the servo-controlled gas inlet valve to obtain pressure stabilization. Electron and ion beam currents were measured by a Faraday cup which can be moved into the sample position. The ion gun was capable of producing a beam spot 200 .mu.m in diameter and the beam was rastered over an area larger than the sample to avoid effects arising from beam nonuniformity. Ion beam current densities ranged from about 0.7 to 10 .mu. A/cm.sup.2. A potassium layer was produced from a source constructed of a porous tungsten plug impregnated with a potassium alumino-silicate analogous to a commerical molecular sieve. When heated, the source emitted potassium ions. The source was placed approximately 10 cm from the sample to reduce surface heating, and a molybdenum heat shield and collimator with a 6 cm diameter aperture was placed approximately equidistant between the source and sample. A bias of about 45 volts was applied to the source during deposition to supply an extraction potential. The spectrometers, ion gun and potassium source were positioned so that it was possible to deposit, sputter and operate all of the analyzers without changing the sample position. Potassium deposition on the molybdenum substrate was monitored either by AES or XPS. Because of the power radiated by the potassium source, the sample temperature increased to about 90.degree.-100.degree. C. during deposition. At this temperature, bulk potassium is above its melting point and has a vapor pressure of about 10.sup.-4 Torr. The time for the deposition of potassium was about two hours and the potassium signal was normalized to the Mo line intensity for each scan to correct for fluctuations in the output of the x-ray tube. After about two hours, the potassium source and sample bias were turned off and a 1 KeV He.sup.+ beam was turned on. The potassium signal fell at a constant rate for several hours, followed by an abrupt change to a new, slower rate indicating that less potassium was escaping from the surface. The data in FIG. 3 obtained without sample bias are indicated by the symbol "0". The test was then repeated under the same conditions except that a bias of about -21 volts was applied to the sample. An identical or near identical initial sputtering rate and the same abrupt change were noted; however, the erosion rate following the abrupt change was lower than in the previous test. For this test, the data are indicated by the symbol ".DELTA.". The results of the tests are shown in FIG. 3. As indicated, the initial sputtering resulted in the removal of potassium as neutral atoms until a monolayer was formed (as calibrated by AES). After the monolayer was formed, potassium ions on the surface escaped as secondary ions in the absence of an applied potential. In the second test, when the negative potential of about 21 eV was applied to the sample, the rate became further reduced due to the return of secondary ions to the surface. In addition to the rates shown in FIG. 3, the sputtering cross section in FIG. 3 was measured. The initial sputtering cross section was about 6.6.times.10.sup.-18 cm.sup.2, with values for the lower line representing the test without bias being about 3.6.times.10.sup.-18 cm.sup.2 and for the lower line representing the test with bias being about 1.9.times.10.sup.-18 cm.sup.2.
053612795	abstract	A hydraulically based control rod drive system that is contained within the pressure vessel is disclosed for positioning the control rods relative to fuel rods positioned in a nuclear core of a boiling water reactor. Hydraulic jacks mounted on an open grid located entirely within the pressure vessel at a position above the nuclear core are used to position the control rods. Suitable jack and grid structures, as well as a hydraulic control arrangements are described.
	description	The present invention relates to methods for providing a dry environment for underwater repair of reactor bottom heads in a restrictive access environment. There is an emerging need for effecting weld repairs at the bottom head of boiling water reactors. For example stub tubes, incore housing penetrations, pressure lines penetrations and cladding surface repair along the bottom head of the nuclear reactor vessel often require weld repairs. Generally, such weld head repairs have been effected subsequent to draining the nuclear reactor vessel in order to provide a dry environment for welding. Accordingly, there is a need for a method of effecting weld repairs and inspections at the bottom head of nuclear reactor vessels in a totally dry environment and without draining the reactor vessel. In a preferred embodiment of the present invention there is provided, in a nuclear reactor vessel having a core plate and a generally hemispherically shaped bottom head with a plurality of penetrations enabling control rod drives to pass through the penetrations to support control rods, a method of repairing or mitigating crack formation at the bottom head of the vessel comprising the steps of: passing segments of a first caisson through holes in the core plate to a location about a tube secured to the bottom head and surrounding a penetration; assembling the segments about the tube; sealing the segments to one another and to the bottom head; passing a second caisson through a core plate hole and into engagement with the first caisson; removing water from the first and second caissons to provide a water-free environment for welding; and lowering a welding head through the second caisson and into the first caisson to apply a weld about the tube or along the bottom head. In another preferred embodiment of the present invention, there is provided in a nuclear reactor vessel having a core plate and a generally hemispherically shaped bottom head, a method of repairing or mitigating crack formation at the bottom head of the vessel comprising the steps of: passing segments of a first caisson through holes in a core plate to a location adjacent the bottom head; assembling the segments to form an enclosure; sealing the segments to one another and to the bottom head; passing a second caisson through a core plate hole and sealing a lower end thereof to the first caisson; removing water from the first and second caissons to provide a water-free environment for welding; and lowering a welding head through the second caisson and into the first caisson to apply a weld. Referring now to FIG. 1 there is illustrated a nuclear reactor vessel generally designated 10 and including a plurality of fuel assemblies 12 carried on a core plate 14, a top guide 16, a steam separator assembly 18, steam dryer assembly 20 and a top head 22. The core plate has a plurality of openings 15. Below the core plate 14, there is provided a generally hemispherically shaped bottom head 24 through which various penetrations are made including stub tubes 26 and control rod housings 34 through which control rod drives 28 are received as well as other incore housings. It will be appreciated that the bottom head contains the water within the vessel 10. Also illustrated is the core shroud 30 which surrounds the core and provides a barrier to separate the upper flow through the core from the downward flow between the annular core shroud 30 and the outer wall of the vessel. It will also be appreciated that each of the fuel assemblies that makes up the core rests on an orificed mounted on top of the control rod guide tubes. The top guide 16 engages the top of each fuel assembly and provides lateral support for the fuel assemblies. Referring to FIGS. 2-4, there are illustrated control rod drive housings 34 and stub tubes 26 secured to the hemispherical bottom head 24, the steel cladding 37 of which lies along the inside surface thereof. As noted previously, weld repairs are often times necessary adjacent to the bottom head 24, e.g., about the stub tubes 26 and for cladding surface repair on the bottom head. Previously, the reactor vessel was drained of the water to effect the repairs. However, it is more economical if the vessel does not require draining to perform these repairs and instead the repairs can be effected underwater. This necessitates a dry environment. In accordance with a preferred aspect of the present invention, a dry welding environment is provided by deploying a caisson. However, providing a caisson to effect a dry environment for welding presents certain difficulties. For example, locating the caisson on the hemispherical and uneven cladding surface along the bottom head is difficult because the diametrical size of the core plate holes through which all equipment must pass to obtain access to the interior of the bottom head imposes a size limitation. Secondly, it is difficult to seal the caisson against the very uneven surface of the bottom head due to the presence of the cladding on the hemispherical surface. It is even more difficult to seal the caisson on the steep incline of the bottom head adjacent the outer periphery of the head. Generally, the diameter of the core plate holes are smaller than the space needed to pass a caisson through a hole. The holes are also too small for a welding apparatus to maneuver in the work area, i.e., to be passed through the core plate hole to a location adjacent the interior surface of the bottom head. The present invention addresses those two problems by providing a segmented lower caisson 48 in which segments are receivable through the core plate holes for assembly adjacent the interior surface of the bottom head. Each segment for each lower caisson may be unique dependent upon its location along the interior surface of the bottom head. Because of the hemispherical shape of the bottom head at each location in which weld repairs are to be effected, it will be appreciated that the lower edges of each segmented caisson are beveled or tapered to form an edge complementary to the shape of the bottom head at that location. For example, as illustrated in FIGS. 2 and 5, a lower caisson segment 50 includes a wall, preferably in the shape of a quadrant of a cylinder, having a lower edge generally complementary to the shape of the interior surface of the bottom head 24 to which the lower edge of the segment will be sealed to form, in conjunction with other caisson segments a dry caisson environment. The upper edge of the caisson segment 50 has a flat inwardly directed flange 52 which, when all of the caisson segments are sealed and secured about for example a stub tube 26, will form a horizontal support surface for receiving the lower edge of an upper cylindrical caisson. In FIG. 2, one segment is illustrated; in FIG. 3 two segments are illustrated and in FIG. 4 four segments forming a complete annulus about the stub tube 6 are illustrated. It will also be appreciated that the final assembled annulus, as described below, has a diameter larger than the diameter of the core plate openings 15 and hence cannot be passed through those core plate openings 15 in its assembled condition. To form the lower caisson about the stub tube or to secure a lower caisson to the bottom head to effect weld repairs and without first draining water from the reactor vessel, segment holddowns 53 are first installed. Referring to FIG. 2, each segment holddown 53 includes a ring 54 sized to engage about an adjacent control rod drive housing 34 and a separate holddown lug 56. The ring 54 and lug 56 are sized to pass through the core plate holes 15. With the ring properly positioned about a control rod drive housing 34 using suitable conventional tools, the separate lug 56 can be bolted to one side of the ring 54 adjacent to the stub tube 36 to which repairs will be effected. The lug 56 includes a flange 58 which, when assembled to the ring 54, may overlie and hold down the caisson segment 50. With four segment holddowns 53 in place on housings 34 surrounding the stub tube 26 in need of repair, the four segments 50 are arranged in sequence, i.e., inserted through the core plate openings 15 and located below the flanges 58. Alternatively, each holddown 53 is installed followed by installation of a segment 50, which is located below the flange 58 of the installed holddown 53. Thus, the flanges 58 on the lugs 56 hold the segments between the flanges and the interior surface of the bottom head 24. As illustrated in FIG. 4, the four segments of the lower caisson thus form an annulus about the stub tube 26 and their lower edges are held against the interior surface of the bottom head 24. A water curable polymer is pressure injected into all of the joints between the segments 50 of the lower caisson and also between the lower edges of the caisson segments and the interior surface 37 of the bottom head 24. Because the water curable polymer is able to flow, it fills all the cavities that are potential leak paths. Moreover, the segmented lower caisson is provided at a height and width that allows room for a welding tool or torch to maneuver between the stub tube and the segmented caisson, but which is sufficiently short to minimize assembly efforts. Also, the final assembled lower caisson provides a horizontal flanged flat surface 52 that enables an upper second and taller dry caisson 60 to mate with it. The second caisson has a diameter smaller than the diameter of the core plate holes 15 enabling the second caisson to be lowered through the core plate holes such that its lower annular edge seats on the horizontal annular flange 52 of the lower caisson. A seal 62 is provided between the upper and lower caissons, e.g., an o-ring seal may be provided on the lower end of the upper caisson to seal against the flange. The upper caisson 60 may be provided in discrete lengths with seals, e.g., o-ring seals, between each length such that the upper end of the upper caisson 60 extends into the volume of the upper head 22. With the lower caisson 48 sealed to the bottom head 24 and the upper caisson 60 sealed to the lower caisson 48, the water within the caissons can be pumped such that the caissons 48, 60 are evacuated. Once evacuated, the welding equipment may be disposed through the upper caisson 60 into the lower caisson 48 and a welding head 64 (see FIG. 6) is located to effect the repair along the stub tube 26 or the cladding 37 of the interior surface of the bottom head 24 in a dry environment. Tig welding processes may be utilized. Once the repair or repairs have been effected, the welding equipment can be withdrawn, the caissons removed and the holddowns removed as well. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
	abstract	There are provided a generator internal pipe section that extends in the horizontal direction inside a steam generator; and a communication pipe section that is connected to the generator internal pipe section and is provided with a communication path, wherein one end of the communication path is connected to the pipe path at an upper end of a cross-section perpendicular to the flow direction of the cooling water in the pipe path and the other end of the communication path is positioned at the downside in the vertical direction in relation to one end of the communication path, and wherein one end side and the other end side of the communication path are connected at a position existing at the upside in the vertical direction in relation to one end.
	claims	1. A method for delivery of a tool into a nuclear reactor jet pump submerged in a reactor pool, the method comprising:generating a plurality of command signals at a remotely located tool delivery device control module;positioning a tool delivery device having a submarine assembly adjacent an inlet of the jet pump within the reactor pool using at least one propulsion drive operably connected to the submarine assembly and responsive to at least one of the remotely generated command signals, the submarine assembly being interoperably coupled to a guide assembly via a linear coupling;maintaining a tool position controller of the submarine assembly in a substantially stable and constant location within the reactor pool adjacent the inlet of the jet pump utilizing a ballasted floatation assembly configured to provide stability to the submarine assembly;positioning a guide latch of the guide assembly in contact with the inlet of the jet pump, in response to at least one of the remotely generated command signals, utilizing the linear coupling to move the guide assembly relative to the substantially stable submarine assembly;coupling the guide latch to the inlet of the jet pump, in response to at least one of the remotely generated command signals; andinserting a tool from the tool delivery device through the guide assembly, the inlet, and into the jet pump using the tool position controller of the submarine assembly. 2. The method of claim 1, wherein generating the plurality of command signals comprises:generating the command signals at the remotely located tool delivery device control module; andtransmitting the command signals to the tool delivery device via at least one communications link. 3. The method of claim 1, further comprising generating a video signal indicative of a position of the tool delivery device within the pool from a camera mounted on the tool delivery device and transmitting the video signal to a display device associated with the control module. 4. The method of claim 1, further comprising generating a position signal indicative of the position of the tool delivery device within the pool from a position sensor mounted on the tool delivery device and transmitting the position signal to a position monitor associated with the control module. 5. The method of claim 1, further comprising transmitting a position signal from a position sensor mounted on the tool delivery device to the control module, the position signal indicative of the position of the tool delivery device within the pool, generating a plurality of movement control commands as a function of the received position signal, and transmitting the movement control commands to the tool delivery device. 6. The method of claim 1, further comprising tracking the position of the inserted tool via position signals transmitted from a position sensor mounted on the tool to the control module. 7. The method of claim 1 wherein the tool is an inspection probe, and inserting the tool from the tool delivery device through the inlet and into the jet pump comprises activating and deactivating the inspection probe within the jet pump to inspect an internal surface of the jet pump. 8. The method of claim 1, further comprising controlling a position of the inserted tool within the jet pump using the tool position controller. 9. The method of claim 1, further comprising withdrawing the tool from the jet pump using the tool position controller. 10. The method of claim 1, further comprising decoupling the tool delivery device guide latch from the jet pump inlet, via at least one of the remotely generated command signals. 11. The method of claim 1, further comprising placing the tool delivery device into the reactor pool containing a plurality of jet pumps. 12. The method of claim 1 wherein the tool delivery device includes a plurality of propulsion drives for moving the tool delivery device in three dimensions within the pool. 13. The method of claim 1 wherein the tool delivery device includes a guide for inserting one or more tools through the inlet and into the jet pump, and wherein positioning the tool delivery device adjacent an inlet of the jet pump comprises compressively engaging a portion of the guide to an edge of the inlet to at least partially stabilize a position of the tool delivery device relative to the inlet and the jet pump. 14. The method of claim 1 wherein inserting a tool from the tool delivery device through the inlet comprises:delivering the tool through the inlet and into a cylindrically or conically shaped portion of the jet pump by controlling a support cable connected between the tool delivery device and the tool; andproviding an umbilical line connected between the tool and the tool position controller for controlling an operation of the tool. 15. The method of claim 13, further including generating a video signal indicative of the position and operation of the guide about the inlet from a camera mounted on the tool delivery device and transmitting the video signal to a display device associated with the control module.
	abstract	A method of data preparation in lithography processes is described. The method includes providing an integrated circuit (IC) layout design in a graphic database system (GDS) grid, converting the IC layout design GDS grid to a first exposure grid, applying a non-directional dither technique to the first exposure, coincident with applying dithering to the first expose grid, applying a grid shift to the first exposure grid to generate a grid-shifted exposure grid and applying a dither to the grid-shifted exposure grid, and adding the first exposure grid (after receiving dithering) to the grid-shifted exposure grid (after receiving dithering) to generate a second exposure grid.
	claims	1. A reactor containment vessel comprising:a primary reactor containment vessel containing a reactor pressure vessel and having a certain pressure resistance higher than atmospheric pressure and a certain leak-tightness;a secondary reactor containment vessel installed outside of the primary reactor containment vessel and having a pressure resistance and a leak-tightness equivalent to the pressure resistance and the leak-tightness of the primary reactor containment vessel;an air bag installed in a folded state in the secondary reactor containment vessel, and upon an occurrence of an accident in the primary reactor containment vessel, the air bag is configured toreceive high-pressure gas released from the primary reactor containment vessel, andexpand from the folded state to an expanded state while confining the gas therein; anda gas phase vent pipe connecting the primary reactor containment vessel and the air bag,wherein a pressure in the air bag is equalized with a pressure in the secondary containment vessel at a time when expansion of the air bag is finished, thereby passively preventing leakage of the high-pressure gas from the primary containment vessel and the air bag. 2. The reactor containment vessel according to claim 1, whereinan isolation-communication switching unit is attached to the gas phase vent pipe. 3. The reactor containment vessel according to claim 1, whereinthe primary reactor containment vessel includes a dry well containing the reactor pressure vessel and a wet well containing a suppression pool at its lower part and a gas phase at its upper part,the secondary reactor containment vessel is disposed above the primary reactor containment vessel, andthe gas phase vent pipe connects the air bag and a gas phase of the wet well. 4. The reactor containment vessel according to claim 3, whereinthe secondary reactor containment vessel includes an operation floor and is separated from the primary reactor containment vessel by a primary reactor containment vessel upper lid. 5. The reactor containment vessel according to claim 3, whereina pool storing cooling water is installed inside the secondary reactor containment vessel, and a water surface of the cooling water in the pool is exposed to an atmosphere in the secondary reactor containment vessel,a strainer is installed inside the pool, and a drain pipe is guided to inside of the dry well by the strainer,a leading end of the drain pipe is opened in a lower dry well disposed below a vessel support for supporting the reactor pressure vessel in the dry well through a check valve, a U-shape seal, and an injection valve, and,when the air bag is expanded to cause pressure in the secondary reactor containment vessel to rise, the atmosphere in the secondary reactor containment vessel pressurizes the water surface of the cooling water in the pool to allow the cooling water to be guided to the lower dry well. 6. The reactor containment vessel according to claim 5, whereina core catcher is installed on a floor of the lower dry well, and,when the air bag is expanded to cause the pressure in the secondary reactor containment vessel to rise, the atmosphere in the secondary reactor containment vessel pressurizes the water surface of the cooling water in the pool to allow the cooling water to be guided to the lower dry well so as to flood core debris dropped in the core catcher for cooling. 7. A nuclear power plant comprising:a reactor pressure vessel incorporating core fuel;a primary reactor containment vessel containing a reactor pressure vessel and having a certain pressure resistance higher than atmospheric pressure and a certain leak-tightness;a secondary reactor containment vessel installed outside of the primary reactor containment vessel and having a pressure resistance and a leak- tightness equivalent to the pressure resistance and the leak-tightness of the primary reactor containment vessel;an air bag installed in a folded state in the secondary reactor containment vessel, and upon an occurrence of an accident in the primary reactor containment vessel, the air bag is configured toreceive high-pressure gas released from the primary reactor containment vessel, andexpand from the folded state to an expanded state while confining the gas therein; anda gas phase vent pipe connecting the primary reactor containment vessel and the air bag;wherein a pressure in the air bag is equalized with a pressure in the secondary containment vessel at a time when expansion of the air bag is finished, thereby passively preventing leakage of the high-pressure gas from the primary containment vessel and the air bag. 8. The reactor containment vessel according to claim 1, wherein the air bag is comprised of a plastic material. 9. The nuclear power plant according to claim 7, wherein the air bag is comprised of a plastic material.
	claims	1. A method of operating a pressurized water reactor having a containment structure containing an integral reactor comprising at least one steam generator mounted together with a reactor core in a pool of reactor coolant in a reactor pressure vessel and with the at least one steam generator having a secondary loop extending outside of the containment structure, the method comprising: in response to a loss coolant accident resulting in a mass flow of reactor coolant out of the reactor pressure vessel into the containment structure, circulating cooling fluid through the secondary circuit of the at least one steam generator to withdraw heat from the reactor pressure vessel and thereby condense steam within the reactor pressure vessel; and extracting the heat from the cooling water outside of the containment structure at a rate which, within no more than about 3 hours, condenses sufficient steam in the reactor pressure vessel to lower pressure in the reactor pressure vessel to a pressure at or below pressure in the containment structure resulting from the loss of coolant accident and thereby stopping or reversing the mass flow of reactor coolant from the reactor pressure vessel whereby the reactor core remains covered without the addition of water from other sources to the reactor pressure vessel. 2. The method of claim 1 comprising the further steps of: claim 1 including at least one suppression tank containing water in the containment structure; introducing steam in the containment structure resulting from the loss of coolant accident into the water in the at least one suppression tank to condense the steam; and selectively transferring water from the at least one suppression tank to the reactor pressure vessel to keep the reactor core covered with water. 3. The method of claim 2 including mounting the at least one suppression tank above the reactor core and transferring the water to the reactor pressure vessel by gravity. claim 2 4. The method of claim 3 further comprising: claim 3 disposing a lower portion of the reactor pressure vessel containing the reactor core in a flood-up cavity in the containment structure; using gas in the at least one suppression tank above the water, which gas is compressed by the addition of a gas/steam mixture from the pressurized containment structure to passively transfer at least some water in the at least one suppression tank to the flood-up cavity. 5. The method of claim 4 wherein the step of introducing the steam into the at least one suppression tank comprises introducing the gas/steam mixture from the containment structure at a level selected to transfer a first portion of the water in the at least one suppression tank to the flood-up cavity leaving a remaining portion of the water in the at least one suppression tank for selective transfer to the reactor pressure vessel by gravity. claim 4 6. The method of claim 1 including disposing the lower portion of the reactor pressure vessel containing the reactor core in a flood-up cavity in the containment structure and including at least one suppression tank in the containment structure, introducing steam in the containment structure resulting from the loss coolant accident and gas in the containment structure into the water in the at least one suppression tank to condense the steam, and selectively using the gas in the at least one suppression tank, compressed during the condensing of steam by the gas added from the containment structure, to passively transfer water from the at least one suppression tank to the flood-up cavity. claim 1 7. The method of claim 6 further including constructing the containment structure from steel and directing a flow of a cooling fluid over an external surface of the containment structure to provide diverse cooling and depressurization of the containment structure whereby steam is condensed on the internal surface of the containment structure and returns to the reactor vessel flood-up cavity where it is available for cooling the reactor core. claim 6 8. The method of claim 1 including: claim 1 selectively venting steam from an upper portion of the reactor pressure vessel into the containment structure to ensure equalization of reactor pressure vessel pressure and containment structure pressure at a rate such that following a break in a lower portion of the reactor pressure vessel, reactor pressure vessel water level does not fall below the top of the reactor core. 9. The method of claim 1 including: claim 1 disposing a lower end of the reactor pressure vessel containing the reactor core in a flood-up cavity in the containment structure; providing a supply of water in the containment structure to fill the flood-up cavity to a level above the top of the reactor core; and selectively transferring water from the flood-up cavity to the reactor pressure vessel above the reactor core by gravity. 10. A method of operating a pressurized water reactor having a containment filled with an incondensable gas and containing an integral reactor comprising at least one steam generator mounted together with a reactor core in a pool of reactor coolant in a reactor pressure vessel, the method comprising: including at least one suppression tank containing water in the containment structure; and in response to a loss of coolant accident, introducing the incondensable gas in the containment structure together with steam in the containment structure resulting from the loss of coolant accident into the water in the at least one suppression tank to condense the steam and compress the incondensable gas; and selectively transferring water from the at least one suppression tank to the reactor pressure vessel to keep the reactor core covered with water by reducing pressure in the reactor pressure vessel by removing heat directly from the reactor pressure vessel to outside the containment structure thereby lowering pressure in the containment structure and allowing the compressed incondensable gas; in the suppression tank to push the water from the suppression tank into the reactor pressure vessel. 11. The method of claim 10 wherein the step of including at least one suppression tank comprises mounting the at least one suppression tank within the containment structure above the reactor core, and the step of selectively transferring water comprises selectively transferring water from the at least one suppression tank to the reactor pressure vessel by gravity. claim 10 12. A method of operating a pressurized water reactor having a containment structure filled with an incondensable gas and containing an integral reactor comprising at least one steam generator mounted together with a reactor core in a pool of reactor coolant in a reactor pressure vessel, the method comprising: disposing a lower portion of the reactor pressure vessel containing the reactor core in a flood-up cavity in the containment structure; including at least one suppression tank containing water in the containment structure; and in response to a loss of coolant accident, introducing the incondensable gas in the containment structure together with steam in the containment structure resulting from the loss of coolant accident into the water in the at least one suppression tank to condense the steam and compress the incondensable gas; and selectively transferring water from the suppression tank to the flood-up cavity by reducing pressure in the reactor pressure vessel by removing heat directly from the reactor pressure vessel to outside the containment structure thereby lowering pressure in the containment structure and allowing the compressed incondensable gas in the suppression tank to push water from the suppression tank into the flood-up cavity. 13. The method of claim 12 including transferring some of the water in the at least one suppression tank into the reactor pressure vessel. claim 12 14. The method of claim 13 wherein the at least one suppression tank is mounted in the containment structure above the reactor core and some of the water in the at least one suppression tank is transferred into the reactor pressure vessel by gravity. claim 13 15. The method of claim 14 wherein the incondensable gas and steam from the containment structure are introduced into the water in the at least one suppression tank at a level in the at least one suppression tank to transfer a selected amount of the water to the flood-up cavity using the incondensable gas compressed during the condensing of the steam in the at least one suppression tank and leaving a remaining amount of water in the at least one suppression tank for selective transfer by gravity to the reactor pressure vessel. claim 14
	description	The present invention relates to a container for radioactive materials such as waste or exothermic nuclear materials, the container being essentially constituted by a main hollow body inside which the radioactive materials are to be contained, as well as a cover for the main hollow body. In addition, the invention likewise relates to a process for closing such a container. The invention has particular application in the fields of nuclear waste treatment and conditioning. In this particular technical domain, several examples have already been put forward. Containers for radioactive materials whereof the main hollow body and the cover are assembled by welding are known in particular. If this technique employed remains satisfactory overall for containers made of standard steel or stainless steel, it is not however adapted to containers made of cast iron, this material however often being retained because of the possibility of its being obtained by recycling of very slightly contaminated metallic elements, originating from the dismantling of nuclear plants. In fact, only weld seams of slight thicknesses, namely not exceeding 5 to 6 mm, can be envisaged on cast iron. In general, the constraints on conditioning radioactive materials impose a weld seam which extends over the full thickness of the container, which is usually between around 30 and 130 mm. In addition, even in the case where welding is carried out on materials reputed to have good welding properties, the weld seams obtained on thicknesses such as those mentioned hereinabove are the seat of significant residual constraints, and these can be prejudicial to the durability of the container. In such a case, thermal detensioning treatments carried out at the same time as processes for conditioning waste nuclear are also carried out would be difficult to realise, and not totally efficacious on major thicknesses of the container wall. In the prior art, it has likewise been proposed to interpose a metallic joint between the cover and the main hollow body assembled by screw-bolt joint, the joint being designed so a to present satisfactory technical characteristics for a limited duration, of the order of some decades. Nevertheless, apart from the existence of a constraint in limitation over time of such a metallic joint, this solution proves to be little effective when the container is stored in a corrosive environment. In fact, the thickness of material available at the face of the corrosion front is minor, and considerably reduces the period during which acceptable tightness is conserved between the cover and the main hollow body of the container. To rectify the abovementioned disadvantages, the applicant has finally proposed a container made of cast iron comprising a cover fixed by sealing on the main hollow body, by projection of melted lead into a groove formed by the cover and the main hollow body of this container. When such a technique as described in the document FR-A-2 733 966 is made use of, the poured lead solidifies in the groove provided for this purpose, and forms a fixing element connecting the two main components of the container. It should be noted that connecting these elements originates essentially from the particular geometry of the groove, presenting at the level of the main hollow body a lateral surface in two portions inclined relative to the vertical according to acute and opposite angles, so as to create a corner effect preventing the cover from detaching from the main hollow body. However, it has been noticed that with such an arrangement, the mechanical bond obtained between the cover and the main hollow body of the container was not fully satisfactory, thus causing doubts as to the presence of a perfect tight fit between these two elements, and as a consequence doubts concerning the presence of secure isolation of the radioactive materials inside the container. In addition, the resulting lead joint is in no way adapted to support high temperatures, and cannot consequently enable storage of exothermal nuclear materials. In fact, since the melting temperature of the lead is only 327° C., this value then serves as a limit not to be exceeded for keeping mechanical contact between the two main elements constituting the container, this value even being able to be reduced in terms of the strong drop in mechanical characteristics of the lead beyond a certain temperature. The aim of the invention is thus to propose a container for radioactive materials comprising a main hollow body as well as a cover made of at least a first metallic material, the container at least partially rectifying the disadvantages mentioned hereinabove relative to the embodiments of the prior art. More precisely, the aim of the invention is to present a container whereof the mechanical bond and tight fit between the cover and the main hollow body are considerably improved relative to the solutions already proposed. In addition, the aim of the invention is to propose a process for the closing of such a container. To achieve this, the object of the invention first of all is a container for radioactive materials comprising a main hollow body as well as a cover made of at least a first metallic material, the cover capable of being fixed on the main hollow body by means of sealing means made of a second metallic material poured into a groove defined by the cover and the main hollow body of the container. According to the present invention, the cover and the main hollow body are attached to the sealing means by means of a bonding zone, formed by chemical reaction between the first and second metallic materials. Advantageously, the essential characteristic of the invention according to which the second metallic material poured into the groove is capable of reacting chemically with each first metallic material, allows the formation of a bonding zone constituted by intermetallic compounds ensuring a tight veritable metallurgic bond between the sealing means on the one hand, and the cover and the main hollow body of the container on the other hand. The reliability of the close contact of the cover on the main hollow body of the container is thus largely augmented, especially relative to the solution described in the document FR-A-2 733 966. In fact, the sealing means provided in this prior art take the form of lead poured into a groove made of cast iron, the latter using a specific geometry ensuring the cover is kept in place on the main hollow body, when the lead is set in the groove. Now, contrary to the container according to the invention, no chemical reaction is produced between the lead and the cast iron due to the inexistence of iron-lead intermetallic compounds, this property therefore prohibiting the presence of this type of compound at the interface between the sealing means and the groove. As a consequence, since no rigid metallurgic bond is provided between the sealing means on the one hand and the cover and the main hollow body of the container on the other hand, the bond obtained between the cover and the main hollow body is not in a position to offer acceptable mechanical resistance, nor even durable tightness between these two main elements of the container. Each first metallic material is preferably of the cast iron or steel type. In this manner, the second metallic material can be cast iron, zinc or one of its alloys, steel, or even aluminium or one of its alloys. In such cases, the bonding zone can then be made up of alloys of the iron-carbon, iron-zinc or iron-aluminium type, these materials being capable of ensuring perfect mechanical resistance between the sealing means and the two main elements making up the container. In addition, it is specified that the metallic materials indicated hereinabove, capable of being employed for making the sealing means, advantageously utilising a melting temperature higher than that of the lead utilised in the prior art, and are consequently capable of supporting the presence of exothermal radioactive materials inside the container. In addition, it is likewise specified that even if certain materials such as zinc and its alloys utilise a sufficiently high melting temperature to allow the storage of exothermal radioactive materials, the value of this temperature all the same advantageously allows relatively easy reopening of the cover, by means of classic means capable of causing fusion of the sealing means. According to a preferred embodiment of the present invention, the bonding zone has an average thickness of between around 10 μm and 5 mm, such that the mechanical bond engendered between the cover and the main hollow body of the container is durably resistant and tight. To increase this bond even more, it is possible to provide that the cover comprises an external lateral surface partially defining the groove and comprising two adjacent portions inclined respectively at an angle α and an angle β relative to a direction parallel to a longitudinal principal axis of the container, the angles α and β being acute and opposite in order to obtain a corner effect. On the other hand, the object of the invention is likewise a process for closing a container for radioactive materials comprising a main hollow body as well as a cover made of at least a first metallic material, the process comprising a stage of placing the cover on the main hollow body of the container so as to form a groove between these two elements, followed by a stage of making sealing means ensuring fixation of the cover on the main hollow body of the container by pouring a second metallic material into the groove. According to the invention, the second metallic material is selected such that it is likely to react chemically with each first metallic material, so as to form a bonding zone between the sealing means on the one hand, and the cover and the main hollow body of the container on the other hand. The stage of placing the cover is preferably followed by a stage pre-heating the first material constituting the groove, this latter stage likewise able to be preceded by preparation of the surfaces of the groove. In addition, it is possible to provide that the stage of making the sealing means is preceded by a stage of excess pouring of the second metallic material into the groove over a predetermined period, so as to cause heating of the first metallic material constituting the groove, as well as washing the surfaces of this groove. The stage of making the sealing means by pouring the second metallic material into the groove is preferably followed by a heating stage of this second material resting in the groove, so as to favour chemical reaction between the first and second metallic materials. Other advantages and characteristics of the invention will emerge from the following detailed non-limiting description. With reference to FIGS. 1 and 2, they illustrate partially and schematically a container 1 for radioactive materials, according to a preferred embodiment of the present invention. In these figures, only a part of the upper portion of the container 1 is visible, this container 1 being substantially cylindrical in shape and having a circular cross-section, but of course able to take on any other form compatible with the technical field in question. The container 1 comprises a main hollow body 2, defining a space 4 inside which can be housed the radioactive materials, such as exothermal nuclear waste. In addition, the container 1 comprises a cover 6 capable of being encased by the main hollow body 2, so as to obtain a fully closed space 4. The space 4, preferably circular in cross-section, is delimited on the one hand by means of a lateral surface 8 and a base (not shown) formed by the main hollow body 2, and on the other hand by means of an upper surface 10 formed by the cover 6, the latter as well as the main hollow body 2 being arranged in coaxial fashion. As is visible in FIGS. 1 and 2, the main hollow body 2 and the cover 6 respectively utilise annular contact surfaces 12 and 14, allowing of the cover 6 relative to the main hollow body 2 to be stopped in translation, during encasing of these two elements 2 and 6. In addition, the contact surfaces 12 and 14 are preferably conceived such that the cover 6 can be lodged in the main hollow body 2 without projecting beyond the latter, and that their respective upper surfaces 13 and 15 are situated substantially in the same plane perpendicular to a longitudinal principal axis (not illustrated in these figures) of the container 1. Of course, it is possible to provide clearance 16 between the lateral surface 8 of the space 4 and a cylinder 18 constituting the lower part of the cover 6, so as to facilitate introduction of this cover 6 into the main hollow body 2 of the container 1. By way of example, the clearance 16 can be of the order of 0.5 mm. More specifically in reference to FIG. 1, on which the container 1 is illustrated while the cover 6 has not yet been fixed on the main hollow body 2, the latter presents in its upper portion an internal lateral surface 20, whereas the cover 6 presents an external lateral surface 22. When the cover 6 is put in place on the main hollow body 2, the lateral 20 and adjacent 22 and continuous surfaces form a groove 24 extending preferably all around the longitudinal principal axis of the container 1 according to a variable horizontal section, this groove 24 being open to the exterior of this container 1. It is specified that the groove 24 could naturally extend only partially around the longitudinal principal axis of the container 1, for example to form portions of angularly spaced grooves, without going beyond the scope of the invention. By the same token, note that the groove 24 can likewise be made so as to utilise a constant horizontal section, the form of this groove being easily modulated, by simple adaptation of the internal lateral surface 20 and of the external lateral surface 22. The resulting groove 24 allows a space to open up in which sealing means 26 (shown in FIG. 2) will allow the cover 6 to be sealed onto the main hollow body 2 of the container 1. In reference to FIG. 2, in which the container 1 is illustrated in a closed and fixed state, it is evident that the sealing means 26, previously poured into the groove 24 provided initially between the cover 6 and the main hollow body 2, have been introduced to this groove 24 so as to occupy the entirety of the space defined by this groove. In addition, when the sealing means 26 are in a set state such as that illustrated in FIG. 2, the surfaces 20 and 22 of the groove 24 are no longer apparent (but all the same sketched in dotted lines to facilitate comprehension), and the sealing means 26 are no longer in direct contact with the cover 6 and the main hollow body 2. In fact, the cover 6 and the main hollow body 2 on the one hand, and the sealing means 26 on the other hand, are separated by a bonding zone 28, having a form substantially identical to that of the wall of the groove 24 initially provided, over a thickness 29 ranging from 10 μm to 5 mm, and being preferably of the order of 2 mm. The bonding zone 28, situated substantially at the initial placement of the external lateral surface 22 and of the internal lateral surface 20, results from a chemical reaction produced between the cover 6 and the main hollow body 2 on the one hand, and the sealing means 26 on the other hand, during pouring of the sealing means 26 into the groove 24. In this way, the bonding zone 28 ensures a rigid mechanical bond between the sealing means 26 and the two main elements 2 and 6 of the container 1, this specificity of the invention ensuring perfect tightness of the container. To produce the bonding zone 28 by chemical reaction, the main hollow body 2 and the cover 6 are made of at least a first metallic material, and preferably of the same material such as steel or cast iron. In addition, the sealing means 26 are made of a second metallic material, such as cast iron, zinc or one of its alloys, steel, aluminium or one of its alloys, or again any other metallic material capable of having reactivity with the first metallic material, so as to react chemically with the latter and constitute a bonding zone 28 comprising intermetallic compounds. Accordingly, by way of non-limiting example, when the cover 6 and the main hollow body 2 are made of steel and when the sealing means 26 are made of cast iron, these two materials are likely to react with one another when the cast iron is still liquid, so as to form a bonding zone 28 composed of a iron-carbon alloy, obtained by diffusion of the carbon of the cast iron to steel. Once the chemical reaction is completed and the sealing means 26 are set, the bonding zone 28 has a carbon gradient in a direction going from the sealing means 26 towards the cover 6 or the main hollow body 2 of the container 1, and the structure of this bonding zone 28 evolves from a mixture of de ferrite and perlite to cast iron, passing through a structure of eutectoid then hyper-eutectoid steel. In the same way and still by way of example, when the sealing means 26 comprise zinc or aluminium, the bond zones 28 obtained are respectively composed of an iron-zinc alloy and an iron-aluminium alloy, ensuring rigid mechanical contact between the sealing means 26 and the two main elements 2 and 6 of the container 1. In addition, in the case of the use of zinc or one of its alloys, it has been noted that the bonding zone 28 had a structure similar to that observed in the case of galvanisation operations carried out by soaking steel elements in liquid zinc. Finally, a last example relates to the case where the first and second materials are made of steel, the latter being selected such that carbon diffusion is possible when the sealing means 26 are in the liquid state, to produce a bonding zone 28 of iron-carbon alloy having a carbon gradient in a direction going from the sealing means 26 to the cover 6 or the main hollow body 2 of the container 1. In order to even more reinforce fixing the cover 6 onto the main hollow body 2 of the container 1, it is possible to adapt the initial geometry of the groove 24, formed by the lateral internal surface 20 and the lateral external surface 22. To this end, and in reference to FIG. 1, the external lateral surface 22 of the cover 6 may comprise two adjacent portions 30 and 32 inclined respectively at an angle α and at an angle β relative to a direction 34 parallel to the longitudinal principal axis of the container 1, the angles α and β being acute and opposite to produce a corner effect when it is intended to extract the cover 6 from the main hollow body 2. As can be seen in FIG. 1, the upper portion 32 is inclined so as to close in on the longitudinal principal axis by moving away towards the upper portion of the container 1, while the lower portion 30 is inclined so as to close in on the longitudinal principal axis by moving away towards a lower portion of the container 1. In addition, it should be noted that the internal lateral surface 20 of the main hollow body 2 can likewise comprise a portion 36 inclined in the same manner as the upper portion 32 of the external lateral surface 22, namely so as to move towards the longitudinal principal axis by moving away towards the upper portion of the container 1, this portion 36 being preferably opposite the upper portion 32 of the external lateral surface 22. Therefore, when the sealing means 26 take their place in the groove 24, the part of these sealing means 26 located between the initially provided portions 32 and 36, substantially takes the form of a cap ensuring supplementary mechanical contact by the cover 6 on the main hollow body 2. Naturally, the form of the groove 24 can be conceived in any other manner aiming to provide a geometry ensuring contact by the cover 6 on the main hollow body 2, when the sealing means 26 are set inside this initially provided groove 24, without going beyond the scope of the invention. And finally, it should be noted that the groove 24 has a variable width, capable of extending for example between 10 and 20 mm, and being of the order of 15 mm at the portions 32 and 36 opposite. The invention likewise relates to a process for closing the container, such as that which has just been described hereinabove. According to a first preferred embodiment of the process according to the invention which will be described hereinbelow, the first metallic material selected for making the cover 6 and the main hollow body 2 is steel, for example of type E24, whereas the second poured metallic material employed for forming the sealing means 26 is cast iron, for example of type EN-GJS-400-15. The first stage of this process consists of placing the cover 6 onto the main hollow body 2 of the container 1, so as to form the groove 24, as is evident in FIG. 1. While this process is being performed, it is then preferable to carry out a stage for preparation of the surfaces of the groove 24, namely the internal lateral surface 20 of the main hollow body 2 and the external lateral surface 22 of the cover 6. To do this, several solutions are possible. In fact, the surfaces 20 and 22 can be prepared by means of a mechanical technique such as sanding, a chemical technique such as degreasing or pickling, an electrochemical technique or again by depositing a layer of metallic material such as zinc or nickel. By way of example, the surfaces 20 and 22 of the groove 24 can be nickel-plated to prevent oxidation of these surfaces as their temperature rises and in the presence of air. In addition, the techniques possible for depositing the layer of metallic material are taken from among classic techniques for metallic depositing, such as galvanisation for depositing zinc. Of course, the stage for preparation of the surfaces 20 and 22 of the groove 24 can consist on the combination of several of the techniques mentioned hereinabove. Once preparation of the surfaces 20 and 22 of the groove 24 is completed, these surfaces 20 and 22 can then undergo a low-temperature pre-heating stage to prevent their oxidation, for example of the order of 400° C., by means of electric heating collars or any other means ensuring such a function. It should be noted that this operation can be carried out under neutral gas to totally avoid the harmful effects which oxidation of the surfaces 20 and 22 of the groove 24 might cause. The next step is the process of pouring the cast iron into the groove 24, so as to form the sealing means 26 shown in FIG. 2. In reference to FIG. 3, a possible arrangement for performing the pouring off the second metallic material in the groove 24 is illustrated, the latter being annular and having an axis identical to the longitudinal principal axis 38 of the container 1. As is evident from this figure, means for pouring the cast iron 40, assembled on the cover 6 of the container 1, comprise a receptacle 42 in which is situated the cast iron in the liquid state. The receptacle 42 is mounted to pivot on a support 44 solid with the end of an arm 46, the latter being able to pivot about the longitudinal principal axis 38 of the container 1. The liquid cast iron remaining in the receptacle is capable of being poured out into an orifice having the form of d'un funnel 48, likewise mounted on the arm 46 of the means 40. The funnel 48 communicates with an evacuation conduit 50, whereof the end 52 is oriented close to and opposite the groove 24. It should be noted that the funnel 48 is also able to pivot according to an axis parallel to the axis of rotation between the receptacle 42 and the support 44, this specificity being provided so as to ensure clean discharge of the liquid cast iron into the funnel 48, irrespective of the quantity of cast iron present in the receptacle 42. On the contrary, the rotations of the elements 42 and 48 relative to the support 44 can be made manually, respectively by means of by means of handles 54 and 56. Thus, by having the arm 46 pivot about the axis 38, the end 52 of the cast iron evacuation conduit 50 can describe a circular movement allowing it to be constantly opposite the base of the groove 24, this specific characteristic thus ensuring the possibility of take advantage of uniform distribution of the cast iron inside this groove 24, during the pouring operation. In this first preferred embodiment of the process according to the invention, the cast iron is then poured into the groove 24, for example at a temperature approaching 1470° C. As has been indicated, the pouring of the cast iron is carried out by putting the arm 46 of the means 40 in rotation about the longitudinal principal axis 38, indifferently manually or automatically. Before the completed pouring is directly intended to form the sealing means 26, the cast iron can be poured in excess and continuously, to heat and wash the surfaces 20 and 22 of the groove 24, nickel-plated beforehand. A system for recovery of the supernatant cast iron (not shown) can then consist of means for evacuation of the cast iron situated at the bottom of the groove 24, or again means arranged on the surface for recovering the cast iron overflowing from this groove. The pouring of cast iron in excess over a determined period thus eliminates the impurities present in the groove 24, and rapidly dissolves the layer of nickel deposited on the surfaces 20 and 22, in the aim of obtaining clean surfaces made of steel 20 and 22 allowing good chemical reaction with the cast iron. The period of pouring in excess can especially be determined as a function of the optimal temperature to be reached for the surfaces 20 and 22 of the groove 24, thus by taking into consideration diverse parameters such as the superficial area of these surfaces 20 and 22, the rate of cast iron, the temperature of the cast iron, etc. In addition, it is noted that this period can also depend on the thickness of the metallic deposit previously made on the surfaces 20 and 22 of the groove 24. Typically, for a total surface of the groove 24 of around 400 cm2, the filling time is around 40 seconds and the quantity of cast iron poured in excess for the washing and heating is of the order of 250 kg, or a rate of washing of 0.06 kg/s.cm2. When the sealing means are poured into the groove 24 and the heating and washing operations of this groove 24 are complete, an ultimate stage consists of heating the cast iron such that it remains liquid in the groove 24. The main aim of this stage is to favour diffusion of the carbon from the cast iron of the sealing means 26, to steel of the main hollow body 2 and of the cover 6 of the container 1. The diffusion of carbon then produces a bonding zone 28 of iron-carbon alloy, ensuring a tight mechanical bond, directly between the sealing means 26 on the one hand, and the main hollow body 2 and the cover 6 on the other hand. This heating stage of the cast iron in the groove 24 can be performed by way of classic heating such as electric heating collars (not shown), at a temperature of the order of 500° C. for around 2 hours. It is specified that the duration of heating can be adapted so that the chemical reaction between the first and second metallic materials is completed, or so that the bonding zone 28 is sufficiently important to generate a perfect and tight mechanical bond between the cover 6 and the main hollow body 2 of the container 1. As mentioned hereinabove in the description of the container 1, the bonding zone 28, obtained as a result of utilising such a process, has a microstructure evolving on a thickness 29 of around 2 mm, from a mixture of ferrite and perlite to cast iron, by passing through a structure of eutectoid then hyper-eutectoid steel. Tests have shown that the bonding zone 28 had a resistance to breaking of around 276 MPa, for an elasticity limit of 146 MPa at 0.2%, and breaking elongation of the order of 33.1%. In a second preferred embodiment of the process according to the invention, when the second metallic material is selected from among zinc and its alloys and when the first metallic material is from steel, the surfaces 20 and 22 of the groove 24 do not undergo preparation via metallic deposit such as nickel, but are dipped so as to obtain surfaces 20 and 22 capable of reacting easily with the poured zinc. The other stages of the process are carried out substantially in the same way as those mentioned in the first preferred embodiment of the invention, with the difference that zinc is poured around 470° C., and that the post-poured heating is maintained at 500° C. for 4 hours. After setting of the second metallic material, the bonding zone 28 is composed of an iron-zinc alloy, substantially identical to that obtained during galvanisation carried out by soaking steel pieces in liquid zinc. Additionally and in general, irrespective of the first metallic material retained, the use of zinc or of one of its alloys as second metallic material is advantageous in the sense that the reopening of the cover 6 can be easily envisaged by fusion of the sealing means 26, in terms of the low melting temperature of this type of material. According to a third preferred embodiment of the process according to the invention, when the second metallic material is selected from among aluminium and its alloys and when the first metallic material remains from steel, the stages are similar to those described previously in the two first preferred embodiments, with the difference that the pouring stage is preferably carried out under protection of a neutral gas. These specific operating conditions allow work to be carried out under an oxidising atmosphere, and consequently prohibit the formation of a layer of aluminium on the surfaces 20 and 22 of the groove 24, which would be strongly prejudicial to the chemical reaction between the iron and aluminium, and thus to the mechanical performances of the bonding zone 28. Finally, it is specified that the reopening of the cover 6 sealed on the main hollow body 2 of the container 1 can easily be carried out by fusion of the sealing means 26. This fusion is carried out preferably by means of heating by torch, laser, induction or by resistors. Of course, various modifications can be made by the specialist to the container 1 for radioactive materials and to the process for closing such a container which has just been described hereinabove, only by way of non-limiting examples.
051035049	claims	1. A textile clothing fabric comprising orthogonal crossings between warp threads and weft threads, the threads being made of stainless steel fibers and textile fibers blended together and spun into mixed yarn, wherein the textile fibers comprise cotton fibers and are twined with the steel fibers, the steel fibers measure 6 to 10 micrometers in diameter and constitute a content of 10 to 15% per weight of the mixed yarn, the distribution of the warp threads and the weft threads in the fabric and the composition of the warp threads and the weft threads being substantially the same, the number of mixed yarn threads in warp direction and in weft direction each is 18 to 20 threads per cm, the yarn fineness of the textile fabric is in the range of 30 to 50 tex, a part of the steel fibers is exposed on the exterior surface of the mixed yarn and mutual electrical contact exists between the warp and weft threads at said crossings to form a Faraday cage, such that a shielding by 20 to 40 dB against electromagnetic radiation at a frequency of 10 GHz is established by the fabric. 2. The textile fabric of claim 1, wherein the mixed yarn is made of double-twined mixed yarn threads comprised of two twined single threads, each of which is made of textile fibers and steel fibers in a twined manner, wherein the single threads have a yarn fineness of 16 to 20 tex and a degree of turns of 550 to 650 turns per m, and wherein the degree of turns of the double-threads is 400 to 480 turns per m. 3. The textile fabric of claim 1, wherein the fiber thickness of the steel fibers measured 8 micrometers, and the content of the steel fibers in the mixed yarn is 13.5% per weight of the mixed yarn. 4. The textile fabric of claim 1, wherein the length of the steel fibers is 3 to 10 micrometers. 5. The textile fabric of claim 1, wherein the textile fibers are made only of cotton. 6. The textile fabric of claim 1, wherein the weight of the textile fabric is 130 to 190 g per m.sup.2. 7. Clothing for a human wearer, the clothing being completely or partly made of one piece of textile clothing fabric, the clothing being constructed to cover at least an upper part of the body and a hip area of the wearer, and further comprising a neck-chest area and sleeves, the piece of textile fabric comprising fabric parts sewed together along joint seams and being adapted to be opened and closed by means of a fastener at least in the neck-chest area, characterized in that the textile clothing fabric has the features of any of claim 1 to 6, the sleeves being at least elbow-length, the joint seams being turned up into each other and sewed together by at least two seams of sewing yarn composed of the mixed yarn, the fastener being free of metal and being underlaid with an interior border band or flap of the textile clothing fabric having a breadth of at least 5 centimeters. 8. The clothing of claim 7, wherein the textile fabric is provided with pickets made of a cloth sewed onto said textile clothing fabric. 9. The clothing of claim 7, wherein the clothing further comprises a T-shirt having elbow-length sleeves and is made of steel fibers and textile fibers. 10. The clothing of claim 7, wherein the clothing further comprises a one-piece overall having a stand-up collar and wherein the textile fabric covers the legs of the wearer at least down to the knees. 11. The clothing of claim 7, wherein the clothing is comprised of a jacket and trousers, and wherein the trousers are overlapped by the jacket by at least 10 centimeters, and the jacket or blouse, has at least first and second textile fabric parts overlapping each other and being held together by fasteners connecting the textile fabric parts with each other. 12. The clothing of claim 11, wherein the first overlapping textile fabric part extends to one shoulder of the wearer, and the second textile fabric part extends at least to the middle of the body when the jacket is closed. 13. The clothing of claim 11, wherein adjustability of a waist portion of the trousers is provided by means of fasteners made of plastic material. 14. The clothing of claim 11, wherein the jacket has a stand-up collar made of the fabric of steel fibers and textile fibers.
063234971	abstract	A method and apparatus for controlling implantation during vacuum fluctuations along a beam line. Vacuum fluctuations may be detected based on a detected beam current and/or may be compensated for without measuring pressure in an implantation chamber. A reference level for an ion beam current can determined and a difference between the reference value and the measured ion beam current can be used to control parameters of the ion implantation process, such as a wafer scan rate. The difference value can also be scaled to account for two types of charge exchanging collisions that result in a decrease in detected beam current. A first type of collision, a non-line of sight collision, causes a decrease in detected beam current, and also a decrease in the total dose delivered to a semiconductor wafer. A second type of collision, a line of sight collision, causes a decrease in detected beam current, but does not affect a total dose delivered to the wafer. Scaling of the difference can therefore be used to adjust a wafer scan rate that accounts for non-line of sight collisions.
	claims	1. A method for removing radioactive cesium applying removing processing to radioactive cesium in a radioactive waste liquid and/or a radioactive solid matter using a hydrophilic resin composition comprising a hydrophilic resin and a metal ferrocyanide compound,wherein the hydrophilic resin composition comprises at least one hydrophilic resin selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 2. A method for removing radioactive cesium applying removing processing to radioactive cesium present in a radioactive waste liquid and/or a radioactive solid matter using a hydrophilic resin composition comprising a hydrophilic resin and a metal ferrocyanide compound,wherein the hydrophilic resin comprises at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment and further each having, in the main chain and/or a side chain in the structure thereof, a polysiloxane segment; andthe hydrophilic resin composition comprises the metal ferrocyanide compound dispersed therein in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 3. The method for removing radioactive cesium according to claim 2,wherein the hydrophilic resin is a resin formed from, as a part of a raw material, a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule. 4. The method for removing radioactive cesium according to claim 1,wherein the hydrophilic segment is a polyethylene oxide segment. 5. The method for removing radioactive cesium according to claim 1,wherein the metal ferrocyanide compound is a compound represented by the following general formula (1):AxMy[Fe(CN)6] (1)[in the formula, A is any one selected from K, Na, and NH4, M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, x and y satisfy an equation x+ny=4 (x is an integer from 0 to 3), and n represents a valence number of M]. 6. A hydrophilic resin composition for removing radioactive cesium exhibiting a function capable of immobilizing radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is at least one resin selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment and each obtained by reacting an organic polyisocyanate with a high-molecular weight hydrophilic polyol and/or polyamine being a hydrophilic component, the resin being insoluble to water and hot water; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 7. The hydrophilic resin composition for removing radioactive cesium according to claim 6, wherein the hydrophilic segment of the hydrophilic resin is a polyethylene oxide segment. 8. The hydrophilic resin composition for removing radioactive cesium according to claim 6,wherein the metal ferrocyanide compound is a compound represented by the following general formula (1):AxMy[Fe(CN)6] (1)[in the formula, A is any one selected from K, Na, and NH4, M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, x and y satisfy an equation x+ny=4 (x is an integer from 0 to 3), and n represents a valence number of M]. 9. A hydrophilic resin composition for removing radioactive cesium exhibiting a function capable of immobilizing radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is a resin having a hydrophilic segment and a polysiloxane segment and obtained by reacting, as a part of a raw material, a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule, the resin being insoluble to water and hot water; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 10. A hydrophilic resin composition for removing radioactive cesium exhibiting a function capable of immobilizing radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment, further each having, in the main chain and/or a side chain in the structure thereof, a polysiloxane segment, and each obtained by reacting an organic polyisocyanate, a high molecular weight polyol and/or polyamine being a hydrophilic component, and a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 11. A method for removing radioactive iodine and radioactive cesium applying removing processing to both of radioactive iodine and radioactive cesium present in a radioactive waste liquid and/or a radioactive solid matter using a hydrophilic resin composition comprising a hydrophilic resin and a metal ferrocyanide compound,wherein the hydrophilic resin comprises at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment and further each having, in the main chain and/or a side chain in the structure thereof, a tertiary amino group; andthe hydrophilic resin composition comprises the metal ferrocyanide compound dispersed therein in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 12. The method for removing radioactive iodine and radioactive cesium according to claim 11,wherein the hydrophilic resin is a resin formed from, as a part of a raw material, a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group. 13. The method for removing radioactive iodine and radioactive cesium according to claim 11, wherein the hydrophilic segment is a polyethylene oxide segment. 14. The method for removing radioactive iodine and radioactive cesium according to claim 11,wherein the metal ferrocyanide compound is a compound represented by the following general formula (1):AxMy[Fe(CN)6] (1)[in the formula, A is any one selected from K, Na, and NH4, M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, x and y satisfy an equation x+ny=4 (x is an integer from 0 to 3), and n represents a valence number of M]. 15. A method for removing radioactive iodine and radioactive cesium applying removing processing to both of radioactive iodine and radioactive cesium present in a radioactive waste liquid and/or a radioactive solid matter using a hydrophilic resin composition comprising a hydrophilic resin and a metal ferrocyanide compound,wherein the hydrophilic resin comprises at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment and further each having, in the main chain and/or a side chain in the structure thereof, a tertiary amino group and a polysiloxane segment; andthe hydrophilic resin composition comprises the metal ferrocyanide compound dispersed therein in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 16. The method for removing radioactive iodine and radioactive cesium according to claim 15, wherein the hydrophilic resin is a resin formed from, as a part of a raw material, a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group and a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule. 17. A hydrophilic resin composition for removing radioactive iodine and radioactive cesium exhibiting a function capable of immobilizing both of radioactive iodine and radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is a resin having a hydrophilic segment, having, in the molecular chain, a tertiary amino group, and formed from, as a part of a raw material, a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group, the resin being insoluble to water and hot water; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 18. The hydrophilic resin composition for removing radioactive iodine and radioactive cesium according to claim 17, wherein the hydrophilic segment of the hydrophilic resin is a polyethylene oxide segment. 19. The hydrophilic resin composition for removing radioactive iodine and radioactive cesium according to claim 17,wherein the metal ferrocyanide compound is a compound represented by the following general formula (1):AxMy[Fe(CN)6] (1)[in the formula, A is any one selected from K, Na, and NH4, M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, x and y satisfy an equation x+ny=4 (x is an integer from 0 to 3), and n represents a valence number of M]. 20. A hydrophilic resin composition for removing radioactive iodine and radioactive cesium exhibiting a function capable of immobilizing both of radioactive iodine and radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment, further each having, in the main chain and/or a side chain in the structure thereof, a tertiary amino group, and each obtained by reacting an organic polyisocyanate, a high molecular weight hydrophilic polyol and/or polyamine being a hydrophilic component, and a compound having at least one active hydrogen-containing group and at least one tertiary amino group in the same molecule; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 21. A hydrophilic resin composition for removing radioactive iodine and radioactive cesium exhibiting a function capable of immobilizing both of radioactive iodine and radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is a resin having a hydrophilic segment, having, in the molecular chain, a tertiary amino group and a polysiloxane segment, and formed from, as a part of a raw material, a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group and a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule, the resin being insoluble to water and hot water; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin. 22. A hydrophilic resin composition for removing radioactive iodine and radioactive cesium exhibiting a function capable of immobilizing both of radioactive iodine and radioactive cesium in liquid and/or a solid matter,wherein the hydrophilic resin composition comprises a hydrophilic resin and a metal ferrocyanide compound;the hydrophilic resin is at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin each having a hydrophilic segment, each having, in the main chain and/or a side chain in the structure thereof, a tertiary amino group and a polysiloxane segment, and each obtained by reacting an organic polyisocyanate, a high molecular weight hydrophilic polyol and/or polyamine being a hydrophilic component, a compound having at least one active hydrogen-containing group and at least one tertiary amino group in the same molecule, and a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule; andthe metal ferrocyanide compound is dispersed in the hydrophilic resin composition in a ratio of at least 1 to 200 mass parts relative to 100 mass parts of the hydrophilic resin.
051736128	abstract	An X-ray window having a diamond X-ray transparent film, diamond reinforcing crosspieces and a substrate on which the diamond X-ray transparent film has been grown. As reinforcing crosspieces are made of diamond, no thermal stress is generated between the X-ray transparent film and the crosspieces. This mask excels in flatness, transmittance of X-rays, and strength.
050842323	summary	The present invention provides: (1) The precise and the unique solution of a previously unsolved P.sub.2 targeting problem; (2) Impacts to the governmental NRC nuclear safety standards, DOD weaponary systems development and many other activities in NASA and in the Department of Energy; (3) Impacts to update the contents of text books of physics and mathematics of all levels for education; (4) Impacts to the designs of scientific intrumentations with applications in high technologies. In conclusion, the invention of TRAJECTORY SOLID ANGLE provides a revolutionary concept in the fundation of physics. It it is confirmed to be true, it will open a new era for researches in physics, mathematics, engineering, advanced instrumentations and scientific measurements. BACKGROUND OF THE INVENTION Back to 1974 and earlier, the U.S. Atomic Energy Commission (AEC) (now the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC) openly solicited the solution of an unsolved problem which can be equivalently stated as: TO DETERMINE AND DEFINE THE PROBABILITY FUNCTION P.sub.2 FOR A PARTICLE TO HIT A PREDESIGNATED AREA, GIVEN ALL ITS PARAMETERS OF GENERATION AND EJECTION. Responding to the solicitation to solve the problem, a committee of scientists, mathematicians, and engineers from many companies was formed. The companies included: Westinghouse, General Electric, Raytheon, Stanford Research Institute, . . . and many other companies. They produced many reports to solve the problem. Those reports were circulated from one company to the other for the participants to provide mutual reviews and feedbacks in order to obtain the TRUE solution. The inventor, working then in 1974 at Stone & Webster Engineering Co. in Boston, Mass., was also assigned to review and evaluate some of those reports. The inventor was also requested to provide his own solution of the problem in addition to the assignment of reviewing others' reports. As a result, the author invented in October 1974 a new physical term "TRAJECTORY SOLID ANGLE" (TSA) to solve the solicited problem. The TSA was a new name having been called by the inventor in order to identify for its difference from the very well-known Geometric Solid Angle (GSA). Before October 1974, there was no such name as (TSA) in the nomenclature of science and engineering. On the other hand, the Geometric Solid Angle (GSA) has been very well known to all. The original hand-written report in which the TSA was first invented has been kept and saved by the Stone & Webster Engineering Co. since October 1974. Only copies of this original work together with two other topics original work (muti-reservoir transient problems' formulation and solution, and the solution of indeterminate structural systems' problem) were returned to the inventor in early 1975 by Stone & Webster Engineering Co. when the inventor was separated from the company. All these can be seen from the evidences of a copy of the inventor's Mar. 29, 1975 letter to Mr. V. A. Suziedelis, Senior Engineering Manager and Vice President, Stone & Webster Engineering Co. and the inventor's Sept. 8, 1977 letter to Dr. Saul Levine, Director, Office of Nuclear Regulatory Research, Nuclear Regulatory Commission (NRC). These important letters can be found from the cited reference No. [17] which are documented with: (1) reponses to the review and comments about the paper 82-IHTC-86" ON THE INITIATION OF TRAJECTORY SOLID ANGLE AND ITS INFLUENCE TO RADIATIVE HEAT TRANSFER" in 1981; (2) reponses to the review from NRC about the TSA proposal; (3) responses to the U.S. Army Missile Research and Development Command's review about TSA; (4) responses to the U.S. Army Ballistic Research Laboratory of Aberdeen Proving Ground's review about TSA; (5) reponse to the review from Professor Walter Hauser of Northeastern University. The responses to the reviews for DOE proposal No. P7900450 (cited reference [7]) can be seen from cited reference No. [15]. As indicated in cited references [17] and [15], the TSA concept has been rejected from one agency to the other. It was enrouted for review from NRC to BRL to U.S. Army Misslie R&D Command; to National Science Foundation, AFSC-AFAL, AFSC-SAMSO, AFSC-AFOSR, AFSC-RADC, AFSC-AFGL, AFSC-ESD, EPRI, ERDA, JCM-20, SER 211/103 and back to DOE high energy physics division in Jan. 17, 1979 again. It was unfortunate that the reviewers from DOE rejected the proposal again and DOE advised that the inventor should send it to National Science Foundation for support. Again the reviewers of DAR of NSF rejected the proposal and it was transferred to the Physics Division of NSF. It is unfortunate that the reviewers rejected the proposal again. The continuous rejections to accept the concept of TSA by the Federal Agencies; Academic institutions; numerous scientific journals have forced the inventor to take two actions: (1) Formally file the patent of invention of TRAJECTORY SOLID ANGLE; (2) Openly challenge scientists in the 1989 AAAS Annual Meeting, Jan. 14-19, 1989 in San Francisco by sending the cited reference [19] to 11 session organizers; by presenting the TSA papers (cited reference [1] and [2]); by appearing himself in most of the related sessions to discuss what, why, how the TSA concept being important to them and that they have been taking the wrong track to solve their problems. The action of filing the TSA patent was advised by Dr. John Lyons, Director of Engineering, and Dr. George A. Sinnott, Associate Director of Technical Evaluation, both of National Bureau of Standards (NBS) in April 1985. As a result of their advices, the patent for the invention of TRAJECTORY SOLID ANGLE was initially filed in the attachments of an open letter dated Jan. 7, 1986 sent to the Commissioner of Patents and to the Executive Heads both in the Federal and State government of Mass. and to some members of the U.S. Congress. The action of open challenges to the scientists in the AAAS 1989 January Meeting have been done in last month. The TSA proposal is again submitted back to NSF for support. The current proposals pending supports from NSF are cited reference No.: [20], [21], [22]. Thus far, since the invention of the TRAKECTORY SOLID ANGLE by the inventor in October 1974, it has been continuously developed alone solely by the inventor. It has never been funded by any organizations; Federal; state; local and public. All the proposals and technical information, papers and data are strictly proprietary. SUMMARY OF THE INVENTION As indicated in the BACKGROUND OF THE INVENTION, the most relevant work proposed before 1974 in U.S.A. to solve the P.sub.2 targeting problem can be traced from the references of and the reports by Sermanderes [3], Bush [4], Shaffer et al [5], and by the partial notes [6] of a PSAR (Preliminary Safety Analysis Report) of Delmarva Power & Light Company Summit Stattion, April 1974. These four reports concentrated in solving the same example of the solicited targeting problem that is to find the probability function P.sub.2 for a ejected turbine missile to hit a predesignated area assuming it moves in vacuum and under a constant gravitation. A solution of this looks-like-a-simple problem was also proposed by the inventor [7] who was simultaneously assigned to make a detail technical review of those reports. As can be seen from the 20 pages hand-written summary that was in the proposal by the inventor [7], the Geometric Solid Angle (GSA) approach to solve the P.sub.2 targeting problem was discussed in the reports by Sermanderes [3] and by [6]. However, as indicated by the inventor at that time the Geometric Solid Angle (GSA) is only one of the very special case of the invented TRAJECTORY SOLID ANGLE (TSA). The (TSA) was invented without proof at that time making an analogy with the (GSA) that had been used for years for calculation of the scattering & collision cross-section of particles; radar scanning cross-sections; geometric shape factors in radiative heat transfer; and in optics. The (TSA) was invented in a mood of intant reflection at a critical time when the author was told to write a final report on the P.sub.2 targeting problem after he had been working and reviewing the work by others for a continuous period of three months. Even since then the (TSA) has been continuously developed alone by the inventor to examine its validity and truth in solving various kind of problems related to Statistical Mechanics despite of the confrontation and oppositions from all sources. After his separation from Stone & Webster Engineering Company, the inventor was forced to form SYSTEMS RESEARCH COMPANY in order to survive from being unemployed. The SYSTEMS RESEARCH COMPANY's Jan. 17, 1979 unsolicited proposal [7] had provided the various targeting problems having been solved and had indicated the approaches and research plans step by step through all the responses by the inventor to the mutual reviews and discussions with professionals in U.S. governmental, academic, and industrial organizations. It was and still is the current opinion of the inventor that a new statistical method has been found through the definition of (TSA). This new parametric statistics, being characterized and derived from fractional ratio or from the intersection and union of the acceptable laws of physics and the set theory of mathematics, is applicable for a macropic body as well as for a microscopic particle of mathematically defined infinitestimal size under the action of any force and moment fields. This new parametric statistics, being different from the usual consequential statistics or non-parametric statistics, could have been also the essential element that was missed by Einstein in his incomplete work for the unified field theory. With the precise definition of (TSA) and the definite procedures to find the probability function P.sub.2, the probability density function (pdf) for the particle hitting on a surface can be also determined. Thus the physical quantities like dynamic pressure, density, linear momentum, angular momentum and kinetic energy distribution of the particle at any location can also be obtained by integration of the product of the physical quantity with the (pdf) over the predesignated area. This is a standard procedure in statistics to find the expectation values of any functions once the (pdf) is obtained. The important role of Geometric Solid Angle (GSA) in classical and modern physics and its relationship to the inventor's TRAJECTORY SOLID ANGLE (TSA) can further be compared and described in the following: The Geometric Solid Angle (GSA), a mathematical definition from differential geometry well known to scientists and engineers for years, has been applied to study the theory of scattering of particles that was summarized and provided with detail references by Watson [8]. It has been also appied to study the kinetic theory of ideal gas as shown by Lee et al [9] and the radiative heat transfer by Hottel et al [10]. The six-dimensional phase space, used in kinetic theory of gases and originated by Maxwell and Boltzmann, has become the foundation of statistica and quantum mechanics. The main idea of statistical mechanics is to apply the laws of probability and methods of statistics to study the mechanics of particles and bodies. Thus the problem of studying the probability of a particle striking on a predesignated area or on another particle in various force fields has been the central issue in statistical mechanics. When this is applied to the photon that carries a definite amount of energy, it becomes the subject of quantum mechanics. However, as asserted by Park [11], the establishment of a rigorous footing on statistical quantum mechanics from the point of view of quantum mechanicists seems to be difficult. This explained why, aside from all known approaches for the P.sub.2 targeting problem, alternative means were continuously sought for a firm answer before and even after 1974 when the (TSA) was first invented. As one traces through all the references as cited, one will find that the (GSA) has been used in various topics for fundamental analysis, calculation and comparison with experiments in both classical and modern physics. Since it has been widely used for a long period of time and thus it was and still is considered by many that the (GSA) being used in various topics of classical and modern physics is the solution of the P.sub.2 targeting problem. This can be challenged by the invention of the (TSA) which contains (GSA) as one of its special case of millions. In summary, the advantages of the invention over all other methods in the past to solve the P.sub.2 targeting problem are: 1. The invention of TRAJECTORY SOLID ANGLE provides the most precise definition to solve the problem for the first time in October 1974. Comparing the (TSA) method with all other methods at that time, all other methods became approximate. For examples: the Monte Caro Methods; the Geometric Solid Angle (GSA) method are all conditionally acurate in some given ranges of parameters but not precise in all ranges of the given parameters. 2. The definition of (TSA) is explicitly defined with all parameters implicitly contained within the definition while all the other methods do not. 3. Due to the precise definition of (TSA), it is applicable for macroscopic bodies as well as for microscopic particles of mathematically defined infinitestimal size under the actions of any force and moment fields between and among the bodies and particles. Therefore, the (TSA) provides great imacts to the entire range of physics; from the calculation of the collision cross sections of sub-nucleus particles in high energy physics and to that of galaxies in astronomy. The applicabilities of all other methods are relatively limited. 4. The Geometric Solid Angle (GSA) of any targeted area, being finite or infinitesimally small, is unchanged with respect to the location of the source where the particle is ejected. The (GSA) is not related to the parameters of ejection of the particle at all. It is a pure mathematical quantity. The TRAJECTORY SOLID ANGLE (TSA) is a term containing all the parameters of generating the particle and the targeted area to be hit. Thus the (GSA) of any targeted area is always finite and unchanged while that of (TSA) can be zero. This explains why the (TSA) can be and should be used to solve the P.sub.2 targeting problem for particles and bodies under the action of any force and moment fields and that the (GSA) can not and should not be considered as the correct solution for the P.sub.2 problem. There will be errors comparing the use of (TSA) between the use of (GSA) to solve the same problem. The errors will range from 0% to 100%. 5. Since the collision cross sections of many problems in central force fields (which include: the hydrogen model; Alpha scattering; moon-earth model; Comet Halley scatters around the solar system . . . etc.) have been based on the use of (GSA) for calculation and have been published in text books around the world, the furture assertion the truth of (TSA) will provide a great impact to all those results in the past. 6. The (TSA) concept and its definition not only confirms the well known Heisenberg's principle of uncertainty in physics, but also provides the precise definition and procedures to calculate the uncertainty in term of numbers as precise as we want. 7. The most important concept of (TSA) is that the definition can be applied to discover new laws and new particles by comparison and matchings of the unknown results with the already confirmed and proved results. If there are new laws of physics that describe the particle motions other than those of Newton's classical mechanics and Einstein's narrow and general relativity, the present (TSA) concept is still applicable to obtain the precise P.sub.2 function for the problem. 8. Four examples are selected to illustrate how to obtain the probability distribution functions by means of (TSA): These examples are; Alpha scattering; particle in uniform, isotropic linear motion; particle under assumed constant gravitatonal pull on a plane; particle in a medium where the resistance force is linearly proportional to the velocity of the particle and under a uniform gravitational field. These examples are selected on the basis that they are well known and can be found from the open literatures. They were selected with the intention to show that even with such simple well known examples, the correct probability functions and cumulative distribution functions of these problems have never been obtained before. Whether exact solutions can be obtained from the equations of motion that govern other problems will not be the issue because the equation of motions can always be solved by means of numerical analysis together with computer programming. The key issue is that through the definition of (TSA), the P.sub.2 functions can be precisely defined and obtained. The (TSA) can be applied to solve the most fundamental problems in physics that include all the subjects listed as cited references in this application.
047117559	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Before describing the handling tool of the present invention, it is believed informative, first, to discuss the structure of an ice basket and the use therein of removable cruciforms, in accordance with above-noted related invention, and with which removable cruciforms the handling tool, and the related method of the present invention, are most advantageously employed. FIG. 1 is an elevational view, in cross-section, of an ice basket 10 having a cylindrical, perforated metal sidewall and divided into a series of compartments, delineated by removable cruciforms 14 in accordance with the related invention. The open, upper end 12a of ice basket 10 affords limited access to the interior of the basket 10, the lower end 12b typically being enclosed by a grating or meshlike end closure (not shown) which is contiguous with support structure (not shown) for the basket 10. In a typical installation, the removable cruciforms 14 of the related invention are disposed at axially displaced positions, or elevations, within the basket 10, corresponding to those of original, welded-in-place cruciforms, and thus are disposed at approximately 6 foot intervals, defining a succession of seven compartments 11-1 through 11-7 delineated by the plurality of cruciforms 14 within the basket 10, each containing initially a full charge of ice. As described in further detail hereinafter, each of the cruciforms 14 is releasably engaged on a stiffening ring (not seen in FIG. 1) for retaining same in position at the desired elevation within the ice basket 10. The cruciforms 14 are seen to perform the intended function of supporting the charges of ice within the corresponding compartments, despite the fact that sublimation has resulted in reduced charges of ice existing within the lower compartments. For example, whereas the charges of ice 9-1 and 9-2 substantially fill the corresponding compartments 11-1 and 11-2, in the lowermost compartments 11-6 and 11-7, significantly depleted charges of ice 9-6 and 9-7, respectively, remain. Whereas removal of the charge of ice at the uppermost compartment 11-1 is feasible with conventional tools since accessible through the open upper end 12a, removal of ice from the successively lower compartments is a difficult task. A preferred instrument which enables efficient and effective removal of ice from each of the successive compartments throughout the entire height of the basket 10 is disclosed in the copending application entitled "Ice Remover Auger for Ice Condention Containment", the inventors of which are coinventors herein, the application furthermore being assigned to the common assignee hereof. It thus will be understood that as the ice in each successive, lower compartment is removed, access may be gained to the corresponding removable cruciform 14 of the related invention, and the same may be retracted and withdrawn, compartment by compartment, thereby to gain access to the lowermost compartment 11-7. The ice basket 10 may then be recharged with ice and the cruciforms 14 reinstalled, in compartment by compartment order. The cruciforms 14 of the related invention, however, also accomodate alternative techniques and related equipment for accomplishing these same purposes, as later described herein. It furthermore should be understood that where possible, removable cruciforms 14 in accordance with the related invention may be employed initially in a new installation, and not merely as a replacement for the conventional welded-in-place cruciforms of prior ice baskets, subsequently to their removal. However, where the removable cruciforms are to be employed in existing ice baskets as a replacement for the welded-in-place, conventional cruciforms, the latter must first be removed. Equipment for performing that function is disclosed in the copending application entitled "Ice Basket Cruciform Removal Tool", the inventor of which is a coinventor herein, the application being assigned to the common assignee hereof. The cruciform 14 of the related invention is shown in detail in the perspective, elevational view of FIG. 2 and, as assembled within an ice basket 10, in the plan view of FIG. 3, taken generally along the cross-sectional view line 3--3 in FIG. 1. Further details of the cruciform 14 of the related invention are set forth in the side elevational view of FIG. 4, partly in cross-section and taken generally along the line 4--4 in FIG. 3, but wherein the sidewall 12 of the ice basket has been removed for simplicity and clarity of illustration. Additionally, the elevational view of FIG. 5 comprising a partial cross-section, taken along line 5--5 in FIG. 3, illustrates details of the internal construction of the cruciform 14. With concurrent reference to FIGS. 2, 3 and 4, the removable cruciform 14 in accordance with the related invention comprises a pair of brackets 16, each of a generally V-shaped, truncated base configuration. Each bracket 16 comprises a central, base portion 17 having parallel longitudinal edges 17-1 and 17-2 from which corresponding integral legs 18 extend at a predetermined angle, so as to assume generally radial orientations relative to the sidewall 12 of an ice basket 10 in which the cruciform 14 is installed, as best seen in FIG. 3. Each of the legs 18 carries a pair of integral, upper and lower feet 19 which extend radially beyond the outer longitudinal edge of the corresponding leg 18 and define a receiving channel 20 therebetween. A pair of support plate assemblies 22 and 24, respectively comprising parallel, soaced plates 22a, 22b, and 24a, 24b, defining corresponding slide channels 23 and 25 therebetween, are secured to and extend in parallel relationship from one of the brackets 16, at right angles to the central portion 17 thereof. As best seen in FIG. 4, a pair of parallel, horizontal slots 26 and 28 are formed so as to extend, in alignment, through each of the parallel support plates 22a, 22b and 24a, 24b. On the other of the brackets 16 there are secured a pair of slide support plates 32 and 34, affixed thereto so as to extend at right angles from the central portion 17 in parallel relationship, and spaced apart so as to be received in telescoping, sliding relationship in the corresponding slide channels 23 and 25 of the support plate assemblies 22 and 24. Each of the slide suoport plates 32 and 34 has secured thereto corresponding pin pairs 36 and 38 at positions aligned with, and for being received through, the respective slots 26 and 28 in the mating support plate assemblies 22 and 24, to restrict, or limit, the telescoping, sliding relationship to a direction parallel to the slots 26 and 28, and a length of travel as defined by the abutment of the pin pairs 36 and 38 with the corresponding, opposite ends of the slots 26 and 28. As can be best appreciated from FIG. 3, the pair of brackets 16 accordingly may be compressed and/or expanded within a limited length of travel along a diameter of the ice basket 10 passing perpendicularly through the respective central portions 17 thereof, and corresponding to a symmetrically disposed, compression/expansion axis of the cruciform 14. As best seen in FIG. 4 the slide support plates 32 and 34 are slighty shorter in axial height (i.e., along the vertical axis of the cruciform 14, corresponding to the vertical axis of the cylindrical basket 10) than the corresponding support plates 22a, 22b and 24a, 24b. For example, support plates 22a, 22b and 24a, 24b, may each be approximately 4 inches in axial height whereas the slide support plates 32 and 34 may be of approximately 3.62 inches in axial height. The V-shaped brackets 16 as well may be of approximately 4 inches in axial height. The central portions 17 of the respective brackets 16 and the telescopingly engaged support plate assemblies and slide support plates 22, 32, and 24, 34, define therewithin a spring housing 40 which is of nominally square cross-section but, as described, may be compressed or expanded within a limited extent of travel along an axis perpendicular to the parallel, central portions 17. A C-shaped spring 42 is received in the housing 40. With concurrent reference to FIGS. 3 to 7, the spring 42 defines a longitudinal, or axially extending opening 43 between its free ends 42a and 42b; while illustrated in FIG. 7 as of circular cross-sectional configuration, corresponding to its installed condition in FIG. 3, the spring 42 in a free configuration (i.e., when not disposed within the housing 40) assumes a normal, expanded configuration. Accordingly, the spring 42 engages the base portions of the brackets 16 and applies a resilient biasing force thereto for maintaining the spaced relationship thereof and the nominally square cross-sectional configuration of the housing 40, the pins 36 and 38 abutting the ends of the slots 26 and 28. Pairs of notches 44 and 46 are formed in the spring 42 at its opposite ends, each pair preferably being symmetrically disposed about a diameter which, as seen in FIG. 7, extends transversely to a diameter passing symmetrically through the opening 43. Pairs of tabs 48 and 50, as seen in FIGS. 3 and 5, are formed on the upper and lower edges of the central portions 17 of both brackets 16 and extend laterally and thus radially inwardly, so as to be received in the corresponding, aligned notches 44 and 46 of the spring 42. The cylindrical sidewall 12 of the ice basket 10 has rigidly secured therein, at spaced elevations, a plurality of stiffening rings 11. A single such stiffening ring 11 is illustrated in FIGS. 3 and 4, which may be welded in place and/or secured to the sidewall 12 by screws 13. In use of the replaceable cruciform 14 of the related invention, the brackets 16 are moved together by compressing the spring 42, as before described, thus effectively retracting the radially extending legs 18. In a specific embodiment of the cruciform, the retraction or compression reduces the effective diameter of the circumferential periphery of the legs and associated feet extensions from 11.90' (as installed and engaged within the basket 10) to 11.50'. This permits lowering the cruciform 14, in a horizontal orientation, axially downwardly through the ice basket 10 to a desired elevation in alignment with a stiffening ring 11. The cruciform 14 then is released from compression while supported at the desired elevation, the C-spring 42 causing the cruciform 14 to expand, advancing the legs 18 toward the sidewall 12 of the ice basket 10 so as to receive the stiffening ring 11 in the channels 20 intermediate the feet 19 of each leg 18. The removable cruciform 14 of the related invention thus satisfies the requirement of being readily manipulated, both for installation into and removal from required elevations within an ice basket, for the purposes hereinbefore set forth. The configuration of the cruciform 14, moreover, is particularly advantageous, taking into account the maintenance functions required to be performed with respect to ice baskets of the type herein considered. Particularly, the cruciform 14 affords equivalent ice charge support functions, as those of the fixed, or welded-in-place, cruciforms of the prior art and, in fact, improves the supoort function in view of the generally square configuration of the spring housing 40, as compared to the relatively more simple, X-shaped configuration of the metal straps of the prior art cruciforms. Significantly, moreover, the mating configuration of the C-shape spring 42, as disposed within the housing 40, affords a central, axially aligned passage throughout the height of a given ice basket 10. Specifically, the spring 42, of approximately 3 inches in diameter for the embodiment as illustrated, when used with an ice basket of approximately one (1) foot diameter, affords a convenient central passageway or column, passing through the geometric center of the ice basket 10 throughout its height, to permit thermal drilling operations to provide an axially extending central hole throughout the height of the ice basket through which maintenance tools may be inserted to remove and settle ice. When in use with such apparatus, the subject cruciforms may be retained in position while ice settling operations are performed. The handling tool of the present invention and the associated method of operation thereof in conjunction with the selective installation and removal of cruciforms of the related invention as hereinabove described, will now be discussed with reference to FIGS. 8 throuoh 12, in which FIGS. 8 and 9 comprise front and side elevational views, respectively, of the tool, each thereof being partially in cross-section and partially broken away for ease and clarity of illustration. FIG. 10 is a top plan view of the tool, taken along line 10--10 in FIG. 8. FIG. 11 is a plan view, taken along line 11--11 in FIG. 9, of a guide assembly and movable guide fingers. FIG. 12 is an air system schematic illustrating associated valves and air cylinders incorporated in the handling tool, for explaining the operation thereof. With concurrent reference to FIGS. 8 through 10, the handling tool 100 comprises, as major components, a clamping assembly 102, best seen in FIG. 8, and a guide assembly 104, best seen in FIG. 9, portions of the guide assembly 104 being removed from the view of FIG. 8 for clarity and ease of illustration. A frame 106 of elongated generally rectangular configuration but including a transversely enlarged central portion 107, comprises the main support element for the tool 100. Eyebolts 108 and 109 are connected thereto at its opposite extremities for receiving a sling 110 by which the tool 100 is supported from a suitable derrick or other device, so as to be lowered into an ice basket 10 from the open, upper end 12a thereof (see FIG. 1). A pair of support plates 112 and 113 of generally an inverted "Y"-shaped outer peripheral configuration are secured at the narrow, upper ends thereof to the frame 106 and extend vertically downwardly therefrom in parallel, spaced relationship. A mounting bar 114 of generally rectangular configuration is configured to receive the lower ends 112b and 113b of the support plates 112 and 113 and is secured thereto by bolts 115 (see FIG. 8). An air cylinder 116 is mounted to the frame 106 by a threaded shaft 117 at the lower end thereof which is received in a corresponding threaded bore 118 centrally disposed in the transversely enlarged central portion 107 of the frame 106. The piston rod, or shaft, 120 of the air cylinder 116 extends downwardly, in generally parallel relationship with the support plates 112 and 113, and carries a clevis 122 at its lower end. A pair of L-shaped arms 124 and 126 are pivotally mounted at their respective corner portions 124a and 126a to the support plates 112 and 113 by corresponding pivot pins 125 and 127 (FIG. 8). As illustrated in partial cross-section in the view of FIG. 9, suitable spacers 128 and 129 are received on the pivot pin 127 to maintain the lever arm 126 properly spaced between support plates 112 and 113, the pivot pin 127 being received through suitable apertures 130 and 131 in the corresponding, lower corner extremities of the parallel supoort plates 112 and 113. It will be understood that arm 124 is similarly supported on the pivot pin 125 at the opposite, lower corner extremities of the support plates 112 and 113. The upper arm portions 124b and 126b of the lever arms 124 and 126 have elongated slots 132 and 134 through which is received a common drive pin 135 (FIG. 8), the opposite ends of which are received through corresponding apertures provided therefor in the parallel, depending legs 122a and 122b of the clevis 122 and suitably secured thereto. Spacers 136 on the drive pin 135 maintain the parallel alignment of the lever arms 124 and 126 (see FIG. 9). A pair of clamping shoes 138 and 140 are pivotally mounting to the lower portions 124c and 126c of the lever arms 124 and 126. The pivotal mounting is afforded by transversely extending, parallel angle bracket pairs 139 and 141 extending transversely from the rear, or outer surfaces of the respective shoes 138 and 140 and corresponding pivot pins 142 and 143 which are received through suitable, aligned apertures in the respective bracket pairs 139 and 141 and in the corresponding, lower portions 124c and 126c of the arms 124 and 126, respectively. The clamping shoes 138 and 140 are shown in solid line in FIG. 8 in the disengaged, or released state as produced by the complementary pivotal movement of the corresponding lever arms 124 and 126 to the rest, or solid line positions shown in FIG. 8, producing relative, outward displacement of the corresponding lower lever arms 124c and 126c. The pivotal actuation of the lever arms 124 and 126 is produced by selective energization of the air cylinder 116 for driving the corresponding piston rod 120 thereof to the extended, axially downward position, at which position the common drive pin 135 is shown in solid lines (in cross-section) in FIG. 8. Conversely, by selective actuation of air cylinder 116 to withdraw or retract the piston rod 120 and thus move same in a vertically upward direction so as to translate the common drive pin 135 from the solid line to the dotted line position indicated in FIG. 8, the lever arms 124 and 126 are pivoted in complementary, opposite directions so as to rotate the respective upper arm portions 124b and 126b in an upward direction (as illustrated in dotted line for the upper arm portion 124b of the lever arm 124 in FIG. 8) and correspondingly to inwardly displace the lower lever arm portions 124c, 126c and thereby to move the corresponding lamping shoes 138, 140 into an engaged, or clamping state (as shown by dotted lines in FIG. 8 for the lower arm portion 124c and the clamping shoe 138). As explained in more detail hereafter, the selective, engaging or clamping state, and the disengaged or releasing state of the shoes 138 and 140 are employed in conjunction with a removable cruciform 14 as before described. Particularly, the spring housing 40 of such a cruciform is shown in cross-section in FIG. 8 at a rest or fully expanded condition, disposed between the shoes 138 and 140 in their disengaged or released state, all as illustrated in solid lines in FIG. 8. Actuation of the shoes 138 and 140 to the engaged or clamping state causes the shoes 138 and 140 to engage the base portions 17 of the corresponding brackets 16 of the cruciform 14 and move same together to the dotted line positions indicated in FIG. 8, compressing the spring (not shown in FIG. 8) within the housing 40. The guide assembly 104 comprises a pair of guide fingers 150 which, as seen from FIG. 11, have an outer, arcuate periphery and, as best seen in FIG. 9, an undercut segment 152 and an inwardly tapered surface 153 which function together to facilitate centering of the guide fingers 150 relative to a stiffening ring 11 and engaging same thereby, as shown in FIGS. 3 and 4. Inasmuch as each of the supporting and actuating structures for both guide fingers 150 are the same, reference will be had concurrently to both thereof; with reference to FIG. 9, the supporting structure for the left-hand guide finger 150 is shown in cross-section whereas the supporting structure for the right-hand guide finger 150 is shown only partially in cross-section and remaining portions in phantom lines, to facilitate the following description thereof. Each guide finger 150 includes an integral shank 155 which is received in an elongated recess 157 in the upper surface of the mounting bar 114 and secured therein for telescoping, reciprocal sliding movement by a pair of plates 158 and 159 which are bolted by bolts 160 to the mounting bar 114. As better seen for the left-hand guide finger 150 in FIG. 9, an open, elongated slot 162 is formed in the central portion of, and in alignment with, the recess 157 in the mounting bar 114. A corresponding, open elongated slot 164 is formed in the integral shank 155 of the guide finger 150 in aligned relationship with slot 162. A lever arm 166 comprises an upper, horizontal arm segment 167 and an angularly, downwardly depending arm segment 168 which is received throuoh the longitudinally aligned slots 162 and 164. The aim segment 168 further includes a correspondingly, angularly oriented, elongated slot 169 within which is receiving a ballbearing 170, the latter housing a pin 172 which is engaged at its opposite ends (see FIG. 11) in the parallel sidewall portions 155a bounding the open elongated slot 164 in the shank 155, at generally centrally disposed positions relative to the elongated dimension of the slot 164. Each lever arm 166 is secured at its upper horizontal arm seoment to a piston rod 174 of an air cylinder 176, the latter secured by a suitable mounting blocks 178 and bolts 180 to the respectively corresponding support plates 112 and 113. As is believed apparent, suitable, selective actuation of the pair of air cylinders 176 will selectively drive the lever arms 166 in corresponding, vertically reciprocating opposite directions and, due to the angular inclination of the legs 168, cause the guide fingers 150 to move in complementary outward, or inward directions. As shown by the phantom line representation of the lower portion of the arm segment 168 of the left-hand guide finger 150 in FIG. 9, the aligned slots 162 and 164 permit the downward movement therethrough of the angularly depending arm segment 168, so as to withdraw, or retract, the corresponding drive finger 150 to the dotted, or phantom line position indicated. The air cylinders 116 and 176, and the associated actuating or driving means therefor, are conventional and thus the same are illustrated in simplified fashion in FIGS. 9 and 10. Very briefly, a pair of brackets 182 and 184 are secured, as illustrated by bolts 183 and 185, to the frame 106. A first solenoid operated valve 186 having dual outputs is connected on the bracket 182 for operating the pair of air cylinders 176 associated with the clamping assembly 102. As indicated, in part schematically, conduits or pressure hoses 188 connect the dual outputs of the valve 186 to the corresponding inputs of the dual air cylinders 176 to produce a downward stroke of the corresponding piston rods 174 thereof, and, as similarly indicated, a pair of pressure hoses 190 is connected to the respective pair of air cylinders 176 for effecting the reverse actuation of the air cylinder 176, to withdraw or retract the piston rods 174 thereof. A further solenoid operated valve 192 mounted on bracket 184 includes corresponding conduits 193 and 195 for similarly actuating air cylinder 116, to extend or retract the associated piston rod 120. Connector blocks 194 and 196 provide for connections between the solenoid operated valves 186 and 192 and electrical wiring assemblies 197 and 198 and a major air pressure conduit 199, for driving the respectively associated air cylinders. For convenience, the major air pressure supply conduit 199 and the wiring assemblies 197 and 198 are secured by a cable tie 200 and linked to the cable or other structure by which the tool 100 is supported through sling 110, to facilitate their being lowered in common with the tool 100 into an ice basket. FIG. 12 is a simplified air system schematic, indicating the relationship of the major air pressure conduit 199 and its connection to the above-mentioned solenoid operated valves 186 and 192, and the connections of the latter to the respectively associated air cylinder 116 of the clamping assembly 102 and the pair of air cylinders 176 of the guide assembly 104. As is apparent, selective, opposite actuation of the respective valves 186 and 192 produces correspondingly, selective, opposite actuation of the air cylinders 116 and 176. In operation, the tool 100 of the invention is first connected to suitable supplies of electrical power (e.g., 100 volts) and an air pressure supply (e.g., 90 psi). Toggle switches (not shown) are provided, accessible at all times from the exterior of an ice basket into which the tool 100 is lowered, for selectively energizing solenoid valves 186 and 192 and thereby actuating the associated air cylinders 116 and 176 of the clamping and guide assemblies 102 and 104. Particularly, for inserting a cruciform 14, the guide assembly 104 is actuated for withdrawing or retracting the guide fingers 150 so as to permit lowering tool 100 axially downwardly through the ice basket 10. A removable cruciform 14 is positioned to dispose the spring housing 40, and particularly the base portions 17 of the brackets 16, between the shoes 138 and 140. The clamping assembly 102 then is actuated so as to move the shoes 138 and 140 in a compressing or engaging direction, thereby compressing the C-spring 42 and causing the base portions 17 of the bracket 16 to move together to the dotted line positions illustrated in FIG. 8. The tool 100, thus holding a removable cruciform 14 in engaged condition, is lowered to the desired elevation within the ice basket 10 to a position slightly above (e.g., approximately 6 inches) the stiffening ring 11 with respect to which the cruciform 14 is to be installed. The guide assembly 104 then is actuated to extend the guide fingers 150 outwardly and the tool 100 then is further lowered until the guide fingers 150 rest on the ring 11, receiving same in the notch 152. The clamping assembly 102 then is operated to release, or disengage, the shoes 138 and 140 and permit the housing 40 to expand under the resilient force of the C-spring 42 so as to project the legs 18 outwardly and engage the ring 11 within the corresponding channels 20. After proper orientation and engagement of the cruciform 14 onto the ring 11 is verified, the guide assembly 104 is actuated to retract the guide fingers 150 and thereby permit removal of the tool 100 from within the ice basket 10. The operating procedure for removing a removable cruciform already installed in an ice basket 10 is as follows. First, the guide fingers 150 are retracted and the shoes 138 and 140 are actuated to the disengaged position. The tool 100 then is lowered within the basket 10 so as to be disposed in a position substantially as shown in FIG. 8, with mounting bar 131 resting on the upoer edges of the walls of the housing 40, and with the shoes 138 and 140 disposed adjacent the parallel base portions 17 of the housing 40. The clamping assembly 102 then is actuated to engage the shoes 138 and 140 with, and correspondingly compress, the housing 40 thereby retracting the legs 18 and releasing the cruciform from the stiffening ring 11, whereupon the tool 100 with the engaged cruciform 14 is removed from the ice basket. The clamping assembly 102 then is actuated to disengage the shoes 138, 140 from the housing 40 of the removed cruciform 14. In accordance with the foregoing, it will be seen that the handling tool of the present invention affords effective and efficient handling of removable cruciforms having a central compressible spring-loaded portion whereby the same may be compressed, to assume a reduced outer dimensional configuration either for removal from an ice basket, or for travel through the ice basket to a desired retaining ring elevation, and then remotely released to expand, by virtue of internal spring-loading, and automatically engage the retaining ring and be locked in position therewith. It thus will be understood that the handling tool and method of the present invention are not restricted to the specific cruciform configuration of the related invention, but are highly advantageous when used therewith. Accordingly, numerous modifications and adaptations of the handling tool of the invention will be apparent to those of skill in the art and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the true spirit and scope of the invention.
	abstract	An optical collector (15) for collecting extreme ultraviolet radiation or EUV light generated at a central EUV production site comprises a reflective shell (25). To cope with thermal loading of the collector and avoid deformations, the reflective shell (25) is mounted on a support structure (24), such that a cooling channel (29) is established between the back side of the reflective shell (25) and the support structure (24), the thickness of the reflective shell (25) is substantially reduced, such that the convective heat transfer between the back side of the reflective shell (25) and a cooling medium (26) flowing through the cooling channel (29) dominates the process of removing heat from the reflective shell (25) with respect to heat conduction, and a cooling circuit (33) is connected to the cooling channel (29); to supply a cooling medium (26) to the cooling channel (29) with a controlled coolant pressure and/or mass flow.
	description	The present application claims priority under 35 U.S.C. 119 to Korean Patent Application No. 10-2011-0067724, filed on Jul. 8, 2011, the disclosure of which is expressly incorporated by reference herein in its entirety. 1. Field of the Invention The present invention relates, in general, to an apparatus for measuring dimensions of a spacer grid for nuclear fuel assemblies and, more particularly, to an apparatus for measuring dimensions of a spacer grid for nuclear fuel assemblies, capable of measuring all the sides of the spacer grid that support the nuclear fuel assemblies to accurately detect abnormalities in the spacer grid, preventing the spacer grids from interfering with each other, and preventing malfunctions from occurring in the real situation of a nuclear reactor in advance to provide reliability. 2. Description of the Related Art Atomic power generation based on a light water reactor is designed to generate energy via the fission of nuclear fuel and use the energy to heat primary cooling water, transmit the energy of the heated primary cooling water to secondary cooling water in a steam generator to generate steam, convert the generated steam into rotational energy with a steam turbine, and produce electricity with a generator. In general, apparatuses that measure spacer grids for the light water reactor measure all the sides of a spacer grid for a plurality of nuclear fuel assemblies stored at a fuel storage place. All the sides of the spacer grid are measured using such a spacer grid measuring apparatus, thereby detecting abnormalities in the sides of the spacer grid. Examples of the related art include Korean Patent No. 10-0784008, entitled “NUCLEAR FUEL ASSEMBLY LOW PRESSURE DROP TOP NOZZLE” and Korean Patent Application Publication No. 10-2001-0029780, entitled “FUEL ASSEMBLY MECHANICAL FLOW RESTRICTION APPARATUS FOR DETECTING FAILURE IN SITU OF NUCLEAR FUEL RODS IN A FUEL ASSEMBLY DURING REACTOR SHUTDOWN.” As shown in FIG. 1, an apparatus for measuring a spacer grid of the related art includes a fixing unit 10 fixed to a measuring table 30 placed on a floor and kept safe from vibrations caused by external force. A pair of measuring units 20 is mounted on the fixing unit 10. The pair of measuring units 20 is capable of grasping both sides of a rectangular spacer grid 40 disposed therein and moving in forward and backward directions, thereby measuring the both sides of the spacer grid 40. However, the measuring units are too short to measure the whole length of the sides of the spacer grid, so that there can be unmeasured portions. Thus, abnormalities in the unmeasured portions of the spacer grid cause abnormal effects in the supported nuclear fuel assemblies when operated. Accordingly, the present invention has been made keeping in mind the above problems of the related art, and an objective of the present invention is to provide an apparatus for measuring dimensions of a spacer grid for nuclear fuel assemblies, capable of measuring all the sides of the spacer grid for the nuclear fuel assemblies to accurately detect abnormalities in the measured spacer grid, avoiding reducing the life span of the nuclear fuel assemblies, and preventing malfunctions from occurring in the real operation of a nuclear reactor to provide reliability. In order to achieve the above described objective, according to one aspect of the present invention, there is provided an apparatus for measuring the dimensions of a spacer grid for nuclear fuel assemblies stored at a fuel storage place for use in a light water reactor. The apparatus comprises: a fixing unit fixed to a measuring table placed on a floor and kept safe from vibrations caused by external force; a measuring unit mounted on the fixing unit and configured so that measuring members are installed in both sides of a rectangular spacer grid in a tong-like shape so as to grasp the sides of the spacer grid, in which a plurality of nuclear fuel assemblies are retained, move in forward and backward directions by cylinders, and measure abnormalities of the sides of the spacer grid; and a displacement measuring unit mounted on one side of the measuring unit and sending the measured abnormalities of the sides of the spacer grid to the outside. Here, the fixing unit can include: a main fixing member that has a “C” shape and includes through-holes of a predetermined diameter in upper and lower plates thereof; a base member that has a rectangular shape and includes middle protrusion pieces horizontally mounted on and fastened to the main fixing member and finish pieces formed at both ends thereof; and an auxiliary fixing member that includes a connection piece configured to be interposed between the pair of upper and lower protrusion pieces that are formed in the middle of the base member, and support pieces formed on both sides of the connection piece in mirror symmetry. Further, the measuring unit can include: a pair of movable members, each of which is horizontally coupled to first rails via a short shaft piece between the auxiliary fixing member coupled to the protrusion pieces of the base member and the finish pieces so as to move along the first rails in left and right directions and includes a long shaft piece extending perpendicular to the short shaft piece; and measuring members, each of which is formed in parallel to the long shaft piece of each movable member, moves along a second rail, one end of which is integrally fixed to the short shaft piece, in forward and backward directions, and measures one of the both sides of the grasped spacer grid. Further, the auxiliary fixing member can be assembled in such a manner that a fixing pin is fitted into a series of holes aligned when the connection piece thereof is interposed between the protrusion pieces of the base member and when the protrusion pieces of the base member connection piece are interposed between the upper and lower plates of the main fixing member. Each measuring member can include: an L-shaped connection piece that is fitted around the second rail formed in parallel to the long shaft piece at a lower portion thereof and that moves in the forward and backward directions; a transfer piece that is integrally fixed to a top surface of the lower portion of the connection piece, that is coupled with a transfer pipe, that is partially inserted into a guide channel of the long shaft piece, and that is fitted around the transfer pipe spaced apart from the second rail by a predetermined distance so as to move in the forward and backward directions; and a grip piece that has a contact piece protruding in the middle of one side of the connection piece, the other side of which is in contact with the transfer piece, and that grasps one of the both sides of the spacer grid. Further, the displacement measuring unit can be inserted into and fixed in a mounting piece mounted on one side of the short shaft piece with the base member interposed between the mounting piece and the short shaft piece. In addition, the displacement measuring unit can send measurement information, for example, a variation of length caused by the abnormalities in the sides of the spacer grid which was measured by the movement of the grip pieces, to the outside. Also, the measuring unit can measure the whole length of the sides of the spacer grid when the movable members move along the first rails in the left and right directions and when the measuring members move along the second rails in the forward and backward directions. The grip piece can be formed of synthetic resin so that an outer surface of the spacer grid is not damaged or scratched. Further, the first cylinder can supply air or oil pressure to the transfer pipe so that the measuring member moves toward the short shaft piece, and the second can supply air or oil pressure to the transfer pipe so that the measuring member moves away from the short shaft piece. According to the present invention as described above, the whole length of the sides of the spacer grid for the nuclear fuel assemblies can be measured by adjusting the distance moved, so that any abnormality in the measured spacer grid can be accurately detected. Further, it is possible to prevent the life span of the nuclear fuel assembly from being reduced, and to prevent malfunctions from occurring in the real situation of a nuclear reactor in advance to provide excellent reliability. Reference will now be made in greater detail to an exemplary embodiment of the invention with reference to the accompanying drawings. The structure of an apparatus for measuring dimensions of a spacer grid of a nuclear fuel assembly according to an exemplary embodiment of the present invention will be described below with reference to FIGS. 2 to 6B. FIG. 2 is a perspective view showing an apparatus for measuring dimensions of a spacer grid of a nuclear fuel assembly according to an exemplary embodiment of the present invention. FIG. 3 is a perspective view showing a fixing unit, a measuring unit, and a displacement measuring unit that are assembled in accordance with the exemplary embodiment of the present invention, whereas FIG. 4 is a perspective view showing the fixing unit, the measuring unit, and the displacement measuring unit that are disassembled in accordance with the exemplary embodiment of the present invention. FIG. 5 is a perspective view showing the displacement measuring unit mounted on the measuring unit in accordance with the exemplary embodiment of the present invention. FIGS. 6A and 6B are perspective views showing a measuring member moving in forward and backward directions in accordance with the exemplary embodiment of the present invention. As shown in FIGS. 2 to 4, the apparatus for measuring dimensions of a spacer grid of a nuclear fuel assembly according to an exemplary embodiment of the present invention includes a fixing unit 100, a measuring unit 200, and a displacement measuring unit 300. The fixing unit 100 is fixed to a measuring table 400, and is kept in a secured state by the measuring table from vibrations caused by external force. The measuring table 400 is mounted on a XYZ test table (not shown) which is driven by a plurality of cylinders. The fixing unit 100 includes a main fixing member 110, a base member 120, and an auxiliary fixing member 130. The main fixing member 110 has a “C” shape, and includes through-holes 111 of a predetermined diameter which pass through upper and lower plates thereof. The base member 120 has a rectangular shape and is mounted on and fixed to the main fixing member 110. Also, the base member 120 includes middle protrusion pieces 121 to fasten the base member 120 to the main fixing member 110 and finish pieces 123 formed at both ends thereof. The base member 120 is designed so that fastening holes 122 of the middle protrusion pieces 121 are aligned with the through-holes 111 of the main fixing member 110 and thereto a fixing pin P is inserted to couple the main fixing member 110 and the base member 120. The protrusion pieces 121 having a polygonal shape are formed on the inner surface of the base member 120, and are spaced apart from each other by a predetermined distance The finish pieces 123 of the base member 120 are each provided with an insertion hole 124 having a predetermined diameter. Two pairs of first rails R1, each of which has a predetermined length, are inserted into the insertion holes 124, respectively. The first rails R1 pass through the insertion holes 124 of the finish pieces 123, and then are mounted into the auxiliary fixing member 130 interposed between the protrusion pieces 121 of the base member 120. The auxiliary fixing member 130 includes a connection piece 131 configured to be interposed between the pair of upper and lower protrusion pieces 121 that are formed in the middle of the base member 120, and support pieces 132 formed on both sides of the connection piece 131 in a mirror symmetry. The support pieces 132 of the auxiliary fixing member 130, which are symmetrical between the left and right sides, are each provided with a pair of mounting holes 133 so that the first rails R1 can be mounted. The auxiliary fixing member 130 is assembled in such a manner that the fixing pin P is forcibly fitted into a series of holes, including the through-holes 111 and the fastening holes 122, aligned when the protrusion pieces 121 of the base member 120, between which the connection piece 131 is interposed, are interposed between the upper and lower plates of the main fixing member 110, so that the auxiliary fixing member 130 can be kept securely in an assembled state from external shocks and vibrations. In the embodiment, the main fixing member 110, the base member 120, and the auxiliary fixing member 130 are coupled by the fixing pin P. This configuration, however, is merely one example for achieving the objective of the present invention, and thus the present invention is not limited to this configuration. It is apparent to those skilled in the art that the present invention can provide the same effect even in the case of using screws, rivets, bolts, and so forth. The measuring unit 200 is movably fitted around the first rails R1 mounted between the auxiliary fixing member 130 and the finish pieces 123 of the base member 120. The measuring unit 200 is configured so that measuring members 220 are installed in both sides of a rectangular spacer grid 500 in a tong-like shape so as to grasp the both sides of the spacer grid 500, in which a plurality of nuclear fuel assemblies are held, and move in forward and backward directions by cylinders 230a and 230b, and measure abnormalities in the sides of the spacer grid 500. The measuring unit 200 includes a pair of movable members 210 and a pair of measuring members 220. Each movable member 210 is configured so that a short shaft piece 211 thereof is horizontally coupled to the first rails R1 between the auxiliary fixing member 130 coupled to the protrusion pieces 121 of the base member 120 and the finish pieces 123 of the base member 120 so as to move along the first rails R1 in left and right directions, and includes a long shaft piece 212 extending from the short shaft piece 211 perpendicular to the short shaft piece 211. The short shaft piece 211 includes transfer holes 213 into which the first rails R1 mounted between the finish piece 123 of the base member 120 and the auxiliary fixing member 130, are fitted respectively, and thereby the short shaft piece 211 moves in the left and right directions along the first rails R1. The short shaft piece 211 can be freely moved in the left and right directions by a unit (not shown) mounted on a lower portion thereof, and come into close contact with the spacer grid 500. The measuring members 220 move in the forward and backward directions on second rails R2, each of which is installed in parallel on the long shaft piece 212 of each movable member 210 and is integrally fixed to the short shaft piece 211 at one end thereof. Thereby, the both sides of the spacer grid 500 are measured. Each measuring member 220 includes a connection piece 221, a transfer piece 222, and a grip piece 223. The connection piece 221 is formed in an L shape of which a lower portion is fitted around the second rail R2 that is installed in parallel to the long shaft piece 212 so as to move in the forward and backward directions. The transfer piece 222 is integrally fixed to a top surface of the lower portion of the connection piece 221, is coupled with a transfer pipe 224, and is partially inserted into a guide channel 215 of the long shaft piece 212. The transfer piece 222 is fitted around the transfer pipe 224 spaced apart from the second rail R2 in a predetermined distance so as to move in the forward and backward directions. The measuring unit 200 measures the both sides of the spacer grid 500 when the movable members 210 move along the first rails R1 in the left and right directions and when the measuring members 220 move along the second rails R2 in the forward and backward directions. A contact piece 225 protrudes in the middle of one side of the connection piece 221, the other side of which is in contact with the transfer piece 222, thereby causing the grip piece 223 to grasp one of the both sides of the spacer grid 500. The contact piece 225 protrudes toward the spacer grid 500 in a streamlined shape, and comes into close contact with the grasped spacer grid 500. The grip piece 223 is formed of synthetic resin so that an outer surface of the spacer grid 500 is not damaged or scratched. In this embodiment, the material of the grip piece 222 is synthetic resin, but the present invention is not limited to this material. The displacement measuring unit 300 is mounted on one side of the measuring units 200, and sends the measured abnormalities in the both sides of the spacer grid 500 to the outside. The displacement measuring unit 300 is inserted into and fixed to a mounting piece 310 mounted on one side of the short shaft piece 211 with the base member 120 interposed between the short shaft piece 211 and the mounting piece 310. The displacement measuring unit 300 sends measurement information to the outside. The measurement information includes a variation in length caused by abnormalities in the sides of the spacer grid 500, which is measured by the movement of the grip pieces 223. The displacement measuring unit 300 employs an electrical transformer such as a linear variable differential transformer (LVDT) that measures a difference in linear distance. For example, three solenoid coils are located around a tube, among which one is located between the others and is a primary coil. Thus, a magnetic core moves along the center of the tube, and informs about the position of a measurement target. As shown in FIG. 5, the mounting piece 310 in which the displacement measuring unit 300 is inserted and fixed, is inserted into a rectangular slot formed in the base member 120. The displacement measuring unit 300 is mounted on one side of the short shaft piece 211 of the movable member 210 that is in close contact with an inner side of the base member, and moves in the left and right directions to come into close contact with the both sides of the spacer grid 500. The displacement measuring unit 300 sends the measurement information about the abnormalities in the sides of the spacer grid 500 to the outside using a cable. As shown in FIGS. 6A and 6B, the measuring member 220 freely moves in the forward and backward directions using a pair of cylinders 230a and 230b connected to nozzles 214 provided on both ends of the transfer pipe 224. The pair of cylinders 230a and 230b is configured so that the first cylinder 230a is connected to one end of the transfer pipe 224 and the second cylinder 230b is connected to the other end of the transfer pipe 224. When the first cylinder 230a supplies the transfer pipe 224 with air or oil pressure, the measuring member 220 moves toward the short shaft piece 211. In contrast, when the second cylinder 230b supplies the transfer pipe 224 with air or oil pressure, the measuring member 220 moves away from the short shaft piece 211. Use and operation of the apparatus for measuring dimensions of a spacer grid of a nuclear fuel assembly having the aforementioned configuration according to the exemplary embodiment of the present invention will be described below. First, as shown in FIGS. 2 to 4, the apparatus for measuring dimensions of a spacer grid of a nuclear fuel assembly is previously assembled and modularized at a workshop. The measuring unit 200 has enough size to measure various spacer grids 500 for a plurality of nuclear fuel assemblies. As shown in FIG. 5, the displacement measuring unit 300 is inserted into and fixed in the mounting piece 310 mounted on one side of the short shaft piece 211 that is a component of the measuring unit 200. The displacement measuring unit 300 sends measurement information about the abnormalities in the spacer grid 500 which is measured by the measuring unit 200 to the outside. As shown FIGS. 6A and 6B, the movable member 210 moves in the left and right directions using a separate unit mounted on a lower portion of the short shaft piece 211, and comes into close contact with the spacer grid 500. Then, the first cylinder 230a connected to one end of the transfer pipe 224 supplies air or oil pressure, and thus the measuring member 220 moves forward to minutely measure the both sides of the closely contacted spacer grid 500, so that it is possible to detect the abnormalities in the both sides of the spacer grid 500. In contrast, the second cylinder 230b connected to the other end of the transfer pipe 224 supplies air or oil pressure, and thus the measuring member 220 moves forward to measure in minute detail the both sides of the spacer grid 500, so that it is possible to detect the abnormalities in the both sides of the spacer grid 500. Further, when any overlooked or suspicious point is found in the process of measuring the spacer grid 500, the movement of the measuring member 220 is adjusted using the first and second cylinders 230a and 230b, so that it is possible to more accurately detect the abnormalities in the both sides of the spacer grid 500. When the other unmeasured sides of the spacer grid 500 are measured by the measuring member 220, the spacer grid 500 is rotated and then is measured in the aforementioned sequence. Thus, the measuring unit 200 freely moves in the left and right directions and in the forward and backward directions to measure all the sides of the spacer grid 500, so that it is possible to accurately detect the abnormalities in the both sides of the spacer grid 500, and to store and use the nuclear fuel assembly for a long time. Although the exemplary embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
062529382	abstract	A grid, for use with electromagnetic energy emitting devices, includes at least metal layer, which is formed by electroplating. The metal layer includes top and bottom surfaces, and a plurality of solid integrated walls. Each of the solid integrated walls extends from the top to bottom surface and having a plurality of side surfaces. The side surfaces of the solid integrated walls are arranged to define a plurality of openings extending entirely through the layer. All of the walls can extend at 90.degree. with respect to the top and bottom surfaces, or alternatively, some of the walls can extend at an angle other than 90.degree. with respect to the top and bottom surfaces, such that the directions in which the walls extend all converge at a point in space at a predetermined distance from the front surface of the at least one layer. At least some of the walls also can include projections extending into the respective openings formed by the walls.
042591520	abstract	Method and apparatus for detecting failure in a welded connection, particrly applicable to not readily accessible welds such as those joining components within the reactor vessel of a nuclear reactor system. A preselected tag gas is sealed within a chamber which extends through selected portions of the base metal and weld deposit. In the event of a failure, such as development of a crack extending from the chamber to an outer surface, the tag gas is released. The environment about the welded area is directed to an analyzer which, in the event of presence of the tag gas, evidences the failure. A trigger gas can be included with the tag gas to actuate the analyzer.
	description	1. Field Example embodiments relate to inspection, maintenance, and repair apparatuses and methods for nuclear reactors. Additionally, example embodiments relate to inspection, maintenance, and repair apparatuses and methods for nuclear reactors in confined areas, such as within the downcomer annulus between the reactor pressure vessel and the core shroud. 2. Description of Related Art FIG. 1 is a sectional view, with parts cut away, of a typical reactor pressure vessel (“RPV”) 100 in a related art nuclear boiling water reactor (“BWR”). During operation of the BWR, coolant water circulating inside RPV 100 is heated by nuclear fission produced in core 102. Feedwater is admitted into RPV 100 via feedwater inlet 104 and feedwater sparger 106 (a ring-shaped pipe that includes apertures for circumferentially distributing the feedwater inside RPV 100). The feedwater from feedwater sparger 106 flows downwardly through downcomer annulus 108 (an annular region between RPV 100 and core shroud 110). Core shroud 110 is a stainless steel cylinder that surrounds core 102. Core 102 includes a multiplicity of fuel bundle assemblies 112 (two 2×2 arrays, for example, are shown in FIG. 1). Each array of fuel bundle assemblies 112 is supported at its top by top guide 114 and at its bottom by core plate 116. Top guide 114 provides lateral support for the top of fuel bundle assemblies 112 and maintains correct fuel-channel spacing to permit control rod insertion. The coolant water flows downward through downcomer annulus 108 and into core lower plenum 118. The coolant water in core lower plenum 118 in turn flows upward through core 102. The coolant water enters fuel bundle assemblies 112, wherein a boiling boundary layer is established. A mixture of water and steam exits core 102 and enters core upper plenum 120 under shroud head 122. Core upper plenum 120 provides standoff between the steam-water mixture exiting core 102 and entering standpipes 124. Standpipes 124 are disposed atop shroud head 122 and in fluid communication with core upper plenum 120. The steam-water mixture flows through standpipes 124 and enters steam separators 126 (which may be, for example, of the axial-flow, centrifugal type). Steam separators 126 substantially separate the steam-water mixture into liquid water and steam. The separated liquid water mixes with feedwater in mixing plenum 128. This mixture then returns to core 102 via downcomer annulus 108. The separated steam passes through steam dryers 130 and enters steam dome 132. The dried steam is withdrawn from RPV 100 via steam outlet 134 for use in turbines and other equipment (not shown). The BWR also includes a coolant recirculation system that provides the forced convection flow through core 102 necessary to attain the required power density. A portion of the water is sucked from the lower end of downcomer annulus 108 via recirculation water outlet 136 and forced by a centrifugal recirculation pump (not shown) into a plurality of jet pump assemblies 138 (only one of which is shown) via recirculation water inlets 140. The jet pump assemblies 138 are circumferentially distributed around the core shroud 110 and provide the required reactor core flow. A typical BWR includes 16 to 24 inlet mixers. As shown in FIG. 1, related art jet pump assemblies 138 typically include a pair of inlet mixers 142. Each inlet mixer 142 has an elbow 144 welded thereto which receives pressurized driving water from a recirculation pump (not shown) via inlet riser 146. An exemplary inlet mixer 142 includes a set of five nozzles circumferentially distributed at equal angles about the inlet mixer axis. Each nozzle is tapered radially inwardly at its outlet. The jet pump is energized by these convergent nozzles. Five secondary inlet openings are radially outside of the nozzle exits. Therefore, as jets of water exit the nozzles, water from downcomer annulus 108 is drawn into inlet mixer 142 via the secondary inlet openings, where it is mixed with coolant water from the recirculation pump. The coolant water then flows into diffuser 148. Core shroud 110 may include, for example, a shroud head flange (not shown) for supporting shroud head 122, an upper shroud wall (not shown) having a top end welded to the shroud head flange, a top guide support ring (not shown) welded to the bottom end of the upper shroud wall, a middle shroud wall (not shown) having a top end welded to the top guide support ring and including two or three vertically stacked shell sections (not shown) joined by mid-shroud attachment weld(s), and an annular core plate support ring (not shown) welded to the bottom end of the middle shroud wall and to the top end of a lower shroud wall (not shown). The entire shroud is supported by a shroud support (not shown), which is welded to the bottom of the lower shroud wall, and by an annular jet pump support plate (not shown), which is welded at its inner diameter to the shroud support and at its outer diameter to RPV 100. Typically, the material of core shroud 110 and associated welds is austenitic stainless steel having reduced carbon content. The heat-affected zones of the shroud girth welds, including the mid-shroud attachment weld(s), have residual weld stresses. Therefore, mechanisms are present for mid-shroud attachment weld(s) and other girth welds to be susceptible to intergranular stress corrosion cracking (IGSCC). IGSCC in the heat affected zone of any shroud girth seam weld diminishes the structural integrity of core shroud 110, which vertically and horizontally supports top guide 114 and shroud head 122. In particular, a cracked core shroud 110 increases the risks posed by a loss-of-coolant accident (LOCA) or seismic loads. During a LOCA, the loss of coolant from RPV 100 produces a loss of pressure above shroud head 122 and an increase in pressure inside core shroud 110, i.e., underneath shroud head 122. The result is an increased lifting force on shroud head 122 and on the upper portions of core shroud 110 to which shroud head 122 is bolted. If core shroud 110 has fully cracked girth welds, the lifting forces produced during a LOCA could cause core shroud 110 to separate along the areas of cracking, producing undesirable leaking of reactor coolant. Also, if the weld zones of core shroud 110 fail due to IGSCC, there is a risk of misalignment from seismic loads and damage to core 102 and the control rod components, which would adversely affect control rod insertion and safe shutdown. Thus, core shroud 110 needs to be examined periodically to determine its structural integrity and the need for repair. Ultrasonic inspection is a known technique for detecting cracks in nuclear reactor components. The inspection area of primary interest is the outside surface of core shroud 110 at the horizontal and/or vertical mid-shroud attachment weld(s). However, core shroud 110 is difficult to access. Installation access is limited to the annular space between the outside of core shroud 110 and the inside of RPV 100, between adjacent jet pump assemblies 138. Scanning operation access is additionally restricted within the narrow space between core shroud 110 and jet pump assemblies 138, which is about 0.5 inch wide in some locations. The inspection areas are highly radioactive and may be located under water, 50 feet or more below an operator's work platform. As a result, inspection of core shroud 110 and/or RPV 100, as well as all other inspection, maintenance, and repair within downcomer annulus 108 often is difficult and complicated. Solutions to the problem of inspecting core shroud 110 have been proposed, as discussed, for example, in U.S. Pat. No. 5,586,155 (“the '155 patent”). The disclosure of the '155 patent is incorporated in this application by reference. However, these proposed solutions do not include inspection, maintenance, and repair apparatuses and methods for nuclear reactors similar to the present invention. Example embodiments relate to inspection, maintenance, and repair apparatuses and methods for nuclear reactors. Additionally, example embodiments relate to inspection, maintenance, and repair apparatuses and methods for nuclear reactors in confined areas, such as within the downcomer annulus between the reactor pressure vessel and the core shroud. In an example embodiment, a method of inspecting a nuclear reactor may include: operatively connecting a fixing device, a first track, an arm, and an effector to form an inspection apparatus; inserting the inspection apparatus into the reactor; fixing the inspection apparatus within the reactor; and/or operating the inspection apparatus. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In another example embodiment, a method of performing maintenance on a nuclear reactor may include: operatively connecting a fixing device, a first track, an arm, and one or more tools to form a maintenance apparatus; inserting the maintenance apparatus into the reactor; fixing the maintenance apparatus within the reactor; and/or operating the maintenance apparatus. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In yet another example embodiment, a method of repairing a nuclear reactor may include: operatively connecting a fixing device, a first track, an arm, and one or more sensors, one or more tools, or one or more sensors and one or more tools to form a repair apparatus; inserting the repair apparatus into the reactor; fixing the repair apparatus within the reactor; and/or operating the repair apparatus. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In still another example embodiment, an apparatus for inspecting a nuclear reactor may include: a first track; an arm; a fixing device; and/or an effector. The arm may be operatively connected to the first track. The fixing device may be operatively connected to the first track. The effector may be operatively connected to the arm. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In a further example embodiment, an apparatus for inspecting a nuclear reactor may include: a first track; an arm; a fixing device; and/or an effector. The arm may be operatively connected to the first track. The fixing device may be operatively connected to the first track. The effector may be operatively connected to the arm. The first track may include one or more motors adapted to move the arm relative to the first track. In another further example embodiment, an apparatus for performing maintenance on a nuclear reactor may include: a first track; an arm; a fixing device; and/or one or more tools. The arm may be operatively connected to the first track. The fixing device may be operatively connected to the first track. The one or more tools may be operatively connected to the arm. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In yet another further example embodiment, an apparatus for performing maintenance on a nuclear reactor, the apparatus comprising: a first track; an arm; a fixing device; and/or one or more tools. The arm may be operatively connected to the first track. The fixing device may be operatively connected to the first track. The one or more tools may be operatively connected to the arm. The first track may include one or more motors adapted to move the arm relative to the first track. In still another further example embodiment, an apparatus for repairing a nuclear reactor may include: a first track; an arm; a fixing device; one or more sensors; and/or one or more tools. The arm may be operatively connected to the first track. The fixing device may be operatively connected to the first track. The one or more sensors, the one or more tools, or the one or more sensors and the one or more tools may be operatively connected to the arm. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In an additional example embodiment, an apparatus for repairing a nuclear reactor may include: a first track; an arm; a fixing device; one or more sensors; and/or one or more tools. The arm may be operatively connected to the first track. The fixing device may be operatively connected to the first track. The one or more sensors, the one or more tools, or the one or more sensors and the one or more tools may be operatively connected to the arm. The first track may include one or more motors adapted to move the arm relative to the first track. In another additional example embodiment, a kit for inspecting, performing maintenance on, or repairing a nuclear reactor may include: a first track; an arm; and/or a fixing device. The arm may be adapted to be operatively connected to the first track. The fixing device may be adapted to be operatively connected to the first track. The arm may have a contracted length. The arm may have an expanded length. The expanded length may be greater than two times the contracted length. In yet another additional example embodiment, a kit for inspecting, performing maintenance on, or repairing a nuclear reactor may include: a first track; an arm; and/or a fixing device. The arm may be adapted to be operatively connected to the first track. The fixing device may be adapted to be operatively connected to the first track. The first track may include one or more motors adapted to move the arm relative to the first track. Example embodiments will now be described more fully with reference to the accompanying drawings. Embodiments, however, may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope to those skilled in the art. It will be understood that when a component is referred to as being “on,” “connected to,” “coupled to,” or “fixed to” another component, it may be directly on, connected to, coupled to, or fixed to the other component or intervening components may be present. In contrast, when a component is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly fixed to” another component, there are no intervening components present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments. Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like may be used herein for ease of description to describe one component and/or feature relative to another component and/or feature, or other component(s) and/or feature(s), as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Reference will now be made to example embodiments, which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like components throughout. FIG. 2 is a perspective view of an inspection, maintenance, and repair apparatus for nuclear reactors, according to an example embodiment. As shown in FIG. 2, apparatus 200 for inspection, maintenance, and/or repair of nuclear reactors may include: arm 202, first track 204, fixing device 206, and/or effector 208. Arm 202 may be operatively connected to first track 204. Fixing device 206 may be operatively connected to first track 204. Effector 208 may be operatively connected to arm 202. Apparatus 200 may allow a reduced number of movements for full or limited coverage of inspection, maintenance, and/or repair. At least partially as a result, apparatus 200 may shorten inspection cycles and/or simplify inspection plans. Arm 202 may have a contracted length and an expanded length. The expanded length may be greater than two times the contracted length. For example, the expanded length may be about 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, or more times the contracted length. In addition or in the alternative, first track 204 may include one or more motors adapted to move arm 202 relative to first track 204. Arm 202 may be adapted to move relative to first track 204. For example, arm 202 may be adapted to move along first track 204, to move relative to operative connection 210 of arm 202 to first track 204, and/or to rotate relative to first track 204. Effector 208 may include one or more sensors. For example, the one or more sensors may include at least one camera, at least one video camera, at least one transducer, at least one ultrasonic transducer, and/or at least one scanner. At least one of the one or more sensors may be, for example, sensitive to touch and/or pressure, moisture, temperature, pH, conductivity, and/or the presence and/or concentration of chemicals. In addition or in the alternative, effector 208 may include one or more tools, such as tools for cleaning the reactor, finding and/or retrieving reactor components, welding, and/or electrical discharge machining (“EDM”). In an example embodiment, apparatus 200 may be inserted into the reactor on the end of a long pole (not shown) connected to adapter assembly 212. The pole may be about 60 feet to about 80 feet in length, at least in part due to one or more of the distance from a workers' platform above the reactor to the reactor itself, the radiation exposure in the area of the workers' platform and the reactor, and the fact that the reactor may be substantially full of water when apparatus 200 is inserted into the reactor. One or more workers may control the pole to position the apparatus 200 as required in the reactor. That position might be, for example, between the outside of core shroud 110 and the inside of RPV 100, with first track 204, effector 208, and/or one or more of adjustable feet 214 substantially in contact with core shroud 110 and/or fixing device 206 substantially in contact with RPV 100. Apparatus 200 also may be inserted into the reactor using a remotely operated vehicle (“ROV”) (not shown), a cable/chain hoist (not shown), or similar device(s). When inserting apparatus 200 into the reactor, arm 202 may be rotated to be substantially parallel to first track 204. This parallelism may assist the one or more workers in expeditiously positioning apparatus 200 in the reactor. In an example embodiment, once apparatus 200 is properly positioned, the one or more workers may cause fixing device 206 to exert pressure on RPV 100 to force first track 204, effector 208, and/or one or more of adjustable feet 214 to contact core shroud 110, fixing apparatus 200 in position. Apparatus 200 also may be fixed in position by fixing device 206 in the form of a mast, scan arm, or equivalent that may be, for example, connected to core shroud 110 and/or the shroud head flange (not shown), or may ride on the steam dam (not shown) of the reactor. With apparatus 200 fixed in position, effector 208 may be positioned as required using arm 202 and first track 204. For example, assuming that first track 204 is fixed in a vertical orientation, arm 202 may be moved along first track 204 to raise or lower operative connection 210 (and, thus, to raise or lower effector 208), arm 202 may be moved relative to operative connection 210 (and, thus, to change the distance of effector 208 from operative connection 210), and/or arm 202 may be rotated relative to first track 204 to change the angle of arm 202 relative to first track 204 (and, thus, to change the angular position of effector 208). The narrow profile of arm 202 and effector 208 may allow effector 208 access to confined spaces inaccessible by other devices, such as ROVs. Effector 208 may be positioned by any of these “degrees of freedom” independently or by two or more simultaneously. Additionally or in the alternative, effector 208 may have “degrees of freedom” other than those discussed above. Some examples are in included in the discussion of arm 202 below. Apparatus 200 may further include a cable management system. The cable management system helps to manage one or more umbilical cables (not shown) that, for example, may supply power (i.e., electrical, pneumatic, and/or hydraulic (water-based)) to apparatus 200, may provide control signals to apparatus 200, and/or may provide the one or more workers with sensors signals from apparatus 200. The one or more umbilical cables may reach from a workers' platform to apparatus 200 and/or effector 208. First track 204 may include at least a portion of the cable management system. Similarly, arm 202 may include at least a portion of the cable management system. In an example embodiment, first track 204 may include a first portion of the cable management system and arm 202 may include a second portion of the cable management system. FIG. 3 is an exploded, perspective view of an arm of the apparatus of FIG. 2, while FIG. 4 is a reverse exploded, perspective view of the arm of FIG. 3. As shown in FIGS. 3 and 4, arm 202 may include second track 300; crossbar 302; guide block 304; guides 306 and/or 308; roller brackets 310, 312, and/or 314; rollers 316, 318, and/or 320; and/or effector bracket 322. Second track 300 may include three or more sections. Typically, because the sections are stacked, more sections results in a thicker second track 300. Sections of second track 300 may be manufactured with a standardized radius of curvature or standardized radii of curvature. However, the radius of curvature of second track 300 does not need to exactly match that of core shroud 110, RPV 100, etc. This may be true, for example, if effector 208 does not have to be in direct contact with core shroud 110, RPV 100, etc. In addition or in the alternative, this may be true because effector 208 may be operatively connected to arm 202 using effector bracket 322, and effector bracket 322 may be spring-loaded or equivalent to influence effector 208 toward core shroud 110, RPV 100, etc. In an example embodiment, crossbar 302 may function primarily as a structural support. In addition to the degrees of freedom discussed above, effector 208 may have additional degrees of freedom. For example, effector 208 may be operatively connected to arm 202 using a gimbal or some other device. In an example embodiment, effector 208 may be operatively connected to arm 202 anywhere on arm 202. As discussed above, arm 202 may include at least a portion of the cable management system. That portion may include, for example, one or more of guide block 304; guides 306 and/or 308; roller brackets 310, 312, and/or 314; and rollers 316, 318, and/or 320. FIG. 5 is a front perspective view of second track 300 of arm 202 of FIG. 3, FIG. 6 is a top view of second track 300 of FIG. 5, and FIG. 7 is a rear view of second track 300 of FIG. 6. FIG. 8 is a first detailed view of second track 300 of FIG. 7, FIG. 9 is a second detailed view of second track 300 of FIG. 7, and FIG. 10 is a third detailed view of second track 300 of FIG. 7. As shown in FIGS. 5-9, second track 300 may include first section 500, second section 502, third section 504, and/or fourth section 506. Fourth section 506 may be fixed to first track 204. First section 500 may include backbone 900, upper gear rack 902, upper rail 904, and/or lower rail 906. Second section 502 may include backbone 908, lower gear rack 910, one or more inner rollers 912, and/or one or more outer rollers 914. Third section 504 may include backbone 916, inner upper gear rack 918, outer upper gear rack 920, inner upper rail 922, inner lower rail 924, outer upper rail 926, and/or outer lower rail 928. Fourth section 506 may include backbone 930, lower gear rack 932, and/or one or more rollers (not shown). In FIG. 9, upper rail 904 and lower rail 906 of first section 500 are depicted as v-shaped rails. Although other shapes are possible, one or more inner rollers 912 of second section 502 ride on one or both of upper rail 904 and lower rail 906. Similarly, inner upper rail 922 and inner lower rail 924 of third section 504 are depicted as v-shaped rails. Although other shapes are possible, one or more outer rollers 914 of second section 502 ride on one or both of inner upper rail 922 and inner lower rail 924. In the same way, outer upper rail 926 and outer lower rail 928 of third section 504 are depicted as v-shaped rails. Although other shapes are possible, one or more rollers (not shown) of fourth section 506 ride on one or both of outer upper rail 926 and outer lower rail 928. Upper gear rack 902 and inner upper gear rack 918 may be connected by a first idler gear (not shown) so that when second track 300 is expanded or contracted by the driving of outer upper gear rack 920, first section 500 is driven by third section 504. Similarly, lower gear rack 910 and lower gear rack 932 may be connected by a second idler gear (not shown) so that when second track 300 is expanded or contracted by the driving of outer upper gear rack 920, second section 502 is driven by fourth section 506. In this way, when second track 300 is expanded or contracted by the driving of outer upper gear rack 920, first section 500, second section 502, and third section 504 may all move simultaneously relative to fourth section 506. In a first example embodiment, the extent of this simultaneous movement is proportional between sections. In a second example embodiment, the extent of the simultaneous movement is identical between sections. FIG. 8 shows rail adjuster 800 attached to first section 500. FIG. 10 shows rail adjuster 1000 attached to third section 504. Such rail adjusters allow mechanical adjustments to the tension between an upper and lower rail pair (i.e., between upper rail 904 and lower rail 906 of first section 500). In another example embodiment, apparatus 200 for inspection, maintenance, and/or repair of nuclear reactors may include: arm 202, first track 204, fixing device 206, and/or effector 208. Arm 202 may include a second track with a curvature opposite to that of second track 300. In this case, the apparatus 200 may be positioned, for example, between the outside of core shroud 110 and the inside of RPV 100, with first track 204, effector 208, and/or one or more of adjustable feet 214 substantially in contact with RPV 100 and/or fixing device 206 substantially in contact with core shroud 110. The apparatus 200 may be used, for example, to inspect the inner surface of RPV 100. In a further example embodiment, apparatus 200 for inspection, maintenance, and/or repair of nuclear reactors may include: arm 202, first track 204, fixing device 206, and/or effector 208. Arm 202 may include a second track that is substantially straight. In this case, the apparatus 200 may be used, for example, to inspect any substantially flat surface in the reactor. In yet another example embodiment, apparatus 200 for inspection, maintenance, and/or repair of nuclear reactors may include: arm 202, first track 204, fixing device 206, and/or effector 208. Arm 202 may include one or more second tracks. At least one of the one or more second tracks may be a curved track. In addition or in the alternative, at least one of the one or more second tracks may be a substantially straight track. In addition or in the alternative, at least one of the one or more second tracks may include at least three sections. In an example embodiment, the at least three sections may be are adapted to contract arm 202 to the contracted length and/or to expand arm 202 to the expanded length. FIG. 11 is an exploded, perspective view of first track 204 of apparatus 200 of FIG. 2, while FIG. 12 is a reverse exploded, perspective view of first track 204 of FIG. 11, FIG. 13 is a reverse exploded, perspective view of a first portion of first track 204 of FIG. 11, and FIG. 14 is a reverse exploded, perspective view of a second portion of first track 204 of FIG. 11. As shown in FIGS. 11-14, first track 204 may include first motor 1200, second motor 1202, and/or third motor 1204. First track 204 also may include first shaft 1206, second shaft 1208, and/or third shaft 1210. Additionally, first track 204 may include first rail 1212 and/or second rail 1214. Other components of first track 204 may include case 1216, motor box 1218, motor box cap 1220, top support plate 1222, top support side plate 1224, rotation block assembly 1226, cable guard 1228, cable guides 1230 and 1232, pulleys 1234 and 1236, dual pulley assembly 1238; and/or gear 1240. Gear 1240, associated with rotation block assembly 1226, may be best seen in FIGS. 3 and 11. Additionally, first track 204 may include extra components known to one of skill in the art (as shown in FIGS. 11-14), such as, for example, one or more ball bearings, brackets, cable guides, caps, drive gears, gaskets, idler gears, lock nuts, miter gears, pinions, screws, seals, shaft extensions, spacers, washers, and worm gears. In an example embodiment, first track 204 includes three gears—a pinion gear, an idler gear, and a worm gear—for each of first motor 1200, second motor 1202, and third motor 1204 (the motor turns the pinion gear, the pinion gear turns the idler gear, and the idler gear turns the worm gear). In a first example embodiment, first track 204 may include one or more motors (i.e., first motor 1200, second motor 1202, and/or third motor 1204) adapted to move arm 202 relative to first track 204. In a second example embodiment, first track 204 may include one or more motors adapted to move arm 202 along first track 204. In a third example embodiment, first track 204 may include one or more motors adapted to move arm 202 relative to operative connection 210. In a fourth example embodiment, first track 204 may include one or more motors adapted to rotate arm 202 relative to first track 204. In a fifth example embodiment, first track 204 may include first motor 1200, second motor 1202, and third motor 1204, wherein first motor 1200 is adapted to move arm 202 relative to operative connection 210, wherein second motor 1202 is adapted to move arm 202 along first track 204, and wherein third motor 1204 is adapted to rotate arm 202 relative to first track 204. As discussed above, first track 204 may include at least a portion of the cable management system. That portion may include, for example, one or more of cable guard 1228, cable guides 1230 and 1232, pulleys 1234 and 1236, and/or dual pulley assembly 1238, as well as some of the extra components known to one of skill in the art listed above. In an example embodiment, the umbilical cable of the cable management system passes between cable guide 1230 and pulley 1234, then passes between cable guide 1232 and pulley 1236, then passes through first track 204 to dual pulley assembly 1238, then under guide block 304 and around one or both of guides 306 and 308, and then to effector 208, optionally contacting one or more of rollers 316, 318, and 320. In a first example embodiment, tension is maintained on the umbilical cable that passes between cable guide 1230 and pulley 1234. In a second example embodiment, the tension is kept substantially constant. In a third example embodiment, the tension is kept substantially constant using a snatch-block arrangement. First motor 1200 and first shaft 1206 may drive arm 202 to move relative to operative connection 210. This movement may be to expand arm 202 (i.e., to unstack first section 500, second section 502, third section 504, and fourth section 506), or the movement may contract arm 202 (i.e., to stack first section 500, second section 502, third section 504, and fourth section 506). In an example embodiment, arm 202 may expand to either one side or the other of operative connection 210, providing additional flexibility in the use of apparatus 200. As discussed above, second track 300 may include three or more sections. For example, second track 300 may include three, four, five, six, seven, eight, or more sections. The number of sections may be odd or even. The number of sections that can be used is essentially a function of the strength of the materials used to construct second track 300, first rail 1212, and second rail 1214 (first rail 1212 and second rail 1214 support substantially the entire load of expanded second track 300 to effectively prevent this load from impacting the performance of first shaft 1206, second shaft 1208, and/or third shaft 1210 and, hence, the performance of first motor 1200, second motor 1202, and/or third motor 1204). Second motor 1202 and second shaft 1208 may drive arm 202 to move along first track 204. This “vertical” movement may be guided by first rail 1212 and/or second rail 1214. Third motor 1204 and third shaft 1210 may drive arm 202 to rotate relative to first track 204. The drive train also may include, for example, gear 1240. The rotation may be in either a clockwise or counterclockwise sense. Thus, arm 202 may be driven in rotation to any angular position relative to first track 204. As discussed above, when inserting apparatus 200 into the reactor (and also when removing apparatus 200 from the reactor), arm 202 may be rotated to be substantially parallel to first track 204. Arm 202 may be driven individually by first motor 1200/first shaft 1206, second motor 1202/second shaft 1208, or third motor 1204/third shaft 1210. In addition or in the alternative, arm 202 may be simultaneously driven by any combination of first motor 1200/first shaft 1206, second motor 1202/second shaft 1208, and/or third motor 1204/third shaft 1210. FIG. 15 is a perspective view of fixing device 206 of apparatus 200 of FIG. 2, while FIG. 16 is a reverse perspective view of fixing device 206 of FIG. 15. As shown in FIGS. 15 and 16, fixing device 206 may include base 1500, plurality of legs 1502, and/or one or more pneumatic or hydraulic pistons 1504. Advantageously, the fixing device 206 of FIGS. 15 and 16 may expand from a single driven point. The one or more pneumatic or hydraulic piston 1504 may be positioned, oriented, and/or connected to base 1500 and/or plurality of legs 1502 in a variety of configurations, as is known to one of ordinary skill in the art. In a first example embodiment, fixing device 206 may be a scissor jack. In a second example embodiment, fixing device 206 may include one or more scissor jacks. In a third example embodiment, fixing device 206 may include one or more hydraulic cylinders and/or one or more pneumatic cylinders. In a fourth example embodiment, fixing device 206 may include one or more hydraulic pistons and/or one or more pneumatic pistons. Typically, hydraulic systems in a reactor are water-based, and hydraulic and pneumatic systems must meet strict cleanliness and purity controls. In another first example embodiment, a method of inspecting a nuclear reactor may include: operatively connecting a fixing device, a first track, an arm, and an effector to form an inspection apparatus; inserting the inspection apparatus into the reactor; fixing the inspection apparatus within the reactor; and operating the inspection apparatus. In another second example embodiment, a method of operating a nuclear reactor may include: shutting down the nuclear reactor; inspecting the nuclear reactor, as discussed above; and starting up the nuclear reactor. In another third example embodiment, a method of performing maintenance on a nuclear reactor may include: operatively connecting a fixing device, a first track, an arm, and one or more tools to form a maintenance apparatus; inserting the maintenance apparatus into the reactor; fixing the maintenance apparatus within the reactor; and operating the maintenance apparatus. In another fourth example embodiment, a method of operating a nuclear reactor may include: shutting down the nuclear reactor; performing maintenance on the nuclear reactor, as discussed above; and starting up the nuclear reactor. In another fifth example embodiment, a method of repairing a nuclear reactor may include: operatively connecting a fixing device, a first track, an arm, and one or more sensors, one or more tools, or one or more sensors and one or more tools to form a repair apparatus; inserting the repair apparatus into the reactor; fixing the repair apparatus within the reactor; and operating the repair apparatus. In another sixth example embodiment, a method of operating a nuclear reactor may include: shutting down the nuclear reactor; repairing the nuclear reactor, as discussed above; and starting up the nuclear reactor. In each of these six example embodiments, the arm may have a contracted length and an expanded length, and the expanded length may be greater than two times the contracted length. While example embodiments have been particularly shown and described, it will be understood by those of ordinary skill in the art that various changes in form and details may be made in the example embodiments without departing from the spirit and scope of the present invention as defined by the following claims.
	summary
048256471	claims	1. An optimized performance thruster assembly comprising: (a) a housing including a first opening and a second opening; (b) a heating element removably mounted in said first opening; (c) a propellant supply conduit extending through wall means defining said housing; (d) nozzle means adjacent said second opening; (e) propellant supply passageway means conducting propellant from said propellant supply conduit to said nozzle means; (f) heat exchange means for transmitting heat generated by said heating element to said propellant in said propellant supply passageway means and in said nozzle means, said heat exchange means isolating said heating element from direct contact with said propellant; (g) shielding means substantially surrounding said heating element and focusing the majority of heat generated by said heating element in a direction generally toward said nozzle, said shielding means comprising a plurality of discs mounted on said heating element in spaced relation to one another axially along said heating element, said discs being spaced from one another by at least one rod extending through all of said discs and mounted to said heating element, said at least one rod including resilient biasing means thereon resiliently separating adjacent discs, and cylindrical members attached to at least some of said discs, said cylindrical members extending axially of said heating element; and (h) said propellant being expelled out said second opening via said nozzle means to provide thrust. (a) a fluid inlet; (b) a mixing chamber downstream of said fluid inlet; (c) an injection orifice downstream of said mixing chamber; and (d) said decomposition chamber downstream of said injection orifice. (a) a first substantially cylindrical body; (b) a screw thread-like open passageway formed in an outer surface of said first body; (c) a second substantially cylindrical body concentrically mounted over said first body and having an inner wall; and (d) said second passageway being defined by said screw thread-like open passageway and said inner wall. (a) a plurality of concentric cylinder members; (b) a disc attached to one end of each said cylinder members; and (c) means spacing said discs and cylinder members apart. (a) rod means extending through said discs; and (b) spacers mounted on said rod means between said discs. (a) a housing including a first opening and a second opening; (b) a heating element removably mounted in said first opening; (c) a propellant supply conduit extending through wall means defined in said housing and including means for maintaining said propellant at a temperature below the vaporization temperature thereof until said propellant enters a decomposition chamber within said propellant supply conduit, said means for maintaining also preventing adherence of residues to said propellant supply passageway means, said means for maintaining comprising: (d) nozzle means adjacent said second opening; (e) propellan supply passageway means conducting propellant from said propellant supply conduit to said nozzle means; (f) heat exchange means for transmitting heat generated by said heating element to said propellant in said propellant supply passageway means and in said nozzle means, said heat exchange means isolating said heating element from direct contact with said propellant; (g) shielding means substantially surrounding said heating element and focusing the majority of heat generated by said heating element in a direction generally toward said nozzle; and (h) said propellant being expelled out said second opening via said nozzle means to provide thrust. 2. The invention of claim 1, wherein said heating element comprises a coil which generates radiant heat energy. 3. The invention of claim 2, wherein said heating element further includes an emissive stage enabling the generation of emissive heat energy. 4. The invention of claim 1, wherein said propellant supply conduit includes means for maintaining said propellant at a temperature below the vaporization temperature thereof until said propellant enters a decomposition chamber within said propellant supply conduit, said means for maintaining also preventing adherence of residues to said propellant supply passageway means. 5. The invention of claim 4, wherein said means for maintaining comprises: 6. The invention of claim 5, wherein said mixing chamber includes a plurality of wires mounted therein and extending thereacross, said wires facilitating propellant mixing and carrying heat energy away from said propellant. 7. The invention of claim 6, wherein said wires are made of tungsten-rhenium. 8. The invention of claim 5, wherein said decomposition chamber includes screen pack means for decomposing said propellant, said decomposition chamber connecting said propellant supply conduit with said propellant supply passageway means. 9. The invention of claim 1, wherein said propellant supply passageway means includes a first passageway adjacent said wall means and a second passageway adjacent said heating element but separated therefrom by said heat exchange means, said first and second passageways being fluidly connected with one another. 10. The invention of claim 9, wherein said first passageway is connected to said propellant supply conduit and said second passageway conducts said propellant to said nozzle means. 11. The invention of claim 10, wherein said second passageway comprises: 12. The invention of claim 11, wherein said screw thread-like open passageway defines land means, said land means being brazed to said inner wall. 13. The invention of claim 12, wherein one of molybdenum or iridium is utilized to braze said land means to said inner wall. 14. The invention of claim 11, wherein said first passageway comprises a coiled tube. 15. The invention of claim 11, wherein said screw threads are provided with a radius of curvature designed so as to impart centrifugal force to said propellant of sufficient value at flow rates resulting in laminar flow to thereby create, in addition to the primary axial flow path of propellant therethrough, a secondary flow path of propellant within said screw threads, said secondary flow path being directed in raidal directions in said screw threads and recirculating propellant from central portions of said screw threads to peripheral portions thereof. 16. The invention of claim 14, wherein said coiled tube has interior surfaces thereof coated with one of iridium, tungsten or rhenium. 17. The invention of claim 10, wherein said first passageway comprises a coiled tube and said second passageway comprises a further coiled tube. 18. The invention of claim 17, wherein said coiled tube has interior surfaces thereof coated with one of iridium, tungsten or rhenium. 19. The invention of claim 15, wherein said second passageway comprises a further coiled tube, mounted in said housing substantially concentrically within said first passageway. 20. The invention of claim 19, wherein said further coiled tube has interior surfaces thereof coated with one of iridium, tungsten or rhenium. 21. The invention of claim 18, wherein said coiled tube and said further coiled tube are provided with radii of curvature designed so as to impart centrifugal force to said propellant of sufficient value at flow rates resulting in laminar flow to thereby create, in addition to the primary axial flow path of propellant therethrough, a secondary flow path of propellant directed in radial directions and recirculating propellant from central portions of said coiled tube and said further coiled tube to peripheral portions thereof. 22. The invention of claim 1, wherein said first opening opens to a heating chamber wherein said heating element is mounted, said heating chamber having mounted therein an energy absorbing component forming a part of said heat exchange means which focuses energy transmitted by said heating element to said nozzle means. 23. The invention of claim 22, wherein said energy absorbing component includes a plurality of concentric cylinders brazed to a disc connected to a wall of said heating chamber. 24. The invention of claim 22, wherein said energy absorbing component includes a spiral-like scroll member having an edge thereof brazed to a disc connected to a wall of said heating chamber. 25. The invention of claim 22, wherein said nozzle means includes a nozzle heat exchange component as an integral part thereof which forms a part of said heat exchange means. 26. The invention of claim 25, wherein said nozzle heat exchange component includes a plurality of walls which form a fuel passageway between said propellant supply passageway means and said second opening. 27. The invention of claim 26, wherein said plurality of walls comprises a spiral wall. 28. The invention of claim 26, wherein said plurality of walls comprises a plurality of concentric cylinders with gaps at alternative ends thereof so as to form said fuel passageway. 29. The invention of claim 26, wherein said energy absorbing component is mounted on a chamber wall having one surface facing said heating chamber, said chamber wall having a further surface adjacent said one surface and facing said nozzle means, said nozzle heat exchange component being mounted on said further surface. 30. The invention of claim 1, wherein said shielding means is connected to said heater element in a manner so as to minimize the contact areas therebetween to thereby minimize heat exchange between said shielding means and heater element and to thereby maximize focusing of said heat generated by said heating element onto said heat exchange means. 31. The invention of claim 1, wherein said discs are spaced from one another by a plurality of rods each corresponding to said at least one rod. 32. The invention of claim 31, wherein said biasing means comprises springs mounted on said rods between adjacent discs. 33. The invention of claim 1, wherein said first opening opens to a heating chamber wherein said heating element is mounted, said shielding means extending substantially the full length of said heating chamber. 34. The invention of claim 1, wherein said first opening opens to a heating chamber wherein said heating element is mounted, said heating chamber having mounted therein an energy absorbing component forming a part of said heat exchange means which focuses energy transmitted by said heating element to said nozzle means. 35. The invention of claim 34, wherein said nozzle means includes a nozzle heat exchange component as an integral part thereof which forms a part of said heat exchange means. 36. The invention of claim 35, wherein said energy absorbing component is mounted on a chamber wall having one surface facing said heating chamber, said chamber wall having a further surface adjacent said one surface and facing said nozzle means, said nozzle heat exchange component being mounted on said further surface. 37. The invention of claim 1, further including further shielding means mounted within said housing for reducing power losses from said housing comprising: 38. The invention of claim 37, wherein said spacing means comprises: 39. The invention of claim 38, wherein said rod means extends through holes formed in said discs, said holes including annular beveled faces converging toward one another to form a substantially circular interface line therebetween which contacts said rod means. 40. The invention of claim 38, wherein each said spacer comprises a ring of substantially circular cross-section, said rings contacting adjacent discs with a line-type contact. 41. The invention of claim 5 wherein said decomposition chamber includes heat exchanger means for pre-heating said propellant, said decomposition chamber connecting said propellant supply conduit with said propellant supply passageway means. 42. An optimized performance thruster assembly comprising:
	description	As shown in the exemplary drawings, the preferred embodiment of the present invention comprises a radiopharmaceutical pig 10 and a sharps container 12 for a syringe 14 holding a radioactive drug. The syringe holding the radioactive drug fits within the sharps container, which, in turn, fits within the radiopharmacetcal pig. The sharps container may be designed to meet U.S. government regulations, such as 29 C.F.R. xc2xa71910.1030, for protective containers that house materials having biologically contaminated sharp edges. However, the sharps container design could be modified depending on a particular application. FIGS. 1, 2, and 4 show the relationship between the components of the radiopharmaceutical pig 10 and the sharps container 12. The radiopharmaceutical pig has a tubular upper shield 16 that screws onto a tubular lower shield 18. the sharps container nests within the upper shield and lower shield. Likewise, the sharps is comprised of a lower insert 20 and an upper cap 22 that cooperatively enclose the syringe 14. The upper shield 16 of the radiopharmaceutical pig 10 has a generally tubular shape and has a closed end 24 and an open end 26. The lower shield 18 has a generally tubular shape and has a closed end 28 and an open end 30. Both shields have internal cavities 32 and 34 sized to accept at least a portion of the sharps container 12. The upper and lower shields are preferably constructed of tungsten, but any radiation-resistant material may be used, depending on the desired application. The open end 26 of the upper shield 16 connects to the open end 30 of the lower shield 18 when the radiopharmaceutical pig 10 is assembled. Referring now to FIGS. 1, 2, 4, and 6, the upper shield of the radiopharmaceutical pig has a main body portion 36 and a flanged end portion 38. The main body portion is tubular and has a threaded area 40 on the external surface of its lower end 42. Preferably, the flanged end portion has two open ends 44 and 46 and a passageway 50 therebetween with an inside diameter at least as large as the external diameter of the main body portion. The upper area of the internal passageway of the flanged end portion has threads 52 configured to engage the threads on the main body portion. A waterproof adhesive or sealant can be put on or between these threads to provide for a permanent, secure connection between the main body portion and the flanged end portion. (Other means of attachment could be used, such as welding or other mechanical fasteners, or the flanged end portion may be integrally formed to the main body portion. The lower portion of the passageway of the flanged body portion also has threads 54 configured to engage external threads 56 on the open end 30 of the lower shield, as described below. The flanged end portion may also have wrench flats 59 for use in preventing the rolling of the radiopharmaceutical pig and/or tightening the upper shield to the lower shield. Lastly, the bottom inside edge of the flanged end portion defines a channel 58 to accommodate an O-ring 60 to provide a seal between the upper and lower shields. Finally, a tubular plastic grip 62 is mounted on the closed end 24 of the upper shield 16. The grip may be mounted by press fit, with adhesive, or mechanical fasteners. The grip has external channels 64 to facilitate gripping of the container by users. The grip also functions as a shield to protect the upper shield from impacts that could crack or damage it. The tubular grip may be made from plastic or rubber, including PVC material. The lower shield 18 preferably is comprised of three pieces: a tubular body 66, an upper circular flange 68, and a lower end-cap 70. The tubular body has openings on both ends 72 and 74 and a passageway 76 therebetween sized to accept at least a portion of the syringe 14 and/or the sharps container 12 therein. The tubular body has an upper end 72 with a circular wall 78 extending upwardly therefrom to contact an upper ridge 120 on the sharps container insert 20, as will be described below. The upper end of the tubular body also has external threads 82 configured to engage threads 84 on the inside surface of the circular flange. The cross-section of the circular flange is xe2x80x9cLxe2x80x9d shaped and may have a circular indentation 86 to accept a portion of the O ring 60 therein. The upper portion of the circular flange 8 has external threads 56 configured to engage the threads 54 on the inside of the flanged end portion 38 of the upper shield 16. Wrench flats 87 may be formed on the outside edge of the flange. When assembled, the lower end 26 of the flanged end portion abuts an upper surface 88 located on the horizontal leg of the xe2x80x9cLxe2x80x9d shaped circular flange. The threads described herein may be connected with adhesive or other mechanical or chemical ways of mounting the components together may be used, as is appropriate for a particular application. The end cap 70 forming the lower portion of the lower shield 18 is tubular and has a shape similar to the body portion 36 of the upper shield 16. The end cap defines an internal cavity 90 having diameter lesser than that of the lower body 66 of the lower shield. The lower end of the passageway 76 in the body portion has internal threads 92 configured to engage external threads 94 located on the upper portion of the end cap. The cavity in the end cap may be smaller because it may only need to accommodate the narrower portions of the syringe 14. Because less radiation-resistant material is needed to manufacture the end cap, it is believed to be more cost effective to form the lower shield from the body and the end cap, as compared to a one-piece shield having a uniform diameter throughout its entire length. A tubular plastic base 96 is mounted on the lower end of the lower shield 18. The base may be made of the same material as the plastic grip 62 mounted on the upper shield 16. Channels 98 are formed in the outer surface of the base to facilitate gripping by healthcare workers for the assembly and dis-assembly of the radiopharmaceutical pig 10. The base may be mounted to the lower shield by a press fit, with adhesive, or mechanical fasteners. The base also protects the lower shield from impacts that could cause cracks or other damage. The base has an enlarged lower end 100 sized to stabilize the radiopharmaceutical pig 10 when it is placed on a table top or other work surface. The syringe 14 has a generally tubular body 102 with a flanged base 104, a hypodermic needle 106, a cap 108, and a plunger 110. The body and needle of the syringe nest within the sharps container housing 20. The plunger fits within the upper shield 16 and the sharps container cap 22. The radiopharmacuetical pig 10 can be configured to hold syringes of various sizes, including those well known in the medical arts. Referring now to FIGS. 1, 3, and 5, the cap 22 of the sharps container 12 preferably has a tubular, cup-like shape to accommodate the plunger 110 of the syringe 14. Likewise, the sharps container housing 20 has a tubular shape to accommodate the body 102 and needle 106 of the syringe. In the alternative or in combination with the cap 22, a similar, but shorter cap 112 may be used. The external dimensions of the caps 22 and 112 and the housing of the sharps container are sized so that they will nest within the upper 16 and lower 18 shields of the radiopharmaceutical pig 10. Each cap 22 and 112 has a closed end 114 and an open mating end 116 with an inwardly projecting circumferential ridge 118 that will deform as it slides downwardly over an outwardly projecting circumferential ridge 120 on the upper end of the housing 20. Likewise, the ridge 120 on the housing may deform when the ridge 118 of the cap moves downwardly past the ridge on the housing. Each of the ridges has a beveled surface 122 so that the ridges may deform and pass by each other to snap the cap onto the housing. If only the smaller cap 112 is used with the housing for a particular application, cost savings should result because less material is required to make each cap and the lighter-weight caps should cost less to ship. The caps 22 and 112 of the sharps container 12 may be made from a red-colored polypropylene, PVC, or other plastic material. If the sharps container is intended to comply with certain U.S. government regulations, e.g., 29 C.F R. xc2xa71910.1030, it should be labeled appropriately, such as having a red color, to signify that the sharps container contains regulated medical waste. Another way of satisfying this regulation is by labeling the sharps container with the word xe2x80x9cbiohazardxe2x80x9d or the well known international biohazard symbol. The housing 20 of the sharps container 12 nests within the cavity 34 of the lower shield 18. The housing has a closed end 124, an open mating end 126, and an interior surface that defines an interior cavity 128. The open mating end of the housing has its circumferential ridge 120 that engages the corresponding ridge 118 on either one of the caps 22 and 112. The ridge in the housing also is sized to support the flange 104 of the syringe 14 and rest upon the circular wall 78 extending upwardly from the body 66 of the lower shield 18. The hollow tubular housing is preferably made from a transparent polystyrene or other plastic material. Because the housing material is transparent, the interior of the housing can be viewed without disassembly of the sharps container. The entire housing need not be transparent, rather, the housing may be made from an opaque material having a small, transparent window that provides a view of the interior. The housing also need not be constructed of a transparent material if the contents of the sharps container can be ascertain by other means, such as by the appropriate labeling of the exterior of the sharps container. The housing and the caps may also be constructed from other materials of suitable strength. The circumferential ridge 118 on the sharps container housing 20 is sized to support the flanged base 104 of the syringe body 102, to support the syringe 14 so that its needle 106 and body are within the cavity 128 of the housing. Because the flanged base of the syringe rests on the ridge of the housing, the syringe is easily inserted with the needle pointing toward the closed end of the housing. Therefore, the fit between the shoulder of the housing and the flanged base of the syringe facilitates placement of the syringe into a position where the needle is immediately shielded within the housing. If the syringe is placed into the housing with its needle pointing upward, the needle poses a threat to persons trying to affix the cap 22 to the housing. Such persons are discouraged from such placement of the syringe because the syringe does not easily rest on the ridge of the housing when it is in such a reversed position. Futhermore, the sharps container 12 cannot be closed with the syringe pointing upward because the caps 22 and 112 preferably are not long enough to accommodate the body 102 and the needle of the syringe. Accordingly, the sharps container is advantageously configured to encourage the placement of the syringe with its needle safely protected within the housing. The caps 22 and 112 and the housing 20 of the sharps container 12 resist the leakage of the radioactive drug, blood, or other contaminates from within the sharps container. As shown in FIG. 6, the O ring 60 likewise provides a seal between the upper and lower shields 16 and 18 of the radiopharmaceutical pig 10. Together, the radiopharmaceutical pig 10 and the sharps container 12 can be used to transport and dispose of the syringe 14 without contamination concerns. When a patient needs a dose of a radioactive drug, a healthcare worker, such as a doctor or nurse, transmits a prescription to a pharmacy, where the required drug is packaged in a syringe, using well known medical practices. A label containing information regarding the drug is preferably affixed to the body 102 of the syringe. The following information may be included on the label: the patient""s name, the production lot number, the expiration date of the drug, the quantity of the drug, the name of the intended medical procedure, and possibly other relevant information, such as a relevant order number or the drug""s radioactive half life. A larger label with similar information also may be affixed to the radiopharmaceutical pig 10. The labels for the syringe and the radiopharmaceutical pig may contain any suitable information, such as words, bar code, or color code. It should be understood that the invention is not limited by the method of encoding and decoding the information contained on the labels, nor by the actual content of the information on the labels. After the radioactive drug is packaged within the syringe 14 at the pharmacy, the sharps container housing 20 may be placed within the inner cavity 34 of the lower shield 18 of the radiopharmaceutical pig 10. The syringe is then placed into the inner cavity 128 of the sharps container housing so that its capped needle 106 projects toward the closed end 124 of the housing. The larger cap 22 of the sharp container 12 may then be attached to the housing to prevent the syringe contents from contaminating the radiopharmaceutical pig. After the syringe has been used at the hospital, the larger cap 22 may be replaced upon the insert to enclose the spent syringe. Alternatively, the sharps container may not be used to deliver the syringe to the location for use if the pharmacy is content to rely upon the capped needle to prevent contamination of the radiopharmaceutical pig. In another alternative arrangement, the hospital may have a pre-ordered supply of large 22 or small 112 caps for use in enclosing spent syringes. In another embodiment, the short cap could be transported with the radiopharmaceutical pig from the pharmacy. Next, the upper shield 16 of the radiopharmaceutical pig 10 is positioned above the lower shield 18 of the radiopharmaceutical pig so that the mating ends 26 and 30 of the upper and lower shields are in opposed alignment. The upper and lower shields are then moved together and rotated until the threads 54 of the upper shield engage the threads 56 of the lower shield. As shown in FIG. 2, the now-assembled radiopharmaceutical pig contains the sharps container 12 and the syringe 14 containing the radioactive drug. Once the upper portion 16 and the lower portion 18 of the radiopharmaceutical pig 10 have been joined, the radiopharmaceutical pig is placed in a shipping container (not shown) that may need to meet government regulations for the transportation of radioactive substances. The shipping container may be transported to the destination of use (most likely a hospital) via motor vehicle, aircraft, hand cart, bicycle, or other delivery method. When the syringe 14 is needed for use, the radiopharmaceutical pig 10 is removed from the shipping container and the upper portion 16 is unscrewed from the lower portion 18, to expose the cap 22 or 112 of the sharps container 12. The cap may be conveniently pulled off of the housing 20 to expose the syringe. The syringe may be easily removed by use of well known safety procedures. The syringe may then be used to inject the patient, thereby discharging the radioactive drug from the syringe. After the injection, the syringe may be biologically contaminated and likely will contain a small amount of residual radioactive drug. After the injection, the spent syringe 14 is inserted into the inner cavity 128 of the housing 20 of the sharps container 12. The shorter sharps container cap 112 may then be placed over the syringe plunger 110, so that the cap""s mating end 116 is in opposed alignment with the mating end 126 of the housing 20. The cap is then moved towards the housing until the circumferential ridges 118 and 120 snap past each other to attach the cap to the housing. Alternatively, the larger cap 22 may be affixed to the housing to enclose the spent syringe. It should be appreciated that the ridges 118 on the caps 22 and 112 and the housing 20 of the sharps container 12 need not be in a precise alignment in order to connect the cap to the housing. Therefore, a healthcare worker may conveniently put the cap on the housing without bothering to align any clips on a cap with any receptacles on the housing, as is the case with at least one conventional radiopharmaceutical pig and sharps container combination. This feature is intended to save time and allow the worker to focus attention on other more important matters. After the spent syringe 14 is safely contained within the sharps container 12, the radiopharmaceutical pig 10 is assembled by threadably engaging the upper and lower portions 16 and 18 so that the sharps container is enclosed inside the radiopharmaceutical pig. The assembled radiopharmaceutical pig is placed in a shipping container for transport to the disposal area, which may be at the pharmacy. The shipping container is transported to the disposal area where the radiopharmaceutical pig is disassembled by threadably removing the upper portion from the lower portion. When the upper portion of the radiopharmaceutical pig has been removed, the cap 22 or 112 of the sharps container is exposed because it extends upward from the lower portion of the radiopharmaceutical pig. The sharps container is then removed, which allows the label on the syringe to be read through the transparent housing 20. The information on the label enables a disposal worker to determine the proper disposal container for the syringe within the sealed sharps container. The sharps container, with the spent syringe inside, is disposed of by placing in the particular disposal container for radioactive material having the half-life of the radioactive residual. A primary advantage of the device described above is that it can be handled easily because of its small size and because of the grip 62 and base 96 on the upper and lower shields 16 and 18. Also, the use of the short cap 112 can automatically inform workers that the sharps container 12 contains a spent syringe 14. Likewise, there is no plastic shell that completely encloses shields 16 and 18. Therefore, breakage concerns relating to such plastic shells are alleviated. Upon opening the radiopharmaceutical pig 10, a person is advantageously protected from the threat of an unshielded needle because the syringe is contained within the sharps container. Yet another advantage of the present invention is the prevention of the contamination of the radiopharmaceutical pig 10 during the transport of the syringe 14 from the pharmacy to the point of patient treatment. The housing 20 of the sharps container 12 advantageously prevents the inner cavity 34 of the lower shield 18 of the radiopharmaceutical pig from becoming contaminated during this trip. If the syringe leaks, the radioactive drug should collect in the housing, thereby preventing the contamination of the lower shield. An additional level of protection can be had through the use of the cap 22 during the transport of the syringe from the pharmacy to the location of use. Furthermore, once the spent syringe is sealed within the sharps container, the inner cavities 32 and 34 of the upper 16 and lower 18 shield are advantageously protected from contamination while the radiopharmaceutical pig is moved to the disposal area. Accordingly, the invention advantageously saves the expense of the cleaning contaminated radiopharmaceutical pigs. While a particular form of the invention has been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. Thus, although the invention has been described in detail with reference only to the preferred embodiments, those having ordinary skill in the art will appreciate that various modifications can be made without departing from the invention. Likewise, it should be appreciated that the scope of the invention includes methods related to the above disclosure. Accordingly, the invention is not intended to be limited, and is defined with reference to the claims ultimately issued in a patent, and the equivalents thereof.
	summary
	abstract	The geometric dimensions and shape of a device for removing solid particles from the cooling medium that is circulated in the primary circuit of a nuclear reactor, in particular a boiling water nuclear reactor, are such that the device can be inserted in lieu of a fuel element or fuel assembly into an empty fuel element or assembly position of the reactor core of the nuclear reactor.
	description	This application is a national phase of International Application Number PCT/US2015/049886 filed Sep. 14, 2015 and claims priority of U.S. Provisional Application No. 62/058,287, filed on Oct. 1, 2014. The contents of all of the above-identified applications are hereby incorporated by reference in their entirety and for all purposes. Field Of The Disclosure The present disclosure relates to a radiographic shield with an S-shaped passageway, further incorporating a radiographic shutter mechanism, and a protective jacket for a radiographic device. Description of the Prior Art In the prior art, the need for protection in the field of gamma radiography is well-established and self-evident. Improvements are continually sought which maintain radiographic safety but which are more economical and less cumbersome to use, as well as providing for efficient work procedures. For example, traditional tungsten shields need to be either a machined straight tube design or an S-tube design. The straight tube design can be machined using conventional machining methods but this design requires shielding attached to the front of the source or source assembly. This design limits the types of radiography that can be performed. S-tube designs typically require a casting process which can be expensive and may produce voids within the material which can reduce shielding efficiency Similarly, traditional tungsten shields need to be either a machined “straight tube” design or an “S” tube design. The straight tube design can be machined using conventional machining methods but this design requires shielding attached to the front of the source. This may limit the types of radiography that can be performed. Finally, the prior art includes protective jackets for radiographic devices which uses a metal handle. However, this is less ergonomic than desired, and typically does not include mounting features. The disclosure relates to various devices in the field of protection in gamma radiography. The disclosure relates to interlocking shielding and a source path within a gamma radiography shield, and a protective jacket for a gamma radiography device. Referring now to FIGS. 1A and 1B, one sees a first embodiment of an interlocking shield 10 for gamma radiography. In this embodiment, typically, a single piece of tungsten is machined into first and second halves 12, 14 using wire EDM (electrical discharge machining). First half 12 includes a longitudinally-oriented indentation 15 which receives the longitudinally oriented ridge 13 of second half 14. End 40 of source path 30 (described in greater detail with respect to FIGS. 3 and 4) opens on first half 12. An alternative embodiment is illustrated in FIGS. 2A and 2B. This embodiment has jigsaw puzzle type characteristics in the opposing portions of the outline of the first and second halves 12, 14 with first half 12 including a first protrusion 16 which tightly interlocks into second undercut recess 18 of second half 14. Likewise, second half 14 includes a second protrusion 20 which tightly interlocks into first undercut recess 22 of first half 12. The pattern creates an interlocking feature which limits the assembly to a single degree of freedom for an extremely strong assembly typically without the need for bolting the first and second halves 12, 14 to each other. This pattern also improves the radioactive shielding by allowing the use of offset overlapping joints which reduces the direct path of the gamma radiation. By the use of separate first and second halves 12, 14, the source path 30 can be machined into each half. This allows for unique source path shapes to be created typically without the need to cast the tungsten. The ability to remove and disassemble the shield allows for inspection and maintenance. This design thereby takes advantage of the radiological shielding properties of machined tungsten while allowing maximum joint design, secure interlocking and provides the ability to machine unique source paths within the shield 10. FIGS. 3 and 4 relate to a shield 10 with a radiological shutter mechanism 42. FIG. 3 illustrates a shield 10 (such as illustrated in FIGS. 1A and 1B), typically made of tungsten, including an S-shaped passageway forming source path 30. It is noted that due to the upward rise 36 in S-shaped passageway or source path 30, that there is no direct or straight open path (i.e., line of sight) between the first end 38 and the second end 40 of source path 30, thereby providing radiological shielding between the first and second ends 38, 40, particularly in view of the preferred tungsten composition of shield 10. FIG. 4 illustrates a radiological device 100 (engaged by a protective jacket 200 as illustrated in FIGS. 6-9), including the modified S-tube source path 30 in combination with a radiological shutter mechanism 42, typically made from tungsten, travelling vertically (in the illustrated orientation) through shaft 43 formed in source path 28. The shutter mechanism 42 is typically manually operated by screw 44 extending through the bottom surface of the shield 10 through passageway 41. The “lazy-S” source path 30 provides shielding adequate when the projector front plate or collimator assembly is attached. The shutter mechanism 42 is typically operated to provide shielding of radiological source 400 during a mode change (for example, from a projector front plate to a collimator assembly) of the gamma radiography device 100. Typically, the primary purpose of the radiological shutter mechanism 42 is to reduce gamma radiation scatter from leaving the source path 30 when the radiographer is changing the device from SCAR (small contained area radiography) mode to projector mode. The S-shaped design, including the upward rise 36 in passageway 30, is intended to provide sufficient shielding to prevent a direct path of radiation from leaving the source path 30, such as from radiological source 400, through second end 40 of source path 30, as illustrated in FIG. 4. This in combination with the shutter mechanism 42 (during the mode change) provides an approach to shield design. The shutter mechanism 42 is used typically to provide shielding only during the mode change. This embodiment exploits the benefits of the shielding of the SCAR assembly and the projector front plate assembly. FIGS. 5-9 relate to an embodiment of a protective jacket 200 for a gamma radiography device 100 (the protective jacket 200 is likewise illustrated in FIG. 4). FIGS. 6 and 7 relate to a polymer molded jacket 200 that is used as a protective cover as well as a device for carrying the radiography device 100. The protective jacket 200 includes handle 202 including interior oriented molded finger indentations 204. First and second ring configurations 206, 208 form a cylindrical space 210 for engaging a radiological device 100. A lower floor 212, which may be partially cylindrical) joins first and second ring Configurations 206, 208 and an open space 214 is formed between the upper portions of first and second ring configurations 206, 208 in order to provide access to the controls of radiological device 100. Further, the end of first ring configuration 206 includes an opening 216 through which radiological device 100 passes to be engaged or disengaged by the protective jacket 200. Second ring configuration 208 includes a closed end wall 218 to secure the radiological device 100. As shown in FIGS. 7-9, the illustrated protective jacket 200 further allows for mounting features when operating the radiological device 100 as a SCAR unit. By using a molded polymer-based protective jacket 200 rather than the industry standard of a simple metal handle, the illustrated embodiment of the protective jacket 200 allows for integrated SCAR mounting features such as mounting apertures 220 on a side of lower floor 212 (see FIG. 8) for a ratchet snap configuration 300 or other fixture kits, FIG. 7 further illustrates a SCAR mounting fixture 400 which includes a first side which is attached to the bottom of the lower floor 212 of protective jacket 200 via the. mounting apertures 220 (see FIG. 9) on the bottom of the protective jacket 200, The SCAR mounting fixture 400 further includes a second side for engaging against the curved surface of the pole 500 (which may be an architectural fixture) or similar structure. This protective jacket 200 further provides a more ergonomic product as compared to prior art protective jackets. Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby.
052176789	claims	1. A gang control-rod controlling system for operating a plurality of control rods at the same time to attain a predetermined control rod pattern, wherein said system comprises: (a) first means storing a first sequence of control rod operations for operating a plurality of control rods at the same time to configure a first control rod pattern, a second sequence of control rod operations for operating a plurality of control rods at the same time to configure a second control rod pattern, and a third sequence of control rod operations for operating a plurality of control rods at the same time to exchange a control rod pattern between said first control rod pattern and said second control rod pattern; and (b) second means for selecting one of said first to third sequences of control rod operations stored in said first means, and operating a plurality of control rods at the same time based on the selected sequence of control rod operations. (a) a first step of previously storing a first sequence of control rod operations for operating a plurality of control rods at the same time to configure a first control rod pattern, a second sequence of control rod operations for operating a plurality of control rods at the same time to configure a second control rod pattern, and a third sequence of control rod operations for operating a plurality of control rods at the same time to exchange a control rod pattern between said first control rod pattern and said second control rod pattern; and (b) a second step of selecting one of said first to third sequences of control rod operations stored in said first step, and operating a plurality of control rods at the same time based on the selected sequence of control rod operations. 2. A gang control-rod controlling system according to claim 1, wherein said second means includes means for inhibiting selection of said third sequence of control rod operations when reactor power is below a set value. 3. A gang control-rod controlling system according to claim 1, wherein said second means includes rod worth limiting means that functions when reactor power is below a set value whereby withdrawal of control rods is inhibited when reactivity worth of those control rods exceeds a predetermined range. 4. A gang control-rod controlling system according to claim 3, wherein said second means further includes means actuatable by an operator for selecting the group number of plural control rods to be operated at the same time, and when said reactor power is below the set value, said rod worth limiting means determines whether or not said control rod group number selected by the operator is in match with said selected sequence of control rod operations and, if the decision is no, inhibits output of said selected sequence of control rod operations. 5. A gang control-rod controlling system according to claim 1, wherein said second means includes first operating means actuatable by an operator for selecting one of said first to third sequences of control rod operations, second operating means actuatable by the operator for selecting the group number of plural control rods to be operated at the same time, third operating means actuatable by the operator for selecting insertion or withdrawal of plural control rods to be operated at the same time, sequence select means for selecting one of said first to third sequences of control rod operations stored in said first means that corresponds to the sequence of control rod operations selected by said first operating means, gang, control-rod select means for selecting position data, associated with control rods of the group number selected by said second operating means, from the sequence of control rod operations selected by said sequence select means, and control rod operation select means for determining, based on the selection by said third operating means, insertion or withdrawal of the plural control rods associated with the position data selected by said gang controlrod select means. 6. A gang control-rod controlling system according to claim 5, wherein said second means further includes means for, when said reactor power is below the set value, determining whether or not the control rod group number selected by said second operating means is in match with the sequence of control rod operations selected by said sequence select means and, if the decision is no, disabling said selected sequence of control rod operations. 7. A gang control-rod controlling system according to claim 1, wherein said first sequence of control rod operations includes first sequence data to configure a first type control rod pattern in which control rods inserted at a rated power comprise only those control rods arranged in the form of a checker board including a control rod at the core center, said second sequence of control rod operations includes second sequence data to configure a second type control rod pattern in which control rods inserted at the rated power comprise only those control rods arranged in the form of a checker board in which a control rod at the core center is not included, and said third sequence of control rod operations includes third sequence data in combination of a part of said first sequence data and a part of said second sequence data. 8. A gang control-rod controlling system according to claim 1, wherein each of said first to third sequences of control rod operations includes data comprising the group numbers of plural control rods to be operated at the same time in correspondence to coordinate values indicative of respective radial positions of the control rods belonging to each group number. 9. A gang control-rod controlling system according to claim 1, wherein said first sequence of control rod operations contains sequence data in which all control rods are divided into first to m-th groups in order of withdrawing the control rods, in the first to fourth groups including those control rods of about half the number of total control rods that are arranged in the form of a checker board and in which a control rod at the core center is not included, and the fifth to m-th groups including the remaining about half control rods; said second sequence of control rod operations contains sequence data in which all control rods are divided into first to n-th groups in order of withdrawing the control rods, the first to fourth groups including those control rods of about half the number of total control rods that are arranged in the form of a checker board including the control rod at the core center, and the fifth to n-th groups including the remaining about half control rods; and said third sequence of control rod operations contains sequence data in combination of the fifth to m-th groups in said first sequence of control rod operations and the fifth to n-th groups in said second sequence of control rod operations. 10. A reactor operation method for operating a plurality of control rods at the same time to attain a predetermined control rod pattern, wherein said method comprises: 11. A reactor operation method according to claim 10, wherein said second step selects one of said second and third sequences of control rod operations when reactor power is below a set value, and selects one of said first, second and third sequences of control rod operations when said reactor power is above the set value. 12. A reactor operation method according to claim 10, wherein said second step selects the group number of plural control rods to be operated at the same time in response to actuation by an operator, outputs said selected sequence of control rod operations only when said control rod group number selected by the operator is in match with said selected sequence of control rod operations when said reactor power is below the set value, and always outputs said selected sequence of control rod operations when said reactor power is above the set value.
	summary
	claims	1. A method of forming a magnetic field of field reverse topology comprising the steps of injecting a plasma into a chamber, applying a magnetic field to form a first magnetic field in the chamber having unidirectional field lines, injecting ion beams into the chamber substantially transverse to the first magnetic field, trapping the ion beams in betatron orbits within the first magnetic field, forming a rotating plasma beam within the chamber having a current and an internal magnetic field due to the first magnetic field, forming a poloidal second magnetic field about the rotating plasma having external field lines outside the rotating plasma extending in a same direction as the field lines of the first magnetic field and internal field lines extending in an opposite direction to the field lines of the first magnetic field, injecting a current through a betatron flux coil in the chamber, inducing an azimuthal electric field inside the chamber, increasing the rotating plasma beam""s rotational velocity, increasing the second magnetic field""s magnitude beyond the magnitude of the first magnetic field, and reversing the direction of the internal field within the rotating plasma and forming a combined magnetic field of field reverse topology (FRC). 2. The method of claim 1 wherein the ion beams are injected substantially transverse to the first magnetic field. claim 1 3. The method of claim 2 further comprising the step of neutrilizing the ion beams. claim 2 4. The method of claim 3 further comprising the step of exerting a Lorentz force due to the first magnetic field on the neutralized ion beams to bend the ion beams into betatron orbits. claim 3 5. The method of claim 4 further comprising the step of draining the neutralized ion beams"" electric polarization. claim 4 6. The method of claim 1 further comprising the step of maintaining the rotating beam plasma at a predetermined radial size. claim 1 7. The method of claim 6 further comprising the step of increasing the first magnetic field""s magnitude. claim 6 8. The method of claim 1 further comprising the step of accelerating the rotating plasma beam to a fusion relevant rotational energy. claim 1 9. The method of claim 8 further comprising the steps of injecting high energy ion beams into the FRC and trapping the beams in betatron orbits within the FRC. claim 8 10. A method of forming a field reversed configuration magnetic field within a reactor chamber comprising the steps of applying a magnetic field to a reactor chamber in which plasma is filled, injecting ion beams into the applied magnetic field within the reactor chamber, forming a rotating plasma beam within the chamber having a poloidal magnetic self-field, and increasing the rotating plasma beam""s rotational velocity to increase the magnetic self-field""s magnitude beyond the applied magnetic field""s magnitude causing field reversal internal to the rotating plasma beam and formation of a combined magnetic field having a field reverse configuration (FRC). 11. The method of claim 10 wherein the step of applying a magnetic field includes energizing a plurality of field coils extending about the chamber. claim 10 12. The method of claim 10 wherein the ion beams are injected substantially transverse to the applied magnetic field. claim 10 13. The method of claim 12 wherein the step of injecting the ion beams further comprises the steps of claim 12 neutrilizing the ion beams, draining the neutralized ion beams"" electric polarization, and exerting a Lorentz force due to the first magnetic field on the neutralized ion beams to bend the ion beams into betatron orbits. 14. The method of claim 10 further comprising the step of increasing the applied magnetic field""s magnitude to maintain the rotating beam plasma at a predetermined radial size. claim 10 15. The method of claim 10 wherein step of increasing the rotating plasma beam""s rotational velocity includes the step of energizing a betatron flux coil within the chamber inducing an azimuthal electric field within the chamber. claim 10 16. The method of claim 15 further comprising the step increasing the current through the flux coil to accelerate the rotating plasma beam to a fusion relevant rotational energy. claim 15 17. The method of claim 16 further comprising the steps of injecting high energy ion beams into the FRC and trapping the beams in betatron orbits within the FRC. claim 16
049967010	claims	1. Method for slit radiography using an X-ray source and a slit diaphragm placed in front of the X-ray source to form a fan-shaped X-ray radiation beam for scanning a body to be investigated to form an X-ray shadow image on an X-ray detector placed behind the body, which fan-shaped X-ray radiation beam is formed by number of sectors situated next to each other, and in which transmitted X-ray radiation is controlled instantaneously for each sector during the scanning movement by means of controllable beam sector attenuators acting in conjunction with the slit diaphragm, characterized by cyclically modulating said X-ray radiation beam in a predetermined manner for all the sectors simultaneously and individually controlling said controllable beam sector attenuators to control cyclically X-ray beam radiation in each sector in synchronization with the predetermined cyclic modulation of X-ray radiation beam. 2. Method according to claim 1, characterized in that the cyclic control is effected by varying the position of the beam sector attenuators with a fixed cycle between a first position essentially transmitting the X-ray beam and a second variable position. 3. Method according to claim 1, characterized in that the cyclic control is effected by varying the position of the beam sector attenuators between a first position essentially transmitting the X-ray beam and a second position controlling the X-ray beam in a maximum manner, a phase of occurrence of the second position being varied with respect to a common predetermined cyclic modulation. 4. Method according to claim 3, characterized in that a starting point of time of the first position is varied. 5. Method according to claim 3, characterized in that an end point of time of the first position is varied. 6. Method according to claim 3, characterized in that duration of the first position is varied. 7. Method according to claim 1, characterized in that cyclic control is effected by vibrating at varied phase said beam sector attenuators 8. Method according to claim 1, characterized in that cyclic control is effected by vibrations at varied amplitude said beam sector attenuators. 9. Method according to claim 1, characterized in that cyclic control is effected at varied phase and amplitude said beam sector attenuators. 10. Method according to one of the preceding claims, characterized in that for each sector signals are generated which are representative of the transmission of the body to be investigated and in that each controllable beam sector attenuators is controlled in accordance with the associated signal. 11. Method according to claim 7 characterized in that a faster second vibration is superimposed on an initial vibration. 12. Method according to claim 8 characterized in that a faster second vibration is superimposed on an initial vibration. 13. Method according to claim 9 characterized in that a faster second vibration is superimposed on an initial vibration. 14. A device for slit radiography comprising an X-ray source, a slit diaphragm placed in front of the X-ray source which forms a fan-shaped X-ray beam with which a body to be investigated can be scanned at least partially to form an X-ray shadow image of the scanned part of the body on an X-ray detector placed behing the body, a control signal generator which, during operation, provides a signal representing the transmission of the body for each sector of the X-ray beam to control means, controllable beam sector attenuators which act in conjunction with the slit diaphragm and which, under the control of the signals from the control means, are able to control the X-ray beam for each sector, characterized by means for providing an X-ray beam modulation for all sectors simultaneously and in a predetermined cyclic manner, said beam sector attenuators being controlled individually in synchronism with cyclic modulation of X-ray radiation. 15. A device according to claim 14, characterized in that the control means control the beam sector attenuators in a manner such that the beam sector attenuators are each brough to an open position, in which the X-ray radiation is able to pass the beam sector attenuators, during at least a part of a first time interval in a rhythm synchronized with the modulation of the X-ray beam, and can be brought to a closed position, in which the beam sector attenuators control the X-ray beam in a maximum manner, during at least a part of a second time interval situated between two first time intervals, and in that the control means are constructed to receive input signals from a radiation detector, which input signals represent quantity of radiation transmitted by the body during at least one measurement interval coinciding at least partially in each case with a first time interval, and if the quantity of radiation in a sector measured during a measurement interval is less than a predetermined value, the control means deliver a control signal which has the effect that the beam sector attenuator associated with said sector is not brought to the closed position during a second time interval following the measurement interval. 16. A device according to claim 15, characterized in that the control means delivers, if the quantity of radiation transmitted by the body during a measurement interval in a sector is less than the predetermined value, a signal which keeps the beam sector attenuator associated with said sector in open position during a subsequent second time interval. 17. A device according to claim 16, characterized in that the control means delivers, if the quantity of radiation measured during a measurement interval in a sector is between two predetermined values, a control signal which brings the beam sector attenuator associated with said sector to a predetermined intermediate position situated between open and closed position. 18. According to claim 14, characterized in that the control means control the beam sector attenuators in a manner such that the beam sector attenuators are each brough to the open position, in which the X-ray beam is able to pass the beam sector attenuators, in a rhythm synchronized with the modulation of the X-ray beam during at least a part of first time interval, and are brought to closed position in which the beam sector attenuators control the X-ray beam in a maximum manner during at least a part of the second time interval which are each situated between two first time intervals, and in that control means receive input signals from the radiation detector, which input signals represent the quantity of radiation transmitted by the body during a measurement interval coinciding each case at least partially with a first time interval, the control means delivering control signals which correspond to the input signals and which control the phase of a subsequent open position interval with respect to cyclic modulation. 19. A device according to claim 18, characterized in that the control signals control length of a subsequent open position interval. 20. A device according to claim 14, characterized in that the modulation means modulates amplitude of supply voltage of the X-ray tube of the X-ray source. 21. A device according to claim 14, characterized in that the modulation means modulates amplidude of current flowing through the X-ray tube of the X-ray source. 22. A device according to claim 14, characterized in that the modulation means comprises at least one element which attenuates X-ray radiation and which cyclically covers or exposes the slit of the slit diaphragm. 23. A device according to claim 22, characterized in that the modulation means comprises a plate-type element extending essentially parallel to a longitudinal direction of the slit of the slit diaphragm over the full length of the slit and at least partially cyclically into a position covering the slit. 24. A device according to claim 22, characterized in that the plate-type element is mounted in a pivotable manner with respect to a spindle situated outside the X-ray beam and extending essentially parallel to said longitudinal direction of the slit. 25. A device according to claim 23, characterized in that the plate-type element is manufactured from piezoelectric material and can swivel into the X-ray beam under the influence of electrical signals with respect to a longitudinal edge, mounted in a fixed manner by means of the other longitudinal edge. 26. A device according to claim 22, characterized in that the modulation means comprise a roller which can be rotated about a spindle extending essentially parallel to the longitudinal direction of the slit, said roller being provided with a number of radial blades of material which attenuates X-ray radiation and extend over a full length of the slit. 27. According to claim 26, characterized in that the radial blades are manufactured of materials which influence X-ray radiation in different manners. 28. A device according to claim 22, characterized in that the modulation means comprise a segmented wheel rotated about a spindle extending transversely with respect to a plane containing the slit of the slit diaphragm located laterally next to the slit said segmented while having a radius at least as large as the length of the slit and having at least one segment manufactured from material attenuating X-ray radiation. 29. A device according to claim 28, characterized in that the segmented wheel comprises a hub provided with a number of radial arms of material attenuating X-ray radiation. 30. A device according to claim 28, characterized in that the segmented wheel comprises first and second segments which alternate with each other and which are manufactured from a first or second material influencing X-ray radiation in different manners. 31. A device according to claim 29, characterized in that the first material transmits soft X-ray radiation and in that the second material transmits essentially hard X-ray radiation. 32. A device according to claim 30, characterized in that said first and second segments are manufactured from lead and copper, respectively. 33. A device according to claim 30, characterized in that said first and second segments are manufactured from aluminum and copper, respectively. 34. A device according to claim 30, characterized in that said first and second segments are manufactured alternately from lead and aluminum, respectively. 35. A device according to claim 14, characterized in that the controllable beam sector attenuators comprise a blade disc, each blade disc comprising at least one blade of material attenuating X-ray radiation, said blade discs being mounted next to each other on a rotable spindle extending essentially parallel to a longitudinal direction of the slit of the slit diaphragm, said blade discs being variably positionable with respect to said rotatable spindle. 36. A device according to claim 35, characterized in that each blade disc is mounted in a slipping manner on the spindle. 37. A device according to claim 35, characterized in that each blade disc is mounted in a sprung manner on the spindle. 38. A device according to claim 35, characterized in that each blade disc is provided with a brake element energized by the control means and by means of which the position of the associated blade disc can be changed with respect to the spindle. 39. A device according to claim 38, characterized in that the blade discs have a circumferential face with which a brake block. 40. A device according to claim 38, characterized in that the brake element is an eddy-current brake.
054085080	abstract	A system for simultaneously testing at least two any control rod clusters contained within a reactor vessel, the system comprising a control rod drive mechanism attached to the control rod clusters for retracting the control rod clusters within said reactor vessel to a position suitable for testing. Electrical power means connected to the control rod drive mechanism for supplying electrical power to the control rod drive mechanism and for terminating the power to the control rod drive mechanism and, when terminated, causing said all said control rod clusters to fall into the reactor vessel. A rod position indicator attached to the control rod drive mechanism for monitoring the position of the control rod clusters; and computing means operatively connected to the rod position indicator and receiving a signal representing the fall time of each control rod cluster for generating an elapsed time profile of all the control rod clusters.
	abstract	A transfer system for spent fuel canisters includes a carrier, a shielded bell trolley movable along the carrier and carrying a shielded bell, and a canister trolley movable along the carrier and carrying a lifting mechanism for raising and lowering the spent fuel canister into and out of the shielded bell. The canister trolley can move along the carrier independent of the shielded bell trolley and the shielded bell trolley can move along the carrier independent of the canister trolley. The shielded bell trolley and the canister trolley can be selectively interlocked for selected transfer operations.
	summary
	claims	1. An extended lifetime system for generating neutrons comprising:an external enclosure;an insulating fluid contained within the external enclosure;a high voltage power supply;a target at a target location supporting a layer of target material capable of being loaded with hydrogen isotopes selected from the group consisting of: deuterium and tritium;an ion source assembly configured to supply a beam of ions, the ion source assembly comprising:a vessel comprising a wall made from an insulator material and having a plasma source cavity containing a plasma source from which a plasma is generated;an anode electrode, connected to the high voltage power supply, the anode electrode being configured to bias the plasma;an external applicator that is:electrically connected to an excitation signal source, andconfigured to deposit electromagnetic energy into the plasma source cavity through electromagnetic fields passing through the wall made from an insulator material,wherein the external applicator is selected from the group consisting of an RF antenna and a microwave launcher,wherein an insulating gap comprising the insulating fluid separates the external applicator and the plasma source cavity; anda target electrode electrically coupled to the targetwherein the high volt a power supply is configured to maintain a voltage between the anode electrode and the target electrode between 10 kV and 500 kV. 2. The system according to claim 1,wherein the target electrode is grounded. 3. The system according to claim 1, wherein the target electrode is connected to a negative voltage supply. 4. The system according to claim 1, further comprising a gas-filling port, a sealing mechanism, and a gas reservoir containing hydrogen isotopes. 5. The system according to claim 1, further comprising a plurality of sensors and diagnostic instruments selected from the group consisting of: a charged-particle detector, a neutron detector, a photon detector, a beam sensor, a current detector, a voltage detector, a resistivity monitor, a temperature sensor, a pressure gauge and a sputtering meter. 6. The system according to claim 1, wherein one or more surfaces of the plasma source cavity are treated to reduce surface recombination properties with respect to atomic hydrogen by one or more of chemical etching, material deposition, baking, coating, and plasma treatment. 7. The system according to claim 1, further comprising a magnetic field producing structure, the magnetic field producing structure having at least one magnet configured to produce a magnetic field having a peak magnetic induction between 0.001 to 1 Tesla near one or more ion beam extraction locations. 8. The system according to claim 7, wherein the magnetic field is shaped to have one or more magnetic mirror surfaces. 9. The system according to claim 7, wherein the external applicator is adjusted relative to the magnetic field to achieve resonance near one or more ion beam extraction locations, wherein the resonance is taken from the group consisting of:electron cyclotron resonance, andelectron mirroring bounce frequency resonance. 10. The system according to claim 1, wherein the external applicator and the plasma source cavity are configured to produce a plasma having a majority of monatomic ions near at least one extraction orifice. 11. The system according to claim 1, wherein the external applicator and the plasma source cavity are configured to produce a plasma with an efficiency between 6.5 microamps and 10 microamps extractable ion current per Watt of electromagnetic power. 12. The system according to claim 1, wherein the target material is loaded with deuterium. 13. The system according to claim 1, further comprising one or more suppression electrodes connected to a voltage supply configured to bias the suppression electrode between 0 and −10 kV relative to the target electrode. 14. The system according to claim 1, wherein the external applicator is configured to supply electromagnetic energy having a frequency of between 0.1 MHz and 20 GHz to the plasma source cavity. 15. The system according to claim 1, wherein the target electrode is thermally-connected to one or more of a thermal management system and a vacuum vessel that encloses the plasma source cavity. 16. The system according to claim 1, wherein the target electrode is one or more of thermally-connected to the external enclosure and electrically-connected to the external enclosure. 17. The system according to claim 1, wherein the plasma source cavity includes two or more extraction orificeswherein the anode electrode comprises two or more extraction electrodes, each of which is configured to extract a separate ion beam from the plasma source cavity through one of the two or more extraction orifices and direct the extracted ion beam at a separate target; andwherein the positive voltage supply is connected to a single power supply. 18. A method for generating neutrons using a neutron generator comprisingan external enclosure;an insulating fluid contained within the external enclosure;a high voltage power supply;a target at a target location supporting a layer of target material capable of being loaded with hydrogen isotopes selected from the group consisting of; deuterium and tritium;an ion source assembly configured to supply a beam of ions, the ion source assembly comprising:a vessel comprising a wall made from an insulator material and having a plasma source cavity containing a plasma source from which a plasma is generated;an anode electrode, connected to the high voltage power supply, the anode electrode being configured to bias the plasma;an external applicator that is:electrically connected to an excitation signal source, andconfigured to deposit electromagnetic energy into the plasma source cavity through electromagnetic fields passing through the wall made from an insulator material,wherein the external applicator is selected from the group consisting of an RF antenna and a microwave launcher,wherein an insulating gap comprising the insulating fluid separates the external applicator and the plasma source cavity; anda target electrode electrically coupled to the targetwherein the high voltage power supply is configured to maintain a voltage between the anode electrode and the target electrode between 10 kV and 500 kV,the method comprising:feeding an excitation signal to the external applicator;coupling, through electromagnetic fields, electromagnetic energy produced by the external applicator into a gas within the plasma source cavity;extracting, from the plasma source cavity, an ion beam, andcausing the ions in the ion beam to collide with target material in the target material layer to generate neutrons. 19. The method according to claim 18, further comprising one or more of the group consisting of:applying an extraction electrode or electrostatic field shaping element to improve beam quality such that a substantial fraction of ions exiting the ion source are on trajectories to impinge on the target;substantially occluding metallic electrodes from contacting the plasma contained within the ion source to reduce sputtering and erosion;operating a plasma source at or near a resonance condition to generate a majority fraction of monatomic ions that improve the effective energy per ion accelerated to a target location,wherein the plasma ion source is generated in a cavity having one or more reduced atomic-recombination surfaces resulting from material selection and surface treatment and one or more constrictions that decrease the flow of neutral atomic species out of the ion source. 20. The system according to claim 1 wherein in operation the external applicator is maintained near ground electric potential. 21. The system according to claim 1, wherein the target material comprises lithium.
	abstract	A control rod assembly including at least one movable control rod including a neutron absorbing material, a control rod drive mechanism (CRDM) for controlling movement of the at least one control rod, and a coupling operatively connecting the at least one control rod and the CRDM. The coupling includes a terminal element engaged with a connecting rod of the CRDM and the at least one moveable control rod, and a kinetic energy absorbing element supported by the terminal element for absorbing kinetic energy during a SCRAM event, the kinetic energy absorbing element configured to act between the terminal element and an upper plate of an associated fuel assembly.
052572986	abstract	This invention provides nuclear fuel pellets including fission substance of UO.sub.2 or UO.sub.2 having Gd.sub.2 O.sub.3 added thereto, the pellets comprising a satisfactory solid-solution state (homogeneous state), large grain diameters, and a second precipitation phase deposited in grain boundaries, and still having a sufficiently high density. This invention also provides a method of manufacturing the above-described nuclear fuel pellets.. The nuclear fuel pellets of this invention comprise UO.sub.2 or (U, Gd) O.sub.2 grains and an aluminosilicate precipitation phase, the precipitation phase being a glass state or a crystalline state, the grains having an average grain diameter of about 20 .mu.m through about 60 .mu.m, the aluminosilicate precipitation phase having a composition including SiO.sub.2 of about 40 wt % through about 80 wt % and Al.sub.2 O.sub.3 of the residual on average, the amount of the alumina and silica being about 10 ppm through about 500 ppm with respect to the total amount of the nuclear fuel pellets, the pellets having porosity of 5 vol % at a maximum.
055704689	claims	1. A method of decontaminating substances contaminated with radioactivity, comprising the steps of: decontaminating a substance contaminated with radioactivity by using a chelate liquid, removing the chelate liquid from the contaminated substance, drying and heating the contaminated substance by hot air at a temperature not lower than the boiling point of a solvent, adding said solvent to the contaminated substance to rapidly vaporize the solvent so as to separate any remaining chelate liquid, which has been adhering to the contaminated substance, from the contaminated substance, and removing the thus separated chelate liquid from the contaminated substance along with said solvent. 2. A method of decontaminating substances contaminated with radioactivity according to claim 1, wherein said solvent is methylene chloride. 3. A method of decontaminating substances contaminated with radioactivity according to claim 1 or 2, wherein said substance contaminated with radioactivity is shot blasting grit.
048470384	description	DETAILED DESCRIPTION FIG. 1 shows a primary circuit loop of a pressurized water nuclear reactor comprising a steam generator 1, a primary pump 2 and primary pipes 3 and 4 enabling the reactor vessel 6 to be connected to the steam generator and to the primary pump, respectively, as well as a pipe 5 enabling the steam generator 1 to be connected to the primary pump 2. The primary pipes 3 and 5 are connected to the lower part 1a of the steam generator, which forms a water box. Pressurized water for cooling the reactor is circulated through the loop by the primary pump 2. The water heated in contact with the core arranged in the reactor vessel 6 enters the water box 1a of the steam generator through the primary pipe 3 known as the hot leg. The water then travels through the steam generator tubes, where it cools while heating and vaporizing the feed water. The cooled water then returns to the outlet part of the water box 1a and is then conveyed to the reactor vessel via the pipes 5 and 4, the pipe 4 forming the cold leg. The pipe 5, which provides the connection between the steam generator 1 and the primary pump 2, is U-shaped and, because of this, is referred to by the name of U leg. The steam generator 1 and the primary pump 2 are placed with their axes vertical and rest on articulated prop assemblies 8 and 9, respectively. FIG. 2 shows a part of the reactor building 10 which contains the vessel 6 and the whole primary circuit of the reactor. The part of the reactor building 10 shown in FIG. 2 shows a compartment 11 or bunker intended to receive a steam generator 1. The steam generator rests on the floor 12 of the bunker 11 by means of the articulated props 8. The centering and the positioning of the steam generator 1 in the bunker 11 are provided at the rings 13 and 14, the ring 13 consisting of 6 lateral abutments 17 attached to three of the bunker walls. The casing of the steam generator 1 is connected by its top part to a steam outlet pipe 15. As can be seen in FIGS. 2 and 3, in line with each of the props of the supporting assembly 8, the steam generator 1 has an abutment sliding plate 16 intended to provide the steam generator 1 with horizontal support, in association with an abutment 17 fastened to the bunker wall 11. Bearing devices 18 consisting of dampers are anchored in an intermediate floor of the bunker 11, at the upper ring 14. These dampers 18 come to bear on the ring 14 and, like the assemblies 16 and 17, provide the horizontal support and the retention of the steam generator in its bunker. Both the horizontal support devices and the props 8 allow the steam generator a certain play inside its bunker, a certain displacement of the steam generator body being possible, within the permissible limits, during its operation. The steam generator 1 shown in FIGS. 1, 2 and 3 is a worn-out steam generator whose tube bundle, arranged inside the body, has suffered a degree of deterioration in service, with the result that it is intended to carry out a complete replacement of this steam generator. To this end, a new replacement steam generator which is to be substituted for the steam generator 1 has been manufactured in the workshop. This new replacement steam generator 20 is shown in FIG. 4 in a horizontal position on supporting devices 21. The lower part 20a of the generator 2, forming the water box, comprises two pipeworks 22a and 22b intended to be connected to the primary pipes 3 and 5 of the loop shown in FIGS. 1, 2 and 3, after the removal of the worn-out steam generator 1. The bottom 20a of the steam generator is also pierced with openings 23a and 23b forming entry openings or manholes making it possible to gain access to the interior part of the water box. The outer wall of the lower part 20a of the steam generator has projecting parts 25 forming feet for supporting the steam generator. Before the replacement of a worn-out steam generator with a new generator such as the generator 20 is carried out, certain topometric measurements are carried out in the workshop, as shown in FIG. 4. The steam generator 20 is arranged with its axis 24 in a substantially horizontal position and a topometric measurement instrumentation 26 is arranged in the vicinity of the lower part 20a of the steam generator, to perform highly accurate measurements. The topometric measurement instrumentation of a conventional type comprises sighting telescopes 27 and a measurement processing, recording and display unit 28. The topometric measurements which are carried out relate to the position and the direction of the steam generator axis 24 and, as shown by the arrows 30 and 31, to the position and the direction of the pipework 22a, 22b and the bearing faces of the feet 25. Topometric measurements are also performed on other parts of the steam generator, to determine the exact position of the bearing regions of the upper ring and of the pipework for connection to the steam line 15. Other topometric measurements are performed on the worn-out steam generator, inside the bunker 11 in which this steam generator is placed. The topometric measurements which are carried out by employing an instrumentation of the type of that shown in FIG. 4 permit an accurate determination of the position of the pipework connecting the primary pipes to the worn-out steam generator and the position of the horizontal and vertical bearing and supporting surfaces. The topometric measurements are recorded and compared with the topometric measurements performed on the new replacement steam generator. This comparison permits a preliminary determination of the procedure for replacing the steam generator, i.e., the number and the position of the sectioning operations to be carried out on the primary pipes and the modifications to be made to the vertical and horizontal support devices. The system of reference axes in which the position of the various members for connecting, supporting and positioning of the steam generator is determined comprises a first horizontal axis OX corresponding to the axis of the hot leg 3 and a second horizontal axis OY, perpendicular to the first, situated in the vertical plane containing the axis of the U leg 5, with both these axes intersecting on the vertical axis of the generator. The third axis OZ of the reference system conincides with the steam generator axis if the latter is perfectly vertical. Reference will now be made to FIGS. 6a, 6b, 7a and 7b to indicate the guiding principles by which the procedure for the replacement of the steam generator is determined. FIG. 6a is a diagrammatic elevation view of the steam generator in the direction at right angles to the axis of the hot leg. FIG. 6b is a view in a direction parallel to the axis of the hot leg. FIGS. 6a, 7a and 7b show several examples of sectioning operations which may be performed on the hot leg 3 and on the U leg 5, to separate the worn-out steam generator 1 from the primary circuit. The guiding principle determining the choice of the sectioning operations consists in effecting the sectioning as close as possible to the corresponding connecting pipework (7a or 7b), while retaining the possibility of subsequently connecting the new steam generator to the ends of the primary pipes left in preparation. The sectioning should also make it possible to discard the ferritic steel region of the primary pipes in the-vicinity of the connecting welds of the worn-out steam generator. FIGS. 6a, 7a and 7b show a section 35 enabling the hot leg to be separated from the corresponding pipework 7a of the steam generator. FIG. 7a also shows the section 36 enabling the second pipework 7b to be separated from the U leg 5. The comparison of the topometric measurements which are carried out beforehand is primarily intended to determine whether two sectioning operations such as 35 and 36 are sufficient to permit the new steam generator to be connected up, given its geometry as determined by topometric measurement, to the ends of the primary pipes 3 and 5 left in preparation after the sectioning operations 35 and 36 have been carried out and the steam generator 1 has been withdrawn from its bunker 11. One of the possibilities is, therefore, the determination of a procedure involving only two sectioning operations 35 and 36. The comparison of the topometric measurements may also reveal the impossibility of carrying out the connection of the new steam generator merely by carrying out the two sectioning operations 35 and 36. In this case, after the generator 1 has been withdrawn from its bunker, two new sectioning operations 38 and 39 must be performed to separate the bends 40 and 41 from the corresponding primary pipes, these bends 40 and 41 being subsequently replaced by two bends of different geometry which are welded to the end of the pipes 3 and 5. These new bends make it possible to adapt to the geometry of the bottom of the replacement steam generator 20. The sectioning operations 35 and 36 and, if appropriate, the sectioning operations 38 and 39 are performed by an orbital sectioning machine placed in position after decontamination of the region to be sectioned. The comparison of the topometric measurements carried out on the new replacement steam generator 20 with the topometric measurements carried out on the worn-out steam generator and on the primary circuit also makes it possible to determine the modifications to be made to the devices for shimming and positioning of the steam generator. These shimming and positioning devices are shown diagrammatically in FIGS. 6a and 6b. These devices principally include vertical adjustment shims 42 which are inserted between the bearing plates 44 fastened to the feet of the steam generator 1 and the bearings (43) forming the top part of the props 8 supporting the steam generator. It can be seen that the adjustment shims 42 may be machined with their faces slightly inclined relative to each other in order to make a correction to the direction of the steam generator axis. The supporting and positioning devices also include adjustment shims 45 inserted between the sliding plates 16 of the steam generator which is fastened onto the bearing plates 44 and the abutments 17 fastened to the walls of the steam generator bunker 11. Lastly, these devices include shims 46 inserted between the ring 14 and the steam generator body 1 and shims 47 inserted between the ring 14 and bearing plates fastened to the walls of the bunker 11. The size and the shape of these shims may be determined in advance from the comparison of the topometric measurements. This determination will need to allow for the operating clearances which are to be left between the steam generator and its bearings. FIG. 5 shows the supporting and bearing connections left in preparation in the steam generator bunker after removal of the worn-out steam generator. Topometric measurements are carried out on these components by virtue of an instrumentation of the same type as that shown in FIG. 4 and comprising sighting telescopes 27 and a measurement processing, recording and display unit 28. These measurements are carried out after the primary pipes have been clamped in the position which they are to occupy after the welding of the new steam generator. The topometric measurements cover the position and the direction of the connection planes of the primary pipes 3 and 5 and of the bearing planes of the vertical support devices 43 and of the horizontal support devices 17. These measured positions and directions are shown in FIG. 5 by means of the arrows 50, 51 and 52. It should be noted that, before carrying out the topometric measurements on the ends of the pipes 3 and 5 to determine the position of the connection planes, a grinding operation is performed on these end faces of the pipes, after their sectioning. The result of the topometric measurements carried out in the bunker 11 after removal of the worn-out steam generator is compared with the result of the topometric measurements carried out on the new replacement steam generator. From this comparison, the exact position of the connection plane between the pipeworks 22a and 22b of the new generator and the end parts of the corresponding pipes 3 and 5 is deduced. This determination is expressed by the plotting of a circular line on the external surface of the pipes 3 and 5. It will be seen later that this plot may be performed or checked by employing a framework reproducing the principal components of the bottom of the steam generator. Comparison of the measurements also makes it possible to determine more accurately than previously the shape to be given the shimming components and to the sliding plates of the steam generator, as a function of the geometry of the new steam generator 20 and of the bearings 17 and 43 left in preparation in the steam generator bunker. FIG. 8 shows the part of the end of a prop 8 comprising a bearing bracket 43 pierced by holes through which pass the assembly bolts 54. The assembly bolts 54 pass through aligned holes in the vertical adjustment shim 42 and in the bearing plate 44 and are screwed into tapped holes provided in the corresponding foot 55 of the steam generator. The sliding plate 16 is bolted to the bearing plate 44 which projects relative to the foot 55. FIG. 9, which shows the prepared components in the steam generator bunker, shows, in plan view, the distribution of the bearing abutments 17 interacting with the sliding plates 16 of the steam generator, for its horizontal support, and the bearing surfaces of the brackets 43 on which the feet 55 of the steam generator come to rest. FIG. 9a shows, in plan view, the sliding plates 16 and the corresponding feet 55 of the steam generator. Comparison of the topometric measurements carried out on the prepared components and on the new steam generator makes it possible to determine the exact shape of the sliding plates 16 and of the associated vertical and horizontal adjustment shims at the foot of the steam generator. Thus, after the stages of the procedure which have been described, means are available for fitting the new replacement steam generator with bearing devices which are adapted to its being fitted into the bunker of the worn-out steam generator. The comparison of the topometric measurements also makes it possible to plot the exact connection planes on the pipes 3 and 5 which have been left in preparation. Before performing the machining of the welding chamfers on the pipes which have been left in preparation, with their end faces representing the connection plane, a check is made nevertheless by employing a mounting framework such as shown in FIGS. 10 and 11. A framework of this kind comprises a welded and bolted structure 60 in the shape of a truncated pyramid whose polygonal base comprises an opening of sufficient size to permit the passage of the lower part 20a of the steam generator. The mounting framework 60 comprises fastening members 61 enabling it to be attached to two fastening rings 62, themselves attached to the outer surface of the steam generator. In a first stage, the mounting framework is placed in position and is fastened by virture of the devices 61, 62 by virtue of lugs 63, to the bottom of the new steam generator 20 which is to replace the worn-out steam generator withdrawn from the bunker 11. When the positioning of the structure of the mounting framework on the bottom of the steam generator is ensured so that the axis of the framework is in perfect coincidence with the steam generator axis 24, there are fastened onto this framework 60 devices 64 and 65 intended to represent physically the position of the sliding plates and of the bearing shims on the framework reproducing the bottom of the steam generator and to plot or to check the circular line representing the connection plane on the primary pipes. In order to perform the plotting or the checking of the connection plane, two devices 65 are employed and these are positioned on the framework in positions corresponding to the pipework 22a and 22b and whose structure is shown in FIGS. 12 and 13. In FIG. 12, the device 65 has been shown at the end of its positioning at a pipework, for example the pipework 22a for connection to the hot leg. This position corresponds to the position of the framework shown in FIGS. 10 and 11, where this framework 60 is placed in position on the lower end of the new steam generator. The device 65 comprises an outer crown ring 66 onto which are welded two members 67 for fastening in radial direction. Axial holes are machined in the outer crown ring 66 and in the fastening components 67. Two trunnions 68 are mounted in the axial holes for rotation around the axis 69. An inner crown ring 70 is mounted for rotation around the axis 69, inside the outer crown ring 66, by virtue of removable axial end-pieces 71. The inner crown ring 70 carries an adjustment ring 72 on which are mounted screw centering and adjusting assemblies 73. Perfect positioning and centering of the device relative to the connection end of the pipework 22a is ensured by means of the devices 73, when the framework is in position on the new steam generator. A clamping stirrup 74 enables the device 65 to be held in its adjustment position while it is being fastened by welding onto the framework 60. When the two devices 65 corresponding to the pipework 22a and 22b of the new steam generator are placed in position and fastened to the framework, the plane at right angles to the axis of the pipework 22a passing through the axis 69 of the device 65 perfectly represents physically the plane of connection of the pipework to the primary pipe left in preparation in the steam generator bunker. When the mounting framework is positioned on the lower part of the steam generator, as shown in FIGS. 10 and 11, the fitting of the centering feet, which are intended to represent physically the position of the feet and of the sliding plates of the steam generator to be installed, is also carried out. A foot 64 of this kind has been shown in FIGS. 14, 15 and 16. The foot 64 comprises an upright 81 intended to ensure its connection to the framework 60 and a plate 82 or false sliding plate whose cross-section in plan view reproduces exactly the shape and the dimensions of a sliding plate of the new steam generator as they are defined by the topometric measurements, thus permitting perfect horizontal shimming of the replacement steam generator in the bunker 11 of the worn-out steam generator. Thus, the shape of these false skidding plates in plan view reproduces substantially the shapes of the skidding plates 16 shown in FIG. 9a. The bearing plate 82 is fixed by its bottom face to a vertical adjustment shim 83 intended to represent physically on the framework the definitive adjustment shim, such as the shim 42 shown in FIG. 8. The plate 82 and the shim 83 are intended to replace, on the framework, the bearing plate 44 and the shim 42, which are shown in FIG. 8. The plate 82 also carries three blocks 84 by means of bolts 85 whose position is adjusted in order to ensure positioning of the foot 64 against the corresponding foot 25 of the new steam generator, whose outline is shown in dotted lines in FIG. 14. Stud sockets 86 are provided throughout the thickness of the plate 82 and the shim 83. When the foot 64 is placed so as to coincide with a foot 25 of the new generator, by virtue of the blocks 84, the holes 86 permit the passage of studs for assembling the foot 64 of the framework with the foot 25 of the new steam generator. With the framework positioned on the new steam generator, as shown in FIGS. 10 and 11, the fitting of the four feet 64 onto the corresponding feet 25 of the steam generator is carried out and then these feet are fastened onto the framework by means of the uprights 81, which are rigidly fastened onto this framework 60. The framework is then ready to be transported to the bunker of the worn-out steam generator, in order to check the position of the connection planes and of the bearing surfaces as determined by topometric measurements. The stirrups 74 of the devices 65 are removed, the assembly studs on the feet of the steam generator are unbolted and the framework is separated from the new steam generator. The centering and positioning devices 73 of the assemblies 65 are removed and the inner crown ring 70, 72 of the devices 65 is pivoted through 180.degree., this inner crown ring 70, 72 being placed and held in its second position, shown in FIG. 13. The mounting framework 60 is brought into the bunker 11 of the worn-out steam generator and is placed in the exact position which is to be occupied by the bottom of the new steam generator 20. In this position, the false sliding plates 82 of the feet 64 lodge in the spaces provided between the abutments 17, and the locations of the steam generator feet 28 are superposed on the bearing surfaces of the brackets 43 of the props 8. The alignment of the stud holes 86 with the holes provided in the brackets 43 and the perfect positioning of the mounting framework 60 representing the lower part of the new steam generator 20 are checked. The devices 65 which physically represent the connection planes are placed on the ends of the primary pipes in the manner shown in FIG. 13. The adjustment ring 72 of each of the devices 65 comprises four bores 75 through which pass scribers enabling a circular line to be scribed on the outer surface of the pipe 3 (or 5), this circular line perfectly representing physically the position of the plane of connection of the corresponding pipework 22a (or 22b) to the pipe. In this manner it is possible either to scribe the line representing physically the end plane of the welding chamfer or to check the position of a line scribed previously, by employing the results of topometric measurements. When the checks have been carried out, a welding chamfer is machined on the end of the pipes 3 and 5, using a chamfering machine of the orbital type, such as shown in FIGS. 17 and 18. A machine of this kind comprises a stationary part 90 which can be centered inside the pipe 3 (or 5) and a part 91 which can move in rotation relative to the part 90, around an axis whose positioning is defined during the centering and the positioning of the part 90 inside the pipe 3 (or 5). The adjustment of the working position of the weld chamfering machine on each of the pipes can advantageously be made by employing the adjusting device described in applicant's French patent application filed simultaneously with the present patent application. In fact, the results of the topometric measurements and/or the plot obtained by virtue of the mounting framework make it possible to determine the position of the chamfer and of its axis corresponding to the machining axis of the machine 90, 91. This axis is generally not the axis of the pipework, both in respect of its direction and its position relative to the machined section. When the chamfer machinery has been carried out on the ends of each of the primary pipes 3 and 5, the new replacement steam generator is positioned in the bunker 11, in the place of the framework, this generator being perfectly located in the vertical support devices and between the horizontal support abutments. Similarly, the pipework connection planes correspond perfectly to the connection planes of the chamfers machined on the primary pipes. The welded connection can then be made, for example by virtue of a TIG orbital welding process, such as described in applicant's French Patent Application No. 87/00,590. Advantageously, after they have been sectioned, the primary pipes are clamped in the positions which they are to occupy after welding. In this positioning by clamping, allowance is made for the shrinkage which accompanies the welding. Thus, the procedure according to the invention permits a complete replacement of a worn-out steam generator by perfectly determining the refitting procedure, the modifications to be made to the supporting devices and the position of the planes of connection of the steam generator to the primary pipes. The invention is not limited to the embodiment which has been described. Thus, the various positioning and shimming members employed can be adapted to the positioning and shimming members of the worn-out steam generator which is being replaced, according to the replacement procedure which is chosen. No precise description has been given of the manner in which the steam generator is connected to components such as the steam discharge pipework. The position of such components is less critical than that of the primary pipes or the lower support or shimming means, and the adapting of their connection does not present a special problem, once the support, the shimming and the connection of the lower part of the steam generator have been completed. The method according to the invention applies to the replacement of any steam generator of a pressurized water nuclear reactor.
050013513	abstract	In an object holder comprising an X-Y translation mechanism, both movements are determined by transporters which are separately moved across a supporting face of a supporting plate under a pressure in a sliding fashion. The pressing force is preferably realized by means of permanent magnets which are mounted on the transporters and which bear on the supporting face of the supporting plate by way of preferably ductile spacers. A device for rotation and/or tilting can be simply added by rotating and/or tilting the entire supporting plate with the X-Y translation mechanism.
050892177	summary	BACKGROUND OF THE INVENTION 1. Field Of The Invention The present invention relates to the field of decontamination of nuclear reactor primary systems. More specifically, it relates to a unique method of removing suspended and dissolved solids from chemical decontamination fluids. 2. Description Of The Prior Art The problem of excessive personnel exposures caused by high background radiation levels in a nuclear reactor primary system, such as in pressurized water reactor (PWR) systems, and the resultant economic cost of requiring personnel rotation to minimize individual exposure is significant at many nuclear plants. These background levels are principally due to the buildup of corrosion products in certain areas of the plant. The buildup of corrosion products exposes workers to high radiation levels during routine maintenance and refueling outages. The long term prognosis is that personnel exposure levels will continue to increase. As a nuclear power plant operates, the surfaces in the core and primary system corrode. Corrosion products, referred to as crud, are activated by transport of the corroded material to the core region by the reactor coolant system (RCS). Subsequent release of the activated crud and redeposition elsewhere in the system produces radiation fields in piping and components throughout the primary system, thus increasing radiation levels throughout the plant. The activity of the corrosion product deposits is predominately due to Cobalt 58 and Cobalt 60. It is estimated that 80-90% of personnel radiation exposure can be attributed to these elements. One way of controlling worker exposure, and of dealing with this problematic situation, is to periodically decontaminate the nuclear steam supply system using chemicals, thereby removing a significant fraction of the corrosion product oxide films. Prior techniques had done very little to decontaminate the primary system as a whole, typically focusing only on the heat exchanger (steam generator) channel heads. Two different chemical processes, referred to as LOMI (developed in England under a joint program by EPRI and the Central Electricity Generating Board) and CAN-DEREM (developed by Atomic Energy of Canada, Ltd.), have been used for small scale decontamination in the past. These processes are multi-step operations, in which various chemicals are injected, recirculated, and then removed by ion-exchange. Although the chemicals are designed to dissolve the corrosion products, some particulates are also generated. One method of chemical decontamination, focusing on the chemistry of decontamination, is disclosed in U.K. Patent Application No. GB 2 085 215 A (Bradbury et al.). There is little disclosure, however, of the methodology to be used in applying that chemistry to system decontamination. While these chemical processes had typically been used on only a localized basis, use of these chemical processes has now been considered by the inventors herein for possible application on a large scale, full system chemical decontamination. Such an application is disclosed generally in co-pending Application Ser. No. 07/62/120 entitled "System For Chemical Decontamination Of Nuclear, Reactor Primary Systems", and incorporated herein by reference. While some work has been done in the boiling water reactor (BWR) programs, the BWR scenarios examined by those in the field involved only decontaminating fuel assemblies in sipping cans employing commercial processes at off-normal decontamination process conditions with little regard for the effects of temperature, pressure, and flow that would be mandated by an actual application of the process to the full reactor system. The estimated collective radiation dose savings over a 10-year period following decontamination is on the order of 3500-4500 man rem, depending upon whether or not the fuel is removed during decontamination. At any reasonable assigning of cost per man-rem, the savings resulting from reduced dose levels will be in the tens of millions of dollars. As a result of the examination of potential full system decontamination, a need now exists for an effective and economic method to remove dissolved and particulated corrosion products generated by the application of the known chemical decontamination techniques from the chemically-injected primary system fluids. SUMMARY OF THE INVENTION The present invention is directed to a clean-up sub-system to be used in conjunction with a chemical decontamination system for full nuclear reactor primary system decontamination. The present invention allows for on-line decontamination. To this end, multiple banks of demineralizers are utilized in parallel. By alternating process flow between the multiple banks of demineralizers, the resin beds can be replaced during system operation. This leads to economies of scale, time, and cost. A back-flushable filter is utilized to remove suspended solids prior to demineralizing of the dissolved solids. Additional filters can be provided prior to, or after, the demineralizing step to further remove suspended solids and resin fines. The present system is designed to operate without significantly extending the time required for the decontamination operation, which is typically on the critical path downtime for a commercial PWR nuclear reactor. Accordingly, it is an object of the present invention to provide a decontamination clean-up sub-system to economically and quickly remove suspended and dissolved solids generated during a chemical decontamination process used on a nuclear reactor primary system. These and further objects and advantages will be apparent to those skilled in the art in connection with the detailed description of the invention that follows.
051475960	description	DETAILED DESCRIPTION OF THE INVENTION Central to the concept of the invention is the generation and control of one straight and at least one toroidal relaxing plasma region within a simply-connected common volume so as to produce a RFP configuration with an inner open-ended poloidal divertor, utilizing a non-zero homotopic invariant. The preferred embodiment described herein uses, where possible, techniques and apparatus that are known in the art of producing and applying hot, magnetically confined plasmas. A preferred embodiment of the invention is illustrated in FIG. 2, such device producing magnetic surfaces as illustrated in FIG. 1. As illustrated in FIGS. 1 and 2, a plasma comprising one toroidal relaxing plasma channel (10) with region of toroidal reversal (12) and one straight relaxing plasma channel (14) is created within a primary vacuum chamber formed by a wall (16) so as to form an open-ended divertor separatrix (18) having poloidal null (20) in the inner side of the toroidal region, with elliptic axis (22) and nested closed magnetic surfaces (24) and (26), and with nested open magnetic surfaces (28) and (30), respectively. In the Figures, flux surfaces where the toroidal magnetic component is negative are dotted. Surrounding magnetic surfaces (32) and (34) at the outerboard of the toroidal pinch are also illustrated in FIGS. 1 and 2. Relaxing plasmas regions (10) and (14) and chamber wall (16) are symmetric with respect to the toroidal major axis (vertical axis of rotational symmetry) (36) and midplane (38). The chamber wall (16) is made of a material having low electrical conductivity and compatible with high vacuum technique as practiced in RFP devices. It should have sufficiently high toroidal resistance so as to permit penetration of induced toroidal electric field in time desired to drive toroidal plasma current. Standard vacuum pumping systems are used for evacuating the chamber to high vacuum. The chamber wall (16) is shaped so as to closely approximate the desired shape of the plasma. The major radius R.sub.0 of the plasma device illustrated is 0.24 m from the major axis (36) to the elliptic axis (22). The chamber is 0.27 m high with 0.35 m radius at its widest midplane point and 0.05 m radius at its extremities. The minimal vertical diameter of the "neck" (39), establishing transition between the open-ended region ("shaft") (10) around the axis (36) and the toroidal region (14), is 0.11 m in the illustrated embodiment, but the exact value of this dimension may be changed as desired or required for improved plasma performance with no change in the nature of the invention. Large necks allow for a more effective helicity pumping from the cylindrical region (14) surrounding the major axis (36) into the toroidal region (10), whereas small necks allow for a more effective close-fitting shell for stabilization. Chamber cross-sectional dimensions may be scaled to be larger or smaller, maintaining proportions close to those given above. The characteristic boundary shape, the purpose of which is to force the relaxation of the straight plasma discharge (14) and toroidal plasma region (10) and the formation of the inner divertor (18), is imparted by a shaped shell (40) and distributed poloidal field windings (42) and (46). Shaped conducting shells have been used for many years to impart particular shapes to plasmas, with the most similar prior art applications being in multipinch toroidal devices, as in Ohkawa's U.S. Pat. No. 4,543,231. The exact shape of the shell (40) is determined by solution of the Grad-Shafranov equation for MHD equilibrium to be described in subsequent paragraphs, in order to yield a plasma with the properties sought. At the same time, the close-fitting shell (40) allows, together with the divertor (18), for benefiting from stabilization by image-currents to surface-modes without detrimental interactions of the plasma with the wall (16). The shaped shell is made of a highly conducting metal. The shell also includes an electrically non-conductive break to prevent the flow of net toroidal current in the shell, which would otherwise act as a short-circuited secondary circuit for induction winding. The purpose of the electrodes (44) is to create an axial electric field to ionize gas within chamber (16), thereby generating plasma, and to drive sufficient current through said plasma to contribute an important part in its resistive heating to high temperature. The axial current also contributes an important part of the toroidal magnetic field in the toroidal region of confinement of the hot plasma, as well as of its poloidal magnetic field, through helicity injection. The basic principles of this technique are nowadays well understood and have been applied in several devices, such as in the sustainment of a spheromak, using a kinked z-pinch as the helicity source (Jarboe T. R., Barnes C. W., Platts D. A. and Wright B. L., in Comments Plasma Phys. Controlled Fusion, 1985, Vol. 9, No. 4, pp. 161-168). Thus, the current driven between the electrodes must be sustained for the desired duration of plasma confinement. For the embodiment illustrated in FIGS. 1 and 2, at steady state, a d.c. voltage of 20 V is to be maintained between the electrodes, in order to sustain the desired toroidal magnetic field, driving a vertical current of 15 kA. Since large currents are required to be driven between the electrodes, they must be made of a material particularly resistant to high heat loads. Special shaping of the electrode may reduce the heat load per surface unit; moreover, in order to allow for a rapid reversal of the axial magnetic flux, according to the preferred method of production described hereunder, the electrodes should be hollow (not illustrated). The electrodes (44) are separated from the wall (16) and from the shell (40) by electrical gaps. The primary purpose of the poloidal field coils ((42) and (46)) is to provide magnetic boundary conditions required for the preservation of the topological variant. Poloidal field coils (46) serve also as vertical field coils in the discharge channel (14) between the electrodes (44) according to a technique standard in "stabilized z-pinch" devices. Both coils ((42) and (46)) may also conveniently serve as induction coils, and supplement the electrodes (44) in heating the plasma. Namely, they may induce sufficient high toroidal current through said plasma to contribute significantly to its resistive heating. In the illustrated embodiment, the plasma toroidal current in the toroidal region at steady state would be around 60 kA. The electrically non-conductive break in the shell (16) prohibits the flow of net toroidal current in the shell, which would otherwise act as a short-circuited secondary circuit for the induction winding. This aspect of the device and the basic design considerations thereof, especially for coils (42), such as energization through capacitor bank, are similar in the present invention to those in RFP and other ohmically heated toroidal plasma devices. Finally, the induction coils (42) and (46) may also conveniently serve for an additional purpose, namely, to supplement the shell (40) in shaping the plasma. Because magnetic flux diffuses through a shell with finite resistivity, the power of the shell to control the shape of the plasma is lost after the so-called T.sub.shell time. The currents in external conductors such as coils (42) and (46) may be distributed so as to provide magnetic boundary conditions identical to those of the shell. The field amplitudes to be produced are of order of 0.1 T in the mean for the illustrated embodiment. Shaping by external coils has been demonstrated in Doublet tokamaks experiments and, using this technique, the duration of the plasma is not limited by the T.sub.shell diffusion time. In FIG. 2, the individual turns of coils (42) and (46) are shown with a distribution that achieves the fundamental purpose. An infinitude of such distributions may be found, and satisfactory designs may also be obtained with different number of turns than illustrated. The general behaviour of relaxing plasmas within an open-ended vessel, containing at least a small magnetic field with open-ended field lines, can be deduced from Taylor's original theory of relaxation of plasmas in toroidal vessels. Although the helicity, as expressed in Equation (1), becomes ill-defined when the vessel boundary is not a magnetic flux-surface, an alternative quantity can be introduced with analogous properties (such "alternative helicity" has been discussed, e.g., by Finn, J. M. and Antonsen, T. M., Comments Plasma Phys. Controlled Fusion, 1985, Vol. 9, No. 3, pp. 111-126). In particular, its approximate conservation can be assumed during resistive relaxation, and minimization of the energy under this sole constraint and the appropriate boundary conditions yields again Equation (2) for the relaxed state. This extension of Taylor's relaxation theory describes the principal features of open-ended toroidal plasmas as observed in experiments. In particular, plasmas tend to approach the configuration described by Equation (2), independently of their initial state and the particular method used to produce them. There may be more than one solution to Eq. (2) in the given shell geometry with the given boundary conditions, in which case, Taylor's theory predicts that only the equilibrium with lowest energy is stable. However, higher energy solutions of Equation (2) may be found as more suitable equilibria for plasma confinement, in particular because they involve generally a higher magnetic shear. A principal object of the present invention, stated in the context of the preceding discussion, is to introduce an additional constraint in relaxation, to prevent decay to an unfavorable lower energy solution, by means of a homotopic invariant. For MHD systems admitting a homotopic invariant, this lowest energy solution is not available, if it belongs to a different homotopy class than the relaxing configuration. The magnetic field of an MHD system in an axisymmetric simply-connected vessel has more than one homotopy class provided two conditions are satisfied: 1. There is no three-dimensional null point in the plasma. This may be controlled by the external coils and mainly by the current driven by the electrodes which assure, in particular, that at poloidal null, the toroidal component is substantially far from zero. More generally, the higher the temperature of the resistive plasma, the larger the time-scale during which the development of such null-point is inhibited. PA0 2. In some vicinity of the major axis, the field has a normal component, and, on the remaining part of the vessel surface, the direction of the field is tangential and is nowhere antiparallel to its direction on the major axis. This latter condition can be simply obtained by external toroidal coils controlling the boundary poloidal field. PA0 1. Construct a conducting metal shaping shell whose shape is identical with the outermost magnetic surface of the desired state. PA0 2. Prior to formation of the plasma, establish a vertical magnetic field in the shaft region of the enclosed evacuated cylindrical volume, using coils (42). PA0 3. Inject the gas that will be ionized into plasma, using any conventional means. Optionally, the gas may be preionized. PA0 4. Establish a vertical electric field along the axis of the shaft region of the vessel by external electrodes so as to ionize the gas completely and drive a vertical current creating open poloidal field lines in this region. PA0 5. Let the straight-plasma column relax into the toroidal region. In virtue of Taylor principle, the plasma state reached will have for appropriate parameters a toroidal region with closed poloidal field lines and with toroidal component. Analogous technique of relaxation has been probed in several recent experiments on spheromak, RFP, and tokamak. If necessary, one may assist the desired relaxation process by using the shaping coils (46) at the boundary of the toroidal part of the vessel as inductive coils to create closed nested magnetic surfaces with relaxation to the desired Taylor state. This state however will not be a Dag, as there is no field reversal, and the separatrix, in general, involves two x-points on the wall. PA0 6. Reverse the direction of the axial current discharge between the electrodes, and the direction of the external vertical magnetic field (together with toroidal current component created by inductive coils around the axial region). Optional shaping coils (46) of the toroidal region may be maintained during this stage with same current orientation as in previous stage. This assures the proper boundary condition for the poloidal field and has for result to modify the separatrix to the desired one: one inner divertor with toroidal field reversed with respect to the direction of the toroidal component of the core of the toroidal region obtained in previous stage. PA0 7. Once the proper topology has been produced (toroidal component at the inner divertor reversed with respect to that at the elliptic axis), adjust electrode current and boundary poloidal field (by shaping coil) to level of the desired plasma state, so as to reach the optimally stable relaxed state of the resistive plasma. Gas may be let into the chamber slowly to replenish gas absorbed by the metal walls. PA0 8. The shape of the flux surface does not change radically as the mode amplitude ratio is changed within some controlled range. Therefore, a single shaping shell (16) can be used to study a continuum of neighboring equilibria by magnetically adjusting the boundary conditions by means of small currents through additional toroidal coils of various location exterior to said shell, as, for instance, in T. Okhawa U.S. Pat. No. 4,543,231 for shaping of multipinch plasma. PA0 9. The possibility of helicity injection by the electrodes along the vertical field produced by external coils allows for maintenance in a steady-state regime. Sustainment of Taylor state in steady state using helicity injection by means of electrodes has been realised in several spheromak and tokamak devices (such as in M. Ono et al., "Steady-State Tokomak Discharge via dc Helicity Injection", Physical Review Letters, Vol. 59, No. 19, Nov. 9, 1987). If said two conditions are maintained, then one has a homotopic invariant, related to the relative homotopy of .pi..sub.3 (S2), itself related to the so-called Hopf invariant (see Finkelstein, D. and Weil, D., the International journal of Theoretical Physics, Vol. 17, No. 3 (1978), pp. 201-217), which has an integer value K. The class with K=0 includes the configurations which have no toroidal field-reversal, to which the lowest energy Taylor's states belong. Thus, it is the object of the present invention to have a plasma equilibrium configuration with K different from zero. Present inventors have named such a configuration a Dag. In the case of axisymmetry, the presence of at least two magnetic axes with toroidal field of opposite sign, is a necessary crucial condition. Otherwise, one of the toroidal directions is certainly excluded from the total range of directions of the field configuration, and configurations where all possible azimuthal directions are not reached by the field always have K=0. For the simply-connected geometry of the plasma vessel considered in the present invention, with the above boundary conditions, a Dag configuration should possess at least one pair of elliptic and hyperbolic axes, the toroidal component of which are reversed one with respect to the other. The simplest example is the Topomak configuration, examples of which are given in the followings. The general nonsingular axisymmetrical solution in cylindrical coordinates of Equation (2) for Taylor equilibrium states is given by the Chandrasekhar-Kendall form: ##EQU4## The solution consists of the sum of linearly independent modes, specified by mode number k, with amplitude a.sub.k : J.sub.o and J.sub.1 are the Bessel functions of the first kind, respectively of order 0 and order 1. A topomak equilibrium has one pair of elliptic and hyperbolic axes with reversed toroidal orientation of one with respect to the other. This implies having the direction of B at midplane of symmetry performing at least one full rotation, as distance from major axis r increases. The k=0 mode alone realizes that, provided .mu..multidot.r can be as high as 7 within the vessel. However, this mode does not have closed magnetic surfaces. Thus, we consider as next simplest trial solution a superposition of the k=0 mode with one additional k mode. To prevent the occurrence of null points on the major axis (one of the conditions for the topological constraint), we impose .vertline.ak/ao.vertline.<1. Poloidal nulls are then located on midplane at the roots of the equation B.sub.z (r)=0. Thus, the first two consecutive roots should have opposite signature (signaling whether it is an 0 point or an X point) and opposite B.sub..phi.. One can show that this happens if k is sufficiently close to .mu. for a definite range of negative values of a.sub. k /a.sub.o. In addition, to obtain a Topomak, the separatrix originating at the X point should enclose the 0 point. For the convenient choice of .mu.=25, this is satisfied for k=22 provided -9.6<a.sub.k /a.sub.o <-4.5, and for k=23 provided -8.6<a.sub.k /a.sub.o <-3.8. Thus, diverted RFP Taylor states with non-zero homotopic invariant exist. Basically, the axial hard core of a conventional RFP system is replaced by a relaxed equilibrium of an axial straight plasma current channel, and the resultant is a Reversed-Field-Pinch with an inner reversed divertor Taylor state. Solutions with a higher topological number can be constructed in a similar manner. For example, a Dag with topological number K=2, consists of two toroidal current channels, forming together a doublet with a figure-eight-like separatrix, together with a vertical straight relaxation current channel with an inner divertor. The toroidal magnetic field at the two elliptic axes is in opposite direction to the direction of the toroidal field at both hyperbolic axes on the close and open-ended separatrices. It is clear that still higher K states can be readily constructed. It is also obvious that if one does not require the Dag to be in a Taylor state, the x point with reversed toroidal direction relative to the direction at the 0 point may be situated at other location than at most inboard location on the torus surface. FIGS. 4A and 4B illustrate plasmas with K=2, in their most symmetric orientations in axisymmetric geometry. Intermediate orientations could be possible, but they add complexity with no apparent increased benefit. The most straight-forward method to produce plasmas approximating a desired Taylor state is to: Axisynmetric plasma equilibria with finite plasma pressure and a general specified toroidal current density may be calculated by solving the finite pressure Grad-Shafranov equation. For instance, a family of solutions with pressure field function p(.psi.), specified arbitrarily, is obtained by adding ##EQU5## to the zero pressure toroidal flux solution .psi.. However, not all these solutions are stable. Mercier criterion allows for an estimate for the maximal pressure acceptable without driving an interchange instability, assuming that the back effects of the pressure on the magnetic field configuration can be reasonably neglected. The magnetic flux-surfaces of FIG. 1 are drawn from a numerical solution of the Grad-Shafranov equation with zero pressure. For FIG. 1 the aspect ratio A=R.sub.0 /a is 1.7, where R.sub.0 is the major radius of the elliptic axis and a is the half width of the toroidal plasma width at its widest point. The toroidal field on the separatrix is reversed and substantial, due to finite current along the vertical axis. Plots of B.sub.p, B.sub..phi., q and maximal p derived from this numerical solution are given in FIGS. 4A, 4B and 4C as a function of r at midplane z=0. Thus, the desired inner reversed divertor is still obtained with a realistic plasma current distribution by means of the present invention, consisting of a combination of straight and toroidal relaxing current channels generating a non-zero magnetic homotopic invariant. The occurrence of the non-zero homotopic invariant in the combination of straight and toroidal relaxing plasma regions can be explained in simplified qualitative terms. The toroidal magnetic field at the hyperbolic axis is reversed with respect to that of the elliptic axis. Moreover, the poloidal field at the boundary vessel is approximately parallel to that on the central axis. Therefore, the magnetic field, as it progresses from the central axis outwards to the boundary, at midplane, has performed a complete rotation of 360.degree. (or somewhat more). This corresponds to a closed circle on the sphere representing all possible directions. As the total surface of the poloidal cross-section is swept by an imaginary deformation of the z=0 chord, the sphere of directions is covered once. This yields K=1, which remains invariant under any deformation. If the toroidal field is not reversed, this implies that only a portion of the sphere of directions is covered. Thus, K is certainly zero. In the most common present art toroidal magnetic confinement systems, namely the tokamak and stellarators families, the toroidal field greatly exceeds the poloidal field; thus the toroidal field does not change sign, and therefore non-zero homotopic invariants cannot be obtained. In relaxation devices, such as the RFP, toroidal field strength is comparable to its poloidal counterpart, and can have a large variation across flux surfaces. Thus, in the topomak the toroidal field can be reversed at the separatrix, yielding the invariant. To strictly ensure the conservation of the homotopic invariant, it is required to prevent the possibility of null point occurrence, in particular at the poloidal null, and on the axis (as present in spheromak). For this reason, it is advantageous to operate the present invention with the geometric and current/field ratio parameters, such that the toroidal field reversal takes place well inside the separatrix surface. This implies a substantial axial current. Too high a current may, however, lead to a defavorable energy balance, due to heat dissipation along the open field lines, and it may as well reduce efficiency of transfer of helicity from the shaft region. The position of reversal within separatrix may be varied to obtain best plasma confinement and most efficient energy balance by experimental measurement. The present invention therefore provides a method for generating and maintaining magnetically torroidal plasma of the Reversed-Field-Pinch type with an inner poloidal divertor and without linking coils, by means of inserting a topological constraint. Having a RFP without linking coils is not possible in prior art RFP configurations. The present invention closely approximates a high energy Taylor state. The location of the topological invariant according to the present invention is such as to exert a stabilizing influence on global instabilities preventing decay to lower energy Taylor states with unfavourable magnetic shear, or to total reconnection to open field-lines. The location of the poloidal divertor implied by the invariant is also favorable for the amelioration of effects arising from the increased magnetic shear near the separatrix, as well as for effective impurity cure. Therefore, advantages of greater stability and/or greater .beta., generically termed improved plasma confinement, as well as technical advantages, specific to reacotor embodiment, may be expected compared with prior art RFP and spheromak devices. While the novel aspects of a magnetic confinement plasma device in accordance with the present invention have been shown in a preferred embodiment, many modifications and variations may be made therein within the scope of the invention, as in the size, shape, and current and field intensities, as well as in application of alternate methods and techniques well known in the art of plasma and fusion. For example, the axial current in the shaft region may be produced by other means than electrodes, as used in other devices for helicity injection. This includes electron beam injection along the open field lines. This includes also the possibility that the open-ended cylindrical vessel described in the invention may be an approximation of a larger closed toroidal vessel, in which case the axial discharge may be produced by inductive coils; such vessel can include along its axis more than one configuration as described in the invention. Moreover, the intermediate plasma state reached at stage 5 of the preferred method of production described above, may be obtained by other means. These include the injection in the vessel of a plasma ring produced by a coaxial-plasma source. One would then proceed along the same subsequent steps 6 to 9, as above. Additional possible variations include the adjunction of various standard means known to improve stability, such as the introduction of a conducting bar at the major axis of the shaft region. The particular embodiment described is designed for experimental and research purposes. Scaled-up embodiments intended for the production of a fusion and power reactor will likely include various additional well-known appurtenances of plasma and fusion devices, such as power supplies, vacuum pumps, instrumentation, auxiliary heating systems, blankets, heat exchangers, supporting structures and control systems.
	summary
	description	1. Field of the Invention The present invention relates to a laser irradiation apparatus and a laser irradiation method. 2. Description of the Related Art In recent years, extensive research has been conducted on laser crystallization methods used to crystallize a semiconductor film (for example, an amorphous semiconductor film) formed over a glass substrate through irradiation of the semiconductor film with laser light. Crystallization of a semiconductor film is performed in order to increase carrier mobility through crystallization of the semiconductor film. The crystallized semiconductor film is used, for example, in a thin film transistor (hereinafter described as a TFT). When a semiconductor film formed over a glass substrate has been crystallized, an active matrix display device (for example, a liquid crystal display device or an organic EL display device) can be manufactured through formation of a TFT for use in a pixel and TFT for use in a driver circuit, using the semiconductor film. Methods for crystallizing a semiconductor film, other than the laser crystallization method, include a thermal annealing method which uses an annealing furnace and a rapid thermal annealing method (RTA method). However, these methods need treatment at a high temperature greater than or equal to 600° C. Because of this, use of a quartz substrate that can withstand treatment at high temperature is necessary and causes manufacturing costs to increase. In comparison with these methods, since heat can be absorbed only by a semiconductor film in the laser crystallization method, the semiconductor film can be crystallized without increasing the temperature of the substrate very much. Therefore, a material with low heat resistance, such as glass or plastic, can be used for the substrate. Accordingly, an inexpensive glass substrate that can be easily processed with a large area can be used, and the production efficiency of the active matrix display device increases considerably. Conventionally, a method using an excimer laser which is a pulsed laser has been used as the laser crystallization method. Since a wavelength of an excimer laser belongs to an ultraviolet region, the laser can be efficiently absorbed by silicon and heat can be selectively applied to silicon. When an excimer laser is used, for example, laser light with a rectangular shape (for example, a rectangular shape with an area of 10 mm×30 mm) emitted from a laser oscillator is processed by an optical system into laser light with a linear cross section (for example, a linear cross section with an area of several hundreds of micrometers×300 mm). Then, a semiconductor film is irradiated with the linearly processed laser light while the laser light is moved relative to the semiconductor film, whereby the whole semiconductor film is crystallized sequentially. With the direction, in which the laser light is moved, being perpendicular relative to the laser light, crystallization efficiency increases. In comparison, in recent years, a technology for manufacturing a semiconductor film including a region with crystals of much larger grain size (also referred to as a large grain crystal region) than crystals of a semiconductor film crystallized by an excimer laser has been developed, in which the semiconductor film is irradiated with a continuous-wave (CW) laser or a pulsed laser with a repetition rate of 10 MHz or more to be processed into linear laser light, while the laser light is moved relatively to the semiconductor film. When this large grain crystal region is used as a channel region of a TFT in manufacturing the TFT, energy barriers against carriers (electrons or holes) decrease because fewer grain boundaries exist in the direction of the channel. As a result, the manufacture of a TFT that has a mobility of several hundreds of cm2/Vs becomes possible. (For example, see Patent Document 1: Japanese Published Patent Application No. 2005-191546). However, in general, energy intensity distribution in a major-axis direction of a continuous-wave (CW) laser or a pulsed laser with a repetition rate of 10 MHz or more, which is used in crystallizing a semiconductor film, is Gaussian distribution, which does not have uniform energy intensity distribution. That is, on both ends in a major-axis direction of laser light, a region having low energy intensity distribution is formed. Therefore, when the semiconductor film is crystallized using the laser light, at the same time as formation of the large grain crystal region, only a crystal grain the grain size of which is comparatively small (hereinafter described as a small grain crystal) is to be formed in the region having low energy intensity distribution in the end region in the major-axis direction of the laser light. Here, FIGS. 15A and 15B illustrate a schematic view of a surface of a semiconductor film when the semiconductor film is crystallized using laser light. FIG. 15A illustrates an irradiation track when the semiconductor film is irradiated with laser light 1501 used for laser irradiation. FIG. 15B illustrates an energy intensity distribution 1502 taken along a cross section A-A′ of the laser light 1501. In general, laser light emitted from a laser oscillator having a TEM00 mode (a single transverse mode) has energy intensity distribution of Gaussian distribution as illustrated in the energy intensity distribution 1502 of FIG. 15B, which does not have uniform energy intensity distribution. Note that FIG. 15B has a vertical axis which indicates an energy intensity, where an intensity (Y) is a threshold value in which a large grain crystal can be obtained at the irradiation and an intensity (X) is a threshold value in which a crystalline region can be formed. In FIG. 15A, a region 1503 near the center in the major-axis direction of the laser light 1501 is irradiated with laser light having energy intensity higher than that of the threshold value (Y) in which a large grain crystal can be obtained, so that a large grain crystal region is formed. At this time, laser light with which a region 1504 near the end in the major-axis direction of the laser light is irradiated has energy intensity higher than that of the threshold value (X) in which a crystalline region can be formed and lower than that of the threshold value (Y). Therefore, in the region 1504 near the end in the major-axis direction of the laser light, a region which is not completely dissolved remains partially; thus, not a large grain crystal region as formed in the region near the center but only a small grain crystal is to be formed. A small grain crystal region formed in such a manner, that is, the region near the end in the major-axis direction of the laser light is an aggregation of crystal grains the surface of which has marked unevenness; therefore, high characteristics cannot be obtained even when a semiconductor element is formed. In addition, since it is necessary to form a semiconductor element in the large grain crystal region in order to avoid this, it is apparent that there is limitation on layout. Therefore, it is necessary to control not to form the small grain crystal region in the entire region irradiated with the laser light. Thus, in view of the above problems, it is an object of the present invention to provide a laser irradiation apparatus and a laser irradiation method that can form a large grain crystal region also in an end region in a major-axis direction of laser light by having high energy intensity distribution in the end region in the major-axis direction of the laser light. Note that a direction of laser light that is extended longer is to be referred to as a major-axis direction or a longitudinal direction of the laser light, and a direction of a shorter axis is to be referred to as a minor-axis direction or a width direction of the laser light in this specification. According to one feature of a structure relating to a laser irradiation apparatus of the present invention, a laser oscillator which oscillates laser light; an optical element which converges the laser light in one direction; and a means which shields an end region in a major-axis direction of the laser light, which is disposed between the optical element and an irradiation surface are included. In the laser irradiation apparatus, energy intensity distribution in the irradiation surface is precipitously high in the end region in the major-axis direction of the laser light, and energy intensity distribution in the irradiation surface is higher in the end region in the major-axis direction of the laser light than a central region in the major-axis direction of the laser light. According to another feature of the structure relating to the laser irradiation apparatus of the present invention, a laser oscillator which oscillates laser light; an optical element which converges the laser light in one direction; and a means which shields an end region in a major-axis direction of the laser light, which is disposed between the optical element and an irradiation surface are included. In the laser irradiation apparatus, when a distance between the means which shields the end region in the major-axis direction of the laser light and the irradiation surface is L μm and a wavelength of the laser light oscillated from the laser oscillator is λ μm, the means which shields the end region in the major-axis direction of the laser light is disposed at a position which satisfies 0.5<Lλ<100; energy intensity distribution in the irradiation surface is precipitously high in the end region in the major-axis direction of the laser light; and energy intensity distribution in the irradiation surface is higher in the end region in the major-axis direction of the laser light than a central region in the major-axis direction of the laser light. According to another feature of the structure relating to the laser irradiation apparatus of the present invention, a laser oscillator which oscillates laser light; an optical element which converges the laser light in one direction; and a means which shields an end region in a major-axis direction of the laser light, which is disposed between the optical element and an irradiation surface are included. In the laser irradiation apparatus, when a distance between the means which shields the end region in the major-axis direction of the laser light and the irradiation surface is L μm, the means which shields the end region in the major-axis direction of the laser light is disposed at a position which satisfies 1<L<200; energy intensity distribution in the irradiation surface is precipitously high in the end region in the major-axis direction of the laser light; and energy intensity distribution in the irradiation surface is higher in the end region in the major-axis direction of the laser light than a central region in the major-axis direction of the laser light. According to one feature of a structure relating to a laser irradiation method of the present invention, laser light is oscillated from a laser oscillator; the laser light emitted from the Laser oscillator passes through an optical element; the laser light which passes through the optical element passes through a means which shields an end region in a major-axis direction of the laser light; and, by passing through the means which shields an end region in a major-axis direction of the laser light, irradiation of laser light, in which energy intensity distribution is precipitously high in the end region in the major-axis direction of the laser light and energy intensity distribution is higher in the end region in the major-axis direction of the laser light than a central region in the major-axis direction of the laser light, is performed to an irradiation surface. According to another feature of the structure relating to the laser irradiation method of the present invention, laser light is oscillated from a laser oscillator; the laser light emitted from the laser oscillator passes through an optical element; the laser light which passes through the optical element passes through a means which shields an end region in a major-axis direction of the laser light; by passing through the means which shields the end region in the major-axis direction of the laser light, irradiation of laser light, in which energy intensity distribution is precipitously high in the end region in the major-axis direction of the laser light and energy intensity distribution is higher in the end region in the major-axis direction of the laser light than a central region in the major-axis direction of the laser light, is performed to an irradiation surface; and, when a distance between the means which shields the end region in the major-axis direction of the laser light and the irradiation surface is L μm and a wavelength of the laser light oscillated from the laser oscillator is λ μm, the means which shields the end region in the major-axis direction of the laser light is disposed at a position which satisfies 0.5<Lλ<100. According to another feature of the structure relating to the laser irradiation method of the present invention, laser light is oscillated from a laser oscillator; the laser light emitted from the laser oscillator passes through an optical element; the laser light which passes through the optical element passes through a means which shields an end region in a major-axis direction of the laser light; by passing through the means which shields the end region in the major-axis direction of the laser light, irradiation of laser light, in which energy intensity distribution is precipitously high in the end region in the major-axis direction of the laser light and energy intensity distribution is higher in the end region in the major-axis direction of the laser light than a central region in the major-axis direction of the laser light, is performed to an irradiation surface; and when a distance between the means which shields the end region in the major-axis direction of the laser light and the irradiation surface is L μm, the means which shields the end region in the major-axis direction of the laser light is disposed at a position which satisfies 1<L<200. In the present invention, either a continuous-wave laser oscillator or a pulsed laser oscillator can be used for the laser oscillator, and one or more of the following are used as the laser oscillator: a gas laser such as an Ar laser, a Kr laser, or an excimer laser; a laser using as a medium single crystalline YAG, YVO4, forsterite (Mg2siO4), YAlO3, or GdVO4, or polycrystalline (ceramic) YAG, Y2O3, YVO4, YAlO3, or GdVO4, to which one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, or Ta is added as a dopant; a glass laser, a ruby laser, an alexandrite laser, a Ti:sapphire laser, a copper vapor laser, or a gold vapor laser. In particular, a laser having high interference such as single crystalline or polycrystalline (ceramic) YVO4, YAG, GdVO4, or YLF is appropriate for implementation of the present invention. The reason why the laser having high interference is appropriate is that the laser is appropriate to form energy intensity distribution, which is extremely precipitous, in an end region in a major-axis direction of laser light. In the pulsed laser oscillator, although a frequency band of several tens to several hundreds Hz is generally used, a pulsed laser with a repetition rate of 10 MHz or more may also be used. When a pulsed laser having a high repetition rate is used, there is such an advantage: a period after a semiconductor film is irradiated with laser light and before the semiconductor film is completely solidified is said to be several tens to several hundred n sec. With a pulsed laser having a low repetition rate, a semiconductor film is irradiated with the next pulse after being melted and solidified by laser light. Therefore, after the semiconductor film is irradiated with each pulse, crystal grains grow radially in a centrosymmetric manner at the time of recrystallization. Then, since grain boundaries are formed at boundaries between the adjacent crystal grains, the surface of the semiconductor film becomes uneven. On the other hand, when a pulsed laser with a high repetition rate is used, laser light is delivered to a semiconductor film before the semiconductor film melted by the previous laser light is solidified. Therefore, unlike in the case where a pulsed laser with a low repetition rate is used, an interface between a solid phase and a liquid phase in the semiconductor film can be moved continuously. Consequently, a semiconductor film having crystal grains, which grow continuously in a direction where the laser light is moved, can be formed. In addition, one of features of the pulsed laser is that peak output per pulse can be raised by increasing the repetition rate. Therefore, conversion efficiency of laser light into a second harmonic can be significantly increased even in the case where the average output is comparatively low. Accordingly, since a harmonic with high output can be obtained easily, the productivity can be improved significantly. In the case where a laser oscillator that includes a single-crystal medium is used, laser light is formed into laser light with a length of 0.5 to 1 mm in a major-axis direction and a length of less than or equal to 20 μm, preferably less than or equal to 10 μm, in a minor-axis direction on an irradiation surface. The laser beam is moved in the minor-axis direction. Consequently, an aggregation of crystal grains each having a width of 10 to 30 μm in a scanning direction of the laser light and approximately 1 to 5 μm in a direction perpendicular to the scanning direction can be formed the entire surface of a region irradiated with the laser light. In this way, a crystal grain with a similar size to a crystal grain obtained by using a continuous-wave (CW) laser can be obtained. By forming a crystal grain extending long in the scanning direction of the laser light, it is possible to form a semiconductor film having almost no crystal grain boundaries at least in a moving direction of carriers in a TFT. In the case where a laser oscillator that includes a polycrystalline medium is used, laser light can be emitted with extremely high output. In such a case, the size of the laser light can be enlarged. The length of a minor axis of the laser light may be set to be less than or equal to 1 mm, and that of the major axis is set so that a semiconductor film can be favorably annealed. In the present invention, as the optical element, a diffractive optical element such as a holographic optical element or a binary optical element, or a cylindrical lens can be used. Moreover, a thin film transistor (TFT) is formed with a crystalline semiconductor film formed by applying the present invention, and a semiconductor device is manufactured by using the TFT. As the semiconductor device, typically, a central processing unit (CPU), a memory, an IC, an RFID element, a pixel, a driver circuit, and the like can be given. Further, by incorporating these semiconductor devices, various electronic devices can be formed, such as a television, a computer, and a mobile information-processing terminal. With the use of the laser irradiation apparatus and the laser irradiation method of the present invention, a region where energy intensity distribution is precipitously high in an end region in a major-axis direction of laser light in the irradiation surface can be formed. Therefore, by applying the present invention, a surface of an amorphous semiconductor film is irradiated with laser light, whereby large grain crystals can be formed in the entire region irradiated with the laser light. Thus, the laser irradiation can be performed favorably. In addition, a crystalline grain region (a small grain crystal region) having an uneven surface, which is rough, formed in the end region in the major-axis direction of the laser light, comes not to be formed, and coverage in forming a thin film over a crystallized semiconductor film will be favorable in a subsequent step. The entire region irradiated with the laser light can be used to form a semiconductor element; thus, a rule of a circuit design is relaxed. Embodiment modes of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following description, and those skilled in the art can easily understand that modes and details of the present invention can be changed in various ways without departing from the purpose and the scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiment modes below. Note that the same portions or portions having the same function in the structure of the present invention described below are denoted by the same reference numerals in common among different drawings and repetitive description thereof will be omitted. (Embodiment Mode 1) This embodiment mode will show an example of a laser irradiation apparatus and a laser irradiation method of the present invention. A laser irradiation apparatus illustrated in FIGS. 1A and 1B has a laser oscillator 101, an optical element 102, and a slit 103. In this embodiment mode, the case will be described where the slit 103 is used as a means which shields an end region in a major-axis direction of laser light which is emitted from a laser oscillator. The laser oscillator 101 used in this embodiment mode is not particularly limited, and either a continuous-wave laser oscillator or a pulsed laser oscillator can be used. For example, a laser oscillated from one or more of the following can be used: a gas laser such as an Ar laser, a Kr laser, or an excimer laser; a laser using, as a medium, single crystalline YAG, YVO4, forsterite (Mg2SiO4), YAlO3, or GdVO4, or polycrystalline (ceramic) YAG, Y2O3, YVO4, YAlO3, or GdVO4, to which one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, or Ta is added as a dopant; a glass laser, a ruby laser, an alexandrite Laser, a Ti:sapphire laser, a copper vapor laser, or a gold vapor laser. Note that a laser having high interference such as single crystalline or polycrystalline (ceramic) YVO4, YAG, GdVO4, or YLF is appropriate, which is preferable. This is because a region where energy intensity distribution is precipitously high is formed in the end region in the major-axis direction of laser light when such a laser is used. Laser light oscillated from the laser oscillator 101 enters into the optical element 102. In this embodiment mode, the case where a cylindrical lens is used as the optical element 102 is described. Note that the cylindrical lens operates so as to converge laser light in one direction and forms a cross-sectional shape of the laser light into a linear shape relative to an irradiation surface. Light in the end region in the major-axis direction of the laser light, which passes through the optical element 102, passes through the slit 103 disposed between the cylindrical lens and the irradiation surface, thereby being shielded. An irradiation surface 104 is irradiated with laser light that is not shielded by the slit 103. FIG. 2A illustrates energy intensity distribution in the major-axis direction of the laser light with which the irradiation surface 104 is irradiated. As illustrated in FIG. 2A, in the end region in the major-axis direction of the laser light, a region where energy intensity distribution is precipitously high is formed. This is because the end region in the major-axis direction of the laser light is shielded using the slit 103, so that a phenomenon referred to as diffraction due to laser interference occurs. The region where the energy intensity distribution is precipitously high is formed, so that decrease in energy intensity distribution in the end region of the laser light can be prevented. Therefore, the entire surface of the region irradiated with the laser light can be irradiated with laser light having enough energy intensity. The energy intensity distribution in the end region in the major-axis direction of the laser light of this case is increased by 30 percent in comparison with the case in which the slit 103 is not disposed. In addition, the energy intensity distribution in the end region in the major-axis direction of the laser light can be made higher than energy intensity distribution in a central region in the major-axis direction of the laser light by using the slit 103. Therefore, even when heat is diffused outside of a boundary of an irradiation region of the laser light in irradiating a substrate with the laser light, decrease in temperature of a substrate surface in the boundary region can be prevented. Thus, a surface of an amorphous semiconductor film is irradiated with such laser light, whereby a small grain crystal region can be prevented from being formed near an end of the irradiation region of the laser light. Therefore, a large grain crystal region can be formed in an entire region of a surface of the semiconductor film irradiated with the laser light. Further, since the entire region irradiated with the laser light can be used to form a semiconductor element, a rule of a circuit design is relaxed. In addition, the entire energy intensity distribution of the laser light is increased and the energy intensity distribution in the end region in the major-axis direction of the laser light is further increased, whereby a microcrystalline grain the surface of which has less unevenness can be formed. In addition, an ablation process (a process using a phenomenon that molecular bond in a portion irradiated with laser light, that is, a portion that absorbs laser light is broken, photodecomposition of the portion occurs, and the portion is vaporized) can also be performed. Accordingly, a crystalline grain region (a small grain crystal region) having an uneven surface, which is rough, formed in the end region in the major-axis direction of the laser light, comes not to be formed and coverage in forming a thin film over a crystallized semiconductor film will be favorable in a subsequent step. The width of the end region is within several μm, which is extremely narrow; therefore, almost the entire region irradiated with the laser light can be used to form a semiconductor element; thus, a rule of a circuit design is relaxed. In this embodiment, the laser light is formed using the cylindrical lens; however, the optical element 102 is not particularly limited as long as an optical element that converges laser light in one direction (forms a cross section of laser light into a linear shape or a rectangular shape) is used. For example, a diffractive optical element may be used. As a typical example of a diffractive optical element, a holographic optical element, a binary optical element, and the like can be given. A diffractive optical element is also referred to as a diffractive optics or a diffractive optics element, which is an element that can obtain a spectrum using diffraction of light. Then, the laser light emitted from the laser oscillator can be formed into linear or rectangular laser light with uniform energy intensity distribution by using the diffractive optical element. When the laser light having the linear shape or the rectangular shape with the uniform energy intensity distribution is made to pass through the slit used in this embodiment mode by the diffractive optical element, as illustrated in FIG. 2B, the region where the energy intensity distribution is precipitously high in the end region in the major-axis direction of the laser light in the irradiation surface can be formed. In addition, as the convexity of the cylindrical lens, a cylindrical lens having a convex surface either on an incidence side or an emission side, or having convex surfaces on both sides may be used. However, in consideration of low aberration and accuracy, a cylindrical lens having a convex surface on an incidence side is preferably used. The slit 103 is disposed at a position apart from the irradiation surface 104 by a distance L [μm]. When a wavelength of the laser light oscillated from the laser oscillator 101 is to be λ [μm], a growth direction of crystals and a crystallization position can be controlled by disposing the slit 103 at a position that satisfies 0.5<Lλ<100. Accordingly, the crystallization direction can be made constant, a large grain crystal region can be formed on a surface of a semiconductor film, and a surface of the crystallized film can be planarized. The slit 103 used in this embodiment mode is not particularly limited. A slit that has a structure or a shape capable of shielding an end region in a major-axis direction of laser light when the laser light passes through the slit can be used. For example, light shielding is performed using the plate slit 103 as illustrated in FIGS. 1A and 1B or a slit having a rectangular opening. The slit 103 can adjust the position depending on kinds of laser light or energy, and the size of the opening of the slit 103 can be adjusted. In the laser irradiation apparatus of the present invention, the slit 103 is provided so that the opening is parallel to a scanning direction of a beam spot 105, and the width of the opening of the slit is to be constant in a scanning range. Accordingly, the end region in the major-axis direction of the laser light can be shielded and the length in the major-axis direction of the beam spot 105 can be adjusted at the same time. In addition, the slit can also be formed using a reflecting mirror. Deformation of the slit can be prevented without absorbing heat by using a reflecting mirror. Therefore, stable laser light can be obtained. As illustrated in FIG. 1B, a reflecting mirror may be disposed by inclining a reflective surface to a direction that laser light make incidence. Moreover, laser light that is reflected by the reflecting mirror is preferably absorbed using a damper. By using the laser irradiation apparatus and the laser irradiation method of this embodiment mode, the region where the energy intensity distribution is precipitously high in the end region in the major-axis direction of the laser light can be formed. Therefore, a large grain crystal region can be formed in all regions irradiated with the laser light, so that the laser irradiation can be favorably performed. For example, by using the laser irradiation apparatus and the laser irradiation method described in this embodiment mode, a large grain crystal region can be formed in all regions irradiated with the laser light in crystallizing a semiconductor film; thus, the entire surface of the semiconductor film can be favorably crystallized. (Embodiment Mode 2) This embodiment mode will describe a manufacturing method of a TFT using the laser irradiation apparatus or the laser irradiation method described in Embodiment Mode 1 with reference to drawings. Note that this embodiment will describe a manufacturing method of a top-gate (staggered) TFT; however, the present invention is applicable not only to the top-gate TFT but also, similarly, to a bottom-gate (inverted staggered) TFT or the like. As illustrated in FIG. 5A, a base film 501 is formed over a substrate 500 having an insulating surface. In this embodiment mode, a glass substrate is used as the substrate 500. As the substrate used here, a glass substrate made of barium borosilicate glass, aluminoborosilicate glass, or the like; a quartz substrate; a ceramic substrate; a stainless steel substrate; or the like can be used. Although a substrate made of a synthetic resin typified by acrylic or plastic which is represented by PET, PES, or PEN tends to have lower heat resistance than other substrates in general, the substrate can be used as long as the substrate can resist the process of this step. The base film 501 is provided in order to prevent the diffusion of alkaline earth metal or alkali metal such as sodium from the substrate 500 into the semiconductor. Alkaline earth metal and alkali metal cause adverse effects on characteristics of a semiconductor element when such metal is in the semiconductor film. Therefore, the base film 501 is formed by using an insulating film which can prevent the diffusion of alkaline earth metal and alkali metal into the semiconductor, such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film. The base film 501 is formed either in a single-layer or stacked-layer structure. In this embodiment, a silicon nitride oxide film is formed with a thickness of 10 to 400 nm by a plasma CVD (Chemical Vapor Deposition) method. It is effective to provide the base film in order to prevent the diffusion of the impurity when the substrate 500 containing even a little amount of alkaline earth metal or alkali metal, such as a glass substrate or a plastic substrate, is used. However, when a substrate in which the diffusion of the impurity does not lead to a significant problem, for example a quartz substrate, is used, the base film 501 is not necessarily provided. Next, an amorphous semiconductor film 502 is formed over the base film 501. The amorphous semiconductor film 502 is formed with a thickness of 25 to 100 nm (preferably thickness of 30 to 60 nm) by a sputtering method, an LPCVD method, a plasma CVD method, or the like. The amorphous semiconductor film used here can be formed using silicon, silicon germanium (SiGe), or the like. Note that silicon is used here. In the case where silicon germanium (SiGe) is used, it is preferable that the concentration of germanium be approximately 0.01 to 4.5 atomic %. Subsequently, as illustrated in FIG. 5B, the amorphous semiconductor film 502 is irradiated with laser light 503 to be crystallized. Here, an example of a laser irradiation apparatus and a laser irradiation method used for the laser irradiation is described with reference to FIG. 3. The laser irradiation apparatus illustrated in FIG. 3 has a laser oscillator 101, an optical element 102, a slit 103, a mirror 302, a suction stage 306, an X-axis stage 307, and a Y-axis stage 308. As the laser oscillator 101, the optical element 102, and the slit 103, ones similar to those illustrated in FIGS. 1A and 1B can be used. Note that the mirror 302 is not necessarily provided. Further, the mirror 302 may not be provided, if not necessary. In this embodiment mode, a substrate in which a semiconductor film 305 is formed is provided over the suction stage 306. Note that an insulating material is used as a material of the substrate. In addition, an amorphous semiconductor film may be used as the semiconductor film 305. However, a microcrystal semiconductor film or a crystalline semiconductor film can also be used. The entire surface of the semiconductor film 305 can be irradiated with laser light by scanning the suction stage 306 in X-axis or Y-axis direction along a surface of the semiconductor film 305 using the X-axis stage 307 and the Y-axis stage 308. Thus, the entire surface of the semiconductor film 305 can be crystallized favorably. This embodiment mode has a structure in which the substrate in which the semiconductor film 305 is formed is moved using the X-axis stage 307 and the Y-axis stage 308. Note that any one of the following methods can be used in order to move the laser light: an irradiation system moving method in which the substrate as an object is fixed while an irradiation position of the laser light is moved; an object moving method in which the irradiation position of the laser light is fixed while the substrate is moved; and a method in which these two methods are combined. In this embodiment mode, a continuous-wave (CW) laser (an Nd:YVO4 laser having a second harmonic (wavelength: 532 nm)) is used as the laser light 503. It is not necessary to limit particularly to a second harmonic; however, a second harmonic is superior to a further higher order harmonic in terms of energy efficiency. When the semiconductor film is irradiated with the continuous-wave (CW) laser, energy is continuously provided to the semiconductor film. Therefore, once the semiconductor film has been brought to a molten state, the molten state can be maintained. Further, an interface between a solid phase and a liquid phase of the semiconductor film can be moved by scanning the continuous-wave (CW) laser light, so that crystal grains long in one direction, to which the laser moves, can be formed. Not only the above laser light but also the continuous-wave (CW) laser shown in Embodiment Mode 1 or a pulsed laser with a repetition rate of 10 MHz or more can also be used. When the highest value of energy intensity distribution of the laser light is to be 100%, the size of an opening of the slit 103 used in FIG. 3 may be adjusted so that the laser light is shielded at greater than or equal to 60%, preferably greater than or equal to 80%, of the highest value of the energy intensity distribution of the laser light. When the laser light is shielded at greater than or equal to 80% of the highest value of the energy intensity distribution of the laser light, energy intensity distribution in the end region in the major-axis direction of the laser light can be made higher than energy intensity density in a central part in the major-axis direction of the laser light. Consequently, a large grain crystal can be formed in the entire region of the semiconductor surface irradiated with the laser. In addition, a microcrystal grain the surface of which has less unevenness can be formed or an ablation process can be performed. In this embodiment mode, a second harmonic (wavelength: 532 nm) of an Nd: YVO4 laser is used for crystallization of the semiconductor film. Therefore, in order to perform crystal growth in the major-axis direction of the laser light, the distance L between the slit and the irradiation surface is 1 to 200 μm, preferably 3 to 100 μm, more preferably 10 to 50 μm, and much more preferably 30 to 50 μm. In this case, the wavelength λ of the laser light is not limited to 532 nm. For example, an appropriate range of the above distance L is applied even in the case of the wavelength 527 nm like a second harmonic of an YLF laser. Further, the diffraction phenomenon depends on the wavelength of the laser light, and there is an inversely proportional relationship between the wavelength of the laser light λ and the distance L to obtain a similar diffraction image. Therefore, the appropriate range of the distance L which satisfies 0.5<Lλ<100 may be used by calculation as appropriate when laser light, the wavelength of which differs vastly from that of the above example, is used. The laser light emitted from the laser oscillator is converged in one direction by the optical element, and a cross-sectional shape of the laser light is formed into a linear shape relative to the irradiation surface. After that, the semiconductor film 305 is irradiated with the laser light after passing through the slit 103 disposed between the optical element 102 and the semiconductor film 305. With the use of the laser irradiation apparatus of this embodiment mode, a region where the energy intensity distribution is precipitously high in the end region in the major-axis direction of the laser light can be formed. By scanning the laser light to the amorphous semiconductor film, not only a crystal grain which is continuously grown in a lateral direction in both the ends in the major-axis direction of the laser light but also formation of a small grain crystal region or unevenness can be suppressed in a boundary of the adjacent laser irradiation regions. In such a manner, laser irradiation is favorably performed to the entire surface of the semiconductor film 305 by irradiating the semiconductor film with the laser light. Consequently, characteristics of the semiconductor device manufactured using this semiconductor film, which is favorable and uniform, can be obtained. The case where the plate slit is described with reference to FIGS. 1A and 1B and FIG. 3 is used; however, the present invention is not limited thereto and such a slit 403 as the opening of which is to be circular or elliptical may be used as illustrated in FIG. 4. A laser irradiation apparatus illustrated in FIG. 4 has a laser oscillator 101, an optical element 102, a slit 403, a mirror 302, a suction stage 306, an X-axis stage 307, and a Y-axis stage 308. As the laser oscillator 101, the optical element 102, the mirror 302, the suction stage 306, the X-axis stage 307, and the Y-axis stage 308, ones similar to those illustrated in FIG. 3 can be used. After that, as illustrated in FIG. 5C, a crystalline semiconductor film 505 formed by laser irradiation is etched into a predetermined shape, thereby forming an island-shaped semiconductor film 506. Moreover, a gate insulating film 507 is formed so as to cover this island-shaped semiconductor film 506. The gate insulating film 507 only needs to be an insulating film containing at least oxygen or nitrogen and may have a single layer or multilayer structure. The gate insulating film 507 can be formed by a plasma CVD method or a sputtering method. In this embodiment mode, a silicon nitride oxide film (SiNxOy (x>y, x and y=1, 2, 3 . . . )) and a silicon oxynitride film (SiOxNy (x>y, x and y=1, 2, 3 . . . ) are continuously formed by a plasma CVD method with a total thickness of 115 nm. In the case where a TFT with a channel length of 1 μm or less (such a TFT is also referred to as a submicron TFT) is formed, the gate insulating film is preferably formed with a thickness of 10 to 50 nm. Next, a conductive film is formed over the gate insulating film 507 and etched into a predetermined shape, thereby forming a gate electrode 508. The conductive film formed over the gate insulating film 507 may be a film having conductivity, and a stacked-layer film of tungsten and tantalum nitride is used in this embodiment mode. However, a conductive film in which Mo (molybdenum), Al (aluminum), and Mo are sequentially stacked by using Al and Mo, or a conductive film in which Ti (titanium), Al, and Ti are sequentially stacked by using Ti and Al may be used. Moreover, an element of gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), molybdenum (Mo), tungsten (W), or titanium (Ti), or an alloy or compound material containing the above element as its main component can also be used. Further, these materials may be stacked. Then, a resist mask for pattern processing of this conductive film is formed. First, coating of a photoresist is performed by a spin coating method or the like over the conductive film and then light exposure is performed. Next, heat treatment (pre-baking) is performed to the photoresist. The temperature for the pre-baking is set to 50 to 120° C., which is lower than the temperature at post-baking to be performed later. In this embodiment mode, the heat temperature is set to 90° C. and the heat time is set to 90 seconds. Subsequently, the light-exposed resist is developed by dropping a liquid developer or spraying a liquid developer from a spray nozzle onto the photoresist. After that, heat treatment (post-baking) is performed at 125° C. for 180 seconds to the developed photoresist. Thus, moisture and the like remaining in the resist mask are removed and, at the same time, the stability against heat is increased. The resist mask is formed according to these steps. Based on the resist mask, the conductive film is etched into a predetermined shape to form the gate electrode 508. As another method, the gate electrode 508 may be formed directly on the gate insulating film 507 by a printing method capable of discharging a material at a predetermined location or a droplet discharging method typified by an ink jet method. As the material to be discharged, a conductive material which is dissolved or dispersed in a solvent is used. As the material of the conductive film, at least one kind of gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), chromium (Cr), palladium (Pd), indium (In), molybdenum (Mo), nickel (Ni), lead (Pb), iridium (Ir), rhodium (Rh), tungsten (W), cadmium (Cd), zinc (Zn), iron (Fe), titanium (Ti), zirconium (Zr), barium (Ba), or the like, or alloy containing any of these elements is used. As the solvent, may be any of esters such as butyl acetate or ethyl acetate, alcohols such as isopropyl alcohol or ethyl alcohol, an organic solvent such as methyl ethyl ketone or acetone, or the like can be used. The viscosity of the composition is set to be less than or equal to 0.3 Pa·s. This is to prevent the composition from being dried and to facilitate the discharging of the composition from a nozzle. The viscosity and surface tension of the composition may be adjusted as appropriate in accordance with the solvent to be used and the intended purpose. Then, the gate electrode 508 or the resist used when the gate electrode 508 is formed is used as the mask to selectively add impurities imparting n-type or p-type conductivity into the island-shaped semiconductor film 506. Thus, a source region 509, a drain region 510, an LDD region 511, and the like are formed. By the above steps, N-channel TFTs 512 and 513, and a P-channel TFT 514 are formed over one substrate as illustrated in FIG. 5D. Subsequently, an insulating film 515 is formed as protective films of the N-channel TFTs 512 and 513, and the P-channel TFT 514. This insulating film 515 is formed with a thickness of 100 to 200 nm in a single-layer or stacked-layer structure of a silicon nitride film or a silicon nitride oxide film, by a plasma CVD method or a sputtering method. In the case where a silicon nitride oxide film and a silicon oxynitride film are combined, these films can be continuously formed by switching gas. In this embodiment mode, a silicon oxynitride film with a thickness of 100 nm is formed by a plasma CVD method. By providing the insulating film 515, it is possible to obtain a blocking effect to prevent the intrusion of various ionic impurities in addition to oxygen and moisture in the air. Subsequently, an insulating film 516 is formed. Here, the insulating film 516 can be formed by using an organic resin film such as polyimide, polyamide, BCB (benzocyclobutene), acrylic, or siloxane, the coating of which is performed by an SOG (Spin On Glass) method or a spin coating method. Moreover, an inorganic interlayer insulating film (an insulating film containing silicon such as silicon nitride or silicon oxide), a low-k (low dielectric) material, or the like can also be used. Since the insulating film 516 is formed with a main purpose for relaxing unevenness due to TFTs formed over the glass substrate to make the insulating film 516 flat, a film superior in flatness is preferable. Note that siloxane is a material whose skeletal structure includes a bond of silicon (Si) and oxygen (O) and whose substituent is either an organic group including at least hydrogen (such as an alkyl group or an aryl group) or a fluoro group. Further, the gate insulating film 507, the insulating film 515, and the insulating film 516 are pattern processed by a photolithography method, thereby forming contact holes that reach the source region 509 and the drain region 510. Next, a conductive film is formed with a conductive material and pattern processed, thereby forming a wiring 517. After that, an insulating film 518 is formed as a protective film. Thus, TFTs as illustrated in FIG. 5D is completed. By manufacturing a TFT with the crystalline semiconductor film which is manufactured using the laser irradiation apparatus of this embodiment mode, the performance of the TFT can be drastically improved. For example, since the number of crystal grain boundaries included in a channel formation region can be decreased, it is possible to obtain electric field-effect mobility (also referred to as mobility, simply) which is greater than or equal to that of a TFT using a single-crystal semiconductor and to decrease variation in an on-current value (the amount of drain current flowing when a TFT is in an on-state), an off-current value (the amount of drain current flowing when a TFT is in an off-state), threshold voltage, an S value, and electric field-effect mobility. With these advantageous effects, electrical characteristics of the TFT improves and the operating characteristic and reliability of the semiconductor device using the TFT improve. In particular, since there are almost no grain boundaries in a direction where the laser beam is moved, TFT characteristics preferably improve when channel formation region of the TFT is formed along this direction. The method for manufacturing a semiconductor device by using the laser irradiation method of the present invention is not limited to the above manufacturing process of a TFT. In addition, a crystallization step using a catalytic element may be provided prior to the crystallization by the laser light. As the catalytic element, nickel (Ni), germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum (Pt), copper (Cu), or gold (Au) can be used. The laser irradiation may be performed after the catalytic element is added to promote the crystallization through heat treatment, or the heat treatment may be omitted. Alternatively, after the heat treatment, a laser process may be performed while keeping the temperature. Although this embodiment mode shows the example of using the laser irradiation apparatus of the present invention to crystallize the semiconductor film, the laser irradiation apparatus of the present invention may be used to activate the impurity elements doped to the semiconductor film. Moreover, the method for manufacturing a semiconductor device according to the present invention can also be applied to a method for manufacturing an integrated circuit or a semiconductor display device. According to the present invention, laser irradiation is performed to the semiconductor film homogeneously. Therefore, if TFTs are manufactured using the semiconductor film by the method according to the present invention, all the TFTs have favorable characteristics and the characteristics of the respective TFTs are uniform. This embodiment can be freely combined with any of other embodiment modes and embodiments. (Embodiment Mode 3) This embodiment mode will describe a manufacturing method of a semiconductor device using the laser irradiation apparatus or a laser irradiation method shown in Embodiment Mode 1 with reference to drawings. First, a peeling layer 602 is formed over a substrate 601 made of glass by a sputtering method as illustrated in FIG. 6A. The peeling layer 602 can be formed by a sputtering method, a low-pressure CVD method, a plasma CVD method, or the like. In this embodiment mode, the peeling layer 602 is formed with amorphous silicon in thickness of approximately 50 nm by a low-pressure CVD method. The material of the peeling layer 602 is not limited to silicon and a material which can be selectively etched away (such as W or Mo) may be used. The thickness of the peeling layer 602 preferably ranges from 50 to 60 nm. Next, a base insulating film 603 is formed over the peeling layer 602. The base insulating film 603 is provided so as to prevent alkaline earth metal or alkali metal such as Na included in the substrate 601 from diffusing to the semiconductor film. Alkali metal and alkaline earth metal cause adverse effects on characteristics of a semiconductor element such as a TFT when the metal is in the semiconductor film. Moreover, the base insulating film 603 also has a function to protect the semiconductor element in a later step of peeling the semiconductor element. The base insulating film 603 can be formed with a single insulating film or a plurality of insulating films that are stacked. Therefore, an insulating film which can suppress the diffusion of alkali metal and alkaline earth metal into the semiconductor, such as a silicon oxide film, a silicon nitride film, a silicon oxide film containing nitrogen (SiON), or a silicon nitride film containing oxygen (SiNO) is used. Next, an amorphous semiconductor film 604 is formed over the base insulating film 603. The amorphous semiconductor film 604 is formed with a thickness of 25 to 200 nm (preferably, with thickness of 30 to 150 nm) by a sputtering method, an LPCVD method, a plasma CVD method, or the like. Laser light irradiation is performed to the amorphous semiconductor film 604 to be crystallized, similarly to Embodiment Mode 2. The amorphous semiconductor film 604 can be uniformly crystallized by using the above laser irradiation method. Note that the peeling layer 602, the base insulating film 603, and the amorphous semiconductor film 604 can be formed successively. After that, as illustrated in FIG. 6B, a crystalline semiconductor film which is obtained is etched into a desired shape, crystalline semiconductor films 604a to 604d are formed, and a gate insulating film 605 is formed so as to cover the semiconductor films 604a to 604d. The gate insulating film 605 can be formed in a single layer or stacked layers of a film containing silicone nitride, silicon oxide, silicon oxide containing nitrogen, or silicon nitride containing oxygen, by using a plasma CVD method, a sputtering method, or the like. After the gate insulating film 605 is formed, heat treatment at a temperature of 300 to 450° C. for 1 to 12 hours in an atmosphere containing 3 to 100% of hydrogen may be performed, and a process of hydrogenating the island-shaped crystalline semiconductor films 604a to 604d may be performed. Plasma hydrogenation (using hydrogen excited by plasma) may also be performed as another means of hydrogenation. The crystalline semiconductor films 604a to 604d obtained by irradiating a semiconductor film with continuous-wave (CW) laser light or pulsed laser light oscillated with a repetition rate of 10 MHz or more and scanning the semiconductor film in one direction for crystallization, have a characteristic that the crystal grows in the scanning direction of the light. When a transistor is placed so that the scanning direction is aligned with the channel length direction (the direction in which carriers flow when a channel formation region is formed) and the above gate insulating layer is used in combination, a thin film transistor (TFT) with fewer characteristic variation and high electron field-effect mobility can be obtained. Next, a first conductive film and a second conductive film are stacked over the gate insulating film 605. Here, the first conductive film is formed with a thickness of 20 to 100 nm by a plasma CVD method, a sputtering method or the like, and the second conductive film is formed with a thickness of 100 to 400 nm. The first conductive film and the second conductive film are formed using an element of tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), or the like, or an alloy material or a compound material containing the above element as its main component. Alternatively, the conductive films are formed using a semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus. As examples of a combination of the first conductive film and the second conductive film, a tantalum nitride film and a tungsten film, a tungsten nitride film and a tungsten film, a molybdenum nitride film and a molybdenum film, and the like can be given. Since tungsten and tantalum nitride have high heat resistance, heat treatment for thermal activation can be performed after the first conductive film and the second conductive film are formed. In addition, in the case of a three-layer structure instead of a two-layer structure, a stacked layer structure of a molybdenum film, an aluminum film, and a molybdenum film may be employed. Next, a resist mask is formed by a photolithography method, and etching treatment for forming a gate electrode and a gate line is performed, so that gate electrodes 607 are formed above the semiconductor films 604a to 604d. Next, a resist mask is formed by a photolithography method, and an impurity element imparting n-type conductivity is added at a low concentration into the crystalline semiconductor films 604a to 604d by an ion doping method or an ion implantation method. As the impurity element imparting n-type conductivity, an element which belongs to Group 15, may be used; for example, phosphorus (P) and arsenic (As) are used. Next, an insulating film is formed so as to cover the gate insulating film 605 and the gate electrodes 607. The insulating film is formed in a single layer or stacked layers of a film containing an inorganic material such as silicon, an oxide of silicon, or a nitride of silicon, or an organic material such as an organic resin, by a plasma CVD method, a sputtering method, or the like. Next, the insulating film is selectively etched by anisotropic etching which mainly etch in a vertical direction, so that insulating films 608 (also referred to as sidewalls) which are in contact with side surfaces of the gate electrodes 607 are formed. The insulating films 608 are used as masks for doping when LDD (Lightly Doped Drain) regions are formed later. Next, as illustrated in FIG. 6C, using a resist mask formed by a photolithography method, the gate electrodes 607, and the insulating films 608 as masks, an impurity element imparting n-type conductivity is added into the crystalline semiconductor films 604a to 604d, so that first n-type impurity regions 606a (also referred to as LDD regions), second n-type impurity regions 606b, and channel regions 606c are formed. The concentration of the impurity element contained in the first n-type impurity regions 606a is lower than the concentration of the impurity element contained in the second n-type impurity regions 606b. Next, as illustrated in FIG. 6D, an insulating film is formed in a single layer or stacked layers so as to cover the gate electrodes 607, the insulating films 608, and the like; whereby thin film transistors 630a to 630d are formed. The insulating film is formed in a single layer or stacked layers with an inorganic material such as an oxide of silicon or a nitride of silicon, an organic material such as polyimide, polyamide, benzocyclobutene, acrylic, or epoxy, a siloxane material, or the like, by a CVD method, a sputtering method, an SOG method, a droplet discharging method, a screen printing method, or the like. For example, in the case where the insulating film has a two-layer structure, a silicon nitride oxide film may be formed as a first insulating film 609, and a silicon oxynitride film may be formed as a second insulating film 610. Note that heat treatment for recovering the crystallinity of the semiconductor film, for activating the impurity element which has been added into the semiconductor film, or for hydrogenating the semiconductor film may be performed, before the insulating films 609 and 610 are formed or after one or more of thin films of the insulating films 609 and 610 are formed. For the heat treatment, thermal annealing, a laser annealing method, an RTA method, or the like may be applied. Next, the insulating films 609 and 610, and the like are etched by a photolithography method, and contact holes are formed to expose the second n-type impurity regions 606b. Then, a conductive film is formed so as to fill the contact holes and the conductive film is selectively etched so as to form conductive films 631. Note that silicide may be formed over the surfaces of the semiconductor films 604a to 604d exposed at the contact holes, before the conductive film is formed. The conductive films 631 are formed in a single layer or stacked layers with an element of aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), or silicon (Si), or an alloy material or a compound material containing the above element as its main component, by a CVD method, a sputtering method, or the like. An alloy material containing aluminum as its main component corresponds to a material which contains aluminum as its main component and also contains nickel or an alloy material which contains aluminum as its main component and which also contains nickel and one or both of carbon and silicon, for example. The conductive films 631 preferably employ, for example, a stacked-layer structure of a barrier film, an aluminum-silicon (Al—Si) film, and a barrier film, or a stacked-layer structure of a barrier film, an aluminum-silicon (Al—Si) film, a titanium nitride film, and a barrier film. Note that a barrier film corresponds to a thin film formed using titanium, a nitride of titanium, molybdenum, or a nitride of molybdenum. Aluminum and aluminum silicon which have low resistance and are inexpensive are optimal materials for forming the conductive films 631. In addition, generation of a hillock of aluminum or aluminum silicon can be prevented when upper and lower barrier layers are formed. Further, when the barrier film is formed using titanium that is a highly-reducible element, even if a thin natural oxide film is formed over the crystalline semiconductor film, the natural oxide film is reduced so that preferable contact with the crystalline semiconductor film can be obtained. Next, as illustrated in FIG. 7A, an insulating film 611 is formed so as to cover the conductive films 631, and conductive films 612 are formed over the insulating film 611 so as to be electrically connected to the conductive films 631. The insulating film 611 is formed in a single layer or stacked layers with an inorganic material or an organic material, by a CVD method, a sputtering method, an SOG method, a droplet discharging method, a screen printing method, or the like. The insulating film 611 is preferably formed with a thickness of 0.75 to 3 μm. Further, the conductive films 612 can be formed using any of the materials given in the case of the above conductive films 631. Next, as illustrated in FIG. 7B, conductive films 613 are formed over the conductive films 612. The conductive films 613 are formed using a CVD method, a sputtering method, a droplet discharging method, a screen printing method, or the like with a conductive material. Preferably, the conductive films 613 are formed in a single layer or stacked layers with an element of aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), or gold (Au), or an alloy material or a compound material containing the above element as its main component. Here, a paste containing silver is formed over the conductive films 612 by a screen printing method, and then, heat treatment at a temperature of 50 to 350° C. is performed so as to form the conductive films 613. In addition, after the conductive films 613 are formed over the conductive films 612, regions where the conductive films 613 and the conductive films 612 overlap with each other may be irradiated with laser light so as to improve electrical connection thereof. Note that it is possible to selectively form the conductive films 613 over the conductive films 631 without forming the insulating film 611 and the conductive films 612. Next, as illustrated in FIG. 7C, an insulating film 614 is formed so as to cover the conductive films 612 and 613, and the insulating film 614 is selectively etched by a photolithography method, so that an openings 615 that expose the conductive films 613 is formed. The insulating film 614 is formed in a single layer or stacked layers with an inorganic material or an organic material, by a CVD method, a sputtering method, an SOG method, a droplet discharge method, a screen printing method, or the like. Next, a layer 632 including the thin film transistors 630a to 630d and the like (hereinafter described as a layer 632) is peeled from the substrate 601. As illustrated in FIG. 5A, openings 616 are formed by laser light irradiation (such as UV light), and then, the layer 632 can be peeled from the substrate 601 by using physical force. Alternatively, an etchant may be introduced to the openings 616 before peeling the layer 632 from the substrate 601, so that the peeling layer 602 may be removed. As the etchant, a gas or a liquid containing halogen fluoride or an interhalogen compound is used; for example, chlorine trifluoride (ClF3) is used as a gas containing halogen fluoride. Accordingly, the layer 632 is peeled from the substrate 601. The peeling layer 602 may be partially left instead of being removed entirely. Accordingly, consumption of the etchant can be reduced and process time for removing the peeling layer can be shortened. In addition, the layer 632 can be retained over the substrate 601 even after the peeling layer 602 is removed. In addition, the substrate 601 is preferably reused after the layer 632 is peeled off, in order to reduce the cost. As illustrated in FIG. 8B, after the openings 616 are formed by etching the insulating film by laser light irradiation, a surface of the layer 632 (a surface where the insulating film 614 is exposed) is attached to a first sheet material 617 and the layer 632 can also be peeled completely from the substrate 601. As the first sheet material 617, a thermal peeling tape of which adhesiveness is lowered by heat can be used, for example. Next, as illustrated in FIG. 9A, a second sheet material 618 is provided over the other surface (the surface peeled from the substrate 601) of the layer 632, and one or both heat treatment and pressure treatment are performed to attach the second sheet material 618. Concurrently with or after providing the second sheet material 618, the first sheet material 617 is peeled. As the second sheet material 618, a hot-melt film or the like can be used. When a thermal peeling tape is used as the first sheet material 617, the peeling can be performed by utilizing the heat applied in attaching the second sheet material 618. As the second sheet material 618, a film on which antistatic treatment for preventing static electricity or the like is performed (hereinafter described as an antistatic film) can also be used. As the antistatic film, a film with an antistatic material dispersed in a resin, a film with an antistatic material attached thereon, and the like can be given as examples. The film provided with an antistatic material may be a film with an antistatic material provided over one of its surfaces, or a film with an antistatic material provided over both of its surfaces. Further, as for the film with an antistatic material provided over one of its surfaces, the film may be attached to the layer so that the antistatic material is placed on the inner side of the film or the outer side of the film. The antistatic material may be provided over the entire surface of the film, or over part of the film. As the antistatic material here, a metal, indium tin oxide (ITO), a surfactant such as an amphoteric surfactant, a cationic surfactant, or a nonionic surfactant can be used. In addition to that, as the antistatic material, a resin material containing a cross-linkable copolymer having a carboxyl group and a quaternary ammonium base on its side chain, or the like can be used. By attaching, mixing, or coating a film with such a material to a film, an antistatic film can be formed. By providing the antistatic film, adverse effects on a semiconductor element, when the semiconductor device is dealt with as a commercial product, due to static electricity or the like from outside can be suppressed. Next, as illustrated in FIG. 9B, conductive films 619 are formed so as to cover the openings 615, so that an element group 633 is formed. Note that the conductive films 612 and 613 may be irradiated with laser light so as to improve electrical connection thereof before or after the formation of the conductive films 619. Next, as illustrated in FIG. 10A, the element group 633 is selectively irradiated with laser light so as to be divided into a plurality of element groups. Next, as illustrated in FIG. 10B, the element group 633 is pressure-bonded to a substrate 621 over which a conductive film 622 functioning as an antenna is formed. Specifically, the element group 633 is attached to the substrate 621 so that the conductive film 622 functioning as an antenna formed over the substrate 621 and the conductive film 619 of the element group 633 are electrically connected to each other. Here, the substrate 621 and the element group 633 are bonded to each other by using a resin 623 having adhesiveness. In addition, the conductive film 622 and the conductive film 619 are electrically connected to each other by using a conductive particle 624 contained in the resin 623. By applying the manufacturing method shown in this embodiment mode, a highly reliable semiconductor device without characteristic variation can be manufactured. Note that this embodiment mode can be freely combined with the above embodiment modes. That is, the material or the formation method shown in the above embodiment modes can be used in combination also in this embodiment mode, and the material or the formation method shown in this embodiment mode can be used in combination also in the above embodiment modes. (Embodiment Mode 4) This embodiment mode will describe an example of usage modes of a semiconductor device which is obtained by the manufacturing method shown in the above Embodiment Mode 3. Specifically, applications of a semiconductor device which can input and output data without contact will be described below with reference to the drawings. The semiconductor device which can input and output data without contact is also referred to as an RFID tag, an ID tag, an IC tag, an IC chip, an RF tag, a wireless tag, an electronic tag, or a wireless chip depending on application modes. A semiconductor device 80 has a function of communicating data without contact, and includes a high frequency circuit 81, a power supply circuit 82, a reset circuit 83, a clock generation circuit 84, a data demodulation circuit 85, a data modulation circuit 86, a control circuit 87 for controlling other circuits, a memory circuit 88, and an antenna 89 (FIG. 11A). The high frequency circuit 81 is a circuit which receives a signal from the antenna 89 and also outputs a signal received from the data modulation circuit 86 from the antenna 89. The power supply circuit 82 is a circuit which generates a power supply potential from the received signal. The reset circuit 83 is a circuit which generates a reset signal. The clock generation circuit 84 is a circuit which generates various clock signals based on the received signal input from the antenna 89. The data demodulation circuit 85 is a circuit which demodulates the received signal and outputs the signal to the control circuit 87. The data modulation circuit 86 is a circuit which modulates a signal received from the control circuit 87. As the control circuit 87, a code extraction circuit 91, a code determination circuit 92, a CRC determination circuit 93, and an output unit circuit 94 are formed, for example. The code extraction circuit 91 is a circuit which separately extracts a plurality of codes included in an instruction transmitted to the control circuit 87. The code determination circuit 92 is a circuit which compares the extracted code and a code corresponding to a reference to determine the content of the instruction. The CRC determination circuit 93 is a circuit which detects the presence or absence of a transmission error or the like based on the determined code. Next, an example of operation of the above semiconductor device will be described. First, a radio signal is received by the antenna 89. The radio signal is transmitted to the power supply circuit 82 via the high frequency circuit 81, and a high power supply potential (hereinafter described as VDD) is generated. The VDD is supplied to each circuit included in the semiconductor device 80. In addition, a signal transmitted to the data demodulation circuit 85 via the high frequency circuit 81 is demodulated (hereinafter described as a demodulated signal). The demodulated signal is transmitted to the control circuit 87 through the clock generation circuit 84. Further, a signal transmitted through the reset circuit 83 via the high frequency circuit 81 is also transmitted to the control circuit 87. The signal transmitted to the control circuit 87 is analyzed by the code extraction circuit 91, the code determination circuit 92, the CRC determination circuit 93, and the like. Then, in accordance with the analyzed signal, information of the semiconductor device stored in the storage circuit 88 is output. The output information of the semiconductor device is encoded through the output unit circuit 94. Furthermore, the encoded information of the semiconductor device 80 is, through the data modulation circuit 86, transmitted by the antenna 89 as a radio signal. Note that a low power supply potential (hereinafter described as VSS) is common among a plurality of circuits included in the semiconductor device 80, and VSS can be GND. Thus, data of the semiconductor device can be read by transmitting a signal from a reader/writer to the semiconductor device 80 and receiving the signal transmitted from the semiconductor device 80 by the reader/writer. In addition, the semiconductor device 80 may supply a power supply voltage to each circuit by an electromagnetic wave without a power source (a battery) mounted, or by an electromagnetic wave and a power source (a battery) with the power source (a battery) mounted. A semiconductor device which can be bent can be manufactured by using the manufacturing method shown in Embodiment Mode 3. Therefore, the semiconductor device can be attached to an object having a curved surface. In addition, by applying the manufacturing method shown in Embodiment Mode 3, a highly reliable semiconductor device without characteristic variation can be manufactured. Next, an example of usage modes of a flexible semiconductor device which can input and output data without contact will be described. As illustrated in FIG. 11B, a side face of a portable terminal including a display portion 1110 is provided with a reader/writer 1100. A side face of an article 1120 is provided with a semiconductor device 1130. When the reader/writer 1100 is held over the semiconductor device 1130, information on the article 1120 such as a raw material, the place of origin, an inspection result in each production step, the history of distribution, or an explanation of the article is displayed on the display portion 1110. Further, as illustrated in FIG. 11C, when a product 1160 is transported by a conveyor belt, the product 1160 can be inspected using a reader/writer 1140 and a semiconductor device 1150 attached to the product 1160. Thus, by utilizing the semiconductor device in a system, information can be acquired easily, and improvement in functionality and added value of the system can be achieved. By applying the manufacturing method shown in Embodiment Mode 3, a transistor or the like included in a semiconductor device can be prevented from being damaged even when the semiconductor device fabricated by applying the present invention is attached to an object having a curved surface; thus, a highly reliable semiconductor device can be provided. In addition, as a signal transmission method in the above semiconductor device which can input and output data without contact, an electromagnetic coupling method, an electromagnetic induction method, a microwave method, or the like can be used. The transmission method may be selected as appropriate by a practitioner in consideration of an intended use, and an optimum antenna may be provided in accordance with the transmission method. In the case where, for example, an electromagnetic coupling method or an electromagnetic induction method (for example, 13.56 MHz band) is applied as the signal transmission method in the semiconductor device, electromagnetic induction caused by a change in magnetic field density is used. Therefore, the conductive film functioning as an antenna is formed in an annular shape (for example, a loop antenna) or a spiral shape (for example, a spiral antenna). In the case where a microwave method (for example, UHF band (860 to 960 MHz band), a 2.45 GHz band, or the like) is applied as the signal transmission method in the semiconductor device, the shape such as a length of the conductive film functioning as an antenna may be set as appropriate in consideration of a wavelength of an electromagnetic wave used for signal transmission. FIGS. 12A to 12D illustrate semiconductor devices having antennas with various shapes. These semiconductor devices each have a substrate 1201, an antenna 1202, and an IC chip 1203. When the conductive film functioning as an antenna is formed in a linear shape, for example, a dipole antenna as illustrated in FIG. 12A is obtained. When the conductive film functioning as an antenna is formed in a flat shape, for example, a patch antenna as illustrated in FIG. 12B is obtained. Alternatively, the conductive film functioning as an antenna can be formed in a ribbon-like shape and the like as illustrated in FIGS. 12C and 12D. The shape of the conductive film functioning as an antenna is not limited to a linear shape, and it may be formed in a curved-line shape, a meander shape, or a combination thereof, in consideration of a wavelength of an electromagnetic wave. In whichever shape the conductive film functioning as an antenna is formed, damage to the element group or the like can be prevented by controlling the pressure applied to the element group when the element group is attached to the substrate while monitoring the pressure applied to the element group so that excessive pressure is prevented from being applied. The conductive film functioning as an antenna is formed with a conductive material by using a CVD method, a sputtering method, a printing method such as screen printing or gravure printing, a droplet discharging method, a dispenser method, a plating method, or the like. The conductive film is formed in a single-layer or stacked-layer structure using an element of aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt), nickel (Ni), palladium (Pd), tantalum (Ta), or molybdenum (Mo), or an alloy material or a compound material containing the element as its main component. In the case where a conductive film functioning as an antenna is formed by, for example, a screen printing method, the conductive film can be formed by selectively printing a conductive paste in which conductive particles each having a grain size of several nm to several tens of μm are dissolved or dispersed in an organic resin. As the conductive particle, a fine particle or a dispersive nanoparticle of one or more metals of silver (Ag), gold (Au), copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), tantalum (Ta), molybdenum (Mo), or titanium (Ti); or silver halide can be used. In addition, as the organic resin contained in the conductive paste, one or a plurality of organic resins each functioning as a binder, a solvent, a dispersant, or a coating of the metal particle can be used. Typically, an organic resin such as an epoxy resin or a silicone resin can be used. When forming a conductive film, baking is preferably performed after the conductive paste is applied. For example, in the case where fine particles (of which grain size of 1 nm or more and 100 nm or less inclusive) containing silver as its main component is used as a material of the conductive paste, a conductive film can be obtained by hardening the paste by baking at a temperature of 150 to 300° C. Alternatively, fine particles containing solder or lead-free solder as its main component may be used. In this case, a fine particle having a grain size of 20 μm or less is preferably used. Solder or lead-free solder has an advantage such as low cost. Besides the above materials, ceramic, ferrite, or the like may be applied to an antenna. Furthermore, a material of which dielectric constant and magnetic permeability are negative in a microwave band (metamaterial) can also be applied to an antenna. In the case where an electromagnetic coupling method or an electromagnetic induction method is applied and a semiconductor device including an antenna is placed in contact with a metal, a magnetic material having magnetic permeability is preferably provided between the semiconductor device and the metal. In the case where a semiconductor device including an antenna is provided in contact with a metal, an eddy current flows in the metal accompanying a change in a magnetic field, and a demagnetizing field generated by the eddy current impairs a change in a magnetic field and decreases a communication range. Therefore, an eddy current of the metal and a decrease in the communication range can be suppressed by providing a material having magnetic permeability between the semiconductor device and the metal. Note that ferrite or a metal thin film having high magnetic permeability and little loss of high frequency wave can be used as the magnetic material. Note that an applicable range of the flexible semiconductor device is wide in addition to the above, and the flexible semiconductor device is applicable to any product as long as it is a product whose production, management, or the like can be supported by clarifying information such as the history of an object without contact. For example, the semiconductor device can be mounted on paper money, coins, securities, certificates, bearer bonds, packing containers, books, recording media, personal belongings, vehicles, food, clothing, health products, commodities, medicines, electronic devices, or the like. Examples of them will be described with reference to FIGS. 13A to 13H. The paper money and coins are money distributed to the market, and include one valid in a certain area (cash voucher), memorial coins, and the like. FIG. 13A illustrates the securities, which refer to checks, certificates, promissory notes, and the like. FIG. 13B illustrates the certificates, which refer to driver's licenses, certificates of residence, and the like. FIG. 13C illustrates the bearer bonds, which refer to stamps, rice coupons, various gift certificates, and the like. FIG. 13D illustrates the packing containers, which refer to wrapping paper for lunchboxes and the like, plastic bottles, and the like. FIG. 13E illustrates the books, which refer to hardbacks, paperbacks, and the like. FIG. 13F illustrates the recording media, which refer to DVD software, video tapes, and the like. FIG. 13G illustrates the vehicles, which refer to wheeled vehicles such as bicycles, ships, and the like. FIG. 13H illustrates the personal belongings, which refer to bags, glasses, and the like. The food refers to food articles, drink, and the like. The clothing refers to clothes, footwear, and the like. The health products refer to medical instruments, health instruments, and the like. The commodities refer to furniture, lighting equipment, and the like. The medicines refer to medical products, agricultural chemicals, and the like. The electronic devices refer to liquid crystal display devices, EL display devices, television devices (television receivers, flat-screen TV sets), cellular phones, and the like. Forgery can be prevented by providing the semiconductor device 20 illustrated in FIGS. 13A to 13H to the paper money, the coins, the securities, the certificates, the bearer bonds or the like. Efficiency of an inspection system, a system used in a rental shop, or the like can be improved by providing the semiconductor device 20 to the packing containers, the books, the recording media, the personal belongings, the food, the commodities, the electronic devices, or the like. Forgery or theft can be prevented by providing the semiconductor device 20 to the vehicles, the health products, the medicine, or the like; further, in the case of the medicine, medicine can be prevented from being taken mistakenly. The semiconductor device 20 can be provided to the foregoing article by being attached to the surface or being embedded therein. For example, in the case of a book, the semiconductor device 20 may be embedded in a piece of paper; in the case of a package made from an organic resin, the semiconductor device 20 may be embedded in the organic resin. As described above, efficiency of an inspection system, a system used in a rental shop, or the like can be improved by providing the semiconductor device to the packing containers, the recording media, the personal belonging, the food, the clothing, the commodities, the electronic devices, or the like. In addition, by providing the semiconductor device to the vehicles, forgery or theft can be prevented. Further, by implanting the semiconductor device in a creature such as an animal, an individual creature can be easily identified. For example, by implanting the semiconductor device with a sensor in a creature such as livestock, its health condition such as a current body temperature as well as its birth year, sex, breed, or the like can be easily managed. Note that this embodiment mode can be freely combined with the above embodiment modes. That is, the material or the formation method shown in the above embodiment modes can be used in combination also in this embodiment mode, and the material or the formation method shown in this embodiment mode can be used in combination also in the above embodiment modes. (Embodiment Mode 5) Various electronic devices can be manufactured by incorporating a TFT obtained by implementing the present invention. Specific examples are illustrated in FIGS. 14A to 14F. FIG. 14A illustrates a display device including a housing 1401, a supporter 1402, a display portion 1403, a speaker portion 1404, a video input terminal 1405, and the like. A TFT formed by applying the present invention can be used for a driver IC, the display portion 1403, and the like. The display device includes a liquid crystal display device, a light-emitting display device, and the like, and further includes all the information displaying devices for computers, television reception, advertisement display, and the like. Specifically, a display, a head mount display, a reflection type projector, and the like are given. FIG. 14B illustrates a computer including a housing 1411, a display portion 1412, a keyboard 1413, an external connection port 1414, a pointing device 1415, and the like. A TFT formed by applying the present invention is applicable not only to a pixel portion of the display portion 1412 but also to a semiconductor device such as a driver IC for display, a CPU inside a main body, or a memory. FIG. 14C illustrates a cellular phone, as a typical example of mobile information processing terminals. This cellular phone includes a housing 1421, a display portion 1422, an operation key 1423, and the like. A TFT formed by applying the present invention is applicable not only to a pixel portion of the display portion 1422 but also to a driver IC for display, a memory, an audio processing circuit, or the like. In addition to the above cellular phone, a TFT formed by applying the present invention can be used for an electronic device such as a PDA (Personal Digital Assistant, information mobile terminal), a digital camera, or a compact game machine. For example, it is possible to apply the TFT of the present invention to a functional circuit such as a CPU, a memory, or a sensor, or to a pixel portion of such an electronic device or a driver IC for display. FIGS. 14D and 14E illustrate a digital camera. FIG. 14E illustrates a rear side of the digital camera illustrated in FIG. 14D. This digital camera includes a housing 1431, a display portion 1432, a lens 1433, an operation key 1434, a shutter button 1435, and the like. A TFT formed by applying the present invention is applicable to a pixel portion of the display portion 1432, a driver IC for driving the display portion 1432, a memory, or the like. FIG. 14F illustrates a digital video camera including a main body 1441, a display portion 1442, a housing 1443, an external connection port 1444, a remote control receiving portion 1445, an image receiving portion 1446, a battery 1447, an audio input portion 1448, an operation key 1449, an eyepiece portion 1450, and the like. A TFT formed by applying the present invention is applicable to a pixel portion of the display portion 1442, a driver IC for controlling the display portion 1442, a memory, a digital input processing device, a sensor portion, or the like. Besides, a TFT formed by applying the present invention can be used for a navigation system, an audio reproducing device, an image reproducing device equipped with a recording medium, or the like. TFTs formed by applying the present invention can be used for pixel portions of display portions of these devices, driver ICs for controlling the display portions, memories, digital input processing devices, sensor portions, or the like. As thus described, the application range of a TFT manufactured by applying the present invention is extremely wide, and the TFT manufactured by applying the present invention can be used for electronic devices of every field. Note that the display devices used in the electronic devices can employ not only glass substrates but also heat-resistant substrates formed with a synthetic resin, in accordance with the size, strength, and intended purpose. Accordingly, further reduction in weight can be achieved. The present application is based on Japanese Patent Application serial no. 2006-271363 filed in Japan Patent Office on Oct. 3, 2006, the entire contents of which are hereby incorporated by reference.
	abstract	The invention relates to a displacement-detecting element (1) comprising a measuring resistance (2), voltage source (3) and a displacement-dependent voltage pick off (4). The measuring resistance (2) is embodied in the form of a strip. The length of the resistor (6) corresponds to at least the maximal length of displacement (7) of the component to be detected. The invention also relates to a multileaf collimator (23) having such a displacement-detecting element (1). The aim of the invention is to produce a displacement-detecting element (a) for detecting the position of the leaves (22) in a multileaf collimator (23) in a precise and faultless manner. The displacement detecting element (1) is designed for detecting the displacement (7xe2x80x2) of the leaves (22) in a multileaf collimator (23) in the following manner: the measuring resistance (2) or the voltage pick off point (4) are connected in a rigid manner to the leaves (22) in order to detect the displacement and another functioning element (4 or 2) is arranged in a fixed manner. At least one of these functioning elements (2, 4) is disposed in an area (33, 33xe2x80x2, 33xe2x80x3) of the leaves (22), which is not exposed to main radiation (34).
	abstract	An object of this invention is to provide an electron beam lithography system capable of rapidly creating an accurate exposure map for proximity effect correction. The inventive system creates the map by dividing shot figures by mesh and adding up the divided area values for each mesh. The system comprises: (1) a function for judging and dividing boundaries of shots to be rendered based on mesh positions as well as shot positions and figures in the map, and (2) a function for calculating divided shot area values and adding the values simultaneously to adjacent addresses in cumulative fashion in a plurality of memories furnished downstream of the system.
052182096	claims	1. An ion implanter for implanting ions into a batch of semiconductor wafers, comprising: a centrifugal type wafer holding disk having a conically curved peripheral portion; a plurality of wafer rests aligned along the peripheral portion of said wafer holding disk, wherein the bottom holding surfaces of said wafer rests are curved nearly in the shape of said conically curved peripheral portion of said wafer holding disk. a plurality of wafer rests aligned around the periphery of the semiconductor wafer holding disk, each wafer rest having a bottom holding surface which is conically curved. a centrifugal type wafer holding disk having a conically curved peripheral portion; a plurality of wafer rests aligned around said peripheral portion of said wafer holding disk, said wafer rests having a bottom holding surface which is a fragment of a conical surface having the same axis and slope as said conically curved peripheral portion of said wafer holding disk. 2. The ion implanter of claim 1, wherein said plurality of wafer rests each have a diameter of at least 150 mm. 3. A semiconductor wafer holding disk for an ion implanter, comprising: 4. An ion implanter for implanting ions into a batch of semiconductor wafers, comprising:
052689395	claims	1. A control system comprising: a nuclear reactor operable for heating water to generate main steam under pressure, and disposed in flow communication with a steam turbine by a main steamline for discharging thereto said main steam; a plurality of flow control valves disposed in parallel flow communication in said steamline for controlling flow of said main steam from said reactor to said turbine; a bypass valve disposed in flow communication with said steamline upstream of said control valves and with a condenser of said turbine for selectively bypassing a portion of said main steam as bypass steam around said control valves and turbine to said condenser; a pressure regulator operatively joined to said control valves and said bypass valve for controlling flow of said main steam to said turbine; a turbine controller operatively joined to said control valves and said bypass valve for controlling flow of said main steam to said turbine in conjunction with said pressure regulator; and means for automatically detecting failure of one of said control valves which passes steamflow therethrough at a flowrate below a control valve (CV) flow demand therefor, said failure detecting means being operatively joined to said bypass valve and being effective for opening said bypass valve upon detecting said control valve failure. a first low value selector operatively joined between said pressure regulator and said turbine controller for receiving a total flow (TF) demand from said pressure regulator and a load demand from said turbine controller, and for selecting the lesser thereof as said CV flow demand for controlling flowrate of said control valves; a first limiter operatively joined between said pressure regulator and said first selector for providing a predetermined limit to said TF demand; a second low value selector operatively joined between said first selector and said failure detecting means for receiving said CV flow demand from said first selector and an actual turbine flow signal from sid failure detecting means, and for selecting the lesser thereof as a bypass reference; and a bypass comparator operatively joined to said first limiter, said second selector, and said bypass valve for obtaining a difference between said TF demand and said bypass reference as a bypass demand, said bypass demand being provided to said bypass valve for controlling operation thereof. a CV controller operatively joined to said first limiter for receiving therefrom said CV demand, and operatively joined to said control valve for controlling opening thereof; a position sensor for providing a CV actual position signal of said control valve; and wherein said failure detection means are operatively joined to said first selector for receiving therefrom said CV demand, and operatively joined to said position sensor for receiving therefrom said CV actual position signal, and effective for comparing said CV demand and said CV actual position signal to detect said CV failure based on a predetermined difference therebetween, and, upon detecting said control valve failure, are effective for generating said actual turbine flow signal based upon said CV actual position signals for said plurality of control valves. wherein said failure detecting means are operatively joined to said pressure sensor for receiving therefrom said pressure signal, and are effective for comparing said pressure signal with a predetermined reference value thereof to detect said control valve failure based on a predetermined difference therebetween, and, upon detecting said control valve failure, are effective for generating said actual turbine flow signal based upon said pressure signal. wherein said failure detecting means are operatively joined to said power sensor for receiving therefrom said electrical power signal, and are effective for comparing said power signal with a predetermined reference value thereof to detect said control valve failure based on a predetermined difference therebetween, and, upon detecting said control valve failure, are effective for generating said actual turbine flow signal based upon said electrical power signal. wherein said failure detecting means are operatively joined to said flow sensors for receiving therefrom said flow signals, and are effective for comparing said flow signals with predetermined reference values thereof to detect said control valve failure based on a predetermined difference therebetween, respectively, and, upon detecting said control valve failure, are effective for generating said actual turbine flow signal based upon said flow signals. wherein said failure detecting means are operatively joined to said RFCS, and are effective for reducing said reactor recirculation flow for reducing said main steamflow through said steamline upon detecting said control valve failure. automatically detecting failure of one of said control valves which passes steamflow therethrough at a flowrate below a demand flowrate provided by one of said pressure regulator and said turbine controller; and automatically opening said bypass valve upon detecting said control valve failure. 2. A system according to claim 1 further comprising: 3. A system according to claim 2 further comprising for each of said control valves: 4. A system according to claim 2 further comprising a pressure sensor joined to said turbine for providing a pressure signal for said main steam inside said turbine; and 5. A system according to claim 2 further comprising an electrical power sensor joined to said generator for providing an electrical power signal from said generator; and 6. A system according to claim 2 further comprising a plurality of flow sensors each joined in serial flow communication between a respective one of said control valves and said turbine for providing an actual flow signal for said main steamflow through said control valves; and 7. A system according to claim 6 further including a recirculation flow control system (RFCS) operatively joined to said reactor for selectively varying recirculation flow of said water in said reactor for controlling flowrate of said main steam therefrom; 8. A system according to claim 6 further including a control rod positionable in said reactor by a control rod drive and controlled by a rod control system, and said failure detection means are operatively joined to said rod control system and effective for inserting said control rod into said reactor for reducing power to reduce said main steamflow. 9. A system according to claim 8 wherein said failure detecting means are effective for providing a reduction demand to said RFCS for reducing said main steamflow from said reactor in a reduction value attributed to a maximum, normal contribution of a single one of said control valves. 10. A method of operating a nuclear reactor joined in flow communication with a steam turbine by a main steamline having a plurality of control valves for controlling main steamflow to said turbine, and bypass valve for selectively bypassing a portion of said main steamflow around said control valves and said turbine to a condenser, said control valves and bypass valve being controlled by a pressure regulator and a turbine controller; said method including the steps of: 11. A method according to claim 10 further including the step of automatically reducing power in said reactor to reduce said main steamflow to cause said open bypass valve to close.
048266540	claims	1. A fuel assembly comprising a plurality of fuel rods, moderator rods disposed among said fuel rods, upper and lower tie plates for holding both end portions of each of said fuel rods and said moderator rods and fuel spacers for keeping spaces between said fuel rods and said moderator rods as wide as a predetermined width, the improvement wherein there is provided a space region substantially void of any solid, extending in an axial direction from said lower tie plate to said upper tie plate and having a space sufficient to disposed at least one of said fuel rods therein, at least one of said moderator rods being disposed immediately adjacent to said space region for delimiting a boundary of said space region in a direction transverse to the axial direction, said upper and lower tie plates delimiting a boundary of said space region in the axial direction, and said fuel rods, said moderator rods and said space region being disposed in a grid form, said space region having substantially the same cross-sectional area from an upper end portion thereof proximate to said upper tie plate to a lower end portion thereof proximate to said lower tie plate. 2. A fuel assembly as defined in claim 1, wherein said moderator rod is a water rod. 3. A fue1 assembly as defined in claim 1, wherein said space region is disposed in a central portion of a bundle of said fuel rods and said water rods. 4. A fuel assembly as defined in claim 3, wherein wherein said space region corresponds to a unit cell which which has a space as wide as one of said fuel rods and said moderator rods being positioned to surround said space region. 5. A fuel assembly as defined in claim 4, wherein said space region is encompassed by eight of said water rods so as to face directly said eight water rods. 6. A fuel assembly as defined in claim 4, wherein said space region is encompassed by four pairs of said water rods so as to face directly one of each said pair of water rods, and each of said pairs of water rods are arranged radially. 7. A fuel assembly as defined in claim 3, wherein said space region corresponds to five unit cells each of which has a space as wide as one of said fuel rods, said moderator rods being disposed to surround said space region. 8. A fuel assembly comprising: a channel box axially elongated; a plurality of fuel rods disposed in said channel box; a plurality of moderator rods disposed among said fuel rods; upper and lower tie plates holding both end portions of said fuel rods and said moderator rods, respectively; fuel spacers for keeping spaces between said fuel rods and said moderator rods as wide as a predetermined width; a space region substantially void of any solid positioned at a central portion of said channel box, said space region extending in the axial direction from said lower tie plate to said upper tie plate so as to be delimited in the axial direction by said lower and upper tie plates, and a space size of said space region being such that at least one of said fuel rods can be disposed therein; wherein at least four of said moderator rods are disposed immediately adjacent to said space region so that each of said four moderator rods faces said space region and for a boundary of said space region in a direction transverse to the axial direction; and wherein said space region has substantially the same cross-sectional area along the axial direction from an upper end portion thereof to a lower end portion thereof. a channel box axially elongated; a plurality of fuel rods disposed in said channel box; a plurality of moderator rods disposed among said fuel rods; upper and lower tie plates holding both end portions of said fuel rods and said moderator rods, respectively; fuel spacers for keeping spaces between said fuel rods and said moderator rods as wide as a predetermined width; means for delimiting a space region substantially void of any solid at a predetermined portion of said channel box and a size sufficient to enable at least one of said fuel rods to be disposed therein, said means delimiting said space region in the axial direction of said channel box including said upper and lower tie plates and in a direction transverse to the axial direction including at least one moderator rod disposed immediately adjacent to said space region so that said at least one moderator rod faces said space region and forms a part of a boundary of said space region; and wherein said space region has substantially the same cross-sectional area from an upper end portion thereof to a lower end portion thereof in the axial direction of said channel box. 9. A fuel assembly as defined in claim 8, wherein each of said moderator rods is a water rod and said water rods are arranged symmetrically with respect to said space region. 10. A fuel assembly comprising: 11. A fuel assembly as defined in claim 10, wherein said predetermined portion of said channel box is a central portion of said channel box in the transverse direction, and at least four of said moderator rods are disposed immediately adjacent to said space region so that each of said four moderator rods faces said space region and forms a part of a boundary thereof. 12. A fuel assembly as defined in claim 11, wherein each of said moderator rods is a water rod and said water rods are arranged symmetrically with respect to said space region. 13. A fuel assembly as defined in claim 10, wherein said space region region is adapted to be filled with water when said fuel assembly is loaded in a core of a nuclear reactor.
	claims	1. A method of producing radionuclides, which includesin an irradiation zone, irradiating a target medium comprising at least a target nuclide material, with neutron irradiation, thereby causing radionuclides to form in the target nuclide material, with at least some of the formed radionuclides being ejected from the target nuclide material;capturing and collecting the ejected radionuclides in a recoil capture material which is selected from amorphous carbon, carbon allotropes and mixtures thereof, the amorphous carbon and/or carbon allotropes not having an empty cage structure at crystallographic level, with the ejected radionuclides thereby being concentrated or enriched in the recoil capture material relative to cold nuclei; andrecovering the captured radionuclides from the recoil capture material. 2. The method according to claim 1, wherein the target nuclide material is selected from the group consisting of a pure metal and a metal compound. 3. The method according to claim 2, wherein the metal of the target nuclide material is selected from the group of metal elements in the Periodic Table of Elements extending from scandium, of atomic number 21, to bismuth, of atomic number 83, both elements included, with the non-metal elements arsenic, selenium, bromine, krypton, tellurium, iodine and xenon thus being excluded, 4. The method according to claim 3, wherein the metal of the target nuclide material is tin. 5. The method according to claim 1, wherein the target nuclide material and the recoil capture material are both in finely divided particulate form, each having a mean particle size of at most about 50 nm. 6. The method according to claim 5, which includes mixing the target nuclide material and the recoil capture material, with the target medium thus comprising both target nuclide material and recoil capture material. 7. The method according to claim 1, wherein irradiating the target medium includes placing the target medium in the path of a neutron flux from a neutron source. 8. The method according to claim 1, in which recovering the captured radionuclides from the recoil capture material includes treating the recoil capture material with a dilute and/or a concentrated acidic extraction solvent, thereby to form a recoil capture material suspension, and chemically extracting or leaching captured radionuclides from the recoil capture material, to obtain a radionuclide-enriched extraction solvent. 9. The method according to claim 8, which includes incubating the recoil capture material suspension for a period which does not exceed the half-life of the captured radionuclides. 10. The method according to claim 8, which includes recovering or separating radionuclide-enriched extraction solvent from the recoil capture material by means of centrifugation, vortex separation and/or filtration. 11. The method according to claim 1, which includes recovering the captured radionuclides from the recoil capture material by treating the recoil capture material with an alkaline extraction solvent. 12. The method according to claim 1, which includes recovering the captured radionuclides from the recoil capture material by combusting the recoil capture material in oxygen. 13. The method according to claim 8, in which the target medium comprises a mixture of the recoil capture material and the target nuclide material and the method includes separating the recoil capture material from the target nuclide material before recovering radionuclides from the recoil capture material. 14. The method according to claim 13, wherein separating the recoil capture material from the target nuclide material is achieved by means of liquid-liquid extraction, using an aqueous liquid and an organic liquid as liquid-liquid extraction solvents.
	claims	1. A method for collimating a radiation beam, wherein the beam travels along a beamline, the method comprising subjecting the beam to an aperture in a collimator, wherein the aperture is continuous throughout the length of the collimator and the collimator has no moving parts. 2. The method as recited in claim 1 wherein the aperture is integrally molded with a monolith that yaws and pitches relative to but independent of the beamline. 3. The method as recited in claim 2 wherein the dimensions of the collimator are formed when two substrates are joined to form the monolith. 4. The method as recited in claim 3 wherein the substrates are integrally molded to each other. 5. The method as recited in claim 3 wherein the substrates are reversibly joined to each other. 6. The method as recited in claim 2 wherein collimation of the beam occurs when the monolith yaws, or pitches, or yaws and pitches relative to the beamline. 7. The method as recited in claim 1 wherein the collimator defines an input surface residing in a plane that extends in a direction that is perpendicular to the beamline, and the surface is positioned relative to the beamline until a predetermined collimator configuration is achieved. 8. A system for collimating radiation beams, the system comprising:a. a collimator body; andb. a stage for pitching or yawing or pitching and yawing the body, wherein the stage moves independently of the radiation beams. 9. The system as recited in claim 8 wherein the collimator body comprises no moving parts. 10. The system as recited in claim 8 wherein the collimator body defines a plurality of apertures adapted to receive the radiation beams. 11. The system as recited in claim 8 wherein the collimator body is comprised of a thermally conducting material selected from the group consisting of metal matrix composite alloys, tungsten, copper, copper composite, aluminum oxide ceramics, and combinations thereof. 12. The system as recited in claim 8 wherein the collimator body is fabricated from at least two substrates joined together. 13. The system as recited in claim 8 wherein the collimator body is fabricated from at least two substrates and the substrates are integrally molded to each other. 14. The system as recited in claim 8 wherein the collimator body is fabricated from at least two substrates and the substrates are reversibly joined to each other. 15. A system for collimating a medium, the system comprising:a. a collimator body; andb. a body support surface for pitching or yawing or pitching and yawing the body, wherein the body support surface moves independently of the medium. 16. The system as recited in claim 15 wherein the collimator body is fabricated from material having a yield strength to withstand the medium it is collimating. 17. The system as recited in claim 16 wherein the medium is a neutron beam and the material is plastic. 18. The system as recited in claim 16 wherein the medium is high energy radiation and the material is comprised of a thermally conducting material selected from the group consisting of metal matrix composite alloys, tungsten, copper, copper composite, aluminum oxide ceramics, and combinations thereof.
	description	This patent document claims the benefits and priorities of U.S. Provisional Application No. 61/528,573, filed on Aug. 29, 2011, and U.S. Provisional Application No. 61/429,681, filed on Jan. 4, 2011, which are hereby incorporated by reference. The United States Government has rights in this invention pursuant to Contract No. DE-AC52-07NA27344 between the United States Department of Energy and Lawrence Livermore National Security, LLC for the operation of Lawrence Livermore National Laboratory. This patent document generally relates to particle accelerators, including linear particle accelerators that use dielectric wall accelerators. Particle accelerators are used to increase the energy of electrically-charged atomic particles, e.g., electrons, protons, or charged atomic nuclei. High energy electrically-charged atomic particles are accelerated to collide with target atoms, and the resulting products are observed with a detector. At very high energies the charged particles can break up the nuclei of the target atoms or molecules and interact with other particles. Transformations are produced that help to discern the nature and behavior of fundamental units of matter. Particle accelerators are also important tools in the effort to develop nuclear fusion devices, as well as in medical applications such as proton therapy for cancer treatment. Proton therapy uses a beam of protons to irradiate diseased tissue, most often in the treatment of cancer. The proton beams can be utilized to more accurately localize the radiation dosage and provide better targeted penetration inside the human body when compared with other types of external beam radiotherapy. Due to their relatively large mass, protons have relatively small lateral side scatter in the tissue, which allows the proton beam to stay focused on the tumor with only low-dose side-effects to the surrounding tissue. The radiation dose delivered by the proton beam to the tissue is at or near maximum just over the last few millimeters of the particle's range, known as the Bragg peak. Tumors closer to the surface of the body are treated using protons with lower energy. To treat tumors at greater depths, the proton accelerator must produce a beam with higher energy. By adjusting the energy of the protons during radiation treatment, the cell damage due to the proton beam is maximized within the tumor itself, while tissues that are closer to the body surface than the tumor, and tissues that are located deeper within the body than the tumor, receive reduced or negligible radiation. Proton beam therapy systems are traditionally constructed using large accelerators that are expensive to build and hard to maintain. However, recent developments in accelerator technology are paving the way for reducing the footprint of the proton beam therapy systems that can be housed in a single treatment room. Such systems often require newly designed, or re-designed, subsystems that can successfully operate within the small footprint of the proton therapy system, reduce or eliminate health risks for patients and operators of the system, and provide enhanced functionalities and features. The technology described in this patent document includes devices, systems and methods for varying beam spot size of a charged particle beam in particle accelerators, including linear particle accelerators that use dielectric wall accelerators. In one implementation, a charged particle accelerator system is provided to include a dielectric wall accelerator (DWA) including a high gradient lens section that transports a charged particle beam and controls a beam spot size of the charged particle beam, and a main DWA section that accelerates the charged particle beam. The high gradient lens section and the main DWA section include a series of alternating layers of insulators and conductors with a hollow center, the series of alternating layers stacked together to form a single high gradient insulator (HGI) tube to allow propagation of the charged particle beam through the hollow center of the HGI tube. The DWA includes a plurality of transmission lines connected to the high gradient lens section; a plurality of transmission lines connected to the main DWA section and one or more voltage sources configured to supply an adjustable voltage value to each transmission line of the plurality of transmission lines connected to the high gradient lens section and the main DWA section. In another implementation, a method of shaping a charged particle beam is provided to include establishing a desired electric field across a plurality of sections of a dielectric wall accelerator (DWA). The DWA includes a high gradient lens section and a main DWA section. The high gradient lens section and the main DWA section include a series of alternating layers of insulators and conductors with a hollow center, the series of alternating layers stacked together to form a single high gradient insulator (HGI) tube to allow propagation of a charged particle beam through the hollow center of the HGI tube. The DWA includes a plurality of transmission lines connected to the high gradient lens section, a plurality of transmission lines connected to the main DWA section, and one or more voltage sources configured to supply an adjustable voltage value to each transmission line of the plurality of transmission lines connected to the high gradient lens section and the main dielectric wall section. The method includes directing the charged particle beam through the DWA. In yet another implementation, a method is provided for treatment of a patient using a charged particle accelerator system. This method includes irradiating one or more target areas within the patient's body with a charged particle beam that is output from the charged particle beam accelerator system. The charged particle accelerator system includes a charged particle source and a dielectric wall accelerator (DWA). The DWA includes a high gradient lens section and a main DWA section. The high gradient lens section and the main DWA section include a series of alternating layers of insulators and conductors with a hollow center, the series of alternating layers are stacked together to form a single high gradient insulator (HGI) tube to allow propagation of a charged particle beam through the hollow center of the HGI tube. The DWA includes a plurality of transmission lines connected to the high gradient lens section, a plurality of transmission lines connected to the main DWA section, and one or more voltage sources configured to supply an adjustable voltage value to each transmission line of the plurality of transmission lines connected to the high gradient lens section and the main dielectric wall section. The charged particle accelerator system further includes a timing and control component configured to produce timing and control signals to the charged particle source, the high gradient lens and the dielectric wall accelerator. The disclosed method includes adjusting the one or more voltage sources to supply a first set of voltage values to the high gradient lens section and the main DWA section to produce an output charged particle beam with a particular set of baseline characteristics. These and other implementations and various features and operations are described in greater detail in the drawings, the description and the claims. The devices, systems and methods and their implementations disclosed in this patent document provide mechanisms to vary spot sizes of charged particle beams in dielectric wall accelerators. This capability of varying beam spot sizes of charged particle beams rapidly and dynamically can be advantageous in various applications, including, for example, increasing the effectiveness of radiation therapy. In implementations, the output charged particle beam of the dielectric wall accelerators, e.g., proton or electron beams, can use the varying beam spot sizes to achieve desired focusing and defocusing of the charged particle beam at a target. FIG. 1 illustrates a simplified diagram of a linear particle accelerator (linac) 100 that can accommodate the disclosed embodiments. For simplicity, FIG. 1 only depicts some of the components of the linac 100. Therefore, it is understood that the linac 100 can include additional components that are not specifically shown in FIG. 1. It should also be noted that while some of the disclosed embodiments are described in the context of the exemplary linear accelerator 100 of FIG. 1, it is understood that the disclosed embodiments can be used in other systems and in conjunction with other applications that can benefit from a modified dielectric wall accelerator that enables dynamic modifications of a charged particle beam. Referring back to FIG. 1, a charged particle source, such as exemplary ion source 102, produces a charged particle beam that is coupled to a radio frequency quadrupole (RFQ) 106 using coupling components 104. The coupling components 104 can, for example, include components such as one or more Einzel lenses that provide a focusing/defocusing mechanism for the charged particle beam that is input to the RFQ 106. The RFQ 106 provides focusing, bunching and acceleration for the charged particle beam. One exemplary configuration of a radio frequency quadrupole includes an arrangement of four triangular-shaped vanes that form a small hole, through which the proton beam passes. The edges of the vanes at the central hole include ripples that provide acceleration and shaping of the beam. The vanes are RF excited to accelerate and shape the ion beam passing therethrough. In the specific example in FIG. 1, the charged particle beam output by RFQ 106 is coupled to a modified dielectric wall accelerator (MDWA) 108 in accordance with the disclosed embodiments of the described technology. The MDWA 108 further accelerates the beam to produce an output charged particle beam, shown as an exemplary proton beam 110. The MDWA 108 can also dynamically shape the charged particle beam so as to provide focusing, defocusing, spot size variations, and other modifications to the charged particle beam. The output charged particle beam (e.g., the proton beam 110) is delivered to the target 114, such as a tumor within a patient's body in cancer therapy applications. FIG. 1 also shows Blumlein devices 112 that are used to deliver voltage pulses to the MDWA 108. The timing and control components 116 provide the necessary timing and control signals to the various components of the linac 100 to ensure proper operation and synchronization of those components. For example, the timing and control components 116 can be used to control the timing and value of voltages that are applied to the MDWA 108. As will be described in the sections that follow, the control and timing components 116 can provide different timing and voltage control signals for application to different sections of the MDWA 108. FIG. 2A, FIG. 2B, FIG. 2C and FIG. 2D provide exemplary diagrams that illustrate the structure and operation of a single DWA cell 10 that can be utilized with the linac 100 of FIG. 1. FIGS. 2A-2C provide a time-series that is related to the state of a switch 12. As shown in FIGS. 2A-2C, a sleeve 28 fabricated from a dielectric material is molded or otherwise formed on the inner diameter of the single accelerator cell 10 to provide a dielectric wall of an acceleration tube. FIG. 2D shows an example of the dielectric sleeve 28 of the DWA in a high gradient insulator (HGI) structure, which is a layered insulator 30 having alternating electrically conductive materials (e.g., metal conductors) and dielectric materials. The HGI structure 30 in this example is made of alternating dielectric and conductive disk layers to form a HGI tube with a hollow center 40 for transporting the charged particles. This HGI structure is capable of withstanding high voltages generated by the Blumlein devices and, therefore, provides a suitable dielectric wall of the accelerator tube. The charged particle beam is introduced at one end of the accelerator tube for acceleration along the central axis of the HGI tube. As shown in FIGS. 2A, 2B and 2C, the switch 12 and conductive transmission lines 16, 14 and 18 are connected to the HGI tube 28 to allow the middle transmission line 14 to be charged by a high voltage source. The conductive transmission lines 16, 14 and 18 are shown as conductive rings or plates in this specific example, but can be alternatively implemented in various transmission line geometries other than the rings or plates. Each of the conductive transmission lines 16, 14 and 18 is in electrical contact with a respective conductive layer of the alternating conductive and dielectric layers in the HGI tube 28. A laminated dielectric 20 with a relatively high dielectric constant separates the conductive plates 14 and 16 and forms the top half of the DWA cell 10 with the conductive plates 14 and 16. A laminated dielectric 22 with a relatively low dielectric constant separates the conductive plates 14 and 18 and forms the bottom half of the DWA cell 10 with the conductive plates 14 and 18. In the exemplary diagram of FIGS. 2A-2C, the middle conductive plate 14 is set closer in distance to the bottom conductive plate 18 than to the top conductive plate 16, such that the combination of the different spacing and the different dielectric constants results in the same characteristic impedance on both sides of the middle conductive plate 14. Although the characteristic impedance may be the same on both halves, the propagation velocity of signals through each half is not the same. The propagation velocity of an applied signal in the higher dielectric constant half with laminated dielectric 20 is slower. This difference in relative propagation velocities is represented by a short fat arrow 24 and a long thin arrow 25 in FIG. 2B, and by a long fat arrow 26 and a reflected short thin arrow 27 in FIG. 2C. In some systems, the Blumleins comprise a linear-folded arrangement with the same dielectric on both halves and different lengths from switch to gap. In a first position of the switch 12, as shown in FIG. 2A, both halves are oppositely charged so that there is no net voltage along the inner length of the assembly. After the lines have been fully charged, the switch 12 closes across the outside of both lines at the outer diameter of the single accelerator cell, as shown in FIG. 2B. This causes an inward propagation of the voltage waves 24 and 25 which carry opposite polarity to the original charge such that a zero net voltage will be left behind in the wake of each wave. When the fast wave 25 hits the inner diameter of its line, it reflects back from the open circuit it encounters. Such reflection doubles the voltage amplitude of the wave 25 and causes the polarity of the fast line to reverse. For only an instant moment more, the voltage on the slow line at the inner diameter will still be at the original charge level and polarity. As such, after the wave 25 arrives but before the wave 24 arrives at the inner diameter, the field voltages on the inner ends of both lines are oriented in the same direction and add to one another, as shown in FIG. 2B. Such adding of fields produces an impulse field that can be used to accelerate a beam. The impulse field is neutralized, however, when the slow wave 24 eventually arrives at the inner diameter, and is reflected. This reflection of the slow wave 24 reverses the polarity of the slow line, as is illustrated in FIG. 2C. The time that the impulse field exists can be extended by increasing the distance that the voltage waves 24 and 25 must traverse. One way is to simply increase the outside diameter of the single accelerator cell. Another, more compact way is to replace the solid discs of the conductive plates 14, 16 and 18 with one or more spiral conductors that are connected between conductor rings at the inner and/or outer diameters. Multiple DWA cells 10 may be stacked or otherwise arranged over a continuous dielectric wall, to accelerate the proton beam using various acceleration methods. For example, multiple DWA cells may be stacked and configured to produce together a single voltage pulse for single-stage acceleration. In another example, multiple DWA cells may be sequentially arranged and configured for multi-stage acceleration, wherein the DWA cells independently and sequentially generate an appropriate voltage pulse. For such multi-stage DWA systems, by appropriately timing the closing of the switches (as illustrated in FIGS. 2A to 2C), the generated electric field on the dielectric wall can be made to move at any desired speed. In particular, such a movement of the electric field can be made synchronous with the charged particle beam pulse that is input to the DWA, thereby accelerating the charged particle beam in a controlled fashion that resembles a traveling wave propagating down the DWA axis. The charged particle beam that travels within the DWA in the above fashion is sometimes referred to a “virtual traveling wave.” To attain the highest accelerating gradient in the DWA, the accelerating voltage pulses that are applied to consecutive sections of the DWA should have the shortest possible duration since the DWA can withstand larger fields for pulses with narrow durations. This can be done by appropriately timing the switches in the transmission lines that feed the continuous HGI tube of the DWA. The short accelerating voltage pulses tend to have little or no flattop, which can lead to undesirable charged particle beam spot size and emittance growth. In the middle of the DWA, at the time when a particular section of the DWA is charged to accelerate the particle beam bunch, the high gradient insulator sections immediately before and after the charged section are also at least partially charged, and the corresponding charged particle beam is at least partially excited, due to the finite traveling speed of the charged particle bunch and the non-zero voltage pulse width that is applied to the DWA section. At the two ends of the DWA, however, only one of the upstream or the downstream sections of the HGI/associated charged particle bunch is charged/excited depending on whether the charged particle beam is at the entrance or exit of the DWA, respectively. Therefore, assuming that the characteristic length for an excited section of the HGI is L, the length of the excited HGI section at the two ends of the DWA is shorter than L, and the virtual traveling wave buckets (i.e., the accelerating fields that move the charged particle beam down the DWA) at the entrance and exit of the DWA are generally much shorter compared to the wave buckets in the middle of the DWA. To facilitate the understanding of the disclosed embodiments, it is instructive to analyze the longitudinal electric field along the z-axis (e.g., the direction in which the charged particle beam is traveling) as a function of time, t, as give by Equation (1) below. E z ⁡ ( z , t ) = E ~ ⁡ ( z ) ⁢ f ⁡ ( t - ∫ z ⁢ ⁢ 0 z ⁢ ⁢ ⅆ z ′ v ) . ( 1 ) In Equation (1), {tilde over (E)}(z) is the field gradient of the electric field and f ⁡ ( t - ∫ z ⁢ ⁢ 0 z ⁢ ⁢ ⅆ z ′ v ) describes the electric field's waveform and its field package moving down the z-axis with velocity, ν. With ∇·{right arrow over (E)}=0, the corresponding radial electric field at a radial position, r, within the HGI tube, is much less than E z  ∂ E z ∂ z  ,is given by Equation (2). E r ⁡ ( z , t ) ≈ - r 2 ⁢ ∂ E z ⁡ ( z , t ) ∂ z . ( 2 ) Combining Equations (1) and (2) produces the following expression for the radial electric field. E r ⁡ ( z , t ) ≈ - r 2 ⁡ [ E ′ ~ ⁡ ( z ) ⁢ f ⁡ ( z - vt ) + E ~ ⁡ ( z ) ⁢ ⅆ f ⅆ t / v ] . ( 3 ) In Equation (3), the term {tilde over (E)}′(z), represents the derivative of {tilde over (E)}(z) with respect to z. It should be further noted that in order to facilitate the understanding of the disclosed embodiments, Equations (2) to (4) have been presented to include a radial electric field based on the simplifying assumption that the transverse electric field is radially symmetric. However, the disclosed embodiments are also applicable to transverse electric fields that are not radially symmetric. In those cases, the transverse electric field computations can be carried out using the x- and the y-components. If the traveling field's gradient {tilde over (E)}(z) remains the same along the z-axis and the accelerating field pulse has no flattop, the particle beam bunch experiences transverse focusing and defocusing fields. Depending on the relative position of the charged particle beam that is propagating in the DWA with respect to the peak of the electric field waveform, the short accelerating field pulse will provide different radial focusing or defocusing forces on the charged particles. For example, the charged particles can be either simultaneously transversely defocused and longitudinally compressed, or can be transversely focused and longitudinally decompressed. FIG. 3(a) illustrates an exemplary scenario, where the charged particle bunch, having an extent that spans from z1 to z2, is longitudinally compressed (Er>0) but is transversely defocused (Ez(z2,t)>Ez(z1,t)). FIG. 3(b) illustrates a different scenario, in which the charged particle bunch is longitudinally decompressed (Er<0) but is transversely focused (Ez(z2,t)<Ez(z1,t)). Therefore, for a charged particle bunch with a finite length that is traveling in a short accelerating bucket, the head and the tail of the bunch can experience different transverse kicks that can result in emittance growth and larger spot sizes at the target. While the spot size may be reduced by placing lenses between the DWA and the target, such lenses are often large in size to accommodate the large focusing field required for the full energy charged particle beam, and further increase the complexity and length of the accelerator system. The effects of the dispersive radial kicks, such as the ones that are illustrated in FIGS. 3(a) and 3(b), can be minimized by increasing the accelerating field's pulse length at the DWA entrance as long as practically possible at the time when the charged particle beam is entering the DWA. This pulse widening can be done by, for example, using a grid or foil at the DWA entrance and widening the length of the excited DWA section by simultaneously charging several contiguous sections of the DWA. The grid can then be removed and the pulse length can be reduced once the charged particle bunch has passed through the entrance area of the DWA. However, in such a scenario, the longitudinal extent of the wave bucket at the entrance may still not be long enough to transport the finite length particle beam bunch without significant transverse kicks. Examination of Equation (3) reveals that an additional radial electric field control capability can be implemented through the first term on the right hand side of Equation (3). To this end, in some embodiments, a modified DWA (MDWA) is provided to allow a portion of the DWA to operate as a high gradient dynamic lens, with focusing and defocusing capabilities. In other embodiments, a high gradient dynamic lens separate from the DWA can be provided to modify the focusing of the charged particle beam at the entrance of the DWA. High gradient lenses described in this patent document can be implemented based on a series of alternating layers of insulators and conductors that are stacked to one another to form a high gradient insulator (HGI) tube. Such a HGI tube includes sections with a hollow center to allow propagation of a charged particle beam of charged particles through the hollow center. Electrically conductive transmission lines are connected to the sections of the HGI tube to apply control voltages to the HGI tube. A lens control module, which can be one or more voltage sources, is configured to supply adjustable control voltages the transmission lines, respectively, to thereby establish an adjustable electric field profile over the sections of the HGI tube to effectuate a lens that modifies spatial profile of the charged particle beam at an output of the HGI tube to achieve a desired beam focusing or defocusing operation. This adjustable HGI tube is a charged particle transport device that allows adjusting the voltages to modify the particle propagation and energy parameters as the particles pass through the HGI tube. Therefore, a HGI lens is an adjustable charged particle lens and allows the same lens structure to provide various lens operations that may be difficult to achieve with a single lens in other lens designs. The HGI tube and the transmission line for the high gradient lenses can be implemented in ways similar to the HGI tube structure for DWA as described above. FIG. 4 illustrates a modified dielectric wall accelerator (MDWA) 400 in accordance with an exemplary embodiment of the described technology. The MDWA 400 includes a high gradient lens section 402, a main DWA section 404 and an end section 406. The operations of the main DWA section 404 were previously described in connection with FIGS. 2(A) to 2(C). Further details regarding the end section 406 will be described in the sections that follow. The high gradient lens section 402 of the MDWA 400 is further illustrated at the bottom of FIG. 4 as comprising a stack of alternate layers of insulators and conductors with a hollow center that form a high gradient insulator (HGI) tube, represented by a cross-section of an upper wall of the HGI tube. The voltage pulses V1, V2, . . . , VI are supplied to the HGI tube by a series of transmission lines 408. In one example embodiment, thickness of the transmission lines 408 is in the order of a few millimeters. In some embodiments, each transmission line can be charged by its own dedicated charging system, whereas in other embodiments, several transmission lines 408 can form a block that is charged by a common charging system. Each of the voltages V1, V2, . . . , VI produces an associated electric field E1, E2, . . . , EI in the corresponding section of the HGI tube. In accordance with the disclosed embodiments, by varying the transmission lines' 408 voltages V1, V2, . . . , VI from one section to the next section of the HGI tube, a variation of both the electric field gradient or intensity, and the electric field profile is effectuated. Therefore, by adjusting the voltage values that are supplied to the high gradient lens section 402, any desired electric field can be established at the entrance of the MDWA 400. For example, referring back to Equation (2), it is evident that if ∂ E z ⁡ ( z , t ) ∂ z remains constant, the radial electric field is perfectly linear and, therefore, a linear lens with little or no aberrations is produced. In practical implementations, however, it is often not feasible to produce a perfectly linear longitudinal electric field variation. Therefore, a substantially linear lens is often produced. In one example embodiment, the high gradient lens section 402 of the MDWA is configured to accelerate and focus the charged particle beam that travels through the HGI tube. FIG. 5 is a plot of longitudinal and radial electric fields produced in accordance with an exemplary embodiment. The plot in FIG. 5 illustrates the longitudinal 502 and radial 504 electric fields as a function of distance along the z-axis that are produced by applying voltages to a 20-cm long high gradient lens section of the MDWA. The electric fields that are illustrated in FIG. 5 accelerate and focus a positively charged particle beam that traverses through the high gradient lens. Similarly, the exemplary electric fields that are illustrated in FIG. 5 operate to decelerate and defocus a negatively charged particle beam that propagates through the high gradient lens. FIG. 6 is a plot of longitudinal and radial electric fields produced in accordance with another exemplary embodiment. The plots in FIG. 6 illustrate the longitudinal 602 and radial 604 electric fields as a function of distance along the z-axis that are produced by applying voltages to a 20-cm long high gradient lens section of the MDWA. The electric fields that are illustrated in FIG. 6 have the opposite polarity of the electric fields that are depicted in FIG. 5 and, as such, they decelerate and defocus a positively charged particle beam that traverses through the high gradient lens. Similarly, the exemplary electric fields that are illustrated in FIG. 6 operate to accelerate and focus a negatively charged particle beam that propagates through the high gradient lens. The high gradient lens section 402 of the MDWA 400 can, therefore, provide be configured to focus and accelerate a charged particle beam bunch before it reaches the DWA main section 404. As a result, the effects of transverse radial kicks at the entrance of a DWA without the high gradient lens section 402 are minimized. Incorporating the high gradient lens section 402 as part of the MDWA 400 also eliminates a need for having external lenses such as bulky magnetic lenses or electrode-based electrostatic lenses and, therefore, simplifies the design, manufacturing and maintenance of the particle accelerator system. It should be noted that the high gradient lens can be incorporated into various sections of the DWA. In various designs, the strongest focusing fields can be generated if the high gradient lens is located at the entrance of the DWA since the electric field can be ramped up from zero to its maximum allowable value. When operating a particle accelerator system, such as the particle accelerator 100 of FIG. 1, that is equipped with the MDWA, a matched charged particle beam can be focused to the tightest required spot on a target (e.g., a patient) by adjusting the voltages that are supplied to one or more sections of the high gradient lens, in addition to controlling the voltage ramping rates and properly synchronizing the on/off timing for the DWA charging switches. The MDWA that is configured this way to deliver the tightest spot provides a “baseline” performance for the charged particle beam system. In some applications, such as intensity modulated proton therapy, it is desirable to have the capability to deliver various spot sizes on the patient from shot to shot during a single treatment. In accordance with the disclosed embodiments, the baseline performance of a particle accelerator can be modified (e.g., degraded) to increase the spot size from the baseline setting. In some example embodiments, the injector subsystems of the particle accelerator system are slightly mismatched with the MDWA to produce a larger spot size than the baseline setting. FIGS. 7(a) to 7(f) illustrate how a mismatch between the injected beam and the DWA can affect the output beam characteristics for an exemplary accelerator configuration. In particular, the plots in FIGS. 7(a) to 7(f) show the change in various output beam parameters at the target (e.g., at the patient's location) as a function of injected beam's envelop slope, r′. FIG. 7(a) illustrates that the output beam energy remains relatively constant as a function of injected beam's slope, whereas, as shown in FIG. 7(b), the energy of the output beam within plus and minus one standard deviation from the peak value, which is represented by “1−σ energy” along the vertical axis, drops off substantially linearly as a function of increasing slope of the injected beam. FIG. 7(c) illustrates the change in output beam radius at 100%, 95%, 90% and 85% points (e.g., 100% corresponds to a radius including 100% of the protons in the bunch, 95% corresponds to a radius including 95% of the protons in the bunch, etc.) as a function of the injected beam's envelop. FIG. 7(d) illustrates the output beam's r.m.s. envelope as a function of the injected beam's slope. In FIG. 7(e) the output beam's slope is plotted against the injected beam's slope. The significance of the output slope plot can be appreciated by noting that two beams with the same spot size on a patient's skin but with different beam slopes produce different spot sizes when the beam reaches the target, such a tumor, which is located inside the body of the patient. In FIG. 7(f), the output beam's Lapostolle emittance is plotted as a function of the injected beam's slope. In some example embodiments, degrading the baseline performance can be additionally, or alternatively, accomplished by adjusting the synchronization between the traveling accelerating field and the charged particle bunch to allow the particle beam bunch to slip off the crest of the traveling wave field. This leads to a larger spot size and growth in emittance of the output beam. The amount of increase in the spot size and emittance growth both depend on how far the charged particle beam bunch has slipped from the crest. One approach to introduce a synchronization mismatch is to adjust the timing between the particle beam injector (e.g., at the input and/or output of the RFQ 106 that is illustrated in FIG. 1) and the MDWA of the particle accelerator. FIG. 8 illustrates the change in several output beam parameters as a function of timing delay between the injector and the DWA beams for an exemplary accelerator configuration. In particular, FIG. 8 shows the plots corresponding to Lapostolle emittance, beam radius, energy, beam slope and change in energy as a function of a delay time (i.e., delay time represents the time delay from a reference time value). It should be noted that the plots in FIG. 8 are not intended to necessarily convey that an optimum output beam parameter can be obtained when a particular timing delay is used. But rather these plots illustrate that changing the synchronization between the traveling accelerating field and the charged particle bunch can be used to modify different characteristics of the output beam from the baseline characteristics. In some embodiments, degrading the baseline performance can be additionally, or alternatively, accomplished by adjusting the electric field at one or more sections of the DWA. For example, the transmission lines to a small portion of the MDWA can be turned off to slow down the charged particle beam bunch with respect to the traveling accelerating field. Due to high accelerating gradient in the MDWA, the effects of turning off a section of transmission lines at the low energy end of the MDWA can be significant. For example, FIGS. 9(a) to 9(d) illustrate examples of changes in various output beam parameters as a function of the location of a misfired Blumlein block. In the plots of FIGS. 9(a) to 9(d), each Blumlein block is associated with a 2-cm section of the MDWA. FIGS. 9(a), 9(b) and 9(c) illustrate the r.m.s. beam size, the beam slope and the Lapostolle emittance, respectively, of the output beam at a target location as a function of the location of the misfired Blumlein block within the MDWA. In FIG. 9(d), the maximum, the minimum and the average output beam energies are plotted. Examination of FIGS. 9(a) to 9(d) reveals that the largest change in output beam characteristics occurs when a Blumlein block at the low energy end of the MDWA (e.g., less than 50 cm from the entrance of the MDWA) misfires. Therefore, in some embodiments, to produce spot sizes that are larger than the baseline spot size, charging voltages at one or more sections of the MDWA are either completely turned off or set to a value that is different from the baseline setting. When the charging voltages are turned off or modified from their baseline setting, the energy of the output beam is also decreased. In some embodiments, to compensate for the aforementioned lost energy, an additional DWA section can be added to the end of the MDWA to increase the energy of the charged particles. With reference to FIG. 4, an end section 406 of the MDWA 400 is illustrated that is constructed using alternate layers of insulators and conductors, as in other sections of the MDWA 400. In one particular example embodiment, the end section 406 is 2 cm long, the DWA main section 404 is 180 cm long, and the high gradient lens 402 is 20 cm long. The end section 406 of the MDWA 400 can be used to increase the energy of the transported beam. In particular, the transmission lines that supply voltages to the end section 406 of the MDWA 400 can remain in the “off” state (or a first state that allows the particle accelerator to operate in a baseline configuration) when baseline performance is needed. However, depending on the number and locations of the MDWA sections that were turned off for non-baseline beam transport, the transmission lines to one or more sections of the end section 406 can be energized to compensate for the lost energy of the charged particle beam. It should be noted that the end section 406 can also be used to compensate for energy loss when non-baseline performance is produced using other previously described techniques, such as when adjustments are made to create a slightly out-of-sync traveling accelerating field and charged particle bunch, and/or when the injector and the MDWA are slightly mismatched. In FIG. 4, the transmission lines 408 supply voltages to one or more sections of the combined MDWA and are under the control of a timing/control component, which may be implemented as part of the timing and control components 116 that is illustrated in FIG. 1. Alternatively, or additionally, separate control components may be used to control each section of the MDWA 400. Using the control and timing components, one or more voltage sources can be configured to supply a desired voltage value to each section and/or subsection of the MDWA to establish the desired longitudinal and transverse electric fields. During the baseline operation, the timing and control signals can, for example, enable focusing and acceleration of the charged particle beam as is propagates through the high gradient lens portion of the MDWA, provide pulses to the DWA main section in synchronization with the charged particle bunch, and/or to configure the end portion of the MDWA to produce a charged particle beam with desired baseline characteristics. To allow variations in the output charged particle beam characteristics (e.g., increase the output beam size), the timing and control components can configure one or more voltage sources to supply different voltage values to certain transmission lines of the MDWA to, for example, enable defocusing and deceleration of the charged particle beam as it propagates through the high gradient lens portion of the MDWA, provide pulses to the MDWA that are slightly out of synchronization with the charged particle bunch, and/or to configure the end portion of the MDWA to, for example, compensate for energy loss in the charged particle beam. The change in output beam characteristics can include, but is not limited to, changes in the beam energy, beam spot size, beam slope, beam emittance, beam uniformity, beam intensity and the like. FIG. 10 illustrates a set of operations, generally indicated at 1000, for shaping a charged particle beam in accordance with an exemplary embodiment. At 1002, a desired electric field across a plurality of sections of a dielectric wall accelerator (DWA) is established. The DWA comprises a high gradient lens section and a main DWA section, where the high gradient lens section and the main DWA section comprise a series of alternating layers of insulators and conductors with a hollow center, the series of alternating layers stacked together to form a single high gradient insulator (HGI) tube to allow propagation of a charged particle beam through the hollow center of the HGI tube. The DWA further comprises a plurality of transmission lines connected to the high gradient lens section, a plurality of transmission lines connected to the main DWA section, and one or more voltage sources configured to supply an adjustable voltage value to each transmission line of the plurality of transmission lines connected to the high gradient lens section and the main dielectric wall section. At 1004, the charged particle beam is guided through the DWA. FIG. 11 illustrates a set of operations, generally indicated at 1100, for operating a charged particle beam accelerator in accordance with an exemplary embodiment. At 1102, a charged particle beam produced by a charged particle source is guided or otherwise directed through a dielectric wall accelerator (DWA). The DWA comprises a high gradient lens section and a main DWA section, where the high gradient lens section and the main DWA section comprise a series of alternating layers of insulators and conductors with a hollow center, the series of alternating layers stacked together to form a single high gradient insulator (HGI) tube to allow propagation of a charged particle beam through the hollow center of the HGI tube. The DWA also includes a plurality of transmission lines connected to the high gradient lens section, a plurality of transmission lines connected to the main DWA section, and one or more voltage sources configured to supply an adjustable voltage value to each transmission line of the plurality of transmission lines connected to the high gradient lens section and the main dielectric wall section. At 1104, the one or more voltage sources are adjusted to supply a first set of voltage values to the high gradient lens section and the main DWA section to produce an output charged particle beam with a particular set of baseline characteristics where the output beam spot size is at or near the smallest beam spot size. In controlling the beam spot size, various control operations may be used to vary the beam spot size from the baseline beam spot size. For example, a second set of voltage values different from the first set of voltage values for the baseline characteristics of the beam can be applied to produce a larger output beam size than the baseline beam size. For another example, the timing between the traveling accelerating field and the charge particle beam may be controlled to deviate from the synchronization state for the DWA to produce a larger output beam size than the baseline beam size. For yet another example, the parameter of the beam incident to the DWA can be changed to produce a larger output beam size by the DWA. FIG. 12 illustrates a set of operations, generally indicated at 1200, for treatment of a patient using a charged particle accelerator system in accordance with an exemplary embodiment. At 1202, one or more target areas within the patient's body are irradiated with a charged particle beam that is output from the charged particle beam accelerator system. The charged particle beam system comprises a charged particle source such as an exemplary ion source, a dielectric wall accelerator (DWA). The DWA comprises a high gradient lens section, a main DWA section, where the high gradient lens section and the main DWA section comprise a series of alternating layers of insulators and conductors with a hollow center, the series of alternating layers stacked together to form a single high gradient insulator (HGI) tube to allow propagation of a charged particle beam through the hollow center of the HGI tube. The DWA also includes a plurality of transmission lines connected to the high gradient lens section, a plurality of transmission lines connected to the main DWA section, and one or more voltage sources configured to supply an adjustable voltage value to each transmission line of the plurality of transmission lines connected to the high gradient lens section and the main dielectric wall section. The charged particle accelerator system further comprises a timing and control component configured to produce timing and control signals to the ion source, the high gradient lens and the dielectric wall accelerator. At 1204, one or more voltage sources are adjusted to supply a first set of voltage values to the high gradient lens section and the main DWA section to produce an output charged particle beam with a particular set of baseline characteristics. It is understood that the various embodiments of the present disclosure may be implemented individually, or collectively, in devices comprised of various hardware and/or software modules and components. In describing the disclosed embodiments, sometimes separate components have been illustrated as being configured to carry out one or more operations. It is understood, however, that two or more of such components can be combined together and/or each component may comprise sub-components that are not depicted. Further, the operations that are described in the form of the flow charts in FIGS. 10 through 12 may include additional steps that may be used to carry out the various disclosed operations. In some examples, the devices that are described in the present application can comprise a processor, a memory unit and an interface that are communicatively connected to each other. For example, FIG. 13 illustrates a block diagram of a device 1300 that can be utilized as part of the timing and control components 116 of FIG. 1, or may be communicatively connected to one or more of the components of FIG. 1. In some example embodiments, the device 1300 may be used to control the timing and the value of voltages that are applied to the high gradient lens that is described in the present application. The device 1300 comprises at least one processor 1302 and/or controller, at least one memory 1304 unit that is in communication with the processor 1302, and at least one communication unit 1306 that enables the exchange of data and information, directly or indirectly, through the communication link 1308 with other entities, devices, databases and networks. The communication unit 1306 may provide wired and/or wireless communication capabilities in accordance with one or more communication protocols, and therefore it may comprise the proper transmitter/receiver antennas, circuitry and ports, as well as the encoding/decoding capabilities that may be necessary for proper transmission and/or reception of data and other information. Various embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), Blu-ray Discs, etc. Therefore, the computer-readable media described in the present application include non-transitory storage media. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes. While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments. Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document. For example, the exemplary embodiments have been described in the context of proton beams. It is, however, understood that the disclosed principals can be applied to other charged particle beams. Moreover, the modification and shaping of charged particle pulses that are carried out in accordance with certain embodiments may be used in a variety of applications that range from radiation for cancer treatment, probes for spherical nuclear material detection or plasma compression, or in acceleration experiments. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products.
046831096	claims	1. Apparatus for manipulating tools with respect to a nuclear fuel assembly at a work station, said apparatus comprising: a transportable support movable to and from a work position at the work station adjacent to the nuclear fuel assembly, said support including frame means defining an encompassed space, a tool carriage mounted on said support and disposed in said encompassed space, a plurality of tools mounted on said tool carriage, said tool carriage including selection means accommodating disposition of a selected one of said tools in a work configuration with respect to the associated nuclear fuel assembly, motive means on said support for effecting movement of said tool carriage and the tools carried thereby with respect to said frame means within said encompassed space along either of two orthogonal axes and movement of the selected tool along a third axis with respect to said frame means orthogonal to said first two axes for performing work with respect to the nuclear fuel assembly, and control means for remotely controlling operation of said manipulation means. 2. The apparatus of claim 1, wherein said tool carriage is mounted for rotational movement for selectively positioning said tools in said work configuration. 3. The apparatus of claim 2, wherein said tool carriage is rotatable about an axis disposed substantially vertically in use. 4. The apparatus of claim 1, wherein said motive means includes fluid drive means for effecting movement along said axes. 5. The apparatus of claim 1, wherein said tool carriage supports four of said tools. 6. The apparatus of claim 1, wherein said tools are designed for removing debris from the nuclear fuel assembly. 7. The apparatus of claim 6, wherein said tools include a pick, and a fluid lance, and a brush, and a tweezer. 8. The apparatus of claim 1, and further including video camera means carried by said support for remote viewing of the nuclear fuel assembly and the work performed thereon. 9. The apparatus of claim 1, wherein said tool carriage includes means for mounting each of said tools for movement with respect to said tool carriage, and means biasing each said tool toward a predetermined position. 10. Apparatus for manipulating a tool with respect to a nuclear fuel assembly at a work station, said apparatus comprising: a tool carriage, a tool holder for holding an associated tool, said tool holder being mounted on said tool carriage for reciprocating movement with respect thereto along a predetermined axis between extended and retracted conditions, yieldable means resiliently urging said tool holder to its extended condition with a predetermined force less than the minimum force which could damage the associated nuclear fuel assembly, drive means for effecting reciprocating movement of said tool carriage along said axis for manipulating said tool holder and the tool held thereby to perform work with respect to the associated nuclear fuel assembly, whereby engagement of the nuclear fuel assembly by the tool with a force in excess of said predetermined force in response to movement of said tool carriage toward the nuclear fuel assembly causes said tool holder to move from its extended condition toward its retracted condition with respect to said tool carriage, and means responsive to movement of said tool holder a predetermined distance along said axis from its extended condition toward its retracted condition for generating a signal. 11. The apparatus of claim 10, wherein said yieldable means includes a helical compression spring. 12. The apparatus of claim 10, wherein said drive means includes means for effecting reciprocating movement of said tool carriage along any of three orthogonal axes. 13. The apparatus of claim 12, and further including resilient means yieldable in response to engagement of the nuclear fuel assembly by the tool with a force in a direction other than along said predetermined axis. 14. The apparatus of claim 10, and further including video camera means carried by said drive means for remote viewing of the nuclear fuel assembly and the work performed thereon. 15. The apparatus of claim 10, and further including a plurality of said tool holders for respectively holding a plurality of associated tools, said tool holders being mounted on said tool carriage for reciprocating movement with respect thereto respectively along a plurality of predetermined axes between extended and retracted conditions. 16. The apparatus of claim 15, wherein said tool carriage includes selection means accommodating disposition of a selected one of said tools in a work configuration with respect to the associated nuclear fuel assembly. 17. A system for working on an elongated nuclear fuel assembly suspended vertically and submerged in a spent fuel pool having a plurality of fuel assembly racks at the bottom thereof, said system comprising: a work platform disposable in the pool and adapted to be supported on the fuel assembly racks, said platform having an opening therein disposed in registry with a selected one of the underlying racks; guide means carried by said platform for guiding the suspended fuel assembly into said opening and the selected rack to accommodate vertical movement of the fuel assembly into and out of the rack to make different portions of the fuel assembly accessible from said platform; and tool manipulating apparatus disposable on said platform adjacent to said opening, said tool manipulating apparatus including a tool carriage, a plurality of tools mounted on said tool carriage, said tool carriage including selection means accommodating dispostition of a selected one of said tools in a work configuration with respect to the associated fuel assembly, motive means for effecting movement of said tool carriage and the selected tool along any of three orthogonal axes for performing work with respect to the fuel assembly, and control means for remotely controlling operation of said motive means. 18. The system of claim 17, wherein said tools are designed for removal of debris from the fuel assembly. 19. The system of claim 18, and further including shield means disposed in surrounding relationship with said opening and engageable with the nuclear fuel assembly during vertical movement thereof for directing loose debris onto said platform and preventing it from falling through said opening and into the associated rack. 20. The system of claim 17, and further including a support stand mounted on said platform for stabilizing the fuel assembly when it is supported over said opening. 21. The system of claim 20, wherein said support stand includes a support plate movable between a supporting position overlying said opening for supporting relationship with the lower end of the fuel assembly, and a retracted position withdrawn from said opening for accomodating vertical movement of the fuel assembly into and out of the associated rack. 22. The system of claim 20, wherein said support stand is transportable to and from a support location on said work platform. 23. The system of claim 17, wherein said tool manipulating apparatus is transportable to and from a work position on said work platform. 24. A system for working on an elongated nuclear fuel assembly suspended vertically and submerged in a spent fuel pool having a plurality of fuel assembly racks at the bottom thereof, said system comprising: a work platform disposable in the pool and adapted to be supported on the fuel assembly racks, said platform having an opening therein disposed in registry with a selected one of the underlying racks; guide means carried by said platform for guiding the suspended fuel assembly into said opening and the selected rack to accommodate vertical movement of the fuel assembly into and out of the rack to make different portions of the fuel assembly accessible from said platform; and tool manipulating apparatus disposable on said platform adjacent to said opening, said tool manipulating apparatus including a tool carriage, a plurality of tool holders for respectively holding a plurality of associated tools, each of said tool holders being mounted on said tool carriage for reciprocating movement with respect thereto along a predetermined axis between extended and retracted conditions, said tool carriage including selection means accommodating disposition of a selected one of said tool holders in a work configuration with respect to the associated fuel assembly, motive means for effecting movement of said tool carriage along any of three orthogonal axes including said predetermined axis for performing work with respect to the fuel assembly, yieldable means resiliently urging each of said tool holders to its extended condition with a predetermined force less than the minimum force which could damage the associated fuel assembly, whereby engagement of the fuel assembly by a tool with a force in excess of said predetermined force in response to movement of said tool carriage toward the fuel assembly along said predetermined axis causes said tool holder to move from its extended condition toward its retracted condition with respect to said tool carriage, and control means for remotely controlling operation of said motive means, said control means including means responsive to said movement of said tool holder a predetermined distance along said axis from its extended condition toward its retracted condition for generating a signal. 25. The system of claim 24, wherein said tool manipulating apparatus includes counterweight means for counterbalancing said apparatus during movement thereof along a vertical axis. 26. The system of claim 24, wherein said tool carriage further includes resilient means yieldable in response to engagement of the nuclear fuel assembly by the tool with a force in a direction other than along said predetermined axis.
	description	This application claims the benefit of U.S. Provisional Application No. 62/772,986 filed Nov. 29, 2018, which is incorporated herein by reference in its entirety. The present invention relates generally to systems for storing used or spent nuclear fuel, and more particularly to an improved nuclear fuel cask which forms part of the storage system. In the operation of nuclear reactors, the nuclear energy source is in the form of hollow zircaloy tubes filled with enriched uranium, collectively arranged in multiple assemblages referred to as fuel assemblies. When the energy in the fuel assembly has been depleted to a certain predetermined level, the used or “spent” nuclear fuel (SNF) assemblies are removed from the nuclear reactor. The standard structure used to package used or spent fuel assemblies discharged from light water reactors for off-site shipment or on-site dry storage is known as the fuel basket. The fuel basket is essentially an assemblage of prismatic storage cells each of which is sized to store one fuel assembly that comprises a plurality of individual spent nuclear fuel rods. The fuel basket is arranged inside a cylindrical metallic storage canister (typically stainless steel), which is often referred to as a multi-purpose canister (MPC), which forms the primary containment. The canister is then placed into an outer ventilated overpack or cask, which forms the secondary containment, for safe transport and storage of the multiple spent fuel assemblies. The ventilation utilizes ambient cooling air to dissipate the considerable heat still emitted by the spent fuel. The used or spent nuclear fuel contained in the fuel basket inside the fuel canister is stored in an inert gas atmosphere formed within the canister. Guaranteed sequestration of heat and radiation emitting used nuclear fuel from the environment under all storage or transport conditions is an essential design requirement for the canister. This assurance of confinement requirement has been fulfilled in the present state-of-the-art by hermetically seal welding the top lid to the canister shell after the spent fuel has been loaded into the canister (typically under water such as in the spent fuel pool of a nuclear reactor). The all-welded canister provides guaranteed confinement of the contents, but makes the stored fuel difficult-to-access if repackaging is required at a later date. While lid cutting tools to sever the lid from the canister shell have been successfully developed and demonstrated, the cutting operation is inherently dose-accretive, cumbersome, and time-consuming requiring metal chip and lubricant management during the process. Improvements in the traditional spent nuclear fuel canisters which overcomes the foregoing deficiencies are desired. To overcome the foregoing limitations in the art for retrieving the spent nuclear fuel (SNF) contents from “all-welded” fuel canister constructions presently used in the nuclear industry, a new and improved spent nuclear fuel canister is disclosed herein which not only maintains the essential features of the canister's structural ruggedness for protecting the fuel, but also makes the fuel more readily accessible without the foregoing cutting process, and with minimum human effort and radiation exposure to the workers. Some embodiments further include heat dissipation features for significantly increasing the heat rejection capability of the canisters, thereby safeguarding the structural integrity of the SNF stored therein. Also importantly, the SNF canisters disclosed herein advantageously maintain the same preferred small dimensions and profile (i.e. height and diameter) of prior canisters with seal welded lids, thereby allowing the new canisters to be used interchangeably in existing outer transport and storage overpacks or casks without modification. The SNF canister according to the present disclosure includes a multi-thickness shell and compact bolted closure lid-to-shell joint for ready access to the fuel contents inside. This eliminates the time-consuming and cumbersome prior cutting processes described above which are required to sever a welded joint between the lid and shell in welded lid designs. In one embodiment, the present lid may be directly bolted to the top of the shell. To accommodate the bolting and seals required, a multi-thickness shell is provided having a top fastening portion that comprises a reinforcement structure in the form of an annular mounting boss integrally formed with the shell. The top fastening portion of the shell has a greater transverse wall thickness than the wall portion of the shell below, thereby providing additional purchase for engaging the bolts at the bolted lid joint. In some embodiments, the mounting boss may have a wall thickness equal to or greater than at least twice the thickness of the lower shell wall. In various embodiments described herein, the upper annular mounting boss may protrude radially inwards into the cavity of the shell beyond its lower inner surface, or alternatively protrude radially outwards beyond the lower outer surface of the shell. The boss or fastening portion of the shell comprises a plurality circumferentially spaced and upwardly open threaded bores formed in the top of the shell at the fastening portion. The bores threadably engage the bolts which extend longitudinally through the lid. An inner and outer seal are provided to seal the containment cavity of the SNF canister and provide redundant high integrity leak barriers. In some preferred embodiments, the top mounting boss/fastening portion may be formed as a monolithic unitary structural portion of the shell which may be one piece. In other embodiments, the mounting boss/fastening portion may be a discrete element seal welded to the lower smaller thickness portion of the shell. The closure lid has an annular mounting flange receiving the through bolts. The flange is seated on the top end of canister shell. Significantly, the mounting flange does not protrude radially beyond the outer surface of the either the upper fastening portion or lower portions shell to minimize the outside diameter of the canister necessary for storing the canister inside the an outer radiation shielded overpack or cask for transport/storage. This unique lid and bolting construction and arrangement advantageously results in a compact lid design, thereby keeping the outer cask's outside diameter to the smallest possible which is an essential part of a design that complies with the NRC's 10CFR71 regulations. Although bolted lids may be used in the bulker radiation shielded outer transport/storage casks, such bulkier designs are not suit for the inner SNF canister which must maintain the smallest outer diameter and profile possible without substantially reducing the number of spent fuel assemblies which be storage inside the canister. In one embodiment, the canister may further comprise a plurality of radial cooling fins arranged perimetrically on the outer surface of the shell to enhance heat dissipation. The fins may be welded directly to the outer surface of the shell or may be integrally formed therewith to provide direct contact. This ensures an effective conductive heat transfer path from the shell to the outer environment surrounding the canister, thereby allowing the fins to act as heat radiators. In some constructions, the fins may be disposed in an annular 360 degree recessed lower area of the outer shell formed by the mounting boss. By locating the fins in the recessed area below the mounting boss, the fins advantageously do not protrude radially outwards beyond the lid, shell, and bottom baseplate of the canister in some implementations to maintain the desired small outside diameter of the canister package, and importantly to protect the fins from damage when handling and moving the canister during the spent fuel dewaters, staging, and transport operations. In one aspect, a canister for spent nuclear fuel storage comprises: a longitudinal axis; an elongated shell extending along the longitudinal axis, the shell including a top end and a bottom end; a cavity extending along the longitudinal axis inside the shell for storing spent nuclear fuel; a baseplate attached to the bottom end of shell and enclosing a lower portion of the cavity; a closure lid detachably fastened to the top end of the shell and enclosing an upper portion of the cavity; and a plurality of mounting bolts extending longitudinally through the lid and threadably engaging the top end of the shell; wherein the canister is configured for placement inside an outer overpack with radiation shielding. In another aspect, a canister for spent nuclear fuel storage comprises: a vertical longitudinal axis; a cylindrical shell extending along the longitudinal axis, the shell including a top end, a bottom end, and an outer surface; an internal cavity extending between the top end and bottom end of the shell along the longitudinal axis for storing spent nuclear fuel; a baseplate attached to the bottom end of the shell and enclosing a lower portion of the cavity; a closure lid detachably fastened to the top end of the shell and enclosing an upper portion of the cavity, the lid having a circular body comprising a first portion and a second mounting flange portion protruding radially outwards beyond the first portion; and a plurality of mounting bolts extending longitudinally through the mounting portion of the lid and threadably engaging the top end of the shell; wherein the mounting flange portion of the lid does not protrude radially outwards beyond the outer surface of the shell; wherein the canister is configured for placement inside an outer overpack with radiation shielding. In another aspect, a canister for spent nuclear fuel storage comprises: a vertical longitudinal axis; a cylindrical shell extending along the longitudinal axis, the shell including a top end and a bottom end; a cavity extending along the longitudinal axis inside the shell for storing spent nuclear fuel; a baseplate attached to the bottom end of shell and enclosing a lower portion of the cavity; a closure lid detachably fastened to the top end of the shell and enclosing an upper portion of the cavity; and a plurality of mounting bolts extending longitudinally through the lid and threadably engaging the top end of the shell; and a plurality of longitudinally-extending cooling fins protruding radially outwards from the shell, the fins spaced perimetrically apart around the shell; wherein an outer surface of the lid is substantially flush with an outer surface of the top end of the shell; wherein the canister is configured for placement inside an outer overpack with radiation shielding. A system for storing spent nuclear fuel comprises: a longitudinal axis; an elongated outer cask comprising a double-walled first shell including a radiation shielding material, a first lid attached to a top end of the first shell, and an internal first cavity; an elongated inner cylinder canister positioned in the first cavity of the first shell, the cylinder comprising: a single-walled second shell extending along the longitudinal axis, the second shell including a top end and a bottom end; a second cavity extending along the longitudinal axis inside the second shell, the second cavity containing spent nuclear fuel; a baseplate attached to the bottom end of shell and enclosing a lower portion of the second cavity; a second lid detachably fastened to the top end of the second shell and enclosing an upper portion of the second cavity; and a plurality of mounting bolts extending longitudinally through the second lid and threadably engaging a plurality of blind threaded bores formed the top end of the second shell; the threaded bores formed in a radially projecting mounting boss extending circumferentially around the top end of the second shell, the mounting boss having a greater transverse first wall thickness than a transverse second wall thickness of lower portions of the second shell below the mounting boss. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. All drawings are schematic and not necessarily to scale. Features shown numbered in certain figures are the same features which may appear un-numbered in other figures unless noted otherwise herein. The features and benefits of the invention are illustrated and described herein by reference to exemplary embodiments. This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. Accordingly, the disclosure expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features. In the description of embodiments disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. As used throughout, any ranges disclosed herein are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls. FIG. 1 depicts a system for storing and transporting radioactive spent nuclear fuel (SNF) which incorporates a spent fuel canister 100 with compact bolted lid according to the present disclosure. The system generally includes an outer vertically ventilated overpack (VVO) or cask 20 defining a vertical longitudinal axis LA. Cask 20 may have a lid 21 and a composite construction including an outer cylindrical shell 22, inner cylindrical shell 23, and radiation shielding material 24 disposed in the annulus between the shells. In some embodiments, the shielding material 24 may comprise concrete, lead, boron-containing materials, or a combination of these or other materials effective to block and/or attenuate gamma and neutron radiation emitted by the SNF enclosed by the cask. Cask 20 has an elongated body including an open top 27 for inserting canister 100 into cavity 28, a bottom end 25, cylindrical sidewall 29 extending between the ends, and an internal canister cavity 28 defined by the inner shell 23. Cavity 28 extends completely through the cask along the longitudinal axis LA from the top to bottom end. The cavity 28 has dimensions and a transverse cross-sectional area which holds only a single SNF canister 100 in one embodiment. Cask 20 includes an interior surface 23-1 adjacent to canister cavity 28 and opposing exterior surface 22-1. Cask 201 may be comprised of a single long cylinder body, or alternatively may be formed by a plurality of axially aligned and vertically stacked cylinder segments seal welded together at the joints between the segments to collectively form the cask body. The bottom end 25 of cask 20 may be enclosed by circular base 26 attached thereto, such as via circumferential seal welding. A canister support pad 26-1 of cylindrical shape may be disposed on top of the base 26 inside canister cavity 28 to support the spent fuel canister 100. The pad may be formed of concrete in one embodiment. The cavity 28 of cask 20 may be ventilated by ambient cooling air to remove decay heat emitted by the SNF stored inside the canister 100. Cask 20 may therefore include one or more air inlets 30 communicating with a lower portion of cavity 28 and one or more air outlets 31 communicating with an upper portion of the cavity. Air flows radially inwards through inlets 30, upwards through the cavity, and radially outwards through outlets 31 (see directional airflow arrows). The open top end 27 of the cask 20 is closed by a removable lid detachably mounted to the cask. The outlet ducts 31 may be formed between the lid and top of the cask in some embodiments as shown. FIGS. 1-14 depict spent fuel canister 100 with compact bolted lid according to a first embodiment of the present disclosure in further detail. The present canister advantageously comprises a bolted joint between the removable top closure lid and the canister body as previously described herein, thereby advantageously providing ready access to the SNF therein for repackaging or other purposes. The bolted lid joint is further described in the discussion which follows. Canister 100 includes an elongated cylindrical body 103 comprising a single shell 106 including an open top 101, an open bottom 102, and sidewall 109 extending therebetween along a vertical longitudinal axis LA of the canister. Axis LA coincides with the geometric vertical centerline of the canister. Canister 100 further includes a bottom baseplate 110 and a top closure lid 120. Shell 106 may be of monolithic unitary structure in one embodiment formed of a single material. Shell 106 further includes an inner surface 107 and opposing outer surface 108. A longitudinally-extending fuel cavity 105 extends between the top and bottom ends 101, 102 of the shell along longitudinal axis LA. Cavity 105 is configured to hold a conventional fuel basket 60 comprising a prismatic array of longitudinally-extending fuel storage cells 62. Cells 62 of the fuel basket may be defined by a cluster of elongated tubes 61 (shown), or alternatively interlocked cell dividers. Both designs are used and well known in the art without further elaboration necessary. The invention is not limited by the construction or configuration of the fuel basket used. The cells 62 are each configured for holding a single spent fuel assembly containing plural used or spent fuel rods removed from the reactor core. Such fuel assemblies are well known in the art without further elaboration. The spent fuel still emits considerable amounts of decay heat which is removed by the air-cooled ventilation system of the outer cask 20, as previously described herein. The baseplate 110 is hermetically seal welded to the bottom end 102 of the shell 106. In one embodiment, the baseplate may have a larger diameter than bottom end of the shell such that the baseplate protrudes radially outwards beyond the shell (see, e.g. FIG. 10). This arrangement protects the longitudinal cooling fins 140 if provided, as further described herein. In other embodiments without fins, the baseplate 110 may have the same diameter as the bottom end of shell 106 such that the outward side surface of the baseplate is substantially flush with the outer surface 108 of the shell (see, e.g. FIG. 19). The first embodiment of a top closure lid 120 variously seen in FIGS. 1-14 will now be described in greater detail. FIGS. 10-12 show the lid in larger detail. Lid 120 may have a multi-stepped construction in one embodiment comprising a circular body including a top surface 121, bottom surface 122, an upper portion 123 adjacent the top surface, lower portion 124 adjacent the bottom surface, and an intermediate portion 125. Lower portion is configured for insertion into the upper portion of cavity 105 of canister shell 106 as shown. Accordingly, lower portion has an outside diameter D4 which is smaller than the inside diameter D3 of at least the top end 101 of shell 106 measured inside cavity 105. Intermediate portion 125 protrudes radially outwards beyond the upper and lower portions 123, 124 and defines an upwardly and downwardly exposed portion thereby forming an annular mounting flange 125-1 which is part of the bolted lid-to-shell joint. The mounting flange has an outside diameter D5 which is larger than outside diameter D4 of lower portion 124 and inside diameter D3 of shell 106. Preferably, in one embodiment, diameter D5 is substantially the same as outside diameter D1 of the shell 106 measured proximate to the top end 101 of shell 106 such that flange 125-1 does not protrude substantially beyond the shell in the radial direction. This advantageously maintains the narrow profile and dimensions of the canister 100 which keeps the inside diameter of the outer overpack or cask 20 as smaller as possible. The canister thus has an overall and collective diameter (i.e. D5 and D1) commensurate with existing SNF canisters having seal welded lids. The underside (i.e. downward facing surface) of mounting flange 125-1 defines an annular sealing surface 125-2 configured to abut and seat on the top end of the shell when the lid is emplaced thereon (see, e.g. FIG. 11). The interface between the sealing surface 125-2 and top end 101 of shell 106 is preferably one of flat-to-flat. Lid 120 further includes an annular step-shaped upper shoulder 177 at a transition between the intermediate mounting flange 125-1 and upper portion 123, and an annular step-shaped lower shoulder 128 at a transition between mounting flange and the lower portion 124. Lower shoulder 128 engages the inside edge of the top end of the shell 106 inside cavity 105 at to center the lid on the shell. Lower shoulder 128 further provides a sealing interface, as further described herein. Mounting flange 125-1 comprises a plurality of longitudinal bolt through bores or holes 126 which extend completely through the flange. Bolt through holes 126 are configured for receiving the at least partially threaded shanks 127-1 of threaded fasteners which may be bolts 127 in one embodiment (see, e.g. FIGS. 10-12). Bolts 127 further have a diametrically enlarged tooling head 127-2 configured for engaging and applying a tool thereto to tighten or loosen the bolts. The underside of tooling heads 127-2 engage the upward facing surface of the mounting flange 125-1 (best shown in FIG. 11). Through holes 126 may be unthreaded in one preferred embodiment, but can be threaded in other embodiments. Top portion 123 may have any suitable outside diameter D6 which is smaller than diameter D5 of the intermediate portion 125/mounting flange 125-1 to provide access to the through holes 126 for inserting the bolts therethrough. The lid bolts preferably may be slender, for example about ½-inch diameter in some embodiments with long threaded length (e.g. at least 4 inches long). By using a greater number of smaller diameter slender bolts rather than few larger diameter bolts, the radial projection of the lid 1q20 may advantageously be kept to a minimum without adversely affecting the lid-to-shell hermetic seal and in turn minimizes the outside diameter of the canister 100. Bolt through holes 126 are arranged perimetrically around the mounting flange 125-1 and spaced circumferentially apart covering a full 360 degrees of the flange. Preferably, through holes 126 are uniformly spaced apart to provide even sealing pressure around the entire perimeter of the closure lid 120 when the bolts are tightened. The centerline of through holes 126 each defines a bolt axis BA. The plurality of through holes 126 collectively fall on and define a bolt circle BC intersecting bolt axes BA and extending circumferentially around the mounting flange 125-1. The top end 101 of shell 106 comprises a plurality of perimetrically arranged and circumferentially spaced apart threaded sockets or bores 130 formed in the top end of the body of the shell 106. Bores 130 are vertically oriented and upwardly open for threadably receiving and engaging the threads on shanks 127-1 of bolts 127. Preferably, at least the lower portion of bolt shanks 127-1 are therefore threaded. Bores 130 are blind bores meaning the bottom ends of the bores are closed (see, e.g. FIG. 11). Bores 130 fall on the bolt circle BC and thus may each be coaxially aligned with a bolt axis BA of lid through holes 126 by proper rotational positioning of the lid on the shell. The bores 130 are formed between the inner surface 107 and upper outer surface 108a of shell 106 in the annular mounting boss 132 of the shell which defines top fastening portion 131, as further described below. To structurally reinforce the canister shell 106 for the bolting, the top end 101 of shell 106 is radially thickened to form an outwardly protruding annular mounting boss 132 integrally formed with the shell. Boss 132 extends around the entire circumference of the upper portion of the shell and vertically downwards from top end 101 of the shell 106. Boss 132 may be about 6 inches high in one non-limiting embodiment. The boss defines a top fastening portion 131 of the shell having a greater transverse wall thickness T1 (measured perpendicularly to longitudinal axis LA) than the wall thickness T2 of the portions of the shell below between the bottom end 102 of the shell and the fastening portion 131. This additional thickness provides extra purchase and structurally reinforces the top end of shell 106 for forming the threaded bores 130. In the illustrated embodiment, the annular mounting boss 132 may protrude radially outwards beyond the lower outer surface 108b of the lower portion of the shell 106 giving the shell a stepped outer surface 108. The lower outer surface 108b is thus recessed radially inwards from the upper outer surface 108a defined by the boss 132 such that outer surface 108a lies in a circular vertical plane which is offset and spaced farther away from the longitudinal axis LA of shell 106 than the lower outer surface 108b which lies in a different circular vertical plane (see, e.g. FIG. 11). It bears noting that the mounting boss 132/fastening portion 131 of the canister shell 106 is distinct from merely forming a conventional radially projecting flange on the top end of a shell used in bolted head flanged joints in which the shank of the fastener projects completely through mating flanges and a nut is threaded onto the bottom exposed shank portion. By contrast, the present mounting boss 132/fastening portion 131 of shell 106 is a substantially taller/higher thickened portion at the top end of the shell as shown in FIG. 11 which provides the important function of structurally reinforcing the shell for forming the threaded blind bores 130, not merely for accommodating a bolted lid-to-shell joint. Accordingly, embodiments of the present mounting boss 132/fastening portion 131 preferably have a height measured parallel to longitudinal axis LA which is greater than at least three times its radial/transverse wall thickness T1, and some embodiments greater than at least five times. The radially offset between the upper outer surface 108a and lower outer surface 108b of the canister shell 106 defines an outwardly open annular recess 141 extending a full 360 degrees around the circumference of the shell in preferred embodiments. The annular recess extends from the bottom of the mounting boss 132 to the bottom baseplate 110. According to another aspect of the invention, the canister 100 may comprise a plurality of longitudinally-extending cooling fins 140 protruding radially outwards from the shell. This provides additional cooling surface area for dissipating the heat emitted by the SNF stored in side canister 100. The fins are arranged perimetrically around the entire circumference of the shell 106 and spaced circumferentially apart, preferably at regular intervals with uniform spacing therebetween. The fins have a vertical length which extends for a majority of the vertical length of the shell to maximize the effective heat transfer area of the canister. Fins 140 may be formed integrally with the shell as a monolithic unitary structural portion thereof using a thick plate stock for the shell machined to form the fins. A typical plate stock may be 1¼-inch thick with machined rectangular fins ¾-inch high by ½-inch thick space at a 1¼-inch pitch around the circumference of the canister shell 106. Alternatively, the fins 140 may be discrete structures welded to the outer surface 108 of the shell 106. Fins 140 may be longitudinally straight structures including opposing side major surfaces and a straight vertical longitudinal edge as shown. In one embodiment, the fins 140 may have a wedge-shaped transverse cross section in which the side major surfaces converge moving radially outwards (best shown in FIG. 14). In other possible, embodiments, the side major surfaces may be parallel to each other. In one preferably arrangement, the fins 140 may be disposed on the lower outer surface 108b of shell 106 below the enlarged mounting boss 132-fastening portion 131 of the shell. Fins 140 extend vertically from the bottom of mounting boss 132 to the bottom baseplate 110 of the canister. In one preferred but non-limiting arrangement, the cooling fins 140 may be completely disposed within the outwardly open annular recess 141 of the shell 106. This protects the fins from damage during handling and transport of the canister and advantageously maintain the desired small outside diameter of the canister 100 for storage in the outer radiation shielded cask 20. Accordingly, in this embodiment, fins 140 do not protrude radially outwards beyond the upper reinforced fastening portion 131 (i.e. boss 132) of the shell 106. The fins further may additionally not protrude radially beyond the mounting flange 125 of lid 120. And in some embodiments, the fins may further also not protrude radially beyond the baseplate 110 of the canister 100 to maximize protection of the fins from structural damage during handling of the canister and minimize the radial projection of the fins to maintain the small canister diameter. In one embodiment, the top ends of the fins 140 may abut the underside (i.e. downward facing surface) of the annular boss 132 (see, e.g. FIG. 11), or alternatively terminate proximate thereto without contact. The opposite bottom ends of the fins 140 may terminate at a point proximate to but slightly spaced above the baseplate 110 to provide access for circumferentially seal welding the baseplate to bottom end 102 of the shell (see, e.g. FIGS. 5 and 10). For canisters containing a moderate heat load, its finned surface may be sufficiently effective to keep the peak fuel cladding temperature of the SNF inside the canister moderate (defined as <300 degrees C.) and thus advantageously permit the use of a less expensive inert gas such as nitrogen in lieu of helium, as the fill gas in the canister. Any suitable metallic materials may be used for constructing the lid 120, shell 106, plate 108, and fins 140. In one embodiment, stainless steel may be used for corrosion protection. Welding-friendly copper-nickel alloys and duplex stainless steel are also acceptable materials. The longitudinal fin 140 arrangement discussed above applies to vertically stored canisters such as in the HI-STORM storage system available from Holtec International. In storage systems that employ horizontally oriented canisters, the direction of the fin on the shell must be circumferential (preferably, helical) to effect improvement in heat rejection. Circumferentially oriented fins can also be effectively utilized to eliminate hide-out crevices formed at the junction of the horizontal canister and rails that support it. FIGS. 10 and 11 show the lid 120 fully seated, bolted, and sealed to the top fastening portion 131 of canister shell 106. The outer surface 125-3 of the mounting flange 125 of lid 120 does not project radially outwards beyond the upper outer surface 108a formed by the top fastening portion 131 defined by the annular mounting boss 132 of the shell. Accordingly, surfaces 125-3 and 108a lies in the same circular vertical plane Vp. The longitudinal edges 142 of cooling fins 140 occupying the annular recess 141 on the shell 106 do not protrude radially outwards beyond the top fastening portion 131 or lid 120; the edges also lying in the same vertical plane Vp. Each mounting bolt 127 passes vertically through its respective bolt through hole 126 in the intermediate mounting flange 125 of the lid and directly threadably engages the shell via the threaded bores 130 formed through the upward facing annular end surface 111 at the top end 101 of the shell. In order to keep the outer diameter of the canister assembly to minimum for providing the desired compact small profile lid construction which emulates existing small profile welded rather than bolted canister lids for packaging in radiation shielded outer overpacks such as cask 20 previously described herein, special spatial relationships are created by the present lid as shown in FIG. 11. The radial distance R1 between the longitudinal axis LA of canister 100 and bolt axes BA/bolt circle BC is less than both the radial distance R6 between upper outer surface 108a of shell 106 and axis LA, and radial distance R3 between outer surface 125-3 of lid mounting flange 125 and axis LA. Radial distance R1 however is greater than radial distance R5 between axis LA and inner surface 107 of shell 106, and radial distance R4 between axis LA and outer surface 124-1 of lid lower portion 124 inside shell cavity 105. Radial distance R1 is also greater than radial distance R7 between axis LA and outer lower surface 108b of shell 106. Radial distance R2 between longitudinal axis LA and outer surface 123-1 of lid upper portion 123 is less than R1, R3, and R6, but greater than R4 and R5 in one embodiment. R2 may be substantially the same as R7 in one embodiment. By keeping the outer diameter of the canister as small as possible, the outer transport/storage cask 20 dimensions are advantageously minimized which reduces fabrication costs and facilitates handling the large heavy casks with lifting equipment. To seal the lid 120 to shell 106, a pair of circumferential seals is provided including an annular inner seal 150 and annular outer seal 151. Inner seal 150 seals the lower portion 124 of the lid to the inner surface 107 of shell 106. A piston type seal arrangement may be provided as shown comprising an outward facing annular piston groove 152 formed in the outer surface 124-1 of lid lower portion 124 in which inner seal 150 is retained. When the lid 120 is placed on the top fastening portion 131 of the shell, the smaller diameter lid lower portion 124 is inserted into inside the upper portion of shell cavity 105. Inner seal 150 slides down along the inner surface 107 of the shell until the lid is fully seated on the canister. The circumferential outer seal 151 seals the step-shaped lower shoulder 128 of lid 120 to the top annular end surface 108 of the shell 106. An annular groove 153 is formed at the innermost corner edge of end surface 108 which retains the outer seal 151. The inner and outer seals 150, 151 provide two independent high integrity leak barriers advantageously creating redundant protection against leakage of gaseous matter from inside the canister 100. Any suitable annular seals may be used. In one embodiment, the seals may be O-rings formed of a suitable sealing material such as without limitation flexible elastomeric materials. FIGS. 15-25 depict a spent nuclear fuel (SNF) canister 200 with compact bolted lid according to a second embodiment of the present disclosure in further detail. SNF canister 200 is similar to canister 100. Similar parts will not be described in detail or numbered in the figures for the sake of brevity. There are some notable differences in design. For example, the shell 206 of canister 200 is substantially similar to shell 106 of canister 100 with exception that is does not have a step-shaped outer surface with annular recess. Instead, the inner surface of the shell is step shaped as further described below. In addition, canister 200 may be finless as shown, or alternatively may be equipped with external cooling fins if heat emitted by the SNF is considerable. Top closure lid 220 has a different configuration than lid 120 of canister 100; however, it retains the small profile bolted joint to the canister shell as further described below. In addition, lid 220 of canister 200 has a different sealing arrangement. Referring now to FIGS. 15-25, canister 200 includes an elongated cylindrical body 203 comprising a single shell 206 including an open top 201, an open bottom 202, and sidewall 209 extending therebetween along a vertical longitudinal axis LA of the canister. Axis LA coincides with the geometric vertical centerline of the canister. Canister 200 further includes a bottom baseplate 210 and a top closure lid 220. In this finless embodiment of a shell 206, the baseplate preferably does not protrudes radially outwards beyond the lower portion of the shell to keep the outside diameter of the canister to a minimum for placement inside the outer radiation shielded overpack or cask 20. Shell 206 may be of monolithic unitary structure in one embodiment formed of a single material. Shell 206 further includes an inner surface 207 and opposing outer surface 208. A longitudinally-extending fuel cavity 205 extends between the top and bottom ends 201, 202 of the shell along longitudinal axis LA. Cavity 205 is similarly configured to that of canister 100 to hold a conventional fuel basket 60 comprising a prismatic array of longitudinally-extending fuel storage cells 62, as previously described herein. To structurally reinforce the canister shell 206 for the bolting, the top end 201 of shell 206 is radially thickened but in an inwards direction creates a uniform outer surface 208 but a step-shaped inner surface 207. This is dissimilar to shell 106 of canister 100 previously described herein which is radially thickened in an outward direction. Shell 206 therefore comprises an inwardly protruding annular mounting boss 232 integrally formed with the shell 206 at its top end 201. Boss 206 extends around the entire circumference of the upper portion of the shell. The boss defines top fastening portion 231 of the shell 206 having a greater transverse wall thickness T3 than the wall thickness T4 of the portions of the shell below between the bottom end 202 of the shell and the fastening portion 231. A plurality of upwardly open threaded bores 230 similar to bores 130 previously described herein are arranged and spaced circumferentially around the top end 201 of shell 206. Bores 230 penetrate upward facing annular end surface 211 of the shell. Referring particularly to FIGS. 23-25, the present lid 220 may have a stepped construction in one embodiment comprising a circular body including a top surface 221, bottom surface 222, an upper portion 223 adjacent the top surface, and a lower portion defining a radially protruding annular mounting flange 225 which is part of the bolted lid-to-shell joint. 124 adjacent the bottom surface, and in immediate portion 125. The mounting flange has an outside diameter D10 which is larger than outside diameter D11 of upper portion 223 of lower portion 124 and inside diameter D13 at the fastening portion 232 of shell 106. An annular step 270 is formed between the upper portion and mounting flange. Preferably, in one embodiment, diameter D10 is substantially the same as outside diameter D14 of the shell 206 such that flange 225 does not protrude substantially outwards beyond the shell in the radial direction. This advantageously maintains the narrow profile and dimensions of the canister 200 which keeps the inside diameter of the outer overpack or cask 20 as smaller as possible. The canister thus has an overall and collective diameter (i.e. D11 and D14) commensurate with existing SNF canisters having seal welded lids. The underside (i.e. downward facing surface) of mounting flange 225 defines an annular sealing surface 225-2 configured for positioning on the top end surface 211 of the shell when the lid is emplaced thereon (see, e.g. FIG. 24). The interface between the sealing surface 225-2 and end surface 211 is preferably one of flat-to-flat for accommodating annular outer seal 251. Seal 251 may be a planar self-energizing or raised face gasket in one embodiment that forms the outermost secondary confinement barrier to prevent gaseous products from leaking from the canister cavity 205 to the outer environment. Any suitable metallic or non-metallic seal material may be used. In the present lid 220 design, it bears noting that no portion of the lid protrudes downwards into the top portion of the canister cavity 205 in contrast to lid 120 previously described herein. Instead, a circular disk-shaped shield plate 260 is provided which sits immediately down and inside the top end of the cavity 205 as shown in FIGS. 23-24. The circumferential peripheral edge of the shield plate 260 is supported by an upward facing annular support surface 261 defined by an annular step-shaped shoulder formed in the upper inner surface 207a of shell 206 proximate to its top end 201, but spaced vertically downward therefrom as shown. The support surface 261 is thus formed in the radially thickened upper fastening portion 232 of the shell. Shield plate 260 forms part of the primary containment boundary of the canister 200. The shield plate may be sealed by an inner seal which may comprise a circular disk-shaped diaphragm seal 250 disposed between the shield and bottom surface 222 of the lid 200. Both the shield plate and diaphragm seal may be formed of a suitable metallic material, such as stainless steel in one embodiment. Canister 200 further includes Lid 120 further includes an annular step-shaped upper shoulder 127 at a transition between the intermediate mounting flange 1254 and upper portion 123, and an annular step-shaped lower shoulder 128 at a transition between mounting flange and the lower portion 124. Lower shoulder 128 engages the inside edge of the top end of the shell 106 inside cavity 105 at to center the lid on the shell. Lower shoulder 128 further provides a sealing interface, as further described herein. Mounting flange 125-1 comprises a plurality of longitudinal bolt through bores or holes 126 which extend completely through the flange. Bolt through holes 126 are configured for receiving the at least partially threaded shanks 127-1 of threaded fasteners which may be bolts 127 in one embodiment (see, e.g. FIGS. 10-12). Bolts 127 further have a diametrically enlarged tooling head 127-2 configured for engaging and applying a tool thereto to tighten or loosen the bolts. The underside of tooling heads 127-2 engage the upward facing surface of the mounting flange 125-1 (best shown in FIG. 11). Through holes 126 may be unthreaded in one preferred embodiment, but can be threaded in other embodiments. Top portion 123 may have any suitable outside diameter D6 which is smaller than diameter D5 of the intermediate portion 125/mounting flange 125-1 to provide access to the through holes 126 for inserting the bolts therethrough. FIGS. 23 and 24 shows the lid 220 fully seated, bolted, and sealed to the top fastening portion 232 of canister shell 106. The outer surface 225-1 of the mounting flange 225 of lid 220 does not project radially outwards beyond the outer surface 108 formed by the top fastening portion 231 defined by the annular mounting boss 232 of the shell. Accordingly, surfaces 125-1 and 208 lie in the same circular vertical plane Vp. Each mounting bolt 127 passes vertically through its respective bolt through hole 226 in the mounting flange 225 of the lid and directly threadably engages the shell via the threaded bores 230 formed through the upward facing annular end surface 211 at the top end 201 of the shell. Shield plate 260 is recessed in the top end 201 of shell 206 inside cavity 205 such that the top surface of the shield plate does not protrude upwards beyond the top end 201 of the shell. The inner diaphragm seal 250 lies in the same horizontal sealing plane as the outer annular seal 251. Special spatial relationships are created by the present lid 220 as shown in FIG. 24 to maintain the compact lid and canister profiles. The radial distance R10 between the longitudinal axis LA of canister 200 and bolt axes BA/bolt circle BC is less than both the radial distance R11 between outer surface 208 of shell 206 and axis LA, and radial distance R13 between outer surface 225-1 of lid mounting flange 225 and axis LA. R13 and R11 may be substantially the same providing a flush lid to shell transition and outer surfaces. Radial distance Radial distance R10 may be substantially the same are radial distance R12 between axis LA and the lower inner surface 207b of shell 206. While the foregoing description and drawings represent some example systems, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope and range of equivalents of the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. In addition, numerous variations in the methods/processes described herein may be made. One skilled in the art will further appreciate that the invention may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being defined by the appended claims and equivalents thereof, and not limited to the foregoing description or embodiments. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.
	claims	1. A collimator for a computed x-ray tomography imaging device, comprising a first grating and a second grating positioned on opposing sides of a primary radiation delivery window, the first and second gratings being part of separate first and second leaves, each of the first and second gratings comprising a plurality of attenuating members with a plurality of secondary radiation delivery windows extending between adjacent attenuating members of the first grating and the second grating, respectively, and wherein a width of each attenuating member is proportional to a distance between the attenuating member and the primary window. 2. The collimator of claim 1, wherein a width of each secondary window is less than a width of the primary window. 3. The collimator of claim 1, wherein a total area of each of the plurality of secondary windows is less than a total area of the primary window. 4. The collimator of claim 1, wherein a width of each secondary window is proportional to a distance between the secondary window and the primary window. 5. The collimator of claim 4, wherein the width of each secondary window is linearly proportional to the distance between the secondary window and the primary window. 6. The collimator of claim 1, wherein the width of each attenuating member is linearly proportional to the distance between the attenuating member and the primary window. 7. The collimator of claim 1, wherein the secondary windows comprise open passages extending through the grating. 8. The collimator of claim 1, wherein the secondary windows comprise panes of substantially radio-transmissive material. 9. The collimator of claim 1, wherein the attenuating members are oriented generally parallel to sides of the primary window. 10. The collimator of claim 1, wherein the secondary windows are oriented generally parallel to sides of the primary window. 11. The collimator of claim 1, wherein the first grating is movable relative to the second grating. 12. The collimator of claim 11, wherein the first and second gratings are independently movable. 13. A method of directing radiation during computed tomography (CT) imaging, comprising:emitting x-ray radiation from a radiation source toward an object;passing a first portion of the radiation through a primary window toward a target region in the object;passing a second portion of the radiation through at least one secondary window, on each of opposing sides of the primary window, to corresponding regions in the object outside the target region, where a width of each secondary window is less than a width of the primary window, rotating the radiation source and the primary and secondary windows about an axis, and translating the secondary windows relative to the primary window in a direction non-parallel to the axis;attenuating, between the primary and secondary windows, at least a third portion of the radiation; andgenerating CT image data based on the first and second portions of the radiation. 14. The method of claim 13, further comprising rotating the radiation source and the primary and secondary windows about an axis, and wherein radiation is passed through the primary window and the secondary windows while either (i) centers of the primary window and at least two of the secondary windows lie in a plane non-parallel to the axis or (ii) a plane intersecting the centers and the axis is non-parallel to the axis. 15. The method of claim 13, wherein the secondary windows are translated relative to the primary window during rotation of the radiation source. 16. The method of claim 15, wherein a first of the secondary windows is translated independently of a second of the secondary windows on an opposing side of the primary window from the first of the secondary windows. 17. The method of claim 13, wherein the attenuating comprises blocking passage of at least the third portion of the radiation between the primary and secondary windows. 18. A method of directing radiation during computed tomography (CT) imaging, comprising:emitting x-ray radiation from a radiation source toward an object;passing a first portion of the radiation through a primary window toward a target region in the object;passing a second portion of the radiation through at least one secondary window, on each of opposing sides of the primary window, to corresponding regions in the object outside the target region;attenuating, between the primary and secondary windows, at least a third portion of the radiation;rotating the radiation source and the primary and secondary windows about an axis, and translating the secondary windows relative to the primary window in a direction non-parallel to the axis; andgenerating CT image data based on the first and second portions of the radiation.
	claims	1. A method for automatically identifying geometric defects in turbine engine blades, comprising the steps of:acquiring one or more radiographic images corresponding to one or more turbine engine blades;identifying one or more regions of interest in the one or more radiographic images;extracting one or more geometric features of the turbine engine blade located in the one or more regions of interest; andanalyzing the one or more geometric features to identify one or more geometric defects present in the one or more geometric features of the turbine engine blades,wherein analyzing the one or more geometric features is not dependent on a set statistical parameters or a reference image. 2. The method of claim 1, wherein identifying the one or more regions of interest comprises generating an edge image corresponding to one or more cooling channels in the turbine engine blades, from the one or more radiographic images. 3. The method of claim 2, wherein the edge image is generated using a laplacian edge detection technique. 4. The method of claim 2, wherein identifying the one or more regions of interest further comprises automatically extracting a trailing edge region corresponding to the turbine engine blade, from the edge image. 5. The method of claim 4, wherein extracting the one or more geometric features of the turbine engine blade located in the one or more regions of interest further comprises segmenting one or more trailing edge holes along the trailing edge region of the turbine blade. 6. The method of claim 5, wherein the one or more geometric features are extracted using a plurality of techniques selected from the group consisting of connected components, centroid computation, outlier elimination, hough transforms, second derivative profiles and anisotropic diffusion. 7. The method of claim 5, further comprising applying at least one of a turbine engine blade acceptance criterion and a turbine engine blade rejection criterion based on the one or more extracted geometric features, to identify the one or more geometric defects in the turbine engine blades. 8. The method of claim 7, further comprising classifying one or more of the geometric defects in the turbine blade based on the extracted geometric features and at least one of the turbine engine blade acceptance criterion and the turbine engine blade rejection criteria. 9. The method of claim 8, wherein the one or more geometric defects comprise least one of missing holes, dwells, overdrills, merges, misdrills and scarfs in the cooling holes of the turbine blades. 10. The method of claim 9, wherein at least one of the scarfs and dwells are identified using relative contrast measures. 11. The method of claim 1, wherein the radiographic images are acquired using an X-ray imaging system. 12. A system for automatically identifying geometric defects in turbine engine blades comprising:a feature segmentation component configured to identify one or more regions of interest in one or more radiographic images corresponding to one or more turbine engine blades;a feature identification component configured to extract one or more geometric features of the turbine engine blade located in the one or more regions of interest; anda defect identification component configured to analyze the one or more geometric features to identify one or more geometric defects present in the one or more geometric features of the turbine engine blades, wherein said analysis is not dependent on statistical parameters or reference image. 13. The system of claim 12, wherein the one or more radiographic images are acquired using an X-ray imaging system. 14. The system of claim 12, wherein the feature segmentation component is configured to generate an edge image corresponding to one or more cooling channels in the turbine engine blades, from the one or more radiographic images. 15. The system of claim 14, wherein the feature segmentation component is further configured to automatically extract a trailing edge region corresponding to the turbine engine blade, from the edge image. 16. The system of claim 15, wherein the feature identification component is further configured to segment one or more trailing edge holes along the trailing edge region of the turbine blade. 17. The system of claim 12, wherein the feature identification component is configured to extract the one or more geometric features using a plurality of techniques selected from the group consisting of connected components, centroid computation, outlier elimination, hough transforms, second derivative profiles and anisotropic diffusion. 18. The system of claim 16, wherein the defect identification component is configured to apply at least one of a turbine engine blade acceptance criterion and a turbine engine blade rejection criterion based on the one or more extracted geometric features, to identify the one or more geometric defects in the turbine engine blades. 19. The system of claim 18, wherein the defect identification component is configured to classify the one or more geometric defects in the turbine blade based on the extracted geometric features and at least one of the turbine engine blade acceptance criterion and the turbine engine blade rejection criteria. 20. The system of claim 19, wherein the one or more geometric defects comprise least one of missing holes, dwells, overdrills, merges, misdrills and scarfs in the cooling holes of the turbine blades.
	abstract	A method of creating signage visible by infrared cameras and infrared weapon sights is provided. Particular application is made to the calibration of infrared weapon sights. An improved calibration target and method is developed.
	abstract	A method and system for managing a service level of a service provided by a service provider to a customer under a service level agreement. The actual measurement data is adjudicated to correct the measurement data in accordance with at least one adjudication element that provides information relating to how to correct the measurement data. The adjudicated measurement data is transformed into operational data by being reorganized into one or more groups of data. The operational data is evaluated by applying a formula to the operational data, resulting in the operational data being configured for being subsequently qualified. The operational data is qualified by comparing the evaluated operational data with specified service level targets for at least one service level period and identifying operational data points meeting and/or not meeting the specified service level targets.
043022960	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to sodium cooled pool-type nuclear reactors and, more particularly, to an arrangement for thermally isolating the hot sodium used in these reactors from the structural components of the reactor. 2. Description of the Prior Art Pool-type nuclear reactors are characterized by the placement of a reactor core, a main circulating pump and a main heat exchanger within a single primary system boundary which acts as a container. Typically these reactors are designed for use with liquid metal coolant and the primary system boundary or reactor vessel holds all of the components in a pool of sodium much like a large cup. Generally, in pool-type reactors, the coolant is pumped from a cold plenum through and into the core and is thereafter discharged into a hot plenum. From the hot plenum the coolant flows through the main heat exchangers and transfers the heat energy picked up in the reactor core to a secondary coolant. The primary coolant is thereafter discharged back into the cold plenum. The secondary coolant is pumped out of the reactor vessel and is used for power generation. In sodium cooled pool-type nuclear reactors there is a major design problem in isolating the pool of hot sodium from the load bearing, structural members of the reactor. Sodium cooled pool-type reactors are presently designed to operate with a hot plenum pool temperature in excess of 800.degree. F. and the design disclosed herein for a super-heated steam cycle operates with a hot pool temperature of 950.degree. F. These temperatures are all substantially above the nominal maximum design temperature of 800.degree. F. for stainless steel. Above this temperature stainless steel commences to creep and the reactor must be designed to thermally insulate the high temperature sodium from contacting the load bearing components of the reactor. Over the years there have been many solutions to this problem including the use of an insulated internal tank for separating the hot coolant in the hot plenum from the reactor vessel wall. In one existing pool reactor design a plenum separator in the form of a cylindrical shell is arranged to place low temperature sodium coolant in an annular region between the hot coolant and the reactor vessel wall. A portion of the flow from the main coolant pumps is diverted into the cylindrical shell and cold sodium is pumped past the reactor vessel wall and thereby cooling it. The present application relates to the application entitled "Plenum Separator System for Pool-Type Nuclear Reactors" by John E. Sharbaugh, Ser. No. 938,628, filed Aug. 31, 1978, and now abandoned. OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to thermally insulate the hot sodium present in a pool-type nuclear reactor from the load bearing structural components of the reactor. It is another object of the present invention to thermally insulate the hot sodium using a passive system that requires no auxiliary cooling and does not require a flow of primary coolant. It is a further object of the present invention to simplify the structure of the reactor, to reduce the orificing and distribution manifolds and to eliminate bypass flow around the primary heat exchangers. The foregoing and other objects are achieved by a flow isolated plenum for holding a stagnant quantity of sodium coolant in a pool-type nuclear reactor. The flow isolated plenum is located between the plenum holding the hot sodium and the structural members of the reactor. The flow isolated plenum forms a thermally insulating fluid barrier to the heat transfered from the hot sodium. Additional objects and features of the invention will appear from the following description in which the prefered embodiment has been set forth in detail in conjunction with the accompanying drawings.
048141380	description	Referring now to the figures of the drawings in detail and first, particularly, to FIGS. 1 and 2 thereof, there is seen a replacement rod which has a cladding tube 2 formed of a zirconium alloy, that is closed off at each end with respective end caps 3 and 4. The end caps 3 and 4 are welded to the jacket of the cladding tube 2 at weld points 5 and 6. Disposed in the cladding tube 2 is a sliding body 7 extending in the longitudinal direction of the cladding tube 2. The sliding body 7 is formed of two halves 7a and 7b which are held together by a cross pin 8. The long or longitudinal sides of the halves 7a and 7b facing one another have slotted links or detents 9a, 10a and 9b, 10b. The slotted links 9a and 10a of the half 7a are spaced apart from one another in the longitudinal direction of the cladding tube 2. The same applies for the slotted links 9b and 10b of the half 7b. A retaining spring 11 formed of a U-shaped leaf spring is disposed between the two halves 7a and 7b and each end is in the form of a respective cross member 11a, 11b. The cross member 11a engages the slotted links 9a and 9b, while the cross member 11b engages the slotted links 10a and 10b. The jacket of the cladding tube 2 is provided with an opening 12, in which the throat or bow of the retaining spring 11 formed of a U-shaped leaf spring can be engaged, so as to extend to the outside. A cross pin 13 is disposed between the two halves 7a and 7b, welded firmly to the jacket of the cladding tube 2 and guided with play through one end of the retaining spring 11. Thus the retaining spring 11 is fixed in the longitudinal direction of the cladding tube 2 by means of the cross pin 13. The sliding body 7 is provided with a two-part actuating rod 14 which is coaxial with the cladding tube 2. One part 14a of the actuating rod 14 is engaged in an opening in the end cap 3 of the replacement rod and is attached to one end of the sliding body 7. The other part 14b of the actuating rod 14 is engaged in an opening in the end cap 4 of the replacement rod and is attached to the other end of the sliding body 7. The actuating rod 14 is displaceable back and forth in the longitudinal direction of the cladding tube in the openings in the end caps 3 and 4. A helical spring 15 which is a compression spring seated on the part 14b of the actuating rod 14, has one end supported on the end cap 4 and another end supported on a support body 16 that is rigidly connected to the part 14b of the actuating rod 14. A steel sheath 17 is seated on the part 14b of the actuating rod 14 approximately midway between the support body 16 and the sliding body 7. The steel sheath rests on a retaining body 19 on the part 14b of the actuating rod 14 and is fixedly locked in detent fashion with a tongue 17a in the part 14b. Two tongue springs 18 in the form of locking devices are disposed on the end of the steel sheath 17 facing the sliding body 7 and the part 14a of the actuating rod 14 guided in the end cap 3. The two tongue springs 18 extend in the longitudinal direction of the actuating rod 14 and of the cladding tube 2, they are both the same length and are spaced apart from one another by an angle of 180.degree.. Thus the ends of the tongue springs 18 facing the end cap 4 are secured on the part 14b of the actuating rod 14, while the other ends of the tongue springs 18 facing the end cap 3 extending in the longitudinal direction of the cladding tube 2 tend to stand away from the shell surface of the part 14b of the actuating rod 14. Two sheaths 21 and 22 of a zirconium alloy are mutually spaced apart on the inside of the cladding tube 2 and firmly welded coaxially with the cladding tube 2. The part 14b of the actuating rod 14 is guided through the sheaths 21, 22. The sheath 21 at the end of the cladding tube 2 having the end cap 3 forms a locking shoulder protruding inward on the cladding tube 2, for the tongue springs representing the locking device. The tongue springs are capable of gripping the end of the sheath 21 facing the end cap 4, from behind. The sheath 22 forms a stop shoulder protruding inward from the cladding tube 2, for a clamping sheath 23 of a zirconium alloy, which is disposed coaxially between the sheaths 21 and 22 in such a way that it is displaceable back and forth in the longitudinal direction of the cladding tube 2 and is guided by the part 14b of the actuating rod 14 having the steel sheath 17. The inner shell surface of the clamping sheath 23 protrudes beyond the inner shell surface of the sheath 21 and hence beyond the locking shoulder associated with the tongue springs 18, in the radial direction. On the other hand, the inner shell surface of the clamping sheath 23 is also radially spaced apart from the part 14b of the actuating rod 14, by a distance somewhat greater than the thickness of the steel sheath 17 and the tongue springs 18. Furthermore, the distance by which the sheaths 21 and 22 forming the locking shoulder and the stop shoulder are spaced apart from one another in the longitudinal direction of the cladding tube 2 is greater than the sum of the length of the clamping sheath 23 and the length of the tongue springs 18 in the longitudinal direction of the actuating rod 14. FIG. 3 shows a holder basket 30 which is located under water in a fuel assembly or spent fuel pit. A nuclear reactor fuel assembly 31 is located in the holder basket with its base end facing up. The base piece of the fuel assembly has been removed from the base end. An irradiated fuel rod has also been removed from the fuel assembly 31 through gaps mutually aligned in spacers 32, using a fuel rod changing tool shown in German Published, Non-Prosecuted Application No. 26 35 501, because a spring that is intended for the force-locking retention of the fuel rod has broken off in the gap of one of the spacers 32. A force-locking connection is one which connects two elements together by force external to the elements, as opposed to a form-locking connection which is provided by the shapes of the elements themselves. A centering plate 33 has been attached on the holder basket 30 above the base end of the fuel assembly and a replacement rod shown in FIGS. 1 and 2 has been inserted through the centering plate into the empty aligned gaps of the spacers 32 of the nuclear reactor fuel assembly 31, using the fuel rod changing tool of German Published, Non-Prosecuted Application No. 26 35 501. An operator on a bridge 36 above the fuel assembly pit positions the replacement rod accurately in the nuclear reactor fuel assembly 31 with an actuating tool 35 shown in FIG. 3. The actuating tool 35 engages a suitable centering opening in the centering plate 33 and is suspended from a non-illustrated crane. The replacement rod is finally retained in a force-locking manner in the gap of the particular spacer 32 having the broken spring. As FIGS. 4-6 show, the actuating tool 35 has a bracket 37 on the upper end thereof, which is engaged by the nonillustrated crane. The bracket 37 is firmly screwed to a flange 38 which is located on the outer shell surface of an elongated base body 39. Coaxially disposed in the base body 39 is an elongated adjusting body 40, which is displaceable with respect to the base body 39 in the direction of the longitudinal axis. The elongated adjusting body 40 is secured against rotation about the longitudinal axis by a guide body 41 in the base body 39 and is provided with a transversely disposed stop pin 42, which limits the mobility of the adjusting body 40 in the longitudinal direction. A restoring spring in the form of a helical spring 43 is seated on the upper end of the adjusting body 40. The restoring spring is supported as a compression spring with one end on the base body 39 and with the other end on the adjusting body 40. The end of the adjusting body 40 having the restoring spring 43 is located inside a union nut 44. A thread 45 of the union nut 44 engages the base body 39 and the end of the adjusting body 40 rests on the bottom of the union nut 44. A pressure rod 46 which is displaceable in the longitudinal direction with respect to the adjusting body 40 is guided longitudinally by the adjusting body 40 coaxially with the adjusting body. The pressure rod 46 extends to the outside through an opening 47 engaged by the rod in the bottom of the union nut 44. A helical spring 48 acting as a restoring spring is seated on the pressure rod 46 inside the opening 47. The helical spring 48 is supported as a compression spring with one end on the union nut 44 and the other end on the pressure rod 46. As shown particularly clearly in FIG. 5, a two-part engaging bracket 50 for gripping the mushroom-shaped end-cap 3 of the replacement rod in the nuclear reactor fuel assembly 31 from behind, is disposed at the other end of the adjusting body 40. By turning the union nut 44 in one direction of rotation or the other under the influence of the restoring spring 43, the adjusting body 40 can be moved in the axial direction toward the end cap 3 for engaging it or away from the end cap 3 for releasing it, so that the two prestressed ends of the engagement bracket 50 spread apart. By displacing the pressure rod 46 in the axial direction toward the end cap 3 of the replacement rod, the actuating rod 14 can be pushed in the axial direction into the interior of the replacement rod, once the end cap 3 has been firmly engaged by the engaging bracket 50 by suitably turning the union nut 44. In the configuration shown on a larger scale in FIG. 6, in which the actuating tool 35 passes through and engages the centering plate 33 and the retaining bracket 50 firmly holds the end cap 3 of the replacement rod inserted into the spacers 32 of the fuel assembly 31, the pressure rod 46 is displaced toward the end cap 3 of the replacement rod at the handle 51 on the upper end of the pressure rod. In this way, the actuating rod 14 along with the sliding body 7 is also pushed into the cladding tube 2 of the replacement rod, and under the influence of the slotted links 9a, 9b and 10a, 10b the retaining spring 11 is pushed to the outside through the opening 12 in the cladding tube 2. As FIGS. 7 and 8 show, during this process the retaining spring 11 is advantageously disposed in a corner of a gap or opening in the spacer 32 in which a retaining spring 55, for example, that is located in the middle of one side of the gap, has broken. With the aid of four knobs 56 and 57, each two of which are located on a respective straight line parallel to the longitudinal direction of the gap in the middle of two adjacent sides of a gap, the replacement rod is then retained in the gap in a particularly stable and force-locking manner. In the right half of FIG. 9, an arrow 60 indicates the motion of the part 14b of the actuating rod 14 for expulsion of the retaining spring 11 from the cladding tube 2 of the replacement rod. During this motion of the part 14b, the tongue springs 18, which are secured with their ends facing in the direction of movement of the arrow 60 on the part 14b of the actuating rod 14, finally protrude with their other ends from the sheath 21 and spread the other ends to the outside. After relieving the pressure rod 46 of the actuating tube 35 and thus relieving the actuating rod 14 in the replacement rod as well, as shown in the left half of FIG. 9, the actuating rod 14 executes an opposite movement in the direction of an arrow 61 under the influence of the restoring spring 15, and finally the tongue springs 18 grip the sheath 21 in the replacement rod from behind, so that the expelled retaining spring 11 shown in FIGS. 7 and 8 locks in detent fashion in the position shown in FIGS. 7 and 8, and the replacement rod is retained in a force-locking manner in the gap in the spacer 32. The retaining bracket 50 of the actuating tool 35 can then be released from the end cap 3 under the influence of the restoring spring 43, by rotating the union nut 44 in the opposite direction and moving the adjusting body 40 away, and it can be lifted to the side using a non-illustrated crane. Finally, after lifting off the centering plate 33 on the nuclear reactor fuel assembly 31 in the fuel assembly holder basket 30, a base piece can be put back in place and the fuel assembly 31 can be reinserted into a nuclear reactor, once it has been pivoted along with the holder basket 30 by 180.degree. about an axis of rotation transverse to the longitudinal axis. The replacement rod of FIGS. 1 and 2 can also be released from the gap shown in FIGS. 7 and 8 with the actuating tool 35 of FIG. 4 shown in the position of FIG. 6. To this end, the pressure rod 46 and the actuating rod 14 are displaced back toward the end cap 3 in the longitudinal direction so that the tongue springs 18 shown in a locked position in the left half of FIG. 9 are unlocked, and in accordance with the direction of motion represented by the arrow 62 in the left half of FIG. 10 are displaced into the clamping sheath 23, which is hindered by the sheath 22 during this process from executing any motion in the longitudinal direction of the cladding tube 2 of the replacement rod. After the relief of the pressure rod 46 and thus of the actuating rod 14, the actuating rod 14 is moved in the opposite direction, as indicated by the arrow 63 in the right half of FIG. 10, under the influence of the restoring spring 15 in the replacement rod. In this case the tongue springs 18 carry the clamping sheath 23 along with them, because of their radially outwardly directed spring tension. The motion of the clamping sheath 23 in the longitudinal direction of the cladding tube 2 is finally terminated by the sheath 21, so that the clamping sheath 23 is stripped off by the tongue springs 18, and the tongue springs 18 are displaced into the sheath 21, into the initial position shown in the right half of FIG. 9, in which the retaining spring 11 of the replacement rod has also been pushed back into the cladding tube 2. The foregoing is a description corresponding in substance to German Application No. P 36 22 852.4, dated July 8, 1986, the International priority of which is being claimed for the instant application, and which is hereby made part of this application. Any material discrepancies between the foregoing specification and the aforementioned corresponding German application are to be resolved in favor of the latter.
	claims	1. A method for performing electrochemical phase transfer, the method comprising:flowing a solution of 18F− ions in H2O between first and second elongate electrodes, wherein at least one of the first or second elongate electrodes is formed from a blend of polymeric material and carbon particles;applying a potential between the first and second elongate electrodes to trap 18F− ions on the positively-charged one of the first and second elongate electrodes;reversing the potential between the first and second elongate electrodes;flowing a solvent between the first and second elongate electrodes while reversing the potential between the first and second elongate electrodes; andgradually heating the electrode on which the 18F− ions were trapped while applying the potential between the first and second elongate electrodes. 2. The method of claim 1, wherein the carbon particles in the first and second elongate electrodes are formed from glassy carbon. 3. The method of claim 1, further comprising removing the H2O from between the first and second elongate electrodes after flowing the solvent between the first and second elongate electrodes. 4. The method of claim 1, wherein the potential is 10 volts or less. 5. The method of claim 1, wherein flowing the solution between the first and second elongate electrodes includes flowing the solution in a flow path defined by a planar gasket disposed between the first and second elongate electrodes. 6. The method of claim 1, wherein flowing the solution between the first and second elongate electrodes includes flowing the solution in a serpentine shaped flow path between the first and second elongate electrodes. 7. The method of claim 1, wherein flowing the solution between the first and second elongate electrodes includes flowing the solution in a flow path sandwiched between the first and second elongate electrodes oriented parallel to each other. 8. The method of claim 1, wherein flowing the solution between the first and second elongate electrodes includes flowing the solution in a flow path between the first and second elongate electrodes that are oriented co-planar with respect to each other. 9. The method of claim 1, wherein flowing the solution between the first and second elongate electrodes includes flowing the solution in a flow path that outwardly tapers with respect to a flow direction of the solution in the flow path. 10. The method of claim 1, wherein the potential is 5 volts or less. 11. The method of claim 10, wherein flowing the solution between the first and second polymer-carbon electrodes includes flowing the solution in a flow path defined by a planar gasket disposed between the first and second polymer-carbon electrodes. 12. The method of claim 10, wherein flowing the solution between the first and second polymer-carbon electrodes includes flowing the solution in a serpentine shaped flow path between the first and second polymer-carbon electrodes. 13. The method of claim 10, wherein flowing the solution between the first and second polymer-carbon electrodes includes flowing the solution in a flow path sandwiched between the first and second polymer-carbon electrodes oriented parallel to each other. 14. A method comprising:flowing a solution of 18F− ions in water between first and second polymer-carbon electrodes;trapping 18F− ions on the first polymer-carbon electrode by applying a potential between the first and second polymer-carbon electrodes;releasing at least some of the 18F− ions from the first polymer-carbon electrode by reversing the potential between the first and second polymer-carbon electrodes; andextracting the at least some of the 18F− ions released from the first polymer-carbon electrode by flowing a solvent between the first and second polymer-carbon electrodes while reversing the potential between the first and second polymer-carbon electrodes. 15. The method of claim 14, further comprising heating the first polymer-carbon electrode while applying the potential between the first and second polymer-carbon electrodes. 16. The method of claim 14, wherein the first and second polymer-carbon electrodes are formed from a blend of polymeric material and carbon particles. 17. The method of claim 16, wherein the carbon particles in the first and second polymer-carbon electrodes are formed from glassy carbon. 18. The method of claim 14, further comprising removing the water from between the first and second polymer-carbon electrodes after flowing the solvent between the first and second elongate electrodes. 19. A method comprising:flowing a solution of 18F− ions in water along a serpentine shaped flow path disposed between first and second electrodes;applying a potential between the first and second electrodes to collect 18F− ions on the first electrode;changing the potential between the first and second electrodes to release at least some of the 18F− ions from the first electrode; andextracting the at least some of the 18F− ions released from the first electrode by flowing a solvent between the first and second electrodes while changing the potential between the first and second electrodes. 20. The method of claim 19, wherein the first and second electrodes are co-planar and flowing the solution includes flowing the solution in the serpentine shaped flow path that is disposed in a common plane as the first and second electrodes.
051270285	claims	1. A Bragg diffractor for energetic radiation comprising: a diffracting structure means having doubly curved diffracting planes and a diffracting surface comprising a plurality of steps with surfaces parallel to said diffracting planes; said steps being configured so that the midpoint on the curved surface of each step intercepts the focal circle of a Johansson geometry relating positions of a radiation source, the diffractor and a radiation image point; the surfaces of the said steps having a curvature in the plane of the focal circle equal to twice the radius of the focal circle and the surfaces of the said steps having a curvature perpendicular to the plane of the focal circle corresponding to rotational symmetry about a line passing through the source and image points. 2. A Bragg diffractor as defined in claim 1 in which the diffracting planes comprise the atomic planes of doubly curved single crystal lamellae. 3. A Bragg diffractor as defined in claim 1 in which the diffracting planes are the atomic planes of pieces of doubly-deformed single crystal material affixed to the doubly-curved surface of the steps on a substrate, each of the said pieces having a size equal to the size of the corresponding step. 4. A Bragg diffractor as defined in claim 1 in which the diffracting planes comprise the atomic planes of flakes or grains of single crystal nature affixed to the doubly curved surfaces of steps on a substrate. 5. A Bragg diffractor as defined in claim 1 in which the diffracting planes comprise alternating layers of different x-ray scattering power obtained by sequential deposition of these layers on the doubly curved surfaces of steps on a substrate. 6. A Bragg diffractor for energetic radiation comprising: a diffracting structure means having doubly curved diffracting planes and a diffracting surface comprising a plurality of steps with surfaces parallel to said diffracting planes; said steps being configured so that a point on the curved surface of each step intercepts the focal circle of a Johansson geometry relating positions of a radiation source, the diffractor and a radiation image point for all radial planes about an axis of symmetry; the surfaces of the said steps having a curvature in the plane of the focal circle equal to twice the radius of the focal circle, and the surfaces of the said steps having a curvature perpendicular to the plane of the focal circle corresponding to rotational symmetry about a line passing through the source and image points. 7. A Bragg diffractor as defined in claim 6 in which the diffracting planes comprise the atomic planes of doubly bent single crystal lamellae. 8. A Bragg diffractor as defined in claim 6 in which the diffracting planes are the atomic planes of pieces of toroidally-curved single crystal material affixed to the doubly-curved surfaces of the steps on a substrate, each of the said pieces having a size equal to the size of the corresponding step. 9. A Bragg diffractor as defined in claim 6 in which the diffracting planes comprise the atomic planes of flakes or grains of single crystal nature affixed to the doubly curved surfaces of steps on a substrate. 10. A Bragg diffractor as defined in claim 6 in which the diffracting planes comprise alternating layers of different x-ray scattering power obtained by sequential deposition of these layers on the doubly curved surfaces of steps of a substrate. 11. A Bragg diffractor for energetic radiation comprising: a diffracting structure means having doubly curved diffracting planes and a diffracting surface comprising a plurality of steps with surfaces parallel to said diffracting planes; said steps being configured so that a point on the curved surface of each step intercepts the focal circle of a Johansson geometry relating positions of a radiation source, the diffractor and a radiation focus; the surfaces of the said steps having a curvature in the plane of the focal circle equal to twice the radius of the focal circle; the surfaces of the steps having a curvature perpendicular to the plane of the focal circle corresponding to rotational symmetry about a line passing through a point on the focal circle. 12. A Bragg diffractor as defined in claim 11 in which the point through which the axis of rotational symmetry passes is a point on the focal circle diametrically opposite the midpoint of the diffractor. 13. A Bragg diffractor as defined in claim 11 in which the diffracting planes comprise the atomic planes of doubly curved single crystal lamellae. 14. A Bragg diffractor as defined in claim 11 in which the diffracting planes are the atomic planes of a pieces of doubly-curved single crystal material affixed to the doubly-curved surfaces of the steps on a substrate, each of the said pieces having a size equal to the size of the corresponding step. 15. A Bragg diffractor as defined in claim 11 in which the diffracting planes comprise the atomic planes of flakes or grains of single crystal nature affixed to the doubly curved surfaces of steps on a substrate. 16. A Bragg diffractor as defined in claim 11 in which the diffracting planes comprise alternating layers of different x-ray scattering power obtained by sequential deposition of these layers on the doubly curved surfaces of steps on a substrate.
	claims	1. An apparatus including an automated X-ray imaging system for producing a plurality of X-ray imaging signals, comprising:an X-ray emission system responsive to at least one emission control signal by providing at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics;an X-ray detection system responsive to at least one detection control signal and for placement in relation to said X-ray emission system to be responsive to at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems by providing corresponding first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively; anda control system, coupled to said X-ray emission and detection systems, responsive to said first and second image signals by providing said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively; whereinsaid portion of said subject defines a target region for said at least respective portions of said first and second doses of X-ray radiation,said target region is disposed in a first spatial relation to said X-ray emission system,said target region is disposed in a second spatial relation to said X-ray detection system, andsaid X-ray emission system is further responsive to said at least one emission control signal by controlling said first spatial relation. 2. An apparatus including an automated X-ray imaging system for producing a plurality of X-ray imaging signals, comprising:an X-ray emission system responsive to at least one emission control signal by providing at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics;an X-ray detection system responsive to at least one detection control signal and for placement in relation to said X-ray emission system to be responsive to at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems by providing corresponding first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively; anda control system, coupled to said X-ray emission and detection systems, responsive to said first and second image signals by providing said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively; whereinsaid portion of said subject defines a target region for said at least respective portions of said first and second doses of X-ray radiation,said target region is disposed in a first spatial relation to said X-ray emission system,said target region is disposed in a second spatial relation to said X-ray detection system, andsaid X-ray detection system is further responsive to said at least one detection control signal by controlling said second spatial relation. 3. An apparatus including an automated X-ray imaging system for producing a plurality of X-ray imaging signals, comprising:an X-ray emission system responsive to at least one emission control signal by providing at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics;an X-ray detection system responsive to at least one detection control signal and for placement in relation to said X-ray emission system to be responsive to at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems by providing corresponding first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively; anda control system, coupled to said X-ray emission and detection systems, responsive to said first and second image signals by providing said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively; whereinsaid portion of said subject defines a target region for said at least respective portions of said first and second doses of X-ray radiation,said target region is disposed in a first spatial relation to said X-ray emission system,said target region is disposed in a second spatial relation to said X-ray detection system,said X-ray emission system is further responsive to said at least one emission control signal by controlling said first spatial relation, andsaid X-ray detection system is further responsive to said at least one detection control signal by controlling said second spatial relation. 4. An apparatus including an automated X-ray imaging system for producing a plurality of X-ray imaging signals, comprising:an X-ray emission system responsive to at least one emission control signal by providing at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics, and said X-ray emission system includesan X-ray source responsive to a first portion of said at least one emission control signal by providing X-ray radiation with at least one of said plurality of X-ray radiation characteristics corresponding to said first portion of said at least one emission control signal, anda collimator coupled to said X-ray source and responsive to a second portion of said at least one emission control signal by conveying said X-ray radiation with at least another of said plurality of X-ray radiation characteristics corresponding to said second portion of said at least one emission control signal;an X-ray detection system responsive to at least one detection control signal and for placement in relation to said X-ray emission system to be responsive to at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems by providing corresponding first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively; anda control system, coupled to said X-ray emission and detection systems, responsive to said first and second image signals by providing said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively. 5. A automated method for producing a plurality of X-ray imaging signals corresponding to selected views of a subject with selectively variable image resolutions, comprising:receiving at least one emission control signal;generating, in response to said at least one emission control signal, at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics, by generating with an X-ray emission system, in response to said at least one emission control signal, at least first and second doses of X-ray radiation;receiving at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject by receiving with an X-ray detection system at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems, wherein said portion of said subject defines a target region for said at least respective portions of said first and second doses of X-ray radiation;receiving at least one detection control signal;generating, in response to said at least one detection control signal and said at least respective portions of said first and second doses of X-ray radiation, first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively;processing said first and second image signals;generating, in response to said processed first and second image signals, said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively;disposing said target region in a first spatial relation to said X-ray emission system;disposing said target region in a second spatial relation to said X-ray detection system; andcontrolling said first spatial relation in further response to said at least one emission control signal. 6. A automated method for producing a plurality of X-ray imaging signals corresponding to selected views of a subject with selectively variable image resolutions, comprising:receiving at least one emission control signal;generating, in response to said at least one emission control signal, at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics, by generating with an X-ray emission system, in response to said at least one emission control signal, at least first and second doses of X-ray radiation;receiving at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject by receiving with an X-ray detection system at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems, wherein said portion of said subject defines a target region for said at least respective portions of said first and second doses of X-ray radiation;receiving at least one detection control signal;generating, in response to said at least one detection control signal and said at least respective portions of said first and second doses of X-ray radiation, first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively;processing said first and second image signals;generating, in response to said processed first and second image signals, said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively;disposing said target region in a first spatial relation to said X-ray emission system;disposing said target region in a second spatial relation to said X-ray detection system; andcontrolling said second spatial relation in further response to said at least one detection control signal. 7. A automated method for producing a plurality of X-ray imaging signals corresponding to selected views of a subject with selectively variable image resolutions, comprising:receiving at least one emission control signal;generating, in response to said at least one emission control signal, at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics, by generating with an X-ray emission system, in response to said at least one emission control signal, at least first and second doses of X-ray radiation;receiving at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject by receiving with an X-ray detection system at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject disposed substantially between said X-ray emission and detection systems, wherein said portion of said subject defines a target region for said at least respective portions of said first and second doses of X-ray radiation;receiving at least one detection control signal;generating, in response to said at least one detection control signal and said at least respective portions of said first and second doses of X-ray radiation, first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively;processing said first and second image signals;generating, in response to said processed first and second image signals, said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively;disposing said target region in a first spatial relation to said X-ray emission system;disposing said target region in a second spatial relation to said X-ray detection system;controlling said first spatial relation in further response to said at least one emission control signal; andcontrolling said second spatial relation in further response to said at least one detection control signal. 8. A automated method for producing a plurality of X-ray imaging signals corresponding to selected views of a subject with selectively variable image resolutions, comprising:receiving at least one emission control signal;generating, in response to said at least one emission control signal, at least first and second doses of X-ray radiation, wherein said second dose differs from said first dose in one or more of a plurality of X-ray radiation characteristics, bygenerating, in response to a first portion of said at least one emission control signal, X-ray radiation with at least one of said plurality of X-ray radiation characteristics corresponding to said first portion of said at least one emission control signal, andcollimating, in response to a second portion of said at least one emission control signal, said X-ray radiation;receiving at least respective portions of said first and second doses of X-ray radiation following exposure thereto of at least a portion of a subject;receiving at least one detection control signal;generating, in response to said at least one detection control signal and said at least respective portions of said first and second doses of X-ray radiation, first and second image signals corresponding to said respective portions of said first and second doses of X-ray radiation, respectively;processing said first and second image signals; andgenerating, in response to said processed first and second image signals, said emission and detection control signals, wherein said second image signal differs from said first image signal in one or more of a plurality of image characteristics, and said first and second image signals together form a plurality of images which is one or more ofa planar image and a volumetric image, respectively,a volumetric image and a planar image, respectively,a lower resolution image and a higher resolution image, respectively, anda higher resolution image and a lower resolution image, respectively. 9. The method of claim 8, wherein said generating, in response to said at least one detection control signal and said at least respective portions of said first and second doses of X-ray radiation, first and second image signals comprises generating, in response to a first portion of said at least one detection control signal, a plurality of pixel signals. 10. The method of claim 9, wherein said generating, in response to said at least one detection control signal and said at least respective portions of said first and second doses of X-ray radiation, first and second image signals further comprises processing said plurality of pixel signals to generate said first and second image signals.
040653510	summary	BACKGROUND OF THE INVENTION In the field of physics it is desirable to inject high energy particles into a toroidal container to produce colliding beams, and reaction products from reactions that convert one form of energy into another, such reactions being described in "Controlled Thermonuclear Reactions," by Glasstone and Lovberg, 1960, which is incorporated by reference herein, but the systems known heretofore were limited to low density beams, and correspondingly low reaction rates, or they required large and cumbersome apparatus, or were otherwise ineffective, inefficient or troublesome. SUMMARY OF THE INVENTION This invention provides a poloidal divertor for stacking counterstreaming ion beams to provide high intensity colliding beams. To this end apparatus and method are provided that injects opposing, neutral, high energy, high velocity, ordered, atomic deuterium and tritium beams into a lower energy, neutral, toroidal, thermal equilibrium, target plasma that is magnetically confined in a vacuum tight toroidal housing along an endless magnetic axis by a strong restoring force magnetic field having helical field lines. The plasma converts the neutral beams into thermal electrons and stacked ions that drift along the helical magnetic field lines as stacked, counterstreaming deuteron and triton beams that collide head-on all along the magnetic axis, while the poloidal divertor removes thermal ions and electrons in equal numbers to balance the injection rate. By confining the plasma in a strong restoring force toroidal magnetic having a poloidal divertor, the counterstreaming ion beams are confined and stacked at high densities for up to 1 or 2 density-confinement times, or more, for producing high reaction rates all along an endless magnetic axis. Moreover, large numbers of useful reaction products are produced all along the toroidal target plasma column, and these products can be removed, captured, or used in a conventional manner. In one embodiment, this invention provides apparatus and method for injecting high energy, atomic deuterium and tritium beams into a confining magnetic field containing a lower energy, neutral, toroidal, thermal equilibrium target plasma, comprising vacuum container means having an endless first axis, vacuum pump means and entrance and exit port means communicating with the inside of the container means; means for forming a strong restoring force confining magnetic field having helical field lines forming inner and outer concentric magnetic surfaces centered on an extended magnetic second axis concentric with the first axis in the container means; means for forming an equilibrium, thermal, target plasma column of disassociated electrons, tritons and deuterium ions that are confined by the magnetic field in said column in the container means along the endless magnetic axis at an elevated temperature that causes the ions to diffuse by collisions outwardly away from the magnetic axis toward the vacuum container means; means for continuously injecting neutral atomic beams of deuterium and tritium through the entrance ports to produce thermal electrons and counterstreaming deuterons and tritons in the plasma column along the magnetic axis at energies above the energy of the target plasma; the injection forming ordered, high energy, stacked, high velocity, counterstreaming, deuterons and tritons that circulate along the helical field lines with distinct ion velocity distributions that are oppositely displaced in velocity along the magnetic axis while the helical field lines provide strong restoring forces that maintain the directedness of the fast deuterons and tritons along the magnetic axis until they slow down to the average energy of the confined neutral, thermal, target plasma column, thereby to maintain the plasma temperature by stacking the counterstreaming beams for many orbits around the length of the axis at a rate in balance with the diffusion rate; and divertor means communicating with the field lines of the outer magnetic surfaces having vacuum pumping means for collecting diffusing thermal plasma particles through the exit ports and burying them as they diffuse outwardly from the magnetic axis so as to maintain high counterstreaming fast deuteron and triton number densities and balanced thermal diffusion and injections rates. OBJECTS OF THE INVENTION It is an object of this invention, therefore, to provide a means and method for injecting neutral atomic beams of tritium and deuterium into a magnetically confined equilibrium target plasma column along trajectories that produce high energy, high velocity, ordered, counterstreaming deuterons and tritons along the magnetic axis at a high energy above the energy of the target plasma column.
	description	The present invention relates generally to particle beam targets utilized for producing radionuclides. More particularly, the present invention relates to the cooling of targets during irradiation by a particle beam. Radionuclides may be produced by bombarding a target with an accelerated particle beam as may be generated by a cyclotron, linear accelerator, or the like. The target contains a small amount of target material that is typically provided in the liquid phase but could also be a solid or gas. The target material includes a precursor component that is synthesized to the desired radionuclide in reaction to irradiation by the particle beam. As but one example, F-18 ions may be produced by bombarding a target containing water enriched with the 0-18 isotope with a proton beam. After bombardment, the as-synthesized F-18 ions may be recovered from the water after removing the water from the target. The production of F-18 ions in particular has important radiopharmaceutical applications. For instance, the as-produced F-18 ions may be utilized to produce the radioactive sugar fluorodeoxyglucose (2-fluoro-2-deoxy-D-glucose, or FDG), which is utilized in positron emission tomography (PET) scanning. PET is utilized in nuclear medicine as a metabolic imaging modality in the diagnosis of cancer. The production of radionuclides such as F-18 ions is an expensive process, and thus any improvement to the production efficiency and yield would be desirable. Unfortunately, the application of the particle beam initiates the desired nuclear reaction in only a very small fraction of the radionuclide precursors in the target. The particle beam deposits a significant amount of heat into the target material residing in the target during bombardment. For instance, in the conventional production of F-18 ions, it has been found that only about one of every 2,000 protons stopping in the target water actually produces the desired nuclear reaction, with the rest of the proton beam merely depositing heat. Yet the amount of radioactive product that can be produced in a radionuclide target is proportional to the amount of heat that can be removed during bombardment of the target material of choice. The heat energy deposited in the target material may cause boiling and generate bubbles or voids in the volume of target material. Bubbles or voids do not yield radionuclides; the particle beam simply passes through the bubbles or voids to the back of the target structure. Moreover, the rapidly increasing vapor pressure developed in the target chamber containing the target material as a result of the heat deposition may cause the target to structurally fail if the heat deposition is not adequately removed. Radionuclide production yield could be increased by increasing the beam energy inputted to the target, but due to the foregoing problems the beam energy has been intentionally limited in conventional systems. Conventional radionuclide production systems may provide a means for cooling the beam targets generally by routing a heat transfer medium such as water to the target to carry heat away therefrom during bombardment. Conventional target designs, however, do not have sufficient capacity for heat removal, and as a result the radionuclide production yield and efficiency has been less than desirable in conventional targets. In view of the foregoing, there is an ongoing need for beam targets utilized for radionuclide production that enable increased capacity and efficiency for removing heat and thus improved radionuclide production yield and efficiency. To address the foregoing problems, in whole or in part, and/or other problems that may have been observed by persons skilled in the art, the present disclosure provides methods, processes, systems, apparatus, instruments, and/or devices, as described by way of example in implementations set forth below. According to one implementation, a particle beam target includes a target body, a target cavity, a plurality of parallel grooves, a plurality of peripheral bores, and a plurality of radial outflow bores. The target body includes a front side, a back side and a lateral outer wall extending from the front side to the back side. The target cavity is disposed in the target body and includes a back inner wall, a lateral inner wall, and a cross-section bounded by the lateral inner wall. The back inner wall is spaced from the back side relative to a lateral axis, and the lateral inner wall extends from the back inner wall toward the front side generally along the direction of the lateral axis. The parallel grooves are formed in the back side. Each groove includes a first groove end and a second groove end and runs along a transverse direction from the first groove end to the second groove end, the transverse direction being orthogonal to the lateral direction. The peripheral bores extend through the target body from the plurality of grooves generally toward the front side. The peripheral bores are arranged to circumscribe the target cavity cross-section in proximity to the lateral inner wall, wherein each groove fluidly communicates with at least one peripheral bore at the first groove end and at least one other peripheral bore at the second groove end. The radial outflow bores extend in respective radial directions relative to the lateral axis from the plurality of peripheral bores to the lateral outer wall, each radial outflow bore fluidly communicating with at least one of the peripheral bores. The target body defines a plurality of liquid coolant flow paths. Each liquid coolant flow path runs from a respective groove to at least one of the first groove end and the second groove end of the respective groove, through at least one peripheral bore, through at least one radial outflow bore, and to the lateral outer wall. According to another implementation, method is provided for cooling a particle beam target. The particle beam target includes a target cavity for containing a target material and is capable of receiving a particle beam for producing radionuclides from the target material. In the method, a coolant is flowed to a back side of the particle beam target, the back side being opposite to a front side of the target at which the particle beam is received. The coolant is divided into a plurality of coolant input flows in a corresponding plurality of grooves disposed at the back side, the grooves running in a transverse direction. In each groove, the coolant input flow is split into a first transverse coolant flow path directed along the transverse direction toward a first groove end and a second transverse coolant flow path directed along an opposite transverse direction toward a second groove end. In each groove, the coolant in the first transverse coolant flow path is diverted into a peripheral bore and the second transverse coolant flow path is diverted into another peripheral bore. Each peripheral bore is part of a plurality of peripheral bores running from respective first or second groove ends toward the front side, and the plurality of peripheral bores circumscribe the target cavity. The coolant flows from each first transverse coolant flow path and second transverse coolant flow path into a corresponding lateral coolant flow path directed along a lateral direction generally orthogonal to the transverse direction. The coolant in the plurality of peripheral bores is diverted into a plurality of radial outflow bores located at an end of the peripheral bores opposite to the plurality of first groove ends and second groove ends along the lateral direction, wherein the coolant flows from each lateral coolant flow path into one of a plurality of radial coolant flow paths running through the respective radial outflow bores along a radial direction generally orthogonal to the lateral direction and directed away from the target cavity. While flowing the coolant through the plurality of first transverse coolant flow paths, second transverse coolant flow paths, lateral coolant flow paths and radial coolant flow paths, heat is removed from the target material contained in the target cavity. According to another implementation, a particle beam target includes a target body, a target cavity, a channel, a plurality of peripheral bores, and a plurality of radial outflow bores. The target body includes a front side, a back side, and a lateral outer wall extending from the front side to the back side. The target cavity is disposed in the target body and is bounded by a lateral inner wall of the target body. The lateral inner wall is disposed about a lateral axis and extends from a target cavity opening at the front side toward the back side. The channel is formed at the front side and circumscribes the target cavity opening. The peripheral bores extend through the target body from the back side toward the front side. The peripheral bores circumscribe the target cavity in proximity to the lateral inner wall, wherein the peripheral bores are arranged along a peripheral bore perimeter at a radial distance between the target cavity and the channel relative to the lateral axis. The radial outflow bores extend in respective radial directions relative to the lateral axis from the plurality of peripheral bores to the lateral outer wall. Each radial outflow bore fluidly communicates with at least one of the peripheral bores. The target body defines a plurality of liquid coolant flow paths, each liquid coolant flow path running through at least one peripheral bore, through at least one radial outflow bore, and to the lateral outer wall. According to another implementation, a particle beam target includes a target body, a target cavity, a plurality of peripheral bores, and a plurality of radial outflow bores. The target body includes a front side, a back side, and a lateral outer wall extending from the front side to the back side. The target cavity is disposed in the target body and is bounded by a lateral inner wall of the target body. The lateral inner wall is disposed about a lateral axis and extends from a target cavity opening at the front side toward the back side. The peripheral bores extend through the target body from the back side toward the front side and circumscribe the target cavity. The target body further includes an annular portion interposed between the lateral inner wall and the peripheral bores. The annular portion has a radial thickness between the lateral inner wall and the peripheral bores ranging from, for example, 0.002 inch to 0.5 inch. The radial outflow bores extend in respective radial directions relative to the lateral axis from the plurality of peripheral bores to the lateral outer wall. Each radial outflow bore fluidly communicates with at least one of the peripheral bores. The target body defines a plurality of liquid coolant flow paths, each liquid coolant flow path running through at least one peripheral bore, through at least one radial outflow bore, and to the lateral outer wall. According to another implementation, a particle beam target includes a target body, a target cavity, a target window, a plurality of peripheral bores, and a plurality of radial outflow bores. The target body includes a front side, a back side, and a lateral outer wall extending from the front side to the back side. The target cavity is disposed in the target body and is bounded by a lateral inner wall of the target body. The lateral inner wall is disposed about a lateral axis and extends from a target cavity opening at the front side toward the back side. The target window is disposed at the front side and covers the target cavity opening. The peripheral bores extend through the target body from the back side toward the front side. The peripheral bores circumscribe the target cavity in proximity to the lateral inner wall. The peripheral bores are arranged along a peripheral bore perimeter at a radial distance between the target cavity and an outer perimeter of the target window relative to the lateral axis. The radial outflow bores extend in respective radial directions relative to the lateral axis from the plurality of peripheral bores to the lateral outer wall. Each radial outflow bore fluidly communicates with at least one of the peripheral bores. The target body defines a plurality of liquid coolant flow paths, each liquid coolant flow path running through at least one peripheral bore, through at least one radial outflow bore, and to the lateral outer wall. Other devices, apparatus, systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. By way of example, FIGS. 1-13 illustrate various implementations of a target and associated radionuclide production apparatus or system. The various implementations provide a highly efficient solution for cooling a target cavity containing target material bombarded by particles (e.g., protons) for the purpose of obtaining a maximum amount of heat removal from the target material and thereby maximizing the amount of radioactive product that can be produced from that target material. As noted above, the amount of radioactive product that can be produced in a radionuclide target is proportional to the amount of heat that can be removed during bombardment of the target material of choice. In various implementations, a high rate of heat removal is accomplished at least in part by providing numerous individual, high-velocity, multi-stage coolant flow paths arranged in parallel and closely spaced to each other and in close proximity to the target cavity containing the target material to be cooled. This configuration maximizes the heat flow from the target medium to the coolant by minimizing the heat conduction distance (i.e., the thickness of the target structure across which the heat must be transferred). The target may be implemented in connection with any type of liquid coolant and any type of radionuclide synthesis process. A target consistent with the present teaching has experimentally demonstrated superior performance in transferring heat away from target material, as compared to conventional targets. FIG. 1 is a simplified schematic view of an example of a radionuclide production apparatus or system 100 as an example of an operating environment in which a target 102 according to the present teachings may be implemented. The target 102 generally includes a front side (beam input side) 112 at which a particle beam 114 is directed and a back side (coolant input side) 116 which, in the presently described implementation, receives an input of any suitable liquid coolant (e.g., water). The target 102 also generally includes a target body that may include one or more parts assembled together. Insofar as the target 102 may include assembled components, the target 102 may also be referred to herein as a target assembly. The target 102 is typically constructed from a suitable metal or metal alloy, a few examples being silver, aluminum, gold, nickel, titanium, copper, platinum, tantalum, niobium, and stainless steel. At the front side 112, the target 102 includes a target window 118 of any material suitable for transmitting the particle beam 114 therethrough while minimizing loss of beam energy. Typically, the target window 118 is constructed from a metal or metal alloy, a few examples being the commercially available HAVAR® alloy, titanium, tantalum, tungsten, and gold. The thickness of the target window 118 may range, for example, from 0.3 to 30 μm. A target chamber or cavity 120 is formed within the target body and defines an interior of the target body into which the particle beam 114 is directed via the target window 118. In practice, the target cavity 120 contains a flowable target material that includes a radionuclide precursor, the composition of which will depend on the type of radionuclide being synthesized. As a non-limiting example, the internal volume (or size) of the target cavity 120 may range from 1.0 to 10 cm3. A coolant inlet 122 and a coolant outlet 124 are also formed in the target body. The coolant inlet 122 and the coolant outlet 124 communicate with each other via a coolant flow system internal to the target body, as described in more detail below. In some non-limiting examples, particularly where the target material is a liquid, the volume of the target cavity 120 after assembly of the target window 118 thereto ranges from 0.5 cc (or ml) to 20 cc. In other non-limiting examples, particularly where the target material is a solid, the volume of the target cavity 120 after assembly of the target window 118 thereto ranges from 0.1 cc to 20 cc. In other non-limiting examples, particularly where the target material is a gas, the volume of the target cavity 120 after assembly of the target window 118 thereto ranges from 100 cc to 10,000 cc (10 L). One or more target material transfer bores may be formed in the target 102 for inputting target material into and/or outputting target material from the target cavity 120. In the present example, a target material inlet bore 132 and a separate target material outlet bore 134 are formed in the target body and fluidly communicate with the target cavity 120. The locations of the inlet bore 132 and the outlet bore 134 are arbitrary in the schematic view of the FIG. 1, and may depend on whether it is desired to load the target 102 with target material from the top or the bottom. For example, the inlet bore 132 may alternatively be located at the top of the target cavity 120 and the outlet bore 134 may be located at the bottom of the target cavity 120. As a further alternative, the target 102 may include a single bore 132 or 134 utilized for both introducing target material (including precursors) to the target cavity 120 and removing target material (including radionuclides) from the target cavity 120. The illustrated example, in which a single fluid transfer bore 132 or 134 or both an inlet bore 132 and an outlet bore 134 are utilized, is directed primarily to the use of a liquid target material. It will be appreciated by persons skilled in the art that in other cases, such as where the target material is a solid or a gas, the inlet bore 132 and/or outlet bore 134 may be modified as necessary or not utilized at all. As one example of the use of a solid target material, molten target material could first be loaded into the target cavity 120 and allowed to solidify, and the target material is maintained in the solid phase during application of the particle beam due to the cooling provided by the present teachings. The radionuclide production apparatus 100 includes a particle beam source 140 such as, for example, a cyclotron, a linear accelerator, or the like. The structure and operation of the particle beam source 140 may depend on the type of particle beam 114 utilized. As an example, the particle beam 114 may be a proton beam. The proton beam is typically applied at a beam power of about 0.5 kW or greater, up to a practical limit that avoids structural failure of the target 102 and impairment of the desired nuclear reaction. In conventional targets, the beam power typically does not exceed about 2 kW. In at least some implementations of the target 102 taught herein, it is expected that the beam power may be increased to about 10 kW or greater. The radionuclide production apparatus 100 also includes a target material transport circuit or system 150. The target material transport system 150 may include any suitable target material source (supply, reservoir, etc.) 152, a device for moving the target material such as, for example, a pump 154, and a target material input line 156 for conducting the target material from the target material source 152 to the inlet bore 132 and thus the target cavity 120. The target material transport system 150 may be implemented as a loop, in which case the above-noted outlet bore 134 is included as well as a target material output line 158 that leads back to the target material source 152 or at least back to the pump 154. By utilizing the loop configuration, the target material may be flowed through the inlet bore 132, filling the target cavity 120, and through the outlet bore 134 prior to activation of the particle beam 114. In this manner, the target material transport system 150 may be utilized to purge the target cavity 120 of bubbles, gases, contaminants, or any other undesired components prior to application of the particle beam 114 and ensuing synthesis. In practice, the target cavity 120 may be filled from the top (in which case the inlet bore 132 may be located at the top, as in the illustrated example) or from the bottom (in which case the inlet bore 132 may be located at the bottom). The schematically illustrated positions of the target material source 152 and the pump 154 may be switched as needed for top-filling or bottom-filling. In the present example, the target material transport system 150 may also be utilized to route as-produced radionuclides to a desired radionuclide destination 162 for further processing, such as a hot lab. For this purpose, a radionuclide output line 164 is schematically shown as fluidly communicating with the target material outlet line 158 (or, alternatively, with the target material inlet line 156). A valve or other controllable flow-diverting means (not shown) may serve as an interface between the target material transport system 150 and the radionuclide output line 164 for this purpose. The radionuclide production apparatus 100 also includes a coolant circulation circuit or system 170. The coolant circulation system 170 may include any suitable coolant conditioning apparatus (heat exchanger, condenser, evaporator, and the like) 172 for providing coolant to the target 102, receiving heated coolant from the target 102, removing heat from the heated coolant, and repeating the cycle as needed during synthesis. The coolant circulation system 170 may also include a device for moving the coolant to and from the target 102 such as, for example, a pump 174, a coolant input line 176 for conducting the coolant from the coolant conditioning apparatus 172 to the coolant inlet 122 of the target 102, and a coolant output line 178 for conducting the heated coolant from the coolant outlet 124 of target 102 back to the coolant conditioning apparatus 172. In practice, the target material source 152 is provided with a suitable supply of target material, and the target cavity 120 is loaded with a suitable amount of target material by flowing the target material from the target material source 152 into the target cavity 120. Once the target cavity 120 is filled (partially or entirely, depending on design) with a desired amount of target material, the particle beam source 140 is operated to generate a particle beam 114, which is directed into the target cavity 120 via the target window 118 for interaction with the target material. Application of the particle beam 114 results in synthesis of radionuclides from the target material in the target cavity 120. After a sufficient amount of time during the “beam-on” stage has elapsed, the particle beam 114 is switched off and the as-produced radionuclides are transported to the hot lab or other destination 162 for further processing. As noted above, during application of the particle beam 114, a large amount of energy is deposited as heat in the target material residing in the target cavity 120. This heat generates a large amount of vapor within the target cavity 120 resulting in voids or bubbles within the target material. The voids or bubbles interfere with the particle beam's ability to cause the nuclear reaction needed for radionuclide synthesis, and the vapor pressure may quickly cause the target 102 to fail structurally. Hence, the heat must be rapidly removed from the target 102 and from the target material residing in the target 102. This is accomplished through the operation of the coolant circulation system 170 during application of the particle beam 114 in conjunction with a coolant circulation system incorporated into the target 102, as described by way of examples below. A non-limiting example of radionuclide synthesis is the production of the F-18 (18F) ion (fluorine-18) from the O-18 (oxygen-18) precursor. In this case, the target material may be provided as O-18 enriched water, i.e., water in which a desired fraction has the composition H218O, and the particle beam is a proton beam. The nuclear reaction is specified as 18O(p,n)18F. Other examples of radionuclides that may be produced include, but are not limited to, N-13, O-15, and C-11. N-13 is produced from natural water as the target material utilizing alpha-particles according to the nuclear reaction 16O(p,α)13N. The target 102 disclosed herein is particularly suited for use as a “batch” or “static” target. In a batch or static target, the target material is loaded in the target cavity 120, the same amount of target material remains in the target cavity 120 during synthesis, and the target material (now including radionuclides) is thereafter removed from the target 102. An alternative type of target is a recirculating target, in which the target material is circulated through the target cavity 120 during application of the particle beam. In a recirculating target, the target material itself may be utilized as a heat transfer medium to some degree because the target material carries heat away from the target and, prior to being recirculated back to the target, may be cooled by a heat exchange system located remotely from and external to the target body. The present teachings, however, encompass the use of the target 102 disclosed herein as a recirculating target as an option for increasing the heat-removal capacity of the recirculating target. FIG. 2 is a side, partially cut-away view of an example of a target 200 according to the present teachings, and FIG. 3 is a perspective view from the back side. The target 200 may be utilized in a radionuclide production system such as illustrated by example in FIG. 1, or in other, differently configured radionuclide production systems. The target 200 includes a target body 202 that may be mounted in a recess of a front target section 204. A target cavity and various coolant passages defining a plurality of coolant paths (not shown) are formed in the target body 202 as described below. The front target section 204 closes off the front side of the target cavity, and includes a target window 218 for receiving a particle beam 114 (FIG. 1) as described above. The front target section 204 abuts a medial target section 206 that surrounds the target body 202. The back side of the target 200 receives an input flow of coolant from a coolant input line 276 in a manner described below. In some implementations, an input plenum (or manifold, chamber, conduit, etc.) 208 of any suitable design is interposed between the coolant input line 276 and the back side of the target body 202 for receiving the input coolant. The input plenum 208 may be formed by a coolant inlet body or region of the medial target section 206 for distributing coolant to the back side of the target body 202 in a manner described below. In this example, a plurality of parallel grooves 344 (FIG. 3) is formed in the back side of the target body 202. The input plenum 208 may taper in the direction of the back side to direct the input coolant flow to the grooves 344. In the present example, the coolant outlet is implemented as a plurality of radial outflow bores 244 circumferentially distributed about the target body 202. The radial outflow bores 244 may terminate at a lateral outer wall 210 of the target body 202. The radial outflow bores 244 may fluidly communicate with one or more coolant output lines 178 (FIG. 1) to enable removal of heat from the target 200 and the target material residing in the target 200, as noted above. To facilitate routing the coolant from the radial outflow bores 244 to the coolant output line(s) 178, an output plenum of any suitable design may be provided. For this purpose, in the illustrated example the output plenum includes one or more chambers 211 and radially distributed axial bores 213 formed in the medial target section 206. Referring to FIG. 3, the input plenum 208 has an entrance 341 that may have any suitable shape and size. In this example, the input plenum 208 is shaped so as to transition to an elongated slot or slit 342 that serves as the entrance to the grooves 344 formed in the back side of the target body 202. FIG. 3A illustrates the elongated slot 342 in front of the grooves 344. A portion of these grooves 344 are visible through the elongated slot 342. The elongated slot 342 is oriented along a vertical direction in FIG. 3A. It will be understood, however, that the term “vertical” is relative to the perspective of FIG. 3A and that in practice no limitations are placed on the orientation of the target 200 or any of its components relative to any particular frame of reference. In the present example, the grooves 344 are oriented transversely relative to the elongated slot 342. Thus, in the example specifically illustrated in FIG. 3A, the grooves 344 may be characterized as being horizontal although again it will be understood that the term “horizontal” is utilized in a relative sense without any limitation being placed on a particular orientation for the grooves 344. The elongated slot 342 is dimensioned such that coolant flowing through the elongated slot 342 will be divided into each of the grooves 344. That is, all grooves 344 are exposed through the elongated slot 342 as shown in FIGS. 3 and 3A. Thus, for example, if fourteen grooves 344 are provided, the input flow of coolant passing through the elongated slot 342 will be divided into fourteen separate, individual input flow paths, with each input flow path being associated with a respective groove 344. In some embodiments, the elongated slot 342 is positioned at a point over each groove 344 equidistant to the first groove end and to the second groove end of the groove 344, and the coolant flow in the liquid coolant flow path for the respective groove 344 is divided approximately equally into the first liquid coolant flow path and the second liquid coolant flow path. FIG. 4 is a perspective view of the front side of the target 200 (or at least the main target section 202) according to the presently described example. For reference purposes, FIG. 4 provides three mutually orthogonal axes that intersect at a point within the target 200 such as in a target cavity 420 thereof: a lateral axis A passing through the target cavity 420 from the front side to the back side, a longitudinal axis B passing through the target cavity 420 from the bottom to the top (from the perspective of FIG. 4), and a transverse axis C also passing through the target cavity 420. Also for reference purposes, the lateral axis A may be associated with a depth of the target 200, the longitudinal axis B may be associated with a length or height of the target 200, and the transverse axis C may be associated with a width of the target 200. This system of three reference axes A, B and C will be utilized in conjunction with FIGS. 5-10 as well. As illustrated in FIG. 4, the target cavity 420 includes a lateral inner wall 422 that defines the cross-section of the target cavity 420 in the plane of the longitudinal axis B and the transverse axis C. The cross-section of the target cavity 420 may include an oblong section that adjoins a rounded top end and a rounded bottom end. That is, the target cavity 420 is elongated in the longitudinal direction. In the present example, the target cavity 420 may open at the front face of the target 200 and may be bounded by the front target section 204 (FIG. 2) after assembly. A channel 424 surrounding the target cavity may be formed in the front face for receiving a suitable gasket or other sealing component (not shown), thereby forming a fluid seal at the interface between the main target section 202 and the front target section 204. FIG. 4 also shows the circumferential series of radial outflow bores 244 that open at the outer surface of the main target section 202. In the present context, term “radial” is relative to the intersection point of the three reference axes A, B and C and is not intended to limit the target 200 as having a circular shape or any other particular shape. FIG. 4 also shows a target inlet (or outlet) bore 432. The target inlet bore 432 may open at a flat section to facilitate fluid connection with a fitting or other component. FIG. 5 is a perspective view of the back side of the target 200 (or at least the main target section 202) according to the present example. The plurality of transversely oriented grooves 344 is formed in the back face. The grooves 344 are adjacent to the target cavity 420 (FIG. 4). The respective widths of the grooves 344 are sized so as to be somewhat greater than the width of the cross-section of the target cavity 420 at all elevations of the target cavity 420. Accordingly, the grooves 344 may collectively exhibit the rounded and oblong shape of the target cavity 420 that characterizes the present example. As described in more detail below, the widths of the grooves 344 enable coolant to be routed in close proximity with the target cavity 420 in the lateral direction to maximize heat transfer from the target cavity 420. FIG. 6 is an elevation view of the back side of the target 200. Each groove 344 is separated from an adjacent groove 344 by a thin, transverse groove wall 646. Each groove 344 runs in the transverse direction between a first groove end 652 and an opposing second groove end 654. Each groove end 652 and 654 fluidly communicates with at least one peripheral bore 656 and 658. Some of the grooves 344 may communicate with more than one peripheral bore 656 and 658. Thus, the number of grooves 344 may be equal to half the number of peripheral bores 656 and 658, or less than half the number of peripheral bores 656 and 658. In the illustrated example, the upper two grooves 344 and the bottom two grooves 344 each communicate with two peripheral bores 656 and 658 at their respective ends 652 and 654 for ease of fabrication and to facilitate the close spacing between adjacent peripheral bores 656 or 658. As described in more detail below, the peripheral bores 656 and 658 circumscribe the cross-section of the target cavity 420 (FIG. 4) in close proximity therewith and run in the lateral direction toward the front side of the target 200. From FIGS. 3 and 6, it can be seen that each individual groove 344 splits the coolant input flow from the elongated slot 342 (FIG. 3) into two flows that run in opposite transverse directions to respective peripheral bores 656 and 658 located at the first groove end 652 and second groove end 654. Assuming the width of the elongated slot 342 is uniform as illustrated in FIG. 3 and the elongated slot 342 is positioned centrally between the first groove ends 652 and the second groove ends 654, each groove 344 may split the coolant input flow generally evenly into the two transverse directions. In alternative implementations, the width and/or the position of the elongated slot 342 may vary along the longitudinal axis B to consequently vary the flow of coolant into various grooves 344 and corresponding peripheral bores 656 and 658. The coolant flow rate into at least one of the plurality of parallel grooves 344 can thereby be made different from the coolant flow rate into at least one other groove 344. In the illustrated example in which fourteen grooves 344 are provided, the fourteen coolant flow paths entering the grooves 344 are thus divided into twenty-eight transverse coolant flow paths. In the illustrated example in which some of the groove ends 652 and 654 include more than one peripheral bore 656 or 658, additional flow splitting occurs. Specifically, the present example includes twenty-eight groove ends 652 and 654 but thirty-six peripheral bores 656 and 658. Thus, some of the twenty-eight flow paths running transversely to the twenty-eight groove ends 652 and 654 are further divided. As a result, a total of thirty-six coolant flow paths are provided in the corresponding peripheral bores 656 and 658 in the present example. The thirty-six coolant flow paths run through the peripheral bores 656 and 658 in the lateral direction in close proximity to each other and to the target cavity 420, thereby enabling a highly efficient means for removing heat from the target material in the target cavity 420. In other implementations, the number of coolant flow paths running in the various directions described herein may be different, the presently illustrated implementation being but one example. In some examples, the thickness of each groove wall 646 (in the longitudinal direction) ranges from 0.002 to 0.125 inch. The cross-sectional area of each groove 344 may be defined by the width of the groove 344 in the transverse direction and the height of the groove 344 in the longitudinal direction (between adjacent groove walls 646). In some examples, the height of each groove 344 ranges from 0.01 to 0.125 inch. In some examples, the diameter of each peripheral bore 656 and 658 ranges from 0.01 to 0.25 inch. In the example illustrated in the FIG. 6, the peripheral bores 656 and 658 may generally be divided into a first set associated with the first groove ends 652 and a second set associated with the second groove ends 654. In each first or second set, the peripheral bores 656 and 658 are closely spaced with each other to maximize the amount of “coverage” of the target cavity 420 and thus the amount of surface area of the peripheral bores 656 and 658 available for transferring heat from the target cavity 420. In some examples, the gap or spacing 648 between any pair of adjacent peripheral bores 656 or 658 of the first or second set ranges from 0.002 to 0.125 inch. The minimal amount of target structure between adjacent peripheral bores 656 or 658 result in the dense coverage of the target cavity discussed above. It will be noted that in FIG. 6 the uppermost peripheral bore 656 of the first set is spaced at a greater distance from the uppermost peripheral bore 658 of the second set (across the longitudinal axis B) in comparison to the spacing 648 between adjacent peripheral bores 656 or 658 of the first or second set. The same may be said for the respective lowermost peripheral bores 656 or 658 of the first and second sets. This additional spacing is done in the present implementation merely to accommodate the location of the target material inlet bore and outlet bore, which by example are respectively positioned at the top and bottom of the target cavity 420 as shown in FIGS. 3-5 and 10. It will be understood, however, that in other implementations the target material inlet bore and outlet bore may be located in other positions whereby additional spacing between any two adjacent peripheral bores 656 or 658 occurs at a different location or not at all. Apart from the foregoing, the division of the peripheral bores 656 and 658 into first and second sets is conceptual and done for illustrative purposes. FIG. 7 is a perspective, cross-sectional view of the target that has been cut-away at a plane of the lateral axis A and longitudinal axis B that reveals two of the peripheral bores 656 fluidly interconnecting respective grooves 344 and radial outflow bores 244. The target cavity 420 is bounded by the lateral inner wall 422 and an adjoining back inner wall 726. The lateral inner wall 422 is adjacent to the circumferentially surrounding peripheral bores 656 and separated from the peripheral bores 656 by a relatively small distance through an annular portion 728 of the target structure. In some examples, the annular portion 728 has a thickness (in any radial direction relative to the lateral axis A) ranging from 0.002 to 0.5 inch. In other non-limiting examples, the thickness of the annular portion 728 ranges from 0.005 to 0.15 inch. In the illustrated example, the peripheral bores 656 run parallel to the lateral inner wall 422 such that the thickness of the annular portion 728 is uniform along the lateral direction. In alternative implementations, however, the peripheral bores 656 and/or the lateral inner wall 422 may be oriented such that this parallelism is not maintained. In the illustrated example, the series of peripheral bores 656 largely spans the entire extent of the area of the lateral inner wall 422 coaxially about the lateral axis A (see also FIG. 6). Consequently, the peripheral bores 656 collectively provide a large surface area for transferring heat from the lateral inner surface 422, through the annular portion 728, and to the coolant flowing through the peripheral bores 656. Each peripheral bore 656 is bounded by an inner peripheral bore wall 758 that extends from the corresponding groove 344 to the corresponding radial outflow bore 244. Each inner peripheral bore wall 758 has a surface area, and the total surface area of the plurality of peripheral bores 656 may be defined as the summation of the surface areas of the individual inner peripheral bore walls 758. As also shown in FIG. 7, the back inner wall 726 of the target cavity 420 is adjacent to the grooves 344 and separated from the grooves 344 by a relatively small distance through a back (or longitudinal) portion 730 of the target structure. In some examples, the back portion 730 has a thickness (in the lateral direction, over at least a majority of the grooves 344) ranging from 0.002 to 0.5 inch. In the illustrated example, the series of parallel grooves 344 spans beyond the extent of the area of the back inner wall 726 to facilitate maximizing coverage of the target cavity 420 by the peripheral bores 656, although in other examples may span at least a majority of the area of the back inner wall 726. Moreover, the transverse groove walls or septa 646 (FIG. 6) are thin. Consequently, the grooves 344 collectively provide a large surface area for transferring heat from the back inner wall 726, through the back portion 730, and to the coolant flowing through the grooves 344. The total cross-sectional area of the plurality of grooves 344 may be defined as the summation of the cross-sectional areas of the individual grooves 344. As noted above, each groove 344 generally defines two coolant flow paths running along the transverse direction, with one coolant flow path running to the peripheral bore(s) 656 located at one groove end 652 (FIG. 6) and the other coolant flow path running the opposing peripheral bore(s) 658 located at the other groove end 654 of the same groove 344. Each coolant flow path then takes an orthogonal turn into a corresponding peripheral bore 656 or 658 and runs in the lateral direction, again in close proximity to the target cavity 420. Thus, the coolant continues to remove heat from the target cavity 420 as it flows toward the front side of the target 200 along the lateral flow paths. To maximize heat removal, the peripheral bores 656 and 658 may extend over a large majority of the depth of the target cavity 420. Each peripheral bore 656 and 658 runs to at least one radial outflow bore 244. The radial outflow bores 244 may be sized (e.g., cross-sectional flow area) larger than the peripheral bores 656 and 658 and positioned such that more than one peripheral bore 656 and 658 terminates at the same radial outflow bore 244. Thus, the number of radial outflow bores 244 may be equal to or less than the number of peripheral bores 656 and 658. This configuration also minimizes the pressure drop in the radial outflow bores 244. The cross-sectional flow area of each radial outflow bore 244 may progressively increase along the radial direction from the end of the peripheral bore 656 or 658 to the outer lateral wall 210 of the target structure, as illustrated in FIG. 7. Once the coolant reaches a radial outflow bore 244, the coolant then takes an orthogonal turn into the radial outflow bore 244. The coolant then runs in a radial outward direction to the end of the radial outflow bore 244 at the lateral outer surface 210 of the target 200. While flowing in the radial outflow bore 244, the coolant continues to pick up heat energy. In the illustrated example, the radial outflow bores 244 are located in close proximity to the front side of the target 200 that receives the particle beam 114 (FIG. 1), in closer proximity to the front side than to the back side. In some non-limiting examples, the radial outflow bores 244 are located at a distance from the front side along the lateral axis A ranging from 0.01 to 0.5 inch. Moreover, the radial outflow bores 244 are dimensioned so as to provide a large surface area available for heat transfer from the structural (solid) body constituting the target 200. By this configuration, the coolant flowing through the radial outflow bores 244 is able to remove heat from the structural target body as well as from the target material being irradiated in the target cavity 420. Upon reaching the lateral outer surface of the target 200, the coolant may then be flowed away from the target 200 and recirculated back to the grooves 344 in the manner described above. It thus can be seen that both the grooves 344 on the back side of the target 200 and the peripheral bores 656 and 658 running through the depth of the target 200 cover the inside surfaces of the target cavity 420 very densely and with a minimum of wall thickness between the coolant and the target cavity 420. The radial outflow bores 244 provide additional heat-removing capacity in the manner described above. Moreover, the transverse grooves 344, peripheral bores 656 and 658 and radial outflow bores 244 are dimensioned and positioned in a configuration that maintains a high-velocity coolant flow through the target 200 from input to output, thereby enabling the coolant to rapidly carry away the heat being deposited by the particle beam 114 (FIG. 1). This foregoing configuration therefore maximizes heat removal from the target cavity 420. FIG. 8 is a cross-sectional elevation view of the target 200 that has been cut-away at a plane of the longitudinal axis B and transverse axis C that reveals the radial outflow bores 244. For reference purposes, the center of the target 200 is taken to be the geometrical center of the target cavity 420, and the origin of the intersecting lateral axis A, longitudinal axis B and transverse axis C has been located at this center. Utilizing this frame of reference, each radial outflow bore 244 is located along a radius projected from the center. As noted above, one or more of the radial outflow bores 244 may fluidly communicate with more than one peripheral bore 656 or 648 (FIG. 7). In the illustrated example, each radial outflow bore 244 communicates with two peripheral bores 656 or 658. Thus, the thirty-six lateral coolant flow paths running through the respective peripheral bores 656 and 658 are reduced to eighteen radial coolant flow paths in the eighteen radial outflow bores 244 illustrated in FIG. 8. FIG. 9 is a cross-sectional elevation view of the target 200 that has been cut-away at a plane of the lateral axis A and transverse axis C that reveals one of the grooves 344 in fluid communication with a corresponding pair of peripheral bores 656 and 658 and radial outflow bores 244. Once an input flow of coolant to the back side of the target 200 is established, the resulting coolant flow paths may be summarized as follows. Initially, the coolant is flowed to the grooves 344 generally along the lateral direction, as indicated by an arrow 902. The coolant input flow 902 encounters the grooves 344 in close proximity with back inner wall 726 of the target cavity 420, and thus the coolant is able to immediately begin removing heat from the target cavity 420. When the input flow 902 encounters the grooves 344, the input flow 902 is initially divided along the longitudinal direction into each groove 344. Thus, each groove 344 is associated with a coolant input flow path 902 separate from the other grooves 344. The grooves 344 are orthogonal to the initial input flow 902. Thus, in each groove 344 the input flow 902 is further divided such that one part of the input flow 902 is diverted to one groove end 652 while the other part of the input flow 902 is diverted to the opposing groove end 654 of the same groove 344. The resulting two transverse coolant flow paths in the groove 344 are indicated by arrows 904 and 906. When each transverse coolant flow 904 and 906 reaches a groove end 652 or 654, that transverse coolant flow 904 and 906 is then diverted orthogonally into the peripheral bore 656 or 658 located at that groove end 652 or 654 (or one of the peripheral bores 656 or 658 in the case where more than one peripheral bore 656 or 658 is formed at a single groove end 652 or 654). The resulting lateral coolant flow paths are indicated by arrows 912 and 914. The lateral coolant flows 912 and 914 then run through the respective peripheral bores 656 and 658 to the corresponding radial outflow bores 244. As coolant is fed into the radial outflow bores 244, it is diverted into corresponding radial coolant outflow paths as indicated by arrows 916. The coolant in each radial outflow bore 244 reaches the outer lateral wall 210 of the target 200 and is conducted away to an external heat exchanging device as described previously in this disclosure. FIG. 9 may be considered as showing the top end of the target cavity 420 at which the target material inlet bore 432 is located by example (or where the outlet bore may be located in another example). Alternatively, FIG. 9 may be considered as showing the bottom end of the target cavity 420 at which the target material outlet bore (or inlet bore 432) is located. The following description will refer to the target material inlet bore 432, as located at the top end in the present example, with the understanding that the discussion may also apply to the target material outlet bore and/or to the bottom end of the target cavity 420. In the illustrated implementation, the inlet bore 432 is surrounded by an inlet pocket or depression 982 formed in the lateral inner wall 422 of the target cavity 420. The inlet pocket 982 may have any size and shape suitable for complete filling of the target cavity 420. The length of the inlet pocket 982 in the lateral direction may be elongated relative to the width of the inlet pocket 982 in the transverse direction. In the present example, the inlet pocket 982 is elongated in the lateral direction and the width of the inlet pocket 982 in the transverse direction gradually tapers down (decreases) in the lateral direction toward the front side of the target 200. The target material inlet bore 432 is located in the region of the inlet pocket 982 having the maximum width. The resulting “teardrop” shape of the inlet pocket 982, with the target material inlet bore 432 located in the bulk of the teardrop, has been found to be effective for complete filling of the target cavity 420. Likewise, an outlet pocket (not shown) may surround the outlet bore, and may have any size and shape suitable for complete recovery of target material. In the present example, the outlet pocket may be sized and shaped similarly to the illustrated inlet pocket 982. FIG. 10 is a cross-sectional elevation view of the target 200 that has been cut-away at a plane of the lateral axis A and longitudinal axis B that reveals the target material inlet bore 432 and an outlet bore 1034. In this example, the inlet bore 432 fluidly communicates with an inlet pocket 982 as described above, and the outlet bore 1034 fluidly communicates with an outlet pocket 1084. As noted above, the respective sizes and shapes of the inlet pocket 982 and the outlet pocket 1084 may be the same or different. In the illustrated example, the above-noted tapering of each pocket 982 and 1084 also occurs along the longitudinal axis A, with each pocket 982 and 1084 being deepest in the vicinity of the inlet bore 432 or outlet bore 1034. FIG. 11 is a perspective view of an example of a target assembly 1100 in which the target 200 may be included, and FIG. 12 is a cross-sectional view of the target assembly 1100. The target assembly 1100 may be utilized in a radionuclide production system such as illustrated by example in FIG. 1, or in other, differently configured radionuclide production systems. The target assembly 1100 generally includes the front target section 204 and the medial target section 206 as described above. In addition, the target assembly 1100 in this example includes a back target section 1121. The back target section 1121 may include a chamber 1123 (FIG. 12) that serves as part of the output plenum for carrying away heated output coolant from the target body 202. The back target section 1121 may also include bores communicating with respective coolant input fittings 1125 and coolant output fittings 1127. In the present example, the coolant input fittings 1125 communicate with the input plenum 208 and the coolant output fittings 1127 communicate with the chamber 1123 of the output plenum. The target assembly 1100 may also include a beam guide 1130 for directing a particle beam from a particle beam source (e.g., the particle beam source 140 shown in FIG. 1) to the target window 218 (FIG. 12). As also shown in FIG. 12, various adjacent components of the target assembly 1100 may be fluidly sealed by sealing elements (e.g., o-rings, gaskets, etc.) seated in grooves or channels formed in or on such components. In particular, the arrangement of the target window 218 interposed between the target body 202 and the front target section 204 may be fluidly sealed by a sealing element seated in a channel 1241 formed in the front side of the target body 202, and/or by a sealing element seated in a channel 1243 formed in the front target section 204. Generally, the target window 218 may have any shape and planar size, so long as the outer diameter (or other relevant dimension, more generally perimeter) of the target window 218 is large enough that the target window 218 covers the opening of the target cavity 420. In practice, the outer perimeter of the target window 218 is large enough to accommodate the use of fluid sealing means such as the illustrated sealing element/channel 1241 and/or 1243. FIG. 12 illustrates one non-limiting example in which the area of the target window 218 is coextensive with that of the front side of the target body 202. Continuing with FIG. 12, the location of the peripheral bores 656 in relation to the target cavity 420, as well as to other components of the target 200 and associated target assembly 1100, optimizes the ability of the coolant circulating through the target 200 to remove heat from the target 200. The peripheral bores 656 closely surround the target cavity 420 and span most of the axial depth of the target cavity 420 to maximize the amount of heat transfer therefrom. Relative to the lateral axis running through the target cavity 420, the peripheral bores 656 are arranged about a perimeter at a radial distance not much greater than the radial extent of the target cavity 420. This arrangement of the peripheral bores 656 may be characterized in relation to the target window 218 and the associated sealing element/channel 1241 and/or 1243. It can be seen that the perimeter of the peripheral bores 656 is less that the outer perimeter of the target window 218. Stated in another way, the area taken up by the arrangement of peripheral bores 656 is within the area of the target window 218. Additionally or alternatively, the perimeter of the peripheral bores 656 is less that the perimeter of the sealing element/channels 1241 and 1243. This arrangement of the peripheral bores 656 is facilitated by the provision of the radial outflow bores 244, which allow the peripheral bores 656 to run close to the target cavity 420 and close up to the target window 218. Additionally, the radial outflow bores 244 maximize heat removal from the target window 218 and the region of the target body 202 proximal to the target window 218 The advantages provided by the present teachings may be further illustrated by comparing FIGS. 13 and 14. FIG. 13 is an exploded perspective view of the target 200, a sealing element 1351, and the target window 218. The peripheral bores 656 (FIG. 12) may be placed within the perimeter of the channel 1241 in which the sealing element 1351 is seated, as well as within the perimeter of the target window 218. Coolant from the peripheral bores 656 is carried away by the radial outflow bores 244, enabling the peripheral bores 656 to be immediately adjacent to the target cavity 240. FIG. 13 also shows an alternative circular cross-section for the target cavity 240. By contrast, FIG. 14 is an exploded perspective view of a conventional design of a target 1400 and its associated sealing element 1451 and target window 1418. In FIG. 14, the sealing element 1451 is seated in a recess 1441 formed in the target body and the target window 1418 is mounted in another recess 1445 concentrically surrounding the sealing element recess 1441. This conventional target 1400 has a radial distribution of axial bores 1456 for conducting coolant from the back side to the front side of the target 1400. These axial bores 1456, however, must be arranged far away from the target cavity 1440 to avoid the target window 1418 and the sealing element 1451. Hence, the axial bores 1456 are located outside the perimeter of both the sealing element recess 1441 and the target window 1418. In general, terms such as “communicate” and “in . . . communication with” (for example, a first component “communicates with” or “is in communication with” a second component) are used herein to indicate a structural, functional, mechanical, electrical, signal, optical, magnetic, electromagnetic, ionic or fluidic relationship between two or more components or elements. As such, the fact that one component is said to communicate with a second component is not intended to exclude the possibility that additional components may be present between, and/or operatively associated or engaged with, the first and second components. It will be understood that various aspects or details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation—the invention being defined by the claims.
047298707	abstract	The nuclear fuel element according to the invention comprises a can, which is sealed at its ends by plugs, whereof a cylindrical portion is force fitted into the can. The internal diameter of the can can vary between a maximum diameter and a minimum diameter, the diameter of the cylindrical portion being equal to said minimum diameter. Three serrations machined on the cylindrical portion form beads, whose thickness is equal to half the difference between the maximum diameter and the minimum diameter of the can.
	summary
	summary
	claims	1. A method of preparing spent nuclear fuel for dry storage comprising:a) flowing a non-reactive gas through a cavity;b) repetitively measuring dew point temperature of the non-reactive gas exiting the cavity; andc) upon the dew point temperature of the non-reactive gas exiting, the cavity being measured to be at or below a predetermined dew point temperature for a predetermined time, discontinuing the flow of the non-reactive gas and sealing the cavity. 2. The method of claim 1 wherein step (a) comprises flowing the non-reactive gas through the cavity at a predetermined flow rate. 3. The method of claim 2 wherein the cavity has a volume and the predetermined flow rate is chosen so that the volume of the cavity is turned over 25 to 50 times per hour. 4. The method of claim 1 wherein the predetermined dew point temperature is selected to correspond to a desired vapor pressure within the cavity. 5. The method of claim 1 wherein the predetermined dew point temperature is in a range of approximately 20 to 26° F., and the predetermined time is in a range of approximately 25 to 35 minutes. 6. The method of claim 5 wherein the predetermined dew point temperature is approximately 22.9° F. and the predetermined time is approximately 30 minutes. 7. The method of claim 1 further comprising:d) drying the on-reactive gas that exits the cavity after the dew point temperature is measured; ande) re-circulating the dried non-reactive gas through the cavity. 8. The method of claim 7 wherein step d) comprises drying the non-reactive gas with a desiccant. 9. The method of claim 7 wherein step d) comprises drying the non-reactive gas by chilling the non-reactive gas. 10. The method of claim 1 wherein the non-reactive gas is nitrogen, carbon dioxide, light hydrocarbon gases, or a noble gas selected from the group consisting of helium, argon, neon, radon, krypton, and xenon. 11. The method of claim 1 wherein the predetermined dew-point temperature is selected to correspond to a vapor pressure of 3 Torr or less in the cavity. 12. The method of claim 1 further comprising:d) drying the non-reactive gas that exits the cavity after the dew point temperature is measured;e) re-circulating the dried non-reactive gas through the cavity;wherein the predetermined dew-point temperature is selected to correspond to a vapor pressure of 3 Torr or less in the cavity;wherein step (a) comprises flowing the non-reactive gas through the cavity at a predetermined flow rate that results in a volume of the cavity being turned over 25 to 50 times per hour;wherein the non-reactive gas is helium;wherein the cavity is formed by a canister and is loaded, with spent nuclear fuel, the canister positioned in a cask. 13. A system for drying a cavity loaded with spent nuclear fuel comprising a canister forming the cavity, the cavity havingan inlet and an outlet;a source of non-reactive gas;means for flowing the non-reactive gas from the source of non-reactive gas through the cavity; andmeans for repetitively measuring the dew point temperature of the non-reactive gas exiting the cavity. 14. The system of claim 13 further comprising means for drying the non reactive gas, the drying means located downstream of the of the dew point temperature measuring means. 15. The system of claim 14 wherein the drying means comprises a chiller. 16. The system of claim 14 wherein the drying means comprises a desiccant. 17. The system of claim 14 further comprising means for re-circulating the non-reactive gas from the drying means back into the non-reactive gas source. 18. The system of claim 13 further comprising:a controller operably coupled to the dew point temperature measuring, means;wherein the dew point temperature measuring means is adapted to create signals indicative of the measured dew point temperature of the non-reactive gas and transmit the signals to the controller; andwherein the controller is adapted to analyze the signals and upon determining that the signals indicate that the measured dew point temperature is at or below a predetermined dew point temperature for a predetermined time the controller is further adapted to (1) cease flow of the non-reactive gas through the cavity; and/or (2) activate a means for indicating that the cavity is dry. 19. The system of claim 13 further comprising a cask, the canister positioned within the cask. 20. The system of claim 13 further comprising:a cask, the canister positioned within the cask;means for drying the non-reactive gas, the drying means located downstream of the dew point temperature measuring means;means for re-circulating the non-reactive gas from the drying means back into the non-reactive gas source, thereby forming a closed-loop system;a controller operably coupled to the dew point temperature measuring means;wherein the dew point temperature measuring means is adapted to create signals indicative of the measured dew point temperature of the non-reactive gas and transmit the signals to the controller; andwherein the controller is adapted to analyze the signals and upon determining that the signals correspond to the measured dew point temperature being at or below a predetermined dew point temperature for a predetermined time, the controller is further adapted to (1) cease flow of the non-reactive gas through the cavity; and/or (2) activate a means for indicating that the cavity is dry;wherein the predetermined dew point temperature is in a range of approximately 20 to 26° F., the predetermined time is in a range of approximately 25 to 35 minutes, and the flowing means circulates the non-reactive gas through the cavity at a predetermined flow rate that results in a volume of the cavity being turned over 25 to 50 times per wherein the dew point temperature measuring means comprises a hygrometer.
	claims	1. A method of fabricating a probe including a cantilever, a body supporting said cantilever and a tip formed at an end of the cantilever, comprising the steps of:(a) providing a silicon substrate having <110> directional crystal structure as a starting wafer, wherein the substrate has an upper surface and a lower surface;(b) forming a first mask layer on the upper and lower surfaces of the silicon substrate;(c) coating a first photoresist on the first mask layer on the upper surface of the silicon substrate and patterning th photoresist to leave portions of the first photoresist defining the tip and the body;(d) etching the silicon substrate using the remaining first photoresist as a mask to remove portions of the first mask layer;(e) removing the remaining first photoresist;(f) etching the silicon substrate in a predetermined depth using the first mask layer remaining on the upper surface of the silicon substrate as a mask to form the tip;(g) removing the remaining first mask layer;(h) forming a second mask layer on an area of the silicon substrate except for an area to be formed with the body and the cantilever;(i) forming a boron-diffused layer by diffusing boron into the silicon substrate using the second mask layer as a mask so that the boron is diffused only into a portion of he silicon substrate to be formed with the cantilever and the body;(j) removing the second mask layer;(k) forming a third mask layer on the upper and lower surfaces of the silicon substrate;(l) coating a second photoresist on the third layer on the upper surface of the silicon substrate and patterning the photoresist to cover only portions of the second photoresist to be formed with the cantilever and the body;(m) etching the silicon substrate using the remaining second photoresist as a mask to remove portions of the third mask layer;(n) removing the remaining second photoresist and third mask layer on the lower surface of the substrate; and(o) performing an anisotropic etching of the silicon substrate using the third mask layer remaining on the upper surface of the silicon substrate as a mask so that the silicon substrate is etched in a vertical direction from the upper and lower surfaces of the substrate thereby forming the body and the cantilever. 2. The method of fabricating a probe according to claim 1, wherein the first, second and third mask layers are a silicon dioxide. 3. The method of fabricating a probe according to claim 1, wherein step (f) of etching the silicon substrate to form the tip is performed by a reactive ion etching process using SbF6, He and O2 gases. 4. The method of fabricating a probe according to claim 1, wherein step (i) of forming the boron-diffused layer comprises steps of ion-implanting the boron and diffusing the boron by a heat treatment. 5. The method of fabricating a probe according to claim 1, wherein step (i) of forming the boron-diffused layer comprises a step of diffusing the boron by a heat treatment using a solid source containing the boron. 6. The method of fabricating a probe according to claim 1, wherein the boron-diffused layer serves as an etching-stopper layer during the anisotropic etching. 7. The method of fabricating a probe according to claim 1, wherein the anisotropic etching of the silicon substrate is performed by using an etchant selected from the group consisting of ethylene diamine pyrocathecol, tetramethyl ammonium hydroxide and potassium hydroxide. 8. The method of fabricating a probe according to claim 3, wherein a sharpness of the tip is adjusted by varying a process condition of a constitution ratio of the gases, a power, or a pressure during the reactive ion etching process. 9. The method of fabricating a probe according to claim 4, wherein a thickness of the boron-diffused layer is determined by a temperature during the heat treatment and a time of diffusing the boron. 10. The method of fabricating a probe according to claim 5, wherein a thickness of the boron-diffused layer is determined by a temperature during the heat treatment and a time of diffusing the boron.
	claims	1. A charged particle beam system comprising:an ion source generating a plurality of different kinds of ions differing in weight from each other;an accelerator accelerating the ions generated in the ion source and that includes a plurality of magnets;a beam transport system transporting an ion beam extracted from the accelerator; andan irradiation nozzle irradiating the ion beam to an irradiation target;a rotating gantry that rotates the irradiation nozzle around the irradiation target; anda control apparatus configured to control the rotating gantry, the irradiation nozzle, and the accelerator to select which of the different kinds of ions are irradiated from the irradiation nozzle from a plurality of different irradiation directions based on a water equivalent depth of the irradiation target at each of the irradiation directions, andwherein the control apparatus is configured to control respective magnetic field strengths of the magnets when accelerating the different kinds of ions at a radius along a circular track, and the accelerator accelerates a first kind of the ions to a first maximum energy and accelerates a second kind of the ions to a second maximum energy, andwherein the control apparatus is further configured to set, the first maximum energy and the second maximum energy such that a first magnetic rigidity of the accelerator for accelerating the first kind of ions to the first maximum energy and a second magnetic rigidity of the accelerator for accelerating the second kind of ions to the second maximum energy are approximately equal. 2. The charged particle beam system according to claim 1,wherein the irradiation nozzle is installed in the rotating gantry,wherein the control apparatus is configured to control the accelerator to accelerate the plurality of different kinds of ions so that an underwater range at a highest energy after acceleration is different in each species of the ions, andwherein the water equivalent depth of the irradiation target in a first one of the irradiation directions is equal to or less than the underwater range at the highest energy after the acceleration of the first kind of ions, andwherein the selected ions are transported to the irradiation nozzle using the ion source, the accelerator, the beam transport system, and the rotating gantry, thereby irradiating the irradiation target with the selected ions from the irradiation nozzle. 3. The charged particle beam system according to claim 2,wherein the control apparatus is configured to compare the water equivalent depth of each of a plurality of layers of the irradiation target divided in a depth direction in the irradiation target with a longest underwater range of each of the different kinds of ions, andwherein the control apparatus is configured to, for each of the layers and for each of the different irradiation directions, select the first kind of ions to be irradiated when the water equivalent depth of the respective layer is greater than 4 cm from a surface in the respective irradiation direction and select the second kind of ions to be irradiated when the water equivalent depth of the respective layer is equal to or less than 4 cm from the surface in the respective irradiation direction. 4. The charged particle beam system according to claim 2,wherein the irradiation nozzle includes a scanning magnet,wherein the control apparatus is configured to control an irradiation position and irradiation range of the ions from the irradiation nozzle in a lateral direction by controlling the scanning magnet based on a position and a range in the lateral direction of each of a plurality of volume elements of the irradiation target, andwherein the control apparatus is configured to, for each of the volume elements and for each of the different irradiation directions, select the first kind of ions to be irradiated when the water equivalent depth of the respective volume element is greater than 4 cm from a surface in the respective irradiation direction and select the second kind of ions to be irradiated when the water equivalent depth of the respective volume element is equal to or less than 4 cm from the surface in the respective irradiation direction. 5. The charged particle beam system according to claim 1,wherein the irradiation nozzle is installed in the rotating gantry,wherein the control apparatus is configured to control the accelerator to accelerate the plurality of different kinds of ions so that an underwater range after acceleration of a heaviest kind of the ions to a highest energy is shorter than an underwater range after acceleration of ions other than the heaviest kind of the ions to a highest energy. 6. The charged particle beam system according to claim 1,wherein the irradiation nozzle is installed in the rotating gantry,wherein the control apparatus is configured to control the accelerator to accelerate the plurality of different kinds of ions so that an underwater range of a heaviest kind of the ions after acceleration to a highest energy is shorter than an underwater range after acceleration of ions lighter than said heaviest kind of the ions after acceleration to a highest energy. 7. The charged particle beam system according to claim 1,wherein the irradiation nozzle is installed in the rotating gantry,wherein the control apparatus is configured to control the accelerator to accelerate each of the plurality of different kinds of ions so that an underwater range after accelerating the different kinds of ions to a highest energy decreases in correspondence with an increase in ion weight thereof,wherein the selected ions are transported to the irradiation nozzle using the ion source, accelerator, beam transport system, and rotating gantry, thereby irradiating the irradiation target with the selected ions from the irradiation nozzle. 8. The charged particle beam system according to claim 1,wherein the first kind of ions are selected and irradiated from a first one of the irradiation directions when the water equivalent depth of the irradiation target is greater than 4 cm, and the second kind of ions are selected and irradiated from a second one of the irradiation directions when the water equivalent depth of the irradiation target is equal to or less than 4 cm. 9. The charged particle beam system according to claim 8,wherein the first kind of ions are hydrogen ions and the second kind of ions are helium ions. 10. The charged particle beam system according to claim 1,wherein each of the first magnetic rigidity and the second magnetic rigidity is 4.5 Tm. 11. The charged particle beam system according to claim 1,wherein the control apparatus is configured to control the rotating gantry, the irradiation nozzle and the accelerator to select the first kind of ions to be irradiated from a second one of the irradiation directions for the water equivalent depth of the irradiation target that is greater than 4 cm, and thereafter select the second kind of ions to be irradiated from the second one of the irradiation directions for the water equivalent depth of the irradiation target that is equal to or less than 4 cm. 12. The charged particle beam system according to claim 1,wherein the first kind ions are selected and irradiated from a first one of the irradiation directions when the water equivalent depth of the irradiation target is greater than or equal to 10 cm, and the second kind of ions are selected and irradiated from a second one of the irradiation directions when the water equivalent depth of the irradiation target is less than 10 cm. 13. The charged particle beam system according to claim 12,wherein the first kind of ions are helium ions and the second kind of ions are carbon ions. 14. The charged particle beam system according to claim 12,wherein each of the first magnetic rigidity and the second magnetic rigidity is 4.5 Tm. 15. The charged particle beam system according to claim 12,wherein the control apparatus is configured to control the rotating gantry, the irradiation nozzle and the accelerator to select the first kind of ions to be irradiated from the second one of the irradiation directions for the water equivalent depth of the irradiation target that is greater than or equal to 10 cm, and thereafter select the second kind of ions to be irradiated from the second one of the irradiation directions for the water equivalent depth of the irradiation target that is less than 10 cm. 16. The charged particle beam system according to claim 1, wherein the first magnetic rigidity of the accelerator for accelerating the first kind of ions to the first maximum energy of 220 MeV and the second magnetic rigidity of the accelerator for accelerating the second kind of ions to the second maximum energy of 69 MeV are approximately equal. 17. The charged particle beam system according to claim 1, wherein the first magnetic rigidity of the accelerator for accelerating the first kind of ions to the first maximum energy and the second magnetic rigidity of the accelerator for accelerating the second kind of ions to the second maximum energy are approximately ½ of a third magnetic rigidity for obtaining a water equivalent depth of 30 cm for the second kind of ions.
044329318	description	DESCRIPTION OF THE PREFERRED EMBODIMENT For convenience the present invention will be described with respect to its application to a nuclear reactor. It will be appreciated, however, that the system of the present invention also could be utilized in a variety of other types of facilities. it is particularly well suited for a nuclear reactor since there are many parts of the reactor, such as weld seams and the like, which must be inspected periodically and are inaccessible to personnel because of temperature, radiation, or space constraints. Referring to FIG. 1, therein is depicted a nuclear reactor 10, for example, a liquid metal-cooled breeder reactor, which includes among other things a primary vessel 12 for containing a reactor core, coolant, and other components not shown. Primary vessel 12 is surrounded by a containment vessel 14. The outer wall of primary vessel 12 and inner wall of containment vessel 14 define an annular space therebetween. Located within this annular space there is provided at least one and preferably a plurality of substantially rigid fixed conduit members 16. As depicted, each fixed conduit member 16 terminates at one end adjacent an upper portion of the annular space defined between vessels 12 and 14 and at the other end adjacent an area of interest to be inspected, as will be described in greater detail later. When the system includes a plurality of conduit members 16 they are clustered adjacent to one another in one or more groups at the upper end to minimize the amount of movement required to insert a flexible hose member 18 into the various fixed conduit members 16. Advantageously, there also is provided a drive assembly 20 to facilitate the insertion or removal of hose member 18 into fixed conduit member 16. As depicted, hose member 18 is stored on and fed from a spool assembly 22. Through appropriate couplings known to those versed in the art, hose member 18 is provided with a source of a pressurizing fluid 24, electrical power 26 and connection to a television viewing screen (T.V. Inspecting Screen) and recorder 28. Referring now to FIG. 2, it is seen that drive assembly 20 comprises a drive wheel 30 having about its outer periphery a plurality of grasping assemblies 32 which are spaced apart to engage, in this preferred embodiment, roller assemblies 34 which are affixed at intervals along the length of flexible hose member 18. As depicted in FIGS. 3 and 4, grasping assemblies 32 comprise a pair of spaced apart, upwardly extending, U-shaped members 36 adapted to receive hose member 18 while not permitting the passage therethrough of roller assemblies 34. U-shaped members 36 are fixed to the outer periphery of drive wheel 30 by any conventional means such as bonding, welding, or mechanical fasteners such as bolts 38. Alternatively, of course, the U-shaped members could be machined as an integral part of drive wheel 30. Turning again to FIG. 2, drive wheel 30 is connected to a drive motor 40 to facilitate insertion or removal of hose member 18. Drive motor 40 and drive wheel 30 are supported by a support member 42 which is affixed to a base member 44. In accordance with this particular preferred embodiment, base member 44 is provided with wheels 46 for engagement with tracks 48 which are provided about the upper periphery of containment vessel 14 to aid in positioning drive wheel 30 and hose member 18 over the selected fixed conduit member 16. Where space permits it generally is preferred that spool assembly 22 also be affixed to base member 44 to insure appropriate alignment between drive wheel 30 and spool assembly 22. For the safety of personnel operating in the vicinity of drive assembly 20, drive wheel 30 generally is enshrouded as much as possible with a housing or cover 50. In addition cover 50 also ensures that roller assemblies 34 cannot lift off of grasping assemblies 32. Referring now to FIG. 5, there is shown a typical segment of a fixed conduit member 16 having disposed therein a flexible hose member 18 terminating in a television camera assembly 52. Fixed conduit member 16 is provided with a plurality of closely spaced apertures or slots 54 at selected points to permit observation of either the exterior of primary vessel 12 or the interior of containment vessel 14 at points of interest. Circulation of pressurizing fluid and coolant fluid to camera 52 as well as for electrical power and receiving signals from camera 52 are provided by conduit members 56 which are located within and coaxial with flexible hose member 18. Typically the hose member will be a length of metal bellows encased in a metal mesh which is commercially available from a variety of sources. FIG. 6 shows an enlarged exploded view of camera assembly 34 wherein the details of construction are more clearly seen. For illustrative purposes; fixed conduit member 16 is shown attached to the inner wall of the primary vessel 12 by a bracket 58 such that fixed conduit member 16 is located above and extends along the length of the weld seam 60 to be inspected. A series of closely spaced apertures or slots 54 are provided in fixed conduit member 16 to permit visual inspection of weld seam 60 by camera assembly 52. The slots may be transverse, as depicted, or longitudinal. As depicted, flexible hose member 18 terminates in roller assembly 34 which has affixed to it camera assembly 52. Camera assembly 52 is provided at its other end with another roller assembly 34. Electrical power for camera assembly 52 and means for receiving signals from the camera are provided by a conduit member 56 which is located internally and coaxially with flexible hose member 18. Camera assembly 52 comprises a housing 62 which is provided with openings 64 and 66 each of which are sealed with a transparent material, typically glass. Located within housing 62 is a camera 67 having a lens 68 facing an inclined mirror 70 to permit a viewing through opening 64. Camera 67 also includes a light source 72 for illuminating the area to be inspected through opening 66 in housing 62. Roller assembly 34 typically comprises a hollow body member 74 for supporting a plurality, generally four, of roller members 76 which are rotatably mounted on hollow body member 74 by pins 78. The roller assembly 34 located on the terminal end of housing 62 has the downstream end of hollow body member 74 closed off, for example by a plug 80. In some applications it may be advantageous to have roller member 76 spring-loaded in a direction radial to fixed conduit member 16 to minimize the risk of binding in the event that there is some nonuniformity in the diameter of fixed conduit member 16. Also, in some instances it may be advantageous not to recirculate the pressurizing fluid or cooling fluid. In such instances housing 62 may also include some provision for venting the fluid to the annular space between vessels 12 and 14. During construction of, for example, a nuclear reactor, a predetermined number of rigid fixed conduit members 16 will be placed in the annular space between vessels 12 and 14 to provide access to the areas which require visual inspection. Typically they may be placed along the length of weld seams on the vessels. A series of closely spaced apertures are provided in fixed conduit member 16 adjacent the surface of area to be inspected. When slots 54 are transverse to the axis of fixed conduit member 16 as shown, the width of the slot must, of course, be less than the diameter of roller members 76 to prevent the roller members from becoming stuck in the slots. In performing the inspection, drive assembly 20 and spool 22 are positioned adjacent the upper end of a selected rigid conduit member 16. Generally the upper end of fixed conduit 16 adjacent the upper portion of vessels 12 and 14 is closed off during normal reactor operation to isolate the annular space between the vessels from the environment. After such closure is removed, flexible hose member 18 and camera assembly 52 are introduced into the upper end of fixed conduit 16 and driven by drive wheel 30 to the area to be inspected. In accordance with the present invention a pressurizing fluid is introduced into flexibile hose member 18 to provide a desired amount of rigidity to facilitate driving it through fixed conduit 16. Generally in case of a nuclear reactor, it also is necessary to provide a coolant to the camera to maintain it within a functional operating temperature range. The coolant also may be supplied by another conduit 56. It is preferred that the coolant and pressurizing fluid be one and the same. Electrical power and return signals from the television camera are provided by additional conduit members 56 also placed within and coaxially with flexible hose member 18. Advantageously the signals coming from the camera are displayed on a T. V. screen for viewing during the inspection and additionally are recorded for comparison with subsequent inspections. To permit subsequent inspections to be more meaningful, drive assembly 20 also may be equipped with a means for recording the length of flexible hose member 18 which has been inserted into conduit 16 as well as the rotational direction the camera is facing, i.e., whether it is facing primary vessel 12 or containment vessel 14. Thus inspections made at different times are readily compared to assist in determining if any potential defects exist. While the present invention has been described in terms of a specific example and what is now considered its best mode of practice, it will be appreciated by those skilled in the art that various changes and modifications are possible which will not depart from the spirit or scope of the inventive concepts taught herein. Thus, the invention has been described, for example, with respect to a camera using a conventional light source. However, it will be appreciated that it is within the scope of the present invention to utilize a camera which receives other types of electromagnetic radiation for display and recording. An example of such a camera would be one which was sensitive to nuclear radiation instead of light. A source of such radiation would then be provided, which source could be radiation from the core of a nuclear reactor. Alternatively a camera could be utilized which responded to infrared radiation from a heat source, which again could emanate from the reactor core. Accordingly, while the invention has been described with respect to a particularly preferred application, in a nuclear reactor, it will have application to any other system or apparatus where inspection is required but, for reasons of temperature, space or radiation, such areas are inaccessible to personnel. Thus, the foregoing description and example are intended to be illustrative only and should not be construed as limiting the scope of the invention, reference being made to the appended claims for this latter purpose.
045308128	description	DETAILED DESCRIPTION OF THE INVENTION Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawing. FIG. 1A is a plane view of a typical segmented coil in accordance with the present invention. Segment 10 of the TF coil 21 is preferably made of copper or copper alloy and is located on the side of the TF coil closest to the main axis 13 of the TFR. Preferably, the segment 11 is made of aluminum or aluminum alloy and is located on the side of the TF coil furthest from the main axis 13 of the TFR. Region 22 in FIG. 1A is the toroidal plasma region The segments 10 and 11 of the coil 21 are joined at joint 12 which is more fully described in connection with FIGS. 2A-C, 3 and 4 below. As can best be appreciated from FIG. 1B, TF coil 21 is only one of a plurality of TF coils that together form the TF generating means 20. The TF coils 21 are insulated from each other with a layer of insulation 19. Preferably, in the region where the adjacent TF coils are in physical contact with each other, (on the side closest to the major axis of the TFR), the layer of insulation is the only material separating the adjacent TF coil windings. It should be understood that in accordance with one aspect of this invention, the blanket means 23 and the shielding means 26 are positioned radially outside of the TF coils 21 from the plasma fusion region 22 and as will be appreciated by one of skill in the art, the blanket may contain a region 24 for breeding tritium as fuel for fusion reactors and/or a region 25 for breeding fissile fuel for fission reactors. The blanket means is also heated by nuclear heating caused by fusion neutrons from the fusion reactions which may occur in the fusion plasma region 22. The blanket means is cooled with coolant from feed line 27, which passes through coolant channels 29 in the blanket and to the coolant return line 28. The TF coils are also cooled with coolant from feed line 30, through TF coolant channels 32 and to the coolant return line 31. Coolant means for the TF coils and blanket are well known in the art and do not form a part of the instant invention. Applicants have found that the joints 12 between the coil segments 10 and 11 must preferably meet the following requirements: 1. Preferably, their mechanical strength in tension and their fatigue endurance must be as great or nearly as great, as that of the weaker of the two metals (aluminum in this case). 2. Preferably, their electrical resistance must be sufficiently small that they are not excessively heated by I.sup.2 R losses. 3. Preferably, they must be sufficiently compact to fit the geometry of the XBTFR. More particularly, they must not protrude from the broad sides of the conductor segments or from the inner edge of the segments facing the plasma fusion region. 4. Preferably, they must not interfere with the removal of heat from the TF coils in their vicinity by the cooling system. Applicants have found that the preferable types of joints that meet these requirements are mechanical joints and metallurgical joints. As will be apparent to one of skill in the art, the metallurgical joints may preferably include soldered joints, brazed joints, fusion welded joints or solid state bonded joints. Preferably, in the case of a mechanical joint, the contact area of the joint is much larger than the cross-sectional area of the conductor segments so as to minimize the electrical resistance of the joint. In accordance with the present invention, the joints can be formed parallel to the face 33 of the TF coils 21 as in FIGS. 2A-2C or they can be in the broad plane 34 of the TF coils 21 as shown in FIG. 3 and FIG. 4. It should be understood that any of the joints formed in accordance with the present invention can be formed either parallel to the face 33 of the TF coil 21 or in the broad plane 34 of the TF coil 21. Preferably, one way to achieve the necessary mechanical joint is depicted in FIG. 2A. The joint consists of an angled lap joint 12A held together by one or more fastening means 15, preferably screws. An angled lap joint can alternately be formed in the broad plane 34 of the TF coil 21. This joint will, with sufficiently large clamping pressure, achieve the necessary low electrical resistance. The tensile stresses of the joint are transmitted by friction between the contacting surfaces 35 and 36 and by the shearing force on the fastening means 15. Alternately, the facing surfaces 37 and 38 can be serrated as depicted in FIG. 2B with serrations formed of alternating positive and negative angular surfaces. Of course, it should be understood that the angles of the adjacent surfaces forming the serrations can be varied over any amount desired and the angle of the serration need not remain constant throughout the length of the joint. It should also be appreciated that adjacent legs along the serrated surface need not be of equal length but can be different. Preferably, however, the facing surfaces 37 and 38 are negative images of each other to provide good contact mating. In FIG. 2C a variation on the serrated surface of FIG. 2B is depicted wherein one side of each pair of angled surfaces forming the serrations has a portion 41 vertical to the broad plane of the TF coil 21 and an angled portion 40 that extends between consecutive vertical portions. Preferably, the joints 12 should be located in a portion of the coil 21 where adjacent coils are separated only by a layer of insulation 18. In those locations the magnetic forces will act to compress the joint thereby reducing the number and size of the fasteners needed to provide the requisite compressive load. It will be apparent to one skilled in the art that the serrated joints described above and depicted in FIGS. 2B and 2C can alternately be placed in the broad plane 34 of the conductors. As depicted in FIGS. 3 and 4, and as discussed above, the joints 12D (in FIG. 3) and 12E (in FIG. 4) may also preferably be positioned in the broad plane 34 of the coil winding as opposed to the joints illustrated in FIGS. 2A, 2B and 2C wherein the joints were positioned parallel to the winding face 33. In the embodiment of FIG. 3, the tensile load on the coil winding 21 is carried by the interlocking teeth 43, the fastening means 16 serving simply to hold the conductor portions in the correct relative orientation. The fastening means 16 may preferably constitute countersunk screw or bolt members that are configured so as not to protrude outside of the smooth contour of the TF coil 21. The contact force required for good electrical conductance is provided by the tensile force, transmitted as a compressive load, across the interlocking tooth surfaces 43. Depicted in FIG. 4 is an alternate embodiment of the interlocking tooth joint. In the embodiment of FIG. 4, the joint is again positioned in the broad plane 34 of the TF coils and preferably is positioned so as to traverse the TF coil 21 generally along a radius of the coil. As a fastening means, a tapered pin 17 may be used, the pin tapering inward toward the inner face of the TF coil 21. In this embodiment, it will be understood by one of skill in the art, both the tensile and compressive contact load are carried by shearing forces in the tapered pin. Several metallurgical fabrication processes may preferably be used to achieve suitable joints 12 for the TF coils 21. It has been found that suitable joints may be formed by one or more of the following processes: welding; including but not limited to gas-metal arc welding; gas-tungsten arc welding; plasma arc welding; shielded metal arc welding; electron beam or laser beam fusion welding; seam or flash resistance welding; bonding, including but not limited to pressure, diffusion, explosive, ultrasonic, magnetic, friction or roll bonding; soldering or brazing using filler metals. In the case of a metallurgical joint, the electrical resistence of the joint will be no greater than that of the parent metals, thus as will be understood, it is not necessary for electrical conduction reasons that the joints have a large contact area. However, as will be readily appreciated by the artisan, a relatively small surface area joint may be mechanically weaker than the parent metals. Therefore, it is preferable to use a large area joint, such as the lap joint of FIG. 2A or such other large area joints as this description will suggest to the artisan, to spread the mechanical load over an area much larger than the cross-sections of the TF coil, thereby reducing the local stress on the joint. Of course, it should be understood that with a metallurgical joint, the fastening means, which may preferably be countersunk screws as illustrated in FIGS. 2A-2C, could be dispensed with. Of course, in the case of the large area interlocking tooth joint that utilizes a tapered pin such as that depicted in FIG. 4, the tapered pin could be eliminated if a metallurgical joint were formed. The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifictions and variations are possible in light of the above teaching. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
	description	This application claims the benefit of U.S. provisional patent application No. 60/867,223, filing date 27 Nov. 2006, hereby incorporated herein by reference, invention title “Doping of Oxygen- and Carbon-Containing Materials by Nuclear Transmutation Using High Energy 3-He Ion Beams,” joint inventors Noel A. Guardala, Ian Patrick Wellenius, Jack L. Price, John F. Muth. The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor. The present invention relates to semiconductor materials, more particularly to methods and systems for doping or otherwise changing the physical character of semiconductor materials. Conventional doping methodologies include (i) ion implantation, (ii) diffusion, and (iii) incorporating dopant atoms during the semiconductor growth. Ion implantation is typically carried out using a dedicated implanter that accelerates ionized dopant species toward the semiconductor material, with energies typically in the 100-1000 keV range. Diffusion is typically accomplished using a high temperature furnace, with either a gas source or a solid source for the dopants; the high temperatures allow dopants to diffuse into the material. Ion implantation, diffusion and similar processes have been limitedly successful in doping wide bandgap materials, including zinc oxide (ZnO), diamond and others. These conventional approaches have not enjoyed complete success for some modern electronic materials because of defect production and/or poor site activation. Ion implantation is an inherently destructive process, creating significant damage in the target material lattice, which must be annealed to produce a quality material. Several materials (silicon carbide, diamond, etc.) anneal at extraordinarily high temperatures, thus making an ion implantation process difficult and costly. Diffusion can be difficult due to the high thermal requirements of certain materials. In addition, defects in materials such as ZnO can lead to self-compensation. It is therefore desirable in the semiconductor and related arts to devise a doping methodology that is not intrinsically destructive. This quality of non-destructiveness could have a significant positive impact on several industries, including high power electronics, solid state lighting, ultraviolet (UV) light detection, and transparent coatings. In view of the foregoing, an object of the present invention is to provide an inherently non-destructive doping methodology. A further object of the present invention is to provide such a doping methodology that is practical and cost-effective. Great difficulty has been encountered in conventional approaches to doping semiconductor films (e.g., ZnO films) to produce p-type material. This difficulty is largely associated with donor-like defects (e.g., oxygen vacancies and zinc interstitials in ZnO material) that easily form during deposition or processing. As distinguished from conventional doping methodologies, the inventive methodology does not encourage compensating defect formation. The present invention provides a novel methodology for altering the physical character of a material such as a semiconductor material. In accordance with typical embodiments of the present invention, semiconductor materials are doped by nuclear transmutation using high energy 3He ion beams. Conventional doping methodologies, such as ion implantation and dopant diffusion, have been less than entirely successful because of their destructive nature and their difficult and expensive implementation. In contrast, the present invention's methodology is inherently non-destructive and is relatively easy and inexpensive to practice. Conventional methodologies involve the insertion of atoms into a material in order to change the material's physical character in one or more respects. As distinguished from conventional methodologies, the inventive methodology involves the transmutation of atoms already existing in the material in order the change the material's physical character in one or more respects. The present invention provides a unique methodology for the electronic doping of semiconductor materials using 3He ion beams. In sum, the present invention as typically practiced provides for nuclear transmutation of the target material via irradiation thereof by high energy 3He ion beams. A material sample is provided that includes atoms that are nuclearly transmutable via bombardment by helium three ions. A beam of energetic 3He ions is emitted so as to be incident on the target material. The beam causes a nuclear reaction in the target material whereby the target species is transmuted to another species. The present invention is typically embodied as a method for changing the physical character of a material, such as a semiconductor material. The inventive irradiation typically results in changing one or more of the following physical characteristics of the material sample: electronic carrier concentration (e.g., generation of p-type carriers, thereby increasing the concentration of p-type carriers); electronic carrier type; resistivity; photoconductivity; luminescence; morphology. Which and to what extent physical characteristics are inventively altered may relate to the material of the sample; for instance, SiC is generally not considered a strong source of luminescence. Two notable genres of the inventive methodology involve (i) the electronic doping of oxygen-containing materials using 3He ion and (ii) the electronic doping of carbon-containing materials using 3He ion beams. The present inventors experimentally demonstrated the efficacy of the present invention with respect to the first above-stated genre of the present invention's methodology, viz., involving the electronic doping of oxygen-containing materials using 3He ion beams. In their testing the present inventors used the Tandem Pelletron Positive—Ion Accelerator Facility (PIAF) at the Naval Surface Warfare Center, Carderock Division (NSWCCD), located in West Bethesda, Md. The Tandem Pelletron PIAF includes a particle accelerator that accelerates negative ions to a positive potential (up to a maximum positive potential of three million volts), strips electrons from negative ions, and then accelerates the resultant positive ions towards a ground potential. Included in the Tandem Pelletron PIAF are an energy/charge-selection magnetic component and a pumping component. This particle accelerator facility is capable of accelerating most atomic species with energies from 0.3 to 30 MeV. Among the possible applications of this particle accelerator facility are material modification through doping with foreign ions, and material characterization by a variety of ion beams. In accordance with frequent inventive practice, either an oxygen-containing material (e.g., zinc oxide) or a carbon-containing material (e.g., silicon carbide) is doped via 3He transmutation. According to an inventive oxygen-to-nitrogen transmutation, 16O is transmuted to 15N; more specifically, 16O is initially transmuted by 3He ion beam bombardment to 15O, which in turn decays by positron emission to 15N. The transmuted element (i.e., oxygen-to-nitrogen in the case of an oxygen-containing material such as ZnO) acts as an electronic dopant in the host semiconductor. According to an inventive carbon-to-boron transmutation, 12C is transmuted to 11B; more specifically, 12C is initially transmuted by 3He ion beam bombardment to 11C, which in turn decays by positron emission to 11B. The transmuted element (i.e., carbon-to-boron in the case of a carbon-containing material such as SiC) acts as an electronic dopant in the host semiconductor. The half lives for 15O and 11C are 124 seconds and 20.38 minutes, respectively. The present invention's 3He transmutation doping affords several advantages over conventional doping methodologies, among which are less lattice damage near the active region, and reduced interstitial dopants. Further, the inventive doping methodology is capable of doping materials that, according to conventional methodologies, are very difficult to work with. In accordance with typical inventive practice, lattice damage is significantly reduced in the vicinity of the active region, since nuclear scattering rarely occurs at such high energies. Because nuclear scattering occurs at much lower energies, such nuclear scattering events, if they occur, tend to occur far away from the active region. For instance, in cases involving thin films, the nuclear scattering region may be distanced well into the substrate material. Generally, when the present invention's high energy bombardment is effectuated, the transmutation that is brought about in the active region has concomitant therewith only a small amount of momentum transferal to the lattice, due to the high mass difference between the incident ion and the target nucleus. Furthermore, according to typical embodiments of the present invention, the material is doped by transmuting a nucleus that is already on the lattice site; therefore, most of the dopants will remain on or near their original lattice site. It is possible that enough momentum would be transferred to the target nucleus during the transmutation that the transmuted species would be dislodged from the lattice; nevertheless, even if this were to occur, the distance that the dislodged transmuted species would travel from its site would be very small. This inventive attribute of “staying home or close to home” reduces the amount of annealing required to produce quality doped material, and facilitates the production of devices based on these materials. An additional advantage of the present invention over implantation and diffusion lies in the superior quality of the resultant doped layer. Because of the uniformity of the cross section over a range of beam energies, the present invention's doping via 3He transmutation produces a relatively thick and relatively uniform doped layer in the material. In contrast, according to diffusion, the bulk of the dopants will inevitably be near the surface through which they enter, and a density gradient will occur through the thickness. Ion implantation produces more uniform layers than does diffusion, but requires implanting at multiple energies to produce thick layers; this is because the implantation profile is a function of both the stopping power of the target material and the initial ion beam energy. In the present invention's 16O (3He, 4He) 15O reaction, the transmutation and decay process ultimately produces atomic nitrogen (N), as opposed to molecular nitrogen (N2). N2 complexes are energetically stable and can be highly unpredictable in their electronic behavior. Due to their stability, N2 complexes are very difficult to anneal once they are in the material and, as such, are highly undesirable. Thus, in order to avoid these stable complexes, it is generally important in practice of this inventive genre to use sources of atomic nitrogen, rather than sources of molecular nitrogen, for doping electronic materials. The inventive methodology is and will be a viable option for existing and newly discovered materials. Traditional methodologies such as ion implantation and diffusion will remain an option for newly discovered materials, but will require significant study and improvement in order to minimize defect production and optimize material performance. While annealing is possible for most materials, higher temperatures make extensive annealing very costly, especially in terms of mass production of devices. 3He (also referred to herein as “helium three” or “helium-3”) is an isotope of helium that contains two protons and one neutron. 3He occurs in nature much more rarely than the most prevalent isotope of helium, namely, 4He (also referred to as “helium four” or “helium-4”), which contains two protons and two neutrons. Typical embodiments of the present invention's nuclear transmutation doping provide for 3He ion transmutation doping; otherwise expressed, the present invention effectuates doping using a beam composed entirely of helium three ions. The present inventors have considered an alternative mode of the present invention's ion beam nuclear transmutation doping, namely, that which involves proton transmutation doping—that is, doping using beams of protons, rather than beams of whole atoms that are ions. As elaborated upon in the next paragraph, the present inventors believe that their 3He ion transmutation doping concept is superior to their proton transmutation doping concept in several respects. A major drawback to proton transmutation is that the reactions typically occur only for rare isotopes, such as 13C, 15N, or 18O. While the cross sections may be quite high, the natural paucity of the reactive isotopes will tend to result in very small dopant yields. By comparison, 3He transmutations are known to occur with several common isotopes, such as 12C and 16O. Furthermore, the cross sections associated with the inventive 3He transmutation doping are similar in magnitude to those associated with the inventive proton transmutation doping, but will ultimately yield higher dopant concentrations. Moreover, proton transmutation doping typically results in a thin doped region, due to the resonant nature of the cross section for proton interaction. In contrast, the cross section for an inventive 3He interaction is typically quite broad, and hence a thicker doped region of similar density will be produced. In fact, a 3He interaction cross section may be broad enough to create uniform doping through the full thickness of a thin film. Aspects of the present invention are disclosed by the following paper, incorporated herein by reference: Ian Patrick Wellenius, Anuj Dhawan, John F. Muth, Noel A. Guardala and Jack L. Price, “Improved Photoconductivity of ZaO by Ion Beam Bombardment,” Materials Research Society Symposium Proceedings, Volume 891, pages 473-478, Materials Research Society (MRS), Warrendale, Pa., 2006, Symposium held Nov. 28-Dec. 1, 2005, Boston, Mass. Aspects of the present invention are also disclosed by the following master's thesis, incorporated herein by reference: Ian Patrick Wellenius, “Nitrogen Doping and Ion Beam Processing of Zinc Oxide Thin Films,” master of science degree, electrical engineering graduate program, date of defense 14 Dec. 2005, URN etd-01042006-015801; available online on or after 14 Dec. 2005 on the ETD (Electronic Theses and Dissertations) web page of North Carolina State University. Other objects, advantages and features of the present invention will become apparent from the following detailed description of the present invention when considered in conjunction with the accompanying drawings. In its basic principle, the present invention effects nuclear transmutation doping (NTD), according to which a nuclear reaction is induced using an energetic ion incident on a lattice atom, thereby producing an atom of a different species in the material. The present invention uniquely features the utilization of high energy 3He ion beams to bring about nuclear transmutation of materials. Of particular interest to the present inventors is their novel use of high energy 3He ion beams to effectuate nuclear transmutation of zinc oxide, whereby nitrogen is produced from a reaction with oxygen in a crystalline ZnO thin film. As elaborated upon hereinbelow, the present inventors successfully tested this mode of inventive practice and found that, vis-à-vis the original zinc oxide films, the inventively doped zinc oxide films were significantly different in terms of resistivity, photoconductivity, scanning electron microscopy, cathodoluminescence, and ion beam analysis. Of particular note, the inventively irradiated zinc oxide films exhibited increased resistivity, increased photoconductivity, and decreased defect luminescence. The latter two findings were consistent with the observed increases in resistivity. ZnO thin films were grown on c-plane sapphire substrates by pulsed laser deposition (PLD) using a Neocera Pulsed Energy Deposition system at North Carolina State University, located in Raleigh, N.C. The zinc oxide films were subsequently annealed to produce resistive material. The PLD system utilizes a KrF excimer laser, pulsing at 10 Hz with an estimated energy density up to 4 J/cm2. Films were grown at 700° C., with an oxygen partial pressure of 35 mTorr for 36,000 pulses. Although substrates made of sapphire were utilized in the inventive testing, inventive practice lends itself to substrates made of a variety of suitable materials. The zinc oxide films that were used for the testing of the present invention were annealed by the present inventors for 8 hours in air at 800° C. Previously, the present inventors conducted a study of time-dependent annealing in order to select a suitable duration for the annealing of the zinc oxide films. Their time-dependent annealing study demonstrated that excessively long annealing at 800° C. caused substantial degradation in film quality. In this study, films were annealed in air, using a quartz tube furnace. It was observed that resistivity and surface morphology improved substantially within the first 3 hours of annealing, and continued to improve marginally with successive anneals. Rutherford backscattering spectroscopy (RBS) data showed that optimal stoichiometry was achieved after 15 hours of annealing, before the films began to deteriorate. Reference is now made to FIG. 1 and FIG. 2. After annealing, the zinc oxide films were irradiated at the Positive Ion Accelerator Facility (PIAF) of the Naval Surface Warfare Center Carderock Division (NSWCCD) in West Bethesda, Md. The PIAF operates a 3 MV National Electrostatics Corporation tandem pelletron accelerator that is equipped with a radio frequency (RF) source for making ion beams from gaseous elements (H, He, N), and a cesium sputtering source for producing ion beams from a variety of solid cathodes. A ninety degree analyzing magnet, controlled by nuclear magnetic resonance (NMR), allows precise definition of the mass-energy of the ion beam. Assorted experimental beam lines are equipped to monitor gamma rays, backscattered particles and x-rays for a variety of ion beam analyses, including Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), and particle induced x-ray emission (PIXE). A particle accelerator is an electrical device that accelerates to high energies either charged atomic particles (e.g., positively or negatively charged ions), or charged subatomic particles (e.g., protons or electrons). A particle accelerator can, at least in theory if not in practice, accelerate any atomic particle (e.g., charged ion) from among the variety of elements and corresponding isotopes in the periodic table of elements. A typical tandem electrostatic accelerator has two phases of acceleration, viz., a first phase of attracting negatively charged ions, and a second phase of repelling positively charged ions. In operation of the tandem accelerator, negatively charged ions gain energy by attraction to a high positive voltage. Electrons are then stripped from the negatively charged ions, which consequently become positively charged ions. The positively charged ions are then accelerated away by the high positive voltage. Positively charged 3He ions are practiced in accordance with typical embodiments of the present invention. A tandem accelerator is one of several kinds of particle accelerators that can be used in inventive practice to generate a beam of 3He ions. According to some embodiments of inventive practice, a tandem accelerator will operate so as to acceleratively input negatively charged helium-3 ions and acceleratively output positively charged helium-3 ions. Negatively charged helium-3 ions (helium-3 atoms characterized by more electrons than characterize a neutrally charged helium-3 atom) are attracted to a high positive voltage and are stripped of some of their electrons so as to become positively charged helium-3 ions (helium-3 atoms characterized by fewer electrons than characterize a neutrally charged helium-3 atom). The positively charged helium-3 ions are repelled by the high positive voltage. According to typical inventive practice, each 3He ion that is beamed upon a material sample (e.g., material entity 50 shown in FIG. 1 and FIG. 2) is a positively charged helium-3 atom that is characterized by fewer electrons than characterize a neutrally charged (nonionic) helium-3 atom. In the inventive testing, a 6.6 MeV 3He ion beam was used to induce two nuclear reactions, viz., a nitrogen-producing reaction (shown in FIG. 1) and a fluorine-producing reaction (shown in FIG. 2), in zinc oxide films. The ZnO films were irradiated by the 3He ion beam using NSWCCD's tandem accelerator, diagrammatically depicted in FIG. 1 and FIG. 2 as particle accelerator apparatus 100, which included an irradiation chamber 101. The target entity 50, which included a substrate 51 and a zinc oxide film 52 situated upon substrate 51, was appropriately situated in chamber 101 for bombardment by 3He ions. As a result of the irradiation by 3He ions, two nuclear transmutations took place. As illustrated in FIG. 1, the nitrogen-producing nuclear reaction was 16O (3He, alpha) 15O, where the oxygen isotope decays to 15N by positron emission. As illustrated in FIG. 2, the fluorine-producing nuclear reaction was 16O (3He, 1H) 18F. The fluorine-producing reaction was similar to the nitrogen-producing reaction and occurred simultaneously therewith. In the fluorine-producing reaction, the unstable fluorine isotope decays also by positron emission to 18O. Thus, there is a null net effect from the fluorine-producing reaction. The unstable fluorine isotope that is produced as shown in FIG. 2 decays with a half life of 110 minutes; therefore, after about 30 hours, the fluorine population has decayed to one millionth of its maximum. Accordingly, the ZnO films were actually doped using the reaction 16O (3He, alpha) 15O, where the product decays by positron emission to 15N with a half life of 124 seconds. The irradiations were initially carried out in a chamber 101 that was equipped with a particle detector to monitor the emission of alpha particles due to the reactions. However, high levels of neutron and gamma emission required that the zinc oxide films be irradiated in a shielded chamber 101, and the only such chamber at the PIAF is not designed for particle detection. With reference to FIG. 3 and FIG. 4, the zinc oxide films 52 were each irradiated for a duration in the range between 4 and 6 hours, the irradiation ranging in total dose from 8.5 to 17.1 mC. As indicated in FIG. 4, this yields an estimated nitrogen density in the approximate range between (1×1014 cm−3) and (3×1014 cm−3). It can generally be said that the cross-sections of the present invention's two nuclear transmutations reactions that are respectively shown in FIG. 1 and FIG. 2 are rather strong and broad, as compared to other nuclear transmutation reactions that may occur in nature. FIG. 3 illustrates cross sections characterizing the two nuclear transmutation reactions associated with the inventive irradiation, using 3He ion beams, of an oxygen-containing material such as zinc oxide (ZnO). As illustrated in FIG. 3, the peak cross section of 169 mb for the nitrogen-producing reaction, the reaction of real interest, occurs near 6.6 MeV ion beam energy. The fluorine-producing reaction peaks at a slightly lower ion beam energy, but with a much higher peak cross section of 436 mb; again, this is of little concern, as the 18F product rapidly decays to 18O. FIG. 3 also illustrates cross sections characterizing the three nuclear transmutation reactions associated with the present invention's conceptual irradiation, using 3He ion beams, of a carbon-containing material such as silicon carbide (SiC). Four-point probe resistivity measurements were performed of the irradiated zinc oxide films. The resistivity measurements were taken of the irradiated zinc oxide films using a Lucas 307 probe station and a Signatone 4-point probe head with rounded osmium tips, spaced 1 mm apart. A Keithley 220 programmable current source was used to drive a current through the sample, and the resulting voltage was measured by a Keithley 6517a high-impedance electrometer. The resistivity of the zinc oxide films increased from between 50 and 135 ohm-cm, before irradiating, to between 450 and 500 ohm-cm, after irradiating. This was observed by measuring a control sample and by comparing the resistivity of the films in the irradiated and unirradiated portions. Cathodoluminescence (CL) emission was measured using an Oxford MonoCL monochromator with a liquid-cooled photomultiplier tube (PMT) attached to a JEOL JSM-6400 thermionic emission scanning electron microscope (SEM). Reference now being made to FIG. 6, the green-yellow cathodoluminescence (CL), which can be attributed to point defects in ZnO, was observed to decrease substantially in the irradiated portions 52R of the zinc oxide films, as compared to the unirradiated portions 52N of the zinc oxide films 52. The changes in resistivity and CL emission are most likely caused by ion beam annealing, since the doping concentration of the films by nitrogen is too low to be expected to appreciably compensate the films. MeV-range light ion beams have been observed to anneal point defects in silicon; see O. W. Holland, “Interaction of MeV Ions with Pre-Existing Damage in Si: A new Ion Beam Annealing Mechanism,” Applied Physics Letters, Volume 54, Number 4, pages 320-322 (23 Jan. 1989), incorporated herein by reference. Similar mechanisms may be at work in the irradiated ZnO films, which may anneal the point defects typically associated with n-type conductivity. With reference to FIG. 7 and FIG. 8, scanning electron microscope (SEM) imaging and cathodoluminescence imaging of the inventively irradiated zinc oxide films were performed. When viewed with an SEM, the irradiated region of the film is easily discerned from the rest of the film surface due to a change in electron emission, as shown in FIG. 5. This is likely caused by the change in resistivity of the film by affecting how the film surface dissipates the charge from the electron beam. As positive charge accumulates on the more resistive surface, secondary electrons are less likely to escape the film surface and reach the detector, causing a darker appearance. In general, the morphology of the films was not dramatically altered by the inventive ion beam process. One micron and five micron atomic force microscope (AFM) micrographs did not depict any measurable change in the surface roughness or morphology due to irradiation. However, as shown in FIG. 8 through FIG. 11, micron-sized circular features were observed on some of the irradiated films and across the entire surface of one film. To further study the nature of these features, a diamond scribe was used to lightly scratch the film surface and the damaged features were observed in the SEM. The SEM micrographs indicate that the structures have collapsed entirely as opposed to simply fracturing, which indicates that the round features were likely hollow or gas-filled rather than solid ZnO that may have expanded. A CL image of one round feature, taken at 320 nm, demonstrates that there is no remaining ZnO film beneath the collapsed structure. That particular emission wavelength was chosen because sapphire has a defect state that emits near 320 nm, which cannot be confused with any ZnO emission. A similar CL image was taken of the same feature at 1 keV to demonstrate that there is no significant ZnO film remaining on the substrate where the feature used to exist. The range of the electron beam through ZnO at 1 keV is 10-15 nm. Radiation blistering was observed in a previous study, in which materials were implanted with MeV-range H or He ions; see R. Behrisch, J. Bottiger, W. Eckstein, U. Littmark, J. Roth and B. M. U. Scherzer, “Implantation Profiles of Low-Energy Helium in Niobium and Blistering Mechanism,” Applied Physics Letters, Volume 27, Number 4, pages 199-201 (1975), incorporated herein by reference. Behrisch et al. reported that there is a minimum critical dose required for blister formation, and suggested that the blisters are created by ion beam induced stresses. These stresses cause the H or He ions to migrate towards the surface, forming bubbles underneath the surface, which causes blister-like features; see X. Weng, W. Ye, R. S. Goldman and J. C. Mabon, “Formation and Blistering of GaAsn Nanostructure Layers,” Journal Of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, Volume 22, Number 3, pages 989-992 (May 2004), incorporated herein by reference. As the ions coalesce at the interface, they form bubbles or gas pockets, applying a pressure on the surface film, which causes the film to separate in some places from the substrate. Photoconductive detectors were fabricated in the inventive testing by depositing 200 nm thick aluminum contacts on the ZnO film surface in an interdigitated finger structure. The fingers were spaced 3, 5, 10 and 20 microns apart in each of the four device sizes. Transfer length method (TLM) measurement structures such as shown in FIG. 5 were also deposited upon the ZnO film surface, but were not used in the inventive testing. Dark and illuminated current-voltage measurements were taken using a parameter analyzer, and the samples were illuminated using a small mercury lamp. The spectrally resolved photo-response was characterized using an Oriel illuminator and monochromator, equipped with a xenon lamp. Again, the Keithley 220 current source was used to bias the devices, and the Keithley 6517a electrometer was used to measure the voltage. With reference to FIG. 12 through FIG. 14, the current-voltage (I-V) curves reiterate the increase in resistivity of the irradiated films as compared to unirradiated films. Furthermore, the irradiated films demonstrate a substantial increase in response to excitation from a mercury lamp. The spectrally resolved photoconductivity data confirms this trend, as the irradiated zinc oxide films show a stronger response to near-band edge and above illumination than do the unirradiated zinc oxide films. The inventive testing that was conducted involving inventive irradiation of zinc oxide films suggests that nuclear transmutation using high energy 3He ion beams is a viable alternative for doping ZnO. Although the inventive testing described hereinabove was conducted with respect to oxygen-containing materials, the inventors believe that invention principles are transferable at least with respect to carbon-containing materials, and quite probably with respect to materials containing other transmutationally operative elements. The inventive irradiation of ZnO films by 6.6 MeV 3He ions for several hours caused substantial improvement in the optical and electrical behavior of the zinc oxide films. A plausible cause for the observed optical and electronic changes in irradiated films is ion-beam induced annealing of point defects. Moreover, surface morphology was altered in terms of the formation of micron-sized blisters caused by the irradiation. The inventively achieved 15N concentration in the zinc oxide film is believed to be detectable, but is likely too low to detect through commonly available techniques. Further investigation of the present invention can be made. For instance, investigation involving defect analysis by positron annihilation spectrometry (PAS) and channeling RBS measurements can be made to study the ion-beam induced annealing mechanism in ZnO. Further, correlation of defect analysis and crystallography data with inventive irradiation data may lead to unique annealing techniques for ZnO films. In addition, 3He ion beam irradiations of higher current densities and/or longer durations may be carried out to investigate the limits of inventive practice. The present invention, which is disclosed herein, is not to be limited by the embodiments described or illustrated herein, which are given by way of example and not of limitation. Other embodiments of the present invention will be apparent to those skilled in the art from a consideration of the instant disclosure or from practice of the present invention. Various omissions, modifications and changes to the principles disclosed herein may be made by one skilled in the art without departing from the true scope and spirit of the present invention, which is indicated by the following claims.
	summary
	abstract	In a lithographic system, data transmission is carried out by a powerful electro-optical free-beam connection system enabling optical pattern data to be guided from light exit places to light entrance places inside the vacuum chamber by free-space optical beams in order to produce control signals. The burden on the pattern production system is significantly reduced by the disappearance of mechanical and electrical contacts. The paths of the free-space optical beams and the particle beams can intersect each other in a non-influential manner. Active photodiodes acting as light exit places can be spatially disposed directly in the pattern production system. Passive light waveguides which can be bundled together to form multipolar fibre array plugs, or active transmission lasers, either of which can also act as light exit places, can be arranged outside the vacuum chamber.
048511560	summary	BACKGROUND OF THE INVENTION Disposal of nuclear wastes is an important problem in the nuclear energy field today since many radioactive wastes must be stored for very long periods to assure that no health hazard will occur. Low level nuclear combustible solid waste materials are a particular problem because of the relatively large bulk of materials associated with small amounts of contamination. Typical combustible solid waste materials of concern are those resulting from fuel fabrication operations, such as used rubber gloves, paper, rags, metals, glassware, brushes, and various plastic. Of particular concern as well is the disposal of spent ion exchange resins from reactors, fuel fabrication plants, and reprocessing plants, estimated to comprise from 500 to 800 cubic feet of material per year per nuclear reactor. Present practice consists of packaging these solid waste materials in containers ranging from cardboard boxes lined with plastic bags to steel drums, then burying the packages in pits or trenches. This technique involves difficult and expensive handling of the scrap materials, transporting the packaged materials over roadways and finally storing the materials in monitored repositories or burial grounds. Potential release of contamination to the environment is possible as a result of the rapid decay of the containers, or inadvertent combustion, etc. Moreover, in fuel representing plants and fuel preparation plants, spent ion exchange resins contain significant amounts of plutonium as well as other fission products which may preclude direct burial of these resins, and require monitored retrievable storage. A large percentage of the contaminated solid waste material is simply light-weight, bulky combustible material. Incineration of nuclear solid waste materials has been studied extensively, but it is subject to poor control of combustion, with attendant off-gas system difficulties and severe corrosion problems, coupled with rather expensive maintenance problems. Mechanical compaction of the solid waste material has also been studied extensively with volume reductions of two to ten-fold being achieved. In general, however, compaction and sorting of nuclear solid waste materials are moderately expensive in that special personnel protection devices are needed over and above normal protective equipment costs. Also, compacted solids are readily dispersible in the environment and can generate gases which under certain circumstances may constitute a safety hazard until properly disposed of in an engineered controlled and monitored area. Acid digestion volume reduction methods appear to have some advantages over incineration, namely more efficient off-gas handling, and generally better reliability and longevity of essential hardware exposed to radioactive materials. Other advantages include a lack of buildup or accumulation of activity in refractory linings, and no generation of a liquid waste stream requiring further treatment. Combustible waste can be wholly digested with acid to an inert, non-combustible residual fraction. This very high sulfated residue fraction is wet with sulfuric and nitric acids but can be immobilized as a high integrity low leachable and low dispersible glass solid. The method involved removal of the acids, solids milling, desulfation of the residue using carbon fines at 700.degree. to 900.degree. C., and glassification of the desulfated material after adding appropriate glass formers and heating to at least 1050.degree. C. The acid digestion waste treatment combined with a residue immobilization process complete the plant processing cycle. Large volumes of easily dispersible waste solids are converted to a small volume (20% reduction) of non-dispersible product compatible with presently used packaging methods. Conversion of the wastes to a non-leachable, non-dispersible solid is desired in order to provide an added safety factor, and possibly lower ultimate cost, in permanent storage. For some nuclear waste residues, glass-forming additives such as phosphates or borates and lime or magnesia have been employed to obtain a vitreous nonleachable product with good mechanical strength and thermal conductivity. A major difficulty in these processes which form solids containing fission-product contamination has been the tendency of radio ruthenium to volatize, both during evaporation, and calcination, or fusion. For example, in the absence of control measures, ruthenium is normally volatized to the extent of 20 to 60 percent in calcining at the elevated temperatures, i.e., above 850.degree. C., required for producing a ceramic or above 950.degree. C. for a glassy solid. The volatized ruthenium, in the form of fission-product isotopes, ruthenium 103 and ruthenium 106, represents a substantial portion of the gamma activity of these solutions, and off-gas systems are thus severely contaminated. In some solids-forming processes, the volatilized ruthenium has been collected on silica gel or ferric oxide beds and the loaded beds subsequently combined with the calciner product. This procedure, however, is undesirable because of contamination of process equipment and the additional handling of highly radioactive materials required. Other problems preclude addition of phosphates to acid digestion methods due to the serious corrosion problems caused by them. Minimization of nitric acid concentration, pressure, and temperature in evaporation has been employed to minimize volatilization. These measures, however, have not been fully effective in the preparation of glass-like, non-leachable solids where a temperature of at least about 950.degree. C. is required. Ruthenium off-gas losses of 50% or more are common. SUMMARY OF THE INVENTION An acid waste processing and immobilization method has been device that will simplify some of the process transfer and material handling steps of the present system described in a previous section, and which exhibits retention of about 90% of the radio-ruthenium which is volatile in present acid digestion and incineration processes. Combustible nuclear waste is reacted with sulfuric acid at reaction temperatures up to 330.degree. C. The hot sulfuric acid decomposes the waste to gaseous components and carbonized particulates (agitation is also helpful). The carbonized material disperses in the acid to act as a reducing agent that prevents ruthenium from being oxidized to the volatile form. The carbon material also serves a dual purpose of being a reductant for sulfates, and so once the acid is removed from carbonaceous residue, it can be desulfated directly. This simplifies the immobilization portion of the process by eliminating a solids milling an a graphite addition and mixing step. The desulfated residue is then heated to the higher temperature of about 1100.degree. C. and fused into a glass product. PRIOR ART The use of sulfuric acid with a toxic selenium catalyst to reduce the volume of combustible low level radioactive waste is described in "Treatment of Combustible, Solid, Low-Level Radioactive Waste at RISO, the Danish Atomic Energy Commission Research Establishment," by I. Larsen, in the Proceedings of a Symposium or Practices in the Treatment of Low and Intermediate Level Radioactive Waste, IAEA and ENEA, Vienna, December 1965. U.S. Pat. No. 3,957,676 discloses the treatment of nuclear solid waste material with concentrated sulfuric acid at 230.degree. to 300.degree. C. The waste is simultaneously or later treated with nitric acid or nitrogen dioxide. U.S. Pat. No. 3,120,493 discloses the suppression of volatile ruthenium compounds in radioactive waste by treatment with nitric acid by providing phosphite or hypophosphite ion (incompatible in our hardware) to form phosphate glass-like solids at elevated temperatures. DESCRIPTION OF THE INVENTION The combustible nuclear waste material that is treated by the process of this invention consists of gloves, paper, rags, and the like. A typical waste composition is about 35% by weight cellulose, 25% rubber, and 40% plastic. The ruthenium and other radioactive elements in the waste material are generally not in a volatile state, but are volatilized during nitric acid processing or air incineration. It was determined that use of a different acid digestion technique wherein the waste would not be fully digested, but rather reduced to a degraded carbonaceous state, combined with modified immobilization steps could result in a complete waste treatment method with certain advantages over the prior art process. Our new waste treatement-immobilization process includes the following steps: (a) the quantity of glass formers or frit is estimated per unit of waste and is fed into the process concurrently with the waste, (b) the waste is agitated with hot concentrated sulfuric acid (92% at temperatures greater than 250.degree. C.) which converts the waste into particulate carbon material plus inert residue, (c) the acid is removed by centrifugation and evaporation methods, (d) the material is desulfated by heating to 700.degree. to 900.degree. C. until evolution of sulfur dioxide and similar gases ceases, (e) the material is glassified by heating the material to about 1100.degree. C. for at least two hours, and (f) the product is slowly cooled down to room temperature and the glass cannisters packed in drums for removal to a disposal area. The new method eliminates most of the mechanical handling operations of the immobilization part of the prior art process. If the process is also used to treat reactor combustible waste or other wastes with fission-product contamination, our process has the additional advantage of retaining the bulk of normally volatile ruthenium radionuclides in the final glass product. Other common fission-product radionuclides routinely encountered, such as cesium, strontium, cerium, etc. are considered to be reasonably stable in a sulfate, metal oxide, or glass matrix. The amount of concentrated sulfuric acid used should be about 5 to about 12 liters of sulfuric acid per kilogram of waste material. The mixture of waste material and concentrated sulfuric acid should be heated at a temperature near but below the boiling point of the sulfuric acid. A typical temperature range is about 250.degree. to about 330.degree. C. Lower temperatures take too long and higher temperatures require pressurized equipment. The preferred temperature range is about 300.degree. to about 325.degree. C. if appropriate corrosion resistant materials can be found. The waste reacts initially quite rapidly resulting in finely dispersed carbon. A feed state of about 1.5 pounds per hour per gallon of acid is probably realistic. Typically, about 30 minutes are needed for this reaction. The carbon primarily prevents volatile ruthenium compounds such as ruthenium tetroxide from forming and if formed, they are reduced to non-volatile oxides: Ru0.sub.4 +C.fwdarw.Ru0.sub.2 +C0.sub.2 and 4Ru0.sub.4 +5C.fwdarw.Ru.sub.2 0.sub.3 +5C0.sub.2. In the second step of the process of this invention, the excess sulfuric acid is removed from the waste material. Removal is preferably accomplished by evaporation because it treats both dissolved and suspended solids. Evaporation can be enhanced by centrifugation to reduce the energy requirements and recycle the acid faster. The acid that is removed is preferably recovered and is recycled. Evaporation is preferably performed at a temperature of at least about 350.degree. C. as lower temperatures are too slow, and below a temperature of 450.degree. C. because higher temperatures are unnecessary. The next step, desulfating the residue, is considered to be necessary if the waste is contained in glass because a leachable sulfate second phase can occur during glassification if sulfate is not removed. However, for other waste forms such as ceramics, cement, or polymers, desulfating is optional but does improve volume reduction. Desulfating requires a temperature of at least about 700.degree. C., but temperatures in excess of 900.degree. C. should not be used as glazing may prevent removal of the sulfates resulting in a second phase formation during glassification. The residue should be heated until sulfur dioxide is no longer evolved to complete the desulfating step. The sulfate is removed by reaction with the carbon that is present: EQU 2M.sub.x S0.sub.4 +C.fwdarw.2S0.sub.2 +C0.sub.2 +2M.sub.x 0 where M is sodium, calcium, iron, or other metal, and x is 2 divided by the valence of M. In the next step, which is optional, the residue is contained in glass or ceramic. If this step is to be used, glass formers must be added to the residue at any previous step in the process. The glass formers are the reagents used in making glass, i.e., silicon, boron, sodium, and aluminum. The glass is a low leachable borosilicate glass. Typically, 10%, though it may vary from 2 to 20% by weight glass former (based on total solids, including glass former), is needed. The temperature range required for glass formation will depend on the type of glass used, but a range of about 1050.degree. C. to 1150.degree. C. is usually suitable, and a temperature over 1200.degree. C. is unnecessary and may damage the container. The desulfating step and the glassification step can be run concurrently with the same equipment to minimize energy usage. The glass containing the dispersed radioactive residue can be melted directly in cans used for immobilization, and then placed in drums and sealed for storage or disposal.
039309398	claims	1. A gas-coolant nuclear reactor including a core enclosed by a pressure vessel, a melted core intercept basin below the core and a metal containment vessel enclosing the vessel and basin and having a metal top having an outer surface which is exposed to the outside of the top; wherein the improvement comprises means for conducting a fluid coolant cooling a melted core in said basin, from the basin to an extended area of the inside of said top of said metal containment vessel for cooling by the conduction of heat through the containment vessel's wall to the outside of the containment vessel, said top of said containment vessel having double walls between which said conducting means connects. 2. A gas-coolant nuclear reactor comprising a core, a pressure vessel having an inside enclosing said core and an outside, and a basin below said core and positioned to intercept said core in the event the core melts and falls, said pressure vessel forming an enclosure above said basin, a steel containment shell enclosing said pressure vessel and said basin and having a heat-conductive upper portion extending above the pressure vessel and basin, the steel shell's said upper portion having an outside exposed to the atmosphere outside of the containment shell, said upper portion having an inside, ducts connecting with said basin and extending upwardly and opening to the steel shell's said inside and extending from said inside downwardly and back to said basin, and a coolant in contact with said basin for removing heat from said core in the event it melts and falls and is intercepted by the basin, said ducts connecting with said basin to conduct said coolant when thermally rising from the basin, to said inside of said upper portion of said steel containment shell and, when cooled by conduction of heat through said upper portion to its said outside, to conduct said coolant back to said basin, said pressure vessel, said basin, said ducts and said inside of said upper portion of said steel containment shell cooperatively forming a recirculation circuit for said coolant. 3. The installation of claim 2 in which said basin is positioned on the outside of and below said pressure vessel inside of said shell. 4. The installation of claim 3 which said coolant is formed by a gas atmosphere contained between the outside of said pressure vessel and the inside of said shell, and said basin has an inside and an open top directly facing the pressure vessel's said outside, said ducts connecting said gas atmosphere with the inside of said basin. 5. The installation of claim 2 in which said basin is positioned on the inside of said pressure vessel, and a second basin is positioned on the outside of and below said pressure vessel inside of said steel shell. 6. The installation of claim 2 in which said basin is positioned on the inside of said pressure vessel and said coolant is a material which vaporizes under the heat of a melted core falling into said basin, and having means for separating said coolant from the inside of said pressure vessel.
	abstract	A passive reactor cavity cooling system according to the present invention includes: a reactor cavity formed between a reactor vessel and a containment structure enclosing the reactor vessel; a first cooling system to control external air to sequentially pass through an air falling pipe and an air rising pipe provided in the reactor cavity, so that residual heat of a core transferred to the reactor cavity is discharged to the atmosphere; a second cooling system having a water cooling pipe disposed in an inner space of the containment structure or in a wall of the containment structure to discharge the residual heat of the core transferred to the reactor cavity to outside; and a functional conductor having an insulating property in a normal operation temperature range of the reactor and a heat transfer property in an accident occurrence temperature range of the reactor which is a higher temperature environment than the normal operation temperature range, wherein the air falling pipe and the water cooling pipe are disposed behind the air rising pipe with respect to a direction viewed from the reactor vessel, and the functional conductor is disposed between the air falling pipe and the air rising pipe.
	summary
	claims	1. A method for detecting the presence of a radioactive element or a source of radiation, comprising:a) receiving radiation from a radiation source, the radiation impinging upon a scintillator having the formula:AxB2-xO3 wherein A is an element chosen from La, Y, Lu or Sc;B is an element chosen from La, Y, Lu or Sc;provided that A and B are not the same element;the index x is greater than 0 and less than 2 (0<x<2);wherein the impinging radiation causes the scintillator to emit electromagnetic radiation; andb) measuring the resulting electromagnetic emission. 2. The method according to claim 1, wherein the radiation impinging upon the scintillator is from an ultraviolet source and the electromagnetic emission is photoluminescence. 3. The method according to claim 1, wherein the radiation impinging upon the scintillator is from an X-ray source and the electromagnetic emission is X-ray induced luminescence or fluorescence. 4. The method according to claim 1, wherein the scintillator has the formula LaxY2-xO3. 5. The method according to claim 4, wherein the scintillator is chosen from La0.05Y1.95O3, La0.1Y1.9O3; La0.2Y1.8O3; La0.3Y1.7O3; La0.4Y1.6O3; La0.5Y1.5O3; and La0.6Y1.4O3. 6. The method according to claim 1, wherein the scintillator has the formula LaxSc2-xO3. 7. The method according to claim 6, wherein the scintillator is chosen from La0.05Sc1.95O3, La0.1Sc1.9O3; La0.2Sc1.8O3; La0.3Sc1.7O3; La0.4Sc1.6O3; La0.5Sc1.5O3; and La0.6Sc1.4O3. 8. The method according to claim 1, wherein the scintillator has the formula LaxLu2-xO3. 9. The method according to claim 8, wherein the scintillator is chosen from La0.05Lu1.95O3, La0.1Lu1.9O3; La0.2Lu1.8O3; La0.3Lu1.7O3; La0.4Lu1.6O3; La0.5Lu1.5O3; and La0.6Lu1.4O3. 10. A method for detecting the presence of a source of radiation, comprising:a) receiving radiation from an ultraviolet radiation source, the radiation impinging upon a scintillator having the formula:AxB2-xO3 wherein A is chosen from La, Y, Lu or Sc;B is chosen from La, Y, Lu or Sc;provided that A and B are not the same element;the index x is greater than 0 and less than 2 (0<x<2);wherein the impinging radiation causes photoluminescence; andb) measuring the resulting photoluminescence. 11. The method according to claim 10, wherein the scintillator has the formula LaxY2-xO3. 12. The method according to claim 11, wherein the scintillator is chosen from La0.05Y1.95O3, La0.1Y1.9O3; La0.2Y1.8O3; La0.3Y1.7O3; La0.4Y1.6O3; La0.5Y1.5O3; and La0.6Y1.4O3. 13. A device for detecting the presence of radiation, comprising:a) a scintillator having the formula:AxB2-xO3 wherein A is chosen from La, Y, Lu or Sc;B is chosen from La, Y, Lu or Sc;provided that A and B are not the same element;the index x is greater than 0 and less than 2 (0<x<2); andb) a detector for receiving emitted electromagnetic radiation. 14. The device according to claim 13, wherein the scintillator has the formula LaxY2-xO3. 15. The device according to claim 14, wherein the scintillator is chosen from La0.05Y1.95O3, La0.1Y1.9O3; La0.2Y1.8O3; La0.3Y1.7O3; La0.4Y1.6O3; La0.5Y1.5O3; and La0.6Y1.4O3. 16. A method for detecting the presence of a radiation source, comprising:a) contacting a scintillator having the formula:AxB2-xO3 wherein A is chosen from La, Y, Lu or Sc;B is chosen from La, Y, Lu or Sc;provided that A and B are not the same element;the index x is greater than 0 and less than 2 (0<x<2) with a suspected source of radiation; andb) observing whether induced luminescence or X-ray fluorescence florescence occurs. 17. The method according to claim 16, wherein the scintillator has the formula LaxY2-xO3. 18. The method according to claim 17, wherein the scintillator is chosen from La0.05Y1.95O3, La0.1Y1.9O3; La0.2Y1.8O3; La0.3Y1.7O3; La0.4Y1.6O3; La0.5Y1.5O3; and La0.6Y1.4O3. 19. The method according to claim 16, wherein the suspected radiation is in a container. 20. The method according to claim 16, wherein a person has possession of the suspected radiation.
	claims	1. A core catcher for use in a boiling water nuclear plant which has:a base mat;a reactor building built on a part of the base mat;a containment vessel provided in the reactor building, built on the base mat and having a total height of not exceeding 29.5 m to a lower end of a top slab;a core;a reactor pressure vessel holding the core;a dry well constituting a part of the containment vessel and holding the reactor pressure vessel;a pedestal connected to the base mat and supporting the reactor pressure vessel through a vessel skirt and a vessel support;a wet well constituting a part of the containment vessel, the wet well being provided around the pedestal, holding a suppression pool in a lower part thereof, and having a wet well gas phase at an upper part thereof;LOCA vent pipes provided in a sidewall of the pedestal and connecting the dry well to the suppression pool;a lower dry well which is a space in the dry well, is located below the vessel skirt and the reactor pressure vessel and is surrounded by the sidewall of the hollow cylindrical pedestal and the part of the base mat, which lies inside the sidewall of the pedestal;control rod drives provided in the lower dry well and connected to a lower part of the reactor pressure vessel; anda control rod drive handling equipment provided in the lower dry well and below the control rod drives;the core catcher comprising:a main body including:a distributor arranged on the part of the base mat in the lower dry well, a basin arranged on the distributor,cooling channels arranged on a lower surface of the basin, having inlets connected to the distributor and extending in radial directions, anda riser connected to outlets of the cooling channels and extending upward in vertical direction;a lid connected to an upper end of the riser and covering the main body;a cooling water injection pipe connected at an inlet end to the suppression pool, penetrating the sidewall of the pedestal, connected at an outlet end to the distributor, and configured to supply suppression pool water to the distributor; andchimney pipes connected at an inlet end to the riser, penetrating the sidewall of the pedestal, and having an outlet end located above the upper end of the riser and submerged in the suppression pool water at a level lower than a minimum water level at a time of an accident,wherein the upper ends of the main body and the lid are at heights lower than lower end of the control rod drive handling equipment, as measured from upper end of the base mat and positioned lower than a level 1.7 m above the upper end of the base mat,wherein the cooling water injection pipe, the distributor, the cooling channels, the riser and the chimney pipes are kept communicated with the suppression pool at all times, and always filled with the suppression pool water. 2. The core catcher according to claim 1, wherein a refractory layer is provided on an upper surface of the basin and sides of the riser. 3. The core catcher according to claim 2, wherein a sacrificial layer is provided on the refractory layers. 4. The core catcher according to claim 1, wherein the lid does not have a sump or there are no flooding pipes arranged below the lid. 5. The core catcher according to claim 1, wherein the outlet end of each of the chimney pipes opens in the suppression pool at a height equal to or higher than 2.45 m from the upper end of the part of the base mat. 6. The core catcher according to claim 1, wherein at least part of each of the chimney pipes extends upward in vertical direction in the sidewall of the pedestal. 7. The core catcher according to claim 1, wherein at least part of each of the chimney pipes extends upward and slantwise in the sidewall of the pedestal. 8. The core catcher according to claim 1, wherein at least part of each of the chimney pipes extends upward in vertical direction in the suppression pool. 9. A boiling water nuclear plant comprising:a base mat;a reactor building built on a part of the base mat;a containment vessel provided in the reactor building, built on the base mat and having a total height of not exceeding 29.5 m to a lower end of a top slab;a core;a reactor pressure vessel holding the core;a dry well constituting a part of the containment vessel and holding the reactor pressure vessel;a pedestal connected to the base mat and supporting the reactor pressure vessel through a vessel skirt and a vessel support;a wet well constituting a part of the containment vessel, the wet well being provided around the pedestal, holding a suppression pool in a lower part thereof, and having a wet well gas phase at an upper part thereof;LOCA vent pipes provided in a sidewall of the pedestal and connecting the dry well to the suppression pool;a lower dry well which is a space in the dry well, is located below the vessel skirt and the reactor pressure vessel and is surrounded by the sidewall of the hollow cylindrical pedestal and the part of the base mat, which lies inside the sidewall of the pedestal;control rod drives provided in the lower dry well and connected to a lower part of the reactor pressure vessel;a control rod drive handling equipment provided in the lower dry well and below the control rod drives; anda core catcher having:a main body including:a distributor arranged on the part of the base mat in the lower dry well,a basin arranged on the distributor,cooling channels arranged on a lower surface of the basin, having inlets connected to the distributor and extending in radial directions, anda riser connected to outlets of the cooling channels and extending upward in vertical direction;a lid connected to an upper end of the riser and covering the main body;a cooling water injection pipe connected at an inlet end to the suppression pool, penetrating the sidewall of the pedestal, connected at an outlet end to the distributor, and configured to supply suppression pool water to the distributor; andchimney pipes connected at an inlet end to the riser, penetrating the sidewall of the pedestal, and having an outlet end located above the upper end of the riser and submerged in the suppression pool water at a level lower than a minimum water level at a time of an accident,wherein the upper ends of the main body and the lid are at heights lower than lower end of the control rod drive handling equipment, as measured from upper end of the base mat and positioned lower than a level 1.7 m above the upper end of the base mat,wherein the cooling water injection pipe, the distributor, the cooling channels, the riser and the chimney pipes are kept communicated with the suppression pool at all times, and always filled with the suppression pool water.
059303140	abstract	This invention provides coded aperture imaging apparatus and methods for the detection and imaging of radiation which results from nuclear interrogation of a target object. The apparatus includes: 1) a radiation detector for detecting at least a portion of the radiation emitted by the object in response to nuclear excitation and for producing detection signals responsive to the radiation; 2) a coded aperture disposed between the detector and the object such that emitted radiation is detected by the detector after passage through the coded aperture; and 3) a data processor for characterizing the object based upon the detection signals from the detector and upon the configuration of the coded aperture. The method includes the steps of: 1) disposing a coded aperture in selected proximity to the object; 2) bombarding the object with a interrogation beam from a source of excitation energy; 3) detecting, with a detector, at least a portion of the radiation emitted in response to the interrogation beam, the detector producing detection signals responsive to the radiation, the detector being disposed so that the coded aperture is between the detector and the object and such that emitted radiation is detected by the detector after passage through the coded aperture; and 4) processing the detection signals to characterize the object based upon radiation detected by the detector after passage through the coded aperture, and based upon the configuration of the coded aperture.
	description	This application is a continuation-in-part of U.S. patent application Ser. No. 15/584,926, filed May 2, 2017, which application is a continuation-in-part of U.S. patent application Ser. No. 14/981,512, filed Dec. 28, 2015, which application claims the benefit of U.S. Provisional Application Nos. 62/097,235, filed Dec. 29, 2014, 62/098,984, filed Dec. 31, 2014, and 62/234,889, filed Sep. 30, 2015, which applications are hereby incorporated by reference. U.S. patent application Ser. No. 15/584,926 also claims the benefit of U.S. Provisional Application No. 62/330,695, filed May 2, 2016, which application is hereby incorporated by reference. The utilization of molten fuels in a nuclear reactor to produce power provides significant advantages as compared to solid fuels. For instance, molten fuel reactors generally provide higher power densities compared to solid fuel reactors, while limiting fuel fabrication processes, which are necessary in the construction of solid fuels. Molten fuel reactors may also provide a higher level of burn-up in a given reactor, even in systems lacking salt cleanup. Molten fluoride fuel salt suitable for use in nuclear reactors have been developed using uranium tetrafluoride (UF4) mixed with other fluoride salts. For instance, a UF4 based fuel salt may include a mixture of LiF, BeF2, ThF4 and UF4. It is noted that in such a family of UF4 based fuel salt compositions the heavy metal content may range from approximately 40-45% by weight and have a melting temperature of approximately 500° C. This disclosure describes specific embodiments of uranium salts of chloride usable as nuclear fuel in certain molten salt reactor designs. Where the parent application describes a wide range of binary, ternary and quaternary chloride fuel salts of uranium, as well as other related technologies, this disclosure focuses on fuel salt embodiments determined to be particularly suited for certain reactor designs. Due to the high level of fissile content achievable through molten fuel salts of the present disclosure and the ease of access to the molten fuel salt, it is desirable to provide non-proliferation measures with respect to the fuel(s) of the present disclosure. Some embodiments of the present disclosure provide a molten fuel salt that is pre-loaded (i.e., loaded prior to start-up) with one or more selected lanthanides to increase the activity of the initial salt. In addition, unless subsequently separated, the lanthanides will act as a neutron poison in the fuel and, thus, reduce the desirability of the lanthanide-loaded fuel for weapons-grade purposes. In one aspect, the fuel salts of this disclosure include ternary fuel salts of UCl3, UCl4, and NaCl having a melting point of less than 600° C., from 1 to 50 mol % UCl4, a uranium density of greater than 1.5 g/cc, and a specific heat of greater than 600 J/kg-C. Embodiments of fuel salts may have melting points of less than 600° C., 550° C., 500° C., 450° C., 400° C., or even 350° C. Embodiments of fuel salts may have a uranium density of greater than 1.5 g/cc, 1.6 g/cc, 1.7 g/cc, 1.8 g/cc, 1.9 g/cc, 2 g/cc or even 2.1 g/cc. Embodiments of fuel salts may have a specific heat of greater than 600 J/kg-C, 700 J/kg-C, 800 J/kg-C, or even 900 J/kg-C. Embodiments of fuel salts may also have reduced amounts of UCl4 (relative to 17UCl3-71UCl4-12NaCl). In addition to the properties described above, such embodiments of fuel salts may have less than 50 mol % UCl4, less than 40%, 30%, 20%, 15% or even less than 10 mol % UCl4. Embodiments of uranium fuel salts have a molar fraction of UCl4 from 1% to 50% by molar fraction UCl4. Embodiments of fuel salts have a molar fraction of UCl3 from 1% to 33% by molar fraction UCl3. Embodiments of fuel salts have a molar fraction of NaCl wherein the fissionable fuel salt has from 40% to 66% by molar fraction NaCl. These and various other features as well as advantages which characterize the systems and methods described herein will be apparent from a reading of the following detailed description and a review of the associated drawings. Additional features are set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the technology. The benefits and features of the technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are explanatory and are intended to provide further explanation of the invention as claimed. This disclosure describes embodiments of nuclear fuel salts usable in certain molten salt reactor designs and related systems and methods. Binary, ternary and quaternary chloride fuel salts of uranium, as well as other fissionable elements, are described. In addition, fuel salts of UClxFy are disclosed as well as bromide fuel salts. This disclosure also presents methods and systems for manufacturing such fuel salts, for creating salts that reduce corrosion of the reactor components and for creating fuel salts that are not suitable for weapons applications. The present disclosure is directed to a fast spectrum molten salt breed-and-burn nuclear reactor fuel and methods of fuel fabrication, management and use. Much of the historical and current research related to molten salt nuclear fission reactors focused on uranium- and thorium-based fluorine salts. The molten chlorides differ significantly from the fluoride based salts due to a couple of key aspects. First, chlorides can be somewhat less moderating than the fluorides, particularly if the chlorides are enriched with the 37Cl isotope. Second, the chlorides offer the possibility of very high heavy metal concentrations in mixtures with reasonable melting points. This is an aspect which allows for the utilization of the uranium chlorine salt mixtures in a fast neutron spectrum. Fluoride salts typically contain no more than 10-12 mol % heavy metal. Historically proposed fluorine salt mixtures typically contained molar concentrations of 63-72 mol % LiF (enriched to 99.997%7Li), 16-25 mol % BeF2, 6.7-11.7 mol % ThF4, and only 0.3 mol % UF4 (heavy metal is 40-45%, by weight). Such salts melted at 500° C. By contrast, one embodiment of a chloride salt proposed here has a composition of 17UCl3-71UCl4-12NaCl (62%, by weight, heavy metal), and it also melts at 500° C., as discussed in greater detail below. Some fuel embodiments of the present disclosure may provide for equilibrium or quasi-equilibrium breed-and-burn behavior, while other embodiments provide for non-equilibrium breed-and-burn behavior without reprocessing of the fuel salt. This is notable because prior molten salt reactor designs could not achieve equilibrium breed-and-burn behavior without chemical separation of the fuel salt in the reactor necessitating ongoing chemical reprocessing of the fuel salt. For example, the present disclosure discloses, but is not limited to, a molten chloride fuel salts suitable for use in a fast spectrum reactor displaying equilibrium, quasi-equilibrium and/or non-equilibrium breed-and-burn behavior. In embodiments, little or no reprocessing may be required and what little reprocessing that may be used may be physical reprocessing only (e.g., physical separation of byproducts such as by gas sparging and/or filtering). Various embodiments of the molten fuel salt of the present disclosure may include mixtures of a first uranium chloride salt, a second uranium chloride salt and/or additional metal chloride salts. Some embodiments of the present disclosure provide for a molten fuel salt having a uranium tetrachloride (UCl4) content level above 5% by molar fraction, which aids in establishing a high heavy metal content in the molten fuel salt (e.g., above 61% by weight) while maintaining operable melting temperatures. Embodiments including UCl4 may be formed through a mixture of UCl4 and uranium trichloride (UCl3) and/or and additional metal chloride (e.g., NaCl) such that desirable heavy metal content levels and melting temperatures (e.g., 330-800° C.) are achieved. Due to the high level of fissile content achievable through molten fuel salts of the present disclosure and the ease of access to the molten fuel salt, it is desirable to provide non-proliferation measures with respect to the fuel(s) of the present disclosure. Some embodiments of the present disclosure provide a molten fuel salt that is pre-loaded (i.e., loaded prior to start-up) with one or more selected lanthanides to increase the activity of the initial salt. In addition, unless subsequently separated, the lanthanides will act as a neutron poison in the fuel and, thus, reduce the desirability of the lanthanide-loaded fuel for weapons-grade purposes. Molten Salt Reactors Prior to discussing the fuel salt embodiments in greater detail, a brief discussion of the general components of molten fuel salt reactors suitable for using the fuel salt embodiments will be helpful. FIGS. 1A-1F generally describe a novel embodiment of a molten salt nuclear reactor 100 for operating in a fast spectrum breed-and-burn mode. FIG. 2 describes a different configuration of a molten salt nuclear reactor 200. These are just examples to provide context for discussion of the fuel embodiments described herein and the reader should understand that potentially any molten fuel nuclear reactor could be adapted to use the fuel embodiments described below. While various fluoride salts may be utilized in molten salt nuclear reactors as described below, fluoride-based fuel salts typically display heavy metal concentrations significantly below that which may be achieved with chloride-based and chloride-fluoride-based fuel salts described in the present disclosure. FIG. 1A illustrates a simplified schematic view of a molten salt fast spectrum nuclear reactor 100, in accordance with one or more embodiments of the present disclosure. In one embodiment, the reactor 100 includes a reactor core section 102. The reactor core section 102 (which may also be referred to as the “reactor vessel”) includes a fuel input 104 and a fuel output 106. The fuel input 104 and the fuel output 106 are arranged such that during operation a flow of the molten fuel salt 108 is established through the reactor core section 102. For example, the fuel input 104 and/or the fuel output 106 may consist of conical sections acting as converging and diverging nozzles respectively. In this regard, the molten fuel 108 is fluidically transported through the volume of the reactor core section 102 from the input 104 to the output 106 of the reactor core section 102. Although FIG. 1A shows fluid fuel flow with arrows, it is to be appreciated that the direction of flow may be modified as appropriate for different reactor and plant configurations. Specifically, FIG. 1A shows fluid fuel 108 flow from the ‘bottom’ to the ‘top’ in the central core region, and alternative apparatuses may create and/or maintain a fluid fuel 108 flow from the top towards the bottom in the central core region. The reactor core section 108 may take on any shape suitable for establishing criticality within the molten fuel salt 108 within the reactor core section 102. By way of non-limiting example, the reactor 100 may include, but is not limited to, an elongated core section, as depicted in FIG. 1A. In addition, the reactor core section 108 may take on any cross-sectional shape. By way of non-limiting example, the reactor core section 108 may have, but is not required to have, a circular cross-section, an ellipsoidal cross-section or a polygonal cross-section. The dimensions of the reactor core section 102 are selected such that criticality is achieved within the molten fuel salt 108 when flowing through the reactor core section 102. Criticality refers to a state of operation in which the nuclear fuel sustains a fission chain reaction, i.e., the rate of production of neutrons in the fuel is at least equal to rate at which neutrons are consumed (or lost). For example, in the case of an elongated core section, the length and cross-sectional area of the elongated core section may be selected in order to establish criticality within the reactor core section 102. It is noted that the specific dimensions necessary to establish criticality are at least a function of the type of fissile material, fertile material and/or carrier salt contained within the reactor 100. Principles of molten fuel nuclear reactors are described in U.S. patent application Ser. No. 12/118,118 to Leblanc, filed on May 9, 2008, which is incorporated herein in the entirety. The reactor core section 102 is formed from any material suitable for use in molten salt nuclear reactors. For example, the bulk portion of the reactor core section 102 may be formed, but is not required to be formed, from one or more molybdenum alloy, one or more zirconium alloys (e.g., ZIRCALOY™), one or more niobium alloys, nickel, one or more nickel alloys (e.g., HASTELLOY™ N) or high temperature ferritic, martensitic, or stainless steel and the like. It is further noted that the internal surface may coated, plated or lined with one or more additional materials in order to provide resistance to corrosion and/or radiation damage, as discussed in additional detail further herein. In the embodiment shown, the reactor 100 includes a primary coolant system 110 that takes heat from the reactor core 102 and transfers that heat to the secondary coolant 126 in the secondary coolant system 120 via the heat exchanger 119. In the embodiment illustrated in FIG. 1A, the molten fuel salt 108 is used as the primary coolant 118. Cooling is achieved by flowing molten fuel salt 108 heated by the ongoing chain reaction from the reactor core 102, and flowing cooler molten fuel salt 108 into the reactor core 102, at the rate necessary to maintain the temperature of the reactor core 102 within its operational range. In this embodiment, the primary coolant system 110 is adapted to maintain the molten fuel salt 108 in a subcritical condition when outside of the reactor core 102. The primary coolant system 110 may include one or more primary coolant loops 112 formed from piping 114. The primary coolant system 110 may include any primary coolant system arrangement known in the art suitable for implementation in a molten fuel salt context. The primary coolant system 110 may circulate fuel 108 through one or more pipes 114 and/or fluid transfer assemblies of the one or more primary coolant loops 112 in order to transfer heat generated by the reactor core section 102 to downstream thermally driven electrical generation devices and systems. For purposes of simplicity, a single primary coolant loop 112 is depicted in FIG. 1A. It is recognized herein, however, that the primary coolant system 110 may include multiple parallel primary coolant loops (e.g., 2-5 parallel loops), each carrying a selected portion of the molten fuel salt inventory through the primary coolant circuit. In an alternative embodiment (an example of which is shown in FIGS. 1G and 2), the primary coolant system 110 may be configured such that a primary coolant 118 (different than the molten fuel salt 108) enters the reactor core section 108 (e.g., main vessel). In this embodiment, the fuel salt 108 does not leave the reactor core section, or main vessel, but rather the primary coolant 118 is flowed into the reactor core 102 to maintain the temperature of the core within the desired range. It is noted that in this embodiment the reactor 100 may include an additional heat exchanger (not shown) in the reactor core section 102, or main vessel. In this embodiment, the secondary coolant system 120 may be optional, the usable thermal power can be derived directly from the primary coolant system 110. In this embodiment, the primary coolant may be a chloride salt with a suitable melting point. For example, the salt may be a mixture of sodium chloride and magnesium chloride. In the embodiment shown in FIG. 1A, the primary coolant system 110 includes one or more pumps 116. For example, one or more pumps 116 may be fluidically coupled to the primary coolant system 110 such that the one or more pumps 116 drive the primary coolant 118, in this case the molten fuel 108, through the primary coolant/reactor core section circuit. The one or more pumps 116 may include any coolant/fuel pump known in the art. For example, the one or more fluid pumps 116 may include, but are not limited to, one or more mechanical pumps fluidically coupled to the primary coolant loop 112. By way of another example, the one or more fluid pumps 116 may include, but are not limited to, one or more electromagnetic (EM) pumps fluidically coupled to the primary coolant loop 112. FIG. 1A further illustrates that the reactor 100 includes a secondary coolant system 120 thermally coupled to the primary coolant system 110 via one or more heat exchangers 119. The secondary coolant system 120 may include one or more secondary coolant loops 122 formed from piping 124. The secondary coolant system 120 may include any secondary coolant system arrangement known in the art suitable for implementation in a molten fuel salt context. The secondary coolant system 120 may circulate a secondary coolant 126 through one or more pipes 124 and/or fluid transfer assemblies of the one or more secondary coolant loops 122 in order to transfer heat generated by the reactor core section 102 and received via the primary heat exchanger 119 to downstream thermally driven electrical generation devices and systems. For purposes of simplicity, a single secondary coolant loop 124 is depicted in FIG. 1A. It is recognized herein, however, that the secondary coolant system 120 may include multiple parallel secondary coolant loops (e.g., 2-5 parallel loops), each carrying a selected portion of the secondary coolant through the secondary coolant circuit. It is noted that the secondary coolant may include any second coolant known in the art. By way of example, the secondary coolant may include, but is not limited to, liquid sodium. It is further noted that, while not depicted in FIG. 1A, the reactor 100 may include any number of additional or intermediate heating/cooling systems and/or heat transfer circuits. Such additional heating/cooling systems may be provided for various purposes in addition to maintaining the reactor core 102 within its operational temperature range. For example, a tertiary heating system may be provided for the reactor core 102 and primary coolant system 110 to allow a cold reactor containing solidified fuel salt to be heated to an operational temperature in which the salt is molten and flowable. Other ancillary components 127 may also be utilized, as illustrated, in the primary coolant loop 112. Such ancillary components 127 may be include one or more filters or drop out boxes for removing particulates that precipitate from the primary coolant 118 during operation. To remove unwanted liquids from the primary coolant 118, the ancillary components 127 may include any suitable liquid-liquid extraction system such as one or more co-current or countercurrent mixer/settler stages, an ion exchange technology, or a gas absorption system. For gas removal, the ancillary components 127 may include any suitable gas-liquid extraction technology such as a flash vaporization chamber, distillation system, or a gas stripper. Some additional embodiments of ancillary components 127 are discussed in greater detail below. It is noted herein that the utilization of various metal salts, such as metal chloride salts, in reactor 100 may cause corrosion and/or radiation degradation over time. A variety of measures may be taken in order to mitigate the impact of corrosion and/or radiation degradation on the integrity of the various salt-facing components (e.g., reactor core section 102, primary coolant piping 114, heat exchanger 119 and the like) of the reactor 100 that come into direct or indirect contact with the fuel salt or its radiation. In one embodiment, the velocity of fuel flow through one or more components of the reactor 100 is limited to a selected fuel salt velocity. For example, the one or more pumps 116 may drive the molten fuel 108 through the primary coolant loop 112 of the reactor 100 at a selected fuel salt velocity. It is noted that in some instances a flow velocity below a certain level may have a detrimental impact on reactor performance, including the breeding process and reactor control. By way of non-limiting example, the total fuel salt inventory in the primary loop 112 (and other portions of the primary coolant system 110) may exceed desirable levels in the case of lower velocity limits since the cross-sectional area of the corresponding piping of the primary loop 112 scales upward as flow velocity is reduced in order to maintain adequate volumetric flow through the primary loop 112. As such, very low velocity limits (e.g., 1 m/s) result in large out-of-core volumes of fuel salt and can negatively impact the breeding process of the reactor 100 and reactor control. In addition, a flow velocity above a certain level may detrimentally impact reactor performance and longevity due to erosion and/or corrosion of the internal surfaces of the primary loop 112 and/or reactor core section 102. As such, suitable operational fuel salt velocities may provide a balance between velocity limits required to minimize erosion/corrosion and velocity limits required to manage out-of-core fuel salt inventory. For example, in the case of a molten chloride fuel salt, the fuel salt velocity may be controlled from 2-20 m/s, such as, but not limited to, 7 m/s. FIGS. 1B and 1C illustrate a simplified schematic view of a molten salt fast spectrum nuclear reactor 100 with a protective layer 128 disposed on one or more internal surfaces of the reactor 100, in accordance with one or more embodiments of the present disclosure. In one embodiment, the protective layer 128 is disposed on one or more surfaces of the reactor 100 facing the fuel salt 108 of the reactor 100. The protective layer 128 may provide resistance to corrosion and/or radiation degradation of one or more reactor salt-facing surfaces of the reactor 100. For the purposes of the present disclosure, a material resistant to corrosion and/or radiation degradation is interpreted as any material displaying resistance to corrosion and/or radiation degradation superior to the underlying bare surface of the reactor 100. The protective layer 128 may include any material known in the art suitable for providing an internal surface of a reactor with corrosion and/or radiation resistance to a corresponding nuclear fuel salt. Thus, the material of the protective layer 128 may vary depending on the salt 108 used. In one embodiment, the protective layer 128 includes one or more refractory metals. For example, the protective layer 128 may include, but is not limited to, one or more of niobium, molybdenum, tantalum, tungsten or rhenium. In another embodiment, the protective layer 128 includes one or more refractory alloys. For example, the protective layer 128 may include, but is not limited to, one or more of a molybdenum alloy (e.g., titanium-zirconium-molybdenum (TZM) alloy), a tungsten alloy, tantalum, a niobium or a rhenium. In another embodiment, the protective layer 128 includes nickel and/or one or more nickel alloys. In another embodiment, the protective layer 128 includes a carbide, such as, but not limited to, silicon carbide. In an embodiment, the protective layer 128 is formed by plating the internal surface of the one or more portions (e.g., piping 114 or primary loop 112) of the reactor 100 with the selected protective material. In another embodiment, the protective layer 128 includes one or more coatings of the selected protective material disposed on the internal surface of one or more portions of the reactor 100. In yet another embodiment, the bulk material of the various components may be formed with one or more of the protective materials described above. For instance, the piping 114 of the primary coolant loop 112 may include, but is not limited to, TZM piping. In one embodiment, as shown in FIG. 1B, the internal salt-facing surface of the reactor core section 102 includes a protective layer 128. For example, the vessel of the reactor core section 102 may be formed from steel or a zirconium alloy, with refractory alloy, nickel, or nickel alloy plating disposed on the internal salt-facing surface of the reactor core section 102 to form the protective layer 128. For instance, the reactor core section 102 may include, but is not limited to, a molybdenum-based protective layer 128 having a thickness from approximately 5-7 mm, with the vessel of the reactor core section 102 having a wall thickness of approximately 9-11 cm thick. Similarly, as shown in FIG. 1C, the salt-facing surface of the piping 114 of the primary coolant loop 112 (which may be the internal and/or external surface of piping or other components) includes a protective layer 128. For example, refractory alloy or nickel alloy plating may be disposed on the salt-facing surface of the piping 114 of the primary coolant loop 112 to form the protective layer 128. FIG. 1D illustrates a schematic view of a reflector assembly 130 of the reactor core 100. The reflector assembly 130 is suitable for reflecting neutrons emanating from the reactor core section 102 back into the fuel salt 108. In one embodiment, the reflector assembly 130 is disposed at the external surface of the reactor core section 102 such that the reflector assembly 130 surrounds at least a portion of the reactor core 102. In the embodiment shown, the neutrons reflected back into the reactor core section 102 by the reactor assembly 130 may contribute to maintaining criticality within the reactor core section 102 and/or the breeding of fissile fuels from fertile feed materials. By reducing such losses of neutrons, the amount of fuel salt necessary for criticality, therefore, the size of the reactor core 102, may be reduced. The reflector assembly 130 may be formed from any material known in the art suitable for neutron reflection. For example, the reflector assembly may include, but is not limited to, one or more of zirconium, steel, iron, graphite, beryllium, tungsten carbide, lead, lead-bismuth and like materials. FIGS. 1E and 1F illustrate the reflector assembly 130 constructed with multiple reflector modules 132, in accordance with one or more embodiments of the present disclosure. It is noted that at some operating temperatures of the nuclear reactor 100 of the present disclosure a variety of neutron reflecting materials will liquefy. For example, lead and lead-bismuth are both materials that provide good neutron reflecting characteristics. However, lead melts at approximately 327° C., while lead-bismuth alloys commonly have melting temperatures below 200° C. As noted elsewhere in this application, the reactor 100 may operate in a temperature range from approximately 330 to 800° C., above the melting points associated with lead and lead-bismuth alloys. In one embodiment, the reactor modules 132 include a reflector container to contain a liquid-phase of the selected neutron reflecting material 133, as shown in FIGS. 1E and 1F. The reactor modules 132 may be formed from any material known in the art and may be selected based on consideration of any one or more design functions including temperature resistance, corrosion resistance, non-reactivity with other components and/or the fuel, radiation resistance, structural support, weight, etc. In some cases, one or more reflector containers may be formed of a material which is substantially neutronically translucent with the reflector material inside the container, and/or one or more reflector containers may be formed of a material which is refractory. For example, the reflector modules 132 (such as the reflector containers) may be formed from one or more refractory alloys, one or more nickel alloys or one or more carbides, or graphite compounds. For instance, the material used to form the reflector modules 132 and/or reflector containers may include, but are not limited to, any one or more components or combinations of one or more molybdenum alloys (e.g., TZM alloy), one or more tungsten alloys, one or more tantalum alloys, one or more niobium alloys, one or more rhenium alloys, one or more nickel alloys, silicon carbide, or graphite compounds, and the like. The reflector module may include (either contain or be formed from) one or more moderating compounds that can exist at the operating temperatures (e.g., graphite and/or lead) and may consider balancing a stronger moderator (e.g., graphite) and a weaker moderating material (e.g., lead) and may be used to determine the overall reflector neutron spectrum. In one embodiment, the reflector modules 132 are positioned at the external surface of the reactor core section 102 and distributed across the external surface of the reactor core section 102. As shown in the examples of FIGS. 1E and 1F, the reflector modules 132 are arranged azimuthally across the external surface of the reactor core section 102. Each reflector module 132 contains a volume of neutron reflecting liquid (e.g., lead, lead-bismuth or the like). In this regard, the discrete reflector modules 132 may be arranged to form a contiguous volume of neutron reflecting liquid 133 the reactor core section 102. While FIGS. 1E and 1F depict an azimuthal arrangement of reflector modules 132, such a configuration should not be interpreted as limiting. It is noted herein that any geometrical arrangement and number of reflector modules 132 is suitable for implementation within the context of reactor 100 of the present disclosure. For example, although not shown, the set of reflector modules 132 may take on a stacked-ring configuration, with each module being a ring filled with the selected neutron reflecting liquid. In this regard, set of modules 132 may be stacked so as to form a neutron reflecting volume about the core section 102. The volume may be spherically shaped, cylindrically shaped, may be a rectangular-, hexagonal-, octagonal-, triangular-, pentagonal-, or other prism or otherwise be a volume of any cross-sectional shape. In an embodiment, the reflector will utilize a 12.7-mm-thick (½″-thick) HASTELLOY™-N or SiC plating on all exterior surfaces and the inner vessel will have a thickness of 2 cm of the same plating material. It is to be appreciated that the shape of the reflector modules may be formed as appropriate for the core design and may include any appropriate shape including trapezoidal rectangular, hexagonal, circular, ellipsoidal, and may even include irregular shapes. FIG. 1G illustrates an embodiment of a nuclear power plant for generating power from a nuclear reaction using a molten chloride fast reactor (MCFR). For a power plant application, the heat generated by the MCFR will be converted into electrical power by power conversion hardware. In the embodiment shown, Rankine cycle power conversion hardware was used with water (steam) as the working fluid. The conversion efficiency of a Rankine cycle plant is in large part determined by the temperature (and pressure) of the steam entering the turbines, where higher temperatures correlate to higher efficiency. Performance is coupled to steam pressure as well as temperature and the highest efficiency Rankine cycle plants use supercritical and ultra-supercritical steam. The power conversion system encompasses all systems that come into contact with the power conversion system working fluid. In the case of a steam Rankine cycle plant as illustrated, this includes a steam generator 152, a turbine system 154, water circulation loop 162 including one or more water circulation pumps 156 and a cooling tower 158, electrical generation equipment 160 and a control system 162. In addition, a fuel storage system 166 for storing new fuel salt and a reaction product storage system 168 to receive and safely contain used fuel salt are illustrated. As illustrated in FIG. 1G, the power conversion system starts with a primary coolant transferring heat to the power cycle working fluid through a heat exchanger (e.g. steam generator 152). A modelling of the system included simplified models of the primary coolant salt loop 114, and steam generator 152, with more detailed treatment of the Rankine cycle system components. Although a Rankine cycle steam turbine was used for modelling purposes, heat engines based on other cycles are also feasible such as closed-cycle gas turbines (e.g., air, helium, or CO2) based on the Brayton cycle. Inputs to the power conversion system used in the modelling come from primary coolant heat transfer fluid mass flow rate, supply and return temperatures and pressures. The power cycle cost and performance are evaluated for different rated thermal power output levels of 600 MW, 1200 MW, 1800 MW, 2400 MW, and 3000 MW. For the baseline reactor design conditions, the primary coolant salt temperature is delivered to the steam generator 152 at 612° C. and is returned from the steam generator 152 at 498° C. The analysis included modelling operation with 580° C., 300 bar main steam conditions and 600° C., 70 bar reheat steam conditions, although higher and lower temperature and pressure operation may affect cost and performance. The analysis used Themoflow, Inc.'s software packages STEAMPRO™ and THERMOFLEX™ to provide cost and performance data for the power cycle for steady state operation. The analysis used standard thermodynamic models for turbine system 154 components, coupled with proprietary models for specific components in the power cycle. A large body of water, like a river or lake, is assumed to be available for heat rejection (i.e. no cooling towers were modeled), although a cooling tower 158 could be utilized as illustrated in FIG. 1G for heat rejection. Thermodynamic efficiencies and component parameters are kept at the default values determined by STEAMPRO™ and THERMOFLEX™ submodels. For the modelling, a fuel salt of 17% UCl3-71% UCl4-12% NaCl and primary coolant of 58% NaCl-42% MgCl2 were used. Fuel salt properties have been added to THERMOFLEX™ as lookup tables based on data curve fits. The data used are shown in Table 1 for fuel salt and Table 2 for primary coolant salt, below. TABLE 1Fuel salt properties used in THERMOFLEX ™ calculations Specific Thermal Dynamic Vapor Temperature Density Heat Cond. Visc. Pressure ° C. kg/m3 kJ/kg-C W/m-C kg/m-s bar1 400 4189 0.5732 0.972 0.0171 0 2 450 4077 0.5515 1.081 0.0117 0 3 500 3965 0.5297 1.19 0.00817 0 4 550 3853 0.5079 1.299 0.00585 0 5 600 3741 0.4861 1.409 0.00427 0 6 650 3629 0.4644 1.518 0.00317 0 7 700 3517 0.4426 1.627 0.00239 0 8 750 3406 0.4208 1.736 0.00183 0 9 800 3294 0.399 1.845 0.00142 0 10 850 3182 0.3773 1.954 0.00111 0 11 900 3070 0.3555 2.064 8.83E−04 0 12 950 2958.3 0.3337 2.173 7.07E−04 0 13 1000 2846.5 0.3119 2.282 5.71E−04 0 14 1050 2734.6 0.2902 2.391 4.65E−04 0 15 1100 2622.8 0.2684 2.5 3.81E−04 0 16 1150 2511 0.2466 2.609 3.15E−04 0 17 1200 2399.1 0.2248 2.719 2.62E−04 0 18 1250 2287.3 0.2031 2.828 2.19E−04 0 19 1300 2175.5 0.1813 2.937 1.85E−04 0 20 1350 2063.6 0.1595 3.046 1.56E−04 0 21 1400 1951.8 0.1377 3.155 1.33E−04 0 22 1450 1840 0.116 3.264 1.14E−04 0 23 1500 1728.1 0.0942 3.374 9.74E−05 0 24 1550 1616.3 0.0724 3.483 8.40E−05 0 25 1600 1504.5 0.0506 3.592 7.27E−05 0 26 1650 1392.6 0.0289 3.701 6.32E−05 0 27 1700 1280.8 0.00709 3.81 5.51E−05 0 TABLE 2Primary coolant salt properties used in THERMOFLEX ™ calculations Specific Thermal Dynamic Vapor Temperature Density Heat Cond. Visc. Pressure ° C. kg/m3 kJ/kg-C W/m-C kg/m-s bar1 444.8 1785 1.128 1.555 0.0023 0 2 498.6 1759 1.114 1.672 0.00201 0 3 552.2 1734 1.1 1.789 0.00176 0 4 606 1708 1.086 1.906 0.00154 0 5 659.6 1683 1.072 2.022 0.00134 0 6 713.2 1658 1.058 2.139 0.00118 0 7 766.8 1632 1.044 2.255 0.00103 0 8 820.8 1607 1.03 2.372 8.98E−04 0 9 873.8 1581 1.016 2.487 7.87E−04 0 10 927.8 1556 1.002 2.604 6.87E−04 0 11 981.8 1530 0.9874 2.721 6.01E−04 0 12 1035.8 1505 0.9732 2.838 5.25E−04 0 13 1088.8 1479 0.9593 2.952 4.60E−04 0 14 1142.8 1454 0.9452 3.069 4.02E−04 0 15 1196.8 1428 0.931 3.186 3.51E−04 0 16 1249.8 1403 0.9171 3.3 3.07E−04 0 17 1303.8 1378 0.9029 3.416 2.69E−04 0 18 1357.8 1352 0.8887 3.532 2.35E−04 0 19 1410.8 1327 0.8748 3.647 2.06E−04 0 20 1464.8 1301 0.8607 3.763 1.80E−04 0 The power conversion system receives thermal power from the reactor 100 and converts that heat into mechanical and then electrical power. The analysis specifically focused on using conventional steam Rankine cycle hardware for power conversion. The analyzed configuration has three-turbines, with a high pressure turbine (HPT), intermediate pressure turbine (IPT), and low pressure turbine (LPT), illustrated simply as the turbine system 154. FIG. 1G shows a simplified cycle diagram for the 2400 MWth Rankine cycle analysis. The model in FIG. 1G is simplified in that it shows only the major components of the power plant. In the model used, the HPT receives steam from the “main steam” generation system that is heated by the primary cooling fluid carrying thermal energy from the reactor. Exhaust from HPT is sent to the reheat steam generation system, where the primary cooling fluid transfers heat to the exhaust from the HPT, and that heated steam is fed to the IPT. The exhaust from the IPT is fed to directly to the LPT to extract additional enthalpy. There are often multiple turbines in parallel, particularly for the LPT. In the model used, there are twin LPTs that are used for the final expansion step. In the model, all turbines are on a common shaft and direct coupled to an electrical generator 160. The outlet of the LPT flows to a condenser that cools the steam to near ambient temperature. For this analysis, the LPT is assumed to be a once-through condenser that receives heat from a large body of water, like a large lake or river. After the condenser, the water is pumped and sent through several feedwater heaters. The feedwater heaters preheat the feedwater by mixing with steam extracted from various points on the turbines. The preheated fluid from the feedwater heaters is then fed to the steam generator, where it is heated to temperature for the main turbine. The analysis process involves using STEAMPRO™ to specify the characteristics of the Rankine cycle system, and then exporting that model to Thermoflex to investigate the interactions with the molten salt loops. STEAMPRO™ is a purpose-built tool for configuring steam turbine components, while Thermoflex is considered a “fully-flexible” design tool with more features and options. In STEAMPRO™, the plant is defined as having a “black-box steam generator” and “once-through open-loop water cooling.” The steam cycle is defined as single-reheat condensing supercritical cycle with an electric motor driven boiler feed pump. All turbines are specified to operate at 3600 RPM. The turbine group characteristics, feedwater heaters, and pumps are determined by STEAMPRO™'s default parameters and selection method. The cycle is then computed and exported to THERMOFLEX™. STEAMPRO™ gives a detailed component layout of the Rankine cycle plant selected for efficient operation at rated conditions. In THERMOFLEX™, the black-box steam generator is replaced with molten-salt-to-steam heat exchangers for the main and reheat steam generators. Simplified fuel salt and primary coolant salt loops are included in the model. The fuel and primary coolant salt loops are included to provide the energy source and are not modeled in detail. The modelling approach in THERMOFLEX™ is to specify outlet conditions of heat exchangers in the salt and steam loops, and then adjust the steam flow rate to that the heat input into the fuel salt matches the rated conditions. Although the component layout and performance characteristics of the plant was determined by STEAMPRO™, THERMOFLEX™ will further tune (resize) components (e.g. turbines, pumps, and heat exchangers) to achieve good performance for the working fluid conditions. The heat input into the fuel salt loop represents the thermal power of the reactor. The gross efficiency is the turbine shaft power output relative to the thermal power input. Net power is generator output power subtracting pumping and auxiliary losses relative to thermal power input. Table 3 below shows the performance and cost results for the supercritical Rankine cycle operated with thermal power input of 600 MW, 1200 MW, 1800 MW, 2400 MW, and 3000 MW. TABLE 3Performance and overall THERMOFLEX ™ cost results for supercritical Rankine operation at thermal power levels from 600 MW to 3000 MWHeat input MW 600.0 1200.0 1800.0 2400.0 3000.1 Net power MW 276.1 560.9 845.5 1130.3 1415.2 Net electrical % 46.0 46.7 47.0 47.1 47.2 efficiency Fuel salt mass flow kg/s 14625 29251 43876 58501 73130 Primary coolant salt kg/s 4774 9487 14231 18975 23719 total mass flow Primary coolant salt kg/s 3800 7520 11244 14968 18691 mainsteam generator mass flow Primary coolant salt kg/s 943.7 1967 2986.4 4006 5029 reheater mass flow Main steam mass flow kg/s 224.5 452.8 677.1 901.3 1025 rate Reheat steam mass kg/s 195.2 403.7 610.9 818 1125.4 flow rate Fuel salt heat source ° C. 737 737 737 737 737 outlet Fuel salt primary heat ° C. 645 645 645 645 645 exchanger outlet Primary coolant ° C. 612 612 612 612 612 primary heat exchanger outlet Primary coolant main ° C. 498 498 498 498 498 steam generator outlet Primary coolant reheat ° C. 498 498 498 498 498 steam generator outlet Main steam generator ° C. 580 580 580 580 580 steam outlet Reheat steam ° C. 600 600 600 600 600 generator outlet FIG. 2 illustrates another embodiment of a simplified schematic view of a molten salt nuclear reactor 200. The reactor 200 is a pool-type reactor in which in some examples the fuel salt 108 may be flowing/circulating through the pool or in other cases contained or guided such as through piping. In the example shown in FIG. 2, the fuel salt is contained in tubes 204 that are located at the center of a pool 210 of coolant 202 in a closed reactor vessel 206. The top portion of the reactor vessel 206 may be filled with some inert gas 218 such as argon. The fuel tubes 204 are arranged in an array similar to conventional solid fuel arrays in a light water reactor. The coolant 202 transfers heat from the center of the pool 210 to heat exchangers 208 located on the periphery of the pool 210. In the embodiment shown, the circulation of the coolant 202 (illustrated by the dashed arrows 212) within the pool 210, which may be natural or induced by an impeller or other mechanism (not shown), convects heat away from the fuel tubes 204 to be removed by the heat exchangers 208. The heat exchangers 208 transfer heat from the pool 210 to a secondary coolant system 214. In an embodiment, the secondary coolant is water that is boiled in the heat exchangers and the resulting steam 216 is used to drive turbines (not shown) for the generation of power. An optional set of reflector modules 232, such as reflector modules 132 discussed with reference to FIGS. 1E and 1F, may be provided around the array of fuel tubes either within the reactor vessel as shown in FIG. 2 and/or external to the reactor vessel similar to that of FIGS. 1E and 1F to increase the efficiency of the reactor. Optional shutdown rods may be provided to maintain the reactor subcritical when needed. Following its initial start-up with enriched (˜12% 235U) fuel, an MCFR may not require the ongoing feed of enriched fissile material. Instead, an MCFR can be fed depleted or natural uranium, among other fertile materials. During normal operations, modelling shows that the reactor slowly breeds up in reactivity. To counter this increase in reactivity, a small quantity of fully mixed fuel salt may be removed and replaced with fertile feed salt. The addition of fertile material is, in effect, a control rod that reduces reactivity. Rather than going to disposal, used MCFR fuel can be collected until a sufficient amount is available to start a new reactor. Such a daughter reactor contains a chemically identical fuel salt, and thus, is able to be started without any new enrichment. By transferring used fuel, in total, to a daughter plant for use as the initial fuel for that plant, creation of a fleet of MCFRs significantly reduces the use of actinides and defers the vast majority of radioactive waste until the end of fleet build-out. For ultimate disposal of actinide-bearing fuel salt, prior work found that the salt itself could be packaged, without chemical conversion, into a suitable waste form. Chloride-Based Fuel Salts Nuclear fuel salts are generally described by E. H. Ottewitte, “Configuration of a Molten Chloride Fast Reactor on a Thorium Fuel Cycle to Current Nuclear Fuel Cycle Concerns,” Ph.D. dissertation, University of California at Los Angeles, 1982, which is incorporated herein by reference in the entirety. Uranium chloride compounds are also discussed generally by B. R. Harder, G. Long and W. P. Stanaway, “Compatibility and Processing Problems in the Use of Molten Uranium Chloride-Alkali Chloride Mixtures as Reactor Fuels,” Symposium on Reprocessing of Nuclear Fuels, Iowa State University, 405-432, August 1969, which is incorporated herein by reference in the entirety. The novel fuel salt embodiments described below improve this work and have been developed through modelling and other theoretical research. It is noted that the molten chloride fuel salts of the present disclosure provide for the introduction of high heavy metal concentration in the fuel salt 108 at reasonable temperatures. By way of a non-limiting example, one or more of the chloride fuel salts of the present disclosure may provide a heavy metal concentration of greater than 61% by weight, with a melting temperature of approximately 500° C. When operated using the fuel salts described below, embodiments of a molten fuel salt reactor may have possible nominal operating temperatures from 200-800° C. While each different fuel will have a slightly different optimal operating temperature, reactors having an operational temperature range of 330-550° C., 350-520° C., 400-510° C. and 450-500° C. The ability to achieve high uranium content levels allows for the utilization of uranium chloride based fuel salt mixtures in the fast neutron spectrum breed-and-burn reactor of the present disclosure. Furthermore, the fissile material may be enriched to any level desired such as 12.5% 235U or 19.99% 235U, or any other suitable enrichment level. It is also noted that the molten chloride fuel salts of the present disclosure have a relatively low vapor pressure when heated to the operating temperatures described herein. While each different fuel will have a slightly different optimal operating pressure to reduce the amount of vaporization of the fuel salt, reactors having an operational pressure range of from 1-10 atm and from 2-5 atm are contemplated. The following discussion presents various embodiments of molten chloride nuclear fuel salt having a mixture of a metal chloride fuel salt with one or more additional metal chloride salts. For example, the molten chloride nuclear fuel salt may include, but is not limited to, a mixture of a first uranium chloride salt, a second uranium chloride salt and/or an additional metal chloride salt. It is noted that relative amounts of the various components of the fuel salt 108 may be manipulated to control one or more thermal, chemical or neutronic parameters of the fuel salt including, but not limited to, the melting point, thermal conductivity, corrosivity, actinide content level, reactivity, effective neutron multiplication factor (keff) at equilibrium, and the like. For example, the relative amount of fissile uranium (e.g. 235U) in a given fuel salt mixture may dictate the size of the reactor core section 102 necessary to provide a given power density. By way of non-limiting example, a fuel salt having a 235U content of 10 mol % (except where specifically stated otherwise, all % values for chemical compounds will be in molar %) may have a reactor core section volume of approximately 67 cubic meters (m3) and produce a power density of 200 MW/m3, while a fuel salt having a 235U content of 16% may only require a reactor core section volume of approximately 11 m3. Such a relationship shows the strong dependence of the size of the reactor core section 102 (or number of fuel tubes 204) on the composition of the utilized fuel salt 108. In one embodiment, the salt mixture of the present disclosure may be selected so that the associated breeding ratio, which is the ratio of the new fissile material created in a reactor during a nuclear reaction to the fissile material consumed by that reaction, of the fuel salt 108 is greater than 1 (e.g., breeding ratio=1.000001, 1.001, etc.), resulting in a long reactor life, but with a breeding performance less than potentially achievable. In another embodiment, the salt mixture of the present disclosure may be selected so that the associated breeding ratio of the fuel salt 108 is less than 1, resulting in burn off of enrichment for a given period of time. It is to be appreciated that selection of a specific fuel composition is dependent on many different competing factors including the reactor design, nominal operating parameters (e.g., temperature and pressure), and, not least of all, overall operational goals (e.g., reducing enrichment, reactor longevity, breeding additional fissile material). Chlorine-37 Modified Chloride Fuel Salt In addition to enriching the fissile element(s) (such as uranium or thorium) used to create the fuel salts, embodiments of the fuel salts described herein may be enriched so that some amount of the chloride ion in any one or more of the chloride compounds contain a specific percentage of 37Cl. Chlorine has many isotopes with various mass numbers. Of these, there are two stable isotopes, 35Cl (which forms 76% of naturally-occurring chlorine) and 37Cl (24% in naturally-occurring chlorine). The most common isotope, 35Cl, is a neutron moderator, that is, 35Cl reduces the speed of fast neutrons, thereby turning them into thermal neutrons. The isotope 35Cl is also a strong neutron absorber, and leads to formation of corrosive sulfur and long lived radioactive 36Cl. The isotope 37Cl, on the other hand, is relatively transparent to fast neutrons. One aspect of the present technology is to adjust the 37Cl content of any chloride-containing compounds to be used as molten fuel salt 108. As discussed above, use of naturally occurring chloride ions to create a chloride compound would result in roughly 76% of the chloride ions being 35Cl and 24% being 37Cl. However, in the embodiments described herein any ratio of 37Cl to total Cl may be used in any particular chloride fuel salt embodiment, and in some cases may meet or exceed a selected ratio of 37Cl to total Cl. It is to be appreciated that any known or to be developed enrichment techniques may be used to ensure the desired and/or selected 37Cl ratio concentration including but not limited to centrifuges, ion exchange columns, etc. In an embodiment all chloride-containing compounds may be created from as pure a feed of 37Cl as possible. For example, chloride-based fuel salt compounds may be created so that greater than 90%, 95%, 98%, 99% or even 99.9% of the chloride ions in the fuel salt are 37Cl. Alternatively, a chloride-based nuclear fuel may be developed to achieve any target or selected percentage amount of 37Cl to other chloride ions in the fuel or in different components of the fuel. For example, for a fuel designed for thermal reactions, the chloride-based fuel salt compounds may be created so that less than 10%, 5%, 2%, 1% or even 0.1% of the chloride ions in the fuel salt are 35Cl, the remaining being 37Cl. For fuels tailored to fast reactions, the chloride-based fuel salt compounds may be created so that greater than 10%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or more up to 100% as described above of the chloride ions in the fuel salt are 37Cl. Modelling has indicated that MCFR performance improves significantly with chlorine that is enriched to at least 75% 37Cl. The use of enriched chlorine reduces both neutron parasitic absorption and production of 36Cl, which is a long-lived activation product. FIG. 3 illustrates an embodiment of a method for creating a fuel tailored to a specific reactor. This adjustment of the relative amounts of 35Cl to 37Cl provides an additional method to control the reactivity of the fuel salt in fast or thermal reactions. The method 300 begins with an identification operation 302. In the identification operation 302, the desired ratio of 37Cl to total Cl is determined. To determine the appropriate ratio, factors such as the reactor design, the desired operating parameters of the reactor (e.g., temperature, pressure, etc.), and the chloride-based compounds to be used in the fuel may be taken into account. The fuel identification operation 302, for example, may include choosing an initial Cl salt having a second ratio of 37Cl to total Cl in the fuel and determining an initial effective neutron multiplication factor (keff) for the reactor using the initial molten chloride fuel salt, comparing the initial effective neutron multiplication factor to the target effective neutron multiplication factor, and calculating the next or final ratio of 37Cl to total Cl based on results of the comparing operation. A target effective neutron multiplication factor (ken) may be identified based on the desires of the manufacturer or operator of the nuclear reactor. These techniques may be iterated and/or adjusted as appropriate to determine 302 the selected ratio of 37Cl to total Cl. A fuel generation operation 304 is then performed. In the fuel generation operation 304, a fuel is created by modifying the ratio of 37Cl to total Cl in the final fuel. In an embodiment, the modified molten chloride fuel salt includes a mixture of different chloride compounds including a first fissile chloride salt compound and a first non-fissile chloride salt compound. In this embodiment, the fuel generation operation 304 may include generating the first fissile chloride salt compound and the first non-fissile chloride salt compound so that they have different ratios of 37Cl to total Cl of the first fissile chloride salt compound or first non-fissile chloride salt compound, respectively. The 37Cl to total Cl ratio of each compound is adjusted so that upon combination of the two (or more) compounds to form the final modified fuel salt mixture, the modified molten chloride fuel salt has the desired ratio of 37Cl to total Cl based on the mass balance of the compounds and their respective 37Cl to total Cl ratios. The result of the fuel generation operation 304 is a modified molten chloride fuel salt having a first ratio of 37Cl to total Cl in the modified molten chloride fuel salt that, when used in the nuclear reactor, achieves the target effective neutron multiplication factor. The fuel salt is referred to as ‘modified’ to recognize that the final ratio is different than the naturally occurring ratio of 37Cl to total Cl. For example, a fuel salt may be a mixture of 33% UCl4, 33% UCl3 and 33% NaCl and, in order to achieve a final modified fuel salt ratio of 40% 37Cl to total Cl, the NaCl may be enriched to have a ratio of 75% 37Cl to total Cl while the naturally occurring ratio is used for the other two components. This results in a final modified UCl4-UCl3—NaCl fuel salt having a ratio of 40% 37Cl to total Cl. The preceding example also shows that, for efficiency, it may be decided to enrich only one compound of a multi-compound fuel salt mixture. For example, if a non-fissile chloride salts is included in the final fuel salt, a large amount of high (or low)37Cl to total Cl ratio salt may be created and maintained for later use in blending fuel. The refining of 37Cl from naturally occurring chlorine is known in the art and any suitable method may be used. For example, centrifugal or ion exchange column (IXC) methods of enrichment appear viable and extensible to the required quantities. Other methods are also possible. After the modified fuel has been generated, the reactor is charged with the modified fuel and the reactor is operated using the modified fuel in a reactor operation 306. If it is determined during operation that the reactivity is not optimal, new fuel may be generated using the method 300 to either replace the existing fuel or to be blended with the existing fuel until the desired reactivity is achieved in a subsequent fuel generation and blending operation (not shown). In yet another embodiment, the method 300 may be used to change or maintain the reactivity over time in a reactor. As discussed in greater detail below, chloride-containing fuel salts may include one or more of UCl4, UCl3, UCl3F, UCl2F2, and UClF3 and/or any of the specific fuel salt embodiments described herein may be modified as described above. If a non-fissile chloride compound is used, such additional metal chloride salt may be selected from NaCl, MgCl2, CaCl2, BaCl2, KCl, SrCl2, VCl3, CrCl3, TiCl4, ZrCl4, ThCl4, AcCl3, NpCl4, AmCl3, LaCl3, CeCl3, PrCl3 and/or NdCl3. UCl3-UCl4—[X]Cln Fuel Salts Embodiments of uranium salts suitable for use as nuclear fuel includes salts that are a mixture of from 0-100% UCl3, 0-100% UCl4 and 0-95% of a metal chloride salt. Thus, these salts include 100% UCl3 fuel salt, 100% UCl4 fuel salt, as well as fuel salts that are mixtures of UCl3 and/or UCl4 with or without an additional metal chloride salt. Based on the results for NaCl as the additional metal chloride salt, fuel salts having a NaCl content less than 68 mol % are considered suitable based on the modelling results. In another embodiment, uranium salts suitable for use as nuclear fuel includes salts that are a mixture of from 0-100% UCl3, 0-100% UCl4 and 0-95% of a metal chloride salt having a melting point below 800, 700, 600, 500, 400 or 350° C. For NaCl embodiments, uranium salts suitable for use as nuclear fuel include salts that are a mixture of from 0-100% UCl3, 0-100% UCl4 and 0-68% of NaCl having a melting point of each of the constituent salts below 800, 700, 600, 500, 400 or 350° C. In yet another embodiment, NaCl content of the fuel salt may vary between 12 and 68% of NaCl. The molten chlorides differ significantly from the historically used fluorides in two noteworthy aspects. First, chlorides are less effective at moderating neutrons than the fluorides. This ensures a fast neutron spectrum, which is essential to breed-and-burn operation. Second, and more importantly, the chlorides offer the possibility of very high heavy metal concentrations in mixtures with reasonable melting points, which is important to obtain a compact fast breeding reactor design. Fluoride salts typically contain no more than 10-12 mole % heavy metal with proposed salt mixtures typically containing molar concentrations of 63-72 mole % LiF (enriched to 99.997% 7Li), 16-25 mole % BeF2, 6.7-11.7 mole % ThF4, and only 0.3 mole % UF4 (heavy metal is 40-45%, by weight). FIG. 4 illustrates a ternary phase diagram calculated for UCl3-UCl4—NaCl fuel salts based thermodynamic models. The diagram 400 shows the expected melting temperature for any mixture of UCl3-UCl4—NaCl. Of particular interest are mixtures having a melting point less than 500° C., which mixtures are illustrated in the shaded region 402 of the diagram 400. The eutectic point 404 has a melt temperature of 338° C. and a composition of 17UCl3-40.5UCl4-42.5NaCl (i.e., 17 mol % UCl3, 40.5 mol % UCl4 and 42.5 mol % NaCl). The shaded region 402 indicates a melting point envelope of 500° C. Moving to the far-right of this envelope 402 provides an embodiment, 17UCl3-71UCl4-12NaCl, but note that many possible compositions exist within the envelope 402 as embodiments of fuel salt mixtures having a melting point below 500° C. Furthermore, if the melting temperature limit is slightly extended to 508° C., a composition of 34UCl3-66NaCl provides an option that is free of UCl4. Likewise, the ternary diagram 400 allows a range of specific UCl3-UCl4—NaCl fuel salt embodiments to be identified for any given melting point limit from 800° C. and 338° C. For example, ternary salts with melting points from 300-550° C., 338-500° C., and 338-450° C. may be easily identified. The specific composition of the mixture may include any formulation including two or more of UCl4, UCl3 or NaCl such that the resulting uranium content level and melting temperature achieve desired levels. By way of non-limiting example, the specific composition may be selected so that the corresponding melting temperature falls from 330 and 800° C. By way of another non-limiting example, the specific composition may be selected so that the overall uranium content level is at or above 61% by weight. In addition to selecting the overall uranium content level the fuel composition may also be determined to meet a selected amount of fissile uranium (as opposed to fertile). For example, the specific composition of the fuel salt 108 may be selected such that the 235U content of the fuel salt 108 is below 20%. As part of initial concept development, a series of neutron transport and burn calculations have been completed for a variety of fuel salts, fissile enrichments, sizes and powers. As would be expected, higher enrichments enable smaller core sizes, but suffer from reduced breeding potential. Systems with some form of fission product removal can reach equilibrium behavior, while others breed up and then are eventually overwhelmed by the build-up of fission products. Multiple options exist for fuel salt selection, each with benefits and risks. The following discussion will identify particular embodiments of interest, however the following discussion does not limit the scope of the invention as claimed to only the embodiments described below, but rather, that any embodiments identifiable from FIG. 4 are contemplated, as well as any embodiments having different metal chlorides other than NaCl. Examples of additional, non-fissile metal chlorides include NaCl, MgCl2, CaCl2, BaCl2, KCl, SrCl2, VCl3, CrCl3, TiCl4, ZrCl4, ThCl4, AcCl3, NpCl4, AmCl3, LaCl3, CeCl3, PrCl3 and/or NdCl3. UCl4 Fuel Salt Embodiments In one embodiment, fuel salt 108 includes UCl4. For example, the fuel salt 108 may have a UCl4 content at or above 5% by molar fraction. In another embodiment, the fuel salt 108 of the reactor 100 may include a mixture of UCl4, an additional uranium chloride salt and/or an additional metal chloride salt (e.g., carrier salt) such that the UCl4 content of the mixture is at or above 5% by molar fraction. In other embodiments, the UCl4 content of the mixture may be at or above 0.01% by molar fraction, 0.1%, 0.5%, 1%, 2%, 3% or 4% UCl4. It is noted that fuel salt 108 having a UCl4 content at or above 5% by molar fraction may experience increased levels of corrosive exposure. As discussed below, a variety of approaches may be implemented to mitigate corrosion caused by increased chloride content. In another embodiment, the fuel salt 108 of the reactor may include a mixture of UCl4, an additional uranium chloride salt and/or an additional metal chloride salt such that uranium concentration of the mixture is at or above 61% by weight. In one embodiment, the additional uranium chloride salt includes UCl3, as is described in greater detail below. In another embodiment, the additional metal chloride salt may include a carrier salt, a fission product chloride salt, an actinide chloride salt and/or a lanthanide chloride salt. By way of non-limiting example, the additional metal chloride salt may include, but is not limited to, NaCl, MgCl2, CaCl2, BaCl2, KCl, SrCl2, VCl3, CrCl3, TiCl4, ZrCl4, ThCl4, AcCl3, NpCl4, AmCl3, LaCl3, CeCl3, PrCl3 and/or NdCl3. By way of non-limiting example, the fuel salt 108 of the reactor 100 may include a mixture of UCl4 and UCl3 (with no NaCl) such that the composition of the mixture corresponds to 82UCl4-18UCl3 (in molar %). It is noted that such a fuel salt composition has a uranium content of approximately 65% by weight and a melting temperature of 545° C. By way of another non-limiting example, the fuel salt 108 of the reactor 100 may include a mixture of UCl4, UCl3 and NaCl such that the composition of the mixture corresponds to 17UCl3-71UCl4-12NaCl (in molar %). It is noted that such a fuel salt composition has a uranium content of approximately 61% by weight and a melting temperature of approximately 500° C. By way of another non-limiting example, the fuel salt 108 of the reactor 100 may include a mixture of UCl4 and NaCl (with no UCl3) such that the composition of the mixture corresponds to 50UCl4-50NaCl (in molar %). It is noted that such a fuel salt composition will have a melting temperature of approximately 368° C. It is noted herein that, as the lanthanides and/or plutonium build up within the fuel salt 108, they may act similar to UCl3, since lanthanides and plutonium form trichloride compounds (as discussed above). In this event, the change in composition may cause the behavior of the fuel salt 108 to shift toward that of the eutectic (as discussed above), thereby reducing the melting point of the composition. By way of yet another example, pure UCl4 may be used as a fuel salt. Pure UCl4 has a melting temperature (as shown in FIG. 4) of 590° C. Due to the lower uranium content of the 66NaCl-34UCl3 composition, the binary salt requires a larger core than the UCl4-containing compositions in order to achieve initial criticality. For example, the reactor core section 102 may require a volume 3-4 times larger than required for a UCl4-containing version of the fuel salt 108 to achieve initial criticality. FIG. 5 illustrates keff modeled as a function of time for a larger reactor core section of the reactor illustrated in FIGS. 1A-1F utilizing the 66NaCl-34UCl3 composition. Curve 502 depicts a modeled keff curve for a power level of 5800 MW and curve 504 depicts a modeled keff curve for a power level of 3420 MW. It is noted that both curves 502, 504 are modeled to operate with a depleted uranium (DU) feed and without specific lanthanide removal. As shown in FIG. 5, the 3420 MW case (curve 504) may operate for nearly 70 years before going subcritical, while the 5800 MW case (curve 502) may operate for approximately 41 years prior to going subcritical. In addition, the model shown in FIG. 5 also predicted a fuel burnup of 43% without any lanthanide removal during the years of operation. Thus, the modeling shows that chlorine-based uranium fuel salt may be effective at reducing dependencies of prior molten salt reactors on enriched uranium to maintain criticality. FIG. 6 illustrates a process flow 600 representing example operations related to fueling a fast spectrum molten salt nuclear reactor, in accordance with one or more embodiments of the present disclosure. Although the operations of FIG. 6 are presented in the sequence(s) illustrated, it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Operation 602 of flow diagram 600 includes providing a volume of UCl4. By way of non-limiting example, a selected volume of UCl4 may be provided in a substantially pure form. By way of another non-limiting example, a selected volume of UCl4 may be provided in the form of a mixture of UCl4 with another salt, such as, but not limited to, a carrier salt (e.g., NaCl). Operation 604 of flow diagram 600 includes providing a volume of at least one of an additional uranium chloride salt or an additional metal chloride salt. By way of non-limiting example, the additional uranium chloride may include, but is not limited to, UCl3. In one embodiment, a selected volume of substantially pure UCl3 may be provided. In another embodiment, a selected volume of UCl3 may be provided in the form of a mixture of UCl3 with another salt, such as, but not limited to, a carrier salt (e.g., NaCl). By way of another non-limiting example, the additional metal chloride includes, but is not limited to, one or more NaCl, MgCl2, CaCl2, BaCl2, KCl, SrCl2, VCl3, CrCl3, TiCl4, ZrCl4, ThCl4, AcCl3, NpCl4, AmCl3, LaCl3, CeCl3, PrCl3 and/or NdCl3. In one embodiment, a selected volume of an additional metal chloride may be provided. In another embodiment, a selected volume of an additional metal chloride may be provided in the form of a mixture of the metal chloride with another salt, such as, but not limited to, a carrier salt. Operation 606 of flow diagram 600 includes mixing the volume of UCl4 with the volume of the at least one of an additional uranium chloride salt or an additional metal chloride salt to form a molten chloride nuclear fuel salt having a UCl4 content greater than 5% by molar fraction. By way of non-limiting example, the volume of UCl4 provided in operation 602 may be mixed with the volume of operation 604 such that the resulting molten chloride salt mixture has a UCl4 content greater than 5% by molar fraction. In this regard, the volume of UCl4 of operation 602 and the volumes of additional uranium chloride and/or an additional metal chloride may be selected such that the resulting molten chloride salt mixture has a UCl4 content greater than 5% by molar fraction. Additionally or alternatively, operation 606 includes mixing the volume of UCl4 with the volume of the additional uranium chloride salt and/or additional metal chloride salt to form a molten chloride salt mixture having a melting temperature from 330 to 800° C. In one embodiment, the volumes of operations 602 and 604 may be selected and mixed such that the resulting molten chloride salt mixture has a chemical composition of (or approximately) 82UCl4-18UCl3. In another embodiment, the volumes of operations 602 and 604 may be selected and mixed such that the resulting molten chloride salt mixture has a chemical composition of (or approximately) 17UCl3-71UCl4-12NaCl. In another embodiment, the volumes of operations 602 and 604 may be selected and mixed such that the resulting molten chloride salt mixture has a chemical composition of (or approximately) 50 UCl4-50NaCl. Operation 608 of flow diagram 600 includes supplying the molten chloride nuclear fuel salt having some amount of UCl4 as described above (e.g., the UCl4 content of the mixture may be at or above 0.01% by molar fraction, 0.1%, 0.5%, 1%, 2%, 3%, 4% or 5%) to at least a reactor core section of the fast spectrum molten salt nuclear reactor. In one embodiment, the mixture of operation 606 may be formed by mixing the volume of UCl4 with the volume of the at least one of an additional uranium chloride salt or an additional metal chloride salt inside of the fast spectrum molten salt nuclear reactor. In one embodiment, the mixture of operation 606 may be formed by mixing the volume of UCl4 with the volume of the at least one of an additional uranium chloride salt or an additional metal chloride salt at a location outside of the fast spectrum molten salt nuclear reactor, such as, but not limited to, a mixing vessel. In this regard, following the mixture of UCl4 with the volume of the at least one of an additional uranium chloride salt or an additional metal chloride salt, the molten chloride salt mixture may be loaded into the reactor 100. The reactor may then be operated as described herein, for example by initiating fission in the fuel salt and then maintaining breed-and-burn behavior in the reactor core for some period of time. In one embodiment, the concentration of one or more of the additional metal chlorides (discussed above) is selected to be at or below the precipitation concentration for precipitation of the additional metal chloride within the nuclear fuel mixture. For instance, a fission product concentration may be kept below the concentration associated with that fission product that would cause another constituent, such as Pu, of the fuel salt 108 to precipitate out of the fuel solution. It is again noted that the molten chloride salt compositions provided above are not limitations on the reactor 100 or associated methods of the present disclosure. Rather, the specific compositions are provided merely for illustrative purposes. It is recognized that any molten chloride fuel salt may be implemented in the reactor 100 of the present disclosure. UCl3 Fuel Salt Embodiments In addition to the embodiments described above that contained UCl3 in combination with UCl4, additional embodiments of the fuel salts include UCl3 and lack any UCl4 content. These embodiments and their associated melting points are also identified on FIG. 4 along the left axis. It is noted that a fuel mixture free of UCl4 may be of particular interest in the event UCl4 corrosion concerns become significant and may lessen the need for corrosion mitigation techniques (as described below). By way of non-limiting example, the fuel salt 108 of the reactor 100 may include a mixture of UCl3 and NaCl such that the composition of the mixture corresponds to 66NaCl-34UCl3 (in molar %). It is noted that such a fuel salt composition has a melting temperature of approximately 508° C., but a reduced uranium content level as compared to the UCl4-containing compositions (described above). UCl3 fuel salt embodiments also include pure UCl3, however, the melting point is slightly above 800° C. and thus this embodiment may not be suitable for certain reactor designs. Mixed Chloride-Fluoride Fuel Salt Embodiments Mixed chloride-fluoride salts of actinides, and particularly of uranium, may also be suitable fissionable salts for use in a molten salt reactor. UCl3F is an embodiment of a potentially useful chloride-fluoride salt. UCl3F has a melting point of from 410-440° C. which is less than the melting point of pure UCl4, which is 590° C. Because of the molecular symmetry and chemical composition of the UCl3F salt, it is also anticipated that UCl3F will have a lower volatility than UCl4 making it even more attractive as a fuel salt in a low temperature (e.g., less than 800° C., or even less than 550° C.). molten salt reactor. Based on the above information, the calculated ternary diagram for UCl4 shown in FIG. 4, and the similarity between UCl3F and UCl4, it is expected that UCl3F could be used to replace some or all of the UCl4 in a fuel salt mixture to obtain fuel salt embodiments that have even better properties (e.g., lower melting point and lower volatility) while having substantially the same reactivity. Although a ternary diagram of UCl3F, UCl3 and NaCl has not been calculated, a ternary diagram for UCl3F, UCl3 and NaCl is anticipated to show a minimum melting point at a location near the corresponding eutectic point 404 on FIG. 4 for the salt 17UCl3-40.5UCl4-42.5NaCl. That is, it is anticipated that such a diagram for UCl3F, UCl3 and NaCl will show a similar trend in reduced melting point in a region from 15-20 mol % UCl3 and the balance being from 35-45 mol % NaCl and 35-45 mol % UCl3F. Given that UCl3F normally has a melting point substantially less than UCl4, replacing UCl4 with UCl3F in fuel salt embodiments is anticipated to result in fuel salts with even lower melting points than those observed in FIG. 4. Given this information, uranium embodiments of Cl3F fuel salts include salts having from 1-100 mol % UCl3F. For example, embodiments of mixed chloride-fluoride fuel salts include salts with at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 99% UCl3F. A fuel salt of pure or substantially pure UCl3F is also possible, as the melting point is within the operational range of the reactors described herein. In an alternative embodiment, a UCl3F fuel salt may have only a detectable amount of UCl3F. While it is recognized that detection limits may change as technology improves, in an embodiment a detectable amount means equal to or greater than 0.01 mol %. Other salts that could be combined with UCl3F to make fuel salt embodiments include, UCl3, NaCl, and UCl4. As discussed above salts of UCl3F—UCl3—NaCl are particularly contemplated including embodiments having from 15-20 mol % UCl3 and the balance being from 35-45 mol % NaCl and 35-45 mol % UCl3F. In addition, any other salts discussed herein may be included, such as ThCl4, uranium fluoride salts, non-fissile salts, and uranium bromide salts. In addition to UCl3F, other mixed actinide salts such as UCl2F2, and UClF3 may be suitable for use as a fuel salt or a constituent of a fuel salt in a molten reactor. Mixed chloride-fluoride salts of plutonium or thorium may also be suitable for use as molten fuel salts. Embodiments of methods for creating UCl3F, UCl2F2, and UClF3 are described below including an experiment in which UCl3F was created. Modified chloride fuel salt embodiments having an altered ratio of 37Cl to total Cl are also possible and may be used for molten fuel salts. In addition, mixed chloride fluoride fuel salt embodiments may include non-fissile chloride compounds in addition to or instead of NaCl, such as MgCl2, CaCl2, BaCl2, KCl, SrCl2, VCl3, CrCl3, TiCl4, ZrCl4, ThCl4, AcCl3, NpCl4, AmCl3, LaCl3, CeCl3, PrCl3 and/or NdCl3. In use, mixed uranium chloride-fluoride salt embodiments will be used in a similar fashion to that described above for the chloride salt embodiments. For example, the desired salt composition, such as from 15-20 mol % UCl3 and the balance being from 35-45 mol % NaCl and 35-45 mol % UCl3F, is created. This may be done remotely or by adding the constituents directly into the reactor core. The constituents may be added in solid or liquid form. After charging the reactor core with the fuel salt, the reactor is then brought to operating conditions to initiate a chain reaction, as described above. Thorium Chloride Fuel Salt In one embodiment, the fuel salt 108 may include a selected amount of thorium. By way of example, in the case of a chloride-based nuclear fuel salt, the thorium may be presented in the fuel salt 108 in the form of thorium chloride (e.g., ThCl4). Methods for manufacturing ThCl4 are known in the art and any suitable method may be used. The introduction of ThCl4 into chloride-salt systems has been shown to reduce the melt temperature of the system by approximately 50° C. Thus, based on the information from the ternary salt diagram of FIG. 4, ThCl4 embodiments should have a melting point at or below those found in the ternary system and should be capable of supporting a breed-and-burn reaction while in the molten state. For example, melting points below 800° C. and even 550° C. should be achievable based on the information from the ternary diagram. An embodiment utilizing ThCl4 is UCl3F—UCl4-UCl3—ThCl4—[X]Cl where, as above, [X]Cl is any additional, non-fissile salt. In these embodiments, the mol ratios of the any of various chloride salt may be determined as needed to obtain the desired melting point. In an embodiment, the amount of ThCl4 varies from a detectable amount of ThCl4 and 80 mol % and the other components (i.e., UCl3F, UCl4, UCl3, and [X]Cl) vary independently from 0 to 80%. Thus, embodiments such as UCl3F—ThCl4—[X]Cl, and UCl3—ThCl4—[X]Cl are contemplated as are UCl4-UCl3—ThCl4—NaCl. Uranium Bromide Fuel Salt Embodiments In addition to the chloride fuel salt embodiments described herein, bromide fuel salts are also possible as an alternative or backup to a chloride fuel salt. A feature of a molten chloride fuel salt reactor is the ability to breed-and-burn its own fissile fuel from fertile fuel because of the very fast neutron spectrum. This is enabled by the use of an enriched chloride salt to bind the actinide atoms. Chlorine is generally a poor neutron moderator relative to other materials like water, graphite or fluorine. It also has a relatively low neutron capture cross section for parasitic capture (wasted neutrons). A well-performing salt constituent would create a strong chemical bond with actinides, exist with a low vapor pressure, be high Z number to enable a fast spectrum, and have a low (n,γ) capture cross section. 37Cl is an excellent choice as discussed above. However, based on this analysis bromine may also be suitable. Bromide salt (UBr3, UBr4) is in the same group and will have similar chemical properties to chloride salts. Bromine is a higher Z material than Cl, so it should moderate neutrons less and result in a faster spectrum. Bromine's chemical bond should be similar to that of Cl. These features make it an attractive alternative to a Cl salt. UBr4 has a reported melting temperature of 519° C., lower than that of UCl4, and so should be suitable for use in the systems and methods described herein. While the boiling point of UBr4 is reported as 791° C. so operating at high temperatures is likely not possible, this is not a limitation for nuclear reactors that are designed to operate in some of the lower ranges identified herein, e.g., 330-550° C., 338-500° C. and 338-450° C. FIG. 7 illustrates the (n,γ) capture cross section for the main Cl and Br isotopes, which illustrates that the (n,γ) capture cross section of Br is higher than Cl in most of the energy spectrum. In fact, 37Cl (curve 708 of FIG. 7) has a lower capture cross section throughout almost the entire spectrum when compared to 79Br (curve 706 of FIG. 7) and 81Br (curve 704 of FIG. 7). The 35Cl (curve 702 of FIG. 7) is also generally lower than the Br above 1×10−4 MeV. In addition, the suitability of a bromide salt to actually support a breed-and-burn reaction was studied. This study started with the same chemical makeup of salt and enrichment of the baseline chloride salt. These were 17UBr3-71UBr4-12NaBr and 12.6% 235U enrichment. This fuel salt was modeled in a standard 1 GWth molten chloride fast reactor with no other changes. The resulting system was subcritical and required either increasing the reactor core size or increasing the enrichment. Increasing the enrichment to 19.99% (maximum allowed to be considered low enriched fuel) in the model resulted in a breed-and-burn curve is shown in FIG. 8. The reactor starts at an artificially high keff, burns down for a few decades, but eventually breeds enough Pu and minor actinides to increase keff again. Even without being optimized for the bromide salt system, the results of the modelling in FIG. 8 illustrate that the bromide fuel salt embodiments do breed-and-burn and that a molten bromide salt reactor can operate. Thus, UBr3 and/or UBr4 containing fuel salts in which the fuel salts are enriched with 235U at levels greater than 19% are suitable. There exist a number optimization possibilities to maximize performance while minimizing volumes necessary to support a breed-and-burn reaction. First, a minimum enrichment may be found to ensure breed-and-burn performance without falling subcritical. Second, reflector sizing and material configurations could be used to tailor the spectrum in a region that maximizes breeding. Third, consistent with the chloride embodiments described above, different fuel salt combinations (XXUBr3—YYUBr4—ZZNaBr) could be investigated to find the optimal embodiments. In addition, the bromide anions used in one or components of the salt could be modified similar to that described with chloride salts using 37Cl. As shown in FIG. 7, the two stable isotopes of bromine, 79Br and 81Br, have different neutron capture cross sections. Thus, the capture characteristics of the salt can be tailored by modifying the ratio of these isotopes used in the bromide salts. In an embodiment all bromide-containing compounds may be created from as pure a feed as possible of either 79Br or 81Br. For example, bromide-based fuel salt compounds may be created so that greater than 90%, 95%, 98%, 99% or even 99.9% of the bromide ions in the fuel salt are either 79Br or 81Br. Alternatively, a bromide-based nuclear fuel may be developed to achieve any target or selected percentage amount of either 79Br or 81Br or a combination of the two to other bromide ions in the fuel or in different components of the fuel. For example, in an embodiment, the bromide-based fuel salt compounds may be created so that less than 10%, 5%, 2%, 1% or even 0.1% of the bromide ions in the fuel salt are 81Br, the remaining being 79Br. Alternatively, the bromide-based fuel salt compounds may be created so that greater than 10%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or more up to 100% as described above of the bromide ions in the fuel salt are 81Br. Uranium Chloride Fuel Manufacturing Processes Various methods of manufacturing of UCl4 and UCl3 are known in the art and any suitable method may be used. For example, UCl4 may be manufactured by the chemical reaction:UO3+Cl3CCCl═CCl2→UCl4+byproductLikewise, UCl3 may be manufactured using either of the following reactions:U+3/2H2→UH3 and UH3+3HCl→UCl3+3H2 UCl4+Cs→UCl3+CsClUsing the above methods, any amount of UCl4 and UCl3 may be created and then blended to form any of the uranium chloride fuel salt embodiments described above. In addition to the above methods, the following describes another method that can efficiently and simply create a UCl4-UCl3—NaCl embodiment. Synthesized salts will be subject to strict chemical control to minimize corrosion and precipitation of nuclear material. These chemical controls revolve around eliminating the formation of oxides and hydroxides, especially associated with the uranium cation, which are all more stable than their chloride counterparts. Therefore, once component salts are manufactured they must not contact oxide layers, oxygen, or water, for the duration of their lifetime. To satisfy this stringent requirement, one may purify and process salts under an inert atmosphere, in a closed container. When component salts are required to be mixed, the operation should be performed without exposure to air, water, or oxygen. Storage should be done within leak tight, oxide free, canisters with a positive partial pressure of inert gas. These strict purity actions coupled with the isotopic enrichment and high temperatures lead to unique challenges. While there are many simpler lab scale processes, it is proposed that a four-step process be used to create high purity, chlorine-37 enriched, and chloride salt mixtures. First, uranium dioxide and sodium carbonate should be reacted in tandem below liquidus temperatures, in vessels coupled in series, with a controlled mixture of chlorine and carbon monoxide gas yielding uranium tetrachloride, sodium chloride, and carbon dioxide gas. Second, the uranium tetrachloride is heated below its liquidus temperature and dry argon is slowly passed over it, facilitating its sublimation and subsequent transfer through heated lines into the cooler bed of fresh sodium chloride. Third, a charge of silicon is added to the UCl4—NaCl mixture and allowed to react in the liquid phase, producing silicon tetrachloride, which can be sparged from the salt. Other reducing agents can be used instead of Si and will be examined if necessary. Fourth, the salt is transferred into a storage container and cold stored under argon. FIG. 9 illustrates an embodiment of a method of manufacturing a fuel salt containing UCl4 based on the process outlined above. In the embodiment shown, the method starts with a uranium dioxide contacting operation 902. In the uranium dioxide contacting operation 902, a volume of UO2 is brought into contact with gaseous chlorine and carbon monoxide at a temperature that allows the formation of UCl4. In an embodiment, this operation may be performed by providing an amount of solid UO2. By providing the solid UO2 in a high surface area form that allows easy contact with a gas, such as a powder, a particulate or a porous matrix, the reaction can be made more efficient. The result of the contacting operation 902 is that at least some of the UO2 that comes in contact with the gases is converted into UCl4 via the carbochlorination reaction:UO2(s)+2CO(g)+2Cl2(g)=UCl4(s)+2CO2(g) This reaction is unique as it contains both a reductant, carbon monoxide, and oxidizer, chloride. These two components oscillate uranium's oxidization state from IV to VI in order to satisfy the thermodynamics of producing uranium tetrachloride from the much more stable oxide. The reaction is very complex in terms of partial reactions. It can be thought of, in order, asUO2(s)+½Cl2(g)→UO2Cl; Oxidization,UO2Cl+½Cl2(g)→UO2Cl2(s); Oxidation,UO2Cl2(s)+CO(g)→UOCl2+CO2(g); Reduction,UOCl2(s)+½Cl2(g)→UOCl3(s); Oxidation,UOCl3(s)+½Cl2(g)→UOCl4; Oxidation,UOCl4+CO(g)→UCl4+CO2(g); Reduction.It is important to note that two reactions are predicted after the tetrachlorideUCl4+½Cl2(g)→UCl5; Oxidation,UCl5+½Cl2(g)→UCl6; Oxidation. Two oxidization reactions are known to produce uranium pentachloride and uranium hexachloride, but these products are predicted to decompose to uranium tetrachloride at 250° C. To avoid the production of uranium pentachloride and uranium hexachloride, and the melting or sublimation of the uranium tetrachloride as well, the reaction may be kept between the temperatures of 250° C. and 400° C. As described above, some or all of the chlorine may be 37Cl in order to achieve a target 37Cl to total Cl in the resulting UCl4 or the Cl in the fuel overall as discussed above. Depending on the desired ratio, multiple sources of different isotopes of Cl may be used to achieve the desired 37Cl to total Cl ratio, e.g., a source of pure 37Cl, a source of natural Cl, a source of pure 35Cl and/or some other blend of 35Cl and 37Cl. The method 900 also includes a sodium carbonate (Na2CO3) contacting operation 904. Similar to the UO2 contacting operation 902, the Na2CO3 contacting operation 904, includes contacting a volume of Na2CO3 with gaseous chlorine and carbon monoxide at a temperature that allows the formation of NaCl. In an embodiment, this operation may be performed by providing an amount of solid Na2CO3. By providing the solid Na2CO3 in a high surface area form that allows easy contact with a gas, such as a powder, a particulate or a porous matrix, the reaction can be made more efficient. The result of the sodium carbonate contacting operation 904 is that at least some of the Na2CO3 that comes in contact with the gases is converted into NaCl. Again, as described above, the amount of Cl enrichment (e.g., 37Cl enrichment) in the final NaCl can be controlled by controlling the enrichment in the chlorine gas used. The equation for this reaction is as follows:Na2CO3(s)+CO(g)+Cl2(g)=2NaCl(s)+2CO2(g) The method 900 also includes silicon contacting operation 906 in which liquid or gaseous UCl4 is contacted with silicon metal. In an embodiment, the silicon contacting operation 906 may control the reaction conditions to cause a specified UCl4—Si reaction or reactions to occur, whereby the amount of UCl3 generated is controlled by the amount of Si used and UCl4 is provided in excess. This operation 906 may be performed by providing an excess amount of liquid UCl4 and immersing a known amount of silicon in the liquid until all or substantially all the Si has reacted. The result of the silicon contacting operation 906 is that at least some of the UCl4 that comes in contact with the gases is converted into UCl3. The amount of UCl4 that is converted to UCl3 is stoichiometric with the amount of Si used as the Si is highly reactive with UCl4 but not with UCl3. Therefore, with a known starting amount of UCl4, any desired mixture of UCl4-UCl3 can be obtained simply by controlling the amount of Si placed into contact with the UCl4 gas and the amount of UCl4. An equation for a suitable reaction that could be used in this embodiment of the operation 906 is as follows:4UCl4(g or l)+Si(s)=4UCl3(g)+SiCl4(g) Silicon tetrachloride boils at 57° C., which at molten salt temperatures will readily vaporize and be carried away with the argon. Once removed it can be collected or reacted with a neutralization bath. The naturally existing oxide layer, silicon dioxide, is inert to the salt and will exist as a suspension or settle as a precipitate. Its presence will not affect the quality of the salt. Other reactions are also possible. For example, the silicon contacting operation 906 may involve using silane (SiH4) or another silicon containing gas such as silicon dichloride (SiCl2) under the temperature and pressure conditions to allow the formation of UCl3 and SiCl4 from the UCl4. The UCl4 may be either in gaseous or solid form during this reaction, depending on the temperature and pressure conditions. In an alternative embodiment, rather than using an excess of UCl4 the silicon contacting operation 906 may instead convert a known amount of UCl4 to the same stoichiometric amount UCl3 in an excess of Si. As the goal is to generate a known amount of UCl3 and the resulting silicon chloride specie are unimportant, performing the silicon contacting operation 906 in an excess of Si may be simpler than controlling the reaction conditions. The contacting operations 902, 904, 906 may be performed using any suitable contacting vessels or equipment, now known or later developed. For example, in an embodiment the solid material to be contacted is a loose particulate or powder and the gaseous material is flowed or circulated under pressure through the contacting vessel (e.g., flowed into a valve at one end of the vessel and removed from a valve at the other end of the vessel) such that the vessel temporarily becomes a packed bed reactor or, if the flow rate through the container is sufficient, a fluidized bed reactor. In these embodiments, the contacting of the gases with the solid material is performed without removing solid material from the vessel container. The method 900 further includes mixing the generated UCl3, UCl4 and NaCl to obtain the desired fuel salt embodiment. The mixing may be done while the UCl3, UCl4 and NaCl are, independently, in the gas, liquid or solid phase. For example, the appropriate amount of each compound may be created separately, then the separate compounds may be heated to the molten state and transferred into a single container where they are allowed to mix and solidify. This creates a solid fuel salt embodiment that is easily transported. As previously noted, the components can be mixed and/or melted within or external to the reactor vessel. The method 900 may be performed as independent operations or may be performed in a way that the execution of the operations is coordinated. For example, the same chlorine gas may be used in the UO2 contacting operation 902 and the Na2CO3 contacting operation 904 by connecting the contacting vessels. FIG. 10 illustrates an embodiment of a coordinated method of manufacturing a fuel salt containing UCl4 based on the method of FIG. 9. In the coordinated method 1000, a first contacting vessel containing solid UO2, a second contacting vessel containing solid Na2CO3 and a collection vessel containing element Si solid are provided in a system preparation operation 1002. This operation 1002 also includes providing the Cl2 and CO as well as bringing all of the components of the system up to the appropriate operating conditions, e.g., from 200-550° C. and 1-5 atm. In an embodiment, the vessels may be prepared with an inert gas, such as argon, filing the gas space around the solid contents. As discussed above, the Cl2 gas may have a modified amount of 37Cl (i.e., an amount different than the naturally occurring amount of 24% 37Cl) to change the neutron moderation and absorption of the Cl content in the final fuel salt. For example, in one embodiment the modified Cl2 may have less than 23% 37Cl. In another embodiment, the Cl2 gas may have greater than 25% 37Cl. FIG. 11 illustrates a schematic of the contacting vessels and their connections suitable for use in performing the method of FIG. 10. FIG. 11 shows a first contacting vessel 1102 holding solid UO2, a second contacting vessel 1104 with solid Na2CO3, and a collection vessel 1106 containing silicon (Si) metal solid. The vessels 1102, 1104, 1106 are connected such that gas can be flowed through the first vessel 1102 and then through the second vessel 1104. The collection vessel 1106 is further connected to the second vessel 1104 so that it can receive one or both of a gas or liquid from the second vessel 1104, such as via gravity or an induced pressure differential between the vessels 1104, 1106. In an alternative embodiment, the Si may be added to the second vessel 1104 or provided in an intermediate contacting vessel (not shown). A Cl2 source 1108, a CO source 1110 and an inert gas source 1112 are shown as gas cylinders, although any source may be used. In the embodiment shown, the CO and Cl2 are connected only to the first vessel 1102, while the inert gas (illustrated as argon although any inert gas may be used) is connected to all three vessels so that the environment in each vessel may be independently controlled. Ancillary components such as valves, filters, check valves, pressure and temperature sensors, flow monitors and flow controllers, heating and cooling equipment, pumps, and compressors are not illustrated, one of skill in the art who ready recognize how to implement these components to achieve the results described herein. Likewise, fittings and access ports, internal diffusion components and other elements may be used where needed and are not specifically identified on FIG. 11. Returning now to FIG. 10, after the system has been prepared in the preparation operation 1002, the Cl2 and CO are flowed through the first vessel 1102 and the second vessel 1104 of FIG. 11 in a reactant gas flowing operation 1004. This serves to contact the UO2 and the Na2CO3 with the Cl2 and CO so that UCl4 and NaCl are created, respectively, in each vessel. The gases may be flowed through each vessel 1102, 1104 once (single pass) or recirculated for some amount of time. For example, in an embodiment the reactant gas flowing operation 1004 may be performed until all of the UO2 has been converted into UCl4, until all of the Na2CO3 or both. Alternatively, the reactant gas flowing operation 1004 may be performed only for a fixed period of time sufficient to produce as much or more UCl4 and NaCl as currently necessary to create the final fuel salt. After flowing gases through the two vessels 1102, 1104, the gases may be collected for reprocessing and reuse. In particular, if an enriched Cl2 gas is used, it may be cost effective to recover as much of the Cl gas as possible. Alternatively, the gases could be treated and discharged to the environment, such as, for example, by passing the gases through a copper oxide scrubber which will reduce the CO. The amount of UCl4 and NaCl created will depend on the operating conditions and how long the gases are flowed through the vessels 1102, 1104. Thus, the operator can easily control the system 1100 to get a desired amount of each material. In addition, the relative size and shape of the vessels 1102, 1104 can be tuned so that a specific relative amount of NaCl is created for a given amount of UCl4 from a single operation. This allows the system to be configured to create any desired UCl4—NaCl fuel salt and, by extension as discussed in greater detail below with reference to operation 1012, any UCl3-UCl4—NaCl fuel salt. In the system embodiment shown in FIG. 11, the vessels are connected in series and the gases flow first through the first vessel and then through the second vessel. In an alternative embodiment, the gases may be flowed independently through each vessel. This alternative embodiment allows different sources (and therefore enrichments) of Cl2 to be used. After flowing gases through the two vessels 1102, 1104, thereby creating at least some UCl4 in the first vessel 1102 and NaCl in the second vessel 1104, a UCl4 gasification operation 1006 is performed in which the temperature and/or pressure of the first vessel 1102 is adjusted such that the UCl4 is converted from the solid phase to the gas phase. In an embodiment, the conversion is through sublimation and the UCl4 does not go through a liquid phase. In an alternative embodiment, the temperature and pressure conditions are adjusted so that the UCl4 is first converted into a liquid before it is boiled into a gas. In an embodiment, the gasification operation 1006 may maintain the sublimation conditions for a certain period of time selected so that most or all of the UCl4 is converted to the gas phase. In an embodiment the carbochlorination of uranium dioxide is run to completion. However, the extent of the reaction does not matter except for efficiency purposes. Any mixture of powdered uranium dioxide and uranium tetrachloride can be conveniently separated via uranium tetrachloride's high vapor pressure. Uranium tetrachloride has been found to sublimate at temperatures as low as 520° C. By heating up the uranium tetrachloride, for example in an embodiment to 520° C. (70° C. below its melting point), the UCl4 should be slowly volatilized and easily removed from any unreacted UO2. The UCl4 gasification operation 1006 may be performed after flushing all or most of the reactant Cl2 and CO gas from the first vessel 1102. The gaseous UCl4 is then transferred to the second vessel 1104 in a UCl4 transfer operation 1008. This may be achieved through any conventional means. Because UO2 has a higher melting point (2,865° C. at latm) than UCl4 has boiling point (791° C.), any UO2 remains in the first vessel as a solid. However, filters or dropouts may be provided to prevent any particulate from being unintentionally removed from the first vessel 1102 during the gas transfer. In an embodiment, all or substantially all of the UCl4 is transferred during this operation 1008. Alternatively, a known amount of UCl4 may be transferred based on the desired amount and proportion of the final fuel salt desired. Real-time flow meters and gas analyzers may be used to verify or control the amount transfers, as is known in the art. After the selected amount of UCl4 gas has been transferred to the second vessel 1104, the environment of the second vessel 1104 is adjusted so that the UCl4 gas is condensed and NaCl solid is melted, bringing both to a liquid state in a fuel salt melting operation 1010. In an embodiment in which the second vessel is maintained at a pressure of 1 atm, this environment corresponds to a temperature range of from 368° C. and 800° C. depending on the relative amounts of UCl4 to NaCl (as shown on the lower axis of the ternary diagram of FIG. 4). As the melting point of Na2CO3 is 851° C. at 1 atm, the environment can be easily adjusted to a point where the UCl4—NaCl mixture because liquid while the Na2CO3 is maintained in the solid state. In an embodiment, for example, the sodium chloride will be kept at 350° C., or 20° C. below the eutectic of UCl4—NaCl. After the fuel salt melting operation 1010, the some or all of the liquid UCl4—NaCl is then transferred into the collection vessel 1106 in a UCl4—NaCl transfer operation 1012. This may be achieved by any conventional means, such as pressurizing the second vessel 1104 with argon to displace the molten UCl4—NaCl mixture and drive it into the collection vessel 1106. Alternatively, the liquid could simply be decanted using gravity into the collection vessel 1106. Again, care and special equipment may be utilized to prevent any remaining Na2CO3 from being removed from the second vessel 1104. The system 1100 is further designed so that, upon entering the collection vessel 1106, the UCl4 in the liquid will come into contact with the Si in the collection vessel 1106. In an embodiment, the conditions will be controlled so that the Si reaction has the effect, described above, of stoichiometrically reacting with the UCl4 to form SiCl4 and UCl3. The collection vessel is maintained at an operating condition so that the UCl3 remains a liquid, while the SiCl4 is boiled off into a gas that can be easily removed. Therefore, by controlling the amount of Si in the collection vessel 1106, the amount of resulting UCl3 can be controlled. Because the system 1100 allows for easy control of the relative amounts of UCl4 and NaCl that ultimately are transferred into the collection vessel 1106, and the amount of UCl4 converted into UCl3 can also be easily controlled, any desired UCl3-UCl4—NaCl mixture can be made using the system 1100 and the method 1000. After the UCl4—NaCl transfer operation 1112, a final collection operation 1012 may be performed. In this operation 1012, the SiCl4 may be removed and replaced with an inert gas. The fuel salt may be solidified for easy transportation within the collection vessel 1106 or may be transferred into another container (in a liquid, solid or gaseous state) for storage or transportation. The kinetics of the reactions in the vessels 1102, 1104, 1106 will depend on the form of the solid UO2 and solid Na2CO3 used, e.g., powder, particulate, porous matrix, block, etc., and the flow, temperature and pressure conditions of the gases, as well as the internal configuration of the contacting vessels, e.g., they are configured to enhance contact with the flowing gases through the use of internal baffles, diffusers or other components. While any solid form of UO2 and Na2CO3 can be used, high surface area forms will enhance the kinetics of the reaction and be generally more efficient. Likewise, while any type of vessel, now known or later developed, may be used, contacting vessel designs specifically adapted to enhance solid-gas and liquid-gas contacting will be more efficient than simpler designs. In addition, active components such as mixers or agitators may be used in any or all vessels to enhance contacting, gasification or mixing during any of the operations of FIG. 9 or 10. While various embodiments of the UCl3-UCl4—NaCl fuel salt generation system 1100 and methods 900, 1000 have been described for purposes of this disclosure, various changes and modifications may be made which are well within the scope of the technology described herein. For example, one of skill in the art will recognize that many minor alterations to the system 1100 or methods 900, 1000 may be made while still achieving the same control over the final fuel salt mixture and final product. For example, solid silicon could be introduced into the second vessel 1104 or the solid silicon could be kept in a flow-through chamber (not shown) between the second vessel 1104 and the collection vessel 1106. Likewise, the first and second vessels could be operated independently, instead of serially, and the UCl4 gas and NaCl liquid could be separately transferred into the collection vessel 1106. Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the disclosure and as defined in the appended claims. In addition, the methods of FIG. 9 or 10 may be further adapted if a UCl3—NaCl binary mixture is desired. In this embodiment, the entire UCl4—NaCl mixture can be sparged with hydrogen for extended periods of time initiating the reaction:2UCl4+H2(g)=2UCl3+2HCl(g).By providing the excess H2, all of the UCl4 may be converted to UCl3.Synthesis of UCl4 from UO2 using Ammonium Chloride FIG. 16 illustrates an embodiment of a method for the manufacture of UCl4 using ammonium chloride. In the embodiment of the method 1600 shown, a mixture of solid UO2 and NH4Cl is created in a uranium preparation operation 1602. The solid mixture may be created using any conventional means such as grinding, crushing, or cutting with any suitable equipment such as a ball mill, rod mill, autogenous mill, SAG mill, pebble mill, roll grinder, stamp mill, etc. A first conversion operation 1604 is then performed, in which the solid mixture is exposed to HCl under the conditions appropriate to generate (NH4)2UCl6 by the reaction:UO2(s)+2NH4Cl(s)+4HCl(g)=(NH4)2UCl6.2H2OIn an embodiment, the conversion operation 1604 includes heating the solid mixture while exposing the mixture to the HCl gas in an enclosed environment to 100° C. at 1 atm and maintaining the temperature until sufficient conversion is obtained. Depending on the embodiment, the temperature may be maintained for at least one hour. However, for full conversion additional time may be desirable, such as maintaining the temperature for two, three, four or more hours. Depending on the concentration of HCl used, the temperature may be maintained just below the boiling point of aqueous HCl and allows the HCl gas environment to be maintained by providing a pool of aqueous HCl in the enclosed environment. Alternative methods for achieving the conversion to (NH4)2UCl6 are also possible, such as passing HCl gas at a higher temperature through a kiln, moving bed, cyclone, fluidized bed reactor, or any other gas-solid contacting technologies. Fuming HCl (aqueous HCl at greater than 40% concentration) may also be used to generate HCl gas. In yet another embodiment, the mixture may be contacted with aqueous HCl in liquid, rather than gaseous, form under conditions that result in the (NH4)2UCl6. Yet another embodiment involves creating HCl gas for the first conversion operation 1604 by using calcium chloride (CaCl2) and aqueous HCl. In this embodiment, HCl gas is generated via the following reaction:CaCl2(s,anhydrous)+HCl(aq)=CalCl2.2H2O(s)+HCl(g) In this embodiment, the first conversion operation 1604 includes providing anhydrous CaCl2 pellets in the reaction environment and contacting the anhydrous CaCl2 with aqueous HCl. In an embodiment the contacting may be done by placing the CaCl2 pellets in a pool of HCl. In the first conversion operation 1604, a reactor vessel may be provided that can separately hold both the mixture and the pool of HCl with CaCl2 pellets so that only the HCl gas can contact the mixture. In an alternative embodiment, the liquid HCl may be circulated or flowed over a solid form CaCl2. Regardless of how the contacting is performed, as the water is removed from the aqueous HCl to hydrate the CaCl2, the concentration of the HCl in the liquid increases until HCl gas is released into the environment. This method for generating HCl gas can use a safer and more easily handled aqueous HCl concentration as the input and may be preferred over using other sources of HCl gas. This method for making HCl may be adapted for use with any of the methods described herein. Furthermore, aqueous HCl and NH4Cl having a modified amount of 37Cl isotope as the anion may be used to generate chloride fuel salts from the method 1600. As mentioned above, separation and collection of the 37Cl isotope is possible by several methods. This 37Cl can then be used to generate hydrogen chloride which, when combined with water, will generate modified aqueous HCl. There are many known methods for making hydrogen chloride and any suitable method maybe used, including combining Cl2 gas with H2 gas and reacting NaCl with H2SO4. Likewise, modified NH4Cl may also be generated using a source of 37Cl from any known method. The amount of modification of either of both the HCl and the NH4Cl may be controlled to achieve any desired ratio of 37Cl to total Cl in the final fuel salt, such as a final salt having a ratio of 37Cl to total Cl in the fuel salt of greater than 25%. After the first conversion operation 1604, a second conversion 1606 operation is performed in which the (NH4)2UCl6 is maintained under the appropriate conditions to convert it into UCl4 by the reaction:(NH4)2UCl6═UCl4+2NH4Cl In an embodiment, the second conversion 1606 includes removing the (NH4)2UCl6.2H2O from the HCl environment, heating it to a temperature sufficient for the conversion until the desired amount of the (NH4)2UCl6 has been converted to UCl4. Conversion is expected above 200° C., but higher temperatures may speed the reaction. In an embodiment, the (NH4)2UCl6. 2H2O may be heated to any temperature above 200° C. but below a temperature that melts the (NH4)2UCl6 or UCl4, such as from 200-500° C., from 250-350° C. or 400° C. Alternative embodiments are also possible, including embodiments that heat the (NH4)2UCl6 to temperatures that cause the generated UCl4 to melt during the conversion operation 1606. The embodiment of the method 1600 shown is suitable for producing UCl4 product in bulk. Furthermore, since UCl3 can be easily obtained from UCl4 via reduction, such as described above, the method 1600 can be easily used to create bulk quantities of UCl3 also, simply by adding an optional reduction operation 1608, as shown in FIG. 16. An embodiment of method 1600 was performed to verify the method. In the experiment, 2 grams of UO2 and 0.44 grams of NH4Cl (i.e., 10% excess NH4Cl) were ground together and placed in a reactor with aqueous HCl so that the environment had excess HCl gas. The reactor was heated to 100° C. and maintained at that temperature for four (4) hours. The resulting product was then removed and placed in a decomposition tube under vacuum and heated from 80 to 400° C. The creation of UCl4 was verified through x-ray diffraction. In the experiment, the HCl gas was produced using the CaCl2 method. The mixture of UO2 and NH4Cl was placed in an open-topped glass vessel and the vessel placed within the reactor. A pool of aqueous HCl was provided in the bottom of the reactor and pellets of CaCl2 were placed in contact with the aqueous HCl. An excess of HCl gas was produced by the hydration of the CaCl2 and this gas reacted with the solid mixture in the vessel. Uranium Chloride-Fluoride Fuel Manufacturing Processes FIG. 17 illustrates an embodiment of a method for manufacturing UCl3F. The method 1700 is based on the following reaction:3UCl4+UF4=4UCl3FIn the embodiment shown, the method 1700 starts with preparing amounts of UCl4 and UF4 in a precursor preparation operation 1702. The UCl4 and UF4 may be prepared by any methods described herein or known in the art. Solid UCl4 and UF4 are then combined in stoichiometric amounts in a combining operation 1704. In the embodiment shown, three parts UCl4 and one part UF4 are combined. The combining operation 1704 may be done in a mixer (e.g., a ball mill) in anticipation for the mixing operation 1706, discussed next, or may be done an intermediate vessel prior to transfer to a mixer. The combined UCl4 and UF4 is then mixed for a period of time to obtain a solid UCl3F mixture in a mixing operation 1706. The mixing operation 1706 may use any conventional solid mixing means such as grinding, crushing, or cutting with any suitable equipment such as a ball mill, rod mill, autgenous mill, SAG mill, pebble mill, roll grinder, stamp mill, etc. The mixing may or may not be performed at an elevated temperature or pressure. The time period of mixing may be a fixed time, based on the mixing conditions (e.g., at a high temperature), selected from 15 minutes to 5 days, such as, for example, a quarter of an hour, half an hour, three-quarters of an hour, an hour, two hours, four hours, six hours, eight hours, 12 hours or 24 hours. Alternatively, mixing may be performed for a time period sufficient for completion of the reaction, which time period is determined based on real-time or prior testing. In an alternative embodiment, the mixing operation 1706 may be performed with one or both uranium salts in a molten state, instead of a solid state. In yet another embodiment, the mixing operation may be performed in the reactor core of a reactor, such that the UCl3F salt is created within the reactor core. Any and all of the operations 1702-1706 may further be performed in an oxygen free environment, such as by mixing under argon or some other inert gas. An experiment was performed to validate the method 1700. As performed, 700 mg of UCl4 was mixed with 193 mg of UF4 in a ball mill for one hour under argon. After the one hour mixing time x-ray diffraction analysis of the precursors prior to mixing and the product of the experiment indicated that none of the precursor UCl4 or UF4 was present in the final product. Based on this, it is presumed that the reaction went to completion and the final product was UCl3F. Note that the method 1700 can be adapted to produce UCl2F2 and UClF3 by varying the stoichiometric amounts of the precursor salts. As discussed above, these salts may also have suitable properties for use as nuclear fuel, or as a constituent of a nuclear fuel salt, in a molten salt reactor. FIG. 18 illustrates an embodiment of another method for manufacturing UCl3F. This method 1800 generates UCl3F from UO2 based on the following reactions:2UO2(s)+3NH4Cl(s)+NH4HF2(s)+7HCl(g)=2[NH4]2UCl5F.2H2O(s)[NH4]2UCl5F.2H2O(s)=2NH4Cl+UCl3F+2H2OThis reaction is similar to that described with reference to FIG. 16. In the embodiment of the method 1800 shown, a mixture of solid UO2, NH4Cl, and NH4HF2 is created in a precursor preparation operation 1802. The solid mixture may be created using any conventional means such as grinding, crushing, or cutting with any suitable equipment such as a ball mill, rod mill, autgenous mill, SAG mill, pebble mill, roll grinder, stamp mill, etc. A first conversion operation 1804 is then performed, in which the solid mixture is exposed to HCl under the conditions appropriate to generate (NH4)2UCl5F by the reaction:2UO2(s)+3NH4Cl(s)+NH4HF2(s)+7HCl(g)=2[NH4]2UCl5F.2H2O(s)In an embodiment, the first conversion operation 1804 includes heating the solid mixture while exposing the mixture to an excess of HCl gas in an enclosed environment to 100° C. at 1 atm and maintaining the temperature until sufficient conversion is obtained. Depending on the embodiment, the temperature may be maintained for at least one hour. However, for full conversion additional time may be desirable, such as maintaining the temperature for two, three, four or more hours. Depending on the concentration of HCl used, the temperature may be maintained just below the boiling point of aqueous HCl and allows the HCl gas environment to be maintained by providing a pool of aqueous HCl in the enclosed environment. Alternative methods for achieving the conversion to (NH4)2UCl5F are also possible, such as passing HCl gas at a higher temperature through a kiln, moving bed, cyclone, fluidized bed reactor, or any other gas-solid contacting technologies. Fuming HCl (aqueous HCl at greater than 40% concentration) may also be used to generate HCl gas. In yet another embodiment, HCl gas for the first conversion operation 1804 may be created using calcium chloride (CaCl2) and aqueous HCl as has been previously described with reference to FIG. 16. After the first conversion operation 1804, a second conversion 1806 operation is performed in which the (NH4)2UCl5F is maintained under the appropriate conditions to convert it into UCl3F by the reaction:[NH4]2UCl5F.2H2O(s)=2NH4Cl+UCl3F+2H2OIn an embodiment, the second conversion 1806 includes removing the (NH4)2UCl5F.2H2O from the HCl environment, heating it to a temperature sufficient for the conversion until the desired amount of the (NH4)2UCl5F has been converted to UCl3F. Conversion is expected above 200° C., but higher temperatures may speed the reaction. In an embodiment, the (NH4)2UCl5F.2H2O may be heated to any temperature above 200° C. but below a temperature that melts the (NH4)2UCl5F or UCl3F, such as from 200-500° C., from 250-350° C. or 400° C. Alternative embodiments are also possible, including embodiments that heat the (NH4)2UCl5F to temperatures that cause the generated UCl3F to melt during the second conversion operation 1806. The method 1800 may also be used to generate modified 37Cl salts by using aqueous HCl and NH4Cl having a modified amount of 37Cl isotope as the anion, as has been discussed elsewhere. The amount of modification of either of both the HCl and the NH4Cl may be controlled to achieve any desired ratio of 37Cl to total Cl in the final fuel salt, such as a final salt having a ratio of 37Cl to total Cl in the fuel salt of greater than 25%. Fuel Salt Examples Various fuel salt embodiments were manufactured in the laboratory and tested to confirm the ternary phase diagram of FIG. 4. A number of UCl3 batches were prepared. One batch, which was typical of the preparations, was prepared as follows. A 1.895 g sample of uranium metal was washed with hexanes and treated with nitric acid to remove oxides. The uranium metal was placed in a quartz crucible, loaded into a tube furnace and held at 250° C. for 30 minutes under flowing H2, producing UH3. The UH3 was observed as a higher surface area product, morphologically different than the uranium metal starting material. The furnace temperature was increased to 350° C., the flowing gas switched to HCl, and held at temperature for 90 minutes, producing UCl3. The atmosphere was changed to H2 and the furnace brought to room temperature. The tube furnace was held under H2 atmosphere and transferred to an Ar glovebox. The UCl3 was characterized by x-ray diffraction, with a total recovered mass of 2.47 g. A number of UCl4 batches were also prepared. One batch, which was typical of the preparations, was prepared as follows. A 1.50 g sample of UO3 was added to a Schlenk flask and charged with Ar. Hexachloropropene was added under inert conditions in 10 times molar excess. The flask temperature was increased to 75° C. and held for 30 minutes. The temperature was increased to reflux around 165° C. and held for 3 hours. The product was brought to room temperature and washed with carbon tetrachloride, toluene, and hexane. After the hexane wash the product was dried and identified as UCl4 by x-ray diffraction. The procedure yielded 1.9 g of UCl4. The binary and ternary mixtures were created by melting appropriate amounts of the constituent compounds in a Mo crucible at 650° C. for 2 hours under an Ar atmosphere. A sample of 66NaCl-34UCl3 was prepared and characterized in the same manner using 3.761 g UCl3 and 1.239 g NaCl. A typical batch for the 71UCl4-17UCl3-12NaCl contained 0.6188 g of UCl4, 0.1331 g of UCl3 and 0.0158 g of NaCl. The three components were added to a Mo crucible and treated as described above. The mixed salt products were analyzed by differential scanning calorimetry. An embodiment of UCl3F was created using the synthesis reaction between UCl4 and UF4 as described above. In that experiment, 700 mg of UCl4 was mixed with 193 mg of UF4 in a ball mill for one hour under argon. After the one hour mixing time x-ray diffraction analysis of the precursors prior to mixing and the product of the experiment indicated that none of the precursor UCl4 or UF4 was present in the final product. Based on this, it is presumed that the reaction went to completion and the final product was UCl3F. The following fuel salts were created and their melting points determined as shown in Table 4. TABLE 4Fuel Salt EmbodimentsFuel SaltMelting Point (° C.)71UCl4—17UCl3—12NaCl491-51266NaCl—34UCl350817UCl3—40.5UCl4—42.5NaCl35147UCl4—53NaCl343UCl3FNAFuel Modification to Reduce Corrosion Management of molten salt corrosion may dictate the use of advanced materials, such as nickel and molybdenum alloys, for fuel salt-facing components, such as reflectors, PHX and vessel. In some embodiments, because of the design and operating conditions of suitable reactors components may only need to be clad or coated using these advanced materials, while the bulk of such components can be constructed from more traditional materials such as stainless steels and other materials with existing ASME code cases. Additionally, if components will be replaced on a regular basis, it is not necessary to provide exceptional clad performance or to demonstrate perfect coatings. In an embodiment, a compatible corrosion resistant cladding (CRC) will be utilized in conjunction with ASME Code compliant base material on all fuel salt-facing surfaces. ASME Section III, Division V “High Temperature Reactors” permits the use of CRC. Careful selection of materials, joining processes, and non-destructive examination allows for the construction of a robust composite metallic reactor enclosure with multiple layers of defense against corrosion, radiation damage, and high temperature service. In the embodiment, the CRC is the first barrier against uncontrolled release of radionuclides. It is comprised of corrosion resistant cladding on pressure vessel plate, piping, primary heat exchanger tubing and tube sheets and is designed for positive pressure. In an embodiment, the fuel salt is adapted to prevent or reduce corrosion by providing one or more chloride salts that correspond to the salts that would have been created through corrosion. By providing such a salt as one of the (or the only) additional, non-fissile chloride salt, this will reduce or prevent the corrosion of the salt-facing mechanical components. FIG. 12 illustrates an embodiment of a method of reducing corrosion in a nuclear reactor using a molten nuclear fuel. The method 1200 is suitable for any fuel salt anion including Cl, F, or combinations such as Cl3F, Cl2F, Cl2F2, etc. In the embodiment shown, the method 1200 starts with an identification operation 1202 that determines what material or materials will be salt-facing in the reactor. For example, as discussed above it is anticipated that nickel and molybdenum alloys may be used for various salt-facing components. The identification operation 1202 is then followed by a determination of the cation or cations in the identified material that is most likely to corrode in an analysis operation 1204. The analysis operation 1204 may be a purely theoretical analysis, for example, based on a comparison of the relative free energies of salt formation for each of the elements in the material. Alternatively or in addition, the analysis operation 1204 may include corrosion testing using different representative salts in order to experimentally identify the likely corrosion chemistry. After the cation or cations subject to salt corrosion have been determined, a fuel salt may be generated specifically for that reactor that includes in the nuclear fuel salt a corrosion inhibiting salt consisting of the salt anion (e.g., chloride in a MCFR) and the material cation (e.g., Mo, if the analysis operation 1204 determines Mo corrosion is an issue with that particular alloy). The amount of the corrosion inhibiting salt may be determined experimentally or may be selected based on the amount of salt necessary to eliminate the corrosion reaction by bringing amount of the corrosion inhibiting salt in the fuel salt to the amount necessary to achieve equilibrium under the reactor's operational conditions (pressure, temperature, etc.). Alternatively, the maximum amount of the corrosion inhibiting salt in the nuclear fuel that can be solubilized in the nuclear fuel. For example, in an embodiment of the method 1200 it may be determined in the analysis operation 1204 that Cr corrosion will likely occur. In response, a corrosion resistant fuel may be created that includes at least some CrCl2. FIG. 13 lists some alloys of potential applicability. The figure lists the alloy, the major element or elements (>1% by mass) of each alloy, and the minor elements (<1% by mass) of each alloy. Experiments were performed on some of the alloys in FIG. 13 using both 71UCl4-17UCl3-12NaCl and 66NaCl-34UCl3 fuel salt embodiments under representative conditions. The alloys tested included 316SS stainless steel. In these experiments, a coupon of alloy was inserted into a volume of the fuel salt and the conditions were maintained at 650° C. for 100 hours. The coupons were then inspected using energy dispersive spectroscopy. Inspection of the stainless steel showed significant depletion of the chromium and measurable depletion of the Fe from the alloy coupon. This validated the results of theoretical analysis based on the relative free energies of the cations in the alloy (see below) that indicated that Cr would be more corroded by Cl salt, Fe relatively less, and Ni and Mo even less.ΔHCrCl2<ΔHCrCl3<ΔHFeCl2<ΔHNiCl2<ΔHMoCl2 In response to this analysis, a corrosion inhibiting salt could include one or more of CrCl2, CrCl3 and FeCl3 for the 316SS alloy. Some or all of these corrosion inhibiting salts could be added to a chloride fuel salt to reduce or eliminate the corrosion of this alloy.Fuel Monitoring During operation, the fuel salt in a molten salt reactor may be monitored. This monitoring may be done in order to determine when sufficient breeding has occurred so that some of the fuel may be removed and replaced with new fuel in order to keep the reactivity down. Such monitoring may take many forms but includes monitoring at least one concentration of a molecule in the molten salt that is indicative of the overall quality of the salt. In response to the results of the monitoring, e.g., a result indicating sufficient breeding has occurred, some action may be taken such as changing an operational parameter or replacing some fuel salt with new fuel salt. Monitoring may be performed using any type of suitable speciation method or equipment including spectroscopic methods or tools, now known or later developed. For example, in an embodiment, the monitoring is performed in real-time using Raman spectroscopy, or laser ablation methods. Raman spectroscopy provides information from molecular vibrations that can be used for sample identification and quantitation. The technique involves shining a monochromatic light source (i.e. laser) on a sample and detecting the scattered light. Some amount of fuel may be removed from the reactor core, such as in a side stream, and passed through a monitoring cell that includes a ‘window’ through with the spectroscopy can be performed. Examples of Raman windows materials are fused quartz, fused silica, sapphire, diamond, and some glasses. Laser ablation methods excited the compound to high energy states. The excited material can be evaluated with a mass spectrometer or optically to determine element composition and possibly molecular species. Any material may be used as long as it can meet the operational parameters of the reactor and monitoring system. In some embodiments, the removed fuel from the core for monitoring may be all of or a portion of a side stream of fuel removed for fuel polishing/processing as described further below, a side stream for control purposes to be replaced with fertile fuel, and/or a side stream off of the primary coolant loop 110 described above with respect to FIG. 1A. Other sampling configurations than a side-stream sampling configuration may also be used. For example, in an embodiment a window may be provided somewhere in the reactor core, through which the speciation equipment (e.g., Raman spectrograph or ablation system) may transmit light to the fuel, or the headspace, if any, above the fuel. Alternatively, the speciation equipment may be a remote instrument that is wirelessly- or wire-connected to a monitoring system outside of the reactor and that is capable of being inserted into the fuel salt or a fuel salt stream, such as through a wall of the reactor core or piping. In another embodiment, the spectrograph may be included within a heat exchanger apparatus or other component physically within the reactor core in order to sample fuel salt directly. In yet another embodiment, the spectrograph or ablation system may be an ancillary component 127 as described with reference to FIG. 1A. In yet another embodiment that is not real-time, samples may be periodically removed from the reactor core and analyzed. Such samples may then be returned or collected for later use. For example, in an embodiment some amount of fuel salt is replaced in an operating MCFR on a schedule and the removed fuel salt is analyzed by laser ablation, optical methods, or with a Raman probe. The results of this analysis are then used to modify one or more parameters such as to modify the schedule for replacing fuel salt. Examples of other operation parameters that may be adjusted include reactor core temperature, fuel salt replacement quality, a position of a displacement element, a reactivity of the fuel salt, and a feed rate of an additive to the reactor core. FIG. 14 illustrates a method of operating a molten salt nuclear reactor. In the embodiment shown, the method 1400 starts with maintaining breed-and-burn behavior in molten salt in a reactor core of the nuclear reactor in operation 1402. During operation, at least some of the molten salt is analyzed in a real-time analysis operation 1404. In an embodiment, the analysis is done using speciation methods such as a Raman spectroscopy or laser ablation methods to determine at least one concentration of a molecule in the molten salt. Alternatively, the speciation may be done to determine most if not all of the molecules in the fuel and their relative amounts allowing for a complete or near-complete chemical makeup of the fuel salt at that location to be known. In yet another embodiment, radiation detectors such as gamma detectors may be used to monitor the energy or activity of the molten salt, and determinations of the partial or complete chemical makeup of the fuel salt at that location may be made based on the salt makeup and measurements. Based on the resulting knowledge of the chemical makeup of the fuel salt, an adjustment operation 1406 may be performed if the chemical makeup or a particular concentration exceeds some predetermined threshold. The adjustment may include adjusting one or more operational parameter of the nuclear reactor or performing specific tasks such as fuel replacement. Raman spectroscopy is but one of the speciation techniques that could be used to monitor fuel salt quality and/or other safety or design considerations, e.g., accumulation of fission products, viscosity, etc. Other techniques include absorbance spectroscopy, laser ablation spectroscopy, laser induced breakdown spectroscopy, infrared (IR) spectroscopy, and electrochemistry to determine the relative concentrations of different salt constituents (e.g., UCl3, UCl4 and NaCl). As discussed above, any technique, now known or later developed, may be used for monitoring. Freeze Plugs Another aspect of molten fuel salt reactors includes the possible use of frozen material plugs for different purposes. A frozen material plug, referred to herein as a freeze plug, is a volume of material that at intended operational conditions is solid, non-reactive with the fuel salt, and has a sufficiently strong solid structure that it can be used to prevent the movement of fuel salt within the reactor but that also, upon reaching a desired activation temperature, melts to allow mixing with and movement of the fuel salt. Freeze plugs may be used for many different purposes and, in some embodiments, for multiple purposes at one time. For example, in a simple embodiment a freeze plug may be used to prevent fuel salt from flowing out of the reactor core into a dump tank when at operational temperatures, but that melts if the reactor core temperature exceeds that plug's activation temperature, thereby allowing the fuel salt to exit into the dump tank. This may be achieved by locating the dump tank below the reactor core so that the fuel salt can flow by gravity or by maintaining the reactor core and the dump tank at different pressures so that, upon melting of the freeze plug, molten fuel salt flows under pressure into the dump tank. In some cases, the freeze plugs may be detectable within the fuel upon melting. For example, the freeze plug may be made of some material that is a neutron poison so that if the reactor core exceeds the activation temperature the poison material melts and is subsequently distributed throughout the reactor core reducing reactivity. In this embodiment, the freeze plug is the neutron poison. Achieving a similar function, in another embodiment the freeze plug is used to prevent a quantity of neutron poison held in a vessel separate from the reactor core from mixing with the fuel salt. Upon reaching the activation temperature, the freeze plug melts and releases the poison into the reactor. As with the dump tank embodiments, the vessel of poison may be located above the reactor core so that it flows under gravity into the reactor core or alternatively, may be maintained under pressure so that the poison is forced into the reactor core. In this manner, activation or melting of the freeze plug is highly detectable in the neutronic reactions of the reactor core. In additional or alternative embodiments, the freeze plug may contain or separate one or more elements that are detectable in other suitable manners, such as by the fuel monitoring system (e.g., Ramen Spectroscopy), other sensors within the reactor, etc. Many other configurations of safety-related freeze plugs are possible. Freeze plugs may be passively maintained by providing a freeze plug material that has the appropriate melting point tailored to the desired activation temperature. In an alternative embodiment, freeze plugs may be actively maintained by providing an actively cooled component, such as a cooling jacket, around the location of freeze plug. Actively maintained freeze plugs may be used, for example, to allow for operator control of activation (through control of the cooling) or as a safety measure that activates upon loss of external power or control. Active control also allows for the use of fuel salt as a freeze plug, simplifying the use of freeze plugs in the operation of the reactor. Suitable freeze plug materials include salts that are miscible in the fuel salt and that have the appropriate melting temperature higher than that of the reactor's operational temperature. In some cases, it may be appropriate to include a chemical barrier between the freeze plug and fuel salt to reduce the occurrence of inadvertent dissolution of the plug. For example, in an embodiment of an MCFR using a ternary fuel salt such as those described above, a suitable freeze plug may be any chloride salt, which has a melting point higher than that of the ternary salt embodiments. For moderating purposes, an embodiment of a freeze plug that acts as a neutron poison includes freeze plugs made with 35Cl. As discussed above, 35Cl is a neutron moderator and absorber and salts of 35Cl when dissolved into the fuel salt will reduce the salt's reactivity. Other potential freeze plugs suitable for use in an MCFR include chloride salts of fission products with high absorption cross sections such as 133Cs, 101Ru, 103Tc and 105Pd. In some embodiments, the freeze plug material may not be a fuel salt or even a salt with the same anion as the fuel salt. Suitable freeze plug materials include those materials with a melting temperature that is targeted for the safety melting point for an action to occur and likely not react negatively with the fuel salt. Modified fuel salt with a higher melting temperature is just one example of this. Thus, a freeze plug potentially may be made of any material. In yet another embodiment, the freeze plug material may be a neutron reflective material such that, upon reaching the activation temperature, the reflective freeze plug melts and provides less reflection of neutrons, thereby changing the overall reactivity of the reactor. In this embodiment, the freeze plug may further expose, release or uncover a neutron poison upon melting. For example, a reflective freeze plug may cover a neutron absorber and thus operate as a reflector component that self-destructs upon reaching an activation temperature. Ongoing Fuel Polishing In an embodiment, during normal operations MCFR fuel salt only receives minor treatments other than periodic replacement of an amount of nuclear fuel salt with fresh fuel salt. In some cases, the removed fissile fuel will be replaced with fertile fuel salts. Some possible minor treatments for fuel polishing include mechanical filtering of fission products such as the noble metals and minimal removal of noble gases. In an embodiment, the treatment includes removal of noble gases that are created during the ongoing nuclear reaction. Such gases will include various isotopes of Kr, Xe and Ar. These gases may be removed by sparging of the fuel salts. Sparging will also have the effect of removing any other gaseous volatile fission products that may be created. In an embodiment, fissile materials are not separated in any portion of the MCFR fuel cycle. Rather, bred plutonium is mixed in operation with fertile uranium and created fission products, including lanthanides, which are chemically similar and expected to be soluble in the fuel salt embodiments. In this manner, fuel polishing may be simplified in MCFR over typical fuel processing of prior fluoride molten salt reactors since the lanthanides in the MCFR will not need to be removed. Fuel polishing may further include mechanical filtering to remove any precipitates that may be generated by the ongoing nuclear reaction and/or operation of fluid flow and moving components. Both filtering and sparging may be performed by conventional means including those presented above with reference to FIG. 1A. Fuel polishing may further include mechanical filtering to remove any precipitates that may be generated by the ongoing nuclear reaction and/or operation of fluid flow and moving components. Both filtering and sparging may be performed by conventional means including those presented above with reference to FIG. 1A. FIG. 19 illustrates an embodiment of a polishing system for fuel polishing that utilizes a drain tank 1904. In an embodiment, the system 1900 is designed to remove most, if not all, insoluble fission products, corrosion products, and other compounds that have the potential to alter the fuel salt stoichiometry beyond design specifications. The system 1900 may also clean the fuel salt to acceptable specifications under normal and off-design operation. In the system 1900 illustrated, gas phase contaminants may evolve into the void space above the reactor core. These contaminants could contain fission products, noble gases, UCl4, etc. The off-gas system includes the equipment for safely handling this off gas stream and recovering the UCl4. The system 1900 includes equipment to dissipate the heat, collect and store/dispose of stable and long-lived gases, recovery of the UCl4, and recompression/recycling of the inert gases. The system 1900 further may have the ability to reduce the concentration of corrosion elements such as oxygen and sulfur. In addition, the system 1900 may remove dissolved noble gases, such as 135Xe. In the embodiment shown, the system is comprised of several different unit operations to facilitate the cleanup of the fuel salt. These include: Filtration of insoluble fission products; helium bubble generation to aid in the removal of noble gas fission products from the fuel salt prior to reinsertion in the reactor core; degassing of the helium bubbles/noble gases from the molten salt prior to reinsertion in the reactor core; passing the degassed helium bubbles/noble gases through a long delay chemical trap system where the isotopes will decay to insignificant levels; and recycling of the helium. In an embodiment, any vent gases from the reactor system would be vented to this system 1900. These gases would pass through a scrubber where it would be contacted with cooled fuel salt to remove any UCl4 in the gas stream. In the embodiment shown, the drain tank 1904 is located at a level lower than the fuel salt level 1912 in the reactor core 1902 to allow molten fuel salt from the reactor core 1902 to flow under gravity into the drain tank 1904 for polishing. The fuel 1906 may be removed from one or more locations in the reactor core by gravity flow or siphon. The transfer of gas between the reactor core head space 1920 and the drain tank headspace 1921 may be controlled to maintain the desired level 1916 of fuel salt in the drain tank 1904. In an embodiment, to preserve the integrity of the reactor core, a dip tube 1910 is provided from the top of the reactor core 1902 to the depth within the fuel salt 1906 from which removal is desired. The flow rate may be controlled by valves or by selection of discharge pipe diameter and pressure differential between the reactor core 1902 and drain tank 1904. The treatment system 1900 can be operated in continuous or batch fashion. The system may be sized to treat any desired throughput, such as for example 1% per minute or 0.1% per minute of the total fuel salt 1906 in the system. In an embodiment, the drain tank 1904 may be maintained at the same operating temperature and pressure as the reactor core. In an alternative embodiment, drain tank and treated sidestream of fuel salt may be maintained under different conditions selected to improve treatment or handling characteristics of the fuel salt. For example, in an embodiment the fuel salt 1906 in the drain tank 1904 may be maintained at a temperature from 800-900° C., such as 850° C. A heater exchanger 1908 is illustrated in the drain tank 1904 for temperature control, however any suitable technology may be used such as heated jacket around the drain tank. In yet another embodiment, the relative operating conditions of the reactor core 1902 and the drain tank 1904 may allow treatment to occur without actively heating the drain tank 1904, in which case the tank 1904 may only be insulated rather than actively heated. In some embodiments, the number of valves may be reduced or eliminated to reduce the amount of maintenance needed. For example, in an embodiment the system is operated in batch fashion and valves are eliminated. The drain tank 1904 is filled from and discharged back into the reactor core 1902 by adjusting the pressure in the drain tank 1904 relative to the reactor core 1902, e.g., by pumping gas into the drain tank 1904 or by physically raising/lowering the drain tank 1904 relative to the fuel salt level 1912 in the reactor core 1902. In an alternative embodiment, one or more pumps 1914, such as the VTP™ variable speed molten salt pump by Flowserve Corporation, may be provided to transfer treated fuel salt 1906 back to the reactor core 1902. In an embodiment, it would be undesirable to have level control valves in the return line, so the level 1916 of salt 1906 in the drain tank 1904 could be controlled by the speed of the pump 1914. The level 1916 could be measured by either a non-intrusive nuclear level detector, by thermocouples in the drain tank or by any suitable level sensing technique. The system 1900 includes three different fuel salt treatment components that can receive fuel salt from the drain tank 1904: a degassing system 1924 that includes a helium contactor 1926 and a separation vessel 1928; a filtration system illustrated as filter 1930; and a UCl4 condenser 1932. In the embodiment illustrated, the degassing system 1924 and filtration system 1930 are connected serially so that fuel salt exiting the degassing system flows through the filtration system and the UCl4 condenser 1932 is a parallel treatment component. However, in alternative embodiments the three components may be connected in any configuration either serially or in parallel. Each component 1924, 1930, 1932 will be discussed in greater detail below. In the degassing system 1924 illustrated, fuel salt 1906 from the drain tank 1904 is transferred into a degassing vessel that acts as a helium contactor 1926 where helium would be added in the presence of strong agitation. In an embodiment, a rotary degasser may be used as the helium contactor 1926. As a result of the contacting, the 135Xe and other noble gases diffuse from the fuel salt 1906 to the helium gas. The helium gas, now a He mixture with 135Xe and other noble gases, would separate from the fuel salt 1906 and vent to the off gas treatment system 1922, either directly or indirectly by being routed first through the headspace 1921 in the drain tank 1904. The fuel salt 1906 from the helium contactor 1926 is transferred, for example via overflow by gravity or by pumping, to a separation vessel 1928 to provide more residence time for the helium to separate from the fuel salt 1906. In an embodiment, the helium contactor 1926 and separation vessel 1928 are located at a higher elevation than the drain tank to provide the pressure drop necessary for the fuel salt to “overflow” from the helium contactor, through the separation tank and to the filter 1930 without a second pump. Alternative embodiments may also be used in which pumping or differential pressure transfer may be used. In yet another embodiment, the separation vessel 1928 may be omitted in favor of a larger helium contactor 1926 or a series of parallel contactors 1926 that are independently and alternately operated in a batch mode to provide sufficient helium contacting and separation time. In the embodiment shown, the degassing system 1924 may be operated continuously such that a constant flow of fuel salt is maintained through both vessels and out the bottom of each 1926, 1928. On benefit of the gravity flow and draining each vessel from the bottom is to avoid the accumulation of solids in the bottom of either vessel. Accumulated solids would be a radioactive waste that would have to be removed and disposed. The separation vessel 1928 drains into the filter system 1930, which removes any particulate prior to returning the fuel salt 1906 to the drain tank 1904. In an embodiment, some treatment chemicals may be added to the fuel salt prior to its introduction into the degassing system 1924 or the filter system 1930 or both. The purpose of such treatment chemicals would be to chemically modify contaminants in the fuel salt in order to more efficiently remove the contaminants by the degassing system 1924 or the filter system 1930. For example, injecting liquid NaAlCl4 may assist in oxide removal. In an alternative embodiment, the degassing system 1924 may be incorporated into the reactor core 1902. In this embodiment, helium gas is delivered into the reactor core 1902. While some gas will leave the fuel salt and collect in the headspace 1920 where it can be removed and treated by the off gas system 1922 as described above (with or without being passed through the drain tank 1904), some helium will cause cavitation in the circulation pumps. In this embodiment, the helium may be collected from the pumps and likewise removed and treated by the off gas system 1922 as described above. In an embodiment, the filter system 1930 may be directly connected to the top of the drain tank 1904. Any suitable type of filter may be used. For example, in an embodiment the filtration system may include a tube sheet supporting a number of individual tube filter elements inside of a filter vessel 1930. In an embodiment, filter elements would not be cleaned in service. Solids will accumulate on the filter material surface over time until the filter vessel 1930 is taken out of service and the filter elements either discarded as waste or regenerated. The filter vessels 1930 may be sized for any desired nominal lifetime based on the design throughput of the system 1900. In an embodiment, the filter elements are made from either sintered molybdenum powder or fiber to reduce corrosion. The initial pressure drop of the filter system will be very low. The filter elements could be installed “upside down”, that is with the tube sheet at the bottom of the vessel 1930 and the filter elements extending vertically upwards above the tube sheet, so that the vessel would continually drain into the tank 1904. The filter inlet may be located as close to the tube sheet as possible to minimize the holdup of molten salt in the filter vessel. As particulate accumulates on the filter surface and the pressure drop increases, the liquid level will rise in the filter vessel. The UCl4 condenser 1932 is designed condense gaseous UCl4 and return it to the drain tank 1906. In the embodiment illustrated, the UCl4 condenser 1932 is connected so that it receives and treats gas from the filter system 1930 and the drain tank 1904. In an alternative embodiment, the UCl4 condenser 1932 may be connected to other gas streams from other components such as the reactor core 1902. In an embodiment, the condenser 1932 is a countercurrent contacting heat exchanger using cooled fuel salt 1906 from the drain tank 1904 as the coolant. The melting point of pure UCl4 is 590° C. and the boiling point is 791° C., so a portion of the fuel salt 1906 from the drain tank 1904 may be cooled, using any conventional heat exchanger such as a shell and tube heat exchanger 1934, illustrated, to below the boiling point of UCl4, such as 700° C., and flowed through nickel or molybdenum structured packing countercurrent to the vent gases. The condenser 1932 may be a packed column of containing random nickel and/or molybdenum packing elements. This would condense any UCl4 in the vent gas. Because the exchanger is a contacting vessel, condensed UCl4 would combine with the cooled fuel salt and be returned to the drain tank 1904. The gaseous output of the condenser 1932 may be cooled prior to delivery to the off gas treatment system 1922. As shown in FIG. 19, the discharge flow from the drain tank 1904 may be transferred to the reactor core 1902, the degassing system 1926, or to the UCl4 condenser 1932 as the coolant. These flows may be actively controlled by valving (not shown) or restricting orifices may be placed in the various lines to balance the fuel salt flows and avoid the requirement for valves. Sizing of these restricting orifices will depend on the actual routing of the piping and ensuing hydraulic calculations. The off gas treatment system 1922 receives fission product gases and holds them for a sufficient time to allow some radioisotopes to decay. In the embodiment shown, vent gases 1918 are removed from the void space 1920 above the fuel salt level 1912 in the reactor core 1902 and flow into the drain tank 1904. The gas flow leaving from the drain tank 1904 would flow, either directly or as illustrated in FIG. 19 indirectly via the UCl4 condenser 1928, through an off gas treatment system 1922. In addition, in the embodiment illustrated the off gas treatment system 1922 receives gas directly from the degassing system 1924. In an embodiment, the flowrate of gases through the entire system including the reactor core 1902, drain tank 1904 and the off gas treatment system 1922 are controlled by valving and instrumentation located at the exit of the off gas treatment system 1922 where the temperature is cool and there is little to no radiation. This embodiment avoids the need for a compressor/blower between the reactor and the drain tank. It is anticipated that the total yield of tritium will flow out through the off gas system 1922. FIG. 20 illustrates an embodiment of an off gas treatment system 2000 suitable for use in treating gaseous fission products produced by a molten salt reactor, for example as the off gas treatment system 1922 in FIG. 19. The system is designed to receive the gaseous fission products in a carrier gas such as helium although other gases are possible. In the embodiment shown, the flow through the off-gas system 200 primarily consists of two recycle loops, a short delay holdup loop 2002 and a long delay holdup loop 2004. Inlet gas to be treated may first be cooled and filtered before entering the recycle loops as illustrated in FIG. 20 by cooler 2006 and filter 2008. In an embodiment, the filter 2008 is designed to remove any gas borne particulate, metals, salts, or fission products that may be in the gas. Based on the molten salt chemistry, the primary constituents of the filtered inlet gas will be Kr, Xe and tritium. The short delay holdup loop 2002 includes one or more vessels containing activated carbon. In the embodiment shown, the short delay holdup loop 2002 has three parallel activated carbon vessels 2006, each nominally sized to handle 50% of the anticipated Xe load. In an embodiment, the short delay holdup loop 2002 is a holdup loop designed to retain the received gases for a period sufficient to allow the 135Xe to decay to less than 5% of the inlet concentration. This period may be actively controlled and determined by monitoring the inlet and outlet concentrations of 135Xe or the loop 2002 may be designed with a fixed residence time based on the half-life of 135Xe, such as for example from 45 to 49 hours or 40 to 60 hours. The activated carbon vessels 2006 may be maintained in a shielded enclosure or may be individually shielded vessels to attenuate any radiation escaping the system 2000. A vessel cooling system 2008 may also be provided, such as a thermal bath of water or other heat transfer fluid in which the vessels 2006 are immersed, to mitigate the decay heat. In an embodiment, waste heat from the vessels 2006 may be used to generate low pressure steam, thus recovering energy from the cooling system 2008. Gas exiting the short delay holdup loop 2002 may be transferred to the long delay holdup loop 2004, may be transferred to a carrier gas recovery system or both. In the embodiment shown, gas exiting the short delay holdup loop 2002 is divided into two streams, one stream going to the long delay holdup loop 2004 and the other stream to a helium gas recovery system 2010. In an embodiment, some flow of gas greater than 50% of the total outflow of the short delay holdup loop 2002 (e.g., 70-90%) is passed through one or more chemical traps 2012 and radiation alarms 2014 before entering a surge tank 2016 at the inlet of a carrier gas compressor 2018. The helium is compressed and then stored in the accumulator tank 2020. In an embodiment, helium from this accumulator tank 2020 is metered and recycled for use as new carrier gas, such as by being fed into degassing system 1924. Any outlet gas from short delay holdup loop 2002 not treated by the carrier gas recovery system 2010 will be transferred to the long delay holdup loop 2004. The long delay holdup loop 2004 is designed to retain the Kr and Xe long enough for the radioisotope concentration to drop to an acceptable discharge threshold. In an embodiment, similar to the short delay holdup loop 2002, the long delay holdup loop 2004 includes one or more vessels containing activated carbon. In the embodiment shown, the long delay holdup loop 2004 has three parallel activated carbon vessels 2006, each nominally sized to handle 50% of the anticipated Xe load for the specified period, in this case 90 days but which may be from 50-150 days depending on the desired discharge threshold. The activated carbon vessels 2006 may be maintained in a shielded enclosure or may be individually shielded vessels to attenuate any radiation escaping the system 2000. A vessel cooling system 2008 may also be provided, as described above. Exiting the long term Xe holdup system, the gas may be transferred through a preheater 2022 which raises the gas temperature to 800° C. or higher. The gas may then be passed through a catalyst vessel 2024 where the tritium is oxidized with air. The gas then flows through a water cooled aftercooler 2026 or set of aftercoolers 2026, as shown, that reduces the temperature to reduce the heat load on the final charcoal packed absorber 2028. In an embodiment, the absorber 2028 is designed to operate at to −20° C. The tritium, Kr and Xe are retained on the charcoal while the helium gas passes thorough the bed. After leaving the refrigerated absorber, the helium is compressed and can be recycled to the reactor purge system for pump seals, etc. In the embodiment shown, there are three refrigerated absorbers 2028 sized for 50% of the anticipated load with two of the three in service at all times. At any given time, the out-of-service absorber 2028 will be regenerated by heating the absorber electrically and flowing a small heated helium stream through the absorber in the reverse direction. This regenerated gas stream containing Kr, Xe, and 3H2O would flow into a liquid nitrogen cooled receiver cylinder 2030 for permanent storage. FIG. 21 illustrates an embodiment of a method for polishing fuel salt based on the systems described in FIGS. 19 and 20. In the embodiment shown, the method 2100 starts with transferring irradiated fuel salt from the operating reactor core 1902 to the drain tank 1904 in a transferring operation 2102. The fuel salt is then degassed in a degassing operation 2104 in which a carrier gas, such as helium, is contacted with the irradiated fuel salt, thereby removing gaseous fission products from the fuel salt. In an embodiment, the degassing operation 2104 may include contacting the fuel salt with the carrier gas in a contacting vessel then transferring the fuel salt to a second vessel for some residence time to allow additional time for the separation to occur. This operation 2014 creates a carrier/fission product gas mixture and a degassed fuel salt having a reduced amount of gaseous fission products relative to the irradiated fuel salt. After the degassing operation 2104, the degassed fuel salt may be filtered in a filtration operation 2106. In an embodiment of the filtration operation 2106, degassed fuel salt passes through a filter 1930 under gravity and the filtered fuel salt effluent drains into the drain tank 1904. As presumably any solids in the fuel salt at operational temperature are some form of contaminant (either a fission product solid, corrosion product, or some other contaminant), any filtered solids are unwanted and are removed and disposed of in this operation 2106. The polishing method 2100 further includes treating the carrier/fission product gas mixture generated by the degassing operation 2104 in a carrier gas treatment and recovery operation 2108. This operation 2108 includes collecting the carrier gas/fission product mixture from the system and transferring it to an off gas treatment system, such as the system 1922 described above. The carrier gas treatment and recovery operation 2108 may include storing the carrier gas/fission product mixture for a first period of time, then recovering the carrier gas from the mixture by passing the carrier gas through a separator, carbon filter, ion exchanger, or other chemical trap that removes Kr and Xe from the carrier gas and otherwise cleans the carrier gas sufficiently to allow it to be reused. The polishing method 2100 may further include collecting gaseous UCl4 that evaporates from the fuel salt and re-condensing it in a UCl4 condensation operation 2110. Recovered UCl4 condensate is returned to the fuel salt by dissolving it into a fuel salt stream and returning the stream, which may be considered a high concentration UCl4 fuel salt, to the drain tank or reactor core. The method 2100 includes returning the filtered, degassed fuel salt to the reactor core. In an embodiment for the system 1900 in FIG. 19, the method 2100 is continuously operated on a sidestream taken from the reactor core 1902. In this embodiment the drain tank 1904 is continuously receiving both irradiated fuel salt from the reactor core 1902 and filtered fuel salt from the filtration system 1930. In addition, fuel salt with condensed UCl4 is also received from the UCl4 condenser. Simultaneously, polished fuel salt from the drain tank is being transferred to the reactor core. In alternative embodiments, the operations of the method 2100 described above may be performed concurrently as continuous or batch processes. In addition, the various operations may be performed serially as continuous or batch processes. Fuel Salt Post-Processing Fuel salts removed from an operational reactor will include fission products in addition to the fuel salt constituents described herein. While some fission products may be easily removed by sparging, settling or differential precipitation, others, particularly the lanthanides as described above, may be difficult to remove. Note that such used fuel salt purification may not be necessary in the fast spectrum of the chloride fuel salts, as used fuel salt may be suitable for use ‘as is’ as startup material for another molten salt reactor. However, if purification is desired, a fission product removal system may be utilized. A removal system may be configured to remove one or more lanthanides from the nuclear fuel salt. A fission product removal system may include one or more plasma mass filters. By way of non-limiting example, the one or more plasma mass filters may include an Archimedes-type plasma mass filter. The use of an Archimedes-type plasma mass filter is described by R. Freeman et al. in “Archimedes Plasma Mass Filter,” AIP Conf. Proc. 694, 403 (2003), which is incorporated herein by reference in the entirety. In another embodiment, an Archimedes filter plant (AFP) may act to remove one or more lanthanides from fuel salt from one or more reactors. In one embodiment, the AFP may include two plasma mass filters. By way of non-limiting example, each of the two plasma mass filters is capable of processing approximately a ton of fuel salt per day. In another embodiment, the first plasma filter is tuned so as to separate out the heavy elements from the fuel salt, with the second filter being tuned to separate the salt constituents from the fission products. In this configuration, the AFP could support a fleet of approximately 100-200 molten salt nuclear reactors (e.g., molten chloride salt fast reactors). In another embodiment, the fleet could utilize Archimedes-type filtering in a batch-type process. By way of non-limiting example, in a batch-type process, each reactor may send a portion (e.g., 10-20%) of its salt to the AFP every 1-3 years. Further, the salt may either be returned to the original reactor, swapped with the salt from another reactor, or replaced with depleted uranium loaded salt in the original reactor. The lanthanide-cleaned salts may be used to start up additional molten salt nuclear reactors without the need for ongoing enrichment, as discussed above. It is noted that the reactor 100 of the present disclosure is not limited to the Archimedes-type filter described above, which is provided merely for illustrative purposes. It is recognized herein that the separation requirement of the reactor 100 of the present disclosure may be significantly less than system typically used in the context of an Archimedes-type system. For example, the reactor 100 of the present disclosure may only require a separation efficiency required of approximately 0.99 or 0.9. As such, a significantly simplified plasma mass filter design may be used in the context of reactor 100 of the present disclosure. In another embodiment, the fission product removal system includes a significantly smaller plasma mass filter capable of cleaning 30-50 kg of salt each day. By way of a non-limiting example, a small bypass flow (˜10-8 of the flow) may be sent to the filter for cleaning and immediately sent back to the core without the need for off-site transport. It is noted herein that, while small plasma mass filters may lose some economy of scale, they are affordable and significantly less expensive than procurement of fresh fuel that has been enriched in fissile material. Anti-Proliferation Technologies Since molten nuclear fuel salt may be removed from the reactor 100, it is desirable to provide anti-proliferation safeguards to the molten fuel salt 108 of the present disclosure. In one embodiment, the molten fuel salt 108 is pre-loaded or initially created with one or more materials, such as lanthanides or other elements, that can be difficult to separate from the fuel salt but improve the proliferation resistance and which serve as a neutron absorber in the molten fuel salt 108. This diminishes the capacity of the fuel salt for use in weapons applications if it were to be intercepted prior to its use as a nuclear fuel in a molten salt reactor but does not substantially affect the criticality of the MCFR due to its fast spectrum. The addition of lanthanides also make the fuel salt more dangerous to handle, thereby also reducing its attractiveness for use in weapons applications. One method of determining the attractiveness of a material for weapons use is referred to as the Figure of Merit (FOM). The FOM is a calculation that takes into account the mass of a material (or materials), its dose and its decay heat. One equation for the FOM is as follows: F ⁢ ⁢ O ⁢ ⁢ M = 1 - log 10 ( M 800 + Mh 4500 + M 50 ⁡ [ D 500 ] 1 log 10 2 ) where M is the bare critical mass in kg of the metal component of a compound (i.e., does not include the weight contribution of oxides, chlorides, other anions, etc.), h is the heat content or decay heat in W/kg, and D is the dose of 0.2*M at 1 m from the surface in rad/hr. For non-proliferation purposes, an FOM of <1.0 is deemed to be unattractive for weapons purposes. Thus, in an embodiment, lanthanides are added to the fuel salt to the extent necessary to obtain an FOM of <1.0. In one embodiment, when pre-loaded into a molten chloride-based fuel, the one or more pre-loaded lanthanides act to form one or more lanthanide trichlorides. It is noted that these compounds are similar, in at least a chemical sense, to PuCl3, which is present in the molten fuel (e.g., Pu-239 is formed during enrichment and may form PuCl3). The presence of the one or more lanthanide trichlorides makes PuCl3 less usable for weapons applications. The presence of lanthanide trichlorides in the molten fuel salt 108 reduces the usability of the Pu present in the molten fuel salt 108 in the event one attempts to apply a chemical process to separate the Pu from the rest of the molten fuel salt. In this sense, the lanthanides “ride along” with the Pu during some forms of chemical separation. This feature provides at least three benefits. First, the lanthanides cause the ultimate Pu sample to become more radioactive, making it more difficult to handle, shield, etc. Second, the lanthanides increase heat generation within the Pu sample, again, making the Pu more difficult to handle, shield, etc., as it may reach temperatures above the Pu melting point. Three, the presence of lanthanides changes the critical mass of the material such that the reaction process within a given Pu sample is far less efficient than a lanthanide-free sample. As such, in the case of a lanthanide-loaded Pu sample, more Pu material would be required for weapon device purposes, making weapons use more difficult and unwieldy. Further, uranium chemically separated from the mixture is not suitable for weapons applications as it is low enrichment uranium (LEU). It is noted that while some lanthanides may be formed in the fuel salt 108 as fission products during operation of the nuclear reactor 100, it is contemplated herein that the lanthanides of the present embodiment are pre-loaded into the nuclear fuel salt 108 prior to start-up of the reactor 100 and, thus, prior to the production of any significant amount of plutonium. After operation has begun, the fuel salt will naturally become less suitable for weapons applications as lanthanide fission products are created and build up due to the chain reaction. In one embodiment, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to start-up of the reactor 100. In one embodiment, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the reactor 100 reaching a selected reactivity threshold. By way of non-limiting example, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the reactor 100 reaching criticality or a sub-critical threshold. In another embodiment, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the generation of a selected threshold of plutonium (e.g., Pu-239) within the reactor (e.g., generated by enrichment of uranium in a uranium-plutonium breed-and-burn operation). By way of non-limiting example, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the generation of a selected amount of plutonium within the reactor. For instance, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the generation of 8 kg of plutonium within the reactor 100. In another instance, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the generation of 4 kg of plutonium within the reactor 100. In yet another instance, the one or more lanthanides are pre-loaded into the molten fuel salt 108 prior to the generation of 2 kg of plutonium (and so on) within the reactor 100. It is noted that the above plutonium masses are not limitations on the present embodiment and are provided merely for illustrative purposes as any plutonium threshold may be implemented in the context of the present embodiment. In another embodiment, the one or more lanthanides may be mixed with the molten fuel salt 108 such that the resulting lanthanide-loaded fuel salt has a lanthanide concentration from 0.1 and 10% by weight. In another embodiment, the one or more lanthanides may be mixed with the molten fuel salt 108 such that the resulting lanthanide-loaded fuel salt has a lanthanide concentration from 4 and 8%. In yet another embodiment, the selected lanthanide or lanthanides may be mixed with the molten fuel salt 108 in such proportions to achieve a threshold FOM that is <1.0, such as for example, an FOM threshold of less than 0.99, 0.98, 0.97, 0.96 or 0.95. In some embodiments, an FOM threshold of less than 0.95 may be desired such as less than 0.9 or 0.8. In one embodiment, the one or more lanthanides may include one or more of La, Ce, Pr, or Nd. In another embodiment, in the case of a chloride-based molten nuclear fuel salt 108, the one or more lanthanides may be mixed into the molten nuclear fuel salt 108 by mixing the molten fuel salt 108 with one or more lanthanide chlorides. By way of example, the one or more lanthanide chlorides may include one or more of LaCl3, CeCl3, PrCl3 or NdCl3. In another embodiment, in the case of a chloride-based molten nuclear fuel salt 108, the one or more lanthanides (or one or more lanthanide chlorides) may be mixed into the molten nuclear fuel salt 108 by mixing the molten fuel salt 108 with one or more carrier salts (e.g., NaCl) loaded with one or more lanthanides or lanthanide chlorides. In another embodiment, the mixture of molten nuclear fuel salt and the at least one lanthanide is formed outside of the fast spectrum molten salt nuclear reactor. By way of non-limiting example, the mixture of molten nuclear fuel salt 108 and the one or more lanthanides may be formed by mixing a volume of molten nuclear fuel salt 108 (prior to loading into reactor 100) and the one or more lanthanides (or lanthanides chlorides) in a separate mixing station external to the reactor core section 102 of the reactor 100 or after a predetermined period of time after start up when an expected amount of Pu is modeled to be bred up in the core. In another embodiment, the mixture of molten nuclear fuel salt and the at least one lanthanide is formed inside of the fast spectrum molten salt nuclear reactor. By way of non-limiting example, the mixture of molten nuclear fuel salt 108 and the one or more lanthanides may be formed by mixing a volume of one or more lanthanides (or lanthanides chlorides) into the molten nuclear fuel salt 108 contained within the primary circuit (e.g., reactor core section 102, primary coolant system 110 and the like) prior to start-up of the reactor 100. FIG. 15 illustrates an embodiment of a process flow 1500 representing example operations related to fueling a fast spectrum molten salt nuclear with nuclear fuel pre-loaded with one or more lanthanides, in accordance with one or more embodiments of the present disclosure. In FIG. 15, discussion and explanation may be provided with respect to the above-described examples of FIGS. 1A-1F, and/or with respect to other examples and contexts. It should be understood that the operational flows may be executed in a number of other environments and contexts, and/or in modified versions of FIGS. 1A-1F. Also, although the operations of FIG. 15 are presented in the sequence(s) illustrated, it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. In operation 1502, the process 1500 includes providing a molten nuclear fuel salt. By way of non-limiting example, a selected volume of a molten nuclear fuel salt may be provided. For instance, the molten nuclear fuel salt may include, but is not limited to, any chloride-based fuel salt described throughout the present disclosure. In another instance, the molten nuclear fuel salt may include, but is not limited to, any fluoride-based fuel salt described throughout the present disclosure. In operation 1504, the process 1500 includes providing at least one lanthanide. By way of non-limiting example, one or more lanthanides, such as, but not limited to, one or more of La, Ce, Pr, or Nd are provided. In one embodiment, the one or more lanthanides are provided in the form of a lanthanide salt. For example, the one or more lanthanides may be provided in the form of a lanthanide salt chemically compatible with the molten nuclear fuel salt of operation 1502. For instance, in the case of a chloride-based molten nuclear fuel salt, the one or more lanthanides may be provided in the form of one or more lanthanide salts, such as, but not limited to, LaCl3, CeCl3, PrCl3 or NdCl3. In another embodiment, a selected volume of one or more lanthanides (or one or more lanthanide salts) may be provided in the form of a mixture of one or more lanthanides (or one or more lanthanide salts) with an additional salt, such as, but not limited to, a carrier salt compatible with the molten nuclear fuel salt of operation 1502. In operation 1506, the process 1500 includes mixing the molten nuclear fuel salt with the at least one lanthanide to form a lanthanide-loaded molten nuclear fuel salt prior to start-up of the fast spectrum molten salt nuclear reactor or after a determined amount of Pu has been bred up. In one embodiment, the volume of molten fuel salt provided in operation 1502 is mixed with the one or more lanthanides (or one or more lanthanide salts) of operation 1504 such that the resulting molten salt mixture has a lanthanide content level from 0.1-10% by weight. By way of non-limiting example, the volume of molten fuel salt provided in operation 1502 may be mixed, but is not required to be mixed, with the one or more lanthanides (or one or more lanthanide salts) of operation 1504 such that the resulting molten salt mixture has a lanthanide content level from 4-8% by weight. In operation 1508, the process 1500 includes supplying the lanthanide-loaded molten nuclear fuel salt to at least a reactor core section of the fast spectrum molten salt nuclear reactor. In one embodiment, the mixture of operation 1506 may be formed by mixing the volume of molten fuel salt with the one or more lanthanides (or one or more lanthanide salts) inside of the fast spectrum molten salt nuclear reactor 100. In one example, the lanthanides may be added to the molten fuel salt within the reactor core. In another embodiment, the mixture of operation 1506 may be formed by mixing the volume of molten fuel salt with the one or more lanthanides (or one or more lanthanide salts) outside of the fast spectrum molten salt nuclear reactor 100, such as, but not limited to, a mixing vessel. In this regard, following the mixture of the molten fuel salt with the one or more lanthanides (or one or more lanthanide salts), the lanthanide loaded salt mixture may be loaded into the reactor 100. As discussed above, a goal of the method 1500 is to make the fuel salt less attractive for use as feedstock for weapons development. An aspect of embodiments of the method 1500 is that the dose, that is the radiation exposure from the lanthanide-loaded fuel salt, is increased. The amount of lanthanides added may be determined based on a target dose. For example, the Department of Energy and other regulatory bodies have published recommended thresholds for what are referred to as “self-protecting limits” at or beyond which that body believes the material is no longer attractive for weapons use. One such attractiveness measure may be dose, which may be made so high that a recipient is exposed to so much radiation that the recipient is prevented from completing an intended task by the damage caused by the exposure. One such dose limit is 100 rads per hour (rads/hr), another is 500 rads/hr and a third is 1,000 rads/hr, all measured at a distance of one meter. However, limits as high as 10,000 rad/hr have been proposed and may be used. Embodiments of the method 1500 can be adapted to provide a fuel salt having any desired dose. Another such attractiveness measure is the FOM, as described above. As described, based on that measure, initial fuel salts artificially modified to have an FOM of less than 1.0 are deemed unattractive for weapons use. In an embodiment, the selected lanthanide or lanthanides may be mixed with the molten fuel salt 108 in such proportions to achieve a threshold FOM that is <1.0. In alternative embodiments, more stringent FOM thresholds of less than 0.99, 0.98, 0.97, 0.96 or 0.95 may be selected and lanthanides or other ingredients altering the bare critical mass, M, the heat content, h, and the dose, D, factors of the FOM equation to achieve the desired threshold may be added. In some embodiments, an FOM threshold of less than 0.95 may be desired such as less than 0.9 or 0.8. The lanthanides used may be any lanthanide, however, particularly high dose and long-lived lanthanide isotopes are most suitable. In addition to lanthanides, radioactive isotopes of other elements may be used to increase the dose of a fuel salt. These include caesium-137 and iodine-121. Activated Anti-Proliferation Dopants Another anti-proliferation technique is to dope the fuel salt with one or more elements (referred to herein as activation dopants) that, upon exposure to neutrons such as would occur in the fuel salt when a reactor is in operation, undergo a nuclear reaction to, directly or indirectly, form highly active “protecting isotopes” (of the same element as the activation dopant or a different element), thereby increasing the fuel's dose value, D, in the FOM equation sufficiently to achieve an FOM<1.0 within some number of days, e.g., 1 day, 2 days, 5 days, 10 days, 30 days, 45 days, 60 days, 100 days, or even 200 days of operation of the reactor. During fission of a traditional fuel salt, as described elsewhere in this document such as UCl3-UCl4—[X]Cl, weaponizable materials such as Pu-239 or U-235 will be created along with other fission products. The mass of fission products will naturally increase over time, eventually reducing the FOM of the reacted fuel salt to an FOM<1.0 naturally. Depending on the particular fuel salt and the reactor used, however, there may be a period of days or months after the initiation of fission in which the FOM is greater than 1, but there is still an appreciable mass of weaponizable material that has been created. Activated anti-proliferation dopants can be used to ‘bridge’, so to speak, this period of high FOM by artificially causing the FOM to decrease after the initiation of fission. As the activated dopants do not affect the FOM calculation, this technique does not adversely affect the handlability of the fresh, unreacted fuel salt. However, as the fuel salt undergoes fission, the FOM of the fuel salt is artificially decreased quickly before a significant mass of weaponizable material is created. In an embodiment, these activated dopants are stable or only slightly active (i.e., less than 1 becquerel/gram of material) in the form in which they are added to the salt, but then converted to a more active or highly active protecting isotope when subjected to neutron radiation. Half-life of the protecting isotopes may also be taken into account with longer half-lives providing longer security than protecting isotopes with shorter half-lives. In general, suitable activation dopants are those that are stable or have an specific activity of 1 bq/g or less before activation (exposure to neutrons) and, after exposure, become a protecting isotope. In an embodiment, the activation dopants are present in the fuel in an amount sufficient to cause the fuel salt to achieve an FOM<1.0 within some number of days, e.g., 1 day, 2 days, 5 days, 10 days, or even 30 days of operation of the reactor. In an embodiment the protecting isotope(s) created further has a half-life greater than 1 months (e.g., from 1, 2, 3, 4, 5, 6, or 1 year on the low end of a range to 1,000,000 years on the high end of the range). An example of such an activation dopant is Co-59. Co-59 is a stable isotope of cobalt that is converted to Co-60, a highly active isotope of cobalt of about 10 bq/g and a half-life of 5.2 years, when subjected to neutron radiation. Another example is cesium in which stable Cs-133 can be converted into the protecting isotope Cs-134 or Cs-137 having a specific activity of about 10 bq/g and half-life of 30 years. Yet another possible activation dopant is cerium which can be converted to highly active Ce-144. Another dopant is bismuth which can be converted to Bi-207. Another activation dopant is iridium in which stable Ir-191 after neutron bombardment become Ir-192. Yet another dopant is radium-226 which is converted to actinium-227. Note also that activation dopants need not be directly converted into a protecting isotope that increases the FOM, but rather the protecting isotope may be found in the decay chain of isotopes of the direct fission product of the activation dopant. Many of the lanthanides can be used as activation dopants. Activation dopants may be added to the fuel salt in an amount and form suitable to remain in the fuel salt during fission. For example, in an embodiment compatible salts of the activation dopant and the protecting isotope are chemically soluble in the fuel salt. For example, in chloride fuel salts, chlorides of activation dopants may be added to the fuel salts to create a activation protected fuel salt. Examples of activation protected chloride fuel salts include an unprotect fuel salt (e.g., UCl3/NaCl, UCl3/UCl4/NaCl, UCl3/KCl, UCl3/UCl4/KCl or any other fuel salt embodiments described elsewhere) combined with one or more of the following activation dopant salts in which the cation is the activation dopant form of the isotope: CoCl3, CsCl, CeCl3, LaCl3, PrCl3, NdCl3, SmCl3, EuCl3, GdCl3, TbCl3, DyCl3, HoCl3, ErCl3, TmCl3, YbCl3, LuCl3, BiCl3, IrCl3, or RaCl2. For example, one embodiment of an activation protected fuel salt is UCl3/NaCl/CoCl3. Other embodiments include UCl3/KCl/CoCl3, UCl3/NaCl/CeCl3, UCl3/NaCl/CoCl3/CeCl3, UCl3/KCl/CoCl3/CsCl, UCl3/NaCl/CsCl, and UCl3/NaCl/LaCl3 to explicitly name but a few of the combinations described above. Protected fuel salts need not be entirely pure. Embodiments of a protected fuel salt include no more than 10 wt. % of other components not discussed above. More pure embodiments include protected fuel salts with no more than 5 wt. % and no more than 1 wt. % of such other components. Such other components are those that are neither unprotected fuel salts as described above nor salts of activation dopants. FIG. 23 illustrates an embodiment of a method of creating and using an activation protected fuel salt to provide anti-proliferation protection to a fuel salt. In the method 2300, an unprotected fuel salt, such as those described elsewhere, is provided in an unprotected fuel salt creation operation 2302. In an embodiment the FOM of the unprotected fuel salt is greater than 1.0. One or more activation dopants, as described above, are then added to the unprotected fuel salt to create an activation protected fuel salt in a protecting operation 2304. In an embodiment, the resulting activation protected fuel salt has an FOM that is greater than 1.0. In the protecting operation 2304, a sufficient total mass of activation dopants is added so that, upon fissioning of the fuel salt, the FOM of the fissioned protected fuel salt becomes less than 1.0 within some target time period of fissioning. Depending on the embodiment, the target time period of fission to achieve the FOM of less than 1.0 is 1 day, 2 days, 5 days, 10 days, 30 days, 45 days, 60 days, 100 days, 200 days or even 300 days of fission. The operations 2302 and 2304 may be performed in reverse order or even combined so that the protected fuel salt is created in a single operation. After the activation protected fuel salt is created, it is then fissioned in a nuclear reactor in a fission operation 2306, thereby creating a fissioned fuel salt. The fission operation 2306 is performed for a period of time, which may be continuous or intermittent. Regardless, as a result of the fissioning, the FOM of the fissioned fuel salt decreases during fissioning so that the FOM becomes less than 1.0 within the target time period due to the conversion of the activation dopants into protecting isotopes in fissioned fuel salt. Plutonium Chloride Fuel Salt In one embodiment, the fuel salt 108 may include a selected amount of plutonium. By way of example, in the case of a chloride-based nuclear fuel salt, the plutonium may be presented in the fuel salt 108 in the form of plutonium trichloride (e.g., PuCl3). Methods for manufacturing PuCl3 are known in the art and any suitable method may be used. PuCl3 has been shown to be compatible with uranium chloride salts. An embodiment utilizing PuCl3 is UCl4-UCl3—PuCl3—[X]Cl where, as above, [X]Cl is any additional, non-fissile salt. In these embodiments, the mol ratios of the any of various chloride salts may be determined as needed to obtain the desired melting point. In an embodiment, the amount of PuCl3 varies from a detectable amount of PuCl3 to 80 mol % and the other components (i.e., UCl4, UCl3, and [X]Cl) vary independently from 0 to 80%. Thus, embodiments such as UCl3— PuCl3—[X]Cl, and UCl4—PuCl3—[X]Cl are contemplated as are UCl4-UCl3—PuCl3—NaCl. Uranium Fuel Salt Embodiments The 17UCl3-71UCl4-12NaCl embodiment of fuel salts disclosed above represents the embodiment of the ternary uranium chloride salt with the highest uranium density for a fuel salt that has a melting point of 500° C. or less. Thus, this salt embodiment is appropriate for those situations and reactors for which maximizing the amount of uranium in fuel, and thereby minimizing the overall critical salt volume, is the only goal. However, the critical salt volume size is not the only cost driver in a molten salt reactor. Other characteristics of the fuel also affect the overall reactor costs including the thermal properties of the fuel salt such as volumetric heat capacity and thermal conductivity (which affect the size of the heat exchangers and piping needed, the velocities of the coolant and fuel salt through the system, and the volume of fuel salt, at any given time, that is outside of the reactor core being cooled), the corrosivity of the fuel salt (which affects the cost of materials needed for the salt-facing components of the reactor), and the amount of UCl4 in the salt (which, because of its relatively high vapor pressure, means that a higher UCl4 fuel salt will have a larger concentration of UCl4 in the headspace above the salt, requiring more expensive equipment and materials for handling the offgas). It has been determined that embodiments of fuel salts having relatively lower uranium density, but higher thermal conductivity and higher specific heat, can be more cost-effective than high-uranium content fuels salts in certain molten salt reactor designs. A fuel salt embodiment that is potentially more cost-effective than the 17UCl3-71UCl4-12NaCl embodiment is a ternary embodiment of UCl3-UCl4—NaCl having a melting point of less than 600° C.: a uranium density of greater than 1.5 g/cc; and a specific heat of greater than 600 J/kg-C. Embodiments of fuel salts may have melting points of less than 600° C., 550° C., 500° C., 450° C., 400° C., or even 350° C. Embodiments of fuel salts may have a uranium density of greater than 1.5 g/cc, 1.6 g/cc, 1.7 g/cc, 1.8 g/cc, 1.9 g/cc, 2 g/cc or even 2.1 g/cc. Embodiments of fuel salts may have a specific heat of greater than 600 J/kg-C, 700 J/kg-C, 800 J/kg-C, or even 900 J/kg-C. Embodiments of fuel salts may also have reduced amounts of UCl4 (relative to 17UCl3-71UCl4-12NaCl) in order to be more reducing and less corrosive than 17UCl3-71UCl4-12NaCl. Reduced corrosivity fuel salt allows for potentially less expensive components because the components are easier to fabricate and the salt-facing materials (such as nickel cladding instead of molybdenum cladding) are less expensive. Embodiments of uranium fuel salts have a molar fraction of UCl4 from 1% to 50% by molar fraction UCl4. Less corrosive embodiments of fuel salts may have less than 50 mol % UCl4, less than 40%, 30%, 20%, 15% or even less than 10 mol % UCl4. For example, fuel salts having from 2% to 30% by molar fraction UCl4, from 5% to 20% by molar fraction UCl4, and from 8% to 12% by molar fraction UCl4 are contemplated. In some embodiments, less corrosive uranium fuel salt embodiments may have only trace (less than 1%), but measurable, amounts of UCl4. Embodiments of fuel salts have a molar fraction of UCl3 from 1% to 33% by molar fraction UCl3. Embodiments of fuel salts have a molar fraction of NaCl wherein the fissionable fuel salt has from 40% to 66% by molar fraction NaCl. Based on thermal calculations, an example of a fuel salt embodiment as described above is 30UCl3-10UCl4-60NaCl. Table 5, below, illustrates the difference in calculated material properties at 650° C. between the 30UCl3-10UCl4-60NaCl fuel salt and the high-uranium-density embodiment of 17UCl3-71UCl4-12NaCl. Table 6, below, illustrates how the 30UCl3-10UCl4-60NaCl embodiment fuel salt improves the performance of a nominally-sized (2500 W), representative molten salt reactor relative to the 17UCl3-71UCl4-12NaCl fuel salt. TABLE 5Comparison of Thermal Properties Fuel Salt EmbodimentsFuel Salt17UCl3—71UCl4—12NaCl30UCl3—10UCl4—60NaClMelting Point (° C.)491-512508 estimated, (505.6measured, see below)Density (g/cc)3.683.44Uranium density (g/cc)2.271.83Specific Heat (J/kg-C.)544937Volumetric Heat Capacity (J/m3)2.01e63.22e6 TABLE 6Comparison of Thermal Properties Fuel Salt EmbodimentsFuel Salt17UCl3—71UCl4—12NaCl30UCl3—10UCl4—60NaClNominal Reactor Power (W)25002500Temperature difference across7885primary heat exchanger (ΔT)Fuel Salt Flow Rate Through77Heat Exchangers (m/s)Mass Flow Rate (kg/s)60,00031,400Vol. Flow Rate Through Heat16.39.1Exchangers (m3/s)Minimum Heat Exchanger2.331.30Cross-sectional Area (m2) As shown by the Tables, above, molten salt reactors utilizing embodiments of fuel salts can be operated at lower fuel salt flowrates because of the improved heat transfer properties, thus allowing both small pumps to be utilized. Molten salt reactors utilizing embodiments of fuel salts with from 40% to 66% by molar fraction NaCl will require a relatively larger core to have a comparable mass of uranium and/or power generation capability as opposed to more uranium-dense embodiments. However, molten salt reactors utilizing some embodiments of fuel salts with from 40% to 66% by molar fraction NaCl are calculated to require a lower total volume of fuel salt overall to operate because less fuel salt will be needed outside of the reactor for cooling purposes. This is even though the fuel salt embodiments are less dense in uranium. As fuel salt is very expensive, this reduction in the total amount of fuel to operate a reactor is a significant cost savings. Additional benefits of the fuel salt embodiments are stronger natural circulation in the core, reduced pump size because of the reduced volumetric flow rates, less expensive components due to ease of fabrication and cheaper materials, and decreased maintenance costs due to reduced radiation damage. An example of fuel salts was manufactured in the lab. In the experiment, 0.12272 g of UCl3, 0.04792 g of UCl4 and 0.04089 g of NaCl were combined to form 0.21153 g of 30.143 mol % UCl3-10.671 mol % UCl4-59.186 mol % NaCl. A 31.31 mg sample of this compound was analyzed using thermogravimetric and differential scanning calorimetry analysis (TGA-DSC) using a Netzch STA 449 F3 Jupiter simultaneous thermal analyzer. The TGA-DSC analysis determined that the melting temperature of the sample was 505.6° C. FIG. 22 plots the location of the manufactured fuel salt on the ternary diagram of FIG. 4. The calculations of FIG. 4 for the manufactured embodiment identify the melting point as 508° C. As mentioned above, the laboratory analysis indicates that the measured melting point is 505.6° C. While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” The term “about” is not intended to either expand or limit the degree of equivalents which may otherwise be afforded a particular value. Further, unless otherwise stated, the term “about” shall expressly include “exactly,” consistent with the discussions regarding ranges and numerical data. The term “about” in the context of the present disclosure means a value within 15% (±15%) of the value recited immediately after the term “about,” including any numeric value within this range, the value equal to the upper limit (i.e., +15%) and the value equal to the lower limit (i.e., −15%) of this range. For example, the value “100” encompasses any numeric value that is between 85 and 115, including 85 and 115 (with the exception of “100%”, which always has an upper limit of 100%). Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of “4% to 7%” should be interpreted to include not only the explicitly recited values of about 4 percent to about 7 percent, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 4.5, 5.25 and 6 and sub-ranges such as from 4-5, from 5-7, and from 5.5-6.5; etc. This same principle applies to ranges reciting only one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B.” In some instances, one or more components may be referred to herein as “configured to,” “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Those skilled in the art will recognize that such terms (e.g., “configured to”) can generally encompass active-state components and/or inactive-state components and/or standby-state components, unless context requires otherwise. With respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise. It will be clear that the systems and methods described herein are well adapted to attain the ends and advantages mentioned as well as those inherent therein. Those skilled in the art will recognize that the methods and systems within this specification may be implemented in many manners and as such is not to be limited by the foregoing exemplified embodiments and examples. In this regard, any number of the features of the different embodiments described herein may be combined into one single embodiment and alternate embodiments having fewer than or more than all of the features herein described are possible. While various embodiments have been described for purposes of this disclosure, various changes and modifications may be made which are well within the scope of the technology described herein. For example, although not explicitly stated Raman spectroscopy may be but one of many techniques used to monitor fuel salt quality during operation of a molten salt reactor and, likewise, multiple Raman probes may be used in order to get an understanding of the variations in fuel salt quality at different locations within the reactor. Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the disclosure and as defined in the appended claims.
	abstract	A fast, economical, and compact x-ray beam chopper with a small mass and a small moment of inertia whose rotation can be synchronized and phase locked to an electronic signal from an x-ray source and be monitored by a light beam is disclosed. X-ray bursts shorter than 2.5 microseconds have been produced with a jitter time of less than 3 ns.
	description	The present invention relates to a technique for managing a large group of steam traps, valves, and other devices installed in a plant. An example involving steam traps will now be described. To manage a large group of steam traps (referred to hereinbelow merely as “traps”) installed in a plant, a method has conventionally been adopted in which, for example, managed trap Nos. 1 to 200 are selected from a group of 1000 managed traps that are assigned control numbers 1 to 1000, and each of the selected traps is tested for malfunctions in a particular year. Managed trap Nos. 201 to 400 are each tested for malfunctions in the next year, and managed trap Nos. 401 to 600 are each tested for malfunctions in the year after that. In other words, a method is adopted in which partial tests are periodically performed to test only some of the managed traps, and the plurality of managed traps subjected to the partial test is sequentially rotated. When a malfunctioning device is detected in a group of tested traps being handled during each cycle of partial testing, the malfunctioning trap is replaced or repaired. In cases in which a comprehensive trap management log (e.g., a management database) is created so that a test result is recorded for each and every managed trap, the test result for each trap in a group of tested traps being handled during each cycle of partial testing is added to and recorded in the management log. The present applicant has previously proposed a steam trap management method (see Patent Document 1 below) that is separate from the above-described management method. According to the proposed method, all the managed traps, i.e., both normally functioning traps and malfunctioning traps, are collectively replaced with recommended traps, a new trap management log is created, a complete test is then periodically performed to determine whether any trap in the entire group of managed traps (i.e., collectively replaced traps) is operating normally or has a malfunction, the test result for each of the tested traps handled during each cycle of complete testing is added to and recorded in the trap management log (i.e., the log is updated), and a trap that has been found to be malfunctioning is replaced or repaired. [Patent Document 1] Japanese Laid-open Patent Publication No. 2002-140745 However, the first of the conventional management methods described above involves sequentially rotating the managed traps being tested during periodic partial testing. The result is that when a test result for each of a group of tested traps subjected to each cycle of partial testing is added to and recorded in a trap management log, mutually different test implementation conditions, such as the test period, the number of tests, and the test interval, are included at the same time in the test result for each managed trap recorded in the trap management log. For this reason, even if an analysis is made of the service conditions of each of the managed traps, the cause of the malfunction, or other information based on the test results for each of the managed traps recorded in the trap management log, the analysis will not be made under identical comparison conditions for each managed trap. A problem is accordingly presented in that inaccuracies will occur when the analysis is made of the service conditions of each of the managed traps, the cause of the malfunction, or other information. On the other hand, the second of the conventional management methods described above involves periodically performing a complete test for all of the managed traps, and adding to and recording in a trap management log test results for each of the managed traps for each cycle of complete testing. Therefore, if an analysis is to be made of the service conditions of each of the managed traps, the cause of the malfunction, or other information based on the test results for each of the managed traps recorded in the trap management log, the analysis will be performed under the identical comparison conditions (e.g., the test period, the number of tests, and the test interval) for each of the managed traps; and an accurate analysis can be performed in regard to these aspects. Nevertheless, the fact remains that no method has yet to be adequately established for accurately and efficiently allowing an analysis to be performed on the service conditions of each of the managed traps, the cause of the malfunction, or other information. In view of the above-described situation, a principal object of the present invention is to provide a device management method, an analysis system, and a data structure for analysis that can be used to overcome the above-described problems. A first aspect of the device management method of the present invention is characterized in comprising: periodically performing a complete test involving the entire number of devices in a large group of managed devices to determine whether the devices are operating normally or have a malfunction; recording a test result for each cycle of the complete test; replacing or repairing a device that has been found to be malfunctioning; and creating analysis data indicating the malfunctioning frequency of each managed device based on the test result of a complete test that spans a plurality of cycles. According to this arrangement, analysis data indicating the malfunctioning frequency (i.e., the number of malfunctions per unit period) of each managed device are created based on the test result of a complete test that spans a plurality of cycles obtained through periodic complete testing. It is accordingly possible to obtain analysis data showing the malfunctioning frequency of each managed device as determined under the same comparison conditions for all of the managed devices (i.e., conditions where the test period, the number of tests, the test interval, and the like are the same). Accordingly, if an analysis is thus performed using analysis data showing the malfunctioning frequency of each managed device as determined under the same comparison conditions, then in the case that, e.g., a specific device among the managed devices has a higher malfunctioning frequency than the others even if the devices are the same model, it will be possible to make a presumption, with a high degree of certainty, that the problem relates not to the device itself, but to the conditions under which the device in question was installed or used; or otherwise to make an accurate and efficient analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other aspects. The device management method is extremely useful in this regard. As used with reference to this arrangement, the term “periodic complete test” is not limited to a complete test performed at precise predetermined intervals, but also refers to a complete test performed, for example, approximately every six months, a complete test performed approximately every year, or any other complete test that can be regarded as being performed on a roughly regular basis. The same applies hereinbelow. Also, the term “malfunctioning frequency of a managed device” does not refer to the malfunctioning frequency of one managed device as such (i.e., the malfunctioning frequency of a single device) but, strictly speaking, refers to the malfunctioning frequency of a device provided to an installation site that accommodates a single managed device. Therefore, a case may be considered in which two malfunctions occur in the managed devices on a single installation site, and the managed devices are replaced each time a malfunction occurs. In such a case, each of the replaced devices experiences only one malfunction as such, but the managed devices on this installation site are considered to have two malfunctions when the malfunctioning frequency is calculated. The same applies hereinbelow. A second aspect of the device management method of the present invention is characterized in comprising: periodically performing a complete test involving the entire number of devices in a large group of managed devices to determine whether the devices are operating normally or have a malfunction, and classifying each of the managed devices into a plurality of classification categories according to a prescribed classification criterion; recording a test result for each cycle of the complete test; replacing or repairing a device that has been found to be malfunctioning; and creating analysis data indicating the relation between the malfunctioning frequency and the plurality of classification categories for each of the managed devices, or creating analysis data indicating the malfunctioning frequency of each managed device by classification category, based on the test result of a complete test that spans a plurality of cycles and on the classification category to which each of the managed devices belongs. According to this arrangement, it is possible to determine either set of analysis data under the same comparison conditions for all of the managed devices; i.e., conditions where the test period, the number of tests, the test interval, and the like are the same. Accordingly, if an analysis is thus performed using analysis data determined under the same comparison conditions, then in the case that, e.g., one of the managed devices that has an “A” classification category has a higher malfunctioning frequency than devices having another classification category, even if the installation conditions are the same, it will be possible to make a presumption, with a high degree of certainty, that the device belonging to the “A” classification category is incompatible with the given installation conditions; or otherwise to make an accurate and efficient analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other aspects. The device management method is extremely useful in this regard. A third aspect of the device management method of the present invention is characterized in comprising: periodically performing a complete test involving the entire number of devices in a large group of managed devices to determine whether the devices are operating normally or have a malfunction, and classifying each of the managed devices into a plurality of classification categories for each of a plurality of prescribed classification criteria according to the classification criterion; recording a test result for each cycle of the complete test; replacing or repairing a device that has been found to be malfunctioning; and creating analysis data indicating the relation between the malfunctioning frequency and the plurality of classification categories for each of the classification criteria for each of the managed devices, or creating analysis data indicating the malfunctioning frequency of each managed device by classification category for each of the classification criteria, based on the test result of a complete test that spans a plurality of cycles and on the classification category for each of the classification criteria to which each of the managed devices belongs. According to this arrangement, it is possible to obtain either set of analysis data under the same comparison conditions for all of the managed devices; i.e., conditions where the test period, the number of tests, the test interval, and the like are the same. Accordingly, if an analysis is thus performed using analysis data determined under the same comparison conditions, then in the case that, e.g., one of the managed devices that belongs to an “A1” classification category in the classification according to an “A” classification criterion and to a “B2” classification category in the classification according to a “B” classification criterion has a higher malfunctioning frequency than other devices, even if the installation conditions are the same, it will be possible to make a presumption, with a high degree of certainty, that the device belonging to the “A1/B2” classification category is incompatible with the given installation conditions; or otherwise to make an accurate and efficient analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other aspects. The device management method is extremely useful in this regard. A fourth aspect of the device management method of the present invention is characterized in comprising: performing a retest for each cycle of the complete test to determine whether the replaced or repaired device is operating normally or has a malfunction; finishing the replacing or repairing of the device when the device is confirmed to be operating normally as a result of the retest; and when the device is confirmed to be malfunctioning as a result of retesting, repeating the replacing or repairing of the device until the device is confirmed to be operating normally as a result of retesting. According to this arrangement, the replacing or repairing of the device is performed until the device is confirmed to be operating normally as a result of retesting. It is accordingly possible to prevent a malfunctioning device from being left in a malfunctioning state as a result of a replacement or repair failure in each cycle of the complete test, and to enable the malfunctioning device to be reliably placed in a normal state. It is accordingly possible to increase the validity of analysis data created on the basis of test results for complete tests spanning a plurality of cycles; i.e., the validity of analysis data obtained by determining the malfunctioning frequency of each of the managed devices under the same comparison conditions. It is also possible to increase the accuracy with which such analysis data is used to make analyses of the service conditions of each of the managed traps, the cause of the malfunction, or other information. A first aspect of the analysis system of the present invention is characterized in comprising: input means for inputting a test result of a complete test involving the entire number of devices in a large group of managed devices to determine whether the devices are operating normally or have a malfunction; storage means for accumulating and storing the test result of each cycle of the complete test that has been input by the input means; and arithmetic means for creating, in accordance with a preset program, analysis data that shows the malfunctioning frequency of each of the managed devices on the basis of the test result of the complete test that spans a plurality of cycles, as stored in the storage means. According to this arrangement, the test results for each cycle of the complete test are input by the input means, whereas the test results for each cycle of the complete test that have been inputted are accumulated and stored in the storage means. The storage means accordingly stores the test results for a complete test spanning a plurality of cycles. Since the arithmetic means creates, in accordance with a preset program, analysis data that shows the malfunctioning frequency of each of the managed devices on the basis of the test result of the complete test that spans a plurality of cycles as stored in the storage means, it is possible to obtain analysis data showing the malfunctioning frequency for each of the managed devices as determined under the same comparison conditions for all of the managed devices; i.e., conditions where the test period, the number of tests, the test interval, and the like are the same. Accordingly, if the analysis data is used to make an analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other information, then it will be possible to make an accurate and efficient analysis in the same manner as with the device management method of the first aspect. The analysis system is extremely useful for device management in this regard. Furthermore, the fact that the analysis data can be automatically created by the arithmetic means makes it possible to facilitate and streamline the entire analysis operation, including the creation of the analysis data, and hence to facilitate and streamline the entire device management operation. A second aspect of the analysis system of the present invention is characterized in comprising: input means for inputting a test result of a complete test involving the entire number of devices in a large group of managed devices to determine whether the devices are operating normally or have a malfunction, and a classification category to which each of the managed devices belongs; storage means for accumulating and storing the test result of each cycle of the complete test that has been input by the input means, and for storing the associated classification category for each of the managed devices as input by the input means; and arithmetic means for creating, in accordance with a preset program, analysis data indicating the relation between the malfunctioning frequency and the plurality of classification categories for each of the managed devices, or analysis data that shows the malfunctioning frequency of each of the managed devices by classification category, based on the test result of the complete test that spans a plurality of cycles and the associated classification category to which each of the managed devices belongs, as stored in the storage means. According to this arrangement, the test results for each cycle of the complete test are input by the input means, whereas the test results for each cycle of the complete test that have been inputted are accumulated and stored in the storage means. The storage means accordingly stores the test results for a complete test spanning a plurality of cycles, while also storing the associated classification category to which each of the managed devices belongs, as input by the input means. The arithmetic means creates, in accordance with a preset program, either of two sets of analysis data on the basis of the test result of the complete test that spans a plurality of cycles, and the classification category to which each of the managed devices belongs, as stored in the storage means. The creating of this data accordingly makes it possible to obtain analysis data under the same comparison conditions for all of the managed devices; i.e., conditions where the test period, the number of tests, the test interval, and the like are the same. Accordingly, if the analysis data is used to make an analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other information, based on the relationship with the plurality of classification categories, then it will be possible to make an accurate and efficient analysis in the same manner as with the device management method of the second aspect. The analysis system is extremely useful for device management in this regard. Furthermore, the fact that the analysis data can be automatically created by the arithmetic means makes it possible to facilitate and streamline the entire analysis operation, including the creation of the analysis data, and hence to facilitate and streamline the entire device management operation. A third aspect of the analysis system of the present invention is characterized in having: input means for inputting a test result of a complete test involving the entire number of devices in a large group of managed devices to determine whether the devices are operating normally or have a malfunction, and a classification category for each of a plurality of predetermined classification criteria to which each of the managed devices belongs; storage means for accumulating and storing the test result of each cycle of the complete test that has been input by the input means, and for storing the associated classification category for each of the classification criteria for each of the managed devices as input by the input means; and arithmetic means for creating, in accordance with a preset program, analysis data indicating the relation between the malfunctioning frequency and the plurality of classification categories for each of the classification criteria for each of the managed devices, or analysis data that shows the malfunctioning frequency of each of the managed devices by classification category for each of the classification criteria, based on the test result of a complete test that spans a plurality of cycles and the associated classification category for each of the classification criteria to which each of the managed devices belongs, as stored in the storage means. According to this arrangement, the test results for each cycle of the complete test are input by the input means, whereas the test results for each cycle of the complete test that have been inputted are accumulated and stored in the storage means. The storage means accordingly stores the test results for a complete test spanning a plurality of cycles, while also storing the associated classification category for each of the classification criteria to which each of the managed devices belongs, as input by the input means. The arithmetic means creates, in accordance with a preset program, either of two sets of analysis data on the basis of the test result of the complete test that spans a plurality of cycles, and the classification category for each of the classification criteria to which each of the managed devices belongs, as stored in the storage means. The creating of this data accordingly makes it possible to obtain analysis data under the same comparison conditions for all of the managed devices; i.e., conditions where the test period, the number of tests, the test interval, and the like are the same. Accordingly, if the analysis data is used to make an analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other information, based on the relationship with the plurality of classification categories for each of the classification criteria, then it will be possible to make an accurate and efficient analysis in the same manner as with the device management method of the third aspect. The analysis system is extremely useful for device management in this regard. Furthermore, the fact that the analysis data can be automatically created by the arithmetic means makes it possible to facilitate and streamline the entire analysis operation, including the creation of the analysis data, and hence to facilitate and streamline the entire device management operation. A first aspect of the analysis data structure of the present invention is a data structure for analysis data created for a device management in which a complete test involving the entire number of devices in a large group of managed devices is periodically performed to determine whether the devices are operating normally or have a malfunction, a test result is recorded for each cycle of the complete test, and a device that has been found to be malfunctioning is replaced or repaired; wherein the analysis data structure is characterized in being constituted to display a malfunctioning frequency for each of the managed devices as determined on the basis of test results of the complete test spanning a plurality of cycles. According to this arrangement, analysis data is used to display the malfunctioning frequency for each of the managed devices; i.e., the malfunctioning frequency determined under the same comparison conditions for all of the managed devices (conditions where the test period, the number of tests, the test interval, and the like are the same), as determined on the basis of test results of a complete test spanning a plurality of cycles, obtained using periodic complete tests. Accordingly, if an analysis is made of the service conditions of each of the managed traps, the cause of the malfunction, or other information, based on the malfunctioning frequency for each of the managed devices as displayed, then it will be possible to make an accurate and efficient analysis in the same manner as with the device management method of the first aspect. The analysis system is extremely useful for device management in this regard. A second aspect of the analysis data structure of the present invention is a data structure for analysis data created for a device management in which a complete test involving the entire number of devices in a large group of managed devices is periodically performed to determine whether the devices are operating normally or have a malfunction, each of the managed devices is classified into a plurality of classification categories according to a prescribed classification criterion, a test result is recorded for each cycle of the complete test, and a device that has been found to be malfunctioning is replaced or repaired; the analysis data structure characterized in being constituted to display the relation between the malfunctioning frequency and plurality of classification categories for each of the managed devices, or display the malfunctioning frequency for each of the managed devices by classification category, as determined on the basis of test results of the complete test spanning a plurality of cycles, and on the basis of the classification category to which each of the managed devices belongs. According to this arrangement, analysis data is used to display the relation between the malfunctioning frequency and the plurality of classification categories for each of the managed devices as determined under the same comparison conditions for all of the managed devices (i.e., conditions where the test period, the number of tests, the test interval, and the like are the same), or the malfunctioning frequency of each of the managed devices by classification category as determined under the same comparison conditions for all of the managed devices. Accordingly, if an analysis is made, in regard to the relationship with the plurality of classification categories, of the service conditions of each of the managed traps, the cause of the malfunction, or other information, based on the relation between the malfunctioning frequency and the plurality of classification categories for each of the managed devices, or the malfunctioning frequency of each of the managed devices by classification as displayed, then it will be possible to make an accurate and efficient analysis in the same manner as with the device management method of the second aspect. The analysis system is extremely useful for device management in this regard. A third aspect of the analysis data structure of the present invention is a data structure for analysis data created for a device management in which a complete test involving the entire number of devices in a large group of managed devices is periodically performed to determine whether the devices are operating normally or have a malfunction, each of the managed devices is classified into a plurality of classification categories for each of a plurality of prescribed classification criteria according to each of the classification criteria, a test result is recorded for each cycle of the complete test, and a device that has been found to be malfunctioning is replaced or repaired; the analysis data structure characterized in being constituted to display the relation between the malfunctioning frequency and plurality of classification categories for each of the classification criteria for each of the managed devices, or display the malfunctioning frequency for each of the managed devices by classification category for each of the classification criteria, as determined on the basis of test results of the complete test spanning a plurality of cycles, and on the basis of the classification category for each of the classification criteria to which each of the managed devices belongs. According to this arrangement, analysis data is used to display the relation between the malfunctioning frequency and the plurality of classification categories for each of the classification criteria for each of the managed devices as determined under the same comparison conditions for all of the managed devices (i.e., conditions where the test period, the number of tests, the test interval, and the like are the same), or the malfunctioning frequency of each of the managed devices by classification category for each of the classification criteria as determined under the same comparison conditions for all of the managed devices. Accordingly, if an analysis is made, in regard to the relationship with the plurality of classification categories for each of the classification criteria, of the service conditions of each of the managed traps, the cause of the malfunction, or other information, based on the relation between the malfunctioning frequency and the plurality of classification categories for each of the classification criteria for each of the managed devices, or the malfunctioning frequency of each of the managed devices by classification category for each of the classification criteria as displayed, then it will be possible to make an accurate and efficient analysis in the same manner as with the device management method of the third aspect. The analysis system is extremely useful for device management in this regard. The analysis data used in the implementation according to the aforedescribed aspects may be written data printed on paper or the like, electronic data displayed on a computer display, or any other type of data capable of displaying content. The display mode for the variety of relations indicated based on the analysis data when the aforedescribed aspects are implemented is not limited to a display mode that uses graphs, tables, or formulae to show the relation, and includes display modes in which the relations are indicated using drawings, symbols, colors, and the like. The mode for displaying the malfunctioning frequency in the analysis data is not limited to a numeric display of the frequency, and includes a numeric display of the number of malfunctions assuming that the sampling period is the same for all of the managed devices, and also includes a display mode for visually depicting the frequency and number of malfunctions using graphs, tables, drawings, symbols, colors, or the like. Another main subject matter of the present invention is a maintenance inspection support apparatus for performing maintenance inspection of a device installed in a plant based on a guideline selected from a plurality of maintenance inspection guidelines. The maintenance inspection support apparatus of the present invention comprises: a device layout data management unit for managing layout data of the device as obtained from device arrangement chart data that has been entered; a device attribute value acquisition unit for acquiring a problem device attribute value that has been identified using an identification code read from an ID tag attached to a problem device, which is to be subjected to a maintenance inspection and which is specified while device layout data managed by the device layout data management unit is being referenced; a device test data acquisition unit for acquiring device test data for the problem device; a device evaluation data generator for combining, for each device, the device attribute value acquired by the device attribute value acquisition unit and the device test data acquired by the device test data acquisition unit, and generating device evaluation data; a database management unit for appending a history code allowing the device evaluation data to be managed as a history, registering the device evaluation data in a database, and extracting device evaluation data that conforms to a search condition; a classification processor for classifying the device evaluation data while accessing the database via the database management unit, and referencing a classification criteria table; a device analysis processor for performing a historical evaluation of the device evaluation data extracted from the database or the device evaluation data classified by the classification processor, and analyzing an operating state of the device; and a display unit for displaying analysis results obtained using the device analysis processor. An important point regarding the maintenance inspection support apparatus shall be described below. In order for the analysis results obtained using the device analysis processor, or other data, to be used for managing the maintenance inspection operation of a plant, the device analysis processor computes graphs and evaluation maps showing the malfunctioning frequency of the devices based on the analysis results or device evaluation data obtained from the database via the database processing unit. These graphs and maps are displayed on the display unit, and the device status can be readily ascertained. There follow three examples of data types that can be acquired as device evaluation data. A first type is analysis data for indicating a malfunctioning frequency (the number of malfunctions per unit period) obtained on the basis of test results of a plurality of cycles of a periodic complete test pertaining to each device to be managed. If such analysis data is used, then in the case that, e.g., a specific device among managed devices of the same type has a higher malfunctioning frequency than the others, then it will be possible to presume that the problem relates not to the device itself, but to the conditions under which the device in question was installed or used. It will also be possible to make an accurate and efficient analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other aspects. A second type is analysis data for indicating a malfunctioning frequency of a managed device for each classification category to which the managed device belongs, on the basis of test results of a plurality of cycles of a periodic complete test pertaining to each device to be managed. An application-based classification category is provided; e.g., managed devices used in normal pipework, and managed devices used for main pipelines; the malfunctioning frequency of the managed device is measured for each of the classification categories; and the analysis data is obtained. Using analysis data obtained in this manner makes it possible to presume that in the case that a managed device having a specific classification category has a high malfunctioning frequency even if the installation conditions are the same, it will be possible to presume that the device having that classification category is incompatible with the given installation conditions. It is accordingly possible to make an accurate and efficient analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other aspects. A third type is analysis data for indicating a malfunctioning frequency of a managed device for a classification criterion to which the managed device belongs, on the basis of test results of a plurality of cycles of a periodic complete test pertaining to each device to be managed. “Classification criterion” refers, e.g., to a pipework application to which a managed device is attached, and a configuration of a managed device. Classification criteria are further broken into classification categories. For example, the classification categories described above, such as the devices used in normal pipework and the devices used in main pipelines, are grouped under the single classification criterion referred to as “applications. T” Classification categories such as “float-type,” “bucket-type,” and “disk-type” are grouped under the single classification criterion referred to as “configurations.” The malfunctioning frequency of managed devices according to classification criteria is obtained using these established groupings, whereby, in the case that a managed device belonging to a specific plurality of classification criteria has a high malfunctioning frequency, it will be possible to presume that the device in question is incompatible with the installation conditions. It is accordingly possible to make an accurate and efficient analysis of the service conditions of each of the managed traps, the cause of the malfunction, or other aspects. T Managed device Ic Test result N Malfunctioning frequency G, E Analysis data 2 Input means 14a, 14b Input means 17 Storage means Pb Preset program 16 Arithmetic means FIGS. 1 and 2 show a management unit 1 used in the management of a large group of vapor traps T installed in a chemical plant or other vapor-using facility. The management unit 1 is composed of a testing unit 2, a portable personal computer 3 (abbreviated as “portable PC” hereinbelow), and an ID tag reader 4. The testing unit 2 has a keypad 5 as an operating unit, a miniature display 6 as a display unit, an internal CPU 7 (central processing unit) as an arithmetic unit, and an internal memory 8 as a storage unit. A testing program Pa is stored in the memory 8. The testing unit 2 operates in accordance with the testing program Pa executed by the CPU 7. The testing unit 2 has a probe 9. The distal end of the probe 9 is provided with a sensor 10 for detecting the supersonic vibrations and temperature at an external surface of a trap T while pressed against the external surface of the trap, as shown in FIG. 3. Vibration and temperature signals sensed by the sensor 10 are input to the testing unit 2 via a connecting cord 11 (or an infrared communication means or other wireless communication means). The ID tag reader 4 is provided to the distal end of an arm 12 mounted on the probe 9, with the arm being able to be switched between the extended position shown by the broken line and the retracted position shown by the solid line. When the ID tag reader 4 is brought close to an ID tag 13 attached in the vicinity of each tested trap while the arm 12 is extended, the area number, trap number, and other trap identification information Ia of the corresponding trap T recorded in the ID tag 13 are read by the ID tag reader 4 and are input to the testing unit 2. The portable PC 3 has a keyboard 14a, stylus 14b, and mouse (not shown) as operating units; a display 15 as a display unit; an internal CPU 16 as an arithmetic unit; and an internal hard disk 17 as a storage unit. A management program Pb is stored on the hard disk 17. The portable PC 3 operates in accordance with the management program Pb executed by the CPU 16. The portable PC 3 can have two-way communication with the testing unit 2 via a connecting cord 18 (or an infrared communication means or other wireless communication means). The trap identification information Ia that is read by the ID tag reader 4 is input to the testing unit 2 and the portable PC 3. The memory 8 of the testing unit 2 stores the model, application, service vapor pressure, and other types of trap attribute information Ib of each of the tested traps T. The testing unit 2 retrieves from the memory 8 the trap attribute information Ib of the tested trap T specified by the trap identification information Ia that was read by the ID tag reader 4. The trap attribute information Ib thus read and the vibrations and temperature sensed by the sensor 10 are evaluated using determination criteria information Da. The determination criteria information Da may, for example, include tables for calculating the vapor leakage rate or the like from the trap model, temperature, and vibration. The determination criteria information Da is stored in the memory 8. Obtaining the vapor leakage rate as a result of the evaluation makes it possible to determine whether the tested trap T is operating normally or has a malfunction. In addition, the malfunction category can also be determined, such as whether the leak is large, medium, or small, whether there is a blowout or an obstruction, or the like. The testing unit 2 stores the following information in the memory 8: trap reference information Id that may include a test date, notes, and a plurality of other entries that are input by operating the keypad 5 or the like for each of the tested traps T, and the results of determining whether the traps operate normally or have a malfunction, as well as the results of determining the malfunction category as trap test results Ic (trap test information). In the process, the trap test results Ic are correlated with the trap identification information Ia and trap attribute information Ib. These types of information are also transmitted to the portable PC 3. In the testing unit 2, the four types of information Ia, Ib, Ic, and Id about the tested traps T specified by the trap identification information Ia that was read by the ID tag reader 4 (or information about the tested traps T specified by operating the keypad 5 or in any other way) are displayed on the miniature display 6 in scrollable form. The hard disk 17 of the portable PC 3 stores a management database Db in which the trap attribute information Ib about the tested traps T (i.e., managed traps), the trap test results Ic of each of the tests performed by the testing unit 2, the trap reference information Id, and the like are recorded in relation with the trap identification information Ia. In the portable PC 3 that has received the trap test results Ic from the testing unit 2, a database update function is initiated, and the trap test results Ic and trap reference information Id are cumulatively recorded in the management database Db for the specified tested traps T. The management database Db may not have any entries of the managed traps T that correspond to the trap identification information Ia read by the ID tag reader 4. When this happens, the portable PC 3 creates a record as a database creation function wherein an entry that is related to the managed traps T (i.e., unrecorded traps) and corresponds to the trap identification information Ia is newly established in the management database Db. The trap test results Ic and trap reference information Id about the managed traps T transmitted from the testing unit 2 are recorded in the management database Db at this point. In addition, the portable PC 3 has a database display function whereby the four types of information Ia to Id about each of the managed traps T recorded in the management database Db are displayed on the display 15 in tabular form, as shown in FIG. 4. In this database display, the table on the display 15 is scrolled so as to display entries related to tested traps T specified by the trap identification information Ia that was read by the ID tag reader 4, or to tested traps T specified by operating the keyboard 14a, stylus 14b, or the like. In cases in which the information Ia to Id about each of the managed traps T has been written or rewritten by operating the keyboard 14a or the like, the content stored in the management database Db is subjected to a write or rewrite operation accordingly. The portable PC 3 (i.e., the management program Pb) has a mapping function and an analysis data creation function in addition to the database updating and creating function and the database display function described above. With the mapping function, a schematic facility chart image G showing the facility provided with a large group of managed traps T such as the one shown in FIG. 5 is displayed on the display 15 on the basis of facility chart information Dc stored on the hard disk 17. This display is provided instead of the above-described tabular database display shown in FIG. 4. In addition, display elements E (icons) that show individual tested traps T are overlaid on the facility chart image G and displayed on the display 15 in an arrangement that conforms to the actual trap positions. The overlaying is performed on the basis of the trap arrangement information Dd about each of the tested traps T that is stored on the hard disk 17 in the same manner. When any of the display elements E displayed in the facility chart image G on the display 15 of the portable PC 3 is selected by operating the stylus 14b or the like and is designated for execution, the information Ia to Id about the managed trap T that corresponds to this display element E is read from the management database Db and displayed as a separate frame in the facility chart image G on the display 15. In addition, as an analysis information creation function of the portable PC 3, the application of the corresponding trap T can be displayed using differences in the shape of the display elements E on the basis of the trap attribute information Ib of each of the managed traps T recorded in the management database Db, as shown in FIG. 5. In this case, a square indicates a general use, a triangle indicates a trace use, and a circle indicates the main pipeline use. Based on the trap test result Ic for each managed trap T cumulatively recorded in the management database Db, and depending on the differences in the border color or pattern of the display elements E, the number N of malfunctions of the corresponding trap T in the most recent preset period (e.g., 3 years) is displayed. In this example, a thin solid border indicates zero times, a thin broken border indicates a single time, and a thick solid border indicates a plurality of times. As used herein, the term “number N of malfunctions (i.e., malfunctioning frequency in a preset period)” refers to the number of malfunctions experienced by managed traps T installed at a single installation site that accommodates the traps, rather than the number of malfunctions of a single managed trap T as such. A single entry or a plurality of entries in any type of information Ia to Id about the managed traps T is similarly displayed as the analysis data creation function in the form of a tabular database display in the portable PC 3, as shown in FIG. 4. In this display, the classification categories (i.e., general use, trace use, main pipeline use, and other classification categories in the “application” entry) of these entries are specified as search conditions by operating the keyboard 14a, the stylus 14b, or the like, whereupon the information Ia to Id recorded in the management database Db is displayed in tabular form on the display 15 only for the managed traps T that belong to these classification categories. For example, specifying “float type” as a search condition for the model entry in the trap attribute information Ib causes the information Ia to Id recorded in the management database Db to be displayed on the display 15 only for float-type managed traps T. The portable PC 3 further has the following analysis data creation function. When a graphic display is specified in a state in which two entries selected from the information Ia to Id about the managed traps T are indicated by operating the keyboard 14a, stylus 14b, or the like, the number of traps belonging to the classification categories of one of the entries and the number of traps belonging to the classification categories of the other entry (i.e., the number of traps in each classification category for the second entry) are displayed on the display 15 on the basis of the information Ia to Id recorded in the management database Db. The display is in the form of a 3D bar graph, pie graph, or other specified graph. For example, a graph is displayed on the display 15, as shown in FIG. 6, by indicating a model entry in the trap attribute information Ib and indicating entries classified by the malfunction categories in the trap test result Ic for an arbitrary cycle, and specifying a graphic display based on a 3D bar graph. Also, a graph is displayed on the display 15, as shown in FIG. 7, by indicating entries classified by the malfunction categories in the trap test result Ic for a preceding cycle and indicating entries classified by the malfunction categories in the trap test result Ic for the current cycle, and specifying a graphic display based on a pie graph. A large group of vapor traps T is managed according to the following sequence (a) to (f) using a management unit 1 configured as described above. (a) It is determined by consultations with the trap management requester which of the vapor traps at a facility are to be designated as managed traps T. Specifically, it is determined based on discussions with the management requester whether all the vapor traps at the facility are to be designated as managed traps T, only the vapor traps in some of the sections at the facility are to be designated as managed traps T, only the vapor traps belonging to a specific vapor system in the facility are to be designated as managed traps T, or the like. (b) Facility chart information Dc and trap arrangement information Dd, which are stored on the hard disk 17 of the portable PC 3, are created based on a facility arrangement chart, pipeline system chart, or the like presented by the management requester, and the facility chart information Dc and trap arrangement information Dd thus created are stored on the hard disk 17 of the portable PC 3. (c) As an initial operation, the test operator brings the management unit 1 to the installation site of each of the managed traps T while consulting the facility chart image G displayed on the display 15 of the portable PC 3 and the display elements E on the facility chart image G, attaches an ID tag 13 to each of the managed traps T, and reads the trap identification information Ia by using the ID tag reader 4. Entries related to each of the managed traps T are thereby created by the database creation function in the management database Db of the hard disk 17 in the portable PC 3. In addition, the trap identification information Ia and the display elements E for each of the managed traps T are correlated by the operation of a stylus 14b or the like. In addition to attaching ID tags 13 and reading the trap identification information Ia, the test operator also confirms the trap attribute information Ib and trap reference information Id for each of the managed traps T, and enters the trap attribute information Ib and trap reference information Id into the management database Db of the portable PC 3 by operating the keyboard 14a, stylus 14b, or the like. The management database Db is thus created anew for all the managed traps T. Furthermore, the ID tags 13 are attached, the trap identification information Ia is read, and the trap attribute information Ib and trap reference information Id is entered. The test operator thereby enters trap attribute information Ib and trap reference information Id for each of the managed traps T into the memory 8 of the testing unit 2 from the management database Db of the portable PC 3 for each of the managed traps T. The testing unit 2 is used to test each of the managed traps T, and the test results Ic are stored in the memory 8 of the testing unit 2 and are entered into the management database Db of the portable PC 3. (d) After the initial operation has concluded, the current condition (e.g., malfunction rate, total vapor leakage, monetary loss due to vapor leakage, and the like) of all the managed traps T is reported to the management requester on the basis of the trap test results Ic for the entire number of the managed traps T recorded in the management database Db of the portable PC 3. An initial overhaul is then performed by consultation with the management requester. The overhaul is either a complete overhaul in which the entire number of the managed traps T is replaced with recommended traps (e.g., traps with reduced vapor leakage when operating normally, traps more suitable for the installation conditions or service conditions, or the like), or a partial overhaul in which only malfunctioning managed traps T are repaired or replaced with recommended traps. In the initial overhaul, the replaced or repaired devices are retested using the testing unit 2 to determine whether the devices operate normally or have a malfunction. The repair or replacement is completed for those of the managed traps T that have been confirmed by the retesting to operate normally. For those of the managed traps T that have been confirmed by the retesting to have a malfunction, the repair or replacement is repeated until the retesting confirms that the devices operate normally. Once a replaced or repaired managed trap T is confirmed by the retesting to operate normally, a replacement or repair record is made for this managed trap T; i.e., the fact of the replacement or repair is recorded in the management database Db of the portable PC 3, as are the post-replacement or post-repair trap attribute information Ib, trap test result Ic, and trap reference information Id. (e) After the initial operation is completed, a complete test is performed periodically, such as annually or semiannually. The testing unit 2 is used to test the entire number of the managed traps T (i.e., to perform a test in which trap identification information Ia is read by the ID tag reader 4 for each trap T, and the probe 9 is brought against the trap T) irrespective of whether a complete or partial overhaul was performed as the initial overhaul. Each time the complete test is performed, trap test results Ic about each of the managed traps T is added to the management database Db. If a malfunctioning trap is detected, this trap is repaired or replaced with a recommended trap. In each cycle of complete testing, a replaced or repaired device is retested by the testing unit 2 to determine whether the device is operating normally or has a malfunction. This retesting is part of the complete test, similarly to an initial overhaul. A managed trap T that has been confirmed by the retesting to operate normally is not replaced or repaired, whereas a managed trap T that has been confirmed by the retesting to have a malfunction is repeatedly replaced or repaired until the retesting confirms that the device is operating normally. Once a replaced or repaired managed trap T is confirmed by the retesting to operate normally, a replacement or repair record is made for this managed trap T; i.e., the fact of the replacement or repair is added to the management database Db of the portable PC 3, as are the post-replacement or post-repair trap attribute information Ib, trap test result Ic, and trap reference information Id. In each cycle of complete testing, another testing mode can be adopted instead of the testing mode in which the management unit 1 composed of a testing unit 2, portable PC 3, and ID tag reader 4 is used by the test operator as a portable unit to test each managed trap T in the same manner as during the previous cycle of initial overhauling accompanied by the creation of a management database Db. Specifically, it is also possible to adopt a testing mode in which only the testing unit 2 provided with an ID tag reader 4 is used by the test operator as a portable unit to test each managed trap T, and the trap test result Ic and trap reference information Id about each of the managed traps T recorded in the memory 8 of the testing unit 2 is collectively entered into the management database Db of the portable PC 3 after the test. (f) The service condition of managed traps T, the cause of a malfunction, and the like are analyzed after each cycle of complete testing or in another suitable period by using an analysis data creation function of the portable PC 3 such as the one described above. Examples of analysis data creation functions include displaying the type of application based on the shape of a display element E, displaying the number N of malfunctions by the type of border on a display element E, displaying recorded information Ia to Id only for managed traps T of a specific classification category, or displaying a graph. The results of the analysis are reported to the management requester, and appropriate measures are taken for the facility based on the results. In performing maintenance inspections on traps T and other plant facility devices (the term “trap T” has been used here in relation to such devices, but the word “device,” which is a general term, will be adopted hereinbelow) at a plant facility, the above-described portable PC 3 uses a signal from the ID tag reader 4 or testing unit 2, and provides efficient assistance in performing maintenance inspections on plant facility devices. In particular, the computer provides efficient assistance to the operator when maintenance inspection is to be performed on a device used in a plant facility according to maintenance inspection guidelines. These guidelines include a complete overhaul strategy in which a complete overhaul is performed to replace the entire number of devices to be subjected to maintenance inspections with recommended devices, and a complete test involving the entire number of the managed devices is then periodically repeated; and a partial overhaul strategy in which a partial overhaul is performed to repair only those of the managed devices that have a malfunction, or to replace the malfunctioning devices with recommended devices, and a complete test involving the entire number of the managed devices is then periodically repeated. For this reason, the functions of the portable PC 3 are configured using programs and hardware such as those shown in FIG. 8. Graphic user interfaces are extensively used in the portable PC 3 in order to transmit information to the operator in an easily understandable manner by presenting a graphic display via the display 15, and to allow comments to be entered by the simple operation of the operating units 14a, 14b via a graphic screen. The unit that implements such a graphic user interface is a GUI unit 30. This unit operates in close coordination with the OS installed on the portable PC 3, and is linked with a functional unit involved in the maintenance inspection operation assistance provided by the portable PC 3 and described below. A device layout data management unit 31 performs a management task wherein device layout data is loaded from the outside. In the device layout data, device positions are linked to map data related to the plant site on the basis of device layout plan data digitized so as to indicate the layout of devices scheduled for maintenance inspections. When each device is subjected to a maintenance inspection, an assistance screen such as the one shown in FIG. 5 is displayed on the display 15 on the basis of the device layout data managed by the device layout data management unit 31, and the operator is notified of problem devices, which are devices that need to undergo a maintenance inspection next. Problem devices specified by the operator are confirmed by a problem device specifier 32. An identification symbol (trap identification information Ia) that is read by the ID tag reader 4 from an ID tag 13 attached to a problem device can be used as a key code for a device attribute value (trap attribute information Ib) stored in the memory 8 of the testing unit 2 in the above-described embodiment. Therefore, a device attribute value of the device specified by the identification symbol can be acquired by the portable PC 3. A device attribute value acquisition unit 33 is provided in order to acquire the device attribute value of the device specified via the ID tag 13 in this manner. The device specified by the ID tag 13, i.e., the problem device, is tested by the testing unit 2, whereby a test signal (trap test result Ic) sent from the testing unit 2 is processed by a device test data acquisition unit 34 as device test data that shows whether each device is operating normally or has a malfunction. The device attribute values acquired by the device attribute value acquisition unit 33 and device test data acquired by the device test data acquisition unit 34 are sent to a device evaluation data generator 35, and are combined there in a mode in which the corresponding devices are linked to specific identification symbols to form device evaluation data. The device evaluation data thus generated for each of the problem devices is stored in a database Db. The device evaluation data for each device is stored in the database Db each time a periodic maintenance inspection operation is performed, and this device evaluation data is treated as history information about each of the devices. For this reason, a database management unit 36 is provided for recording the device evaluation data in the database Db after a history code (date or the like) is added so that the history [of each device] can be managed, and extracting device evaluation data that matches search conditions in which history conditions are also included. Since the devices recorded in the database Db are sorted into a large group of classification categories in accordance with the specifications of these devices, a classification that corresponds to these classification categories is needed when the device evaluation data is analyzed and on other occasions. A function is therefore provided wherein the device evaluation data is classified while a classification processor 37 accesses the database Db and references a classification criteria table 38 via the database management unit 36. A device analysis processor 39 for analyzing the operational state of each device on the basis of the history of the device evaluation data has an algorithm for performing a statistical analysis in terms of malfunctioning frequency as described above, and also has a visualizing algorithm for visually representing the analysis results in the form of a graph, map, or other format. Since the malfunctioning frequency is significantly affected by the location or the conditions of use, the device evaluation data serving as the analysis source is used in accordance with the analysis target either in the form of data directly extracted from the database Db or in the form of data classified by the classification processor 37. For the analysis results and the like obtained by the device analysis processor 39 to be used in performing maintenance inspections in a plant facility, a performance computation unit 40 is provided with a function whereby the malfunction rate, total vapor leakage, monetary loss due to vapor leakage, and the like of each device are calculated and the economic results of the maintenance inspection operation are computed on the basis of the analysis results and of device evaluation data obtained from the database Db via the database management unit 36. The following types of maintenance inspection guidelines have been offered for use in the maintenance inspection of plant facility devices: a complete overhaul strategy in which a complete overhaul is performed to replace the entire number of devices to be subjected to maintenance inspections with recommended devices, and a complete test involving the entire number of the managed devices is then periodically repeated; and a partial overhaul strategy in which a partial overhaul is performed to repair only those of the managed devices that have a malfunction, or to replace the malfunctioning devices with recommended devices, and a complete test involving the entire number of the managed devices is then periodically repeated. Selection of either of the two strategies as appropriate varies with each plant facility. Therefore, the problem of which of the strategies to select in accordance with the plant facility scheduled for a maintenance inspection can be resolved by evaluating past performance. An assistance information generator 41 is accordingly provided. The assistance information generator 41 has an algorithm for generating support information (economic effects of each strategy at a variety of plant facilities, and the like) whereby either of the above-described two strategies is selected as a maintenance inspection guideline on the basis of economic effects evaluated by the performance computation unit 40. The algorithm for generating such support information can be constructed in a simple manner by adopting a decision theory system such as a neural network or an expert system. The assistance information generator 41 has an algorithm for selecting a recommended device for use in a specific site based on the analysis results, and is able to appraise the operator of a recommended device when a device is to be replaced at a specific site. Other embodiments of the present invention are described next. Vapor traps are given as examples of managed devices in the above-described embodiment, but the managed devices used in the implementation of the present invention are not limited to vapor traps alone, and may also include various valves or tanks, as well as production equipment and machine tools. According to the above embodiment, there is presented a device management method for classifying individual devices to be managed (traps to be managed) into a plurality of classification categories (e.g., normal use, trace use, and main pipeline use) according to a prescribed classification criterion (e.g., by application), and, based on test results for a complete test spanning a plurality of cycles and on the classification category to which each of the managed devices belongs, for creating analysis data indicating the malfunctioning frequency for each of the managed devices, the malfunctioning frequency for each of the managed devices by the classification category, and a relation between the malfunctioning frequency and the plurality of classification categories. It is also possible, however, to instead adopt a device management method for classifying individual devices to be managed into a plurality of classification categories for each of a plurality of prescribed classification criteria (e.g., by application) according to the classification criteria (e.g., normal use, trace use, main pipeline use, and other classification categories; and float-type, bucket-type, disk-type, and other classification categories), and, based on test results for a complete test spanning a plurality of cycles and on the classification category for each of the classification criteria to which each of the managed devices belongs, for creating analysis data indicating the relation between the malfunctioning frequency and the plurality of classification categories for each of the classification criteria for each of the managed devices, or analysis data indicating the malfunctioning frequency of each of the managed devices by the classification category for each of the classification criteria. According to the above embodiment, there is presented an analysis system having arithmetic means for creating, in accordance with a preset program and on the basis of test results for a complete test spanning a plurality of cycles and the prescribed classification category for individual devices to be managed as stored in storage means, analysis data indicating the malfunctioning frequency for each of the managed devices, the malfunctioning frequency for each of the managed devices by the classification category, and a relation between the malfunctioning frequency and the plurality of classification categories. It is also possible, however, to instead adopt an analysis system having input means for inputting a test result of a complete test and a classification category for each of a plurality of prescribed classification criteria to which individual devices to be managed belong; storage means for accumulating and storing the test result of each cycle of the complete test that has been input by the input means; and arithmetic means for creating, in accordance with a preset program, analysis data indicating the malfunctioning frequency for each of the managed devices, the malfunctioning frequency for each of the managed devices by the classification category, and a relation between the malfunctioning frequency and the plurality of classification categories. The analysis data is created on the basis of test results for the complete test spanning a plurality of cycles and the associated classification category for each of the classification criteria for each of the managed devices, as stored in the storage means. The present invention can be applied to the management or support of maintenance inspection operations involving a large group of devices typified by vapor traps, valves, and other devices installed in a plant.
045377405	claims	1. A device for obtaining a sample of gas bubbles entrained in a liquid which comprises: (a) a flow path for a portion of the liquid; (b) a filter within the flow path, said filter having holes of a diameter appropriate to require a pressure needed to force entrained gas bubbles through said filter holes to be greater than exists at said filter in said flow path due to the surface tension forces on said bubbles which opposes passage through said holes, said filter holes having a diameter ranging from about 10 .mu.m to 100 .mu.m; (c) a plenum disposed within said flow path to gather said gas bubbles which are prevented from passage through said filter, and (d) means for gathering and obtaining measurements on said gas bubbles as accumulated in said plenum. (a) a flow path for a portion of the liquid; (b) a filter within the flow path, said filter having holes of a diameter appropriate to prevent passage of entrained gas bubbles through said filter holes due to the surface tension forces on said bubbles which opposes passage through said holes, said filter holes having a diameter ranging from about 10 .mu.m to 100 .mu.m; (c) a plenum disposed within said flow path to gather said gas bubbles which are prevented from passage through said filter, and (d) means for gathering and obtaining measurements on said gas bubbles as are accumulated in said plenum. (a) a path for passage of a portion of coolant flow after passage through said fuel assembly; (b) a first filter in said path having holes adapted to pass coolant therethrough but sufficiently small to prevent passage of entrained fission gas bubbles, said filter holes having a diameter ranging from about 10 .mu.m to 100 .mu.m; (c) a plenum located within said path to gather fission gas bubbles which are denied passage through said first filter; (d) a second small filter located in said path, such that a portion of coolant flow through said first filter passes through said second small filter and second filter located adjacent to said plenum such that said second small filter becomes gas blanketed by fission gas bubbles which gather in said plenum when cladding failure occurs; and (e) means for monitoring coolant flow through said second small filter, such flow indicative of cladding failure since the gas blanketing of said second filter by fission gas then released reduces said flow. 2. A device for obtaining a sample of fission gas bubbles entrained in liquid metal coolant of a nuclear reactor which comprises: 3. The device of claim 2 wherein said coolant is liquid sodium. 4. The device of claim 2 wherein said filter holes are 100 .mu.m in diameter. 5. The device of claim 2 wherein said path has means for injection of an inert gas upstream of said filter. 6. A device for monitoring a nuclear fuel assembly for rod cladding failure and subsequent fission gas release which comprises:
051704188	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention. SOR light 101 produced by a synchrotron radiation device (not shown) goes along a beam line 103 and through a window material 107, provided on the beam line 103, and irradiates a mask 112 and a semiconductor wafer 111 accommodated in an exposure chamber 113. This irradiation contributes to processing the wafer 111 surface in accordance with a pattern of the mask 112. The beam line 103 is equipped with a shock wave delay tube 104, for retarding advancement of shock waves resulting from vacuum leakage, and a mirror chamber 105 for expanding the SOR light 101, disposed in this order. Provided between the mirror chamber 105 and the window material 107 is a pressure sensor 106, and provided between the synchrotron radiation device and the delay tube 104 is an emergency cutoff valve 102 which is operable in response to the detection by the pressure sensor 106. The mask 112 and the wafer 111 accommodated in the exposure chamber 113 can be replaced by any one of masks 115 accommodated in a mask pre-chamber 116 and any one of wafers 108 accommodated in a wafer pre-chamber 109, respectively, with the cooperation of gate valves 114 and 110, respectively. If the window material 107 is broken as a result of leakage in the beam line 103 or in the exposure chamber 113, like the FIG. 5 case, in response, the pressure detected by the pressure sensor 106 increases and the emergency cutoff valve 102 closes to block entry of atmospheric gas into the synchrotron radiation source device. The beam line of the present embodiment is further equipped with a pressure sensor (pressure detecting means) 117 for detecting the pressure in the exposure chamber 113; a cutoff valve 118 effective to intercept the mirror chamber 105 and the window 107 from each other; a bypass 119 for defining a bypass, communicating through a communication valve 120 the exposure chamber with a portion between the cutoff valve 118 and the window material 107; and a vacuum pump (vacuum evacuating means) 123 for vacuum evacuating a portion between the window 107 and the cutoff valve 118. The vacuum pump 123 is communicated with the aforementioned portion of the beam line by means of a conduit having a pump valve (switch valve) 122. The pressure sensor 117 is provided between the window material 107 and the exposure chamber 118, while the pressure sensor 122 is provided between the window material 107 and the cutoff valve 118. The exposure chamber 113 is equipped with a vacuum pump 125 for vacuum evacuation of the chamber interior through a pump valve 126. Outside the beam line 103 and the exposure chamber 113 of the structure described above, there is provided a controller 121 for controlling the operations of the cutoff valve 118 and the communication valve 120 as well as the operations of the pump valves 124 and 126, in response to the pressure as detected by the pressure sensor 117 or 122. The wafer 111 placed in the exposure chamber 113 is exposed with the SOR light 101, having passed through the beam line 103 and the window material 107 and having been partially blocked by the mask 112. During this exposure process, heat is generated in the mask due to irradiation with the SOR light 101. In consideration thereof, the exposure chamber 113 is filled with a reduced-pressure gas ambience (e.g. He gas of 150 Torr), reduced to an order assuring necessary heat conduction. The window material 107 should have good transmissivity to the SOR light 101, and it may be a thin beryllium material (10-20 micron thickness). The inside pressure P.sub.S (e.g. 150 Torr) of the exposure chamber 113 is so set as to be lower than the withstand pressure P.sub.L of the window material 107 of the aforementioned thickness. Like the FIG. 5 example, for replacement of the mask 112 or the wafer 111 by any one of masks 115 accommodated in a mask pre-chamber 116 or any one of wafers 108 accommodated in a wafer pre-chamber 109, the wafer pre-chamber 109 or the mask pre-chamber 116 is maintained in a state (load-locked state) filled with an ambience similar to that in the exposure chamber 113. While not shown in the drawing, each of the exposure chamber 113, the wafer pre-chamber 109 and the mask pre-chamber 106 is equipped with vacuum evacuating means and gas supplying means for accomplishing the above-described inside ambience, with pressure control. Only illustrated in FIG. 1 is the vacuum pump (vacuum evacuating means) 125 communicated with the exposure chamber 113 by way of a conduit having the pump valve (switch valve) 126. In normal exposure operation, the emergency cutoff valve 102 and the cutoff valve 118 as well as the pump valve 122 are all maintained open, while the communication valve 120 is kept closed. Thus, also the vacuum pump 123 serves to maintain the vacuum in the beam line 103. If leakage occurs in the beam line during the exposure operation, the leakage is detected by the pressure sensor 106 as in the FIG. 5 example, and the emergency cutoff valve 102 is closed for protection of the synchrotron radiation device. The leakage detection in regard to the exposure chamber 113 as well as the protection of the window material 107 are made under the control of the controller 121. FIG. 2A is a flow chart showing the operation of the controller 121 during the exposure operation. In the exposure operation, the controller 121 continuously monitors (step S1) whether the pressure P in the exposure chamber 113 as detected by the pressure sensor 117 is higher than a predetermined pressure P.sub.O (P.sub.S <P.sub.O <P.sub.L). If a failure in load-locking occurs in the mask pre-chamber 106 or in the wafer pre-chamber 109 or a failure in pressure adjustment occurs in the exposure chamber 113 and, as a result, the pressure P becomes higher than the predetermined pressure P.sub.O, then the cutoff valve 118 as well as the pump valves 124 and 126 are closed (step S2) and, subsequently, the communication valve 120 is opened (step S3). Since the cutoff valve 118 is closed before the pressure P reaches the withstand pressure P.sub.L of the window material 107, at least the scattering of fractions of the window material 107 at an upstream portion of the beam line can be prevented. Also, since the communication valve 122 is opened before the pressure P reaches the withstand pressure P.sub.L of the window material 107, it is possible to effectively prevent application of pressure to the window material and, thus, to avoid breakage of the window material 107. FIG. 2B is a flow chart showing the operation of the controller 121 after the leakage in the exposure chamber is fixed so that the exposure operation is going to be re-started. At the re-start, the controller 121 opens the pump valve 126 (step S4) and causes the vacuum pump 125 to effect the vacuum evacuation of the exposure chamber 113. This operation continues until the pressure P detectable by the pressure sensor 117 becomes lower than a predetermined pressure P.sub.A (e.g. about 10.sup.-3 Torr) (step S5). If P<P.sub.A is satisfied, the communication valve 120 is closed (step S6). Then, the pump valve 124 is opened to start the introduction of He gas into the exposure chamber 113 (step S7). After this, whether the pressure P as detected by the pressure sensor 122 is lower than a vacuum level (e.g. 10.sup.-7 Torr) required in the beam line 103 for the exposure process, is checked (step S8). Further, whether the inside pressure of the exposure chamber 113 is at the predetermined level for the exposure process so that it allows the exposure process, is checked (step S9). After this, the cutoff valve 118 is opened (step S10). With the above-described operations, it is possible to prevent entry of He gas into the beam line 103 and, thus, to re-start the exposure process smoothly. FIG. 3 shows a second embodiment of the present invention. This embodiment corresponds to a simplified form of the FIG. 1 embodiment and an additional cutoff valve 301 is provided. Corresponding elements are denoted by the same reference numerals, and explanation of them is now omitted. In the present embodiment, the cutoff valve 118, the bypass 119, the communication valve 120, the pump valve 122 and the vacuum pump 123 of the FIG. 1 embodiment are omitted. At a position in the exposure chamber 113 and adjacent to the window material 107 and at such position interposing the pressure sensor 117 between it and the window material 107, the cutoff valve 301 is provided (the operation of the cutoff valve 301 is controlled by the controller 121). In FIG. 3, the vacuum pump 125 and the pump valve 126 provided in the exposure chamber 113 are not illustrated. When the pressure P detected by the pressure sensor 117 becomes higher than a predetermined pressure P.sub.O, the controller 121 closes the cutoff valve 301. This prevents application of additional pressure to the window material 107 and, thus, avoids breakage of the window material 107. FIG. 4 shows a third embodiment of the present invention. This embodiment corresponds to a combined form of the first and second embodiments, wherein, to the first embodiment, a cutoff valve 301 is added which valve is provided between the exposure chamber 113 and the portion of the bypass 119 communicating with the exposure chamber 113. Thus, similar elements as of the first and second embodiments are denoted by the same reference numerals as of FIGS. 1 and 3, and explanation of them is now omitted. The operation of the present embodiment is essentially the same as that shown in FIGS. 2A and 2B, and the opening/closing motion of the cutoff valve 118 and the opening/closing motion of the cutoff valve 301 are operationally associated with each other. This assures that, after the cutoff valves 118 and 301 are closed, no stress is applied to the window material as a result of the leakage. Thus, the level of safety is enhanced significantly. While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.
040428281	claims	1. A rack for spent nuclear fuel elements comprising: a. a frame; b. enclosures for containing respectively spent nuclear fuel elements, said enclosures being supported by said frame in an upright position; and c. a support for each of said enclosures resting on a supporting surface and disposed below the fuel element contained by the associated enclosure for supporting the load of the fuel element while the associated enclosure retains the fuel element in an upright position. a. a base on which rests an associated fuel element; and b. legs connected to its associated base and disposed on a supporting surface for supporting the associated base. a. a frame; b. enclosures for containing respectively spent nuclear fuel elements, said enclosures being supported by said frame in an upright position; and c. a support for each of said enclosures resting on a supporting surface and disposed below the fuel element contained by the associated enclosure for supporting the load of the fuel element while the associated enclosure retains the fuel element in an upright position, each of said supports comprising: a. a second base resting on the supporting base; and b. a swivel joint with a stationary part fixed to said second base and a movable part connected to said first base for movement therewith. a. a frame; b. enclosures for containing respectively spent nuclear fuel elements, said enclosures being supported by said frame in an upright position; c. a support for each of said enclosures resting on a supporting surface and disposed below the fuel element contained by the associated enclosure for supporting the load of the fuel element while the associated enclosure retains the fuel element in an upright position, each of said supports including means for self-alignment to accommodate an uneven supporting surface while supporting the fuel element in the upright position; and d. legs resting on a support surface and disposed below said frame in the vicinity of the corners thereof for supporting said frame, each of said legs for said frame including means for adjusting the height thereof. a. a frame; b. enclosures for containing respectively spent fuel elements, said enclosures being supported by said frame in an upright position, said enclosures being fixed to said frame; c. a support for each of said enclosures resting on a supporting surface and disposed below the fuel element contained by the associated enclosure for supporting the load of the fuel element, while the associated enclosure retains the fuel element in an upright position; and d. a rack-to-rack connector attached to said frame for securing an adjacent frame thereto, said connector comprising: a. a frame; b. enclosures for containing respectively spent fuel elements, said enclosures being supported by said frame in an upright position, said enclosures being fixed to said frame; c. a support for each of said enclosures resting on a supporting surface and disposed below the fuel element contained by the associated disclosure for supporting the load of the fuel element, while the associated enclosure retains the fuel element in an upright position; and d. a rack-to-rack connector attached to said frame for securing an adjacent frame thereto, said connector comprising: f. a bolt extending through said bore and beyond said body; and g. a clamp with a threaded opening aligned with the bore of said body, said clamp being formed with wings extending toward the free ends of said first and second connector arms, said clamp being in threaded engagement with said bolt and being adapted to be drawn toward said first and second connector arms and said body by said bolt, said frame being gripped between the space defined by said first connector arm, said first spacer member, said body and said clamp, said second connector arm, said second spacer member, said body and said clamp being arranged to grip the frame of an adjacent rack. 2. A rack as claimed in claim 1 wherein said enclosures are fixed to said frame. 3. A rack as claimed in claim 1 wherein each of said supports comprises: 4. A rack as claimed in claim 3 wherein each base is attached to its associated enclosure. 5. A rack as claimed in claim 4 and comprising legs disposed below said frame in the vicinity of the corners thereof for supporting said frame. 6. A rack as claimed in claim 5 wherein each of said enclosures includes a flared opening at the top thereof to guide the entry of the nuclear fuel element contained therein. 7. A rack as claimed in claim 1 wherein each of said supports includes means for self-alignment to accommodte an uneven supporting surface while supporting the fuel element in the upright position. 8. A rack for spent nuclear fuel elements comprising: 9. A rack as claimed in claim 8 wherein said swivel means comprises: 10. A rack as claimed in claim 7 and comprising legs resting on a supporting surface and disposed below said frame in the vicinity of the corners thereof for supporting said frame. 11. A rack for spent nuclear fuel elements comprising: 12. A rack as claimed in claim 7 wherein each of said enclosures includes a flared opening at the top thereof to guide the entry of the nuclear fuel element contained therein. 13. A rack as claimed in claim 2 and comprising a rack-to-rack connector attached to said frame for securing an adjacent frame thereto. 14. A rack for spent nuclear fuel elements comprising: 15. A rack for spent nuclear fuel elements comprising: 16. A rack as claimed in claim 7 wherin each of said enclosures is bolted to said frame.
	abstract	An improved method and apparatus for extracting and handling samples for STEM analysis. Preferred embodiments of the present invention make use of a micromanipulator and a hollow microprobe probe using vacuum pressure to adhere the microprobe tip to the sample. By applying a small vacuum pressure to the lamella through the microprobe tip, the lamella can be held more securely and its placement controlled more accurately than by using electrostatic force alone. By using a probe having a beveled tip and which can also be rotated around its long axis, the extracted sample can be placed down flat on a sample holder. This allows sample placement and orientation to be precisely controlled, thus greatly increasing predictability of analysis and throughput.

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