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1695_3 | Facial support and aesthetics
When an individual's mouth is at rest, the teeth in the opposing jaws are nearly touching; there is what is referred to as a "freeway space" of roughly 2–3 mm. However, this distance is partially maintained as a result of the teeth limiting any further closure past the point of maximum intercuspidation. When there are no teeth present in the mouth, the natural vertical dimension of occlusion is lost and the mouth has a tendency to overclose. This causes the cheeks to exhibit a "sunken-in" appearance and wrinkle lines to form at the commissures. Additionally, the anterior teeth, when present, serve to properly support the lips and provide for certain aesthetic features, such as an acute nasiolabial angle.
Loss of muscle tone and skin elasticity due to old age, when most individuals begin to experience edentulism, tend to further exacerbate this condition. |
1695_4 | The tongue, which consists of a very dynamic group of muscles, tends to fill the space it is allowed, and in the absence of teeth, will broaden out. This makes it initially difficult to fabricate both complete dentures and removable partial dentures for patients exhibiting complete and partial edentulism, respectively; however, once the space is "taken back" by the prosthetic teeth, the tongue will return to a narrower body. |
1695_5 | Vertical dimension of occlusion
As stated, the position of maximal closure in the presence of teeth is referred to as maximum intercuspidation, and the vertical jaw relationship in this position is referred to as the vertical dimension of occlusion. With the loss of teeth, there is a decrease in this vertical dimension, as the mouth is allowed to overclose when there are no teeth present to block further upward movement of the mandible towards the maxilla. This may contribute, as explained above, to a sunken-in appearance of the cheeks, because there is now "too much" cheek than is needed to extend from the maxilla to the mandible when in an overclosed position. If this situation is left untreated for many years, the muscles and tendons of the mandible and the TMJ may manifest with altered tone and elasticity. |
1695_6 | Pronunciation
The teeth play a major role in speech. Some letter sounds require the lips and/or tongue to make contact with teeth for proper pronunciation of the sound, and lack of teeth will obviously affect the way in which an edentulous individual can pronounce these sounds.
For example, the consonant sounds of the English language s, z, j, and x are achieved with tooth-to-tooth contact; d, n, l, t, and th are achieved with tongue-to-tooth contact; the fricatives f and v are achieved through lip-to-tooth contact. The edentulous individual finds these sounds very difficult to enunciate properly.
Preservation of alveolar ridge height |
1695_7 | The alveolar ridges are columns of bone that surround and anchor the teeth and run the entire length, mesiodistally, of both the maxillary and mandibular dental arches. The alveolar bone is unique in that it exists for the sake of the teeth that it retains; when the teeth are absent, the bone slowly resorbs. The maxilla resorbs in a superioposterior direction, and the mandible resorbs in an inferioanterior direction, thus eventually converting an individual's occlusal scheme from a Class I to a Class III. Loss of teeth alters the form of the alveolar bone in 91% of cases. |
1695_8 | In addition to this resorption of bone in the vertical and anterioposterior dimensions, the alveolus also resorbs faciolingually, thus diminishing the width of the ridge. What initially began as a sort of tall, broad, bell curve-shaped ridge (in the faciolingual dimension) eventually becomes a short, narrow, stumpy sort of what doesn't even appear to be a ridge. Resorption is exacerbated by pressure on the bone; thus, long-term complete denture wearers will experience more drastic reductions to their ridges than non-denture wearers. Those individuals who do wear dentures can decrease the amount of bone loss by retaining some tooth roots in the form of overdenture abutments or have implants placed. Note that the depiction above shows a very excessive change and that this many take many years of denture wear to achieve. |
1695_9 | Ridge resorption may also alter the form of the ridges to less predictable shapes, such as bulbous ridges with undercuts or even sharp, thin, knife-edged ridges, depending on the many possible factors that influenced the resorption. |
1695_10 | Bone loss with missing teeth, partials and complete dentures is progressive. According to Wolff's law, bone is stimulated, strengthened and continually renewed directly by a tooth or an implant. Teeth and implants provide this direct stimulation which develops stronger bone around them.
A 1970 research study of 1012 patients by Jozewicz showed denture wearers had a significantly higher rate of bone loss. Tallgren's 25-year study in 1972 also showed denture wearers have continued bone loss over the years. The biting force on the gum tissue irritates the bone and it melts away with a decrease in volume and density. Carlsson's 1967 study showed a dramatic bone loss during the first year after a tooth extraction which continues over the years, even without a denture or partial on it. |
1695_11 | The longer people are missing teeth, wear dentures or partials, the less bone they have in their jaws. This may result in decreased ability to chew food well, a decreased quality of life, social insecurity and decreasing esthetics because of a collapsing of the lower third of their face.
The bone loss also results in a significant decrease in chewing force, prompting many denture and partial wearers to avoid certain kinds of food. Food collecting under the appliance takes their enjoyment out of eating so they make their grocery and restaurant choices by what they can eat. There are several reports that correlate the quality and length of peoples lives with their ability to chew. |
1695_12 | Dental implant studies from 1977 by Branemark and countless others show dental implants stop this progressive loss and stabilize the bone over the long term. Implanted teeth provide a stable, effective tooth replacement that feels natural. They also provide an improved ability to chew comfortably and for those missing many teeth an improved sense of well being. Dental implants have become the standard for replacing missing teeth in dentistry. |
1695_13 | Masticatory efficiency |
1695_14 | Physiologically, teeth provide for greater chewing ability. They allow us to masticate food thoroughly, increasing the surface area necessary to allow for the enzymes present in the saliva, as well as in the stomach and intestines, to digest our food. Chewing also allows food to be prepared into small boli that are more readily swallowed than haphazard chunks of considerable size. For those who are even partially endentulous, it may become extremely difficult to chew food efficiently enough to swallow comfortably, although this is entirely dependent upon which teeth are lost. When an individual loses enough posterior teeth to make it difficult to chew, he or she may need to cut their food into very small pieces and learn how to make use of their anterior teeth to chew. If enough posterior teeth are missing, this will not only affect their chewing abilities, but also their occlusion; posterior teeth, in a mutually protected occlusion, help to protect the anterior teeth and the |
1695_15 | vertical dimension of occlusion and, when missing, the anterior teeth begin to bear a greater amount of force than they are structurally prepared for. Thus, loss of posterior teeth will cause the anterior teeth to splay. This can be prevented by obtaining dental prostheses, such as removable partial dentures, bridges or implant-supported crowns. In addition to reestablishing a protected occlusion, these prostheses can greatly improve one's chewing abilities. |
1695_16 | As a consequence of a lack of certain nutrition due to altered eating habits, various health problems can occur, from the mild to the extreme. Lack of certain vitamins (A, E and C) and low levels of riboflavin and thiamin can produce a variety of conditions, ranging from constipation, weight loss, arthritis and rheumatism. There are more serious conditions such as heart disease and Parkinson's disease and even to the extreme, certain types of Cancer. Treatments include changing approaches to eating such as cutting food in advance to make eating easier and less likely to avoid as well as consumer health products such as multivitamins and multi-minerals specifically designed to support the nutritional issues experienced by denture wearers. |
1695_17 | Numerous studies linking edentulism with instances of disease and medical conditions have been reported. In a cross-sectional study, Hamasha and others found significant differences between edentulous and dentate individuals with respect to rates of atherosclerotic vascular disease, heart failure, ischemic heart disease and joint disease.
Cause
Edentulism is a condition which can have multiple causes. In exceedingly rare cases, toothlessness may result from the teeth not developing in the first place (anodontia). However, in most cases it is as a result of permanent tooth extraction in adulthood. This may or may not be due to dental caries, periodontal disease (gum disease), trauma or other pathology of the face and mouth (i.e. cysts, tumours). In those under 45 years of age, dental caries is considered to be the main cause of toothlessness, whereas periodontal disease is the primary cause of tooth loss in older age groups. |
1695_18 | Replacing missing teeth
There are three main ways in which missing teeth can be replaced: |
1695_19 | Bridges: Used to replace one or more missing teeth. False teeth are supported by the remaining, adjacent natural teeth.
Advantages:
They are fixed, they do not require removal on a frequent basis. Therefore, they are easily maintained.
Can be cleaned by normal brushing procedures.
Unlike dentures, they do not require skill in their use. They will not move about.
Disadvantages:
They generally require the preparation of adjacent teeth. This is destructive and not required for the placement of a denture.
They have a higher rate of failure than either Dentures or Implants.
Dentures: False teeth are mounted onto an acrylic base. These may be partial (to replace some missing teeth) or complete (where all the natural teeth are missing). Dentures may be removable, or fixed in the mouth by dental implants.
Advantages:
This is the least expensive option for the replacement of teeth.
The least invasive, no surgery needed (usually).
Disadvantages: |
1695_20 | Quite often rely solely on the mucosa for support, do not tend to be as stable as the other options.
Very difficult to keep clean and can exacerbate any oral hygiene issues.
They are difficult to learn to use. Quite often require complex muscular control to hold them in place.
Not as efficient as other options. Foods such as apples and nuts will often have to be avoided. |
1695_21 | Dental Implants: To replace a single tooth, a screw (the implant) is placed into the jaw bone, which a false tooth is screwed onto. Implants can also be used to support bridges or dentures.
Advantages:
They are much more realistic than the other options. They have similar efficiency and aesthetics to an actual tooth.
They do not require the destruction of the adjacent teeth like bridges.
They last 5-8 times longer than both bridges and dentures. Despite the initial higher cost, it pays off in the long term.
Much easier to maintain, with oral hygiene procedures being rather similar to an actual tooth.
Disadvantages:
Cost: they are very expensive. A single implant will cost between £2000-3000 on average.
Surgery: Their placement requires quite invasive surgery. With surgery comes risks (e.g. infection, swelling, bleeding). |
1695_22 | Replacement: The actual implant itself rarely requires replacement, but the actual abutment, or tooth sitting on top of the implant will. This needs replacing on average every 10–15 years.
Time: Once an implant has been placed, the tooth replacement does not occur immediately. Implants take time for bone integration. The majority require 3 to 6 months before the final restoration is placed. |
1695_23 | Clinical classification
A classification system has been developed by the American College of Prosthodontists. The classification are based on diagnostic findings, which is used to help practitioners determine appropriate treatments for patients.
The diagnostic criteria used to classify edentulism are:
Location and extent of the edentulous areas
Condition of abutment teeth
Occlusal scheme
Residual ridge
There are four categories which are Class I, II, III and IV.
Class I: Minimally compromised
This class is most likely to be successfully treated with complete dentures. The characteristics include:
Residual bone height of 21mm or more measured at the lowest vertical height of the mandible shown on a panoramic radiograph.
Residual ridge morphology resists horizontal and vertical movement of the denture base
Location of muscle attachments that arc conducive to denture base stability and retention
Class I maxillomandibular relationship.
Class II: Moderately compromised |
1695_24 | This class is distinguished by the continued degradation of the denture‐supporting anatomy. It is also characterised by specific patient management and lifestyle considerations as well as systemic disease interactions. Characteristics include:
Residual bone height of 16 to 20mrn measured at the lowest vertical height of the mandible on a panoramic radiograph.
Residual ridge morphology that does not show horizontal and vertical movement of the denture base.
Location of muscle attachments with limited influence on denture base stability and retention.
Class I maxillomandibular relationship.
Minor modifiers, psychosocial considerations, mild systemic disease with oral manifestaion.
Class III: Substantially compromised
This classification level is where surgical revision of supporting structures is needed to allow for adequate prosthodontic function. |
1695_25 | Residual alveolar bone height of 11 to 15mm measured at the least vertical height of the mandible on a panoramic radiograph.
Residual ridge morphology has minimum influence to resist horizontal or vertical movement of the denture base.
Location of muscle attachments with moderate influence on denture base stability and retention.
Class I, II or III maxillomandibular relationship.
The conditions that need preprosthetic surgery include:
minor soft tissue procedures
minor hard tissue procedures including alveoloplasty
simple implant placement, no augmentation required
multiple extractions leading to complete edentulism for immediate denture placement.
Class IV: Severely compromised |
1695_26 | This classification level depicts the most debilitated edentulous condition. Surgical reconstruction is almost always indicated but cannot always be accomplished because of the patient's health, preferences, dental history, and financial considerations. When surgical revision is not an option, prosthodontic techniques of a specialized nature must be used to achieve an adequate treatment outcome.
Residual vertical bone height of 10mm or less measured at the least vertical height of the mandible on a panoramic radiograph.
Residual ridge offers no resistance to horizontal or vertical movement.
Muscle attachment location that can be expected to have significant influence on denture base stability and retention.
Class I, II, or III maxillomandibular relationships.
History of paresthesia or dysesthesia.
Major conditions requiring preprosthetic surgery |
1695_27 | complex implant placement, augmentation required
surgical correction of dentofacial deformities
hard tissue augmentation required
major soft tissue revision required, i.e., vestibular extensions with or without soft tissue grafting.
Epidemiology
Edentulism affects approximately 158 million people globally as of 2010 (2.3% of the population). It is more common in women at 2.7% compared to the male rate of 1.9%. |
1695_28 | A cross-sectional analysis of data from the Survey of Health, Ageing and Retirement in Europe (SHARE) from 14 European countries (Austria, Belgium, Czech Republic, Denmark, Estonia, France, Germany, Italy, Luxembourg, the Netherlands, Slovenia, Spain, Sweden, and Switzerland) and Israel showed substantial variation in the age-standardized mean numbers of natural teeth amongst people aged 50 years and older, ranging from 14.3 teeth (Estonia) to 24.5 teeth (Sweden). The oral health goal of retaining at least 20 teeth at age 80 years was achieved by 25% of the population or less in most countries. A target concerning edentulism (≤15% in population aged 65–74 years) was reached in Sweden, Switzerland, Denmark, France, and Germany. Tooth replacement practices varied especially for a number of up to five missing teeth which were more likely to be replaced in Austria, Germany, Luxembourg, and Switzerland than in Israel, Denmark, Estonia, Spain, and Sweden. |
1695_29 | The prevalence of Kennedy Class III partial denture was predominant among younger population of 21-30 year and 31–40 years, whereas in group III between 41 and 50 years Class I was predominant. It can be stated that the need for prosthodontics care is expected to increase with age, and hence, more efforts should be made for improving dental education and motivation among patients.
Edentulism occurs more often in people from the lower end of the socioeconomic scale.
Society and culture
It is estimated that tooth loss results in worldwide productivity losses in the size of about US$63 billion yearly.
References
Dental anatomy
Teeth
Acquired tooth pathology |
1696_0 | Suburban Hostage was an American punk rock band from Denver, Colorado, United States, formed in 2004. The current lineup consists of Ross Swirling (vocals), Felipe Patino (guitar), Bret Ahroon (bass guitar, back-up vocals), Cody Bennett (guitar, back-up vocals), and Ruben Patino (drums). The band is currently recording with Ridiculous Records an independent punk rock record label based in Denver. Suburban Hostage has released one studio album. |
1696_1 | History
In 1998, two young brothers named Felipe and Ruben moved to Colorado from their native Lima, Peru to pursue their musical dreams in The United States. Before leaving Peru, Ruben had been playing in a band named Futuro Incierto, well known throughout Latin America for their smooth hard-core punk rock music. Early in 2004 the brothers met a young guitarist named T.J. Petty and formed a hardcore punk rock band named Suburban Hostage.
The band began playing small shows Denver bars and clubs and gaining some local notoriety. In 2005, Ross Swirling left the band Action Shot where he played Alto Sax to become the lead singer of Suburban Hostage. At the same time, Felipe and Ruben asked a young bass guitar player by the name of Bret Ahroon to joint the band. He agreed, and the line-up was set to record the band's first studio album. |
1696_2 | In 2006, the band began work on A Sorry State, its first studio album. It was recorded entirely in a home-made studio located in the basement of Ruben's house. Knowing the album needed some "fine touches" put on it before release, Bret convinced the band to have the album mixed and mastered at The Blasting Room, a famous punk rock recording studio located in Fort Collins, Colorado and owned by Descendents drummer, Bill Stevenson. |
1696_3 | In 2008, Felipe took a break from the band and from Denver for school related reasons. This left Suburban Hostage without a lead guitarist at almost the same time a tour was booked in support of A Sorry State. The band was rescued by highly talented Berklee grad and guitar teacher, Jeff Solohub. It was understood that he would only be filling in for Felipe while the band was on tour. During the summer of 2008 Suburban Hostage played a slew of shows around Colorado and the West Coast with Jeff in the lineup and it was decided that, when Felipe returned, he would be a permanent member. Shortly after the decision to add Jeff to the band, T.J. left to start a new band called “The Sunday Strippers.” |
1696_4 | Growing reputation
Suburban Hostage dove head first into the Denver punk rock scene before ever recording a proper album, relying entirely on their stunning live show, along with T-shirt and ticket sales, to keep growing as a band. Their unique hard-core punk rock style and inviting stage presence caught the attention of local promoters and fans alike. In a short amount of time, they started sharing stages around Denver with local favorites like Red Stinger, Frontside Five, and Boldtype as well as national touring acts such as; A Wilhelm Scream, The Unseen, Ignite, Teenage Bottlerocket, Agent Orange and Only Crime. The band has continued working on a lot of new music while songs from their upcoming EP Unified Theory of Critical Thinking can be heard in their live sets. |
1696_5 | A Sorry State (2006)
A Sorry State was recorded over the course of 2006 and was tracked in the basement of drummer Ruben Patino's house. The album was mixed and mastered by Andrew Berlin at The Blasting Room in Fort Collins Colorado. A Sorry State became available in stores and the iTunes Music Store the same month. Current distribution of this album is being handled by Ridiculous Records.
Unified Theory of Critical Thinking (2009)
Recording began on a follow up to A Sorry State in early 2009 at The Blasting Room in Fort Collins, Colorado where Felipe Patino found work upon returning from school in Florida. The EP titled; Unified Theory of Critical Thinking is the first to feature the band's current lineup on a recorded album. Felipe Patino tracked and mixed the new EP which the band then brought to Jason Livermore for mastering. Unified Theory of Critical Thinking has been set for a September, 2009 release date and is slated to be the first release from Ridiculous Records. |
1696_6 | Ridiculous Records
After years of being free of major record labels and independent record labels alike, Ross Swirling, singer for Suburban Hostage, made a decision to start his own label. Ridiculous Records, an LLC, was set up initially to release the forthcoming Suburban Hostage EP and hopes to help bolster the Denver music scene by working with other local bands and artists.
There has been favorable reaction from musicians and fans alike to the news of a new record label in Denver. Ross is following in the footsteps of other musicians turned label owners such as Fat Mike from Fat Wreck Chords, Joe Sib and Bill Armstrong from Side One Dummy Records, and Mike Park from Asian Man Records who have successfully started their own labels and supported the Punk Rock community by releasing quality albums from bands they enjoy.
Influences
Suburban Hostage is strongly influenced by the music of Propagandhi, NOFX, Minor Threat and Bad Religion. |
1696_7 | Current members
Ross Swirling - Vocals
Felipe Patino - Lead Guitar
Bret Ahroon - Bass Guitar, Back-up Vocals
Cody Bennett - Guitar, Back-up Vocals
Ruben Patino - Drums
Former members
Jeff Solohub - Guitar, Back-up Vocals
T.J. Petty - Guitar, Back-up Vocals
Discography
Sorry State (2007)
Unified Theory of Critical Thinking (EP) (September, 2009)
References
Official Suburban Hostage Website
Pure Volume
Colorado Daily
Denver Decider
Soda Jerk Presents
Punk rock groups from Colorado
Musical groups established in 2004 |
1697_0 | Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission.
Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing and sustaining nuclear fission. The three most relevant fissile isotopes are uranium-233, uranium-235 and plutonium-239. When the unstable nuclei of these atoms are hit by a slow-moving neutron, they split, creating two daughter nuclei and two or three more neutrons. These neutrons then go on to split more nuclei. This creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon.
The processes involved in mining, refining, purifying, using, and disposing of nuclear fuel are collectively known as the nuclear fuel cycle. |
1697_1 | Not all types of nuclear fuels create power from nuclear fission; plutonium-238 and some other elements are used to produce small amounts of nuclear power by radioactive decay in radioisotope thermoelectric generators and other types of atomic batteries.
Nuclear fuel has the highest energy density of all practical fuel sources.
Oxide fuel
For fission reactors, the fuel (typically based on uranium) is usually based on the metal oxide; the oxides are used rather than the metals themselves because the oxide melting point is much higher than that of the metal and because it cannot burn, being already in the oxidized state.
Uranium dioxide
Uranium dioxide is a black semiconducting solid. It can be made by heating uranyl nitrate to form
UO2(NO3)2.6H2O-> UO3 + NO2 + 1/2O2 + 6H2O(g) |
1697_2 | This is then converted by heating with hydrogen to form UO2. It can be made from enriched uranium hexafluoride by reacting with ammonia to form a solid called ammonium diuranate, (NH4)2U2O7. This is then heated (calcined) to form and U3O8 which is then converted by heating with hydrogen or ammonia to form UO2.
The UO2 is mixed with an organic binder and pressed into pellets, these pellets are then fired at a much higher temperature (in H2/Ar) to sinter the solid. The aim is to form a dense solid which has few pores.
The thermal conductivity of uranium dioxide is very low compared with that of zirconium metal, and it goes down as the temperature goes up.
Corrosion of uranium dioxide in water is controlled by similar electrochemical processes to the galvanic corrosion of a metal surface.
MOX |
1697_3 | Mixed oxide, or MOX fuel, is a blend of plutonium and natural or depleted uranium which behaves similarly (though not identically) to the enriched uranium feed for which most nuclear reactors were designed. MOX fuel is an alternative to low enriched uranium (LEU) fuel used in the light water reactors which predominate nuclear power generation.
Some concern has been expressed that used MOX cores will introduce new disposal challenges, though MOX is itself a means to dispose of surplus plutonium by transmutation.
Reprocessing of commercial nuclear fuel to make MOX was done in the Sellafield MOX Plant (England). As of 2015, MOX fuel is made in France (see Marcoule Nuclear Site), and to a lesser extent in Russia (see Mining and Chemical Combine), India and Japan. China plans to develop fast breeder reactors (see CEFR) and reprocessing. |
1697_4 | The Global Nuclear Energy Partnership, was a U.S. proposal in the George W. Bush Administration to form an international partnership to see spent nuclear fuel reprocessed in a way that renders the plutonium in it usable for nuclear fuel but not for nuclear weapons. Reprocessing of spent commercial-reactor nuclear fuel has not been permitted in the United States due to nonproliferation considerations. All of the other reprocessing nations have long had nuclear weapons from military-focused "research"-reactor fuels except for Japan. Normally, with the fuel being changed every three years or so, about half of the Pu-239 is 'burned' in the reactor, providing about one third of the total energy. It behaves like U-235 and its fission releases a similar amount of energy. The higher the burn-up, the more plutonium in the spent fuel, but the lower the fraction of fissile plutonium. Typically about one percent of the used fuel discharged from a reactor is plutonium, and some two thirds of |
1697_5 | this is fissile (c. 50% Pu-239, 15% Pu-241). Worldwide, some 70 tonnes of plutonium contained in used fuel is removed when refueling reactors each year. |
1697_6 | Metal fuel
Metal fuels have the advantage of a much higher heat conductivity than oxide fuels but cannot survive equally high temperatures. Metal fuels have a long history of use, stretching from the Clementine reactor in 1946 to many test and research reactors. Metal fuels have the potential for the highest fissile atom density. Metal fuels are normally alloyed, but some metal fuels have been made with pure uranium metal. Uranium alloys that have been used include uranium aluminum, uranium zirconium, uranium silicon, uranium molybdenum, and uranium zirconium hydride (UZrH). Any of the aforementioned fuels can be made with plutonium and other actinides as part of a closed nuclear fuel cycle. Metal fuels have been used in water reactors and liquid metal fast breeder reactors, such as EBR-II. |
1697_7 | TRIGA fuel
TRIGA fuel is used in TRIGA (Training, Research, Isotopes, General Atomics) reactors.
The TRIGA reactor uses UZrH fuel, which has a prompt negative fuel temperature coefficient of reactivity, meaning that as the temperature of the core increases, the reactivity decreases—so it is highly unlikely for a meltdown to occur. Most cores that use this fuel are "high leakage" cores where the excess leaked neutrons can be utilized for research. That is, they can be used as a neutron source. TRIGA fuel was originally designed to use highly enriched uranium, however in 1978 the U.S. Department of Energy launched its Reduced Enrichment for Research Test Reactors program, which promoted reactor conversion to low-enriched uranium fuel. A total of 35 TRIGA reactors have been installed at locations across the US. A further 35 reactors have been installed in other countries. |
1697_8 | Actinide fuel
In a fast neutron reactor, the minor actinides produced by neutron capture of uranium and plutonium can be used as fuel. Metal actinide fuel is typically an alloy of zirconium, uranium, plutonium, and minor actinides. It can be made inherently safe as thermal expansion of the metal alloy will increase neutron leakage.
Molten plutonium
Molten plutonium, alloyed with other metals to lower its melting point and encapsulated in tantalum, was tested in two experimental reactors, LAMPRE I and LAMPRE II, at Los Alamos National Laboratory in the 1960s. "LAMPRE experienced three separate fuel failures during operation."
Non-oxide ceramic fuels
Ceramic fuels other than oxides have the advantage of high heat conductivities and melting points, but they are more prone to swelling than oxide fuels and are not understood as well.
Uranium nitride |
1697_9 | This is often the fuel of choice for reactor designs that NASA produces, one advantage is that UN has a better thermal conductivity than UO2. Uranium nitride has a very high melting point. This fuel has the disadvantage that unless 15N was used (in place of the more common 14N) that a large amount of 14C would be generated from the nitrogen by the (n,p) reaction. As the nitrogen required for such a fuel would be so expensive it is likely that the fuel would have to be reprocessed by pyroprocessing to enable the 15N to be recovered. It is likely that if the fuel was processed and dissolved in nitric acid that the nitrogen enriched with 15N would be diluted with the common 14N. Fluoride volatility is a method of reprocessing that does not rely on nitric acid, but it has only been demonstrated in relatively small scale installations whereas the established PUREX process is used commercially for about a third of all spent nuclear fuel (the rest being largely subject to a "once through |
1697_10 | fuel cycle"). All nitrogen-fluoride compounds are volatile or gaseous at room temperature and could be fractionally distilled from the other gaseous products (including recovered uranium hexafluoride) to recover the initially used nitrogen. If the fuel could be processed in such a way as to ensure low contamination with non-radioactive carbon (not a common fission product and absent in nuclear reactors that don't use it as a moderator) then Fluoride volatility could be used to separate the produced by producing carbon tetrafluoride. is proposed for use in particularly long lived low power nuclear batteries called diamond battery. |
1697_11 | Uranium carbide
Much of what is known about uranium carbide is in the form of pin-type fuel elements for liquid metal fast reactors during their intense study during the 1960s and 1970s. However, recently there has been a revived interest in uranium carbide in the form of plate fuel and most notably, micro fuel particles (such as TRISO particles). |
1697_12 | The high thermal conductivity and high melting point makes uranium carbide an attractive fuel. In addition, because of the absence of oxygen in this fuel (during the course of irradiation, excess gas pressure can build from the formation of O2 or other gases) as well as the ability to complement a ceramic coating (a ceramic-ceramic interface has structural and chemical advantages), uranium carbide could be the ideal fuel candidate for certain Generation IV reactors such as the gas-cooled fast reactor. While the neutron cross section of carbon is low, during years of burnup, the predominantly will undergo neutron capture to produce stable as well as radioactive . Unlike the produced by using Uranium nitrate, the will make up only a small isotopic impurity in the overall carbon content and thus make the entirety of the carbon content unsuitable for non-nuclear uses but the concentration will be too low for use in nuclear batteries without enrichment. Nuclear graphite discharged |
1697_13 | from reactors where it was used as a moderator presents the same issue. |
1697_14 | Liquid fuels
Liquid fuels are liquids containing dissolved nuclear fuel and have been shown to offer numerous operational advantages compared to traditional solid fuel approaches.
Liquid-fuel reactors offer significant safety advantages due to their inherently stable "self-adjusting" reactor dynamics. This provides two major benefits:
- virtually eliminating the possibility of a run-away reactor meltdown,
- providing an automatic load-following capability which is well suited to electricity generation and high-temperature industrial heat applications.
Another major advantage of the liquid core is its ability to be drained rapidly into a passively safe dump-tank. This advantage was conclusively demonstrated repeatedly as part of a weekly shutdown procedure during the highly successful 4 year Molten Salt Reactor Experiment. |
1697_15 | Another huge advantage of the liquid core is its ability to release xenon gas which normally acts as a neutron absorber ( is the strongest known neutron poison and is produced both directly and as a decay product of as a fission product) and causes structural occlusions in solid fuel elements (leading to the early replacement of solid fuel rods with over 98% of the nuclear fuel unburned, including many long-lived actinides). In contrast, Molten Salt Reactors (MSR) are capable of retaining the fuel mixture for significantly extended periods, which not only increases fuel efficiency dramatically but also incinerates the vast majority of its own waste as part of the normal operational characteristics. A downside to letting the escape instead of allowing it to capture neutrons converting it to the basically stable and chemically inert , is that it will quickly decay to the highly chemically reactive long lived radioactive , which behaves similar to other alkali metals and can be taken |
1697_16 | up by organisms in their metabolism. |
1697_17 | Molten salts
Molten salt fuels have nuclear fuel dissolved directly in the molten salt coolant. Molten salt-fueled reactors, such as the liquid fluoride thorium reactor (LFTR), are different from molten salt-cooled reactors that do not dissolve nuclear fuel in the coolant.
Molten salt fuels were used in the LFTR known as the Molten Salt Reactor Experiment, as well as other liquid core reactor experiments. The liquid fuel for the molten salt reactor was a mixture of lithium, beryllium, thorium and uranium fluorides: LiF-BeF2-ThF4-UF4 (72-16-12-0.4 mol%). It had a peak operating temperature of 705 °C in the experiment, but could have operated at much higher temperatures since the boiling point of the molten salt was in excess of 1400 °C. |
1697_18 | Aqueous solutions of uranyl salts
The aqueous homogeneous reactors (AHRs) use a solution of uranyl sulfate or other uranium salt in water. Historically, AHRs have all been small research reactors, not large power reactors. An AHR known as the Medical Isotope Production System is being considered for production of medical isotopes.
Liquid metals or alloys
The Dual fluid reactor has a variant DFR/m which works with eutectic liquid metal alloys, e.g. U-Cr or U-Fe.
Common physical forms of nuclear fuel |
1697_19 | Uranium dioxide (UO2) powder is compacted to cylindrical pellets and sintered at high temperatures to produce ceramic nuclear fuel pellets with a high density and well defined physical properties and chemical composition. A grinding process is used to achieve a uniform cylindrical geometry with narrow tolerances. Such fuel pellets are then stacked and filled into the metallic tubes. The metal used for the tubes depends on the design of the reactor. Stainless steel was used in the past, but most reactors now use a zirconium alloy which, in addition to being highly corrosion-resistant, has low neutron absorption. The tubes containing the fuel pellets are sealed: these tubes are called fuel rods. The finished fuel rods are grouped into fuel assemblies that are used to build up the core of a power reactor. |
1697_20 | Cladding is the outer layer of the fuel rods, standing between the coolant and the nuclear fuel. It is made of a corrosion-resistant material with low absorption cross section for thermal neutrons, usually Zircaloy or steel in modern constructions, or magnesium with small amount of aluminium and other metals for the now-obsolete Magnox reactors. Cladding prevents radioactive fission fragments from escaping the fuel into the coolant and contaminating it. Besides the prevention of radioactive leaks this also serves to keep the coolant as non-corrosive as feasible and to prevent reactions between chemically aggressive fission products and the coolant. (e.g. The highly reactive alkali metal Caesium which reacts strongly with water, producing hydrogen and which is among the more common fission products) |
1697_21 | PWR fuel |
1697_22 | Pressurized water reactor (PWR) fuel consists of cylindrical rods put into bundles. A uranium oxide ceramic is formed into pellets and inserted into Zircaloy tubes that are bundled together. The Zircaloy tubes are about 1 cm in diameter, and the fuel cladding gap is filled with helium gas to improve the conduction of heat from the fuel to the cladding. There are about 179–264 fuel rods per fuel bundle and about 121 to 193 fuel bundles are loaded into a reactor core. Generally, the fuel bundles consist of fuel rods bundled 14×14 to 17×17. PWR fuel bundles are about 4 meters long. In PWR fuel bundles, control rods are inserted through the top directly into the fuel bundle. The fuel bundles usually are enriched several percent in 235U. The uranium oxide is dried before inserting into the tubes to try to eliminate moisture in the ceramic fuel that can lead to corrosion and hydrogen embrittlement. The Zircaloy tubes are pressurized with helium to try to minimize pellet-cladding interaction |
1697_23 | which can lead to fuel rod failure over long periods. |
1697_24 | BWR fuel
In boiling water reactors (BWR), the fuel is similar to PWR fuel except that the bundles are "canned". That is, there is a thin tube surrounding each bundle. This is primarily done to prevent local density variations from affecting neutronics and thermal hydraulics of the reactor core. In modern BWR fuel bundles, there are either 91, 92, or 96 fuel rods per assembly depending on the manufacturer. A range between 368 assemblies for the smallest and 800 assemblies for the largest U.S. BWR forms the reactor core. Each BWR fuel rod is backfilled with helium to a pressure of about three atmospheres (300 kPa). |
1697_25 | CANDU fuel |
1697_26 | CANDU fuel bundles are about a half meter long and 10 cm in diameter. They consist of sintered (UO2) pellets in zirconium alloy tubes, welded to zirconium alloy end plates. Each bundle is roughly 20 kg, and a typical core loading is on the order of 4500–6500 bundles, depending on the design. Modern types typically have 37 identical fuel pins radially arranged about the long axis of the bundle, but in the past several different configurations and numbers of pins have been used. The CANFLEX bundle has 43 fuel elements, with two element sizes. It is also about 10 cm (4 inches) in diameter, 0.5 m (20 in) long and weighs about 20 kg (44 lb) and replaces the 37-pin standard bundle. It has been designed specifically to increase fuel performance by utilizing two different pin diameters. Current CANDU designs do not need enriched uranium to achieve criticality (due to their more efficient heavy water moderator), however, some newer concepts call for low enrichment to help reduce the size of |
1697_27 | the reactors. |
1697_28 | Less-common fuel forms
Various other nuclear fuel forms find use in specific applications, but lack the widespread use of those found in BWRs, PWRs, and CANDU power plants. Many of these fuel forms are only found in research reactors, or have military applications.
Magnox fuel
Magnox (magnesium non-oxidising) reactors are pressurised, carbon dioxide–cooled, graphite-moderated reactors using natural uranium (i.e. unenriched) as fuel and Magnox alloy as fuel cladding. Working pressure varies from 6.9 to 19.35 bar for the steel pressure vessels, and the two reinforced concrete designs operated at 24.8 and 27 bar. Magnox alloy consists mainly of magnesium with small amounts of aluminium and other metals—used in cladding unenriched uranium metal fuel with a non-oxidising covering to contain fission products. This material has the advantage of a low neutron capture cross-section, but has two major disadvantages: |
1697_29 | It limits the maximum temperature, and hence the thermal efficiency, of the plant.
It reacts with water, preventing long-term storage of spent fuel under water.
Magnox fuel incorporated cooling fins to provide maximum heat transfer despite low operating temperatures, making it expensive to produce. While the use of uranium metal rather than oxide made reprocessing more straightforward and therefore cheaper, the need to reprocess fuel a short time after removal from the reactor meant that the fission product hazard was severe. Expensive remote handling facilities were required to address this danger
TRISO fuel |
1697_30 | Tristructural-isotropic (TRISO) fuel is a type of micro fuel particle. It consists of a fuel kernel composed of UOX (sometimes UC or UCO) in the center, coated with four layers of three isotropic materials deposited through fluidized chemical vapor deposition (FCVD). The four layers are a porous buffer layer made of carbon that absorbs fission product recoils, followed by a dense inner layer of protective pyrolytic carbon (PyC), followed by a ceramic layer of SiC to retain fission products at elevated temperatures and to give the TRISO particle more structural integrity, followed by a dense outer layer of PyC. TRISO particles are then encapsulated into cylindrical or spherical graphite pellets. TRISO fuel particles are designed not to crack due to the stresses from processes (such as differential thermal expansion or fission gas pressure) at temperatures up to 1600 °C, and therefore can contain the fuel in the worst of accident scenarios in a properly designed reactor. Two such |
1697_31 | reactor designs are the prismatic-block gas-cooled reactor (such as the GT-MHR) and the pebble-bed reactor (PBR). Both of these reactor designs are high temperature gas reactors (HTGRs). These are also the basic reactor designs of very-high-temperature reactors (VHTRs), one of the six classes of reactor designs in the Generation IV initiative that is attempting to reach even higher HTGR outlet temperatures. |
1697_32 | TRISO fuel particles were originally developed in the United Kingdom as part of the Dragon reactor project. The inclusion of the SiC as diffusion barrier was first suggested by D. T. Livey. The first nuclear reactor to use TRISO fuels was the Dragon reactor and the first powerplant was the THTR-300. Currently, TRISO fuel compacts are being used in the experimental reactors, the HTR-10 in China, and the High-temperature engineering test reactor in Japan. Spherical fuel elements utilizing a TRISO particle with a UO2 and UC solid solution kernel are being used in the Xe-100 in the United States.
QUADRISO fuel |
1697_33 | In QUADRISO particles a burnable neutron poison (europium oxide or erbium oxide or carbide) layer surrounds the fuel kernel of ordinary TRISO particles to better manage the excess of reactivity. If the core is equipped both with TRISO and QUADRISO fuels, at beginning of life neutrons do not reach the fuel of the QUADRISO particles because they are stopped by the burnable poison. During reactor operation, neutron irradiation of the poison causes it to "burn up" or progressively transmute to non-poison isotopes, depleting this poison effect and leaving progressively more neutrons available for sustaining the chain-reaction. This mechanism compensates for the accumulation of undesirable neutron poisons which are an unavoidable part of the fission products, as well as normal fissile fuel "burn up" or depletion. In the generalized QUADRISO fuel concept the poison can eventually be mixed with the fuel kernel or the outer pyrocarbon. The QUADRISO concept has been conceived at Argonne |
1697_34 | National Laboratory. |
1697_35 | RBMK fuel
RBMK reactor fuel was used in Soviet-designed and built RBMK-type reactors. This is a low-enriched uranium oxide fuel. The fuel elements in an RBMK are 3 m long each, and two of these sit back-to-back on each fuel channel, pressure tube. Reprocessed uranium from Russian VVER reactor spent fuel is used to fabricate RBMK fuel. Following the Chernobyl accident, the enrichment of fuel was changed from 2.0% to 2.4%, to compensate for control rod modifications and the introduction of additional absorbers.
CerMet fuel
CerMet fuel consists of ceramic fuel particles (usually uranium oxide) embedded in a metal matrix. It is hypothesized that this type of fuel is what is used in United States Navy reactors. This fuel has high heat transport characteristics and can withstand a large amount of expansion.
Plate-type fuel |
1697_36 | Plate-type fuel has fallen out of favor over the years. Plate-type fuel is commonly composed of enriched uranium sandwiched between metal cladding. Plate-type fuel is used in several research reactors where a high neutron flux is desired, for uses such as material irradiation studies or isotope production, without the high temperatures seen in ceramic, cylindrical fuel. It is currently used in the Advanced Test Reactor (ATR) at Idaho National Laboratory, and the nuclear research reactor at the University of Massachusetts Lowell Radiation Laboratory.
Sodium-bonded fuel
Sodium-bonded fuel consists of fuel that has liquid sodium in the gap between the fuel slug (or pellet) and the cladding. This fuel type is often used for sodium-cooled liquid metal fast reactors. It has been used in EBR-I, EBR-II, and the FFTF. The fuel slug may be metallic or ceramic. The sodium bonding is used to reduce the temperature of the fuel. |
1697_37 | Accident tolerant fuels
Accident tolerant fuels (ATF) are a series of new nuclear fuel concepts, researched in order to improve fuel performance under accident conditions, such as loss-of-coolant accident (LOCA) or reaction-initiated accidents (RIA). These concerns became more prominent after the Fukushima Daiichi nuclear disaster in Japan, in particular regarding light-water reactor (LWR) fuels performance under accident conditions.
The aim of the research is to develop nuclear fuels that can tolerate loss of active cooling for a considerably longer period than the existing fuel designs and prevent or delay the release of radionuclides during an accident. This research is focused on reconsidering the design of fuel pellets and cladding, as well as the interactions between the two.
Spent nuclear fuel |
1697_38 | Used nuclear fuel is a complex mixture of the fission products, uranium, plutonium, and the transplutonium metals. In fuel which has been used at high temperature in power reactors it is common for the fuel to be heterogeneous; often the fuel will contain nanoparticles of platinum group metals such as palladium. Also the fuel may well have cracked, swollen, and been heated close to its melting point. Despite the fact that the used fuel can be cracked, it is very insoluble in water, and is able to retain the vast majority of the actinides and fission products within the uranium dioxide crystal lattice. The radiation hazard from spent nuclear declines as its radioactive components decay, but remains high for many years. For example 10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly still exceeds 10,000 rem/hour, resulting in a fatal dose in just minutes.
Oxide fuel under accident conditions |
1697_39 | Two main modes of release exist, the fission products can be vaporised or small particles of the fuel can be dispersed.
Fuel behavior and post-irradiation examination
Post-Irradiation Examination (PIE) is the study of used nuclear materials such as nuclear fuel. It has several purposes. It is known that by examination of used fuel that the failure modes which occur during normal use (and the manner in which the fuel will behave during an accident) can be studied. In addition information is gained which enables the users of fuel to assure themselves of its quality and it also assists in the development of new fuels. After major accidents the core (or what is left of it) is normally subject to PIE to find out what happened. One site where PIE is done is the ITU which is the EU centre for the study of highly radioactive materials. |
1697_40 | Materials in a high-radiation environment (such as a reactor) can undergo unique behaviors such as swelling and non-thermal creep. If there are nuclear reactions within the material (such as what happens in the fuel), the stoichiometry will also change slowly over time. These behaviors can lead to new material properties, cracking, and fission gas release.
The thermal conductivity of uranium dioxide is low; it is affected by porosity and burn-up. The burn-up results in fission products being dissolved in the lattice (such as lanthanides), the precipitation of fission products such as palladium, the formation of fission gas bubbles due to fission products such as xenon and krypton and radiation damage of the lattice. The low thermal conductivity can lead to overheating of the center part of the pellets during use. The porosity results in a decrease in both the thermal conductivity of the fuel and the swelling which occurs during use. |
1697_41 | According to the International Nuclear Safety Center the thermal conductivity of uranium dioxide can be predicted under different conditions by a series of equations.
The bulk density of the fuel can be related to the thermal conductivity
Where ρ is the bulk density of the fuel and ρtd is the theoretical density of the uranium dioxide.
Then the thermal conductivity of the porous phase (Kf) is related to the conductivity of the perfect phase (Ko, no porosity) by the following equation. Note that s is a term for the shape factor of the holes.
Kf = Ko(1 − p/1 + (s − 1)p) |
1697_42 | Rather than measuring the thermal conductivity using the traditional methods such as Lees' disk, the Forbes' method, or Searle's bar, it is common to use Laser Flash Analysis where a small disc of fuel is placed in a furnace. After being heated to the required temperature one side of the disc is illuminated with a laser pulse, the time required for the heat wave to flow through the disc, the density of the disc, and the thickness of the disk can then be used to calculate and determine the thermal conductivity.
λ = ρCpα
λ thermal conductivity
ρ density
Cp heat capacity
α thermal diffusivity
If t1/2 is defined as the time required for the non illuminated surface to experience half its final temperature rise then.
α = 0.1388 L2/t1/2
L is the thickness of the disc
For details see K. Shinzato and T. Baba (2001).
Radioisotope decay fuels
Radioisotope battery |
1697_43 | An atomic battery (also called a nuclear battery or radioisotope battery) is a device which uses the radioactive decay to generate electricity. These systems use radioisotopes that produce low energy beta particles or sometimes alpha particles of varying energies. Low energy beta particles are needed to prevent the production of high energy penetrating bremsstrahlung radiation that would require heavy shielding. Radioisotopes such as plutonium-238, curium-242, curium-244 and strontium-90 have been used. Tritium, nickel-63, promethium-147, and technetium-99 have been tested. |
1697_44 | There are two main categories of atomic batteries: thermal and non-thermal. The non-thermal atomic batteries, which have many different designs, exploit charged alpha and beta particles. These designs include the direct charging generators, betavoltaics, the optoelectric nuclear battery, and the radioisotope piezoelectric generator. The thermal atomic batteries on the other hand, convert the heat from the radioactive decay to electricity. These designs include thermionic converter, thermophotovoltaic cells, alkali-metal thermal to electric converter, and the most common design, the radioisotope thermoelectric generator.
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator (RTG) is a simple electrical generator which converts heat into electricity from a radioisotope using an array of thermocouples. |
1697_45 | has become the most widely used fuel for RTGs, in the form of plutonium dioxide. It has a half-life of 87.7 years, reasonable energy density, and exceptionally low gamma and neutron radiation levels. Some Russian terrestrial RTGs have used ; this isotope has a shorter half-life and a much lower energy density, but is cheaper. Early RTGs, first built in 1958 by the U.S. Atomic Energy Commission, have used . This fuel provides phenomenally huge energy density, (a single gram of polonium-210 generates 140 watts thermal) but has limited use because of its very short half-life and gamma production, and has been phased out of use for this application.
Radioisotope heater unit (RHU)
A radioisotope heater unit (RHU) typically provides about 1 watt of heat each, derived from the decay of a few grams of plutonium-238. This heat is given off continuously for several decades. |
1697_46 | Their function is to provide highly localised heating of sensitive equipment (such as electronics in outer space). The Cassini–Huygens orbiter to Saturn contains 82 of these units (in addition to its 3 main RTGs for power generation). The Huygens probe to Titan contains 35 devices.
Fusion fuels |
1697_47 | Fusion fuels are fuels to use in hypothetical Fusion power reactors. They include deuterium (2H) and tritium (3H) as well as helium-3 (3He). Many other elements can be fused together, but the larger electrical charge of their nuclei means that much higher temperatures are required. Only the fusion of the lightest elements is seriously considered as a future energy source. Fusion of the lightest atom, 1H hydrogen, as is done in the Sun and stars, has also not been considered practical on Earth. Although the energy density of fusion fuel is even higher than fission fuel, and fusion reactions sustained for a few minutes have been achieved, utilizing fusion fuel as a net energy source remains only a theoretical possibility. |
1697_48 | First-generation fusion fuel
Deuterium and tritium are both considered first-generation fusion fuels; they are the easiest to fuse, because the electrical charge on their nuclei is the lowest of all elements. The three most commonly cited nuclear reactions that could be used to generate energy are:
2H + 3H → n (14.07 MeV) + 4He (3.52 MeV)
2H + 2H → n (2.45 MeV) + 3He (0.82 MeV)
2H + 2H → p (3.02 MeV) + 3H (1.01 MeV) |
1697_49 | Second-generation fusion fuel
Second-generation fuels require either higher confinement temperatures or longer confinement time than those required of first-generation fusion fuels, but generate fewer neutrons. Neutrons are an unwanted byproduct of fusion reactions in an energy generation context, because they are absorbed by the walls of a fusion chamber, making them radioactive. They cannot be confined by magnetic fields, because they are not electrically charged. This group consists of deuterium and helium-3. The products are all charged particles, but there may be significant side reactions leading to the production of neutrons.
2H + 3He → p (14.68 MeV) + 4He (3.67 MeV)
Third-generation fusion fuel |
1697_50 | Third-generation fusion fuels produce only charged particles in the primary reactions, and side reactions are relatively unimportant. Since a very small amount of neutrons is produced, there would be little induced radioactivity in the walls of the fusion chamber. This is often seen as the end goal of fusion research. 3He has the highest Maxwellian reactivity of any 3rd generation fusion fuel. However, there are no significant natural sources of this substance on Earth.
3He + 3He → 2 p + 4He (12.86 MeV)
Another potential aneutronic fusion reaction is the proton-boron reaction:
p + 11B → 3 4He (8.7 MeV) |
1697_51 | Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons. With 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T.
See also
Fissile material
Global Nuclear Energy Partnership
Integrated Nuclear Fuel Cycle Information System
Lists of nuclear disasters and radioactive incidents
Nuclear fuel bank
Nuclear fuel cycle
Reprocessed uranium
Uranium market
References
External links
PWR fuel
Picture showing handling of a PWR bundle
BWR fuel
Physical description of LWR fuel
Links to BWR photos from the nuclear tourist webpage
CANDU fuel
CANDU Fuel pictures and FAQ
Basics on CANDU design
The Evolution of CANDU Fuel Cycles and their Potential Contribution to World Peace |
1697_52 | CANDU Fuel and Reactor Specifics (Nuclear Tourist)
Candu Fuel Rods and Bundles
TRISO fuel
TRISO fuel descripción
Non-Destructive Examination of SiC Nuclear Fuel Shell using X-Ray Fluorescence Microtomography Technique
GT-MHR fuel compact process
Description of TRISO fuel for "pebbles"
LANL webpage showing various stages of TRISO fuel production
Method to calculate the temperature profile in TRISO fuel
QUADRISO fuel
Conceptual Design of QUADRISO Fuel
CERMET fuel
Thoria-based Cermet Nuclear Fuel: Sintered Microsphere Fabrication by Spray Drying
Plate type fuel
List of reactors at INL and picture of ATR core
ATR plate fuel
TRIGA fuel
Fusion fuel
Advanced fusion fuels presentation
Nuclear reprocessing
Nuclear technology
Nuclear chemistry
Actinides |
1698_0 | The political views of Adolf Hitler have presented historians and biographers with some difficulty. His writings and methods were often adapted to need and circumstance, although there were some steady themes, including antisemitism, anti-communism, anti-parliamentarianism, German Lebensraum ("living space"), belief in the superiority of an "Aryan race" and an extreme form of German nationalism. Hitler personally claimed he was fighting against "Jewish Marxism". |
1698_1 | Adolf Hitler's political views were formed during three periods, namely (1) his years as a poverty-stricken young man in Vienna and Munich prior to World War I, during which he turned to nationalist-oriented political pamphlets and antisemitic newspapers out of distrust for mainstream newspapers and political parties; (2) the closing months of World War I when Germany lost the war, as Hitler is said to have developed his extreme nationalism during this time, desiring to "save" Germany from both external and internal "enemies" who in his view betrayed it; (3) and the 1920s, during which his early political career began and he wrote Mein Kampf. Hitler formally renounced his Austrian citizenship on 7 April 1925, but did not acquire German citizenship until almost seven years later in 1932; thereby allowing him to run for public office. Hitler was influenced by Benito Mussolini, who was appointed Prime Minister of Italy in October 1922 after his "March on Rome". In many ways, Hitler |
1698_2 | epitomizes "the force of personality in political life" as mentioned by Friedrich Meinecke. He was essential to the very framework of Nazism's political appeal and its manifestation in Germany. So important were Hitler's views that they immediately affected the political policies of Nazi Germany. He asserted the Führerprinzip ("leader principle"). The principle relied on absolute obedience of all subordinates to their superiors. Hitler viewed the party structure and later the government structure as a pyramid, with himself—the infallible leader—at the apex. |
1698_3 | Hitler firmly believed that the force of "will" was decisive in determining the political course for a nation and rationalized his actions accordingly. Given that Hitler was appointed "leader of the German Reich for life", he "embodied the supreme power of the state and, as the delegate of the German people", it was his role to determine the "outward form and structure of the Reich". To that end, Hitler's political motivation consisted of an ideology that combined traditional German and Austrian antisemitism with an intellectualized racial doctrine resting on an admixture of bits and pieces of social Darwinism and the ideas – mostly obtained second-hand and only partially understood – of Friedrich Nietzsche, Arthur Schopenhauer, Richard Wagner, Houston Stewart Chamberlain, Arthur de Gobineau and Alfred Rosenberg as well as Paul de Lagarde, Georges Sorel, Alfred Ploetz and others.
Army intelligence agent |
1698_4 | During World War I, Hitler was temporarily blinded in a mustard gas attack on 15 October 1918 for which he was hospitalised in Pasewalk. While there, Hitler learned of Germany's defeat, with the Armistice to take effect on 11 November. By his own account—upon receiving this news, he suffered a second bout of blindness. Days after digesting this traumatic news, Hitler later stated his decision: "... my own fate became known to me ... I ... decided to go into politics." On 19 November 1918, Hitler was discharged from the Pasewalk hospital and returned to Munich, which at the time was in a state of socialist upheaval. Arriving on 21 November, he was assigned to 7th Company of the 1st Replacement Battalion of the 2nd Infantry Regiment. In December he was reassigned to a Prisoner of War camp in Traunstein as a guard. There he would stay until the camp dissolved January 1919. |
1698_5 | Returning to Munich, Hitler spent a few months in barracks waiting for reassignment. During this time Munich was a part of the People's State of Bavaria, which was still in a state of chaos with a number of assassinations occurring including that of socialist Kurt Eisner who was shot dead in Munich by a German nationalist on 21 February 1919. Other acts of violence were the killings of both Major Paul Ritter von Jahreiß and the conservative MP Heinrich Osel. In this political turmoil, Berlin sent in the military, whom the communists called the "White Guards of Capitalism". On 3 April 1919, Hitler was elected as the liaison of his military battalion and again on 15 April. During this time he urged his unit to stay out of the fighting and not join either side. The Bavarian Soviet Republic was officially crushed on 6 May 1919, when Lt. General Burghard von Oven and his military forces declared the city secure. In the aftermath of arrests and executions, Hitler denounced a fellow liaison, |
1698_6 | Georg Dufter, as a Soviet "radical rabble-rouser." Other testimony he gave to the military board of inquiry allowed them to root out other members of the military that "had been infected with revolutionary fervor." For his anti-communist views he was allowed to avoid discharge when his unit was disbanded in May 1919. |
1698_7 | In June 1919 he was moved to the demobilization office of the 2nd Infantry Regiment. Around this time the German military command released an edict that the army's main priority was to "carry out, in conjunction with the police, stricter surveillance of the population ... so that the ignition of any new unrest can be discovered and extinguished." In May 1919 Karl Mayr became commander of the 6th Battalion of the guards regiment in Munich and from 30 May the head of the "Education and Propaganda Department" (Dept Ib/P) of the Bavarian Reichswehr, Headquarters 4. In this capacity as head of the intelligence department, Mayr recruited Hitler as an undercover agent in early June 1919. Under Captain Mayr "national thinking" courses were arranged at the Reichswehrlager Lechfeld near Augsburg, with Hitler attending from 10 to 19 July 1919. During this time Hitler so impressed Mayr that he assigned him to an anti-bolshevik "educational commando" as 1 of 26 instructors in the summer of 1919. |
1698_8 | These courses he taught helped popularize the notion that there was a scapegoat responsible for the outbreak of war and Germany's defeat. Hitler's own bitterness over the collapse of the war effort also began to shape his ideology. Like other German nationalists, he believed the Dolchstoßlegende (stab-in-the-back myth) which claimed that the German Army, "undefeated in the field", had been "stabbed in the back" on the home front by civilian leaders and Marxists, later dubbed the "November criminals". "International Jewry" was described as a scourge composed of communists relentlessly destroying Germany. Such scapegoating was essential to Hitler's political career and it seems that he genuinely believed that Jews were responsible for Germany's post-war troubles. |
1698_9 | In July 1919, Hitler was appointed Verbindungsmann (intelligence agent) of an Aufklärungskommando (reconnaissance commando) of the Reichswehr, both to influence other soldiers and to infiltrate the German Workers' Party (DAP). Much like the political activists in the DAP, Hitler blamed the loss of the war on Jewish intrigue at home and abroad, espousing völkisch-nationalist political beliefs with the intention of resurrecting Germany's greatness by smashing the Versailles Treaty. Along those lines, Hitler proclaimed that the "German yoke must be broken by German iron" (Das deutsche Elend muß durch deutsches Eisen zerbrochen werden).
German Workers' Party |
1698_10 | In September 1919 Hitler wrote what is often deemed his first antisemitic text, requested by Mayr as a reply to an inquiry by Adolf Gemlich, who had participated in the same "educational courses" as Hitler. In this report, Hitler argued for a "rational anti-Semitism" which would not resort to pogroms, but instead "legally fight and remove the privileges enjoyed by the Jews as opposed to other foreigners living among us. Its final goal, however, must be the irrevocable removal of the Jews themselves". Most people at the time understood this as a call for forced expulsion. Europe has a long history of expelling Jews and the auto-da-fé of the Inquisition. |
1698_11 | While he studied the activities of the German Workers' Party (DAP), Hitler became impressed with founder Anton Drexler's antisemitic, nationalist, anti-capitalist and anti-Marxist ideas. Drexler was impressed with Hitler's oratory skills, and invited him to join the DAP on 12 September 1919. On the orders of his army superiors, Hitler applied to join the party and within a week was accepted as party member 555 (the party began counting membership at 500 to give the impression they were a much larger party). In Mein Kampf, Hitler later claimed to be the seventh party member, one of many myths in Mein Kampf designed, as biographer Ian Kershaw writes, "to serve the Führer legend". |
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