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Burnup, Depletion, and Temperature Feedback
Published in Robert E. Masterson, Introduction to Nuclear Reactor Physics, 2017
The TRIGA reactor was originally developed by the General Atomics Company, whose corporate headquarters are located in San Diego, California. The word TRIGA is an acronym for Training, Research, Isotopes, and General Atomics. There are approximately 40 TRIGA reactors in operation around the world today, and the number appears to be growing at the rate of one or two a year. (See Figures 17.22 and 17.23 to see their current locations). TRIGA reactors can be designed in many different sizes and configurations, and their stated power levels range from 20 kW to about 16 MW. Because of their inherent thermal stability, TRIGA reactors also happen to be very popular research and training tools. The concept of the TRIGA reactor was originally proposed by Dr. Edward Teller (the father of the H Bomb—see Figure 17.24) and some of his colleagues in 1956. However, Freeman Dyson, whose picture is shown in Figure 17.25, was probably the greatest single contributor to its design. Freeman Dyson was also one of the first physicists to actively promote the use of Feynman diagrams, which are now commonly used by nuclear scientists and engineers today.
The Other Energy Markets
Published in Anco S. Blazev, Global Energy Market Trends, 2021
Some of the metal nuclear materials are: Uranium dioxide (UO2) nuclear fuel is a black solid material, which is prepared by reacting uranyl nitrate with ammonia to form a solid (ammonium uranate). It is then heated (calcined) to form U3O8 that can then be converted by heating in an argon/hydrogen mixture at 700°C to form UO2. Thus obtained UO2 is mixed with an organic binder and pressed into pellets, which are then fired at a high temperature again in argon/hydrogen gas mixture to sinter the pellets into a solid material with few pores.Mixed oxide, or MOX, is a blend of plutonium and natural or depleted uranium which behaves similarly 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 (LWR) which are used in the global nuclear power generation.TRIGA nuclear fuel is used in TRIGA (training, research, isotopes, general atomics) reactors, which use uranium-zirconium-hydride (UZrH) fuel, which has a built-in safety, where as the temperature of the core increases, the fuel reactivity decreases. This pretty much eliminates the possibility of a meltdown. Most cores that use this fuel are “high leakage” cores where the excess leaked neutrons can be utilized for research.
Nuclear and Hydro Power
Published in Anco S. Blazev, Energy Security for The 21st Century, 2021
Some of the metal nuclear materials are: Uranium dioxide (UO2) nuclear fuel is a black solid material, which is prepared by reacting uranyl nitrate with ammonia to form a solid (ammonium uranate). It is then heated (calcined) to form U3O8 that can then be converted by heating in an argon/hydrogen mixture at 700°C to form UO2. Thus obtained UO2 is mixed with an organic binder and pressed into pellets, which are then fired at a high temperature again in argon/hydrogen gas mixture to sinter the pellets into a solid material with few pores.Mixed oxide, or MOX, is a blend of plutonium and natural or depleted uranium which behaves similarly 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 (LWR) which are used in the global nuclear power generation.TRIGA nuclear fuel is used in TRIGA (training, research, isotopes, general atomics) reactors, which use uranium-zirconium-hydride (UZrH) fuel, which has a built-in safety, where as the temperature of the core increases, the fuel reactivity decreases. This pretty much eliminates the possibility of a meltdown. Most cores that use this fuel are “high leakage” cores where the excess leaked neutrons can be utilized for research.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 USA. A further 35 reactors have been installed in other countries.Actinide nuclear fuel is a by-product of fast neutron reactors, where 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 the minor actinides. It can be made inherently safe as thermal expansion of the metal alloy will increase neutron leakage.
Reactor Physics Considerations for Use of Yttrium Hydride Moderator
Published in Nuclear Science and Engineering, 2022
Brian J. Ade, Benjamin R. Betzler, Joseph R. Burns, Christopher W. Chapman, Jianwei Hu
Use of ZrHx as a neutron moderator in reactors is well established—it is the primary neutron moderator in Training, Research, Isotopes, General Atomics (TRIGA®) reactors.1,2 TRIGA reactors use an alloy of uranium and zirconium hydride (UZrH) as fuel. Because the neutron moderator is mixed with the fuel, the reactor provides extreme negative reactivity feedback in response to increases in temperature, making the reactor inherently safe. As a result, TRIGA reactors are commonly used for training and testing at universities and other research institutions around the world. The UZrH fuel has also been used in a number of other reactors, including the Systems Nuclear Auxiliary Power Program3 (SNAP) series of space reactors. However, use of solid ZrHx not alloyed with uranium has been less common.
Assessment of Factory Fabrication Considerations for Nuclear Microreactors
Published in Nuclear Technology, 2023
Abdalla Abou-Jaoude, Yasir Arafat, Chandrakanth Bolisetti, Botros Hanna, Joshua Belvedere, James Blocker, Brandon Cooper, Shanda Harmon, Dan McCarthy
MARVEL is a 100-kW(thermal) NaK (sodium-potassium eutectic)–cooled reactor coupled to four Stirling engines for power conversion. The reactor utilizes uranium zirconium hydride, also called Training, research, isotopes, General Atomic (TRIGA) fuel. Both beryllium metal and oxide forms are used as reflector material to minimize the initial fuel loading. Four safety-related control, drums and a defense-in-depth central control rod are used for reactivity control and emergency shutdown. Four intermediate, open-pool, lead heat exchangers separate the power conversion units from the NaK coolant. An illustration of the reactor is provided in Fig. 6.