Plutonium Ceramic Fuels

These presentations are reprinted in this volume as a formal ARW Proceedings in the NATO Science Series. The representative technical papers contained here cover nuclear material safety topics on the storage and disposition of excess plutonium and high enriched uranium (HEU) fissile materials, including vitrification, mixed oxide (MOX) fuel fabrication, plutonium ceramics, reprocessing, geologic disposal, transportation, and Russian regulatory processes. 

Farkas, M.S., Storhok, V.W, Pardue, W.M., Smith, R.A., Veigel, N.D., Miller,N.E., Wright, T.R., Bames, R.H., Chubb, W., Lemmon, A. W., Berry, W.E., Rough, F.A, Fuel and Fertile Materials -Uranium Metal and Alloys - Plutonium - Thorium - Metal-Ceramic Fuels - Coated-Paiticle Fuel Materials - Uranium and Thorium Oxides - Uranium Carbides, Nitrides, Phosphides, Sulfides and Arsenides - Fuel-Water Reactions , Reactor Mater., 9(3), 151-165 (1966) (Assessment, Electr. Prop., Meehan. Prop., Phys. Prop., Transport Phenomena, 77)... 

Contrary to ceramic fuel, such as UO2, the total fission product gases may be released into the plenum rather than locked in the fuel structure. Clearly some gases will be locked in pockets in the fuel alloy. However, the initial backfill pressure in the plenum and the total plenum size should be determined based on a 100% plutonium bumup. The time-dependent fission product gas source term can be determined from appropriate isotopic generation and depletion calculations. The pressure and clad requirements can be calculated from the corresponding fuel performance models. 

Components in the process of design and fabrication of ceramic plutonium fuels at Hanford Engineering Development Laboratory (HEDL) are displayed in Figure 5. The plan for the fuel fabrication demonstration facility at HEDL is shown in Figure 6. 

This reaction occurs in reactors designed specifically to produce fissionable fuel. These reactors are frequently called breeder reactors because they produce more fissionable fuel than is used in the reaction. Plutonium is also produced in thermal reactors that contain Plutonium can be obtained through the processing of spent fuel elements. To be useful as a fuel, plutonium must be alloyed to be in a stable phase as a metal or a ceramic. 

The redundant weapons plutonium, according to the policy of the Minatom of Russia, cannot be buried as waste and should be used as nuclear fuel. Now creation of ceramic plutonium fuel is considered as an alternative to MOX fuel. The given... 

The objective of this paper is to discuss the safety issues associated with the immobilization of excess weapons plutonium in ceramic form in the United States. The U.S. government has recommended a dual-track approach to dispose of excess weapons plutonium. According to this approach, about 33 metric tons of pure Pu will be fabricated into mixed oxide (MOX) fuels which will be burned in commercial nuclear light water reactors and up to 17 metric tons of impure Pu will be immobilized into ceramic form which will be permanently disposed of in a geologic repository. It should be noted that a portion of the 33 metric tons of pure Pu may also be immobilized into ceramic form depending on the future decision of the U.S. government. 

Milling. Both processes involve milling. The milling requirement of PUO2 particulates for the ceramic process is less than 20 pm, which is comparable to the 10 pm nominal requirement for the MOX fuel process. For plutonium oxide, particulate less than about 3 pm (corresponding to an aerodynamic equivalent diameter of 10 pm) are respirable. Thus under similar conditions, the potential inhalation dose associated with a spill accident of plutonium oxide powder for the ceramic process is no worse than that for the MOX fuel process. 

Switzerland Within the framework of the CAPRA project, the fuel option for amplified plutonium consumption is being studied. In the area of materials for actinide transmutation, the following tasks has been completed in 1994 (1) preparatory experiments and solubility tests for (Ui, PUJ O2 (0.25 < x < 0.65 and for (Uj., PU,J N (0.25 < x< 0.75), as possible materials for the efficient fission of plutonium in a fast neutron flux (2) fabrication of pure PuN-microspheres for ceramic-metal fuel (3) design calculations for sphere-pac segments, based on the idea of a ceramic-metal fiiel (4) material preparation of (U, Zr) N and pelletization tests of TiN and (U, Zr)N for the irradiation experiment in the reactor PHENIX (5) experimental preparations of (Ce,U) O2, (Ce,U,Pu)02 and (Ce, PU)02 for the CAPRA core with lower Pu content, and (6) cleaning of americium from waste streams of the plutonium separation equipment (extraction chromatography). 

The layout of a CerMet (ceramic-metal) fuel based on ceramic particles as an advanced solution for plutonium incineration without uranium is addressed with model calculations for thermal and mechanical behaviour. 

The storage and use of the three metric tons of plutonium fuel used in the Zero Power Plutonium Reactor (ZPPR) has posed unique problems in the history of zero-power, fast-critical-facility operation. Similar problems may be encountered in the future, however, with the several tons of metallic or ceramic elements that will fuel individual, large, fast power reactors. 

Structural materials are used as fuel cladding and assembly wrappers, and also as fuel stabilisers. In connection with fast reactors designed as plutonium burners there is an interest in fuels which are a dispersion of plutonium oxide particles in a ceramic, such as MgO or MgAh04 (a CERCER fuel) or in a metallic matrix such as Cr, or Cr-W alloy (a CERMET... 

After working with beryllium I moved on to study nuclear reactor fabrication. In this study I worked on determining the surface area, size and shape distributions of uranium dioxide and plutonium dioxide powders used to fabricate fuel rods. Looking back I see that my initiation into powder technology was a baptism of fire since all of these powders were extremely toxic and dangerous. The technology that I studied in those years is currently very applicable to the study of modern ceramic materials and powder metallurgical routes to finished products [1,2]. 

Two fuel forms have the potential to satisfy the GFR requirements (1) a ceramic plate-type fuel element and (2) a ceramic pin-type fuel element. The reference material for the structure is reinforced ceramic comprised of a sUicon carbide composite matrix ceramic. The fuel compound is made of pellets of mixed uranium-plutonium-minor actinide carbide. A leak-tight barrier made of a refractory metal or of Si-based multilayer ceramics is added to prevent fission products from diffusing through the clad [1]. 

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