Uranium-plutonium systems, fuel

The uraniimi fuel cycle for the uranium-plutonium system is a multicomponent system of chemical process operations that begins with mining uranium ore from the earth as... 

Initial reactor-fuel materials which have been considered [28] in uranium-plutonium systems are UO2SO4-D2O, U()2(X()3)2-D20, and UO3-D2O. Of these, the system which gives the highest conversion ratio is the one containing U0, j-D20. However, because of the relatively low values for ([ 235) r7(Pu ), it is presently considered that the attainment of a... 

Effect of Design Variables on Fuel Costs IN Uranium-Plutonium Systems... 

In an energy system based on breeder reactors, it is necessary to process the used fuel elements to recover the fertile elements and discard the waste products. The difficulty with this approach lies in the handling of the uranium, plutonium and highly radioactive nuclear fission products. 

Plutonium nitride. Unlike the corresponding uranium-nitrogen system, only the one plutonium nitride PuN exists. It is prepared by heating plutonium hydride in nitrogen at 250 to 400 C, by reacting plutonium metal with a hydrogen-ammonia mixture at 600°C, or by direction reaction of molten plutonium with nitrogen at 1000 C. Plutonium nitride forms solid solutions with UN. However, because of the appreciable volatility and dissociation of PuN at temperatures at about 1600 C and above, the ternary (U, Pu)N is less attractive as a nuclear fuel than pure UN [K2, S4]. 

The binary systems actually and potentially important as nuclear fuel include oxides, carbides, nitrides, phosphides, and sulfides of uranium, plutonium, and thorium. An increasing amount of detailed information is becoming available on the phase equilibria of these compounds, but the relations existing between the composition (especially nonstoichiometric) and the vapor pressure (or activity) of each component are known only for a limited number of systems. 

There are many examples of the studies on SLM for nuclear applications in the literature. SLMs were tested for high-level radioactive waste treatment combined with removal of actinides and other fission products from the effluents from nuclear fuel reprocessing plants. The recovery of the species, such as uranium, plutonium, thorium, americium, cerium, europium, strontium, and cesium, was investigated in vari-ons extracting-stripping systems. Selective permeation... 

In parallel with the work done in collaboration with the European partners BNFL has conducted studies of the potential role of fast reactors in the UK and elsewhere. It is important to consider the fuel cycle as a whole and to make use of fast reactors in the optimum way to maximise safety and economic advantage while minimising environmental impact and proliferation risks. To this end accelerator-based systems as alternatives to critical reactors, and the thorium cycle as an alternative to the uranium-plutonium cycle, have been examined with particular reference to the implications for fuel fabrication, reprocessing and waste disposal. This work continues but the initial conclusion is that the critical Pu-fuelled fast reactor, properly integrated with reactors of other types, and with optimised arrangements for Pu recycling, has many attractive advantages. 

The paper also includes some. further checks on individual uranium and plutonium systems eiqieriments and investigates the limiting concentrations for k - 1 for mixed fuels and for variations Of Pu content in plutonium systems 1... 

The calculation route has also been applied in a validation program induding correlations made with Hanford critical uranium/plutonium solution systems as well as arrays of fuel pins in uranyl nitrate solution (Table I). The results... 

Shibata, A. Kaji, N. Nakahara, M. Yano, K. Tayama, T. Nakamura, K Washiya, T. Myochin, M. Chikazawa, T. Kikuchi, T. (2009). Current Status on Research and Development of Uranium Crystallization System in Advanced Aqueous Reprocessing of FaCT Project, Proceedings of International Conference on The Nuclear Fuel Cycle Sustainable Options Industrial Perspectives (GLOBAL 2009), pp. 151-157, Paper 9154, Paris, France, September 6-11, 2009 Staritzky, E. Truitt, A. L. (1949). Optical and Norphological Crystallography of Plutonium Compounds, LA-745, Los Almos National Laboratory, Los Alamos, New Mexico, USA... 

Also, the MBRU-12 targets the possibility of being used as an element of the multi-component nuclear power system with optimized nuclide flows between the elements. Specifically, the MBRU-12 targets to use mixed uranium-plutonium fuel for core loading. 

As a solvent for liquid-metal fuels, bismuth is a natural choice because it dissolves uranium and has a low cross section for thermal neutrons. As a result, research work at Brookhaven National Laboratory has centered on bismuth-uranium fuels. Other po.s.sible liPlutonium System (LAIMPRE) [14] and dispersions of uranium oxide in liquid metals, NaK [15] or bismuth [10]. The limited solubility, of uranium in bismuth is trouble.some in some designs. More concentrated fuels can be obtained by using slurries or dispersions of solid uranium compounds in bismuth. Among the. solids which have been suggested are intermetallic compounds [10] uranium oxide [10], uranium carbide, and uranium fluoride. Use of a dispersion avoids the limited concentration but introduces other problems of concentration control, stability, and erosion. 

The CEFR is a sodium cooled, bottom supported 65 MW(th) experimental fast reactor fuelled with mixed uranium-plutonium oxide (the first core, however, will be loaded with uranium oxide fuel). Fuel cladding and reactor block structural materials are made of Cr-Ni austenitic stainless steel. It is a pool type reactor with two main pumps, and two loops for the primary and secondary circuit, respectively. The water-steam tertiary circuit has also two loops, with the superheated steam collected into one pipe that is connected with the turbine. CEFR s has a natural circuit decay heat removal system. 

The Hanford N Reactor. The Hanford N reactor was built in 1964 for purposes of plutonium production during the Cold War. It used graphite as moderator, pierced by over 1000 Zircaloy 2 tubes. These pressure tubes contained slightly enriched uranium fuel cooled by high temperature light water. The reactor also provided 800 MWe to the Washington PubHc Power Supply System. This reactor was shut down in 1992 because of age and concern for safety. The similarity to the Chemobyl-type reactors played a role in the decision. 

One of the most Important thermophysical properties of reactor fuel In reactor safety analysis Is vapor pressure, for which data are needed for temperatures above 3000 K. We have recently completed an analysis of the vapor pressure and vapor composition In equilibrium with the hypostolchiometric uranium dioxide condensed phase (1 ), and we present here a similar analysis for the plutonium/oxygen (Pu/0) system. 

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