Plutonium-power reactors characteristics

Origins. Most of the radioactive waste at SRP originates in the two separations plants, although some waste is produced in the reactor areas, laboratories, and peripheral installations. The principal processes used in the separations plants have been the Purex and the HM processes, but others have been used to process a variety of fuel and target elements. The Purex process recovers and purifies uranium and plutonium from neutron-irradiated natural uranium. The HM process recovers enriched uranium from uranium—aluminum alloys used as fuel in SRP reactors. Other processes that have been used include recovery of and thorium (from neutron-irradiated thorium), recovery of Np and Pu, separation of higher actinide elements from irradiated plutonium, and recovery of enriched uranium from stainless-steel-clad fuel elements from power reactors. Each of these processes produces a characteristic waste. 

The application of the mixed uranium-plutonium fuel in power reactors requires assurance of safe transport of semifinished items, fuel elements, and fuel bundles (FB). To research various aspects of safety, it is necessary to take into account that the thermal and radiation characteristics and criticality parameters of MOX fuel are higher than the characteristics of fuel on a basis of uranium dioxide. 

Over the more than 40 years since the first nuclear fission reactor was constructed numerous designs of reactor have been evolved by variation of the basic parameters such as fuel type, moderator, and coolant. One possible classification is by intended use, e.g., research, plutonium production, electricity generation, or propulsion units for submarines or surface ships. In this chapter we will concentrate on power reactors, both on account of their practical importance and because of the complexity in engineering design introduced by the need to convert the energy released by nuclear fission into a mechanical or electrical output. Many of the characteristics of the various reactor types have been touched on in earlier chapters, but the objective in the present chapter is to provide a systematic summary of the main classifications of reactor prior to the more detailed descriptions to be given in the following chapters. 

The projections are based on a recent forecast (Case B) by the Energy Research and Development Administration (ERDA) of nuclear power growth in the United States (2) and on fuel mass-flow data developed for light water reactors fueled with uranium (LWR-U) or mixed uranium and plutonium oxide (LWR-Pu), a high temperature gas-cooled reactor (HTGR), and two liquid-metal-cooled fast breeder reactors (LMFBRs). Nuclear characteristics of the fuels and wastes were calculated using the computer code ORIGEN (3). 

The project of BRUS-150 integral type reactor of 500 MW thermal power and 150 MW electric power has been developed. The core, steam generators, pumps and all lead-bismuth loops are located in the reactor vessel, so that leak-proof vessel contains total amount of lead-bismuth. BRUS-150 reactor can be also used for transmutation of minor actinides accumulated in WWER type reactors and for utilization of weapon grade plutonium (for the main characteristics -see Table 2.2)... 

A study of this type must take several factors into account, such as evaluation of the plutonium produced in terms of the installed nuclear electrical power, and of the e and characteristics of planned nuclear reactors, diemical form, and isotopic composition of the plutonium to be stored, possible storage systems, and safety standards to be adopted (criticality, fire protection, shielding, flooding, heat elimination, earthquakes, etc.). The e q>ectations of the Spanish Electricity Plan have been used as a basis for this study, which assumes an. installed nuclear electrical power of 23,500 MW(e) by the year 1985. 

During the irradiation of a standard fuel like UO2 oxides or MOX, a significant part of nuclear reactions are not fission reactions, but capmre reactions or more complex nuclear transmutations. Thus, in the conrse of time, a part of the isotopes transforms into plutonium Pu, a fissile material which will increasingly contribute to the supply of power. However, some of these reactions will lead to the formation of isotopes difficult to recover (isotope pairs of Pu, Am and other minor actinides, etc.), whose accumulation would cause major concern. The fission of these isotopes can be achieved by irradiation in certain reactors whose neutron characteristics will be adapted to this functioa We must however avoid the recreation of similar isotopes as and when they are burnt . This could lead to striving for fuel designs where the fissile material is dispersed not in the UO2 oxide, but in a neutronically inert matrix. 

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