Plutonium-power reactors

Curium, like americium, is a transplutonium element in which there is renewed interest. These elements are produced in plutonium power reactors and cause many of the long-term radiological and thermal problems associated with reactor waste storage and disposal. It is evident that such problems will become more acute, and a sounder understanding of the basic chemistry of these elements is mandated. 

Monsanto Chemical Company/Union Electric Company, "Plutonium-Power Reactor Feasibility Study" Dow Chemical Company/Detroit Edison Company, "Study of Materials and Power Producing Reactors" Commonwealth Edison Company/Public Service Company, "Report on Power Generation Using Nuclear Energy" Pacific Gas and Electric Company/Bechtel Corporation, "Industrial Reactor Study," Development of Atomic Power File, AEC/DOE. 

Fuel Costs in Dual-Purpose Plutonium Power Reactors... 

Its importance depends on the nuclear property of being readily fissionable with neutrons and its availability in quantity. The world s nuclear-power reactors are now producing about 20,000 kg of plutonium/yr. By 1982 it was estimated that about 300,000 kg had accumulated. The various nuclear applications of plutonium are well known. 238Pu has been used in the Apollo lunar missions to power seismic and other equipment on the lunar surface. As with neptunium and uranium, plutonium metal can be prepared by reduction of the trifluoride with alkaline-earth metals. 

Another safety issue to be considered which might be exacerbated in the reprocessing option is that the plutonium generated in power reactors, called reactor-grade plutonium because it is made up of a variety of plutonium isotopes, contains plutonium-241, which is subject to spontaneous fission (8). The mixture of isotopes makes it extremely difficult to build an effective nuclear weapon. However, an explosive device could be built using this mixture if control of detonation is sacrificed (48). 

In addition, under the Nonproliferation Treaty, which most larger nations have signed, the IAEA monitors plutonium from power reactors so as to detect covert diversion. 

Table 1. Fissile Plutonium Produced in and Separated from Military and Power Reactor Fuel, t...

In plutonium-fueled breeder power reactors, more plutonium is produced than is consumed (see Nuclearreactors, reactor types). Thus the utilisa tion of plutonium as a nuclear energy or weapon source is especially attractive to countries that do not have uranium-enrichment faciUties. The cost of a chemical reprocessing plant for plutonium production is much less than that of a uranium-235 enrichment plant (see Uranium and uranium compounds). Since the end of the Cold War, the potential surplus of Pu metal recovered from the dismantling of nuclear weapons has presented a large risk from a security standpoint. 

Table 4. Isotopic Composition of Plutonium from Thermal Power Reactors — ...

Nuclear power reactors cause the transmutation of chemicals (uranium and plutonium) to fission products using neutrons as the catalyst to produce heat. Fossil furnaces use the chemical reaction of carbon and oxygen to produce CO2 and other wastes to produce heat. There is only one reaction and one purpose for nuclear power reactors there is one reaction but many puiposes for fossil-burning furnaces there are myriad chemical processes and purposes. 

The DOE N-Reactor is one of the plutonium production reactors located on the Hanford Reservation near Richland, Washington. It is graphite moderated, pressurized water reactors that in addition to production of special nuclear materials also provided steam to turbine generators owned by the Washington Public Power Supply System for electric power production. It began op ition in 1 is put into standby status in 1988 and closed because of similarities to Chernobyl. 

Nuclear fuel recycling allows more efficient nuclear fuel usage and less buildup of nuclear waste. Nuclear power reactors are designed to minimize plutonium build up and much of the plutonium that is produced inside the reactor is used during an ordinary fuel cycle. 

In only 30 months, the Manhattan Project built 554 buildings including reactors, separation plants, laboratories, craft shops, warehouses, and electrical substations. The Hanford Site plutonium production reactors (B, D, and F) were rectangular, measured 36 feet long by 28 feet wide by 36 feet high, used 200 tons of uranium metal fuel and 1200 tons of graphite, were water cooled, and operated at an initial power level of 250 million watts (thermal). They dwarfed the reactors at other sites. 

Fissile materials are defined as materials that are fissionable by nentrons with zero kinetic energy. In nuclear engineering, a fissile material is one that is capable of snstaining a chain reaction of nuclear fission Nuclear power reactors are mainly fueled with manium, the heaviest element that occurs in natnre in more than trace qnantities. The principal nuclear energy soiuces are maninm-235, plutonium-239, uranium-233 and thorium. 

Because the isotope uranium-235 is fissionable, meaning that it produces free neutrons that cause other atoms to split, it generates enough free neutrons to make it unstable. When the unstable U-235 reaches a critical mass of a few pounds, it produces a self-sustaining fission chain reaction that results in a rapid explosion with tremendous energy and becomes a nuclear (atomic) bomb. The first nuclear bombs were made of uranium and plutonium. Today, both of these fuels are used in reactors to produce electrical power. Moderators (control rods) in nuclear power reactors absorb some of the neutrons, which prevents the mass... 

Plutonium is the most important transuranium element. Its two isotopes Pu-238 and Pu-239 have the widest applications among all plutonium isotopes. Plutonium-239 is the fuel for nuclear weapons. The detonation power of 1 kg of plutonium-239 is about 20,000 tons of chemical explosive. The critical mass for its fission is only a few pounds for a solid block depending on the shape of the mass and its proximity to neutron absorbing or reflecting substances. This critical mass is much lower for plutonium in aqueous solution. Also, it is used in nuclear power reactors to generate electricity. The energy output of 1 kg of plutonium is about 22 million kilowatt hours. Plutonium-238 has been used to generate power to run seismic and other lunar surface equipment. It also is used in radionuclide batteries for pacemakers and in various thermoelectric devices. 

The radioactive wastes associated with nuclear reactors fall into two categories (1) commercial wastes — the result of operating nuclear-powered electric generating facilities and (2) military wastes—the result of reactor operations associated with weapons manufacture, Because the fuel in plutonium production reactors, as required by weapons, is irradiated less than the fuel in commercial power reactors, the military wastes contain fewer fission products and thus are not as active radiologically or thermally. They are nevertheless hazardous and require careful disposal. 

HEU) or mixed oxide (MOX) fuel containing oxides of uranium and plutonium in commercial nuclear power reactors, in order to dispose of nuclear weapons materials. Other theoretical reactor concepts are also being investigated for disposal of actinides. 

Uranium fuel preparation takes the UF6 and is converted to either (a) aluminum-clad uranium metal for the weapons plutonium production reactors or (b) to Zirconium-clad U02 for electricity production in the light and heavy water power reactor (see Fig. 21.13). 

Two engineering system demonstrations were performed to reduce the uranium-from-ore requirements of LWRs recycle of the plutonium and conversion to the thorium-uranium cycle to achieve thermal breeding. The demonstration phase of the plutonium recycle development was carried out in seven power reactors. Several LWRs originally were started up on the thorium-uranium cycle, and a light... 

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