Considering one U-238 absorbs a neutron and after two-beta decays resulting in plutonium-239, the neutron capture rate of U-238 is calculated to be nearly 90% of the fission rate for U-235, largely due to the high concentration of U-238 (>95% of the loading uranium fuel).ĭuring normal reactor operation, a U-235 nucleus continuously absorbs a thermalized neutron and releases on average 2.43 neutrons. Therefore, a light water reactor generates 1.85% (0.8% + 1.05%) plutonium during reactor operation. This suggests that 1.05% of plutonium-239 is burned during reactor operation (one-half of 2.1% and one-third of the total). This compares with 0.9% of U-235 and suggests that the fission reaction rate for plutonium-239 is approximately 10% faster than that of U-235 in a typical commercial thermal nuclear reactor.Ĭonsidering light water reactors, U-235 is enriched to approximately 3% where 2.1% of it is burned during reactor operation. Spent nuclear fuel commonly contains about 0.8% of plutonium-239. Fission of plutonium-239 provides about one-third of the total energy produced in a typical commercial nuclear power plant. Plutonium present in reactor fuel can absorb neutrons and fission just as U-235 can. In any operating nuclear reactor containing U-238, some plutonium-239 will accumulate in the nuclear fuel due to continuous neutron capture by U-238 followed by two-beta decays. Also, the neutron energy spectrum resulting from dense D-D plasma core fusion is much softer than D-T fusion neutron source, hence the probability of (n, p) (n, α) backward decay reaction paths will be smaller and the conversion efficiency will be elevated. However, if 20% beryllium of nuclei density is added to the convertor blanket, the efficiency of the conversion process can be significantly increased. Results show that this could be achievable within a decade, given an appropriate fusion source. This recognizes that emerging fusion technologies may not produce sufficient net energy output to justify stand-alone applications, yet may be commercially viable for breeder transmutation or hybrid fusion-fission reactor concepts proposed herein to dispose of nuclear wastes and long life high radioactive fission products remaining in shutdown nuclear power plants. This article proposes a general framework for the conversion of U-238 and Th-232 utilizing fusion-produced neutrons. Received 16 July 2014 revised 30 August 2014 accepted 14 September 2014 This work is licensed under the Creative Commons Attribution International License (CC BY). 2Southwestern Institute of Physics, Chengdu, ChinaģInstitute of Nuclear Science and Technology, Sichuan University, Chengdu, ChinaĮmail: * © 2014 by authors and Scientific Research Publishing Inc.
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