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Optimal Neutron Spectrum Database for In-reactor 238Pu Production
Qingquan Pan1, Xiaojing Liu1, Yun Cai2
1School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Abstract:
Plutonium-238 (238Pu) is a scarce heat-source radioisotope used in nuclear batteries, which is produced by in-reactor irradiation of Americium-241 (241Am) or Neptunium-237 (237Np). Optimizing the neutron spectrum can improve the production efficiency of 238Pu, but currently, it is still a lack of knowledge about the optimal neutron spectrum for 238Pu production. Genetic algorithms and burnup algorithms are combined to identify optimal neutron spectra for 238Pu production under various irradiation times and flux levels, and build an optimal neutron spectrum database, which answers the questions "What is the optimal neutron spectrum for 238Pu production?" and "What is the maximum efficiency for 238Pu production" once and for all. This database can be referred to for determining the optimal neutron spectrum, guiding the neutron spectrum regulation process to improve the yield of 238Pu. Moreover, these results find that the production method of in-reactor irradiation 237Np not only has a higher yield but also achieves a higher purity of 238Pu than that of in-reactor irradiation 241Am, which conflicts with the traditional experiences, providing with previously unknown insights and helping break through the efficiency limit of traditional methods, maximizing 238Pu production.
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