Abstract
Plutonium-238 ((238)Pu) is a scarce heat-source radioisotope used in nuclear batteries, which is produced by in-reactor irradiation of Americium-241 ((241)Am) or Neptunium-237 ((237)Np). Optimizing the neutron spectrum can improve the production efficiency of (238)Pu, but currently, it is still a lack of knowledge about the optimal neutron spectrum for (238)Pu production. Genetic algorithms and burnup algorithms are combined to identify optimal neutron spectra for (238)Pu 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 (238)Pu production?" and "What is the maximum efficiency for (238)Pu 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 (238)Pu. Moreover, these results find that the production method of in-reactor irradiation (237)Np not only has a higher yield but also achieves a higher purity of (238)Pu than that of in-reactor irradiation (241)Am, which conflicts with the traditional experiences, providing with previously unknown insights and helping break through the efficiency limit of traditional methods, maximizing (238)Pu production.