Concept of a small fast breeder reactor system capable of transmuting MA and LLFP

Abstract

The issues of nuclear power systems are the effective use of uranium resources and the reduction of radioactive wastes. Important radioactive wastes are minor actinides (MA : 237Np, 241Am, 243Am, etc.) and long-lived fission products (LLFP : 129I, 99Tc, 79Se, etc.). The purpose of this study was to construct a system that simultaneously achieves the breeding of fissile materials and the transmutation of MA and LLFP using small fast reactors. Transmutation was achieved by loading the innovative Duplex type MA-containing fuel in the core region and the LLFP-containing moderator in the first layer of the radial blanket. Breeding of the entire small fast reactor system was achieved by combining two small fast reactors: one for transmutation and the other for breeding. As a result, it was clarified that in this small fast reactor system, a breeding ratio of approximately 1.03 was obtained, and support ratios (SRs) of 2 or more were achieved for MAs and LLFPs.