Core concept of simultaneous transmutation of six LLFP nuclides using a fast reactor

Abstract

The core concept of simultaneous transmutation of six long-lived fission products (LLFP: 79Se, 93Zr, 99Tc, 107Pd, 129I, and 135Cs) was investigated using MONJU fast reactor by maintaining all 6 LLFP nuclides support ratios at 1 or greater. By loading the six LLFP nuclides with the partial use of moderator into the blanket, the shield, the axial blanket, a part of gas plenum region and the axial shield, the effective half-lives of the LLFP nuclides were greatly reduced while maintaining the support ratios at 1 or greater. A new transmutation system for the six LLFPs based on a fast reactor core was constructed. It was also found that the basic core characteristics of the LLFP loaded core: the sodium void coefficient, Doppler coefficient and power distribution, did not differ greatly from those of normal conventional fast reactors.