Method to Reduce Long-lived Fission Products by Nuclear Transmutations with Fast Spectrum Reactors

作者：Chiba Satoshi^*; Wakabayashi Toshio; Tachi Yoshiaki; Takaki Naoyuki; Terashima Atsunori; Okumura Shin; Yoshida Tadashi

来源：Scientific Reports, 2017, 7(1): 13961.

DOI：10.1038/s41598-017-14319-7

Transmutation of long-lived fission products (LLFPs: Se-79, Zr-93, Tc-99, Pd-107, I-129, and Cs-135) into short-lived or non-radioactive nuclides by fast neutron spectrum reactors without isotope separation has been proposed as a solution to the problem of radioactive wastes disposal. Despite investigation of many methods, such transmutation remains technologically difficult. To establish an effective and efficient transmutation system, we propose a novel neutron moderator material, yttrium deuteride (YD2), to soften the neutron spectrum leaking from the reactor core. Neutron energy spectra and effective half-lives of LLFPs, transmutation rates, and support ratios were evaluated with the continuous-energy Monte Carlo code MVP-II/MVP-BURN and the JENDL-4.0 cross section library. With the YD2 moderator in the radial blanket and shield regions, effective half-lives drastically decreased from 106 to 102 years and the support ratios reached 1.0 for all six LLFPs. This successful development and implementation of a transmutation system for LLFPs without isotope separation contributes to a the ability of fast spectrum reactors to reduce radioactive waste by consuming their own LLFPs.

• 出版日期2017-10-24