Materials Science and Engineering

Biography

Biography: Masaki Ozawa

Abstract

The spent nuclear fuel (SF) and high-level liquid waste (HLLW) must no longer be radioactive waste but a potential vein of rare metal. It is therefore quite natural that such non or less radioactive fission products (FPs) as Mo, Pd, In and REE (La, Nd, Dy, etc.) in SF or HLLW should be recovered and utilized as the secondary resource. Pd-Ru-Rh-TcO₂-based multi-element deposits from simulated HLLW by under-potential deposition (UPD) showed high catalytic reactivity for electrolytic H₂ production, and thereby being the substitute material to Pt electrode [1]. In Après ORIENT research [2], initiated in 2011 at Tokyo Tech, the program relies on the extensive transmutation of FPs in the fast reactor by neutron capture reaction followed by β^- decay like, _ZFP^A (n,γ ) _Z FP^A+1 → _Z+1NRM^A+1 + β^-_, where reloaded highly radioactive _ZFP^A are expected to turn to be stable or very short-lived nuclear rare metals, _Z+1NRM^A+1. Among 40 elements, Ba/La, Pr/Nd, Gd/Tb/Dy, Tc/Ru, and Rh/Pd are the most promising as transmutation pair of _ZFP^A/ _Z+1NRM^A+1 under the various points of resourceability [3]. Although non FPs pair, W/Re calls geopolitical and material attentions with creation of anti-high temperature superalloy. By applying a ZrD₂ moderator alternating to ZrH₂, an isotope fraction of radioactive Re¹⁸⁷ can be decreased to the less level than that of natural Re [4].