Feasibility study of nuclear transmutation by negative muon capture reaction using the PHITS code

Abe, Shinichiro   ; Sato, Tatsuhiko   

Nuclear transmutation has been investigated to reduce long-lived fission products (LLFPs) in high level radioactive wastes. However, the nuclear transmutation is difficult for some LLFPs (e.g., Sr, Sn and Cs) having small cross-sections of fission and neutron capture. Negative muon is examined to be applied for the nuclear transmutation. Low energy negative muon is captured on an atom, and then it can decay or be further captured on its nucleus. When negative muon is captured on nucleus, some light particles and residual nucleus are produced. Negative muon capture process has been implemented into latest version of PHITS. In this study, we studied the feasibility of nuclear transmutation by negative muon capture reaction for LLFPs using PHITS. Negative muon capture reaction on 90Sr is simulated. It is found that 94% of negative muons are captured on nucleus, and 66% of Sr become stable nuclides or radioactive nuclides having less than 20 days. It is also found that 15% of Sr become Rb having longer half-life than that of Sr.