Abstract
The present study examines the potential for the demonstration of fission product transmutation in the experimental fast reactor JOYO at JNC's Oarai Engineering Center. The possibility of creating a highly-efficient transmutation irradiation field of JOYO by loading neutron moderating subassemblies in the reflector region was investigated in a series of scoping calculations. A cluster of reflector subassemblies was replaced with beryllium or zirconium hydride (ZrH1.65) moderated subassemblies. These moderated subassemblies surrounded one central test subassembly that would contain 99Tc or 129I target material. With this modification, a high fast neutron flux can be tailored to epithermal or thermal energies. A comparison of reaction rates among the spectra is made illustrating the integral effects on selected target reactions. The 99Tc transmutation rate achieved was 21.0% using ZrH1.65 and 27.8% using beryllium as moderator. As a result of this study, basic characteristics of LLFP transmutation in JOYO using relevant moderator materials were clarified and the future feasibility was shown.
