Evaluation of technetium transmutation in the experimental fast reactor “JOYO”

In this study the effectiveness of transmutation for the long lived fission product technetium-99 in the experimental fast reactor “JOYO” is evaluated. The cluster of reflector subassembly was replaced with a new moderator and target subassembly. The Beryllium metal is selected as moderator. The calculation of Ruthenium concentration evolution under irradiation was performed using ChainSolver 2.20 code. For 140 full power irradiation days, the transmutation yield is 30% and 87% in the radial reflector and target subassembly, respectively. The approximation used for the transmutation calculation is the assumption that the influence of change in irradiated materials structures on the reactor operator mode characteristics is insignificant.