Analysis on Transmutation of Long-Lived Fission Product from the PWR Spent Fuel Using a 30-MW(thermal) RSG-GAS Reactor

The use of the RSG-GAS research reactor as a transmutation reactor is analyzed to study its effectiveness for transmuting long-lived fission products (LLFPs), particularly 129I and 99Tc. Both radionuclides selected are assumed as discharged from of a 1000-MW(electric) pressurized water reactor (PWR) spent fuel. If these radionuclides are stored in sustainable geologic disposal, they will require high-cost handling due to their special shielding. In one cycle of PWR1000 operation, the 99Tc produced is 43.7 kg and 129I is 9.5 kg in its spent fuel. Considering reactor safety, the maximum target mass permitted to be transmuted in the RSG-GAS is 3.0 kg for the 99Tc and 5.0 kg for the 129I. In 1 year of (five cycles) operation, the 99Tc and 129I targets would be reduced by 126 and 290 g, respectively. Although it has the potentiality to safely transmute LLFP targets in its core, RSG-GAS requires longer irradiation time (about 20 years) to entirely transmute the targets.

Keywords: Transmutation, long-lived fission products, RSG-GAS research reactor