Design and verification of shielding for the advanced spent fuel conditioning process facility

An Advanced spent fuel Conditioning Process Facility (ACPF) has recently been constructed by a modification of previously unused cells. ACPF is a hot cell with two rooms located in the basement of the Irradiated Materials Experiment Facility (IMEF) at the Korea Atomic Energy Research Institute. This is for demonstrating the advanced spent fuel conditioning process being proposed in Korea, which is an electrolytic reduction process of spent oxide fuels into a metallic form. The ACPF was designed with a more than 90 cm thick high density concrete shield wall to handle 1.38 PBq (37,430 Ci) of radioactive materials with dose rates lower than 10 muSv h in the operational areas (7,000 zone) and 150 muSv h in the service areas (8,000 zone). In Monte Carlo calculations with a design basis source inventory, the results for the bounding wall showed a maximum of 3 muSv h dose rate at an exterior surface of the ACPF for gamma radiation and 0.76 muSv h for neutrons. All the bounding structures of the ACPF were investigated to check on the shielding performance of the facility to ensure the radiation safety of the facility. A test was performed with a 2.96 TBq (80 Ci) 60Co source unit and the test results were compared with the calculation results. A few failure points were discovered and carefully fixed to meet the design criteria. After fixing the problems, the failure points were rechecked and the safety of the shielding structures was confirmed. In conclusion, it was confirmed that all the investigated parts of the ACPF passed the shielding safety limits by using this program and the ACPF is ready to fulfill its tasks for the advanced spent fuel conditioning process.