Design of Lead Slowing Down Spectrometer for Spent Fuel Fissile Assay

In order to reuse fissile materials in PWR spent fuel, SFR linked with pyro chemical process is being developed in Korea. The pyro process produces uranium-TRU (mainly plutonium) mixture with some fission products. The fissile content analysis is very important in quality assurance of the fabricated fuel and safety of the reactor operation. Lead slowing down spectrometer (LSDS) is being developed in KAERI to analyze isotopic fissile material content in product of pyro process. Several sensitivity calculations were performed. On the detection sensitivity, 1st layer detectors have ~60% detection efficiency. Based on the designed geometry, the resolution was examined. Target was optimized to produce neutrons, ~1012 n’s/sec. A coolant effect was investigated on the neutron yield. Additionally, an accurate fissile material content will increase international transparence and credibility for the reuse of PWR spent fuel.