LSDS development for isotopic fissile assay in used fuel

The lead slowing down spectrometer (LSDS) is under development for analysis of isotopic fissile material contents in recycled fuel material and spent fuel at KAERI. In spent fuel, the content of uranium and plutonium isotopes is various depending on the burnup history. Normally, an indirect mechanism is used for the content assay of isotopic fissile with the help of burnup code. However, an indirect methodology has a limitation in getting the accurate fissile content. For future nuclear energy system development, the pyro processing is under development to recycle fissile in spent fuel. LSDS uses external neutron source to get the direct fission signal from each fissile material. The source neutron slowed down continuously in the lead medium and induced fissile fission in fuel. Each fissile material has dominant fission characteristics in the resonance energy region and below resonance. In that energy region, fission measurement has a direct relationship of fissile mass. LSDS does not need burnup history information or burnup code help. The detector geometry and sensitivity simulation was performed. The source neutron production methodology was decided and several parameters were determined. The source system consists of target and electron accelerator facility. The neutron is produced by (e, g) (g, n) reaction. The fissile fission will be measured in the spectrometer