Dry processing device

Purpose: To extend the safety limit for the drying storage by drying spent fuels and the storage atmosphere. Constitution: Spent nuclear fuel assemblies are contained within a drying device having a structure capable of withstanding the reduced pressure. The pressure is reduced by the device by way of a valve. Steams generated upon pressure reduction are subjected to air-liquid separation in a condensator and the condensates are discharged from the draining system. Further, airs are always sent from an air reservoir by way of a valve to a humidity conditioner. Then, the water concentration is adjusted about to less than 100 ppm and the condensates are discharged through the draining system. Thus humidity-conditioned dry airs are sent into the drying chamber by way of the valve upon returning to the normal pressure. In this way it has been found that when the assemblies are stored in the dry air, degradation in the materials due to the corrosions of cladding tubes can be avoided and the working life can be increased by about five times as compared with the case of storage in humid airs. (Takahashi, M.)