Spent fuel storage device for HTGR type reactor

In a HTGR type reactor, since spent fuels contain a great amount of nuclear materials, they require careful handling and safety designs are demanded for spent fuel storage facilities. In addition, as the power is increased, the storage volume is also increased and low cost is required. Then, fuel rods and graphite blocks of spent fuels are separated and only the fuel rods are stored in the spent fuel storage facility in a reactor building while the graphite blocks are discarded. Further, the storage device comprises casings for containing a plurality of fuel rods, racks for containing a plurality of the casings and a pool for containing a plurality of the racks and water. Since the graphite blocks contain less radioactivity and can be processed as wastes, the wastes to be stored is reduced by about 30% by weight and about 60% by volume. Accordingly, along with this reduction, it is possible to reduce the size of the storage racks, decrease the storage space, decrease shieldings and reduce the weight of supporting structure. (N.H.)