Fast breeder reactor

Purpose: To restrain vibration of nuclear reactor vessels by preventing local deformation of safety vessels of fast breeder reactors in case of earthquakes. Constitution: The fast breeder reactor comprises supportmembers provided outside around a nuclear reactor, engaging parts which are connected with support members provided inside a safety vessel, and a reinforcing mechanism provided outside around the safety vessel. Providing this reinforcing mechanism outside the engaging part increases the rigidity of the safety vessel to minimize the local deformation of the engaging part in case of earthquakes. That is, vibration of the reactor vessel in case of earthquakes is transmitted to the safety vessel through a key provided in the outer periphery of the reactor vessel and a key receiver provided on the inner periphery of the safety vessel, and further transmitted to the building. On the outer periphery in the key receiving position, a cover is welded, and on the outer periphery of the cover, a box-shaped rib structure as a reinforcing mechanism is provided in an annular form, thereby increasing the natural frequency of the reactor vessel, decreasing earthquake response acceleration, and accordingly improving the safety of the whole plant. (Kawakami, Y.)