Method of dismantling reactor pressure vessels

Purpose: To eliminate the requirement of troublesome preparatory works such as water-sealing of throughholes in thermal shielding walls of nuclear reactors, as well as prevent radioactive contaminated range from prevailing after the dismantling of a pressure vessel. Method: Connection portions for pipeways to a reactor pressure vessel are in a fitted watertight manner with water sealing plugs. Then, water is charged in the vessel and pipeways are cut. Then, a cutting tool is inserted into the vessel to cut the vessel circumferentially from the inner circumferential side in water. After most of the cutting process has been completed, the water level is lowered below the cutting line and the residual portion is completely cut in air. Since most part of the cutting work is carried out in water, dross or the like resulted upon cutting can easily be recovered to prevent contamination from prevailing. Then, since water is contained only within the vessel and not to the nuclear reactor thermal shielding walls, it is possible to save such preparatory operations as water sealing between the shielding walls and the pedestal or plugging to the throughholes in the shielding walls. (Yoshino, Y.)