Patent ID: 9070485
Filing Date: 2015-06-30
Classification: B23P,G21C,Y02E,Y10T

Abstract:
1. A method for repairing a reactor vessel covered with cooling water, comprising: lowering a tubular frame of which an interior is in an air environment having a bottom board into the cooling water; setting a lower portion of said tubular frame in said reactor vessel while said interior of the tubular frame having said bottom board is in said air environment; and repairing said reactor vessel, wherein a counter weight for canceling out buoyancy occurred in the step for lowering said tubular frame into the cooling water is provided at said frame, said frame is formed by a platform set at an interior of said reactor vessel and cylindrical containers connected and laminated on said platform, and said platform is formed by a substantially cylindrical shaped sidewall of which an outer diameter is smaller than an inner diameter of said reactor vessel and the bottom board for closing a lower end of said substantially cylindrical shaped sidewall, wherein an access window for connecting a tubular frame provided at a side wall of said reactor vessel is formed at said substantially cylindrical shaped sidewall and said access window can be sealed by attaching a cover body, wherein said platform comprises a flange portion protruded from an upper end of said sidewall toward an outer peripheral direction and supported by an upper end of said reactor vessel and a sealing element is inserted to a gap between said upper end of said reactor vessel and said flange portion, and wherein a plurality of underwater fastening portions for tightly fastening said flange portion with respect to said upper end of said reactor vessel are provided along a circumferential direction with same interval, wherein each underwater fastening portion comprises: