Abstract: A method of repairing the housing of a control rod driving system of a nuclear reactor, the housing being inserted through the wall of a pressure vessel of the reactor into a cylindrical sleeve secured to the inner surface of the vessel, which housing is jointed by welding to the cylindrical sleeve. The method comprises the steps of: cutting the housing in the circumferential direction of the housing at a position defined between the weld joint and the inner surface of the reactor vessel and surrounded by the cylindrical sleeve, thereby to divide the housing into a first housing part still attaching to the weld joint and another removable housing part; removing the removable other housing part; inserting a second housing part into said cylindrical sleeve through the wall of the nuclear reactor vessel; and uniting the first housing part and the second housing part by welding thereby to form a new housing for the control rod driving system.

Abstract: In a method and a system for inspection of the inside of a nuclear reactor vessel in which an inspection device for inspecting a defect in a nuclear reactor vessel is so moved by a drive/control device as to permit inspection of a part to be inspected in the reactor vessel, and the presence or absence of defect in the reactor vessel is judged based upon information from the inspection device in the course of the above-mentioned movement of the inspection device; the movement of the inspection device is pursued and monitored by monitor means, and the movement of the inspection device is suppressed when an abnormality in the movement of the inspection device is judged based upon information from the monitor means, to avoid the abnormal movement.

Abstract: In a method of correcting a distorted pipe end to an original substantially true circular cross-section, external loads are applied to the outer peripheral surface of the pipe adjacent to the end thereof to forcibly deform the pipe end to the substantially true circular cross-section. The external loads are maintained to keep this substantially true circular cross-sectional shape while an internal pressure is applied to the inner peripheral surface of the pipe end until a circumferential stress produced in the pipe reaches an amount which exceeds the yield stress of the pipe to give a radial permanent deformation to the pipe for thereby producing a circumferentially uniformly distributed residual stress in the pipe.

Abstract: Method for controlling an automatic pipe welder is disclosed. In the automatic welder which requires remote control, welding conditions for butt welding pipes are stored and an actual joint geometry or groove shape is sensed. From signals relating to the stored welding conditions and the sensed groove shape, a control command signal in actual welding is produced to effect welding under an optimum condition. On the other hand, an arc condition at an actual welding point and a melting condition of a metal are monitored and displayed to modify the welding conditions in accordance with the monitored condition to control the automatic pipe welder.