Main screw hole damage repairing method for nuclear power plant reactor pressure vessel

• Main Authors: ZHONG ZHENTANG, DUAN YUANGANG, WANG LI, LIU YANZHANG, HUANG TENGFEI, RAN XIAOBING, HU DAFEN, KUANG YANJUN, JIN LIANG, SUN GUANG, QIU ZHENSHENG
• Format: Patent
• Language: Chinese; English
• Published: 20.09.2019
• Subjects: COMBINED OPERATIONS; MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; OTHER WORKING OF METAL; PERFORMING OPERATIONS; TRANSPORTING; UNIVERSAL MACHINE TOOLS

The invention discloses a main screw hole damage repairing method for a nuclear power plant reactor pressure vessel (RPV). The method comprises the follow steps of 1), carrying out hole expansion treatment on the damaged RPV main screw hole to remove the original thread and the damage defect; 2), adopting automatic pulse tungsten inert gas shielded welding to continuously implement horizontal welding position multi-bead multi-layer welding from bottom to top along the inner wall at the bottom of an RPV main screw hole; and 3), mechanical machining is carried out on the weld metal on the inner wall of the main screw hole, redundant weld metal is completely removed, and after removal is completed, carrying out new thread machining on the weld metal on the inner wall of the main screw hole to obtain a main screw hole meeting the design size requirement. According to the method, the new thread is prepared through welding and machining, so that the severe damage of the main screw hole thread of the RPV can be effe