Patent ID: 7971330

Claim:
A Method of repairing a vessel bottom head penetration of a nuclear reactor, said penetration comprising a tube fastened to an internal wall of the vessel bottom head by an internal weld bead and emerging outside the vessel bottom head, forming with the external wall of said vessel bottom head, a groove, wherein the method comprises the following steps: after having observed, on the tube and on the outside of the vessel bottom head, a deposit of boron indicating a leak through the internal weld bead, a mock-up representative of the vessel bottom head penetration to be repaired and comprising a vessel bottom head portion and a tube forming, with the external wall of said portion, a groove, is prepared and this mock-up is placed on site in an irradiation-free zone; two half-inserts are fastened to this mock-up in the groove, each half-insert having a profile corresponding to the half-profile of the groove; a weld bead is formed, again on this mock-up, automatically and by remote control, in the groove and a good distribution of welding passes is verified; a dimensional check of the weld bead is carried out on the mock-up and after this weld bead has been validated; the boron on the tube of the vessel bottom head penetration to be repaired is removed, by brushing it off; and the step of fastening the two half-inserts and then the step of forming a weld bead, automatically and by remote control, directly in the groove of the vessel bottom head penetration to be repaired are carried out.