Abstract: A method of repairing a vessel bottom head penetration of a nuclear reactor is presented, said penetration comprising a tube fastened to the internal wall of the vessel bottom head by an internal weld bead and emerging outside the vessel bottom head, forming a groove. The method consists inter alia in preparing a mock-up representative of the vessel bottom head penetration to be repaired and in depositing this mock-up on site in an irradiation-free zone, in fastening two half-inserts to this mock-up in the groove, each half-insert having a profile corresponding to the half-profile of the groove, in forming, again on this mock-up, automatically and by remote control, a weld bead in the groove, in carrying out a dimensional check and, after validation of this weld bead, in carrying out the steps of fastening the two half-inserts and forming a weld bead automatically, directly in the groove of the vessel bottom head penetration to be repaired.

Abstract: The invention relates to a method of repairing a vessel bottom head penetration of a nuclear reactor, said penetration comprising a tube (10) fastened to the internal wall of the vessel bottom head (1a) by an internal weld bead (11) and emerging outside the vessel bottom head, forming a groove (15). The method consists inter alia in preparing a mock-up representative of the vessel bottom head penetration to be repaired and in depositing this mock-up on site in an irradiation-free zone, in fastening two half-inserts (30a, 30b) to this mock-up in the groove, each half-insert having a profile corresponding to the half-profile of the groove, in forming, again on this mock-up, automatically and by remote control, a weld bead (35) in the groove (15), in carrying out a dimensional check and, after validation of this weld bead (35), in carrying out the steps of fastening the two half-inserts and forming a weld bead automatically, directly in the groove (15) of the vessel bottom head penetration to be repaired.