Analysis of damaged welds no. 111 in the PGV-1000 steam generator and damage repair proposals

Reliability of complex facilities, such as nuclear power plants, under construction or in operation is fundamental to the safety of humans and the natural environment. The key reliability-related factors are absence of errors in structural design and calculations, proper selection of materials and the manufacturing technology, quality of the materials used and the onsite welding operations, conditions of operation and in-service inspection.Despite the fact that much attention is given in the course of the NPP design and operation to ensuring reliability, the experience of operation has demonstrated that there is a potential for crack formation in welded joint No. 111 of the PGV-1000 M steam generator. The crack nucleation and growth mechanism has not been yet unambiguously identified.This paper presents the results of a study into the causes for the metal damage in the region of welded joint No. 111 between the hot header and the steam generator vessel's nozzle of Dn1200.