Recent observations of cracks in large diameter BWR piping: analysis and remedial actions

Since the introduction of the first commercial boiling water reactor (BWR), incidents of intergranular stress corrosion cracking (IGSCC) in the weld-heat-affected zones of austenitic stainless steel piping have occurred. Early incidents of pipe cracking were confined to small-diameter lines of 100 mm (4 inch) or less. In time, larger diameter lines were also subject to the phenomenon of IGSCC and in 1978 the first incident in a 610-mm (24-inch) 304 stainless steel pipe of the Gundremmingen BWR Block A was reported. This plant, a BWR model 1, had been in operation since 1967 and was one of the older operating units. Further incidents of cracking in pipes greater than 508 mm (20 inch) in diameter did not occur until 1982. Subsequently, a number of other boiling water reactors reported incidents in large-diameter lines. The purpose of this paper is to review these recent incidents and the remedial actions taken by the utility industry