“Mechanical Methods of Improving Resistance to Stress Corrosion Cracking in BWR Piping Systems” J. Abel, J. Titrington, R. Jordan, J. S. Porowski, W. J. O’Donnell, M. L. Badlani, and E. Hampton, SMIRT Post Conference, Lausanne, Switzerland, August, 1987.
Considerable data and a variety of procedures for dealing with matters related to the BWR pipe cracking problem have been developed, both here and abroad. Mitigation technologies such as stress improvement, new material and water chemistry control have become an integral part of the solution to IGSCC issue as the interaction of tensile stress, material susceptibility, and locally conducive environment, the three causative factors contributing to IGSCC, have become understood. The stress-related crack mitigation measures include IHSI (Introduction Heating Stress Improvement) Heat Sink Welding, Last Pass Heat Sink Welding, and MSIP (Mechanical Stress Improvement Process). The water chemistry-related crack mitigating measures include oxygen control and hydrogen addition, while the material-related crack mitigation measures include corrosion-resistant cladding solution heat treatment and the use of Type 316 nuclear grade stainless steel. This paper discusses the mechanical methods that have been developed for dealing with the stress corrosion cracking in BWR’s. These include MSIP and Pipelock.