Boiling water reactor pipe cracking: The problem and solution

In recent years plant availability and economics of boiling water reactors have suffered from intergranular stress corrosion cracking in welded Type AISI 304 stainless steel piping systems. In response to this utility problem, a major four-year research and development program jointly sponsored by the Electric Power Research Institute and a Boiling Water Reactor Owners Group was initiated in 1980. The objective of this program is to extend the service lifetime of the piping systems in operating plants and plants under construction. A model for the phenomenon based on the coexistence of weld sensitization, reactor environment, and tensile stress was developed and this has been used to identify engineering solutions for the mitigation of the problem. These are divided into three categories: sensitization, environment and stress. A number of solutions or pipe remedies have been developed, qualified and implemented while others are still in the development phase. To achieve technology transfer, a special facility for the remedy application on piping mock-ups and the training of utility personnel has been established