Systematization of assessment techniques of stress corrosion cracking for in-vessel components and piping in BWR

Kato, Chiaki   ; Yamamoto, Masahiro ; Tsukada, Takashi 

This research was performed through systematization of assessment techniques of SCC in austenitic stainless steel for in-vessel components and piping in BWR in order to develop a technical basis necessary to improve evaluation methods of the stress corrosion cracking (SCC). Recently, discrepancy between laboratory data and field experiences in crack initiation and crack growth rate was reported. JSME appendices for flaw evaluation can conservatively explain the crack growth rate in field experiences, while it is indicated the crack growth rate is slower in field experiences than in the crack growth rate reference curve of JSME. The crack growth rate reference curve would be more conservative in SCC assessment of field experiments. Therefore, a prediction model in crack initiation and propagation is expected in order to explain failure time reasonably and accurately in the crack propagation. On the other hand, it was reported that hydrogen peroxide under radiolysis water accelerated crack propagation. This accelerating factor has not been considered in SCC assessment techniques at present. The objective of this research is to summarize the present situation of SCC assessment techniques and to study issues of the technique from viewpoints of discrepancy between field experiences and laboratory data.