A historical perspective on understanding IASCC

Irradiation assisted stress corrosion cracking (IASCC) emerged over six decades ago with cracking of stainless steel fuel cladding, and it subsequently affected a wide range of components at much lower fluences than the fuel cladding. It was originally viewed as a distinct and mysterious phenomenon, with many hundreds of possible radiation effects playing a role. Oddly, given this complexity, for decades there was misplaced hope that minor compositional variations – such as reduced S or P – would make a dramatic difference. In the 1980s, common dependencies in irradiated and unirradiated materials were observed both in plant experience and laboratory data. Knowledge of SCC in unirradiated materials provided hypotheses of the key irradiation contributions, which led to critical tests of the ideas. Simplistic, short term tests gave way to more sophisticated and sensitive experiments that have had a big impact on our understanding of IASCC, which remains incomplete.