Japanese contributions to fields of predicting and combating environmentally assisted cracking (EAC) of steels in LWR water

Two major currents of the EAC relevant activities in Japan are reviewed in some chronological manner. One is the studies on the acceleration of fatigue crack growth in LWR. The work was first pioneered early in Japan, and extensive collaborative works have followed interacting with the international activities, which have yielded a clear views on the potential issues of the RPV structural steels used in the domestic NPPs. Another is the development of materials and techniques to combat the stress corrosion cracking of the structural materials in LWR water environment. Extensive collaboration among the government agencies, utilities, industries and academic societies lead the issues to a dramatic solution in rather short period. Both of those two aspects are stressed to have generic significance in the present and future nuclear technology. (author)