Aiming for improved steam generator reliability in Japan

As of October 1990, 17 pressurized water reactors (PWRs) were operating in Japan and six others were under construction. Steam generator tubes in the operating reactors have experienced a great deal of degradation. In Japan a nuclear plant must be stopped immediately if any small leakage is detected in steam generator tubes. Such a forced outage increases the cost of inspection and repair, lowers availability and contributes to a loss of public confidence. Thus great efforts are made to prevent steam generator leakage by carrying out strict inspection, repair and preventive maintenance. (author)