Abstract
A Non-mandatory Appendix L, of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code Section XI, was investigated to learn how flaw tolerance evaluation was treated in the code rules. It becomes possible to operate a nuclear power plant continuously by applying integrity assessment given by the Appendix L based on fatigue crack growth evaluation when a cumulative usage factor exceeds the allowable limit in design. Systematic and methodological ways of iniroduction of environmental fatigue and flaw tolerance concept into the Japanese code rules were considered with reference to the investigation result of ASME Section XI Appendix L.
