Damage tolerance design for thermal fatigue loading. Crack growth behavior under thermal fatigue loading

Thermal fatigue is one of critical problems in nuclear power plants. To prevent crack initiation, JSME has issued a guideline for design. In this study, the feasibility of incorporating crack growth analysis into the design and integrity evaluation was investigated. It was shown that the steep stress gradient near the surface significantly reduced the stress intensity factor of deep cracks. It is concluded that, under thermal fatigue loading, the cracks that are detected in the in-service inspection have already been arrested if they do not penetrate the wall thickness. The crack arrest scenario is a reasonable method of assessing the integrity of cracked components. (author)