Verification of Fitness-for-Service Prediction Methodologies

The U.S. Department of Energy's Idaho National Engineering Laboratory (INEL) has a substantial interest in predictions for fitness-for-service as well as for lifetime extension. The ability to predict fitness-for-service is applicable to making initial lifetime predictions; making a repair, replace, or continue to operate decision when a defect is found that exceeds applicable codes and evaluating the ability to extend the lifetime of structural components. A major desire is that these prediction methodologies be sufficiently conservative to eliminate premature failures; thus, providing the safety required by the public and plant personnel as well as protecting the environment. But these predictions must not be overly conservative so that structural components are replaced/repaired too soon. The above two requirements are often balanced with the consequences of failure. Situations where the consequences are severe may require additional conservatism unless verified predictive techniques exist.