Damage Evaluation and Life Extension of Structural Components

Abstract

This paper describes an approach to life prediction in which critical elements of major structural components are continuously monitored by appropriate damage indicators for structural damage, and, based on the indicated damage state, an on-line assessment is made of the remaining life. Concurrently alternative corrective measures can then be assessed and, if the life has been found wanting, appropriate actions taken. The process is viewed as a continuous one whereby the current remaining life of critical elements is known as the plant ages. The need for applying such procedures becomes increasingly important as some of our major structures approach their design life and concerns arise regarding retirement and replacement versus life extension. Important elements of this approach include definitions of damage, appropriate damage monitors, damage assessment, life prediction, and conseqeunces of corrective action. This paper treats these elements in the context of past history and current programs associated with pipe cracking in nuclear power plants.