Pressure Tube Fitness-for Service Evaluation of Flaws

Abstract

Pressure tubes develop flaws in operation from several flaw formation mechanisms, such as fretting interaction with foreign material or fuel bundles or local chemical attack. The evaluation of such flaws as potential initiation sites for pressure tube failure is a requirement of the CSA evaluation standard. Detected flaws are evaluated against deterministic acceptance criteria, while the entire reactor core is evaluated using probabilistic methods. This paper discusses implementation of these methods and some practical observations that have arisen in their application.