Structural Integrity Assessment of a Reactor Pressure Vessel Using State-of-the-Art Methodologies—A Case Study

Abstract

Structural integrity assessment of reactor pressure vessel (RPV) has been carried out for design life of the reactor using state-of-the-art methodologies. Irradiation damage is the governing material degradation for core belt region of RPV, and it is quantified based on the surveillance program. Structural integrity assessment has been carried out for the postulated flaw at the core belt region to demonstrate the protection of the vessel against catastrophic failure, plastic collapse, and tearing instability. Protection against catastrophic failure has been demonstrated based on the linear elastic fracture mechanics (LEFM) approach. Stable crack extension and flaw stability due to ductile tearing have been demonstrated based on J-integral and failure assessment diagram (FAD). Limiting values of flaw depth and flaw length have been evaluated to demonstrate the protection against all failure modes. Further, leak-before-break (LBB) criterion has been adopted to demonstrate the defense in depth philosophy. Limiting flaw length to depth ratio has been quantified in order to demonstrate leak-before-break criterion. The assessment has demonstrated the healthiness of the vessel for safe operation.