GSI-191 Risk Significance Evaluation

Generic Safety Issue 191 (GSI-191) raises a number of issues related to debris generation and emergency recirculation sump performance after an event inside containment that may affect long term core cooling. Since deterministic efforts could not resolve the issues raised, a risk informed approach has been recommended by NRC Commissioners.

We have developed a simplified method to address all issues raised in GSI-191. The method takes advantage of plant-specific tests and analyses, and unites them under one common analysis method to demonstrate the risk level of the impacted sump strainer. Special attention is given to design bases accidents in this context and use of post accident. The results of two application cases have demonstrated that issues can be resolved using this method.