EVALUATION OF THE CUMULATIVE IMPACT OF PENDING MODEL CHANGES TO ADDRESS MSPI FAQ 14-01 REQUIREMENTS

摘要

FAQ 14-01 to NEI 99-02 Rev. 7 (Regulatory Assessment Performance Indicator Guideline) was approved in 2014. The new guidelines require that pending model changes that cannot be incorporated into a revision to the site PRA model of record prior to the next reporting quarter should be assessed consistent with the PRA Configuration Control program. The guideline further states that the configuration control program supporting the MSPI should contain a process that ensures that the cumulative impact of pending changes is considered. Pending model changes to be considered for MSPI are those related to implemented plant design and operational changes, identified errors in the PRA model, and F&Os characterized as findings for designed ASME standard supporting requirements. The overall goal of a licensee in addressing this guideline is to ensure that all pending model changes are assessed for their impact on MSPI in an integrated fashion while at the same time limiting the analysis burden associated with this requirement. This paper describes the systematic approach developed for a single unit BWR for addressing these requirements. The approach utilized relies upon a robust screening evaluation to filter modeling issues that are not applicable to the requirement; the results of this screening evaluation are then incorporated into the PRA model configuration control database. Model changes that are found to be applicable are addressed in either a best-estimate or bounding fashion and are incorporated into a "working MSPI model". A quantification, which incorporates the integrated impact of these model changes, is then performed and the effect on the MSPI values is subsequently calculated.