DEVELOPMENT OF ENTERGY FLEET PSA GUIDANCE DOCUMENTS FOR MODEL DEVELOPMENT

摘要

Entergy Nuclear is a large diverse nuclear fleet that consists of nine nuclear sites and two regional headquarters offices. The PSA models for these plants were generally developed and maintained separately until the early 2000's. Therefore, much of the organizational learning and best practices from one site were not implemented at another site due to time constraints, plant demands, lack of communication, or lack of expertise. In 2007, Entergy Nuclear management requested that guidelines be developed to standardize PSA processes and to better address the requirements of the ASME PSA Standard. Twelve guidelines were scheduled to be developed. These guides were based on the nine major Full Power Internal Events (FPIE) ASME Standard elements with additional guidelines for Loss of Offsite Power analyses, Risk Monitor development, and Uncertainty Analysis. The majority of these guidelines were scheduled to be completed by the end of 2008. These guidelines had to be developed while still meeting the model update schedules, IPEC License Renewal, and various plant PSA applications. In addition to the compressed schedule for developing these guidelines, the completion of these reports were complicated by other factors. The amount of detail necessary for the guidelines was a significant challenge. More detail would likely force some plants to make major changes to the models or the documentation with unacceptable impacts on model update schedules. However, some amount of detail is necessary to help new PSA engineers in performing these tasks. The PSA software tools were generally consistent across the sites (all sites use CAFTA for fault tree modeling). However, other methodologies and tools varied throughout the fleet. These variations are acceptable within the ASME Standard and had to be accounted for in the guidelines. Despite the compressed schedule and the significant challenges and compromises necessary, the PSA guidelines were able to be completed and have been useful to both the experienced and new PSA engineers across the Entergy Nuclear fleet. The guideline development has also fostered more cooperation between the two regional offices and has led to more discussions and sharing of information across the fleet.