Maintenance Rule Implementation for the Emergency Diesel Generator System

Emergency Diesel Generator (EDG) reliability has long been a major concern in the nuclear power industry. This issue has been evaluated and addressed by the Nuclear Regulatory Commission (NRC) through various regulatory guidance papers. A recent aspect of these efforts allows utilities to remove accelerated EDG testing from their plant Technical Specifications provided they implement the Maintenance Rule for the EDG System.

This paper discusses the key elements and processes involved in developing a program to monitor the effectiveness of EDG maintenance, or in other words, implement the Maintenance Rule for the EDG system. This process is being used in early implementation of the Maintenance Rule for three nuclear generating stations and incorporates guidance provided to the nuclear industry in Regulatory Guide (RG) 1.160, “Monitoring the Effectiveness of Maintenance at Nuclear Power Plants,” [1] and NUMARC 93-01 “Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants,” dated May 1993 [2]. This approach to implementing the Maintenance Rule for EDGs is considered an “alternative approach” due to certain exceptions taken to the regulatory interpretation of industry guidelines, also discussed in this paper.