Accident management insights through the industry individual plant evaluation process

The paper presents a process for developing plant specific severe accident management insights through the use of a streamlined individual plant evaluation methodology (IPEM). The IPEM was developed as part of the Industry Degraded Core Rulemaking (IDCOR) Program. IDCOR performed an extensive technical evaluation of severe accidents, identified the significant issues and provided the technical basis for resolution of these issues with the Nuclear Regulatory Commission (NRC). In 1985, the NRC issued a Severe Accident Policy Statement that required individual plants to undergo a systematic evaluation to determine whether these plants have unique vulnerabilities or unusually poor containment performances. In response to this requirement, the U.S. utility industry through IDCOR undertook the development of a methodology designed to apply the severe accident insights learned from the evaluation of four reference plants and from previous risk assessment studies to the systematic evaluation of individual plants. The IDCOR IPEM, which consists of both a systems and a containment evaluation methodology, has undergone extensive review by the NRC and has been applied by eight utilities as part of a trial use and test application program. Several of the trial application plants also have had full scope probabilistic risk assessments (PRAs) performed. Comparison between the applications of the IPEM and the results from PRAs shows that the IPEM consistently provides comparable insights at less cost and in some cases had identified items not detected in the PRA. These IPE insights form a basis for individual plant accident management strategies and the IPEM can be a major element of an accident management program. These insights can also be used in such a program to identify, monitor and maintain existing good operational and maintenance practices. Aggressive application of IPEM insights could allow a utility to develop an accident management program defining possible accident management strategies, improved accident management organization and training for severe accidents. 3 refs, 3 figs