Key Issues
New Performance Index Provides Closer Look At Nuclear Plant Safety Systems
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March 2006
Key Facts
March 2006
Key Facts
- The U.S. Nuclear Regulatory Commission provides oversight of nuclear power plant performance in three major areas: reactor safety, radiation safety and security. To assess plant performance, the NRC evaluates the results from 18 performance indicators for each nuclear power plant, in addition to the results from its baseline and supplemental inspection program. The agency posts these evaluations on its public Web site.
- Since its inception in 2000, the reactor oversight process has relied on safety system unavailability (SSU) performance indicator to assess safety system performance. The NRC and the industry recognized that the SSU indicator had significant shortcomings in that it did not adequately address safety system reliability—that is, how well systems will perform if needed.
- The NRC and the industry have developed and tested a substitute indicator that provides a more accurate assessment of these systems. The result is the mitigating system performance index (MSPI). The index uses existing equipment performance data industry baseline performance data, and safety-importance weighting factors derived from plant probabilistic safety assessments to evaluate plant equipment performance.
- The MSPI has numerous advantages over the previous method. It provides information on both the availability and reliability of safety systems. The data are readily accessible, making it easier and more efficient for the NRC to verify performance data during inspections. In addition, because it uses the latest probabilistic safety information, the MSPI will help the NRC focus its inspection resources on areas important to safety.
- The industry has developed guidance for plants to use in implementing the MSPI and has conducted industry training. The industry and the NRC have reviewed implementation documents to ensure the guidance is implemented properly at each nuclear plant.
