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It evaluates the safety performance off NPPs using 2 areas, 4 categories and 15 indicators and provides the evaluation result in 4 colors for public understanding


Safety Performance Indicator(SPI)

SPI is a means to show the operational safety of a nuclear power plant and its radiological influence etc., and a trend analysis of safety performance can be performed.

Significance of SPI Evaluation

  • Confirmation of NPP safety, with quantitative operational performance.
  • Efficient regulation through trend analysis of indicators.
  • Enhancement of public confidence in the operational safety of NPPs.

Structure of SPI System

Grade of SPI

Excellent  Excellent : Safety margin is more than sufficient

Good  Good : Safety margin is sufficient

Normal  Normal : Safety margin is within expected norms

Warning  Warning : Safety margin is below norms while technically safe

Development of SPI

As the public's interest in nuclear safety is increasing, a useful measure to show and easily perceive how the NPPs are being safely operated needs to be developed. Accordingly the international nuclear organizations and the regulatory bodies such as IAEA, WANO, and USNRC began to develop the PI (performance indicator) system to oversee the safety performance of NPPs.


Domestically the safety performance indicator (SPI) system was introduced in 1995 and applied to the operating PWRs for the performance trend analysis using 10 performance indicators. This PI system was used to monitor the long-term safety status of the NPPs operation, to allocate regulatory resources and to facilitate international cooperation.


The SPI system was revised in the second quarter of 2005 and in the forth quarter of 2015. The current SPI system is composed of 2 safety areas, 5 categories, and 15 indicators. Each indicator is color coded to represent its safety performance grade. The four colors representing the grades are green, cyan, yellow, and orange, each of which stands for excellent, good, normal, and warning grade, respectively.