Safety Performance Indicator(SPI)
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
|Area||Category||Specific Performance Indicator||Remark|
|Reactor Safety||Operational Safety||Unplanned Reactor Scram||URS|
|Unplanned Power Reduction||UPR|
|Unplanned Reactor Scram with Complications||USwC|
|Safety System||SI System Unavailability||SI|
|EDG System Unavailability||EDG|
|AFW System Unavailability||AFWS|
|RHR System Unavailability||RHR|
|CW System Unavailability||CW|
|Safety System Functional Failures||SSFF|
|Multiple Barrier||Fuel Reliability||FR|
|Reactor Coolant Leakage||RCL|
|Radiation Safety||On-site Rad. Safety||Radiation Collective Dose||RCD|
|Off-site Rad. Safety||Public Dose/Environmental Radiation||PD/ER|
Grade of SPI
Excellent : Safety margin is more than sufficient
Good : Safety margin is sufficient
Normal : Safety margin is within expected norms
Warning : Safety margin is below norms while technically safe
Development of SPI
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.