Aggregation of safety performance indicators to higher-level indicators

In the hierarchical structure of IAEA safety performance indicators (SPIs) the top level is operational safety performance. Safety performance cannot be measured directly. Aggregation is a process by which the indices of the lower-level indicators are combined to get the numerical index for the next higher-level indicator. Hence, with the help of aggregation, the numerical index can be obtained for safety performance of a nuclear power plant. Karachi Nuclear Power Complex (KNPC) worked, under the auspices of IAEA, on developing guidelines for establishing goals and thresholds, aggregation to higher-level indicators and trend indices of SPIs. This paper presents the work done by KNPC on aggregation to higher-level indicators.