Categorization of LOCA accidents in WWER-440 V213 NPP according to minimal safety system requirements

The study is devoted to identification of minimal safety system requirements and grouping LOCA initiators. Six LOCA categories is considered according to system success criteria - each LOCA category was defined to have the same system configuration logic and the same system capabilities. Certain number of cases were selected in order to investigate timing of accident progression and to estimate appropriate time margins for operator actions. Computer analyses performed with RELAP5/MOD3.0 are limited to LOCA initiating events, excluding LOCAs within the steam generator. Calculations were performed using the input data for WWER-440/V213 unit of BOHUNICE NPP prepared within the framework of IAEA Regional Program RER/9/004. The calculations provide some new evidence for reassessing the categorization of LOCA and related success criteria. Results of calculations are summarized in tables. (author)