2.3.2.3 Probabilistic safety assessment

Level 1 PSA for power operation

Level 1 PSA model for unit 1 was developed to analyze risk due to initiating events and to determine prevailing sequences of accidents of core damage. The model was developed in two modifications corresponding to two different reference states of the power plant: the first modification was based on the technical condition of NPP Mochovce unit 1 at the moment of start-up. This study confirmed that the requirements of INSAG 3 including core damage frequency was met. The second study has been prepared in accordance with the technical status of NPP Mochovce unit 1 after the full implementation of the safety improvement program and was finished in December 2000. The results confirmed considerable decreasing of CDF, but Mochovce NPP decide not to publish final figures before their evaluation by IAEA experts, scheduled in November 2001.

The probabilistic safety assessment of Mochovce NPP continue by SPSA study in the same extent as level 1 PSA, including specific SPSA study objectives and application.

SPSA model is foreseen to be developed so as to enable full uses of the model in the future for the following purposes: living PSA, real-time risk monitoring (RISKMONITOR), L&C optimization , level 2 PSA, optimization of the maintenance and testing strategy.

The project SPSA started in January 2001 and the planned completion date of is July 2001.

After that will continue the probabilistic safety assessment of Mochovce NPP with PSA level 2 performance. For that purpose, asked the plant through National Regulatory Authority of the Slovak Republic (ÚJD) the European Commission to confirm a new PHARE programme, which is preliminary considered to start in second half of year 2002.

Beside that, the implementation of the RISKMONITOR, as a tool for operational risk evaluation, is scheduled to be applied after the completion of the SPSA model