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
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