Refuelling PSA for TVO I/II

The utility TVO is conducting a comprehensive PSA programme for its two 710 MWe BWRs. The programme was initiated by the utility in the year 1984, and the level 1 PSA was taken into living use in 1992 including internal transients, LOCAs and fires during power operation. In the year 1990 the utility decided to extend the PSA study by the analysis of refuelling, shut down and start up. One reason for the decision was the good operating experience of both units. They have continuously exceeded 90 per cent annual capacity factor due to short and effective refuelling outages and suffered only a few unplanned shut downs. The Shut-down event PRA (SePRA) required development and application of new methods because the human factors are the main contributor both to the initiating events and the loss of safety functions. The few studies published were used as a starting point for SePRA. 8 refs, 2 figs, 3 tabs