Failure of safety system train during routine testing
Thursday, October 1, 1998
On July 13, 1998 unit 2 was under 160 MW power. According to the approved programme testing of emergency feed water pumps (EFP) was performed. The test showed EFP-B non-operability. By switching on the EFP-A it switched on, however in 3 minutes it was switched off by the pump protection. Operating personnel did not decrease the reactor power after the testing, as it should be made according to the OL&C. The EFP-A operability was restored in 3 hours 10 min. The EFP-B operability was restored in 6 hours 20 min. A repeated testing was performed without notes. The event caused neither on-site nor off-site radiation impact. Justification of the rating: Basic rating: Defense in depth criteria: level 1 according to the Table 1, part III of the INES User's Manual. Upgrading: safety culture. Additional upgrading factor was taken into account according to chapter III-5.3 of the INES manual, namely, the violation of OL&C without justification. The final rating was selected as level 2.