INES-event
INES 1

SIMULTANEOUS INOPERABILITY OF TWO HIGH-PRESSURE ECCS PUMPS

Unit 4 was operating at nominal power and one of the three safety systems was inoperable due to scheduled maintenance activities. This condition was in accordance with relating procedures of the Operating Technical Specifications.
On July 14, 1994 at 11:05 the personnel noticed that suction leg of a high pressure pump of another safety system is connected instead of the high concentration boric acid tank to the tank of low concentration boric acid. This is an anomaly as in this condition the pump can't fulfill its whole planned function and therefore it has to be considered inoperable. Based on the preliminary statements this condition had been existing since July 14, 1994, 01:19. Thus two high-pressure ECCS pumps were inoperable for almost 10 hours which is a violation of the Operating Technical Specifications.
The anomaly was eliminated after its detection immediately.

Location: PAKS-4
Event date: Thu, 14-07-1994
Nuclear event report
Legenda & explanation