INES-event
INES 1

LEAKING ISOLATION VALVES IN THE EMERGENCY CORE COOLING SYSTEM

A leakage was observed during periodical testing of the core spray system at a valve aligned to the suction side of one of the core spray pumps, in the Emergency Core Cooling System. To repair the valve, the reactor was shut down. Inspection of the system revealed another leaking valve, an isolation valve, at the suction side of the same pump. During inspection of the other circuit of the core spray system it was detected that the corresponding valves were leaking there too. The reason of the leaks at these motor operated valves was the erroneous adjstument of the motr operated mechanisms to the respective valve stems during installation. INES level 1.
Table 1, severity classification criteria for degradation of defence in depth without an initiator.
Initiator probability: low/unlikely, safety function availability: adequate.

Location: BARSEBECK-2
Event date: Wed, 31-08-1994
Nuclear event report
Legenda & explanation