INES-event
INES 1

ONE CLOSED VALVE IN THE CONTAINMENT PRESSURE RELIEF LINE TO THE ATMOSPHERE AND TWO CLOSED VALVES IN THE VENTING LINE TO THE EMERGENCY FILTER

During a routine surveillance of the position indicating instruments in the control room, it was noticed that a valve in the contaiment pressure relief line to the atmosphere (system 361) and two valves in the venting line to the emergency filter (system 362) were closed. The valves were closed in connection with the annual testing after the refuelling outage. The testing procedures included the reopening of the valves. However, the valves were not restored to their correct (open) position, inspite that each step in the testing procedure was signed by the operator.
Instructions for testing during the outage are improved.
Justification of rating:
Level 1, anomaly beyond the authorized operating regime. Procedure based on initiators and safety function operability: Reactivity Control, cooling of radioactive materials, confinement of radioactive materials: Major LOCA up to an including the largest justfied pipe rupture in the reactor coolant boundary. Availability, within OL&C. Initiator did not occur.
Additional factors for uprating: Procedure inadequacies. Level 1

Location: FORSMARK-2
Event date: Sat, 15-07-1995
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