In OL3, the chain of events affecting safety – “Not compromised”

“At the Olkiluoto 3 plant unit, a possible chain of events starting with a network failure and affecting safety was identified in the safety analyses. With immediate corrective measures, the continuation of production was ensured without interruption”, The Power of Industry tells.

According to TVO, a network failure could have led to the failure of certain equipment related to reactor cooling.

“Immediate corrective measures have been taken, electricity production has continued at the OL3 plant unit without production interruptions,” says TVO.

TVO has submitted a preliminary usage event report on the matter To the Radiation Protection Center.

According to STUK, it was a matter of deficiencies in the plans and instructions made in case of a disturbance in the electrical systems.

“The plant’s safety was not compromised,” says STUK.

An extraordinary event

The detected deficiencies could have compromised the reactor’s cooling in the unlikely event of electrical system failures.

TVO submitted its findings and repair plan to the Radiation Protection Center on Thursday, March 5 and Friday, March 6.

STUK also made its own assessment, according to which TVO’s assessments were correct and the proposed measures were sufficient.

The immediate measure was to update the instructions for the plant’s operators in case of a possible disruption.

Since the detected deficiency was related to safety functions, STUK assessed the incident as belonging to category 1 on the international nuclear power plant incident severity scale, i.e. it was an exceptional incident affecting safety.