A Potential Safety Related Event Sequence Identified at Olkiluoto 3
A potential sequence of events affecting safety, beginning with a grid disturbance, was identified in the safety analyses of the Olkiluoto 3 plant unit. Immediate corrective actions were taken to ensure the continuation of electricity production without interruption.
A network disturbance could have led to the inoperability of certain equipment related to reactor cooling. Immediate corrective measures have been implemented, and electricity production at the OL3 plant unit has continued without interruption.
TVO has submitted a preliminary operational event report regarding the matter to the Radiation and Nuclear Safety Authority (STUK). TVO has initially assessed the severity of the event as level 1* on the international INES scale. STUK will confirm the final INES rating in connection with its review of the special report.
* The severity level of incidents at nuclear facilities is classified according to the international rating system. The INES scale has seven different severity levels, of which levels 4-7 are classified as accidents, levels 1-3 as safety-significant events, and level 0 as an exceptional event with no safety significance.
Johanna Aho, Head of communication, tel. + 358 40 729 0822
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