On 21 June 2023, Teollisuuden Voima (TVO) informed the Radiation and Nuclear Safety Authority (STUK) that on Tuesday, 20 June 2023, unit 3 (OL3) of the Olkiluoto nuclear power plant deviated from the minimum number of control room personnel for slightly less than two hours. The minimum number of control room personnel has been considered in the design of the plant and is specified in TVO's administrative procedures and in the Operational Limits and Conditions (OLC) of the unit.
The event had no direct impact on nuclear safety. However, the operational capacity of the facility's control room personnel had decreased, and, in the event of a potential incident or accident, this could have affected the performance of the control room measures and thus the safety of the plant.
TVO submitted a report on the event to STUK on 3 August. Since the event, TVO has taken corrective measures, including in its administrative rules, to ensure that a similar event does not occur again. STUK will now review the event report submitted by TVO and take a decision on it.
Since the event involved a conscious deviation from the administrative requirements of the OLC, STUK classifies the event as category 1 on the International Nuclear and Radiological Event Scale (INES). According to the INES, the event was classified as an Anomaly.
For more information on the INES scale, see stuk.fi:
International Nuclear and Radiological Event Scale INES
Further information
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