STUK granted start-up permission for OL2 plant unit
The Radiation and Nuclear Safety Authority in Finland (STUK) has granted start-up permission for the Olkiluoto 2 plant unit (OL2) at the Olkiluoto nuclear power plant of Teollisuuden Voima (TVO). The plant unit was disconnected from the national grid due to an operational disturbance on Thursday 10 December at 12:22. The immediate actions required to prevent the recurrence of the event have been implemented.
Monday 14 December TVO submitted an application for start-up permission to STUK. The application provided a detailed clarification on the progression and the causes of the event, a comprehensive report of the actions to be carried out prior to start-up as well as a safety assessment. The actions and activities included, among others:
• Inspections of electrical motors, sensors, connectors, transmitters and limit switches.
• Inspections of insulation and penetrations.
• Inspection of the cleanliness of the water in the suppression pool.
• Operational tests of the valves on the containment.
• Testing the control rod maneuvering devices and the reactor trip function.
STUK reviewed the reports submitted by TVO and supervised the inspections, tests and maintenance activities conducted on the plant site. The inspections and clarifications did not bring up any obstacles to the start-up of the plant unit in terms of safety or the availability of systems or components. TVO will finalise the last required inspections, tests and maintenance activities before the start-up of the plant unit.
TVO has carried out the required actions to prevent similar events.
The disturbance caused no harm to people or the environment. STUK rated the event at level zero on the INES scale, i.e. the event did not affect nuclear safety.
The latest schedule estimates the reconnection of the plant unit to the national grid to take place during the end of the week. STUK will verify the readiness of the plant unit for start-up before the plant unit is connected back to the grid.
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