The seawater intake structures of the Olkiluoto 3 nuclear power plant in Finland have been opened, and the cooling water pumping station filled.

The work, AREVA said, is an important pre-requisite for the upcoming commissioning tests to be performed on the service water and cooling water systems of both the nuclear and conventional islands of the plant.

Once the leak tightness of the structures was checked and confirmed, the filling operation was successfully completed on 1 August by reaching equilibrium with sea level after a total filling duration of 7.5 hours.

The pumping station now contains 30.000 m³ of seawater safely isolated from the rest of the plant unit by concrete walls and physical blockings. The water will later supply the plant unit’s cooling systems.

During plant operation, around 53 cubic metres of seawater per second flows through the circulating water tunnel, utility TVO said.

According to a recent estimate in July, OL3 is not expected to be ready for commercial operation until after 2014.