Reactor pressure vessel closure head installed at OL3

​The closure head of the reactor pressure vessel, equipped with control rod drive mechanisms and cabling for in-core instrumentation, was fit in place at the end of August. The head weighs ca. 170 tons and during power plant operation it is attached to the pressure vessel with 52 bolts. The reactor coolant system of a pressurised water reactor includes the pressure vessel, four reactor coolant pumps, a pressuriser and four steam generators.

The reactor internals were lowered into the pressure vessel at the same time with the closure head. All lifting and fitting operations were completed successfully.

The closure head lifting operation in Olkiluoto was the first ever such event on the plant site of a nuclear power plant of OL3 type, i.e. an EPR plant (European Pressurised water Reactor).

Fuel will not be loaded in the reactor until the commissioning tests have been completed and an operating licence has been granted to the plant.