Olkiluoto 3 EPR project reaches cold functional test stage


The first significant milestone of 2017 has been reached at the Olkiluoto 3 project with the start of the cold functional tests. The main purpose of the tests is to verify the leak-tightness of the primary circuit.
The cold functional testing stage will take about four weeks, and dozens of tests are to be carried out at different pressure levels. Main coolant pumps will be started for the first time. The pressure is increased gradually in the reactor coolant system to a maximum value significantly exceeding the normal operating pressure.

− This is an important step in plant commissioning. The hot functional tests scheduled for autumn are the next major milestone. Once this stage has been successfully completed, OL3 will fulfil the preconditions for the granting of the operating licence in early 2018. There are still several important milestones to be met before the start of the regular electricity production at the end of 2018, explains Mr. Jouni Silvennoinen, OL3 Project Director.

For more information, please contact:
Jouni Silvennoinen, OL3 Project Director, tel. +358 2 8381 4100.

*The primary circuit refers to the circulation of water between the reactor pressure vessel and the steam generators. The temperature of the water is increased to 328 degrees in the reactor pressure vessel, and the water is then lead in the reactor coolant piping to the steam generators, where heat is transferred from the water to the secondary circuit. The temperature of the water decreases to slightly less than 300 degrees, and the water returns to the reactor. A high pressure is maintained in the primary circuit to prevent the boiling of the water.