OL3 pre-operational testing consists of planned tests

At the pre-operational testing phase of a nuclear power plant, the plant unit and its safety systems are tested to verify that the plant operations comply with design. The pre-operational tests also comprise planned reactor trips. The production forecast for the pre-operational testing phase can be followed online at www.tvo.fi/ol3forecast.

Occasionally also unplanned reactor trips occur during pre-operational testing. Such an occurrence took place last Friday, 14 January 2022, in connection with the commissioning tests of steam generator level control. The reactor trip occurred when the level exceeded the reactor trip limit in one steam generator during the test.

- The plant remained in a safe state the whole time. We look at events that occur during the pre-operational tests as if the plant unit was already in electricity production. We carefully investigate the causes of the events and implement the required corrective actions before moving on to the next pre-operational testing steps. This approach also secures the trouble-free operation of the plant unit in the future, explains Marjo Mustonen, Senior Vice President, Electricity Production.

*The causes of the reactor trip have been identified and the required actions were taken before the plant unit was restarted. The production forecast for the pre-operational testing phase can be followed online at www.tvo.fi/ol3forecast.

‍*Updated 21.1.2022