Olkiluoto 2 nuke plant remains closed after abnormal operation

A severe abnormal disturbance occurred at the Olkiluoto nuclear power plant Unit 2 on Thursday afternoon, which led to shut down of the reactor, said the Radiation and Nuclear Safety Authority (STUK).

The disturbance that took place at 12:22 PM was possibly caused by a fault in the water purification system for the reactor.

The situation, however, became stable and the unit achieved a safe state. There was no radioactive release to the environment.

There is no need for protective measures due to the situation. There is no danger outside the unit and no radioactive release is expected.

Iodine tablets shall not be taken, and there is no need for other actions such as staying inside. The radiation situation outside the unit is normal, said the STUK in a press release.

The abnormal operation occurrence was initiated when the radiation measurement instrumentation inside the unit alarmed for increased radiation levels. The higher levels were detected in spaces where the levels are high even during normal operation.

Consequently, there are no workers during operation. The personnel have not been exposed to radiation and there are no personnel injuries.

The containment building was isolated so that the safety of the plant and plant environment was ensured.

Both the power company and STUK started their emergency organisations and activities according to emergency preparation plans. There is no indication of fuel leakage and there are no more abnormal radiation levels at the unit.

“STUK started the emergency activities immediately in full force due to exceptionally high radiation levels inside the unit. There are about 80 persons following the situation, but we do not see acute threat,” said STUK Director General Petteri Tiippana.

The plant will be shut down to cold state so that the cause of the fault can be determined. The inspectors of the Radiation and Nuclear Safety Authority (STUK) monitor the situation on site.

“TVO must thoroughly investigate the day’s events, as the operator is responsible for the safety of the nuclear power plant. STUK will continue to monitor the situation. The plant will only be started up when safety has been ensured,” added Tiippana.