Plant Operation

TVO Brings Forward Olkiluoto Outages To Remove Damaged Fuel

By David Dalton
30 April 2019

TVO Brings Forward Olkiluoto Outages To Remove Damaged Fuel
The Olkiluoto nuclear power station in Finland.

30 Apr (NucNet): Finnish power company TVO has brought forward annual outages at the Olkiluoto nuclear power station by four days because of the need to remove damaged fuel from Olkiluoto-2.

TVO said in a statement that “some amount of radioactive substances” have been released from damaged fuel into reactor water, but there is no risk to the environment.

The annual outages will start on 1 May instead of 5 May. Plant shutdown procedures will begin on 1 May at 21:00 and Olkiluoto-2 will be disconnected from electricity production at 23:00.

According to the schedule, Olkiluoto-2’s annual outage will be completed on 26 May.

In addition to refuelling, work to be carried out at Olkiluoto-2 includes a pressure test of the primary circuit, renewal of the heat exchanger in the reactor-water purification system, the renewal of the low-voltage bushings in the containment and the renewal of the 400 kV switchgear.

Damaged fuel assemblies will be removed from the reactor and replaced with fresh fuel, TVO said.

The annual outage at Olkiluoto-1 is a refuelling outage. It will start on 2 June and is scheduled to be completed on 11 June.

TVO did not give any details about the damaged fuel, but slight damage to fuel is not uncommon in light-water reactors. The damage can consist of small fissures in the cladding.

In October 2017 TVO shut down Olkiluoto-1 after it found indications of potentially damaged fuel.

Olkiluoto-1 and -2 are both 890-MW boiling water reactors. They began commercial operation in 1979 and 1982 respectively and according to TVO produce 22% of Finland’s electricity.

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