Finland activates its new Olkiluoto 3 nuclear reactor

OSLO, Dec 21 (Reuters) - Finland's much-delayed Olkiluoto 3 nuclear reactor has started up its critical functions, marking the first commission of a new nuclear plant in the country in over 40 years, operator Teollisuuden Voima (TVO) said on Tuesday.

The much-delayed reactor is not yet connected to the Finnish power grid however, with electricity production set to start at 25% or roughly 0.3-0.4 GW capacity from Jan. 22, TVO said in an updated statement late on Tuesday.

Plagued by technological problems that became the subject of a lawsuit, the 1.6 GW plant had originally been due to link up to the grid in 2009.

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The reactor started up at 0222 GMT on Tuesday according to TVO, which is owned by Finnish utility Fortum (FORTUM.HE) and a consortium of smaller energy and forestry companies.

To launch the reactor, so-called primary neutron sources are needed, which have been placed into three fuel assemblies in the reactor. These sources release neutrons, which start the splitting of atomic nuclei and creating the chain reaction that keeps the nuclear reactor running, TVO said.

Nuclear Safety Authority STUK granted TVO permission for making the reactor critical and conducting low power tests last week. read more

Regular electricity production is scheduled to start on June 6, according to TVO.

Once fully operational, Olkiluoto 3 will meet 14% of Finland's electricity demand, TVO has said.

There are already four other reactors in Finland.

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Reporting by Nora Buli, editing by Terje Solsvik and David Evans

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