Finland’s Radiation and Nuclear Safety Authority (STUK) has said that the preliminary safety assessment it conducted in 2009 for the Olkiluoto 4 project is still valid.

The regulator was asked to review the assessment by the Ministry of Employment and the Economy after TVO requested a five-year extension to the application period for the licence to construct a nuclear power plant. TVO was due to apply for a construction licence for the OL4 project by June 2015.

STUK said that from the perspective of nuclear safety, there is no impediment for granting an extension for the application period.

"It is STUK’s view that this additional time can be used beneficially to develop the safety aspects of the selected power plant type, to carry out further investigations on the plant site and to improve TVO’s expertise and management system," the regulator said in a statement.

It also said that the amended schedule for Olkiluoto 4 would also not affect the preliminary safety assessment on the repository for the final disposal of reactor waste.

TVO applied to the Finnish government for an extension in May.