Finland’s Radiation and Nuclear Safety Authority (Stuk) has approved a report confirming that the reactor pressure vessel (RPV) steel of the European pressurised water reactor (EPR) under construction at unit 3 of the Olkiluoto nuclear plant "fulfils all quality requirements".

Stuk requested the report from Finnish utility Teollisuuden Voima Oyj (TVO), after anomalies were found in the composition of the steel in certain parts of the RPV head of the EPR under construction at unit 3 of France’s Flamanville nuclear plant. TVO submitted the report in June in cooperation with France’s Areva group, and further information was submitted by TVO in October.

TVO had said previously that the steel forgings of the Olkiluoto 3 RPV were manufactured in Japan "and no issues regarding material properties were found". RPV forgings for Flamanville 3, however, were made in France using a different manufacturing process. In April, Areva and EDF told the French nuclear safety authority (ASN) that additional tests were under way on the RPV head for Flamanville 3 after tests on a similar RPV head had revealed an area with high carbon concentration. ASN said later that tests had indicated "deficient manufacturing quality control, with an impact on the mechanical properties of the materials".

Areva announced later that independent experts had been called in to conduct an external review of its Creusot Forge plant in France, which manufactured the RPV upper and bottom heads for Flamanville 3.

The Areva-Siemens consortium, which is building Olkiluoto 3 for TVO, said last year that construction is set to be completed by mid-2016. System commissioning is expected to begin in the spring of 2016 with regular electricity generation starting in "more than three years", operator said. TVO said the estimated schedule came from plant supplier Areva-Siemens and "the next steps towards commissioning are now more accurate". TVO said it expects to apply for an operating licence for the plant in spring 2016.

Olkiluoto 3 has been under construction since 2005 and has seen several revisions to its startup date, which is now expected by 2018, nine years later than originally scheduled.