Finland's Radiation and Nuclear Safety Authority (STUK) said Tuesday it had ordered a halt on welding on the primary cooling circuit at the Olkiluoto nuclear power station building site.

The watchdog added that French nuclear power group Areva, the supplier of the power station, had discovered small cracks on pipes forming part of the circuit.

STUK added that the cracks were microscopic and could be mended through sanding and rewelding.

But STUK said Areva and Teollisuuden Voima, the eventual operator of the power station, would have to submit a report on the faults before the welding could resume. The Olkiluoto 3 project is running years behind schedule.

STT