Areva, France’s nuclear engineering group, on Friday confirmed that the initial cost of building nuclear reactors is soaring, just as demand is rising for a more cost-effective source of power than oil and coal.

The group has taken its sixth provision in two years to cover cost overruns and delays to its new generation reactor in Finland, called OL3. Though Areva refused to quantify the provisions so far, senior management on Friday confirmed reports that the final price would be closer to €4.5bn ($6.6bn) instead of the initial €3bn estimate.