French nuclear firm Areva now says a leak of waste containing non-enriched uranium from a site in southern France was smaller than initially thought.
30 thousand litres of solution containing 12g of non-enriched uranium per litre spilled from an overflow at the Tricastin plant 40 kilometres north of Avignon.
But the company says only half that amount found its way into two nearby rivers.
“It was not 30 cubic metres, as we originally thought. That was how much leaked from the tank, but some of it was caught in time, so only around half that amount spilled onto the ground.” said a spokesman.
The run-off is thought to have gone into the Gaffiere and Lauzon rivers, which feed into the Rhone.
The authorities have banned all fishing, sailing and swimming in the affected area as a precaution and say the risk to health is slight.
But environmental campaigners believe the authorities are underplaying the risks posed by the leak and have called for an inquiry.
The nuclear safety authority says it will carry out an inspection tomorrow to determine the cause of the accident.
The incident comes at a time when much of Europe is re-embracing nuclear power as a cheaper and cleaner way of generating energy.
France is one of the world’s most nuclear-dependent countries, with 80% of its electricity coming from nuclear plants.