One person has been killed and four injured, one seriously, by an explosion on 12 September at the Marcoule nuclear waste treatment plant near Marseilles in southern France. The explosion hit the plant at 11.45 local time (09.45 GMT).

Although there were no radioactive leaks reported after the blast, caused by a fire near a furnace in a radioactive waste storage site, a security perimeter has been set up because of the risk of leakage.

But the French government and plant owner EDF quickly set out to play down fears of a spread of radioactive material. An EDF spokesman said: “This is an industrial accident, not a nuclear accident. The fire started by the explosion is under control.”

“Initial reports suggest there was an explosion in an oven used to melt metallic low- and very low-level radioactive waste,” the French Nuclear Safety Authority, ASN, said.

The blast hit the Centraco nuclear waste treatment centre, which is part of the Marcoule complex. Marcoule is a major site involved with the decommissioning of nuclear facilities. The plant produces MOX fuel, a product of the process whereby plutonium from nuclear weapons is recycled, but there are no reactors there. It was built in 1955 originally for plutonium production for nuclear weapons and is now used by French nuclear firm Areva for the clean-up and dismantling of nuclear installations and as a research centre of the Atomic Energy Commission (CEA). The Centraco treatment centre belongs to a subsidiary of national electricity provider EDF.

EDF’s share prices fell by more than 6% as news of the blast emerged.