There was no risk of a radioactive leak after the blast, caused by a fire near a furnace in the Centraco radioactive waste storage site, said officials according to various media reports.

The plant’s owner, national electricity provider EDF, said it had been “an industrial accident, not a nuclear accident.”

“For the time being nothing has made it outside,” said one spokesman for France’s Atomic Energy Commission who spoke anonymously to the BBC.

The Centraco treatment centre, which has been operational since February of 1999,  belongs to a subsidiary of EDF. It produces MOX fuel, which recycles plutonium from nuclear weapons.

“[Marcoule] is French version of Sellafield. It is difficult to evaluate right now how serious the situation is based on the information we have at the moment. But it can develop further,” said Bellona nuclear physicist Nils Bøhmer.

The local Midi Libre newspaper, on its web site, said an oven exploded at the plant, killing one person and seriously injuring another. No radiation leak was reported, the report said, adding that no quarantine or evacuation orders were issued for neighboring towns.

A security perimeter has been set up because of the risk of leakage. The explosion hit the site at 11:45 local time.

The EDF spokesman said the furnace affected had been burning contaminated waste, including fuels, tools and clothing, which had been used in nuclear energy production.

“The fire caused by the explosion was under control,” he told the BBC.

The International Atomic Energy Agency (IAEA) said it was in touch with the French authorities to learn more about the nature of the explosion.

IAEA Director General Yukiya Amano said the organisation’s incident centre had been “immediately activated,” Reuters reports.

A statement issued by the Nuclear Safety Authority also said there have been no radiation leaks outside of the plant. Staff at the plant reacted to the accident according to planned procedures, it said.

France’s Nuclear Safety Authority, however, is not noted for its transparency.

Operational since 1956, the Marcoule plant is a major site involved with the decommissioning of nuclear facilities, and operates a pressurised water reactor used to produce tritium.

The site is has also been used since 1995 by French nuclear giant Areva to produce MOX fuel at the site’s MELOX factory, which recycles plutonium from nuclear weapons. Part of the process involves firing superheated plutonium and uranium pellets in an oven.

The Marcoule plant is located in the Gard department in Languedoc-Roussillon region, near France’s Mediterranean coast.

Marcoule: Sellafield’s French brother

Its first major role upon opening was weapons production as France sought a place among nuclear nations. Its reactors generated the first plutonium for France’s first nuclear weapons test in 1960.

Its reactor producing tritium as fuel for hydrogen as well as other weapons related reactors sprang up as the arms race gained international traction.

The site also houses an experimental Phenix fast-breeder reactor which since 1995 has combine fissile uranium and plutonium into mixed oxide or MOX fuel that can be used in civilian nuclear power stations.

Now the Marcoule site bears analogy to Britain’s Sellafield. Built to meet military demand without much thought as to how the waste would be cleaned up, it is now primarily concerned with dealing with France’s legacy of nuclear waste.

France depends on nuclear power for 75 percent of its power needs.

All the country’s 58 nuclear reactors have been put through stress tests in recent months, following the disaster at Japan’s Fukushima Daiichi nuclear power plant which was hit by an earthquake and tsunami.

But France is also one of the largest European nations not to reconsider the use of nuclear power as the crisis in Japan grinds on.

Germany has already voted to close down all of its nuclear reactors by 2022, and eight of its oldest were taken off the grid immediately following the March 11 earthquake in Japan. Italy turned out for a massively popular referendum over the summer to halt any plans of building any nuclear power plants.

Switzerland, likewise, is considering plants to shut down all five of its reactors by the year 2035.