PARIS — One person was killed and four were injured Monday afternoon in an explosion at a nuclear waste treatment site in southern France, according to the French Nuclear Safety Authority.
The authority and local police officials said there had been no radiation leak. About five hours after the explosion, the authority announced that the episode was over. The site, about 20 miles from Avignon, has no nuclear reactors, the authority said. A spokesman for the French power utility Électricité de France, which owns the site, said, “It is an industrial accident, not a nuclear one.”
Olivier Isnard, an emergency manager at France’s Institute for Radioprotection and Nuclear Safety, said the explosion took place in the foundry of the waste processing plant, which was melting about four tons of used, mildly radioactive metal objects. The cause of the explosion was not yet known, he said, but he emphasized that the level of radiation — about 67,000 becquerels — contained in the molten metal was minor.
“This is very, very low — nothing close to the radioactivity you would find inside a nuclear power plant,” he said.
Even so, firefighters set up a security perimeter around the installation.
The spokesman for the utility said the foundry oven was used to destroy two types of low-level waste — “metallic waste, like tools and pumps,” and “burnable waste, like gloves or technicians’ overalls.”
He said the fire caused by the explosion had been controlled.
The French Interior Ministry said the workers were not contaminated. The Nuclear Safety Authority said one injured person was in serious condition.
The facility where the explosion took place is known as Centraco and is owned by Socodei, a subsidiary of EDF.
Mr. Isnard said that initial tests at the site showed no change to environmental radiation levels, and that the foundry building’s conditioning and ventilation systems continued to function normally. A crisis team and a group of specialized firefighters were dispatched to take air and soil samples, he said.
Nathalie Kosciusko-Morizet, a government minister responsible for energy and environmental issues, visited the site.
She characterized the event Monday as an “industrial accident at a nuclear site” which she conceded had “aroused emotion and vigilance.”
Cécile Duflot, a leader of the French Green Party, asked the government “for the greatest transparency, in real time, about the situation and the environmental and health consequences.”
France in recent months has reaffirmed its commitment to nuclear power — which provides 77 percent of the country’s energy needs — even as neighboring countries, including Germany and Switzerland, have shrunk from nuclear in the wake of the Fukushima accident in Japan in March.