One person was killed and four injured in an explosion at the French nuclear site of Marcoule on Monday.
There have been no radiation leaks from the plant, which is used to help decommission other facilities, the French Nuclear Safety Authority said.
There are no nuclear reactors at the plan, which is in south-east France, near the Mediterranean Sea.
"According to initial information, the explosion happened in an oven used to melt radioactive metallic waste of little and very little radioactivity," the Nuclear Safety Authority said in a statement.
A source within the International Atomic Energy Agency (IAEA) told RIA Novosti that there is little chance of a radiation leak.
