TWO workers have been hurt by a blast of high-temperature steam at the Fessenheim nuclear plant in Haut-Rhin, Alsace - but the prefecture has denied there was any chemical fire.
The plant, the oldest in France, has two 900MW reactors that were put into service in 1977.
A prefecture spokesman said that the event happened during maintenance just before 16.00 when a reservoir of hydrogen peroxide reacted with water and blasted out the high-temperature steam.
Two workers were scalded on the arms by the blast which set off fire alarms.
Around 50 firefighters were on the scene.
The incident could open up the nuclear power debate in France, where it supplies nearly 80% of the energy needed.
During the election campaign FranÃ§ois Hollande promised to close Fessenheim, but Nicolas Sarkozy told workers then "there's no question of closing this plant".