A 2014 incident in France's oldest nuclear plant, located near the German and Swiss borders, was more serious than previously reported, German media claimed today.
Flooding at the Fessenheim plant disabled electrical control systems and forced operators to launch an emergency reactor shut-down, reported public broadcaster WDR and Sueddeutsche Zeitung daily.
Operators decided to insert boron into the reactor cooling system, a procedure the report likened to "pulling the emergency brake", and which a nuclear safety expert said was a unique event in Western Europe so far.
The joint news report said that operators temporarily lost full control over the plant's reactor 1 in the April 9, 2014 incident after water had incapacitated one of two parallel reactor security systems.
The official reports by French nuclear safety agency ASN had not mentioned the use of boron, the media report said.
"I am not aware of any other case where a power reactor here in Western Europe suffered an incident in which it had to be shut down with the use of boron," nuclear safety expert Manfred Mertins was quoted saying.
Fessenheim houses two 900 megawatt reactors and has been running since 1977, making its France's oldest operating plant. Due to its age activists have long called for it to be permanently closed.
France, the world's most nuclear-dependent country, has been a leading proponent of atomic energy.
It has nevertheless promised to cut reliance on nuclear energy from more than 75 percent to 50 percent by shutting 24 reactors by 2025, while stepping up reliance on renewable energy.
President Francois Hollande has pledged to close the Fessenheim plant by the end of his five-year term in 2017.
