EDF said Wednesday it has informed French nuclear regulator ASN that 20 of its operated nuclear reactors could be at risk of flooding due to certain weakness in their pumping stations' pipes.
As part of its equipment maintenance program, EDF carried out inspections on all the pipes in the pumping stations, which supply water to the reactors' cooling source, Kallanish Energy learns.
“Extensive investigations have revealed thinning of the metal in certain sections of piping, thus making it impossible to guarantee their seismic resistance in the event of a ‘reference’ earthquake,” EDF said, in a statement.
“This could potentially cause flooding in the pump houses of 20 reactor units, thereby resulting in the functional loss of both reactor cooling water systems,” it added.
Safety study cases for nuclear power plants are based on two reference earthquake levels: the maximum historically probable earthquake (MHPE), which is superior to all earthquakes that have occurred in the vicinity of the power plant for 1,000 years; and the safe shutdown earthquake, a hypothetical earthquake releasing energy five times greater than a MHPE.
EDF said the faults had no impact on the environment or on those working on the reactors. It reinforced the pipes in nine units, while it’s continuing additional pipe reinforcement in another five reactors, before they are restarted.
Another 28 units have been tested and no risk of flooding of pumping stations was found.