The French Nuclear Safety Authority (ASN) has determined that Reactor 1 of the Cattenom nuclear power plant must be repaired before it can be reactivated.

The ASN specifically mentions two welds that must be repaired due to corrosion on the pipe network in a statement issued Thursday evening.

The French energy supplier EDF conducted inspections, which revealed cracks with maximum depths of 4.7 and 6.1 mm. The ASN reviewed the results of the check to determine if the reactor could be reactivated for an eight-month period.

The ASN states that "the strength of the pipes affected by these two indications is not assured, and the welds concerned must therefore be repaired before the reactor can be restarted." Other welds that have been less affected by corrosion can be maintained in their current state "for a limited period of time."

EDF has undertaken to replace all sections of the safety injection system piping that are susceptible to cracking during the next reactor shutdown, scheduled for 2023.