During preventive maintenance checks on the primary circuit of reactor number 1 of the Civaux Nuclear Power Plant (in the Vienne Department of France), scheduled as part of its ten-yearly in-service inspection, some defaults were detected close to the welds on the pipes of the safety injection system (SIS[1>) circuit. The French nuclear safety authority, Autorité de Sûreté Nucléaire (ASN) was informed of this detection.

Checks initiated on the same equipment of reactor number 2 of the Civaux Nuclear Power Plant revealed similar defects.
Today, a decision has been taken to replace the affected parts on the two Civaux reactors, the work being governed by a technical instruction prepared in cooperation with the ASN, which leads to extend the shutdown of the two reactors

The four reactors of the Chooz (in the Ardennes Department) and Civaux nuclear power plants use the same technology and form the N4 reactor series of the French nuclear fleet. As a responsible nuclear operator, and as a precautionary measure, EDF has therefore taken the decision to shut down the two reactors of the Chooz Nuclear Power Plant so that, proceeding proactively, it can carry out the same checks on the SIS circuit which can only be possible as the reactors are offline. The Chooz number 2 reactor will be shut down on Thursday 16 December and the Chooz number 1 reactor will be shut down on Saturday 18 December.

These checks, together with the deployment of the technical solution, are being implemented in close cooperation with the ASN.

The extension of the Civaux’s reactors outage and Chooz’s reactors shut down will result in a loss of about 1 TWh by the end of 2021 which  leads EDF to revise its EBITDA estimate, based on current market prices, to a range of 17.5 to 18 billion euros, against the previous target of an EBITDA of more than 17.7 billion euros. EDF confirms its target NFD/EBITDA of less than 2.8x.


[1> The safety injection system (SIS) is a back-up circuit that ensures the cooling of the reactor in the event of an accident. It allows borated water to be injected into the reactor core in order to stop the nuclear reaction and to maintain the volume of water in the primary circuit in the event of a loss of primary coolant accident.

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