EDF also decided to shut down Civaux NPP reactor 2 so that these inspections of the areas could be carried out ahead of schedule, as the previous inspections dated from 2012. The preliminary results of these inspections confirmed the presence of indications similar to those of reactor 1.
On 15 December 2021, EDF informed ASN that the initial metallurgical analyses conducted on the parts of the pipes removed from Civaux NPP reactor 1 revealed the presence of cracking resulting from a stress corrosion phenomenon. EDF is continuing its investigations in order to characterise the factors that caused this phenomenon and identify the areas potentially concerned.
Given the unexpected origin of the cracks detected, EDF decided to shut down reactors of similar design, as rapidly as possible. The B1 and B2 reactors of the Chooz NPP will therefore be shut down shortly for checks in addition to those carried out in 2019 and 2020 during their ten-yearly outage inspection.
ASN considers that given EDF’s prime responsibility for safety, its decision is an appropriate one for the situation.
With the technical support of IRSN, ASN is closely following the investigations being carried out by EDF, along with the resulting conclusions, notably with regard to in-service monitoring of this equipment. ASN authorises repair work on the equipment concerned and will issue a decision with regard to its return to service.
 An indication is a signal (typically an echo for ultrasound inspections) revealing the possible presence of a defect in the material being inspected.
 In the event of an accident causing a major break in the reactor’s primary system, the safety injection system (RIS) enables pressurised borated water to be introduced into it in order to stifle the nuclear reaction and cool the core.
Date of last update : 21/12/2021