EDF has detected quality deviations on certain welds of the main secondary system of the Flamanville EPR and has begun additional controls

As from 21 March 2018, EDF detected quality deviations on the welding of the pipes of the main secondary system⁽¹⁾ of the Flamanville EPR, during the initial comprehensive inspection – a regulatory requirement prior to the plant startup. The initial comprehensive inspection consists, in particular, in the examination of the welds of the primary and secondary systems, and allows an initial reference state of the plant to be established before its entry into operation.

In accordance with industrial procedures, the welds had been controled by the consortium of contractors in charge of manufacturing the system. Each weld had been declared compliant as it was realized.

Following the detection of quality deviations, EDF decided to carry out additional controls on the 150 welds in question on the main secondary system, in order to identify exactly which ones are subject to quality deviations. EDF has also ordered a report into the causes and nature of these deviations, in order to define the necessary corrective actions and the industrial methods to be proposed to the Autorité de Sûreté Nucléaire (ASN) so as to guarantee the expected safety requirements. The full set of checks and the report will be completed by the end of May.

On 10 April 2018, EDF notified the ASN of a significant event relating to the detection of deviations in the performance checks of these welds. Part of the main secondary system⁽²⁾ is already subject to a deviation with respect to the correct application of “high-quality” requirements, which was notified to the ASN on 22 February of this year⁽³⁾.

Following the current checks and the licencing process by the ASN, EDF will be able to specify whether the project requires an adjustment to its timetable and its costs. The loading of the nuclear fuel is currently due to take place at the end of the 4th quarter of 2018, while construction costs target of the project is EUR 10.5 billion⁽⁴⁾ excluding interim interest.

EDF’s teams and their industrial partners are fully mobilized and are pursuing the other assembly operations and tests at the Flamanville EPR, in particular the global checks. On 3 April of this year, the reactor building underwent pressure tests, a process known as the “container test”, which were completed satisfactorily and thus allowed the validation of the building’s design and resistance.

⁽¹⁾ A closed system in which the steam produced in the steam generator is conducted towards the turbine. Once condensed, the water is brought back to the steam generator.
⁽²⁾ The part of the main secondary system which conducts the steam from the steam generator towards the turbine.
⁽³⁾ Cf. article of 22 February 2018 on the Flamanville 3 EPR website.
⁽⁴⁾ In Euros of 2015, excluding interim interests.