French utility EDF has announced the revised schedule of its pressurised water reactor (PWR) Flamanville EPR, following the discovery of quality deficiencies in several of the reactor’s welds.

Fuel loading for the 1,650MWe PWR was originally intended to take place in the fourth quarter of this year, while the cost was first predicted to be €10.5bn. Now, fuel loading has been pushed back to the fourth quarter of 2019, with the cost rising to €10.9bn.

Testing the equipment under temperatures and pressure conditions similar to those under which it will operate — known as hot functional tests—were due to start this month, but are now expected before the end of this year.

The altered schedule and cost come from a weld quality deviation in Flamanville’s secondary system. This was detected on 21 March during an initial comprehensive inspection, a check required before the reactor can commence operation.

Following this discovery, further deviations were detected, and EDF announced its decision to carry out further checks on 150 site welds to identify the ones subject to quality deviations.

Delays were anticipated from this point, with EDF saying at the end of May that it would announce the impact on cost and schedule following a discussion with French nuclear safety regulator, the Autorité de Sûreté Nucléaire (ASN).

As of 25 July, EDF had inspected 148 of the 150 welds in Flamanville’s secondary system and the inspection of the two remaining welds is expected to be complete by the end of the month.

According to the EDF, 33 of the 148 inspected welds were found to have quality deficiencies and will need to be repaired. An additional 20 welds were found to be non-compliant with “the ‘high-quality’ requirements defined by EDF during the EPR design phase” and will also need to be redone.

For another ten welds, the company has also submitted a proposal to the ASN with a specific justification method confirming the high safety level of the plant throughout its operating life. The ASN is to conduct an investigation into the efficacy of this method.

The remaining 85 welds were found to be compliant.

ASN has requested that EDF ‘in particular, implement an organisation and supervision to allow avoiding the repetition of the observed discrepancies’, adding that the utility will have to demonstrate that these welding operations make it possible to meet the requirements of the ‘rupture exclusion reference system’.

Construction of Flamanville began in December 2007, with commercial operation originally expected in 2013.