EDF revises schedule, costs of Flamanville EPR

Wednesday, 25 July 2018

In a PWR, steam generators transfer reactor core heat from the primary coolant loop into a secondary loop where it can be used to generate electricity. The secondary loop is a closed system in which steam produced in the steam generator is conducted towards the turbine. Once condensed, the water is returned to the steam generator.

A quality deviation in the welding of the main secondary system of the Flamanville EPR in Normandy, northern France, was detected on 21 March during the initial comprehensive inspection, a regulatory requirement prior to the reactor starting up. This inspection includes an examination of the welds in the primary and secondary systems, and allows an initial reference state of the plant to be established before it begins operating.

Following the detection of further deviations, EDF decided to carry out additional checks on the 150 welds in question in order to identify exactly which ones are subject to quality deviations.

At the end of May, EDF said the impact on the schedule and, if necessary, the cost of the Flamanville 3 project would be announced once it had completed its discussions with the French nuclear safety regulator, the Autorité de Sûreté Nucléaire (ASN). However, at that time it warned that the start-up of the reactor could possibly be delayed by "several months".

EDF announced today that it has now inspected 148 of the 150 welds in the main secondary system of the Flamanville EPR and expects to inspect the two remaining welds by the end of this month.

The utility said that of the 148 inspected welds, 33 have quality deficiencies and will be repaired. A further 20 welds will be redone, even though they do not have any defects, as they "do not comply with the 'high quality' requirements defined by EDF during the EPR design phase", it said. For ten other welds, EDF has submitted a proposal to the ASN detailing a specific justification method to confirm the high level of safety at the plant throughout its operating life. The ASN will conduct an in-depth examination of this method. The remaining 85 welds are compliant.

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

In order to take account of the continuing weld inspections and the repairs of those not meeting requirements, EDF has revised its start-up scheduled for the Flamanville EPR. Hot functional tests - which involve checking the equipment under similar temperature and pressure conditions to those under which it will operate - had been due to start this month but will now begin before the end this year. The loading of fuel into the unit's core is now expected in late-2019 instead of late-2018. The company also raised the target construction costs for the plant from EUR10.5 billion to EUR10.9 billion (at the 2015 rate, excluding interim interest).

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

On 29 June, Taishan 1 became the world's first EPR to achieve grid connection and power generation. It is expected to enter commercial operation later this year. Taishan 2 - which is in the equipment installation phase - is scheduled to begin operating next year. Olkiluoto 3, the first-of-a-kind EPR, has completed hot functional tests and is preparing to load fuel. Two further EPRs are planned for the Hinkley Point C plant in Somerset, England.