French nuclear regulator Autorité de Sûreté Nucléaire (ASN) said an expert group has recommended that Areva's proposed methodology to demonstrate the strength of the reactor pressure vessel (RPV) of the EPR, under construction at unit 3 of the Flamanville NPP, is "acceptable".
The group presented its recommendations at a meeting with ASN, attended by representatives of the Haut comité pour la transparence et l'information sur la sécurité nucléaire and the Association Nationale des Comités et Commissions Locales d'Information, as well as foreign safety authorities involved in construction of the unit, as observers.
EDF is architect engineer for Flamanville 3, Areva is contributing the nuclear steam supply system and Bouygues Construction leads the civil engineering consortium. In April, ASN, Areva and EDF revealed that chemical tests had shown higher than average carbon content in the Flamanville RPV, indicating a manufacturing flaw which could potentially affect the vessel's ability to withstand cracks such as an unexpected rupture of the upper or bottom heads of the RPV.
In May, Areva sent ASN a proposed methodology, including possible additional tests, to justify the acceptability of the mechanical properties of the RPV. The experts group said Areva's proposed methodology was acceptable subject to four recommendations relating to additional tests that could be done. Areva has also said independent experts would carry out an external review of Areva's Creusot Forge plant in France, which manufactured the RPV top and bottom heads for Flamanville 3. This review, by British-French company Lloyd's Register Apave Ltd, would focus on forging and inspections.
Construction work began on the 1650MWe EPR unit at the Normandy site in December 2007. The reactor was originally expected to start commercial operation in 2013, but the date was pushed back to 2017. On 3 September EDF deferred the start-up date by another year. Costs have now tripled from the original estimate. Recently EDF said the project costs have now been further revised to €10.5bn ($11.8bn), up from a December 2012 estimate of €8bn.
Some 98% of the building civil structure has already been completed and 60% of the electromechanical work. The new timetable sets out three key milestones, EDF said. Installation of the primary circuit is now scheduled to be completed in the first quarter of 2016 and system performance testing will begin a year later after all electromechanical work has been completed. Fuel loading and start up is now expected to take place in the last quarter of 2018.
The outcome of the RPV investigations could have a knock-on effect for other EPR newbuild projects. EPRs are also under construction at Olkiluoto 3 in Finland and Taishan 1 and 2 in China. Olkiluoto 3 has been under construction since 2005 and is also facing delays and cost overruns. It is now expected to start up in 2018. Taishan 1, which has been under construction since 2009, is expected to start up in 2016, and Taishan 2 in 2017.