The French nuclear safety authority (ASN) has reported on its monitoring of the Flamanville 3 EPR construction during the first half of 2013.

Work included monitoring of the reactor dome installation in July, as well as oversight of nuclear pressure equipment installation, and work to prepare for operation of Flamanville 3. ASN said it is now focusing on monitoring the concreting of the internal containment wall of the reactor building.

Dome inspections

ANS carried out three site inspections during the installation of the reactor-building dome, which began on 16 July and was completed in August once EDF had welded the dome to the liner cylinder.

"Inspections showed that the prior lifting tests were correctly performed," ANS said. It also noted that teams in charge of Flamanville 2 were kept "regularly informed" of the operation. Flamanville 2 is in close proximity to the EPR construction site and could be impacted should the crane topple or drop its load. Finally, the inspectors noted the high standard of EDF’s monitoring of the contractors welding the liner.

Incorrect valve installation

Following the incorrect installation of a valve of the safety injection system, the regulator asked AREVA NP to make the necessary changes in the organisation and the nuclear pressure equipment installation documentation.

Installation of the valves and pipes of the safety injection system began on 10 June 2013. Initial work involved installing and welding four valves (called "3-way valves") that constitute fixed points from which the other equipment items are assembled.

ANS said that it was informed "at the beginning of July 2013" that the first of these valves had been installed upside down. An analysis revealed that this resulted "firstly from human and organisational-related factors and secondly from shortcomings in the specification of the requirements applicable to the installation operations and their monitoring."

In early September 2013, AREVA NP submitted a method for identifying and correcting all the shortcomings in the technical documentation used for the first installation sequence. ASN said that the method proposed allows continuous improvement in the documentation while guaranteeing application of all the associated requirements, and it authorised the resumption of the installation operations on 24 September.

Move to commissioning

Also in September 2013, ASN carried out an inspection on the organisation that will be responsible for operation of the Flamanville plant. Gradually, transfer of the responsibility for operation and maintenance of the structures, systems and components will be transferred from the Flamanville Development organization to the future operator Flamanville NPP.

ASN concluded from this inspection that the organisation defined and implemented by the Flamanville 3 NPP is satisfactory.

It found that nuclear power plant staff had "developed specific computer aids adapted to the transfer activities and allowing, for example, real-time verifications to be carried out on the ground thanks to the use of tablet computers."

EDF began construction of the 1650MWe Flamanville 3 EPR in Normandy, France on 3 December 2007. The reactor, which was initially expected to have a 54-month construction time, is due to start-up in late 2016.

Photo: ANS monitors the installation of the Flamanville 3 Dome in July (Source: ANS)