Supervision of the EPR reactor

The EPR reactor is a pressurised water reactor (PWR) whose design, which has evolved with respect to that of the PWRs currently in operation in France, is intended to meet more stringent safety objectives.

ASN’s supervision principles for the construction of the Flamanville-3 reactor

On 10th April 2007, after consulting ASN, the Government issued the creation authorisation decree for the Flamanville reactor No.3, an EPR (European Pressurized water Reactor) reactor.

ASN's oversight of reactor construction falls within the general framework of the regulations applicable to basic nuclear installations supplemented by several ASN resolutions specifically concerning the EPR construction site (see Regulations tab).

In this context ASN:

  • oversees reactor construction to ensure that it ultimately results in a reactor that meets the design requirements;
  • examines the documents relative to the commissioning authorisation application provided for in article 20 of Decree 2007-1557 relative to basic nuclear installations.

ASN's oversight of the Flamanville reactor 3 construction involves the following activities:

  • oversight of the construction work, the manufacture and qualification of the EPR equipment,
  • assessment of nuclear pressure equipment conformity, particularly with regard to design, the manufacturing, assembly, installation and commissioning operations;
  • oversight of the on-site start-up tests,
  • technical examination of the design of the reactor and its equipment, and more specifically examination of the reactor commissioning application documents,
  • assessment of the preparedness of the entity responsible for future operation of the reactor (the FLA3 NPP).

The principle regarding nuclear safety is thatprime responsibility lies with the licensee (EDF).

The objective of ASN oversight is therefore to ensure that EDF exercises its prime responsibility in full and controls:

  • the conformity of the detailed design studies with respect to safety requirements;
  • the conformity of the equipment production or installation activities, with the ultimate aim of assessing the overall quality of work performance;
  • the impact of the worksite on the safety of the neighbouring BNIs and on the environment.

ASN directly oversees the design and manufacture, particularly by Areva, of the main nuclear pressure equipment (for example: the reactor vessel, the steam generators, and the pressuriser).
ASN is also responsible for labour inspection on the construction site.

ASN exercises its oversight through:

  • examination of the detailed design documents;
  • an inspection programme that addresses the activities of EDF's engineering services, the worksite and the manufacturers;
  • examination of the handling of nonconformities or anomalies that can arise on a construction site of this scale. Under the Order of 7th February 2012[1], anomalies or deviations that arise during construction must be recorded and be dealt with by the licensee.

ASN receives technical assistance from the IRSN teams in its oversight activities.

With regard to labour inspection, the ASN inspector determines its oversight actions according to information brought to his/her knowledge, worksite progress and the ongoing operations. Oversight hinges around the examination of files, conducting inspections and the various requests made to the labour inspector.        
To ensure successful oversight of the construction work, ASN relies primarily on:

  • its Caen regional division, where a specific team carries out the worksite inspections and examines the handling of anomalies and non-conformities;
  • its Nuclear Pressure Equipment Department (DEP) where a team is responsible for oversight of the manufacture of nuclear pressure equipment;
  • its Nuclear Power Plant Department (DCN), which is responsible for examining the detailed design, inspections in the EDF engineering services and good coordination between the various ASN entities.

These activities mobilise the equivalent of 15 full-time ASN employees, as well as the personnel mobilised by IRSN.


[1] Order of 7th February 2012 setting the general rules concerning basic nuclear installations.

Date of last update : 22/06/2016