EPR Reactor: Information Letter n°22 : Monitoring the construction of the Flamanville-3 EPR reactor: the notable actions of ASN in 2019 and early 2020

Published on 27/07/2020 at 10:37

Information notice

ASN continued its monitoring of construction of the Flamanville EPR reactor. ASN was particularly vigilant regarding the processing of the anomalies detected on the main secondary system welds and the continuation of the reactor start-up tests. Review of the notable events.

Consequences of the Covid-19 epidemic

During the emergency lockdown period due to Covid-19, the majority of the construction and testing activities were suspended. From 17 March 2020 until the end of April, the only activities maintained were:

  • conservation of the equipment,
  • monitoring of the facility,
  • monitoring of the site,
  • preparation of the repairs of the main secondary system welds.

ASN continued its regular monitoring of the situation during this period.

Anomalies detected in the main secondary system welds

In 2017, EDF informed ASN of anomalies that had occurred during welding of the main steam letdown pipes (VVP system) of the Flamanville EPR reactor. These pipes are subject to a "break preclusion" approach, which implies tightened design, manufacturing and in-service monitoring requirements such that it can be considered, with a high degree of confidence, that a break of these pipes is extremely improbable. ASN's inspections revealed a lack of proficiency in the welding operations performed on the VVP pipes and deficiencies in EDF's monitoring of its service providers (see EPR Newsletter No. 21).

In 2018, EDF undertook to repair the welds concerned, except for the eight welds located between the two containments of the reactor building, which are not readily accessible. In December 2018, EDF sent ASN a file aiming to demonstrate that the quality of these eight welds was sufficient and that their failure could be ruled out with a high level of confidence.

ASN's examination of the EDF file, with the support of IRSN (French Institute for Radiation Protection and Nuclear Safety), continued in 2019 with the consultation of the Advisory Committee for Nuclear Pressure Equipment (GP EPSN) on 9 and 10 April 2019, which considered that EDF should repair these eight welds or else abandon its break preclusion approach concerning them, which would necessitate modifying the reactor to take the possibility of such breaks into account in its safety case.

In a letter dated 30 July 2019, EDF informed ASN that it would repair the eight welds to bring them into compliance before reactor start-up. Three work scenarios were presented to ASN, which issued a preliminary opinion on the potential implementation difficulties identified by EDF. EDF has now favoured the option of repair via the pipe interior. The work processes are currently being qualified, with work completion targeted for the second half of 2021.

Alongside this, the examination of the elements - which began in 2019 - prior to the repair of the other VVP pipe welds, has continued since the start of the year with the aim of proving compliance with the break preclusion baseline requirements. It is planned to start the repair operations as from the second half of 2020.

At present, about one hundred welds of the EPR reactor systems require repair work. This number is liable to change according to the results of the EDF re-inspection programme.

Anomaly in the stress-relief heat treatment of certain permanent assemblies of the steam generators and the pressuriser

In August 2019 Framatome informed ASN of noncompliance with the stress-relief heat treatment temperatures in certain welded assemblies. Certain welds of the EPR steam generators and pressuriser are concerned by this process which is implemented in the Saint Marcel manufacturing shop (Saône-et-Loire département).

Framatome and EDF submitted elements to ASN supporting, despite this deviation, the possibility of performing the hot tests without jeopardising personnel safety or the integrity of the equipment items concerned.

The manufacturer is currently defining a strategy to address the anomaly affecting the EPR equipment. It is in line with the overall strategy for dealing with this anomaly, which also concerns spare equipment items intended for the reactors currently in service. ASN will examine this strategy once it has been defined.

In its work to address the EPR equipment anomaly, Framatome has produced a scale-1 mock-up simulating the stress-relief heat treatment of a permanent assembly between shells in order to assess the extent of the anomaly affecting the EPR steam generator permanent assemblies.

Monitoring the start-up tests

ASN continued monitoring the preparation and performance of the reactor start-up tests, which underwent nine inspections during the course of 2019 and early 2020. These inspections essentially concerned the "hot tests". The inspectors more particularly examined the rigorousness of the preparation for and performance of the tests, the documentation and the processing of any deviations detected, and the organisation put into place by EDF to decide whether to continue with the general start-up tests programme.

As the hot tests constitute an important phase in the verification of the facility safety case, ASN decided to subject them to a tightened inspection. This tightened inspection conducted from 3 to 6 December 2019 involved a team of eight ASN inspectors assisted by experts from IRSN. It was organised as follows:

  • one team inspected the organisation defined by EDF: management of start-up test experience feedback, examination of the first results and first-level analysis, configuring of the instrumentation and control;
  • two other teams focused on the way in which the ongoing tests were performed and the daily activity of the testers: management of the tests from the control room, conformity of the line connections, modifications made to the installation to allow performance of the tests, etc.


This inspection revealed the following main points:   

  • progress has been made in the preparation and documentation of the tests in view of the points noted in the first inspections;
  • the management bodies could fail to capture information, thereby losing opportunities to better manage the organisation of the tests;
  • the condition and cleanliness of the facilities deteriorated during the hot tests;
  • the representativeness of the test results remains to be demonstrated, particularly in the areas of instrumentation and control and the tests conducted on temporarily-modified facilities.

In the light of this random sampling check on the performance of the tests on the site and of their documentation, ASN considers that the organisation of the start-up tests as defined and implemented on the site is on the whole satisfactory. Further to ASN’s requests, EDF improved the rigorousness of the test documentation and how it informs ASN with regard to the general performance of the tests. EDF must continue to focus on the rigour of preparation for and performance of the start-up tests, by improving the demonstration of the representativeness of the tests for which procedural adaptations and temporary modifications of the facility are implemented.

Review of the quality of the Flamanville 3 reactor equipment

The numerous anomalies discovered during the production and inspection of the main secondary system welds, along with the deviations discovered during ASN inspections or addressed as significant events since the start of the project have led ASN to express the finding of a deficiency in EDF's monitoring of its outside contractors. This finding led ASN to ask EDF to perform a quality review of the Flamanville EPR reactor equipment.

EDF conducted additional inspections as of 2018 through a review programme, which was amended in late 2018 to integrate ASN's request to extend the review to cover a wider range of equipment and subcontractors. ASN receives periodic reports on the progress of this programme, and a first results assessment is to be submitted to ASN this year.

During an inspection held on 27 June 2019, ASN assessed the preparation and implementation of the EDF review programme by examining the information produced to substantiate the adequacy of the actions taken, the definition of the conditions of performance and documenting of the review, and examining concrete cases. In the light of this random examination and the first answers received, ASN considers that EDF must further supplement its additional inspection programme conducted as part of the equipment quality review and apply it rigorously.

Taking into account the risk of fraud

As part of its action plan to take into account the risk of fraud, ASN conducted two inspections on the Flamanville 3 EPR site in 2019.

The first inspection concerned EDF: the inspectors examined the measures implemented locally by EDF with respect to the fraud risk then checked actual cases, essentially on the basis of information relative to anomalies detected on the construction site and which could present a risk of infringement. In the light of this random examination, EDF was to set up an ad hoc organisation and initiate a number of awareness-raising and verification measures, and this has now been done. EDF must also be particularly attentive to the documenting of the methods of proof and safeguarding the first data recording, particularly in a work site context.

The purpose of the second inspection, conducted on the auxiliary pipes, was to verify that the manufacturer Framatome has met its commitments following ASN's requests concerning the prevention, detection and processing of irregularities. The inspectors noted positively that steps had been taken to enable Framatome quality control to take better account of the detection of irregularities in the technical documentation, and the test reports in particular. The inspectors nevertheless noted that the technical provisions they analysed for the prevention and detection of these irregularities among Framatome subcontractors were not sufficient.

Monitoring of the preparedness of the EDF teams responsible for future operation of the Flamanville 3 reactor

The inspectors verify the defining and progressive implementation of the various operating organisations, the management of personnel skills and the methods of preparing the future operating documentation in order to ascertain that the teams will be ready to fully exercise their responsibilities at the end of partial commissioning and subsequent reactor commissioning.

In this respect, ASN carried out three inspections in 2019 devoted to preparation for EPR operation. In the light of this random examination, ASN considers that the organisational set-ups defined and implemented on the site for counting the situations and physical stresses affecting the nuclear pressure equipment, the performance of the pre-service inspection and the involvement in the performance of the hot tests are satisfactory.

ASN nevertheless considers that a substantial amount of work remains to be done, particularly regarding the production of the operational management documentation, between now and reactor commissioning to prepare the teams tasked with the future operation of the reactor. ASN will continue its monitoring in this area in order to ascertain that the teams tasked with future operation are capable of fully exercising their responsibility as nuclear licensee in these phases.

Pre-OSART mission conducted by international experts

A "Pre-OSART" (Pre-Operational Safety Review Team) mission was held on the Flamanville 3 EPR reactor construction site from 17 June to 4 July 2019. The Pre-OSART missions are organised by the IAEA (International Atomic Energy Agency) at the request of the nuclear regulator of each Member State. Carried out by teams of about ten experts of various nationalities, these missions involve a critical in-depth examination of the safety organisation and practices of nuclear power plants (NPP) before they are commissioned.

On 4 July 2019, the team of experts gave an oral account of its main conclusions. Its conclusions are on the whole positive and emphasise the strong safety culture of the site's senior management and teams, and its continuous improvement in terms of safety. The experts thus identified eight good practices and made six recommendations and fifteen suggestions. The recommendations and suggestions will be laid down in a dedicated action plan, the results of which will be assessed through a follow-up mission, which is generally carried out eighteen months after the initial mission. ASN is examining attentively the report it has been submitted and takes the report's conclusions into account its own inspection actions.

Monitoring of the Flamanville EPR engineering activities

In 2019, ASN carried out inspections in the EDF engineering departments tasked with the detailed design of the Flamanville reactor 3, on the theme of equipment qualification for accident conditions, the analysis of the results obtained during the start-up tests and the processing of deviations.

With regard to equipment qualification for accident conditions, ASN monitored the progress of the action plan implemented by EDF further to the compliance notice decision of 25 February 2019. On 27 September 2019, ASN carried out an inspection to check renewed compliance with the provisions of the Order of 7 February 2012. The inspectors observed that EDF had carried out a substantial amount of work to list the reservations and reconstitute their processing. The random examination carried out during the inspection revealed that the actions and the way they are implemented are satisfactory and ensure the traceability of the qualification reservations in accordance with Article 2.5.6 of the Order of 7 February 2012.

ASN is monitoring the progress of the action plan defined and implemented by EDF to guarantee that the qualification of the equipment installed on the Flamanville 3 site is maintained.

ASN inspects the activities to analyse the start-up test results obtained by the EDF engineering departments. These inspections also address the processing of deviations and the management of post-test modifications, in order to assess the measures taken to control the effects of these modifications on the test results. The inspection carried out at the CNEPE (EDF's National Centre for Electricity Generating Equipment) on 27 November 2019 revealed shortcomings, particularly in taking account of the effects of the cumulative modifications on the tests results. The inspection also revealed that the rate of analysis of the test results does not match the rate of performance of these tests. ASN will verify the corrective actions implemented by EDF further to these findings and will continue to monitor the start-up test results analysis activities in 2020.

During an inspection carried out on 7 November 2019, ASN also checked the measures implemented by EDF to detect and deal with deviations. This check found that the process applied by EDF to deal with deviations is satisfactory. It is nevertheless necessary to shorten the times taken to characterise and take into account the cumulative effect of deviations. ASN will monitor the actions defined by EDF for these points.

Monitoring of the activities carried out by the suppliers and EDF's monitoring of its suppliers

ASN can be obliged to inspect companies providing services to EDF. This can concern, for example, equipment manufacturers or holders of contracts for services provided on the construction site. Thus, in July 2019, an inspection focusing on the processing of deviations and EDF's monitoring of protection important activities carried out by the supplier SPX Clyde Union was conducted on the supplier's premises. This inspection more specifically concerned the handling of the deviations observed on the medium pressure safety injection system pumps (RIS MP pumps). The inspectors were thus able to assess the compliance work performed on these pumps and EDF's monitoring of this work. ASN will remain attentive to the steps that still have to be taken to demonstrate the reliability of these pumps and ensure the traceability of monitoring actions.

An inspection was carried out in January 2020 at Framatome to check EDF's monitoring of the development of the Flamanville EPR reactor protection system software. At the end of this inspection, the inspectors deemed that the current management of skills, modifications and deviations is satisfactory. ASN nevertheless noted that the performance and monitoring of protection important activities can still be improved. ASN will monitor the actions undertaken by EDF in this respect.

Checking the control of detrimental effects and protection of the environment on the Flamanville EPR.

In 2019, ASN conducted an inspection on the theme of environmental protection (INSSN-CAE-2019-0128) which was organised as part of a tightened inspection campaign in the NPPs in Normandy. Thus, on 4 and 5 June 2019, three teams of ASN inspectors accompanied by experts from IRSN, conducted a random inspection of the organisation implemented by the Flamanville 1 and 2 NPP and Flamanville 3 (EPR) for the prevention of pollution, control of discharges and management of the non-radiological risks in the facilities. The inspectors also conducted a sampling inspection of the site's organisation for managing the environmental protection actions.

This inspection served to check, over the Flamanville 3 perimeter, the management of the oil removers, the network of piezometers for monitoring the water table, the ducts and pipes carrying hazardous substances and mixtures, the explosion risk in the gas storage yards, the fire risk and the non-radiological risks.

The general organisation of the site for the control of detrimental effects and the protection of the environment was deemed satisfactory. The inspectors nevertheless noted that the organisation for checking regulatory compliance could be improved, therefore EDF must be particularly attentive to this in view of the future commissioning of Flamanville 3.

Continued examination of the commissioning authorisation application file (DMES) and the partial commissioning authorisation application file (DMESp) for Flamanville 3

 ASN is continuing the examination of the commissioning authorisation application file submitted on 19 March 2015. This file contains the safety analysis report, the general operating rules, a study of waste management, a decommissioning plan, an on-site emergency plan and an updated impact assessment. A new version of the general operating rules was sent to ASN in April 2019.

More specifically, ASN is currently continuing its examination of the initial demonstration of equipment qualification for accident conditions and of the chapters of the general operating rules.

In addition, ASN and EDF held several meetings to define the content of the start-up tests assessment required by the prescription [INB 167-50-1] of resolution 2013-DC-0347 of 7 May 2013. This assessment can be used to determine the conformity of the as-built installation with the provisions of the creation authorisation decree and the requirements concerning reactor design and construction. This assessment will be examined.

Furthermore, the times needed to repair the main steam letdown pipes have led EDF to define a long-term conservation strategy for the equipment installed on the site. This strategy has been discussed between ASN and EDF. Its deployment will be checked by ASN.

At the same time, ASN is continuing its examination of the partial commissioning authorisation application concerning the reception of fuel assemblies. The public consultation procedure will be initiated before this authorisation is issued. 

International experience feedback follow-up

ASN participates in several international bodies and regularly organises meetings with the nuclear regulators concerned by the various EPR projects across the world, which enables it to gather feedback on the construction, tests and operation of this reactor. ASN regularly checks that EDF duly integrates international experience feedback.

Published on 28/02/2019 at 11:12

Flamanville EPR equipment

In a resolution of 25 February 2019, ASN served EDF with formal notice to produce and save proof of qualification of the Flamanville EPR reactor equipment.

Published on 12/04/2019 at 09:00

Flamanville EPR reactor

On 9 and 10 April 2019, ASN convened its Advisory Committee for Nuclear Pressure Equipment (GP ESPN) concerning the approach proposed by EDF to deal with the deviations detected in welds on the main steam transfer pipes of the Flamanville EPR reactor. Representatives from the Flamanville CLI, the HCTISN, the ANCCLI and foreign safety regulators concerned by the construction of an EPR reactor attended this session as observers.

Published on 29/10/2019 at 12:48

Manufacturing deviation at Framatome stress-relieving heat treatment of welds

On 9th September 2019, EDF informed ASN of a deviation concerning the manufacture of nuclear pressure equipment installed in its reactors, and primarily steam generators. During the stress-relieving heat treatment applied to the welds made to assemble nuclear pressure equipment components, the required temperature range has not been respected over the entire area to treat.

Date of last update : 25/07/2023