Improving nuclear safety and radiation protection

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Information Letter No.19: ASN actions for monitoring the Flamanville EPR reactor construction site: notable points.

Published on 09/06/2017 • 07:30 pm

Information notice

In the second half of 2016, ASN continued its monitoring of the Flamanville 3 EPR reactor and its various manufacturing operations. The notable points observed over these last few months are detailed below.

View on the EPR Flamanville 3 site from the cliff © EDF Médiathèque - Alexis Morin - Antoine Soubigou / all rights reserved

View on the EPR Flamanville 3 site from the cliff © EDF Médiathèque - Alexis Morin - Antoine Soubigou / all rights reserved

“Pre-service inspection” on the main primary system

By means of spot-checks, ASN verifies the performance of the non-destructive tests required for the main primary system “pre-service inspection” prescribed by the regulations. During this inspection, the licensee is required to check the applicability of the non-destructive examination processes that will be used during operation of the reactor. These processes must first undergo qualification, which consists in describing their performance and, when the risk of the appearance of deterioration has been identified, in demonstrating that this performance is adequate for achieving the required safety objectives, more specifically to allow early detection of flaws.

Following the 12th April 2016 inspection, ASN concluded that the organisation defined and implemented by EDF on the site to ensure the performance, technical inspection and surveillance of the monitored activity was not satisfactory[1]. Following this inspection and pursuant to prescription [INB167-2] of ASN resolution 2013-DC-0347, EDF informed ASN that it had suspended activities concerning the performance of manual non-destructive tests for the pre-service inspection of the main primary system.

Further to a large-scale action plan implemented by EDF, ASN was informed of the resumption of the above-mentioned activities. ASN carried out an unannounced inspection on 17th November 2016 to check the organisation defined and implemented on the site for performance of the pre-service inspection. Following this inspection, ASN considered that this organisation was satisfactory and that the programme of corrective measures defined following the 12th April 2016 inspection had indeed been implemented.

Equipment conservation

In addition to the field check performed during the inspections, ASN carries out spot-checks of the deviations detected by EDF and verifies that they are adequately processed.

Given the reactor commissioning times announced by EDF and further to the deviations encountered on the new heat exchangers, ASN asked EDF to take full account of the lessons learned from the equipment conservation deviations. EDF analysed all the elements supplied by the equipment manufacturer to identify the underlying causes of the corrosion phenomena observed: a programme to restore the conformity of the exchangers concerned was defined, along with an inspection programme for similar equipment items when they are connected to the systems. Finally, EDF specified the conservation procedures that its teams will be implementing following system rinsing. ASN carried out a progress briefing with EDF on these deviations during the inspection on 1st and 2nd September 2016.

ASN considers that EDF must remain vigilant regarding the correct conservation of the equipment already installed, taking account of the impact of filling the systems with water for the hydrotests and the start-up tests, as well as the conditions of the worksite, more particularly the risks entailed by the ongoing activities in the vicinity of the equipment.

Addressing the risk of foreign material entering the systems

As construction progresses, in particular as equipment cleaning proceeds, countermeasures must gradually be put into place to prevent the risk of foreign material entering the systems. At the beginning of 2016, ASN drew the attention of EDF to the need to implement a dedicated organisation such as that which exists on the reactors in operation. EDF thus defined an appropriate reference baseline for gradually dealing with this risk and notably implemented it for assembly of the fuel storage racks in the fuel building pool.

ASN carried out an inspection on 9th November 2016 concerning the assembly of the fuel storage racks and considers that the organisation defined and implemented on the site for installation of this equipment in the pool could be improved, given the deviations in the provisions adopted for management of the risk of entry of foreign material and the cleanness of the fuel building pool.

ASN remains vigilant with regard to appropriate handling of the risk of foreign material entering the systems as a result of the progress of the construction site.

Reinforced inspection of personnel radiation protection

During the course of 2016, ASN carried out reinforced inspections of several NPPs on the topic of radiation protection. The inspection on the EPR construction site at the beginning of October involved nine ASN inspectors and two IRSN experts and covered the following topics: general site organisation, check on compliance with design provisions, check on compliance with baseline requirements (safety analysis report, general operating rules) and management of radioactive sources. The inspection was conducted in part at night, to examine the conditions of use of the radiographic inspection equipment utilising high-level sources.

In the light of the results of this spot-check examination, the organisation defined and implemented on the site for personnel radiation protection appeared to be on the whole satisfactory. However, the licensee will be required to provide answers to the requests from the inspectors, more particularly with regard to:

  • the administrative status and storage conditions of certain radioactive sources on the construction site;
  • the consistency between the requirements applied at installation of the equipment and those in the safety analysis report;
  • management of the waste resulting from the surface contamination checks in the radiography equipment storage area;
  • when processing installation deviations, taking account of radiation protection of workers during future operation of the reactor;
  • the strategy for installation of radioactivity detection monitors on the nuclear island.

Monitoring of the Flamanville 3 EPR reactor start-up tests

ASN continued its oversight of the preparation for and performance of the EPR reactor start-up tests. Two inspections were carried out in October 2016 on the first start-up tests for the ultimate heat removal system (SRU), which is a specific feature of the EPR. The inspectors notably examined the assembly completion checks and the preliminary equipment tests, the preparation for the system functional tests and the extent to which the future EPR reactor licensee made use of the start-up tests to validate the operating procedures.

In the light of the results of this spot-check examination, ASN considers that the organisation defined and implemented on the site for the preparation and performance of the start-up tests appeared to be on the whole satisfactory. However, the organisation defined and implemented to make use of the start-up tests to validate the operating procedures could be improved. Despite a specific organisation, it would however appear necessary to ensure that procedures are drafted with the same level of operational detail as that required for future operation, prior to having them validated during the start-up tests.

Protection of the environment

On 7th July 2016, ASN carried out an inspection on the topic of protection of the environment. This inspection was preceded by a number of ASN questions and comments on the environmental reports. The inspectors checked solvents emissions monitoring procedures, the performance of periodic checks on certain equipment items and compliance with various prescriptions. The inspectors also visited the water pumping facilities, the excavated material disposal area and the site internal waste transit zone. In the light of the results of this spot-check examination, the organisation defined and implemented on the site for protection of the environment appeared to be inadequate. ASN in particular considered that the licensee would need to identify all the equipment contributing to protection of the environment and then employ greater rigour in its utilisation.

Since then, ASN has examined EDF’s corrective measures and substantiating documentation and considers that this has reinforced the rigour of the periodic inspections and the exhaustiveness of the internal baseline requirements for the equipment concerned by protection of the environment. ASN oversees the monitoring of the operations to remove and dispose of legacy waste inadvertently discovered in May 2016 during work to bury rainwater piping. Since mid-2016, this waste – consisting primarily of plastics, wood, cables and metal pipes – which was in principle buried at the end of the construction of Flamanville reactors 1 and 2, is gradually being uncovered, taken away and disposed of by EDF.

Checks on the preparedness of the future licensee of Flamanville 3

While overseeing the manufacture of components, their qualification, construction, reactor start-up tests and examining the commissioning authorisation application, ASN is also monitoring the preparedness of the future licensee of the Flamanville 3 EPR reactor. The inspectors notably verify the various operating organisations, personnel skills management and the procedures for drafting the future operating documentation.

In this respect, ASN carried out two inspections in the second half of 2016 devoted to operational preparedness. On the basis of the results of this spot-check examination, ASN considers that:

  • the organisation defined and implemented on the site for managing safety and organisational and human factors is appropriate;
  • the organisation defined and implemented on the site to prepare for emergency management could be improved on various points. More specifically, the future licensee must improve the local emergency resources commissioning programme and ensure that the future emergency team members are adequately trained.

ASN will continue its oversight in this field to ensure that the future licensee of the Flamanville EPR reactor is capable of exercising in full its responsibility as nuclear licensee at commissioning of the reactor.

ASN position regarding the management of severe accidents in the EPR design and level 2 probabilistic safety assessments

On the basis of an analysis carried out by IRSN and after consulting the advisory committee for nuclear reactors (GPR), ASN issued a position statement on 13th July 2016 on the design provisions of the Flamanville 3 EPR reactor for management of severe accidents (accidents with fuel melt), as well as on the probabilistic safety assessments (level 2 PSA) quantifying the possible releases of radioactive substances in the event of an accident.

ASN takes a positive view of the fact that the design of the Flamanville 3 EPR reactor takes account of severe accidents, with the aim of limiting the population protection measures necessary in these situations. ASN considers that the severe accident management provisions implemented for the Flamanville 3 EPR reactor are satisfactory.

ASN more specifically considers that:

  • subject to an additional demonstration of the correct qualification of the primary system depressurisation valves in severe accident conditions, EDF’s intended design for the primary system depressurisation systems does, as required, “practically preclude” potential core melt situations with a primary system at pressure;
  • subject to demonstration of the qualification of equipment for severe accident conditions:
  • the design of the corium (molten core) recovery and cooling system outside the reactor vessel and the presence of material arrangements for the retention, transfer, spreading and cooling of the corium are in compliance with the requirements of the Flamanville 3 EPR creation authorisation decree (DAC) and the ASN prescriptions;
  • the tightness of the internal wall of the reactor building containment is satisfactory in the conditions set out by the Flamanville 3 DAC and the ASN prescriptions.

ASN considered that the functional and physico-chemical hypotheses used by EDF to evaluate atmospheric releases in the event of a severe accident were acceptable, but considered it necessary to study potential leaks from the ultimate heat removal system in a severe accident, to allow a better analysis of the management of these potential situations.

 

1  Consult

Date of last update : 15/06/2017