The ASN Commission calls EDF and Framatome to a hearing on the Flamanville EPR reactor project
On 7th February 2018 the ASN Commission heard EDF and Framatome1 management on the Flamanville EPR reactor project.
The Commission questioned EDF and Framatome more specifically on the anomalies affecting the nuclear pressure equipment, the reactor start-up tests, and the ongoing technical examinations relating to the facility commissioning authorisation application.
Deviations detected in certain welds on the main steam transfer lines2
The ASN Commission questioned EDF and Framatome (formerly Areva NP) about the deviations detected in welds on the main steam transfer pipes. ASN was notified of the first deviations in early 2017.
These lines are subject to a "break preclusion" procedure which implies tightened design, manufacturing and in-service monitoring requirements. These tightened requirements must be sufficient for a break of the lines to be considered extremely improbable. They relieve the licensee of the obligation to conduct an exhaustive analysis of the consequences of a break of these lines in the facility's safety case.
In order to achieve the expected high standard of manufacturing quality, the licensee (EDF) and the manufacturer (Framatome) have defined, more specifically, tightened requirements for the mechanical properties. However, these tightened requirements were not specified to the subcontractor responsible for these welding operations. The controls carried out during production showed that, for some of these welds, not all of these requirements had been met.
Following an inspection by ASN, this finding was extended to other welds on these pipes on the Flamanville site.
Technical discussions held in 2017 led ASN in February 2018 to ask EDF to provide it with a complete file addressing:
- the history of the detection and handling of these deviations;
- the different possibilities for correcting them.
The Commission informed EDF and Framatome that it will obtain the opinion of the Advisory Committee of Experts for Nuclear Pressure Equipment (GP ESPN) on this subject in the second half of 2018.
RPV closure head and bottom head anomaly
On 7th April 2015, ASN made public the discovery of an anomaly in the composition of the steel in certain zones of the reactor pressure vessel (RPV) closure head and bottom head of the EPR reactor. It issued its opinion concerning this anomaly on 10th October 2017.
The ASN Commission reminded EDF and Framatome that commissioning of the RPV is subject to an authorisation delivered with regard to the substantiation of the fitness for service of all of its components. A hydrostatic test of the entire main primary system, which includes the RPV, was carried out on 5th January 2018.
Framatome plans to submit a file to ASN supporting the RPV commissioning authorisation application in the 2nd quarter of 2018. The examination of this file could lead ASN to adopt a position on the commissioning of the RPV before the end of the 3rd quarter 2018.
Reactor start-up tests
The ASN Commission informed EDF that it considers that the organisation in place on the work site can be improved. EDF must in particular reinforce the monitoring of performance of the tests and the handling of any deviations encountered. ASN also expects EDF to inform ASN more diligently on the progress of the startup tests. EDF has undertaken to implement a plan of action to remedy these malfunctions.
In 2018, ASN shall be particularly attentive to the performance of the startup tests, which constitute a major factor in the demonstration of compliance of the facility with its baseline requirements.
Ongoing technical examinations relating to the facility commissioning authorisation application
The ASN Commission has underlined that a significant amount of work remains to be carried out by EDF and Framatome before fuel is loaded into the reactor, in order to justify firstly the fitness for service of the nuclear pressure equipment, and secondly the performance of the safety systems.
This hearing gave the Commission the opportunity to spell out its expectations concerning the ongoing technical examinations, which will lead it to make a position statement with regard to the applications for authorisation to use radioactive materials during the tests, to introduce nuclear fuel onto the site and for reactor commissioning.
ASN will submit its draft resolution on the Flamanville EPR reactor commissioning authorisation application to public consultation.
To find out more:
Consult the technical notice: Flamanville EPR reactor deviations detected in certain welds on the main steam transfer pipes
1. These pipes of the main secondary systems transport the pressurised steam produced in the steam generators to the turbine. Most of these lines are situated within the reactor containment. These pipes are subject to the regulations governing nuclear pressure equipment.
2. Framatome (formerly Areva NP) is responsible for the design, procurement, construction and commissioning of the nuclear steam supply system and the operational and safety instrumentation and control system.