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Areva-Le Creusot at it again! They gave Fessenheim – already considered France’s most dangerous nuclear power station – a steam generator with material defects, further undermining safety. According to the French regulator, ASN: “The steam generators are thus particularly important pressure equipment items. They take part in two key safety functions: cooling of the reactor core and containment of radioactive substances.” (ASN, July 20, 2016)
Fessenheim Rhine Rift
It’s not enough that Fessenheim is old; it’s not enough that “Due to its location, the Fessenheim plant is subject to particular risks from seismic activity and flooding, and there is an ongoing debate about the adequacy of its design in these respects,https://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant

And, Fessenheim appeared on a list earlier this month of French Nuclear Power Stations which are at risk of failure of important safety parts during an earthquake. The list was given by EDF to the Regulator (ASN). This may, once again, be Areva-Le Creusot’s fault, though they don’t say: https://web.archive.org/web/20160715171756/http://www.asn.fr/Controler/Actualites-du-controle/Avis-d-incident-des-installations-nucleaires/Risque-de-defaillance-d-elements-importants-pour-la-protection-en-cas-de-seisme

Areva-Le Creusot is French State owned, as is EDF which owns Fessenheim.

Notice from the French Nuclear Regulator:
ASN suspends the test certificate for a steam generator in the Fessenheim NPP affected by one of the irregularities detected in Areva’s Creusot Forge plant
20/07/2016 4:30 pm Note d’information

ASN has suspended the test certificate it issued to Areva NP in 2012 for a steam generator at present installed on the Fessenheim NPP reactor 2. This suspension follows the detection of an irregularity in the manufacture of one of the parts of this steam generator, called the “lower shell”, manufactured by Areva’s Creusot Forge plant.

The forging process for the lower shell of this steam generator, made in 2008, was not compliant with the technical file submitted to ASN and with the state of the art. ASN was not informed of this nonconformity. Had ASN been aware of this nonconformity, for which there was no particular substantiating documentation, it would not have issued the test certificate in 2012. EDF informed ASN of the consequences of this irregularity in mid-June.

ASN is responsible for monitoring the manufacture of the nuclear pressure equipment that is most important for nuclear safety. On the basis of a review, several inspections and the results of hydrostatic testing during which the equipment was subjected to high pressure, ASN issued test certificates confirming the suitability of this equipment for service. These certificates are required for it to be placed in service.

ASN asked Areva NP to send it a file presenting the approach it intends to adopt to demonstrate the compliance of this steam generator with the regulations.

On 13th June 2016, EDF shut down Fessenheim NPP reactor 2 and on 15th June 2016 sent ASN its initial analysis of the irregularity detected. Until such time as the test certificate suspension is lifted, the steam generator and therefore the reactor must be kept shut down.” (A few words were changed for clarity based on the French.) Original English here: http://web.archive.org/web/20160728055600/http://www.french-nuclear-safety.fr/Information/News-releases/Fessenheim-NPP-affected-by-one-of-the-irregularities-detected-in-Areva-s-Creusot-Forge-plant French here: http://web.archive.org/web/20160728055425/http://www.asn.fr/Informer/Actualites/Fessenheim-l-ASN-suspend-le-certificat-d-un-generateur-de-vapeur ? “ASN asked Areva NP to send it a file presenting the approach it intends to adopt to demonstrate the compliance of this steam generator with the regulations“.? Shouldn’t they replace it?!

Technical notice from the ASN:

Results of the detection of the Flamanville EPR vessel anomaly

The detection of an anomaly in the chemical composition of the central part of the Flamanville EPR vessel closure and bottom heads led ASN to ask Areva NP and EDF to conduct a full experience feedback analysis with regard to this event. Three processes are currently under way:
– on other components of the EDF reactors, the search for technical anomalies similar to that detected on the Flamanville EPR vessel. This search led ASN to issue a communication concerning the channel heads of certain EDF reactor steam generators on 23rd June 2016;
– quality reviews of parts manufactured in the past by the Creusot Forge plant. This review enabled Areva NP to detect irregularities concerning which ASN issued communications on 3rd May and 16th June 2016. The irregularity affecting the lower shell of the Fessenheim NPP reactor 2 steam generator was detected thanks to these reviews;
– initiation of a review of BNI licensee monitoring of contractors and subcontractors, of ASN oversight and of the alert mechanisms.

Steam generator lower shell

The steam generators are heat exchangers which use the energy from the primary system of nuclear reactors to transform the water in their secondary systems into steam, thus driving the turbine producing electricity.

Their exchange system comprises a tube bundle consisting of several thousand tubes through which the primary water circulates at high temperature (320°C) and high pressure (155 bars). These tubes confine the primary system water and allow heat exchange while avoiding any contact between the primary and secondary fluids. The steam generators are thus particularly important pressure equipment items. They take part in two key safety functions: cooling of the reactor core and containment of radioactive substances. 900 MWe pressurised water reactors, such as that at Fessenheim, have three steam generators. Each stands about twenty metres high and weighs about 300 tonnes.

The lower shell of a steam generator is a hollow cylinder more than four metres high and three metres in diameter. It constitutes the lower part of the outer containment of the steam generator’s secondary part. It is made of steel.

Irregularity detected on the lower shell of one of the Fessenheim NPP reactor 2 steam generators

The lower shell of the Fessenheim NPP reactor 2 steam generator was manufactured by Areva NP in its Creusot Forge plant by forging a steel ingot of about 95 tonnes.

The hollow ingot from the steel mill was subsequently forged with a press to create the cylindrical part and stretch it to its final properties and dimensions. During this forging process, the ends of the part are cut and scrapped. Owing to the ingot solidification process, the metallurgical, chemical and mechanical characteristics of these ends are degraded.

In 2008, during forging of the lower shell of one of the steam generators for the Fessenheim NPP reactor 2, Creusot Forge decided not to scrap one of the two ends of the ingot, called the “feedhead”. Most of this is thus present in the final part, which can lead to inclusions being present in the steel and to a local chemical composition of the material which could degrade its weldability, its ageing and its mechanical properties.” English original http://web.archive.org/web/20160728055600/http://www.french-nuclear-safety.fr/Information/News-releases/Fessenheim-NPP-affected-by-one-of-the-irregularities-detected-in-Areva-s-Creusot-Forge-plant (Emphasis our own. Some words changed for clarity, based on the French.)

Click to access GV+FSH+2_note+technique.pdf

Expert opinion on Fessenheim commissioned by Basel, Switzerland: http://web.archive.org/web/20110720000723/http://www.kantonslabor-bs.ch/files/presse/93_3_Expertise-Fessenheim-f.pdf