Reflections on this year's CO2 minimum at the Mauna Loa observatory.

[kristopher]

4. IRREGULARITIES AND ANOMALIES RELATING TO THE FORGED COMPONENTS OF LE CREUSOT FORGE

From Greenpeace:

In late 2014, AREVA notified Autorité de Sûreté Nucléaire (ASN) of the results of material tests carried out on a component manufactured at the Creusot Forge. These tests were undertaken by AREVA as part of the much-delayed Qualification Technique (QT) of components for the European Pressurised Reactor (EPR) presently under construction at the Flamanville 3 (FA3) nuclear power plant (NPP). The part tested was a supernumerary equivalent of each of the two components, the upper and lower head shells, that had already been incorporated into the FA3 reactor pressure vessel (RPV) now installed within the nuclear island at the NPP site.

To much consternation the test results revealed that the material characteristics, particularly the impact or fracture toughness, did not conform to the design-basis specification and, moreover, it arose from a small but nevertheless significant increase in the carbon content across a large zone of macrosegregation present throughout most of the thickness of the equivalent head shell – this is the so-called ‘carbon anomaly’.

In the macrosegregation zones of excess carbon the toughness or resistance of the steel to tearing and cracking is lowered, rendering forged components vulnerable to abrupt and catastrophic failure via rapid crack propagation and fast fracture – the fracture toughness is a particularly important material characteristic of the through-life components of the nuclear primary pressure circuit for which ‘break preclusion’ (ie no opportunity for catastrophic failure) is an absolute prerequisite of the design-basis and nuclear safety case. When applied to the already installed FA3 RPV, such was the seriousness and potential implications of these test results that ASN required AREVA to i) undertake a further test and analysis programme evaluating the risk and acceptability of the FA3 RPV for nuclear power service and ii) review quality assurance practices at the FA3 component manufactory, Le Creusot Forge.

i) AREVA’s Further Test and Analysis Programme of the Carbon Anomaly: The immediate implication of this non-conformity against the design-basis specification of the nuclear safety critical FA3 RPV is certain to stall the analysis and reporting of the test programme of i) until mid-2017, if not later, and quite possibly it will set back the ultimate delivery date for the FA3 NPP – if the non-compliance of the material properties of the FA3 RPV is unacceptable to ensure future, tolerably safe operation then its replacement in the virtually completed nuclear island containment at Flamanville NPP could result in several additional years of delay and involve many millions of Euros to effect remediation.

The present status of the FA3 RPV is that it does not have an ASN issued Certificate of Conformity, meaning that it neither complies with European Pressure Equipment Directive 97/23/EC É quipements Sous Pression Nucléaire of December 2005 (ESPN); nor satisfies the ASN prerequisite of January 2008 that all new components require a Certificate of Conformity before production begins. Moreover, ASN has not made clear whether it has received a request from AREVA for it to evaluate the Creusot manufacturing route(s) in preparation for a retrospective Certificate of Conformity and that, if it has, if this evaluation has been set back by ASN’s recent (June 2016) deprioritisation of the FA3 carbon anomaly investigation.

It is unclear if other AREVA delivered forged components of the FA3 primary pressure circuit (ie the pressuriser, steam generators, etc) also do not have their respective Certificates of Conformity, irrespective of whether these components were sourced from Creusot or an overseas forge such as the Japanese Casting and Forging Company (JCFC) and/or the Japan Steel Works (JSW).
ii) AREVA’s Review of Past Quality Assurance Practices – the Irregularities: The outcome of AREVA’s review of past practises at Creusot, revealed that not only was quality assurance and component conformity unsatisfactory, particularly in that the manufacturing route for the FA3 upper and lower heads had never been subject to QT and thus had not obtained a Certificate of Conformity, but also that these uncertainties involved components that had been manufactured as far back as 1965 – ASN refers to these uncertainties as ‘irregularities’.

The consequences of the irregularities are now coming to light in dribs and drabs, extending back in time to around 400 flawed components produced at Creusot from 1965. When first announced, in April 2016, around about 50 so-called irregularities were identified to be presently installed in operating NPPs across France and, quite possibly, there are others installed in overseas NPPs. Now, late September 2016, the number of irregularities potentially impinging on the safety of French NPPs has risen to 83, 23 of which ASN has evaluated on safety grounds finding that 2 NPPs need to be held in enforced outage for further investigation. The status of the remaining 60 yet to be evaluated irregularities is not known....

Full study at: http://www.greenpeace.org/france/PageFiles/266171/Note_LargeAndAssociates_EN_26092016.pdf


Hinkley builder admits defective parts may be found in nuclear plants around the world
by Zachary Davies Boren June 18, 2016
http://energydesk.greenpeace.org/2016/06/18/flamanville-defective-parts-around-the-world/

The EPR “anamoly;” what’s at stake for Areva
https://safeenergy.org/2015/04/13/the-epr-anamoly/

Areva aware 'as early as 2006' of serious fault in nuclear reactor destined for UK
French state-owned nuclear giant Areva has been aware for almost a decade of critical anomalies in its new generation EPR plant in Flamanville, the same model sold to Britain
http://www.telegraph.co.uk/news/earth/energy/nuclearpower/11727000/Areva-aware-as-early-as-2006-of-serious-fault-in-nuclear-reactor-destined-for-UK.html

07/04/2015 11:30 am Communiqué de presse

ASN has been informed by AREVA of an anomaly in the composition of the steel in certain zones of the reactor vessel head and reactor vessel bottom head of the Flamanville EPR.



EPR reactor vessel

The nuclear pressure equipment regulation requires that the manufacturer limits the risks of heterogeneity in the materials used for manufacturing the components most important for safety. In order to address this technical requirement, AREVA carried out chemical and mechanical tests on a vessel head similar to that of the Flamanville EPR. The results of these tests, in late 2014, revealed the presence of a zone in which there was a high carbon concentration, leading to lower than expected mechanical toughness1 values. Initial measurements confirmed the presence of this anomaly in the reactor vessel head and reactor vessel bottom head of the Flamanville EPR. ASN received a proposal from AREVA for a further detailed test campaign on a representative vessel head, starting in April 2015, in order to precisely identify the location of the zone concerned and its mechanical properties.

ASN will make a decision on the acceptability of the test programme, check its correct performance and examine the file to be submitted by AREVA to demonstrate the robustness of the Flamanville EPR reactor vessel. It will also call on the services of its technical support organisation, IRSN (Institute of Radiation Protection and Nuclear Safety), and the Advisory Committee of Experts for Nuclear Pressure Equipment.

ASN has informed its foreign counterparts which are concerned by the construction of an EPR.

The vessel of a pressurised water reactor is an equipment that is particularly important for safety. It contains the fuel and takes part in the radioactivity second containment barrier.

The reactor vessel head and reactor vessel bottom head of the Flamanville EPR are partially spherical forged steel parts.

Learn more:
Technical clarifications concerning the manufacturing anomalies on the Flamanville EPR reactor pressure vessel
1. Toughness is an indicator of the ability of a material to withstand the propagation of cracks. For a reactor vessel, this property is in particular significant regarding thermal shock, for instance following the injection of cold water in the primary circuit of the reactor. http://www.french-nuclear-safety.fr/Media/Files/Technical-clarifications-concerning-the-manufacturing-anomalies-on-the-Flamanville-EPR-reactor-pressure-vessel

http://www.french-nuclear-safety.fr/Information/News-releases/Flamanville-EPR-reactor-vessel-manufacturing-anomalies