A large proportion of France’s nuclear fleet has been shut down for inspection by the country’s Nuclear Safety Authority following the discovery of potentially faulty components made by Areva using Japanese sourced steel.
In June EDF’s Fessenheim 2 nuclear reactor was shut down for testing by the NSA following problems with parts discovered at an Areva manufacturing facility. Areva announced at the end of April that it had found "anomalies" at its Creusot manufacturing facility during an audit it launched following the discovery of errors in the production of the steel cover for the reactor vessel for the new European Pressurised Reactor, a third-generation reactor design considered by many to be the most advanced and safest in the world. In all 18 reactors were potentially affected by this discovery.
On 20 October ASN called for the shutdown and inspection of five more nuclear reactors for safety checks. The reactors exhibited a high level of carbon in constructional steel which could lead to various failures.
The Nuclear Safety Authority (ASN) has asked owner EDF to carry out additional inspections at Fessenheim 1,Tricastin 2 and 4, Gravelines 4 and Civaux 1 reactors. These reactors are located across the whole of France, close to towns and communes.
“The performance of these inspections will require shutdown of the reactors concerned,” ASN stated. The watchdog wants to check “certain channel heads of the steam generators on five of its reactors, in which the steel is affected by a high carbon concentration.” According to ASN’s analysis the channel heads in “contain a significant carbon concentration zone which could lead to lower than expected mechanical properties.” ASN is demanding that the safety checks be carried out within three months – because the abnormalities could lead to failures in mechanical properties and even to leaks or explosions.
The five reactors under scrutiny are among 18 at which ASN found abnormalities in June. Of the 18 reactors ASN says that six could be restarted after inspection. Seven others (Bugey 4, Civaux 2, Dampierre 3, Gravelines 2, Saint-Laurent-des-Eaux B1 and Tricastin 1 and 3) are being inspected and awaiting reboot.
On 25 October Greenpeace in Japan issued a statement calling into question the safety of the French reactors and by implication all reactors worldwide that had installed potentially flawed components made from the Japanese-manufactured steel.
The threat to nuclear reactor safety in Japan is due, it says, to the supply of steel components to the nuclear industry from both Japan Casting and Forging Company (JCFC) and the Japan Steel Works (JSW).
According to a technical report released in October by Greenpeace Japan, compiled by the nuclear engineering consultancy, Large&Associates of London, evidence of extremely high levels of excess carbon far outside regulatory limits, with the associated loss of steel toughness and significant increase in the risk of catastrophic failure of primary containment components, have been discovered in JCFC-manufactured components installed in steam generators in 12 reactors owned by EdF. The independent French nuclear agency, IRSN, recently warned that due to the excess carbon content, there was an increased risk of failure of the affected steam generators leading to a potential reactor core meltdown.
These components are so fundamental to reactor safety, and consequences so potentially severe, that in every country with nuclear reactors regulators require that these components must not have any possibility of failure under any operating circumstance over the lifetime of the reactor – so-called break-preclusion for the reactor safety case. For this reason the French regulator warned its worldwide counterparts, including the Nuclear Regulation Authority (NRA) in Japan, of the potential enormity of the situation should their nuclear power plants have similarly flawed components installed.
Greenpeace’s contention is that during the period 1994-2006, JCFC supplied flawed components to France, which somehow managed to pass through the quality assurance controls of JCFC, the supplier Areva, and the French regulator to be installed in operating reactors. How the defects were not detected along the supply chain has not yet been disclosed. A commissioner from the NRA is to visitFrance to discuss the crisis.
From 1984-1993, JCFC also supplied steam generator components to the following Japanese reactors: Takahama 3&4, Sendai 2, Tomari 1&2 and Tsuruga 2. JCFC steam generator and reactor pressure vessel components are installed in a total of 14 Japanese reactors (not including two reactors at Fukushima Daiini).
• The French nuclear safety regulator has been investigating components supplied by both JCFC and the Japan Steel Works. Test results obtained by Greenpeace in June 2016 indicated that there was a possibility of excess carbon problem in JSW-manufactured components in the steam generator boiler pods – there are 3 or 4 steam generators in each pressurised water reactor PWR nuclear power plant, each weighs upwards of 300 to 400 tonnes and, typically, the cost of replacement is around US$130 to 150 million.