Areva reviews forging inspections
Areva announced yesterday that it is conducting additional studies on the quality of forged components and the quality processes at its Le Creusot facility in Burgundy. It plans an external review of areas related to forging and inspections.
The company said that analyses have been carried out on the fabrication of forgings for the reactor pressure vessel (RPV) of the EPR under construction at Flamanville. Analyses have also been made on studies previously conducted on other forgings, particularly as part of the establishment of revised mechanical specifications for nuclear pressure equipment introduced in 2005.
Areva said the analyses also concern a mechanical testing laboratory at Creusot where a tool for hot tensile testing was incorrectly used between 2009 and 2014. The company said the misused testing equipment "is not a technical problem for the manufactured components, but is a malfunction in the quality of inspection that requires a reinterpretation of results or to redo certain tests". It said that tests performed since have demonstrated that the results are "in compliance with requirements".
"These assessments have confirmed thus far the intrinsic quality of the forgings and the safety of components," Areva noted. However, it said the verification process is ongoing and will take several months to complete. "None of the components concerned with the inaccuracy of this inspection tool are installed in nuclear power plants in operation," the company added.
Areva plans to strengthen its internal quality control process with an external review of areas related to forging and inspections. The company intends to contract Lloyd's Register Apave Limited to conduct this review, which is scheduled to begin on 4 May and take at least two months to complete.
This review will help Areva identify the causes of potential defects in practices and in quality inspection, "as well as the measures to take to continue the improvements made since purchasing the forge in 2006", it said.
The upper and bottom head of the RPV for the Flamanville EPR were manufactured at Areva's Le Creusot facility in September 2006 and January 2007, respectively.
The French nuclear regulator, the ASN (Autorité de Sûreté Nucléaire), announced on 7 April it had been informed by Areva that chemical and mechanical tests conducted in late 2014 on an RPV head similar to that of the Flamanville EPR had revealed an area with high carbon concentration. This, it said, has led to "lower than expected mechanical toughness values".
EDF said earlier this week that work is continuing at the Flamanville construction site and that preparations are underway to conduct further tests on the unit's vessel.
Some of the RPV heads for the two EPR units under construction at Taishan, China, were also manufactured at Le Creusot using a process similar to that for the Flamanville EPR. However, those for the EPR being built at Olkiluoto in Finland were manufactured by another supplier.
Researched and written
by World Nuclear News
