Nuclear regulators in Europe, US to caution against EPR piping

Thursday, April 8, 2010

Nuclear safety authorities in four countries are assessing the significance of undocumented welding on primary circuit piping for the EPR reactor under construction at Olkiluoto-3, Petteri Tiippana, director of the nuclear reactor regulation department at the Finnish Radiation and Nuclear Safety Authority STUK, told Platts in an interview Thursday.

But Tiippana said that contrary to a statement made Wednesday by Marie-Pierre Comets, a commissioner of French nuclear safety authority ASN, regulators from Finland, France, the UK and the US are not preparing a joint statement on the piping quality issue.

A spokesman for the UK Health and Safety Executive said that the HSE and the US Nuclear Regulatory Commission had observed a joint inspection of the piping made by the French company Nordon for the Olkiluoto-3 EPR. He said, "any action relating to this is for ASN and STUK, but we are not currently planning to issue a joint statement." HSE and the NRC are currently in the process of reviewing the "next-generation" EPR reactor design, but are not overseeing construction of EPR units, unlike STUK and ASN. The HSE spokesman said the piping quality is "not a design issue, it's a quality issue."

Olivier Gupta, ASN's director for power reactor regulation, said through a spokeswoman Thursday that "there will be no joint statement" on the piping issue. He said Comets had meant to refer to the "joint inspection" of the Nordon facilities by STUK and ASN, which was observed by representatives of NRC and HSE. The spokeswoman said Comets had "made a mistake."

The piping was manufactured by Nordon, a subcontractor to Areva, the French vendor which is supplying the nuclear part of the Olkiluoto-3 unit under a turnkey contract to utility Teollisuuden Voima Oy. Nordon, based in Nancy in eastern France, is a unit of the Fives group and has long been a major supplier of piping for nuclear power plants.

In October 2009, STUK found that small cracks in piping made for the main coolant lines of Olkiluoto-3 had been repaired with welding procedures that were not documented.

Tiippana said the piping is still in France and that analysis of the significance of the undocumented welding could be finished within several weeks. STUK will then do final inspections, probably before summer, he said. Until the piping is approved by STUK, it cannot be transported to Olkiluoto.

The main coolant lines for the EPR must be manufactured to very high quality standards and documentation must substantiate that quality, because the safety case for those high-pressure lines assumes they will not rupture suddenly.

In an unprecedented initiative, STUK, ASN and HSE issued a tripartite regulatory statement last November expressing concern about the instrumentation and control system architecture proposed for the EPR in their three countries.

Areva's 1,600- to 1,700 MW-class EPR reactor is under construction at Olkiluoto-3 in Finland and Flamanville-3 in France, and the design is under regulatory review for construction in the UK and the US.

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