Dominion's four Virginia nuclear units have reactor pressure vessels made by the same manufacturer that supplied a Belgian reactor shut down because of possible vessel cracking, a Dominion spokesman said Friday.
Dominion is following developments in Belgium, but has not been notified by the US Nuclear Regulatory Commission of any information related to the incident, Richard Zuercher said.
The NRC is sending a materials expert to a meeting in Belgium on the matter next week, agency spokesman Scott Burnell said Friday. It is too early to say whether NRC will impose additional requirements based on the Belgian incident.
The Belgium Federal Agency for Nuclear Control said Wednesday that possible cracking had been found at Electrabel's Doel-3 nuclear generating unit during a mandatory test of the vessel. The unit was ordered shut and regulators said it will remain down until at least the end of August.
Dutch company Rotterdam Dry Dock, which is no longer in business, manufactured the vessel for Doel-3 and an estimated 20 other units around the world, including reactors in Germany, the Netherlands, Spain, Sweden, Switzerland and the US, according to published reports this week. The type of cracking discovered at Doel-3 is associated with manufacturing issues, not with vessel aging, the Belgian regulator said Thursday.
Additional reactors in Belgium will be tested for the problem, the Federal Agency for Nuclear Control said.
The incident is being categorized on a preliminary basis as level 1 on the IAEA's International Nuclear Event Scale, which runs from 1 to 7, the Belgian regulator said. Depending on future information, that categorization could change, it said.
The reactor pressure vessel holds the core of nuclear fuel in reactors and is typically made of thick steel forgings and plates welded together.
"We have done multiple and extensive 10-year inservice inspections of our RPVs, as required by the NRC, and we have found no indication of any cracking," Dominion's Zuercher said in an email response. It appears four of Dominion's seven nuclear generating units -- North Anna-1 and -2 and Surry-1 and -2 -- all had RPVs manufactured by Rotterdam Dry Dock, he said.
Ringhals-2 in Sweden will be checked for vessel cracking when the unit shuts for annual maintenance in September, Ringhals management said in a statement Thursday. Swedish regulators said separately they are following developments at Doel-3 closely. Both the regulators and Ringhals management noted that no vessel cracking has previously been found at Ringhals-2.
Ingo Strube, a spokesman for Germany's environment ministry in Berlin, said Friday that none of the country's nine operating reactors are affected by the "anomalies" found at Doel-3. Strube said the ministry is checking on whether any of the eight reactors shut permanently in 2011 after the Fukushima I accident have the Rotterdam-supplied vessels.
Dutch utility EPZ said Thursday that Rotterdam manufactured part of the reactor vessel for its Borssele-1, but the use of different steel and components at that unit meant the situation at Doel-3 was "not the same" as at Borssele-1.