Nuclear Event – North-America – USA


EDIS Number: NC-20120327-34670-USA
Date / time: 27/03/2012 03:30:15 [UTC]
Event: Nuclear Event
Area: North-America
Country: USA
State/County: State of Virginia
Location: [North Anna Nuclear Generating Station]
Number of Deads: N/A
Number of Injured: N/A
Number of Infected: N/A
Number of Missing: N/A
Number of Affected: N/A
Number of Evacuated: N/A
Damage level: N/A

Description:

Dominion power reported two events over the weekend at North Anna Power Station to the Nuclear Regulatory Commission. The first was the discovery of a problem with a pipe joint on a steam generator. Workers found cracks in the weld on a large pipe attached to one of the unit’s three steam generators. Steam generators convert heated water from the reactor to steam to drive the turbines, which produce electricity. The cracks were discovered during Unit 1’s refueling outage. New turbines are also being installed, so the outage is taking longer than the month or so it usually requires for refueling. Richard Zuercher, a spokesman for Dominion’s nuclear operations, said Monday that two small cracks were discovered at a weld point where pipes of two different types of steel were connected. That “degraded condition” was reported to the NRC. There was no danger to employees or the public, the company said. An engineering evaluation will be done, and corrective actions taken, according to the report. In the second NRC report, North Anna declared an “unusual event” after an earthquake aftershock late Sunday. Zuercher said a report is filed with the NRC if the tremor is felt in the control room. North Anna recently installed some additional monitoring equipment in response to last summer’s earthquake. An inspection was done after the magnitude-3.1 aftershock hit at 11:21 p.m. Sunday. No damage was discovered. Unit 2 continues to operate at full power. Before Sunday’s tremor, the last unusual event was declared after a magnitude-3.2 aftershock in January. There have been dozens of aftershocks in excess of magnitude 2.0 since the magnitude-5.8 earthquake last Aug. 23. The plant sits on the Louisa County shore of Lake Anna, about 11 miles from the earthquake’s epicenter near Mineral.

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