The latest from NC WARN on the continuing Shearon Harris/Progress Energy story:
Tough Week for Progress Nuclear Plants
Monday: Sirens at Shearon Harris: All 81 emergency sirens in the Harris 10-mile emergency zone were reported to NRC as being inoperable for at least two hours. Progress Energy says the cause was failure of a device that signals the sirens via a communications tower. Progress said that in an emergency, operators could manually override the device and activate the sirens.
Tuesday: Harris siren system fails again – all sirens were inoperable for several hours due to the same equipment failure. The tower, located on the Owner Controlled Area, is apparently the same one that an intruder hung a large flag on a year ago, when Progress downplayed the tower's importance.
Wednesday: Emergency declared at Brunswick Unit II due to an “unusual event” caused by a transformer failure that caused loss of offsite power and primary cooling to the reactor, located south of Wilmington. Most safety systems responded correctly (two required operator help), including the emergency diesel generators.
Thursday: Brunswick Unit I powers down. When one of the emergency generators malfunctioned, the Unit I reactor was required by regulations to be powered down for 12 hours until another generator was connected to the backup cooling system.
NOTE: Although this week’s siren malfunctions apparently happened for a different reason, Harris and Brunswick have suffered multiple siren failures in recent years due to loss of power associated with severe weather – higher risk occasions when sirens could be needed. Sometimes a large number of sirens have been inoperable for many hours. Since mid-2005, Progress has been saying it plans to install backup power for the sirens. After a quarter of the Harris sirens failed in June, the company said it will be late 2007 before backup power is installed at the plant.