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| Entered date | Event description | |
|---|---|---|
| ENS 43984 | 13 February 2008 17:28:00 | On 1/30/08 at approximately 0617 Eastern Standard Time, while conducting a routine public warning siren interrogation test, the Harris Nuclear Plant (HNP) determined that the offsite emergency sirens were not capable of being activated. Initial investigations revealed that HNP lost power to the sirens due to a failure of the control module in the Uninterruptible Power Supply (UPS) of the siren system. At approximately 0644, an interrogation test of the system was completed and the sirens were verified to be operating normally. This event was initially viewed as not reportable. Subsequent investigation conducted between 1/31/08 and 2/13/08 revealed that other equipment supplied by the UPS was lost for between 70 and 80 minutes. As there is no direct monitoring capability for siren power supplies, it is reasonable to conclude that the sirens had been lost for a period of time between 70 and 80 minutes. This event should have been reported under 10 CFR 50.72(b)(3)(xiii) on 1/30/08. A completely new UPS system has been installed, and (the) siren systems are fully functional at this time. The UPS was replaced on 2/7/08. Its loss on 1/30/08 affected all 81 sirens. The NRC Resident Inspector will be notified. |