ENS 42084

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v t e ENS Event
22:05 Aug 31, 2005
Title	Invalid Actuation of an Emergency Diesel Generator
Event Description	This telephone notification to report an invalid actuation is provided in accordance with 10 CFR 50.73(a)(1), which states, 'In the case of an invalid actuation reported under Sec. 50.73(a)(2)(iv), other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER.' The specific reporting requirement in 10 CFR 50.73(a)(2)(iv)(A), states, 'Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B).' For this report, the affected system was the emergency AC electrical power systems as listed in 10 CFR 50.73(a)(2)(iv)(B)(8). Specifically, the Train A emergency diesel generator (EDG) automatically started due to an invalid system actuation. On August 31, 2005, at approximately 1805 hours0.0209 days <br />0.501 hours <br />0.00298 weeks <br />6.868025e-4 months <br /> (EDT), with H. B. Robinson Steam Electric Plant (HBRSEP), Unit No. 2, operating in MODE 1 at approximately 100% power, the Train A EDG automatically started from the standby condition. The EDG did not automatically connect to the associated emergency bus (E-1), because no E-1 bus undervoltage (UV) signal was present. The automatic start was caused by a failed solenoid-operated valve (SOV) in the air start system for the EDG (valve number DA-23A). The SOV failed-open, which is the designed failure-mode condition for this valve. This admitted air to the EDG air-start distributor, which started the Train A EDG. No additional failures or abnormalities were noted. The Train A EDG successfully started and achieved the required speed and voltage, but as stated previously, the EDG did not load because no UV signal was present on the associated bus. The Train B EDG remained operable during this event. Also, the EDGs each have two starting SOVs that are in parallel in the starting air system. A start signal or a loss of power to either valve is sufficient to start the associated EDG. The failed SOV was replaced. The Train A EDG was tested after replacement of the SOV and returned to service at 1016 hours0.0118 days <br />0.282 hours <br />0.00168 weeks <br />3.86588e-4 months <br /> on September 1, 2005. The invalid EDG start was entered into the corrective action program for HBRSEP, Unit No. 2. The investigation of this event has been completed. The results of the investigation determined that the EDG start was caused by a short-circuit failure of the coil for the SOV. Additional corrective actions for this condition, beyond replacement of the failed SOV, are in progress and are being tracked via the corrective action program. The licensee notified the NRC Resident Inspector.

ENS 42084 +/-
Where
Robinson South Carolina (NRC Region 2)
Reporting

10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation
Time - Person (Reporting Time:+1355.57 h56.482 days <br />8.069 weeks <br />1.857 months <br />)
Opened:	Curtis Castell 09:39 Oct 27, 2005
NRC Officer:	Bill Huffman
Last Updated:	Oct 27, 2005
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v • d • e

v t e Emergency Notification System
Robinson with 10 CFR 50.73(a)(1), Submit an LER
WEEKMONTHYEAR2020-12-01T14:46:00 [Table view]
[ENS list for Robinson]

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