ENS 43450
ENS Event | |
|---|---|
03:39 May 2, 2007 | |
| Title | Invalid System Actuation |
| 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 May 1, 2007, at approximately 2339 hours0.0271 days <br />0.65 hours <br />0.00387 weeks <br />8.899895e-4 months <br /> (EDT), with H. B. Robinson Steam Electric Plant (HBRSEP), Unit No. 2, in MODE 5 with reactor coolant system temperature at approximately 84 degrees F, during activities associated with surveillance testing as part of Refueling Outage 24, the Train A EDG automatically started from the standby condition. The Train A 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 the inadvertent grounding of a test connection lead that was being used to monitor the Train A EDG during testing. The grounding of the test lead resulted in a drop in voltage on the starting circuitry that caused the actuation of the 4A diesel start relay. The Train A EDG successfully started and achieved the required speed and voltage. As previously stated, the EDG did not load because no UV signal was present on the associated E-1 bus. No failures or abnormalities were noted. The Train B EDG remained operable during this event and the Train A EDG was able to provide power to E-1 emergency bus, if necessary. The invalid EDG start event 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 improper isolation of a safety significant power source from the field installed equipment. The Plant Nuclear Safety Committee has reviewed the investigation associated with this reportable event and concurred with the investigation. Corrective actions for this event are in progress and are being tracked via the corrective action program." The licensee informed the NRC Resident Inspector. |
| Where | |
|---|---|
Robinson  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1353.28 h56.387 days <br />8.055 weeks <br />1.854 months <br />) | |
| Opened: | Curtis Castell 12:56 Jun 27, 2007 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Jun 27, 2007 |
| 43450 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 550792020-12-01T14:46:0001 December 2020 14:46:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-DAY Optional Telephonic Notification of an Invalid Specified System Actuation ENS 461272010-05-25T17:14:00025 May 2010 17:14:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Report for Inadvertent Safety Injection System Actuation ENS 434502007-05-02T03:39:0002 May 2007 03:39:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation ENS 420842005-08-31T22:05:00031 August 2005 22:05:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of an Emergency Diesel Generator 2020-12-01T14:46:00 | |