ENS 47094: Difference between revisions
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| event date = 06/03/2011 00:39 EDT | | event date = 06/03/2011 00:39 EDT | ||
| last update date = 07/26/2011 | | last update date = 07/26/2011 | ||
| title = Invalid Actuation | | title = Invalid Actuation of Emergency Diesel Generator | ||
| event text = This report is being made per paragraphs 50.73(a)(1) and 50.73(a)(2)(iv)(A) to address an actuation of Emergency Diesel Generator 'A' on June 3rd, 2011 while performing service water valve isolation signal testing. Emergency AC Electrical power system, including emergency diesel generators, is a system named in 50.73(a)(2)(iv)(B). | | event text = This report is being made per paragraphs 50.73(a)(1) and 50.73(a)(2)(iv)(A) to address an actuation of Emergency Diesel Generator 'A' on June 3rd, 2011 while performing service water valve isolation signal testing. Emergency AC Electrical power system, including emergency diesel generators, is a system named in 50.73(a)(2)(iv)(B). | ||
During a refueling outage, testing was in progress to verify that service water isolation valves received the proper close signal during a safety injection. The test configuration required pulling control power fuses for the Bus 14 normal supply breaker to prevent operation and allow for manual relay actuation. Within seconds of pulling these fuses, the control room received a Bus 14 undervoltage annunciator, Emergency Diesel Generator 'A' started, and the generator output breaker closed onto Bus 14. Upon further investigation, the cause of this signal was identified as a degraded control relay that failed to mechanically latch and unexpectedly changed state when control power was removed. This resulted in an invalid undervoltage signal. Bus voltage remained within normal operating range. Given that the diesel generator was in unit mode of operation and was not fully synchronized with the normal bus supply, the diesel generator tripped shortly after starting due to a valid reverse power signal. A field verification and technical review was performed to ensure that this condition did not cause significant stress on the generator or engine. | During a refueling outage, testing was in progress to verify that service water isolation valves received the proper close signal during a safety injection. The test configuration required pulling control power fuses for the Bus 14 normal supply breaker to prevent operation and allow for manual relay actuation. Within seconds of pulling these fuses, the control room received a Bus 14 undervoltage annunciator, Emergency Diesel Generator 'A' started, and the generator output breaker closed onto Bus 14. Upon further investigation, the cause of this signal was identified as a degraded control relay that failed to mechanically latch and unexpectedly changed state when control power was removed. This resulted in an invalid undervoltage signal. Bus voltage remained within normal operating range. Given that the diesel generator was in unit mode of operation and was not fully synchronized with the normal bus supply, the diesel generator tripped shortly after starting due to a valid reverse power signal. A field verification and technical review was performed to ensure that this condition did not cause significant stress on the generator or engine. | ||
Latest revision as of 22:06, 1 March 2018
| Where | |
|---|---|
Ginna  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1279.58 h53.316 days <br />7.617 weeks <br />1.753 months <br />) | |
| Opened: | Mike Slaby 12:14 Jul 26, 2011 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jul 26, 2011 |
| 47094 - NRC Website
| |