ENS 53128: Difference between revisions
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| emergency class = Non Emergency | | emergency class = Non Emergency | ||
| notification date = 12/19/2017 17:17 | | notification date = 12/19/2017 17:17 | ||
| retracted = Yes | |||
| notification by = Roy Giles | | notification by = Roy Giles | ||
| NRC officer = Vince Klco | | NRC officer = Vince Klco | ||
| event date = 12/19/2017 13:40 CST | | event date = 12/19/2017 13:40 CST | ||
| last update date = | | last update date = 02/14/2018 | ||
| title = Diesel Generators (Dgs) Declared Inoperable Due | | title = Diesel Generators (Dgs) Declared Inoperable Due to a Common Issue | ||
| event text = During regular power operations at 100% power, DG#1 and DG#2 were declared inoperable due to a common issue associated with indicating lights and the associated sockets installed in various control and auxiliary circuits for both DG's. | | event text = During regular power operations at 100% power, DG#1 and DG#2 were declared inoperable due to a common issue associated with indicating lights and the associated sockets installed in various control and auxiliary circuits for both DG's. | ||
The indicating lights in question are incandescent 120V AC style 120MB bulbs in a socket with a 550 ohm resistor. Style 120MB light bulbs have a failure mechanism where the bulb can cause a short circuit rather than the more common open circuit that is expected when an incandescent bulb filament fails. Cooper originally believed that the socket's integral resistor was sufficient to protect the circuit. In testing performed by an outside laboratory and confirmed on-site using warehouse stock, it was determined that the integral resistor may not have the power dissipation capability to protect the circuit ln which the light and socket are installed if a bulb fails in short circuit. | The indicating lights in question are incandescent 120V AC style 120MB bulbs in a socket with a 550 ohm resistor. Style 120MB light bulbs have a failure mechanism where the bulb can cause a short circuit rather than the more common open circuit that is expected when an incandescent bulb filament fails. Cooper originally believed that the socket's integral resistor was sufficient to protect the circuit. In testing performed by an outside laboratory and confirmed on-site using warehouse stock, it was determined that the integral resistor may not have the power dissipation capability to protect the circuit ln which the light and socket are installed if a bulb fails in short circuit. | ||
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As a result of both DG's being inoperable, the Control Room Emergency Filtration System is also inoperable. This is also a loss of safety function subject to an 8 hour report for the same criterion. | As a result of both DG's being inoperable, the Control Room Emergency Filtration System is also inoperable. This is also a loss of safety function subject to an 8 hour report for the same criterion. | ||
The Senior Resident has been notified. | The Senior Resident has been notified. | ||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/ | * * * RETRACTION AT 0942 EST ON 02/14/2018 FROM DAVID VAN DERKAMP TO JEFF HERRERA * * * | ||
CNS is retracting the 8-hour non-emergency notification made on December 19, 2017 at 1340 CST (EN# 53128). Subsequent evaluation concluded a postulated lamp short circuit failure in any of the affected circuits would not impact the ability of the Diesel Generators to perform their safety function and therefore, were operable. With DG operability not affected, the Control Room Emergency Filtration System also remained operable. | |||
The NRC Resident Inspector has been notified. | |||
Notified the R4DO (Werner). | |||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180215en.html#en53128 | |||
}}{{unit info | }}{{unit info | ||
| Unit = 1 | | Unit = 1 | ||
Latest revision as of 21:41, 1 March 2018
| Where | |
|---|---|
Cooper  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-2.38 h-0.0992 days <br />-0.0142 weeks <br />-0.00326 months <br />) | |
| Opened: | Roy Giles 17:17 Dec 19, 2017 |
| NRC Officer: | Vince Klco |
| Last Updated: | Feb 14, 2018 |
| 53128 - NRC Website
| |
Cooper with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |