ENS 46358
ENS Event | |
|---|---|
16:34 Oct 24, 2010 | |
| Title | 'A' Train Rhr Inoperable Due to Temperature Switch Failure on 'A' Control Room Chiller |
| Event Description | On 10/24/2010, while in Mode 5 in natural circulation cooling and no fuel movement in progress, the 'A' Control Room Chiller (AK400) tripped apparently due to an equipment failure of a temperature switch. This system was providing cooling for the Safety Auxiliaries Cooling System (SACS) room coolers. This caused the 'A' train of SACS and 'A' Train of Residual Heat Removal (RHR) to be administratively declared inoperable with the remaining train out of service for maintenance. As a result of the inoperable systems, the ability to remove residual heat could have been prevented. The 'A' RHR train, the alternate 'C' RHR train and the 'A' SACS Loop remained continuously available. No personnel were injured.
The licensee is in Technical Specification 3.9.11.1 Shutdown Cooling and 3.8.1.2 for SACS inoperable. The Emergency Diesel Generators (EDG) are available but inoperable as a result of SACS being inoperable. Offsite power is not affected and plant risk remains 'Green'. There were no significant events on-going at the time of the event. The licensee is bench testing a replacement switch at this time, and the chiller has been returned to service. The licensee is maintaining natural circulation and ensuring the availability of redundant RHR once a shift. The NRC Resident Inspector and Lower Alloyways Township have been notified.
Licensee is retracting this event based on the following: Hope Creek Technical Specification 3.9.11 action statement (a) for no OPERABLE RHR loops is to demonstrate the operability of at least one alternate method of decay heat removal within one hour and once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter. Prior to and throughout the event, decay heat, removal was maintained via the Fuel Pooling Cooling system through the available heat exchangers with core circulation maintained by natural circulation. Use of the Fuel Pool Cooling for decay heat removal is recognized in station procedures as an alternate method of decay heat removal in technical specification action statement (TSAS) 3.9.11. This retraction is to clarify that the inoperable systems did not prevent the ability to remove residual heat. The outage risk assessment remained Green throughout the period that both RHR loops were inoperable. There was no loss of safety function, and therefore, the event is not reportable as an event that prevents the fulfillment of a safety function in accordance with 50.72 (b)(3)(v)(B). Notified the R1DO (Daniel Holody) |
| Where | |
|---|---|
Hope Creek  New Jersey (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+0.75 h0.0313 days <br />0.00446 weeks <br />0.00103 months <br />) | |
| Opened: | Jim Kepley 17:19 Oct 24, 2010 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Dec 17, 2010 |
| 46358 - NRC Website
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WEEKMONTHYEARENS 463582010-10-24T16:34:00024 October 2010 16:34:00
[Table view]10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 'A' Train Rhr Inoperable Due to Temperature Switch Failure on 'A' Control Room Chiller 2010-10-24T16:34:00 | |