ENS 41037
ENS Event | |
|---|---|
19:55 Sep 12, 2004 | |
| Title | Both Trains of Reactor Building Spray Inoperable for Three Minutes |
| Event Description | The following information was obtained from the licensee via facsimile:
With the 1A Reactor Building Spray (RBS) train declared inoperable, due to an inoperable ES [Engineered Safeguards] digital channel, the suction valve to the 1B RBS train was stroked closed, rendering the 1B RBS train inoperable, concurrent with the 1A RBS train inoperability. The duration of the valve stroke, and dual RBS train inoperability was 3 minutes. This dual RBS train inoperability resulted in entry into TS [Technical Specification] 3.0.3 for the 3 minute duration of the valve stroke. At the time of this event, all three Reactor Building Cooling Unit (RBCU) trains were operable. The RBCUs provide a redundant, post-accident, containment heat removal function to the RBS trains. However, the RBS system is credited with post-accident iodine removal for the maximum hypothetical accident. Additionally, should an Engineered Safeguards actuation have occurred during the 3 minute stroke time, the RBS pumps in the 1B train would have started without the suction valve being fully open. This degraded suction flow could have impacted proper RBS pump operation in the event of an ES actuation. The 1B RBS train suction valve stroke was completed before it was noted that the valve stroke had resulted in the inoperability of the 1B RBS train, concurrent with the inoperability of the 1A RBS train. The 1B RBS train suction valve has been returned to an open condition and the 1B RBS train is currently operable. The operations personnel were performing valve stroke time surveillances when the event occurred. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| LER: | 05000269/LER-2004-003 |
| Time - Person (Reporting Time:+-0.68 h-0.0283 days <br />-0.00405 weeks <br />-9.31464e-4 months <br />) | |
| Opened: | Noel Clarkson 19:14 Sep 12, 2004 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Sep 12, 2004 |
| 41037 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |