ENS 49285
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ENS Event | |
|---|---|
20:10 Aug 15, 2013 | |
| Title | a Hot Short in the Rhr Shutdown Cooling Control Cable Could Result in an Inter-System Loca |
| Event Description | A condition was identified that resulted from an inter-cable circuit analysis as part of the safe shutdown analysis that identified a vulnerability associated with two Unit 2 valves with controls in Fire Area 2203. Specifically, during the postulated fire scenario, an inter-cable hot short could occur on the control cables for the RHR shutdown cooling suction valve 2E11-F008 valve and cause the valve to open in the event of a postulated fire in Fire Area 2203F which is in the vicinity of the Unit 2 remote shutdown panel. In addition, a spurious opening of RHR shutdown cooling suction valve 2E11-F009 valve could occur due to a hot short on the control cables. The fire is postulated while in Mode 1 which could cause both valves to open during power operation. This postulated event would expose the low pressure RHR-shutdown cooling suction line to normal operating pressures which would result in an inter-system LOCA.
Immediate actions were taken to de-energize the valves in the 'closed' position which removed the vulnerability. When this condition was first discovered, the consequences of this postulated condition were evaluated and there was reasonable assurance that the condition did not represent an unanalyzed condition that significantly degrades/degraded plant safety. A review of the FSAR, design documents and regulatory requirements was performed to document the foundational logic for the engineering judgment to support the original conclusion that there was reasonable assurance that the inter-system LOCA did not represent an unanalyzed condition that significantly degraded plant safety and that this would not result in a loss of a safety function. Based on information learned in this review there was not sufficient information to make a conclusive determination. Since a conclusive determination cannot be made at this time and since there is some doubt regarding whether or not the report is needed, this report is being made in accordance with 10CFR50.72(b)(3)(ii). The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Hatch  Georgia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-3.38 h-0.141 days <br />-0.0201 weeks <br />-0.00463 months <br />) | |
| Opened: | Kenny Hunter 16:47 Aug 15, 2013 |
| NRC Officer: | Dong Park |
| Last Updated: | Aug 15, 2013 |
| 49285 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 526502017-03-30T13:22:00030 March 2017 13:22:00
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