ENS 41369: Difference between revisions
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StriderTol (talk | contribs) (Created page by program invented by StriderTol) |
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| event date = 02/03/2005 18:19 CST | | event date = 02/03/2005 18:19 CST | ||
| last update date = 02/04/2005 | | last update date = 02/04/2005 | ||
| title = 4160 Volt Relaying | | title = 4160 Volt Relaying and Metering Single Failure Vulnerability | ||
| event text = The licensee provided the following report via facsimile: | | event text = The licensee provided the following report via facsimile: | ||
On February 3, 2005 at 1819 hours, Quad Cities Nuclear Power Station (QCNPS) confirmed a vulnerability with a 4160 VAC relaying and metering current transformer (CT) associated with the Unit and Reserve Auxiliary Transformers (i.e., the UAT and RAT) on both Unit 1 and Unit 2. Although the CT is currently fully operable, failure of the CT circuitry could cause the neutral overcurrent relay to trip and lockout the circuit breakers supplying feeds to safety related buses 13 (23) and 14 (24), isolating them from their normal and emergency power sources. Emergency power (i.e., the emergency diesel generator) would still be available to supply power to safety related buses 13-1 (23-1) and 14-1 (24-1), but the Residual Heat Removal Service Water (RHRSW) system may be without a source of power. If this failure occurred during a LOCA, then the RHRSW pumps may not be started within the ten minute requirement. A modification is in progress to eliminate this vulnerability. This event is being reported as a potential loss of safety function (10CFR50.72(b)(3)(v)(B)) and as a degraded or unanalyzed condition (10CFR50.72(b)(3)(ii)(B)). | On February 3, 2005 at 1819 hours, Quad Cities Nuclear Power Station (QCNPS) confirmed a vulnerability with a 4160 VAC relaying and metering current transformer (CT) associated with the Unit and Reserve Auxiliary Transformers (i.e., the UAT and RAT) on both Unit 1 and Unit 2. Although the CT is currently fully operable, failure of the CT circuitry could cause the neutral overcurrent relay to trip and lockout the circuit breakers supplying feeds to safety related buses 13 (23) and 14 (24), isolating them from their normal and emergency power sources. Emergency power (i.e., the emergency diesel generator) would still be available to supply power to safety related buses 13-1 (23-1) and 14-1 (24-1), but the Residual Heat Removal Service Water (RHRSW) system may be without a source of power. If this failure occurred during a LOCA, then the RHRSW pumps may not be started within the ten minute requirement. A modification is in progress to eliminate this vulnerability. This event is being reported as a potential loss of safety function (10CFR50.72(b)(3)(v)(B)) and as a degraded or unanalyzed condition (10CFR50.72(b)(3)(ii)(B)). | ||
Latest revision as of 21:21, 1 March 2018
| Where | |
|---|---|
Quad Cities  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+-0.52 h-0.0217 days <br />-0.0031 weeks <br />-7.12296e-4 months <br />) | |
| Opened: | Terry Gallentine 23:48 Feb 3, 2005 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Feb 4, 2005 |
| 41369 - NRC Website
| |
Quad Cities with 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |