ENS 41370: Difference between revisions
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StriderTol (talk | contribs) (Created page by program invented by Mark Hawes) |
StriderTol (talk | contribs) (Created page by program invented by StriderTol) |
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| event date = 02/03/2005 19:15 CST | | event date = 02/03/2005 19:15 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 1915 hours, DNPS 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 Units. Although the CT is currently fully operable, failure of the CT circuitry will cause the neutral overcurrent relay to trip (and lockout) the main, reserve and tie feed breakers. These combined protective relay trips will act to trip and lock out the circuit breakers supplying feeds to buses 23 (33) and 24 (34), essentially isolating them from their normal and emergency power sources. Emergency power (i.e., the emergency diesel generator) would still be available to safety related buses 23-1 (33-1) and 24-1 (34-1), but the Containment Cooling Service Water (CCSW) system would remain without a power source. If this failure occurred during a LOCA, then the CCSW pumps may not be able to be started within ten minutes. 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 a degraded or unanalyzed condition (10CFR50.72(b)(3)(ii)(B)). | On February 3, 2005 at 1915 hours, DNPS 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 Units. Although the CT is currently fully operable, failure of the CT circuitry will cause the neutral overcurrent relay to trip (and lockout) the main, reserve and tie feed breakers. These combined protective relay trips will act to trip and lock out the circuit breakers supplying feeds to buses 23 (33) and 24 (34), essentially isolating them from their normal and emergency power sources. Emergency power (i.e., the emergency diesel generator) would still be available to safety related buses 23-1 (33-1) and 24-1 (34-1), but the Containment Cooling Service Water (CCSW) system would remain without a power source. If this failure occurred during a LOCA, then the CCSW pumps may not be able to be started within ten minutes. 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 a degraded or unanalyzed condition (10CFR50.72(b)(3)(ii)(B)). | ||
Latest revision as of 21:21, 1 March 2018
| Where | |
|---|---|
Dresden  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:+-0.87 h-0.0363 days <br />-0.00518 weeks <br />-0.00119 months <br />) | |
| Opened: | Paul Salgado 00:23 Feb 4, 2005 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Feb 4, 2005 |
| 41370 - NRC Website
| |
Dresden 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 | |