ENS 46302
ENS Event | |
|---|---|
17:25 Oct 1, 2010 | |
| Title | Unanalyzed Condition - Appendix R Non-Compliance Issue Identified |
| Event Description | At 1325 EDT on October 1, 2010, an Appendix R non-compliance issue was identified associated with a potential loss of safety related 2400 VAC Bus 1C and 1D due to specifically sequenced fires affecting control cables and power cables routed in common fire areas but different raceways. An extent of condition corrective action identified that three 2400 VAC breakers 152-103 (Bus 1 C Service Water Pump P-7B), 152-205 (Bus 1D Service Water Pump P-7C), and 152-208 (Bus 1D Component Cooling Water Pump P-52B) all have control cables routed in the same fire areas as the associated power cables.
There are three fire areas, the 1C switchgear room 116A (Fire Area 4), screen house room 136 (Fire Area 9), and component cooling water room 123 (Fire Area16) that contain both control cables and power cables for the associated breakers. The concern is that a fire could first damage the control cable(s), resulting in the opening of the control power fuses which would disable the control power and render the breaker protection circuitry nonfunctional. The 2400 VAC breakers fail-as-is on loss of control power. As such if the breakers were closed they would remain closed until manually opened. If the same fire then damaged the power cable(s) on the same breaker, the loss of the breaker protection circuitry would prevent the individual breaker from automatically opening and the clearing of the cable fault would propagate upstream to the next coordinated breaker which would result in the associated 2400 VAC bus feeder breaker opening and a loss of the entire bus. Breaker 152-103 has the issue of both control and power cables present in the screen house room 136 (Fire Area 9) which has potential to result in the loss of the 1C bus for a fire in the screen house. The Appendix R safe shutdown analysis credits both 1C and 1D busses remaining available for a fire in Fire Area 9 and credits 1D bus remaining available for a fire in Fire Area 4. Breaker 152-205 has the issue of both control and power cables present in the screen house room 136 (Fire Area 9) and in the 1C Switchgear room 116A (Fire Area 4) which has potential to result in the loss of 1C and 1D busses for a fire in the screen house or the 1C switchgear room. The Appendix R safe shutdown analysis credits both 1C and 1D busses remaining available for a fire in Fire Area 9 and credits 1D bus remaining available for a fire in Fire Area 4. Breaker 152-208 has the issue of both control and power cables present in the component cooling water room 123 (Fire Area 16) which has the potential to result in the loss of 1D bus for a fire in the component cooling water room. The Appendix R safe shutdown analysis credits both 1C and 1D busses remaining available for a fire in Fire Area 16. The 1C and 1D busses are relied on to provide power to safety related equipment. The busses are normally supplied by offsite power. In the event that offsite power is lost, power is supplied to the busses by the emergency diesel generators. Existing hourly fire tours of the 1C switchgear room, the screen house room, and the component cooling water room are credited as initial compensatory measures. As a compensatory measure, existing hourly fire tours of the 1C switchgear room, the screen house room, and the component cooling water room are credited. This is considered to be an unanalyzed condition that significantly degrades plant safety. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Palisades  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-1.9 h-0.0792 days <br />-0.0113 weeks <br />-0.0026 months <br />) | |
| Opened: | Jeff Erickson 15:31 Oct 1, 2010 |
| NRC Officer: | Eric Simpson |
| Last Updated: | Oct 1, 2010 |
| 46302 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (92 %) |
| After | Power Operation (92 %) |
WEEKMONTHYEARENS 526472017-03-29T19:08:00029 March 2017 19:08:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 495162013-11-07T20:52:0007 November 2013 20:52:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 473222011-09-26T10:02:00026 September 2011 10:02:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Appendix R Equipment May Not Have Been Available ENS 463022010-10-01T17:25:0001 October 2010 17:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Appendix R Non-Compliance Issue Identified ENS 429592006-11-02T19:36:0002 November 2006 19:36:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition High Pressure Safety Injection (Hpsi) Pumps Alignment Blocks Improperly Installed ENS 423372006-02-14T21:00:00014 February 2006 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Appendix "R" Related Unanalyzed Condition 2017-03-29T19:08:00 | |