ENS 48467: 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 = 10/31/2012 12:53 CDT | | event date = 10/31/2012 12:53 CDT | ||
| last update date = 10/31/2012 | | last update date = 10/31/2012 | ||
| title = Potentially Unable | | title = Potentially Unable to Provide Power to Safe Shutdown Equipment During Appendix R Fire | ||
| event text = During BFNP [Browns Ferry Nuclear Plant] NFPA [National Fire Protection Association] 805 transition review, it was determined in the event of an Appendix R fire, the ability to provide power to equipment needed to achieve and maintain safe shutdown may be adversely impacted. In certain fire zones/areas, feeder breakers for the 480V Shutdown Boards are credited for backup control operation using the 43 emergency switches, which isolate the breaker controls from circuits going to the control bay, and allow for local operation of the breaker. Fire damage to Main Control Room 480V Shutdown Board transfer switch cables could cause the control circuit fuses for the credited breaker to clear prior to the use of the 43 emergency switch. In addition, cable fire damage in the same fire areas could also cause the normal and/or alternate feeder breakers to spuriously trip. These breakers do not have separate emergency fuses like other BFNP breakers equipped with backup controls. Therefore, Safe Shutdown Instruction (SSI) procedure steps to use 43 switches to perform local breaker operation to supply power to safe shutdown equipment may not work as written where this cable fire damage can occur. | | event text = During BFNP [Browns Ferry Nuclear Plant] NFPA [National Fire Protection Association] 805 transition review, it was determined in the event of an Appendix R fire, the ability to provide power to equipment needed to achieve and maintain safe shutdown may be adversely impacted. In certain fire zones/areas, feeder breakers for the 480V Shutdown Boards are credited for backup control operation using the 43 emergency switches, which isolate the breaker controls from circuits going to the control bay, and allow for local operation of the breaker. Fire damage to Main Control Room 480V Shutdown Board transfer switch cables could cause the control circuit fuses for the credited breaker to clear prior to the use of the 43 emergency switch. In addition, cable fire damage in the same fire areas could also cause the normal and/or alternate feeder breakers to spuriously trip. These breakers do not have separate emergency fuses like other BFNP breakers equipped with backup controls. Therefore, Safe Shutdown Instruction (SSI) procedure steps to use 43 switches to perform local breaker operation to supply power to safe shutdown equipment may not work as written where this cable fire damage can occur. | ||
Compensatory actions in the form of fire watches to mitigate this condition are in place in accordance with the BFNP Fire Protection Report. | Compensatory actions in the form of fire watches to mitigate this condition are in place in accordance with the BFNP Fire Protection Report. | ||
Latest revision as of 22:02, 1 March 2018
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 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)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+3.27 h0.136 days <br />0.0195 weeks <br />0.00448 months <br />) | |
| Opened: | William Ball 21:09 Oct 31, 2012 |
| NRC Officer: | John Knoke |
| Last Updated: | Oct 31, 2012 |
| 48467 - NRC Website
| |
Browns Ferry with 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)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |