ENS 43157: Difference between revisions
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| event date = 02/08/2007 13:42 CST | | event date = 02/08/2007 13:42 CST | ||
| last update date = 03/15/2007 | | last update date = 03/15/2007 | ||
| title = Raw Water Pumps Declared Inoperable Due | | title = Raw Water Pumps Declared Inoperable Due to a Potential Failure of the Pump Breaker Linkages | ||
| event text = On February 8, 2007 at 10:22 CST, Raw Water Pump AC-10C was declared inoperable when the pump breaker experienced a plunger linkage failure during a scheduled pump start for a scheduled rotation. Due to a similar failure of Raw Water Pump AC-10B two weeks earlier, a condition report was initiated for engineering to review the potential for a common failure mode. Engineering reviewed the number of cycles of the breakers for AC-10A and AC-10D both have greater than 1600 cycles. The breaker for AC-10B had over 1200 cycles at the time of its failure and AC-10C was over 1700 cycles. Based on the similar numbers of cycles, engineering has determined that continued operation of AC-10A and AC-10D without breaker failure could not he assured. All other safeguards associated breakers have been verified to have less than 1000 cycles and are not considered to be susceptible to breaker failure at this time. After discussion with engineering, Raw Water Pumps AC-10A and AC-10D were declared inoperable on February 8, 2007 at 13:42 CST based on the number of breaker cycles for these two components in relation to the two breakers that failed. | | event text = On February 8, 2007 at 10:22 CST, Raw Water Pump AC-10C was declared inoperable when the pump breaker experienced a plunger linkage failure during a scheduled pump start for a scheduled rotation. Due to a similar failure of Raw Water Pump AC-10B two weeks earlier, a condition report was initiated for engineering to review the potential for a common failure mode. Engineering reviewed the number of cycles of the breakers for AC-10A and AC-10D both have greater than 1600 cycles. The breaker for AC-10B had over 1200 cycles at the time of its failure and AC-10C was over 1700 cycles. Based on the similar numbers of cycles, engineering has determined that continued operation of AC-10A and AC-10D without breaker failure could not he assured. All other safeguards associated breakers have been verified to have less than 1000 cycles and are not considered to be susceptible to breaker failure at this time. After discussion with engineering, Raw Water Pumps AC-10A and AC-10D were declared inoperable on February 8, 2007 at 13:42 CST based on the number of breaker cycles for these two components in relation to the two breakers that failed. | ||
With three Raw Water Pumps inoperable, Fort Calhoun Station entered Technical Specification 2.0.1 which requires the plant be placed in hot shutdown within six (6) hours. The potential for a common mode failure of the linkage in the 4160 VAC circuit breakers (ABB Combustion Engineering Model No. 5VKBR-250) could have prevented operation of the Raw Water Pumps to fulfill the required design function to remove residual heat during a design basis accident. | With three Raw Water Pumps inoperable, Fort Calhoun Station entered Technical Specification 2.0.1 which requires the plant be placed in hot shutdown within six (6) hours. The potential for a common mode failure of the linkage in the 4160 VAC circuit breakers (ABB Combustion Engineering Model No. 5VKBR-250) could have prevented operation of the Raw Water Pumps to fulfill the required design function to remove residual heat during a design basis accident. | ||
Latest revision as of 21:17, 1 March 2018
| Where | |
|---|---|
Ft Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+-1.03 h-0.0429 days <br />-0.00613 weeks <br />-0.00141 months <br />) | |
| Opened: | Erick Matzke 18:40 Feb 8, 2007 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Mar 15, 2007 |
| 43157 - NRC Website
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