ENS 43106
ENS Event | |
|---|---|
22:00 Jan 18, 2007 | |
| Title | Battery Charger Room Cooler Inoperable |
| Event Description | Entered a condition which required TS 3.0.3 entry and an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report. While the 2B RHR equipment outage was in progress, it was discovered that the 2A Battery Charger room cooler was not operating. The condition was investigated and it was found that the thermal overloads were tripped on the supply breaker. They were reset and the fan was restarted. The shift observed the fan operation for 10 minutes and then decided to check the breaker every 30 minutes until a plan could be implemented to swap trains of battery chargers. During the first 30 minute check, the breaker overloads were found tripped again. See time line below.
This put us in a condition where an LOSF existed on both trains of RHR due to the requirement to evaluate supported systems when opposite train LCO's are entered. 02:00 2B RHR tagged out for equipment outage, entered LCO for RHR. 16:00 2A Battery Charger room cooler found not running. Entered LCO for DC sources. 16:35 Overloads reset on 2A Battery Charger room cooler supply breaker and fan restarted. LCO initially cleared, but now will conservatively be reinstated since the overloads tripped again later. 17:02 2A Battery Charger room cooler breaker thermal overloads found tripped again. 17:26 2B RHR tagged in and made available, but not yet operable (still need to perform surveillance), 17:37 Swing Battery Charger (2C) placed in service for 2A. Exited LCO for DC sources. LCO 3.0.3 was applicable from 16:00 until 17:37. Condition is reportable under 10CFR50.72(b)(3)(v) 'Event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat.' The licensee notified the NRC Resident Inspector.
The eight hour report (EN #43106) per 10 CFR 50.72(b)(3)(v)(b) was conservatively reported based on inconsistent operation of non-TS [Technical Specification] attendant equipment (the room cooler supplying cooling to the A-Train Battery charger) leading to the declaration of the battery charger as inoperable. However, no actual loss of safety function existed for the Unit 2 RHR Subsystem. Therefore, the eight hour report is retracted for the following reasons: The A-train DC battery was operable, and the A-train DC Battery Charger and DC bus were available. Procedures and training are in place for the door between the battery charger rooms to be opened to ensure sufficient cooling to the A train DC switchgear room. The time for room temperature heat-up allows for operator actions and the rooms and entry/exit pathways are accessible for operators to perform these actions during normal operations and design basis events. The battery charger room temperature was 86F upon discovery which is well within the equipment capability. Therefore, the battery charger room cooler system was available to provide cooling for the long term design basis accident. Technical specification 3.5.2, Condition A was entered due to the Unit 2 B-Train RHR pump scheduled equipment outage. During the entire time that the Unit 2 B-Train RHR pump was inoperable and out of service, the Unit 2 A-Train RHR pump would have performed its required function to supply sufficient flow during an accident (it was declared inoperable due to an inoperable DC support system, but remained available). Condition A allows one or more ECCS trains to be inoperable provided that 'at least 100% of the ECCS flow equivalent to a single OPERABLE ECCS train' is available. Even with the battery charger room cooler non-functional, the A-Train RHR pump would have performed its safety function and combined with the A-Train charging pump, would have delivered 100% of the ECCS flow equivalent to a single OPERABLE ECCS train. In summary, a loss of safety function on both trains of RHR did not exist and the 50.72(b)(3)(v)(b) report (EN # 43106) is retracted. Notified R2DO (HAAG). The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Farley  Alabama (NRC Region 2) | |
| Reporting | |
| 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: | Charles Barefield 21:08 Jan 18, 2007 |
| NRC Officer: | John Knoke |
| Last Updated: | Jan 22, 2007 |
| 43106 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 458122010-04-04T17:45:0004 April 2010 17:45:00
[Table view]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 Both Trains of Residual Heat Removal (Rhr) Inoperable ENS 441422008-04-15T13:49:00015 April 2008 13:49:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Residual Heat Removal System Declared Inoperable ENS 431062007-01-18T22:00:00018 January 2007 22:00:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Battery Charger Room Cooler Inoperable 2010-04-04T17:45:00 | |