ENS 41886
ENS Event | |
|---|---|
13:40 Aug 2, 2005 | |
| Title | Eccs Systems Inoperable Due to Excessive Reactor Equipment Cooling System Leakage |
| Event Description | This notification is being made pursuant to 50.72(b)(3)(v)[D- Accident Mitigation] as a loss of safety function due to unplanned inoperability of HPCI and both Low Pressure ECCS systems caused by inoperability of both REC subsystems.
At 08:40 CDT, Cooper Nuclear Station [CNS] declared both REC (Reactor Equipment Cooling) subsystems inoperable due to excessive leakage from REC system. CNS was in the process of tagging out the north east quad fan coil unit (FCU) for planned maintenance to replace an REC drain valve on the FCU. After commencing draining the FCU, the building operator noted excessive leakage at the drain. A check of REC system out-leakage determined that allowable REC leakage limits had been exceeded. Both REC subsystems were subsequently declared inoperable. REC is a support system for HPCI, RCIC, and all Low Pressure ECCS systems; therefore HPCI, RCIC, and all Low Pressure ECCS systems were declared inoperable. At 09:08, the REC drain valve was closed terminating the REC system leakage. REC, HPCI, RCIC, and all Low Pressure ECCS systems were subsequently declared operable. The licensee notified the NRC Resident Inspector.
This notification is being made to retract Event Notification 41886 that reported a loss of safety function due to the unplanned inoperability of HPCI and both Low Pressure ECCS systems caused by inoperability of both REC (Reactor Equipment Cooling) subsystems. Upon further evaluation, CNS determined that ECCS safety functions were not lost. The evaluation provided reasonable assurance that initiation of Service Water Backup system to ECCS area coolers would have maintained the ability of ECCS to perform their safety functions if the REC Surge Tank had reached its low level alarm. The licensee will notify the NRC Resident Inspector. The unit is operating at 100% / Mode 1. Notified R4DO (Spitzberg) |
| Where | |
|---|---|
Cooper  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.03 h0.0429 days <br />0.00613 weeks <br />0.00141 months <br />) | |
| Opened: | Steve Norris 14:42 Aug 2, 2005 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Sep 29, 2005 |
| 41886 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |