05000296/FIN-2015002-01
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Finding | |
|---|---|
| Title | Unit 3 HPCI Turbine Exhaust Drain High Level |
| Description | The inspectors identified an unresolved item (URI) associated with repeat observations of HPCI Turbine Exhaust Drain Pot High Level Alarms upon shutdown of the Unit 3 HPCI turbine. Information associated with the licensees cause determination, previous corrective actions, and design change documentation required for review of the HPCI Turbines final operability determination and disposition the issue was not available at the conclusion of the inspection period. The inspectors conducted a review of the implementation of corrective actions from related PERs 885945, 933630, and 999196 which were written due to repeat observations of HPCI Turbine Exhaust Drain Pot High Level Alarms upon shutdown of the Unit 3 HPCI turbine. The review revealed that the HPCI system was unknowingly in a degraded state and because the licensee did not effectively document all aspects of the problem, appropriate corrective actions and operability determinations were not completed in a timely manner. Specifically, the amount of water drained from the turbine casing was not recorded until the third occurrence, but even then, the amount was an estimation. Following questioning by the NRC inspectors, the licensee discovered that the severity of the problem had been underestimated and that the turbine exhaust vacuum breakers may not be adequately designed to prevent siphoning of suppression pool water back to the turbine casing. Ultimately, with engineering support from the system vendor, the licensee determined that the HPCI system remained operable despite the presence of approximately 190 gallons of water in the turbine casing. Because more information is necessary to properly evaluate the final operability determination, licensee actions, and system design, future inspection is required to determine if a more than minor performance deficiency or violation exists associated with this issue. Initial reviews have not identified any immediate safety concerns associated with the determination. This is identified as URI 05000296/2015002-01, HPCI Turbine Exhaust Drain High Level. |
| Site: | Browns Ferry  |
|---|---|
| Report | IR 05000296/2015002 Section 4OA2 |
| Date counted | Jun 30, 2015 (2015Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | A Blamey A Ruh D Dumbacher D Terry-Ward G Ottenberg J Seat R Baldwin R Williams T Stephena Blameya Ruh D Dumbacher J Montgomery M Singletary P Cooper R Hamilton R Kellner T Stephen W Pursley |
| INPO aspect | |
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Finding - Browns Ferry - IR 05000296/2015002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Browns Ferry) @ 2015Q2
Self-Identified List (Browns Ferry)
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