05000387/FIN-2011005-03
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Finding | |
|---|---|
| Title | Inadequate Post-Modification Testing Results in Main Turbine Trip and Automatic Scram |
| Description | A self-revealing finding of very low safety significance (Green) was identified when PPL personnel did not have adequate procedures to perform post-modification testing on the unit 2 digital integrated control system (ICS). Specifically, scheme checks and functional testing failed to identify an improper termination in the high reactor water level main turbine trip circuit. This error reduced the channel trip circuitry from a two-out-of-three logic to allowing a main turbine trip from a single channel. As a result, on August 19, 2011, during the first implementation of quarterly surveillance testing for the trip function following ICS and extended power uprate implementation, a main turbine trip and automatic reactor scram occurred. The performance deficiency was determined to be more than minor because the finding was associated with the Initiating Events cornerstone attribute of Equipment Performance, and affected the cornerstone objective of limiting the likelihood of those events that upset plant stability and challenged critical safety functions during power operation. Specifically, inadequate post-modification testing failed to identify an improperly terminated jumper which ultimately led to a main turbine trip and automatic reactor scram during subsequent surveillance testing. The inspectors evaluated the finding using IMC 0609, Attachment 4, Initial Screening and Characterization of Findings, and determined the finding did not contribute to both the likelihood of a reactor trip and the likelihood that mitigation equipment or functions would not be available. Consequently, the finding is of very low safety significance (Green). This finding is related to the CCA of Human Performance Resources because PPL did not ensure that personnel, equipment, procedures, and other resources were available and adequate to assure nuclear safety. Specifically, PPL did not ensure that complete, accurate and up-to-date maintenance and test procedures were available to perform post-modification testing on the digital ICS. |
| Site: | Susquehanna  |
|---|---|
| Report | IR 05000387/2011005 Section 4OA3 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | A Rosebrook C Crisden D Schroeder E Miller J Furia J Greives J Noggle K Modes P Finney P Krohn R Fuhrmeister S Ibarrola T Fish W Schmidt |
| CCA | H.7, Documentation |
| INPO aspect | WP.3 |
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Finding - Susquehanna - IR 05000387/2011005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Susquehanna) @ 2011Q4
Self-Identified List (Susquehanna)
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