05000346/FIN-2012005-01
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Finding | |
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| Title | Operator Error in Response to a Small Power Transient Momentarily Renders TS Equipment Inoperable |
| Description | A self-revealed finding of very low safety significance and an associated NCV of Technical Specification (TS) 5.4.1(a) were identified following the control room crews response to a small power rise that occurred while shifting the plants Integrated Control System (ICS) to the track mode of operation on October 24, 2012. Specifically, the Unit Supervisor, a licensed senior reactor operator (SRO), directed an on-shift reactor operator (RO) to place the Steam Generator/Reactor Demand control station for the ICS in manual and lower power in response to the observed reactor power increase. However, because the plants control rod drive (CRD) control station (known as the Diamond panel) was already in manual as part of the planned ICS transfer to track mode, the signal from the Steam Generator/Reactor Demand control station only was passed through to the Feedwater (FW) System and not to the CRD System. As a result, average coolant temperature and pressurizer level both rose due to a mismatch between reactor power and steam generator power and caused an unplanned short-duration entry into TS Limiting Condition for Operation (LCO) 3.4.9, Condition A, for pressurizer level above the TS limit of 228 inches. The condition was corrected and corrective action program documents generated to review the event. This finding was associated with the Initiating Events Cornerstone of reactor safety and was of more than minor significance because it directly impacted the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. The inspectors reviewed this finding using the guidance contained in Appendix B, Issue Screening, of IMC 0612, Power Reactor Inspection Reports. The inspectors determined that the licensees incorrect actions in attempting to respond to the power transient by taking the Steam Generator/Reactor Demand control station for the ICS to manual and attempting to reduce power using that station with the Diamond panel in manual was a performance deficiency that was reasonably within the licensees ability to foresee and correct and should have been prevented. The finding screened as very low safety significance (Green) because it did not adversely impact any of the following parameters: Loss-of-Coolant Accident initiators; Transient initiators; Support System Loss initiators; Steam Generator Tube Rupture initiators; or External Event Initiators. The finding had a cross-cutting aspect in the area of problem identification and resolution, corrective action program (CAP) component, because the licensee failed to take corrective action for the ICS/Unit Load Demand (ULD) power error anomaly in a timely manner, commensurate with the issues safety significance and complexity. |
| Site: | Davis Besse  |
|---|---|
| Report | IR 05000346/2012005 Section 1R11 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.11 |
| Inspectors (proximate) | A Dunlop A Wilson D Kimble D Reeser J Cameron J Laughlin L Jones M Phalen P Smagacz R Walton T Briley |
| CCA | P.3, Resolution |
| INPO aspect | PI.3 |
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Finding - Davis Besse - IR 05000346/2012005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Davis Besse) @ 2012Q4
Self-Identified List (Davis Besse)
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