05000482/FIN-2012009-01
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Finding | |
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| Title | Failure to Follow Procedures on Contractor Control During Maintenance on the Startup Transformer |
| Description | The team reviewed a self-revealing apparent violation of Technical Specification 5.4.1.a and Regulatory Guide 1.33 for the failure to follow procedures. Specifically, the electrical penetration seal and wiring assembly associated with the H1/CT4 and H2/CT5 current transformers installed in the startup transformer (XMR01) were replaced without insulating two of the splices, as required by Work Order 11-240360-006, Revision 3. This affected safety-related equipment on January 13, 2012, when the startup transformer experienced a spurious trip and lockout during a plant trip because the two uninsulated wires touched and provided a false high phase differential signal to the protective relaying circuit. The protective lockout caused a prolonged loss of offsite power to Train B equipment. The licensees root cause analysis concluded that the Startup Transformer failure on January 13, 2012, was caused by the failure to provide adequate oversight of contractors. As a result, the licensee failed to identify that electrical maintenance contractors had failed to install insulating sleeves on two wires that affected the differential current protection circuit. This issue was entered into the corrective action program as Condition Report 47653. The licensees corrective actions included reworking the current transformer junction block to correct the missing insulation sleeves and updating station procedures to require oversight of contractors performing work on risk significant components. This finding was more than minor because it affected the human performance attribute of the Initiating Events Cornerstone and affected the cornerstone objective of limiting the likelihood of those events that upset plant stability and challenge critical safety functions. This deficiency resulted in the failure of the fast bus transfer and the failure to maintain offsite power to safety-related loads during a reactor/turbine trip. The team performed the significance determination using NRC Inspection Manual Chapter 0609, Attachment 0609.04, Phase 1 Initial Screening and Characterization of Findings, dated January 10, 2008, because it affected the Initiating Events Cornerstone while the plant was at power. The Phase 1 screened to a Phase 3 because the finding contributed to both the likelihood of a reactor trip and the likelihood that mitigation equipment would not be available. A Senior Reactor Analyst performed a Phase 3 analysis using the Wolf Creek SPAR model, Revision 8.20. The performance deficiency was determined to impact all transient sequences, particularly those involving losses of essential service water and/or component cooling water that led to a reactor coolant pump seal loss of coolant accident. The loss of cooling water prevented successful room cooling for mitigation equipment as well as loss of containment recirculation phase cooling. The analyst used half (98.5 days) of the period since the last successful load transfer, since the actual time of failure could not be determined from the available information. Credit for recovery of limited non-vital loads on the startup transformer was given based on licensee troubleshooting results; however no recovery credit was available for room cooling, since the licensee had no preplanned alternate room cooling measures. The evaluation of external events showed a small contribution due to fires. The change in the core damage frequency (delta-CDF) was determined to be 2.59E-5. Therefore, this finding was preliminarily determined to have substantial safety significance (Yellow). The change in large early release frequency (delta-LERF) was 1.62E-7. This value for delta-LERF would result in a finding of low to moderate safety significance (White). However, this is a bounded by the preliminary yellow safety significance resulting from the delta CDF calculation. This finding had a human performance cross-cutting aspect associated with the work control component in that licensee personnel associated with the oversight of the work did not appropriately coordinate work activities, and address the impact of changes to the work scope consistent with nuclear safety |
| Site: | Wolf Creek  |
|---|---|
| Report | IR 05000482/2012009 Section 4OA5 |
| Date counted | Sep 30, 2012 (2012Q3) |
| Type: | Violation: Yellow |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 93800 |
| Inspectors (proximate) | G Replogle J Dixon J Watkins M Baquera M Runyan N O'Keefe N Okonkwoc Osterholtzc Young E Ruesch E Uribe M Bloodgood N O'Keefe T Hartman |
| Violation of: | Technical Specification |
| CCA | H.5, Work Management |
| INPO aspect | WP.1 |
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Finding - Wolf Creek - IR 05000482/2012009 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2012Q3
Self-Identified List (Wolf Creek)
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