05000483/FIN-2015009-01
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Finding | |
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| Title | Failure to Verify the Suitability of the Design of the Reverse-Engineered Replacement Controller Cards for the Auxiliary Feedwater Flow Control Valves |
| Description | The team identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to assure that the design of the replacement reverse-engineered Modutronics controller cards for the auxiliary feedwater control valves were suitable for their application. Specifically, as of August 11, 2015, the licensee failed to establish suitable interface requirements in procurement documents to Nuclear Logistics Incorporated (the vendor) and verify the adequacy of the design by either design reviews or testing. Specifically, the team identified that neither the licensee nor the vendor had performed a design review sufficient to assure that the Modutronics controller cards were suitable for their application. In addition, the licensee had not provided the vendor with sufficient information to reverse-engineer the controller cards. Lastly, neither the licensee nor the vendor performed testing sufficient to verify the adequacy of the design of the new Modutronics controller cards. As a result, the replacement cards were supplied with motor field current rectifier bridges that were undersized and marginal for their application, such that two of them failed in service, rendering these auxiliary feedwater system valves inoperable. Following performance of a root cause analysis, the licensee replaced the deficient controller cards with those of a higher current rating. The licensee initiated Callaway Action Request 201505796 to place this item into the corrective action program. The failure to ensure that the design of the replacement for the Modutronics cards was suitable for their application was a performance deficiency. This performance deficiency is more than minor, and therefore, a finding because it adversely affected the Mitigating Systems Cornerstone attribute of Design Control and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, design deficiencies associated with these circuit cards resulted in the inoperability of auxiliary feedwater control valves and their ability to operate on demand. The team performed an initial screening of the finding in accordance with Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Inspection Manual Chapter 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions, dated June 19, 2012, the team determined that the finding required a detail risk evaluation because it represented the potential loss of one train of safety-related equipment (auxiliary feedwater) for greater than the technical specification allowed outage time. A Region IV senior reactor analyst performed a detailed risk evaluation in accordance with Appendix A, Section 6.0, Detailed Risk Evaluation, which determined that the finding was of very low safety significance (Green). The analyst determined that the importance of the failure of valves ALHV0005 and ALHV0007 was based on the postulated failure time of the turbine-driven auxiliary feedwater pump because this determined the position in which the valves failed. The internal events incremental conditional core damage probability was 8.17 x 10-7. The analyst also determined that the finding had only a minimal effect on external initiator risk and that the finding would not involve a significant increase in the risk of a large, early release of radiation. This finding has a human performance cross-cutting aspect in the area of teamwork, because individuals in different work groups did not appropriately communicate across organizational boundaries. Specifically, licensee personnel did not adequately communicate the design and testing requirements for the reverse engineered cards (H.4). |
| Site: | Callaway  |
|---|---|
| Report | IR 05000483/2015009 Section 4OA5 |
| Date counted | Dec 31, 2015 (2015Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 93812 |
| Inspectors (proximate) | D Proulx J Jacobson N Taylor R Kopriva |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control Technical Specification |
| CCA | H.4, Teamwork |
| INPO aspect | PA.3 |
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Finding - Callaway - IR 05000483/2015009 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Callaway) @ 2015Q4
Self-Identified List (Callaway)
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