05000458/FIN-2015002-02
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Finding | |
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| Title | Failure to Maintain Design Control for 18 Upgraded Hydraulic Control Unit Accumulators |
| Description | The inspectors identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to verify the adequacy of the design of replacement accumulators, 18 of which were installed in the control rod drive system at the River Bend Station. The accumulators were reverse-engineered, purchased from a commercial supplier (Tobul Accumulator), and dedicated for use as a basic component; however, the licensees technical justification for the acceptability of the reverse-engineered component, contained in Equivalency Evaluation 98-0632-000 was inadequate. The equivalency evaluation failed to verify the adequacy of critical design parameters related to the performance of the accumulators, such as flow rates, leakage rates, pressure ranges of operation, stroke times, temperature ranges of operation, and seismic qualification. This finding was entered into the licensees corrective action program as Condition Report CR-RBS-2014-03118. The performance deficiency is more than minor, and therefore a finding, because it is associated with the equipment performance attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, at the time of installation, the licensee had not taken sufficient actions to ensure that the accumulators could reliably provide the motive force to insert control rods upon a scram initiation signal under all design basis conditions. The inspectors determined the finding to be of very low safety significance (Green) in accordance with Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process for Findings At-Power, dated June 19, 2012. Using Exhibit 2, Mitigating Systems Screening Questions, the inspectors determined that the finding screened as Green because it did not affect other diverse methods of reactor shutdown; it did not involve manipulations that added positive reactivity to the reactor core; it did not affect control rod scram time testing data; and it did not result in the mismanagement of reactivity by the operators. A cross-cutting aspect to this finding is not being assigned as this performance deficiency occurred in 1998 and therefore is not indicative of current licensee performance. |
| Site: | River Bend  |
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| Report | IR 05000458/2015002 Section 4OA5 |
| Date counted | Jun 30, 2015 (2015Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Barrett B Parks G Warnick J Braisted J Jacobson J Ortega-Luciano J Sowa L Micewski R Laura |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - River Bend - IR 05000458/2015002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (River Bend) @ 2015Q2
Self-Identified List (River Bend)
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