05000397/FIN-2016004-02
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Finding | |
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| Title | RCIC Trips After Surveillances |
| Description | Green. The inspectors reviewed a self-revealed, non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to verify the adequacy of design of the reactor core isolation cooling (RCIC) system. Specifically, in 2001, the licensee implemented a design change to the keep-fill pump, RCIC-P-3, that changed its operation from continuous to intermittent, and did not verify the adequacy of the design for all methods of operation, including surveillance testing. Placing the RCIC-P-3 pressure switch downstream of the steam-driven RCIC pumps discharge check valve allows a subsequent hydraulic transient to depressurize RCIC piping below the systems low pressure trip set point. This failure to provide design control measures resulted in RCIC tripping three separate times when RCIC-P-3 was unable to keep up with hydraulic transients. In response to this condition, the licensee changed their operation of the keep-fill pump to running continuously and initiated Action Request 352594 to address long-term issues such as procedure revisions and system design changes. The failure to verify the adequacy of design of the RCIC system was a performance deficiency. Specifically, in 2001, the licensee implemented a design change to the keep-fill pump, RCIC-P-3, that changed its operation from continuous to intermittent and did not verify the adequacy of the design for all methods of operation, including surveillance testing. The performance deficiency was more than minor, and therefore a finding, because it affected the design control attribute of the Mitigating System 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, this modification was inadequate, resulted in RCIC tripping three separate times when RCIC-P-3 was unable to keep up with hydraulic transients, and required compensatory measures to prevent future trips. The inspectors performed the initial significance determination using NRC Inspection Manual Chapter 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions. The inspectors determined that the finding was of very low safety significance (Green) because: (1) the finding was not a deficiency affecting the design or qualification of a mitigating system; (2) the finding did not represent a loss of system and/or function; (3) the finding did not represent an actual loss of function of a single train for greater than its technical specification allowed outage time; and (4) the finding did not represent an actual loss of function of one or more nontechnical specification trains of equipment designated as high safety-significant in accordance with the licensees maintenance rule program for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The inspectors did not identify a cross-cutting aspect for this issue. Specifically, the design change occurred approximately 15 years ago and does not represent current licensee performance. |
| Site: | Columbia  |
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| Report | IR 05000397/2016004 Section 1R15 |
| Date counted | Dec 31, 2016 (2016Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | C Osterholtz D Bradley G Kolcum J Groom J Kirkland S Hedger T. Lamb |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Columbia - IR 05000397/2016004 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Columbia) @ 2016Q4
Self-Identified List (Columbia)
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