05000331/FIN-2012002-08
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Finding | |
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Title | Licensee-Identified Violation |
Description | The licensee identified a finding of very low safety significance (Green) and an associated NCV of 10 CFR 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, on December 29, 2011, when sequentiallyperformed functional tests of the LPCI recirculation riser differential pressure instruments failed. Section 4OA3.2 documents the chronology of the instrument conditions and apparent cause. Corrective actions included a revision to I.PDIS-I204-01 to include appropriate vendor manual information, performance of STP 3.3.5.1-22 at an increased frequency, and longer term actions to replace the instruments with a different design and/or pursuance of a TS amendment to broaden the trip setpoints to reduce cycling of the instruments and switches. The failure to assure that I.PDIS-I204-01 was appropriate to the circumstances was a performance deficiency. The performance deficiency was determined to be more than minor and a finding because it was associated with the procedure quality 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 (i.e., core damage). Specifically, LPCI loop select availability and capability was not ensured for approximately 1.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> due to I.PDIS-I204-01 not including available vendor manual information. The inspectors evaluated the finding in accordance with 0609, Significance Determination Process, Attachment 0609.04, Phase 1 - Initial Screening and Characterization of Findings, Table 4a. In the Mitigating Systems Cornerstone, the inspectors answered Yes to the screening question Does the finding represent a loss of system safety function? Therefore, the finding required further risk evaluation. Since the SDP Phase 2 risk tools are being replaced with tools based on the plant-specific Standardized Plant Analysis Risk (SPAR) models, the Region III Senior Risk Analysts (SRAs) performed a Phase 3 risk evaluation using the SPAR model. The risk evaluation was performed using SAPHIRE Version 8.0.7.18 and the Duane Arnold SPAR model (Version 8.18). The increase in core damage frequency (CDF) was analyzed assuming the safety function of LPCI during design basis loss of coolant accidents (LOCAs) was lost. The exposure time was assumed to be 1.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> since this was the duration when the ability of the LPCI loop select logic scheme to select the correct loop for injection was nonfunctional. For the performance deficiency, CDF was only affected during LOCA scenarios. The SRAs used updated LOCA frequency data for large, medium, and small LOCAs from the 2010 reactor operational database maintained by Idaho National Laboratory. The SRAs performed a bounding assessment for the change in CDF by setting all four RHR/LPCI pump fail-to-run values to True (i.e., failed) and solving the LOCA scenarios. The resultant ACDF was 8.9E-8/yr for an exposure time of one year. The actual risk significance is considerably less considering the short exposure time of only 1.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Based on this Phase 3 analysis, the inspectors determined that the finding was of very low safety significance (Green). |
Site: | Duane Arnold ![]() |
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Report | IR 05000331/2012002 Section 4OA7 |
Date counted | Mar 31, 2012 (2012Q1) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | Licensee-identified |
Inspection Procedure: | |
Inspectors (proximate) | R Orlikowski T Bilik M Mitchell M Ring L Haeg K Walton J Draper R Murray S Bell |
INPO aspect | |
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Finding - Duane Arnold - IR 05000331/2012002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Duane Arnold) @ 2012Q1
Self-Identified List (Duane Arnold)
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