05000327/FIN-2007005-02
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Finding | |
|---|---|
| Title | Improper Information Provided for MSPI |
| Description | The inspectors reviewed the importance weighting ratios for both the unavailability and unreliability portions of the five different MSPI indicators as delineated in the MSPI basis document. The inspectors noted that, for Emergency AC Power, a separate ratio was specified for each EDG on each unit so that when calculating MSPI for Unit 1 there was one ratio for EDG 1A, one ratio for EDG 1B, one ratio for EDG 2A, and one ratio for EDG 2B. The importance of the Unit 1 EDGs was higher for the Unit 1 indicator than the Unit 2 EDGs with each Unit 2 EDG having an identical importance for Unit 1. The opposite was true for Unit 2. The Unit 2 EDGs were more important. However, when reviewing the derivation reports for the Emergency AC Power indicator, the inspectors noted that the same importance ratios were used on each EDG for each unit so that each EDG was equally important to each unit. The inspectors determined that the basis document was correct but the importance ratios had been improperly entered into the CDE database that calculated the Emergency AC Power MSPI. In addition, while reviewing the indicator as part of addressing inspector questions, engineering personnel determined that three previous failures not had not been classified properly. The licensee had originally classified a failure of EDG 2A on October 3, 2005, which involved a broken sight glass on one of the generator bearings, as a demand failure based on the inability of the EDG to complete its function. After reviewing it further the licensee realized that the EDG would have started but would not have been able to complete its mission because the bearing would have failed due to loss of oil. Therefore they reclassified the failure of October 3, 2005, as a failure to run. The licensee also determined that two previous failures on July 20, 2006 and August 7, 2007, were not actually failures because the affected equipment was outside the boundary of the system. The as-reported numbers for the Emergency AC Power MSPI for the quarter ending September 2007 were -5.3E-7 for Unit 1 and -5.3E-7 for Unit 2. The effect of the improper use of the importance measures was to change the unreliability portion of the indicator from a negative to positive number while the total indicator remained negative. After adjusting for importance measures the numbers would have been -2.0E-7 for Unit 1 and -7.0E-8 for Unit 2. With the additional classification changes to the failure data the numbers became -1.12E-6 for Unit 1 and -1.17E-6 for Unit 2. While these numbers remained in the green band, the changes also affected earlier time periods. In two previous quarters, June 2006 and March 2007, the Unit 2 indicator was 1.04E-6. Because this information involved licensee failure to provide complete and accurate information concerning a ROP performance indicator, the inspectors determined that it had the potential to impact NRC ability to perform its regulatory function. Enforcement: 10 CFR 50.9 requires that information provided to the NRC be complete and accurate in all material respects. Contrary to this, from July 1, 2006 until December 31, 2007, the licensee provided information regarding the Emergency AC Power MSPI indicator that was inaccurate. Specifically, the importance ratios for both the unavailability and unreliability portions of the indicator were improperly entered into the calculation for determining the indicator resulting in inaccurate reporting of the MSPI for Emergency AC Power. However, this item will remain unresolved pending NRC review of the previous data for the indicator and is identified as URI 05000327,328/2007005-02, Improper Information Provided for MSPI. This item has been entered into the licensees corrective action program as PER 135288. |
| Site: | Sequoyah  |
|---|---|
| Report | IR 05000327/2007005 Section 4OA1 |
| Date counted | Dec 31, 2007 (2007Q4) |
| Type: | URI: |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71151 |
| Inspectors (proximate) | B Miller S Freeman M Speck A Rogers R Nease A Nielsen J Griffis R Taylor W Looe Michelw Loo E Guthrie C Young S Freeman M Speck L Suggs |
| INPO aspect | |
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Finding - Sequoyah - IR 05000327/2007005 | |||||||||||||||||||||||||
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Finding List (Sequoyah) @ 2007Q4
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