05000387/LER-2002-002, Re Main Steam Isolation Valve Total Leakage Exceeded Technical Specification Limit
| ML021330017 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 05/01/2002 |
| From: | Shriver B Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-5474 LER-02-002-00 | |
| Download: ML021330017 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded |
| 3872002002R00 - NRC Website | |
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Bryce L. Shriver Vice President - Nuclear Site Operations PPL Susquehanna, LLC P.O. Box 467, Berwick, PA 18603 Tel. 570.542.3120 Fax 570.542.1477 bishriver~pplweb.com I
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MAY 1 2002 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2002-002-00 PLA - 5474 FILE R41-2 Docket No. 50-387 License No. NPF-14 Attached is Licensee Event Report 50-387/2002-002-00, which discusses exceeding the Technical Specification limit for Main Steam Line valve leakage. This event is reportable in accordance with 10CFR50.73(a)(2)(ii)(A). This event had very low safety significance and there were no actual consequences to the health and safety of the public.
Bryce L. Shriver Vice President - Nuclear Site Operations Attachment cc:
Mr. H. J. Miller Regional Administrator U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 cc:
Mr. S. L. Hansell Sr. Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 35 Berwick, PA 18603-0035
Abstract
On March 3, 2002 with Unit 1 in its twelfth refueling and inspection outage (Mode 4, Cold Shutdown; 0%
Power), an evaluation of the data from the scheduled Main Steam Line (MSL) Local Leak Rate Testing determined that the as-found minimum pathway leakage for the Main Steam Isolation Valves (MSIV) exceeded the Technical Specification limit of 300 Standard Cubic Feet per Hour (SCFH). The total as-found MSL minimum pathway leakage, including subsequent test results from other valves in the MSL minimum pathway category, was 1065 SCFH. The cause of the MSIV leak rate test failures was a valve design that did not properly align seating surfaces during valve closure. Misalignment of the poppet to valve body seating surfaces allowed unacceptable leakage. Each MSIV has been modified with improved design features that will improve the MSIV alignment and sealing performance. This event is reportable as a degraded principal safety barrier per 10CFR50.73(a)(2)(ii)(A). Considering the results of extrapolation of design basis accident analysis, the projected dose results using realistic dose analysis, and the conservative nature of the test results, this event had very low safety significance. There were no actual consequences to the health and safety of the public as a result of this event.
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Considering the results of extrapolation of DBA analysis, the projected dose results using realistic dose analysis and the conservative nature of the test results, this event had very low safety significance.
There were no actual consequences to the health and safety of the public as a result of this event.
This event is reportable as a degraded principal safety barrier per 10CFR50.73(a)(2)(ii)(A). In accordance with guidance in NUREG-1 022, Revision 2, the due date for this report is May 2, 2002.
CORRECTIVE ACTIONS
The corrective actions that have been completed will improve the MSIV alignment and sealing performance. Each Unit 1 MSIV has been modified with the following improved design features:
Nose-guided poppet Stem and poppet anti-rotation feature Backseated poppet Floating pilot poppet Enhanced stem guide Single piece forged stem These improvements have been recommended by the valve manufacturer and have improved MSIV performance and reliability at other plants.
The total as-left minimum path leakage measured after the modifications was approximately 10 SCFH for all four main steam lines.
All Unit 2 MSIVs are scheduled for the same improvements during the Spring, 2003 outage.
ADDITIONAL INFORMATION
Past Similar Events:
Failed Component:
Manufacturer:
Model:
LER 50/387 2000-002-00 LER 50/388 1999-001-00 MSIVs, HV-141F022A/B/C/D and HV-141 FO28AIBIC/D Atwood and Morrill Co., Inc.
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