NOC-AE-02001343, Response to Request for Additional Information Re Containment Purge Valve Test Interval Proposed Amendment from South Texas Project
| ML022100027 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/23/2002 |
| From: | Jordan T South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NOC-AE-02001343 | |
| Download: ML022100027 (8) | |
Text
ALM Nuclear Operating Company South Tees Pro/ectEkctnc Generaing Station PO Box 289 Wadsworth. Texas 77483 July 23, 2002 NOC-AE-02001343 File No.: G25 10CFR50.90 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Response to Request for Additional Information Containment Purge Valve Test Interval Proposed Amendment
Reference:
Letter from J. J. Sheppard to NRC Document Control Desk, "Proposed Amendment to Technical Specification 3/4.6.1.7, 'Containment Ventilation System,' for Containment Purge Valve Operability Test Interval," dated February 18, 2002 (NOC-AE-02001237)
The South Texas Project submits the attached information in response to the NRC request for additional information regarding our request to extend the interval between containment purge valve tests to 18 months. The extension request is applicable to South Texas Project Unit 1 and Unit 2.
If there are any questions, please contact either Mr. P. L. Walker at (361) 972-8392 or me at (361) 972-7902.
I state under penalty of perjury that the foregoing is true and correct.
Executed on J,,)A ZSzooz T. J. Jordan Vice President, Engineering & Technical Services PLW
Attachment:
Response to Request for Additional Information Containment Purge Valve Test Interval Proposed Amendment
NOC-AE-02001343 Page 2 of 2 cc:
(paper copy) (electronic copy)
Ellis W. Merschoff A. H. Gutterman, Esquire Regional Administrator, Region IV Morgan, Lewis & Bockius LLP U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 M. T. Hardt/W. C. Gunst Arlington, Texas 76011-8064 City Public Service U. S. Nuclear Regulatory Commission Mohan C. Thadani Attention: Document Control Desk U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike R. L. Balcom Rockville, MD 20852 Reliant Energy, Inc.
Richard A. Ratliff A. Ramirez Bureau of Radiation Control City of Austin Texas Department of Health 1100 West 49th Street C. A. Johnson Austin, TX 78756-3189 AEP - Central Power and Light Company Cornelius F. O'Keefe Jon C. Wood U. S. Nuclear Regulatory Commission Matthews & Branscomb P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704
Attachment NOC-AE-02001343 Page 1 of 6 South Texas Project Units 1 and 2 Response to Request for Additional Information Containment Purge Valve Test Interval Proposed Amendment Question (1)
The staff noted a previous South Texas Project proposed license amendment related to frequency of leakage rate testing of the normal and supplementary containment purge valves was submitted by the licensee on May 1, 1996. At that time, the staff denied this proposed license amendment as documented in a letter to the licensee dated August 13, 1996.
Provide a technical justification that demonstrates a significant improvement in current purge valves' test performance when compared to the previous purge valve test performance results submitted in May of 1996.
Response (1)
The South Texas Project noted in Section 5.2 that criteria other than Option B of Appendix J are applied to purge valves with resilient seals. A portion of the proposed license amendment submitted on May 1, 1996, was disapproved by the NRC because the test intervals were not consistent with the findings of Generic Issue B-20, "Containment Leakage Due to Seal Degradation."
South Texas Project purge valve test data are provided in the attached Tables 1 and 2. Unit 1 experienced seven test failures from various causes over the eight years of plant operation prior to May 1996, compared with only two in the subsequent six years. Similarly, Unit 2 has had six failures prior to 1996, and none since. This indicates a substantial improvement in component reliability since submittal of the initial license amendment request in 1996.
Question (2)
By letter dated February 18, 2002, the licensee documented the containment penetration test results with unacceptable seat leakage. Provide a technical justification demonstrating improved performance that supports the current proposed license amendment when compared to testing results utilized in the previously referenced May 1996 submittal. The technical justification should include the following:
"* Analysis of containment valve leakage data relative to limits in the technical specifications.
"* Analysis of containment valve leakage data relative to maintenance and administrative limits.
"* Analysis of why containment purge valves' leakage test performance has improved when compared to the South Texas historical results.
Response (2)
Technical Specification leakage limits for normal and supplementary containment purge valves are given as 0.05 La and 0.01 La, respectively. Actual test limits for normal and supplementary purge valves are 25,872 sccm and 6,000 sccm for administrative limits, and 37,920 sccm and 7,584 sccm for Technical Specification limits.
The attached Tables 1 and 2 list the various valve test failures and how the test results compare with Administrative and Technical Specification limits.
Attachment NOC-AE-02001343 Page 2 of 6 Test performance of purge valves has improved due to understanding previous failures and implementation of effective corrective actions. Past failures were primarily caused by incorrect limit switch settings. Resilient seals have not been a significant source of test leakage since early in the plant operating history. Since 1996, the only test failure involving a resilient seal penetration was M-41 in Unit 1, which occurred in April 1999.
Application of lessons learned from experience with previous test failures is the greatest contributing factor for the improvement in test performance.
Question (3)
Provide technical justification in support of the South Texas proposed license amendment by demonstrating improved reliability of the normal containment and supplementary containment purge inboard and outboard valves since commercial operation. The licensee's technical justification should include a comparison of industry operating experience for similar containment purge valves in comparable service that supports current leakage test performance.
Response (3)
Test data for the South Texas Project purge valves are provided in the response to Question 1.
From 1988 to 1996 there were 13 purge valve test failures for both Units, and only two such failures from 1996 to the present. The test data trend indicates improving reliability of the containment purge valves.
Licensee Event Reports addressing purge valves were reviewed for instances of degraded resilient seals. Fermi 2 reported mechanical degradation of a resilient seal in a Licensee Event Report dated October 25, 1999. The reported event involved a 24-inch butterfly valve subjected to quarterly testing, compared to the 48-inch (semi-annual testing) and 18-inch (quarterly testing) butterfly valves used at the South Texas Project. Containment purge valve resilient seals have not been a significant source of problems reported in Licensee Event Reports.
Question (4)
Provide an analysis of all corrective actions associated with the normal and supplementary containment purge valves including use of a corrective action cause determination (i.e., root or apparent cause) process linked to corrective actions to prevent recurrence. Assessment of effectiveness of action to prevent recurrence should demonstrate current and sustained test performance improvements in support of the proposed amendment request.
Response (4)
Where containment purge valves do not meet test result acceptance criteria, condition reports are prepared to ensure that the issue is tracked until corrective measures are implemented.
Tables 3 and 4 identify the corrective actions taken in response to unsatisfactory normal and supplementary purge valve test results, and their effectiveness.
Attachment NOC-AE-02001343 Page 3 of 6 Table 1 UNIT 1 CONTAINMENT PURGE VALVE TEST FAILURE RESULTS Valve Valve Date of Test Administrative Tech Spec Application Failure Limit Failure Limit Failure (sccm) (sccm)
(Normal = 25,872 (Normal = 37,920 Supplementary = Supplementary =
6,000) 7,584)
M-41 Normal Purge 08/14/89 Could not obtain N/A Exhaust test pressure 04/12/99 Could not obtain N/A test pressure M-42 Normal Purge 11/30/93 Could not obtain N/A Supply test pressure 07/06/94 Could not obtain N/A test pressure M-43 Supplementary 01/14/88* N/A 49,000 Purge Supply 07/19/89 Could not obtain N/A test pressure 11/06/90 Could not obtain N/A test pressure 07/13/99 N/A 18,860 M-44 Supplementary 04/12/88 Could not obtain N/A Purge Exhaust test pressure
- The Unit 1 operating license was not issued until March 22, 1988.
Attachment NOC-AE-02001343 Page 4 of 6 Table 2 UNIT 2 CONTAINMENT PURGE VALVE TEST FAILURE RESULTS Valve Valve Date of Test Administrative Tech Spec Application Failure Limit Failure Limit Failure (sccm) (sccm)
(Normal = 25,872 (Normal = 37,920 Supplementary = Supplementary =
6,000) 7,584)
M-41 Normal Purge 04/13/94 Could not obtain N/A Exhaust test pressure M-42 Normal Purge 11/29/88* Could not obtain N/A Supply test pressure 03/18/94 Could not obtain N/A test pressure M-43 Supplementary 04/15/94 Could not obtain N/A Purge Supply test pressure 12/19/94 Could not obtain N/A test pressure M-44 Supplementary 11/29/88* Could not obtain N/A Purge Exhaust test pressure
- The Unit 2 operating license was not issued until March 30, 1989.
Attachment NOC-AE-02001343 Page 5 of 6 Table 3 UNIT 1 CONTAINMENT PURGE VALVE TEST FAILURE ASSESSMENT Valve Valve Date of Test Failure Cause Corrective Action Effectiveness Application Failure M-41 Normal Purge 08/14/89 Valve failed to close Limit switch out of Adjusted limit switch No recurrence Exhaust completely adjustment 04/12/99 Incomplete seal T-Ring Replaced T-Ring No recurrence M-42 Normal Purge 11/30/93 Valve failed to close Limit switch, Re-worked limit No recurrence Supply completely torque switch switch/torque switch 07/06/94 Valve failed to close Unknown Closed disc by hand No recurrence completely M-43 Supplementary 01/14/88* Incomplete seal Valve seat Replaced valve Not Applicable Purge Supply 07/19/89 Incomplete seal Valve disc stem Replaced stem No recurrence for assembly and seat assembly and seat disc stem assembly 11/06/90 Incomplete seal Valve seat Replaced valve seat No recurrence 07/13/99 Valve failed to close Adjustment screw Adjusted screw No recurrence completely M-44 Supplementary 04/12/88 Incomplete seal Valve seat and Replaced seat and No recurrence Purge Exhaust gasket gasket
- The Unit 1 operating license was not issued until March 22, 1988.
Attachment NOC-AE-02001343 Page 6 of 6 Table 4 UNIT 2 CONTAINMENT PURGE VALVE TEST FAILURE ASSESSMENT Valve Valve Date of Test Failure Cause Corrective Action Effectiveness Application Failure M-41 Normal Purge 04/13/94 Valve failed to Limit switch out of adjustment Adjusted limit switch No recurrence Exhaust close completely M-42 Normal Purge 11/29/88* Valve failed to Valve actuator out of Adjusted valve No recurrence Supply close completely adjustment actuator 03/18/94 Valve failed to Limit switch out of adjustment Adjusted limit switch No recurrence close completely M-43 Supplementary 04/15/94 Valve failed to Limit switch Adjusted limit switch No recurrence Purge Supply close completely and stop nuts 12/19/94 Valve failed to Packing leaks, spring Replaced valve Not Applicable close adjustment, seat repair/replacement.
M-44 Supplementary 11/29/88* Incomplete seal Dirt buildup on valve disc Replaced seat ring No recurrence Purge Exhaust and gaskets
- The Unit 2 operating license was not issued until March 30, 1989.