ML082530275
| ML082530275 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee  |
| Issue date: | 09/30/2005 |
| From: | - No Known Affiliation |
| To: | NRC/SECY/RAS |
| SECY RAS | |
| References | |
| 06-849-03-LR, 50-271-LR, RAS M-320 | |
| Download: ML082530275 (3) | |
Text
AA's' H *0 U,S. NUCLEAR REGULATORY COMMISSION
_DLXET-S H3OIn the Matter of £L.A i. Ia LJL(
USNRC Docket No .. , 1 Official ExhibitNo. -VY Au g u s t 12 , 2 0 08 ( 11:00 a m) OFFERED by - it i cee Inte er vrveen or OFFICE OF SECRETARY NICStaff O "ler RULEMAKIN GS AND -------
ADJUDICATIONS STAFF IDENTIFIED an21 XI.M17 FLOW-ACCELERATED CORROSION A REJECTED wrnDpTnEw Program Description Repooter,0i -LA A(-
The program relies on implementation of the Electric Power Research Institute (EPRI) guidelines in the Nuclear Safety Analysis Center (NSAC)-202L-R2 for an effective flow-accelerated corrosion (FAC) program. The program includes performing (a) an analysis to determine critical locations, (b) limited baseline inspections to determine the extent of thinning at these locations, and (c) follow-up inspections to confirm the predictions, or repairing or replacing components as necessary.
Evaluation and Technical Basis
- 1. Scope of Program:The FAC program, described by the EPRI guidelines in NSAC-202L-R2, includes procedures or administrative controls to assure that the structural integrity of all carbon steel lines containing high-energy fluids (two phase as well as single phase) is maintained. Valve bodies retaining pressure in these high-energy systems are also covered by the program. The FAC program was originally outlined in NUREG-1 344 and was further described through the Nuclear Regulatory Commission (NRC) Generic Letter (GL) 89-08. A program implemented in accordance with the EPRI guidelines predicts, detects, and monitors FAC in plant piping and other components, such as valve bodies, elbows and expanders. Such a program includes the following recommendations: (a) conducting an analysis to determine critical locations, (b) performing limited baseline inspections to determine the extent of thinning at these locations, and (c) performing follow-up inspections to confirm the predictions, or repairing or replacing components as necessary. NSAC-202L-R2 (April 1999) provides general guidelines for the FAC program. To ensure that all the aging effects caused by FAC are properly managed, the program includes the use of a predictive code, such as CHECWORKS, that uses the implementation guidance of NSAC-202L-R2 to satisfy the criteria specified in 10 CFR Part 50, Appendix B, criteria for development of procedures and control of special processes.
- 2. Preventive Actions: The FAC program is an analysis, inspection, and verification program; thus, there is no preventive action. However, it is noted that monitoring of water chemistry to control pH and dissolved oxygen content, and selection of appropriate piping material, geometry, and hydrodynamic conditions, are-effective in reducing FAC.
- 3. ParametersMonitored/Inspected:The aging management program (AMP) monitors the effects of FAC on the intended function of piping and components by measuring wall thickness.
- 4. Detection of Aging Effects: Degradation of piping and components occurs by wall thinning. The inspection program delineated in NSAC-202L-R2 consists of identification of susceptible locations as indicated by operating conditions or special considerations.
Ultrasonic and radiographic testing is used to detect wall thinning. The extent and schedule of the inspections assure detection of wall thinning before the loss of intended function.
- 5. Monitoring and Trending: CHECWORKS or a similar predictive code is used to predict component degradation in the systems conducive to FAC, as indicated by specific plant data, including material, hydrodynamic, and operating conditions. CHECWORKS is September 2005 XI M-61 NUREG-1801, Rev. 1
acceptable because it provides a bounding analysis for FAC. CHECWORKS was developed and benchmarked by using data obtained from many plants' The inspection schedule developed by the licensee on the basis of the results of such a predictive code provides reasonable assurance that structural integrity will be maintained between inspections. Inspection results are evaluated to determine if additional inspections are needed to assure that the extent of wall thinning is adequately determined, assure that intended function will not be lost, and identify corrective actions.
- 6. Acceptance Criteria:Inspection results are input for a predictive computer code, such as CHECWORKS, to calculate the number of refueling or operating cycles remaining before the component reaches the minimum allowable wall thickness. If calculations indicate that an area will reach the minimum allowed wall thickness before the next scheduled outage, the component is to be repaired, replaced, or reevaluated.
- 7. CorrectiveActions: Prior to service, components for which the acceptance criteria are not satisfied are reevaluated, repaired, or replaced. Long-term corrective actions could include adjusting operating parameters or selecting materials resistant to FAC. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the corrective actions.
- 8. ConfirmationProcess:Site quality assurance (QA) procedures, review and approval processes, and administrative controls are implemented in accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the confirmation process and administrative controls.
- 9. Administrative Controls: See Item 8, above.
- 10. OperatingExperience:Wall-thinning problems in single-1hase systems have occurred in feedwater andcondensate systems (NRC IE Bulletin No. 87-01; NRC Information Notices
[INs] 81-28, 92-35, 95-11) and in two-phase piping in extraction steam lines (NRC INs 89-53, 97-84) and moisture separation reheater and feedwater heater drains (NRC INs 89-53, 91-18, 93-21, 97-84). Operating experience shows that the present program, when properly implemented, is effective in managing FAC in high-energy carbon steel piping and components.
References 10 CFR Part 50, Appendix B-, Quality Assurance Criteria for Nuclear Power Plants, Office of the Federal Register, National Archives and Records Administration, 2005.
10 CFR Part 50.55a, Codes and Standards, Office of the Federal Register, National Archives and Records Administration, 2005.
NRC Generic Letter 89-08, Erosion/Corrosion-InducedPipe Wall Thinning, U.S. Nuclear Regulatory Commission, May 2, 1989.
NRC IE Bulletin 87-01, Thinning of Pipe Walls in Nuclear Power Plants, U.S. Nuclear Regulatory Commission, July 9, 1987.
NUREG-1801, Rev. 1 Xl M-62 September 2005
NRC Information Notice 81-28, Failureof Rockwell-Edward Main Steam Isolation Valves, U.S. Nuclear Regulatory Commission, September 3, 1981.
NRC Information Notice 89-53, Rupture of Extraction Steam Line on High Pressure Turbine, U.S. Nuclear Regulatory Commission, June 13, 1989.
NRC Information Notice 91-18, High-Energy Piping FailuresCaused by Wall Thinning, U.S. Nuclear Regulatory Commission, March 12, 1991.
NRC Information Notice 91-18, Supplement 1, High-EnergyPiping FailuresCaused by Wall Thinning, U.S. Nuclear Regulatory Commission, December 18, 1991.
NRC Information Notice 92-35, Higherthan PredictedErosion/Corrosionin Unisolable Reactor CoolantPressureBoundary Pipinginside Containment at a Boiling Water Reactor, U.S. Nuclear Regulatory Commission, May 6,1992.
NRC Information Notice 93-21, Summary of NRC Staff ObservationsCompiled during EngineeringAudits or Inspections of Licensee Erosion/CorrosionPrograms,U.S. Nuclear Regulatory Commission, March 25, 1993.
NRC Information Notice 95-11, Failureof Condensate PipingBecause of Erosion/Corrosionat a Flow StraighteningDevice, U.S. Nuclear Regulatory Commission, February 24, 1995.
NRC Information Notice 97-84, Rupture in Extraction Steam Piping as.a Result of Flow-Accelerated Corrosion, U.S. Nuclear Regulatory Commission, December 11, 1997.
NSAC-202L-R2, Recommendations for an Effective Flow Accelerated CorrosionProgram, Electric Power Research Institute, Palo Alto, CA, April 8, 1999.
NUREG-1344, Erosion/Corrosion-InducedPipe Wall Thinning in U.S. Nuclear Power Plants, P. C. Wu, U.S. Nuclear Regulatory Commission, April 1989.
September 2005 XI M-63 NUREG-1801, Rev. 1