XI.M5 (NUREG-1801 R0)
XI.M5 BWR FEEDWATER NOZZLE
Program Description
This program includes (a) enhanced inservice inspection (IS[) in accordance with the requirements of the American Society of Mechanical Engineers (ASME) Code, Section X1, Subsection IWB, Table IWB 2500-1 (1995 edition through the 1996 addenda) and the recommendation of General Electric (GE) NE-523-A71-0594, and (b) system modifications to mitigate cracking. The program specifies periodic ultrasonic inspection of critical regions of boiling water reactor (BWR) feedwater nozzle.
Evaluation and Technical Basis
- 1. Scope of Program: The program includes enhanced ISI to monitor the effects of crack initiation and growth on the intended function of the component and systems modifications to mitigate cracking.
- 2. Preventive Actions: Mitigation occurs by systems modifications, such as removal of stainless steel cladding and installation of improved spargers. Mitigation is also accomplished by changes to plant-operating procedures, such as improved feedwater control and rerouting of the reactor water cleanup system, to decrease the magnitude and frequency of temperature fluctuations.
- 3. Parameters Monitored/Inspected: The aging management program (AMP) monitors the effects of cracking on the intended function of the component by detection and sizing of cracks by ISI in accordance with ASME Section XI, Subsection IWB and the recommendation of GE NE-523-A71-0594, as described below.
- 4. Detection of Aging Effects: The extent and schedule of the inspection prescribed by the program are designed to ensure that aging effects will be discovered and repaired before the loss of intended function of the component. Inspection can reveal crack initiation and growth. The GE NE-523-A71-0594 specifies UT of specific regions of the blend radius and bore. The UT examination techniques and personnel qualifications are in accordance with to the guidelines of GE NE-523-A71-0594. Based on the inspection method and techniques and plant-specific fracture mechanics assessments, the inspection schedule is in accordance with Table 6-1 of GE NE-523-A71-0594. Leakage monitoring may be used to modify the inspection interval.
- 5. Monitoring and Trending: Inspections scheduled in accordance with GE NE-523-A71 0594 provides timely detection of cracks.
- 6. Acceptance Criteria: Any cracking is evaluated in accordance with IWB-3100 by comparing inspection results with the acceptance standards of IWB-3400 and IWB-3500.
- 7. Corrective Actions: Repair is in conformance with IWB-4000 and replacement in accordance with IWB-7000. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable in addressing corrective actions.
- 8. Confirmation Process: 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 in addressing the confirmation process and administrative controls.
- 9. Administrative Controls: See Item 8, above.
- 10. Operating Experience: Cracking has occurred in several BWR plants (NUREG-0619, US NRC Generic Letter 81-11). This AMP has been implemented for nearly 20 years and found to be effective in managing the effect of cracking on the intended function of feedwater nozzles.
References
ASME Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, ASME Boiler and Pressure Vessel Code, 1995 edition through the 1996 addenda, American Society of Mechanical Engineers, New York, NY.
GE-NE-523-A71-0594, Rev. 1, Alternate BWR Feedwater Nozzle Inspection Requirements, BWR Owner's Group, August 1999.
US NRC Generic Letter 81-11, BWR Feedwater Nozzle and Control Rod Drive Return Line Nozzle Cracking (NUREG-0619), U.S. Nuclear Regulatory Commission, February 29, 1981.
NUREG-0619, BWR Feedwater Nozzle and Control Rod Drive Return Line Nozzle Cracking, U.S. Nuclear Regulatory Commission, November 1980.