XI.M32 (NUREG-2191 R0)
XI.M32 ONE-TIME INSPECTION
Program Description
A one-time inspection of selected components is conducted just prior to the beginning of a subsequent period of extended operation (e.g., prior to the second period of extended operation) in order to verify the system-wide effectiveness of an aging management program (AMP) that is designed to prevent or minimize aging to the extent that it will not cause the loss of intended function during the subsequent period of extended operation. For example, effective control of water chemistry under the Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report AMP XI.M2, “Water Chemistry,” program can prevent some aging effects and minimize others. However, there may be locations that are isolated from the flow stream for extended periods and are susceptible to the gradual accumulation or concentration of agents that promote certain aging effects. This program provides inspections that verify that unacceptable degradation is not occurring.
This program can also be used to verify the lack of significance of an aging effect. Situations in which additional confirmation is appropriate include: (a) an aging effect is not expected to occur, but the data are insufficient to rule it out with reasonable confidence; or (b) an aging effect is expected to progress very slowly in the specified environment, but the local environment may be more adverse than generally expected. For these cases, confirmation demonstrates that either the aging effect is not occurring or that the aging effect is occurring very slowly and does not affect the component’s or structure’s intended function during the subsequent period of extended operation based on prior operating experience (OE) data.
In addition, for steel components exposed to water environments that do not include corrosion inhibitors as a preventive action (e.g., treated water, treated borated water, raw water, waste water), this program verifies that long-term loss of material due to general corrosion will not cause a loss of intended function [e.g., pressure boundary, leakage boundary (spatial), structural integrity (attached)].
This program does not address Class 1 piping less than 4 inches nominal pipe size. That piping is addressed in GALL-SLR Report AMP XI.M35, “ASME Code Class 1 Small-Bore Piping.”
The elements of the program include: (a) determination of the sample size of components to be inspected based on an assessment of materials of fabrication, environments, plausible aging effects, and OE; (b) identification of the inspection locations in the system or component based on the potential for the aging effect to occur; (c) determination of the examination technique, including acceptance criteria that would be effective in managing the aging effect for which the component is examined; and (d) evaluation of the need for follow-up examinations to monitor the progression of aging if age-related degradation is found that could jeopardize an intended function before the end of the subsequent period of extended operation.
The program may include a review of routine maintenance, repair, or inspection records to confirm that selected components have been inspected for aging degradation within the recommended time period for the inspections related to the subsequent period of extended operation, and that significant aging degradation has not occurred. A one-time inspection program is acceptable to verify the effectiveness of GALL-SLR Report AMP XI.M2, “Water Chemistry,” GALL-SLR Report AMP XI.M30, “Fuel Oil Chemistry,” and GALL-SLR Report AMP XI.M39, “Lubricating Oil Analysis,” where the environment in the subsequent period of extended operation is expected to be equivalent to that in the prior operating period and for which no aging effects have been observed. However, the one-time inspection for environments that do not fall in the above category, or of any other action or program created to verify the effectiveness of an AMP and confirm the absence of an aging effect, is to be reviewed by the staff on a plant-specific basis.
This program cannot be used for structures or components with known age-related degradation mechanisms or when the environment in the subsequent period of extended operation is not expected to be equivalent to that in the prior operating period. Periodic inspections are proposed in these cases.
Evaluation and Technical Basis
- 1. Scope of Program: The scope of this program includes systems and components that are subject to aging management using GALL-SLR Report AMP XI.M2, “Water Chemistry,” XI.M30, “Fuel Oil Chemistry;” and XI.M39, “Lubricating Oil Analysis;” and for which no aging effects have been observed or for which the aging effect is occurring very slowly and will not affect the component’s or structure’s intended function during the subsequent period of extended operation based on prior OE data. The scope of this program also may include other components and materials where the environment in the subsequent period of extended operation is expected to be equivalent to that in the prior operating period and for which no aging effects have been observed. The scope of this program includes managing long-term loss of material due to general corrosion for steel components. Long-term loss of material due to general corrosion for steel components need not be managed if one of the following two conditions is met: (i) the environment for the steel components includes corrosion inhibitors as a preventive action; or (ii) wall thickness measurements on a representative sample of each environment will be conducted between the 50th and 60th year of operation. Environments such as treated water, treated borated water, raw water, and waste water do not typically include corrosion inhibitors.
- The program cannot be used for structures or components:
- Subjected to known age-related degradation mechanisms as determined based on a review of plant-specific and industry OE for the prior operating period,
- When the environment in the subsequent period of extended operation is not expected to be equivalent to that in the prior operating period, or
- When aging effects that do not meet acceptance criteria are identified during the one-time inspection conducted in the prior operating period or during the review of plant-specific or industry OE.
- Periodic inspections are proposed in these cases.
- 2. Preventive Actions: One-time inspection is a condition monitoring program. It does not include methods to mitigate or prevent age-related degradation.
- 3. Parameters Monitored or Inspected: The program monitors parameters directly related to the age-related degradation of a component. Examples of parameters monitored and the related aging effect are provided in Table XI.M32-1, “Examples of Parameters Monitored or Inspected and Aging Effect for Specific Structure or Component.” Inspection is performed using a variety of nondestructive examination (NDE) methods, including visual, volumetric, and surface techniques.
| Table XI.M32-1. Examples of Parameters Monitored or Inspected and Aging Effect for Specific Structure or Component1 | |||
|---|---|---|---|
| Aging Effect |
Aging Mechanism |
Parameter(s) Monitored |
Inspection Method2 |
| Loss of Material3 | Crevice Corrosion |
Surface Condition or Wall Thickness |
Visual (e.g., VT-1) or Volumetric (e.g., UT) |
| Loss of Material | General Corrosion |
Surface Condition or Wall Thickness | Visual (e.g., VT-3) or Volumetric (e.g., UT) |
| Loss of Material | Microbiologically influenced Corrosion |
Surface Condition or Wall Thickness | Visual (e.g., VT-3) or Volumetric (e.g., UT) |
| Loss of Material3 | Pitting Corrosion |
Surface Condition or Wall Thickness | Visual (e.g., VT-1) or Volumetric (e.g., UT) |
| Long-term Loss of Material |
General Corrosion |
Wall Thickness | Volumetric (e.g., UT) |
| Reduction of Heat Transfer |
Fouling | Tube Fouling | Visual (e.g., VT-3) |
| Cracking3 | SCC or Cyclic Loading |
Surface Condition or Cracks |
Enhanced Visual (e.g., EVT-1) or Surface Examination (magnetic particle, liquid penetrant) or Volumetric (radiographic testing or UT) |
| |||
- 4. Detection of Aging Effects: Elements of the program include (a) determination of the sample size of components to be inspected based on an assessment of materials of fabrication, environment, plausible aging effects, and OE; (b) identification of the inspection locations in the system or component based on the potential for the aging effect to occur; and (c) determination of the examination technique, including acceptance criteria that would be effective in managing the aging effect for which the component is examined.
- The inspection includes a representative sample of each population (defined as components having the same material, environment, and aging effect combination) and, where practical, focuses on the bounding or lead components most susceptible to aging due to time in service, and severity of operating conditions. A representative sample size is 20 percent of the population or a maximum of 25 components at each unit. Otherwise, a technical justification of the methodology and sample size used for selecting components for one-time inspection is included as part of the program’s documentation.
- The program relies on established NDE techniques, including visual, ultrasonic, and surface techniques. Inspections and tests are performed by personnel qualified in accordance with site procedures and programs to perform the type of examination specified. Inspections and tests within the scope of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) follow procedures consistent with the ASME Code. Non-ASME Code inspections follow site procedures that include inspection parameters for items such as lighting, distance, offset, surface coverage, presence of protective coatings, and cleaning processes. In addition, a description of enhanced visual examination (EVT)-1 is found in Boiling Water Reactor Vessel and Internals Project (BWRVIP)-03(revision referenced is archived) and Materials Reliability Program (MRP)-228(revision referenced is archived).
- When using this AMP to conduct one-time inspections of aluminum piping, piping components and tanks exposed to air, aluminum structures and components (SCs) are grouped by material type. The high strength heat treatable aluminum alloys (i.e., 2xxx and 7xxx series) may be treated as a separate population when performing inspections and interpreting results due to their relatively lower corrosion resistance. The relative susceptibility of moderate and lower strength alloys varies based on composition (primarily weight percent Cu, Mg, and Fe) and temper designation. Grouping of air environments consistent with the Detection of Aging Effects program element of GALL-SLR Report AMP XI.M38 is acceptable.
- In addition, when using this AMP to conduct inspections of stainless steel (SS), nickel alloy, and aluminum components exposed to any air environment or condensation to detect loss of material or stress corrosion cracking, the internal surfaces of these components do not need to be inspected if: (a) the review of plant-specific OE does not reveal a history of pitting or crevice corrosion; and (b) inspection results for external surfaces demonstrate that the aging effect is not applicable. Inspection results associated with the periodic introduction of either moisture or halides from secondary sources (e.g., leaking flanges) may be treated as a separate population of components.
- An inspection of a component in a more severe environment may be credited as an inspection for the specified environment and for the same material and aging effects in a less severe environment (e.g., a high-humidity environment is more severe than an indoor controlled air environment because the moisture in the former environment is more likely to result in aging effects than would be expected from the normally dry surfaces associated with the latter environment). Alternatively, similar environments (e.g., internal uncontrolled indoor, controlled indoor, dry air environments) can be combined into a larger population provided that the inspections occur on components located in the most severe environment (e.g., in the locality of flanges that have leaked in the past).
- For managing long-term loss of material, exceptions need not be stated for the following:
- Conducting wall thickness measurements for long-term loss of material in a different AMP (e.g., AMP XI.M20) as long as the alternative AMP cites the necessary detail (e.g., environment, sample size, purpose of inspection).
- Utilization of the data from recurring internal corrosion wall thickness measurements as long as the material and environment is consistent with that for long-term loss of material.
- The use of scanning techniques (e.g., low frequency electromagnetic testing) as long as the method, coverage, and threshold for follow-up wall thickness measurements when indications are detected are stated in the subsequent license renewal application.
- With respect to inspection timing, the sample of components are inspected before the end of the current operating term to provide reasonable assurance that the aging effect will not compromise any intended function during the subsequent period of extended operation. Inspections need to be timed to allow the inspected components to attain sufficient age such that the aging effects with long incubation periods (i.e., those that may affect intended functions near the end of the subsequent period of extended operation) are identified. Within these constraints, the applicant schedules the inspection no earlier than 10 years prior to the subsequent period of extended operation.
- 5. Monitoring and Trending: Inspection results for each material, environment, and aging effect are compared to those obtained during previous inspections when available. Where practical, these results are trended in order to project observed degradation to the end of the subsequent period of extended operation.
- 6. Acceptance Criteria: The acceptance criteria for this program considers both the results of observed degradation during current inspections and the results of projecting observed degradation of the inspections for each material, environment and aging effect combinations.
- Any indications or relevant conditions are evaluated. Acceptance criteria may be based on applicable ASME Code or other appropriate standards, design basis information, or vendor-specified requirements and recommendations (e.g., ultrasonic thickness measurements are compared to predetermined limits); however, crack-like indications are not acceptable.
- Where it is practical to project observed degradation to the end of the subsequent period of extended operation, the projected degradation will not: (a) affect the intended function of a system, structure, or component; (b) result in a potential leak; or (c) result in heat transfer rates below that required by the current licensing basis to meet design limits.
- Where measurable degradation has occurred, but acceptance criteria have been met, the inspection results are entered into the applicant’s corrective action program for future monitoring and trending.
- 7. Corrective Actions: Results that do not meet the acceptance criteria are addressed in the applicant’s corrective action program under those specific portions of the quality assurance (QA) program that are used to meet Criterion XVI, “Corrective Action,” of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B. Appendix A of the GALL-SLR Report describes how an applicant may apply its 10 CFR Part 50, Appendix B, QA program to fulfill the corrective actions element of this AMP for both safety-related and nonsafety-related SCs within the scope of this program.
- If the cause of the aging effect for each applicable material and environment is not corrected by repair of replacement for all components constructed of the same material and exposed to the same environment, additional inspections are conducted if one of the inspections does not meet acceptance criteria. The number of increased inspections is determined in accordance with the site’s corrective action process; however, there are no fewer than five additional inspections for each inspection that did not meet acceptance criteria, or 20 percent of each applicable material, environment, and aging effect combination is inspected, whichever is less. If subsequent inspections do not meet acceptance criteria, an extent of condition and extent of cause analysis is conducted to determine the further extent of inspections. At multi-unit sites, the additional inspections include inspections at all of the units with the same material, environment, and aging effect combination.
- Where an aging effect identified during an inspection does not meet acceptance criteria or projected results of the inspections of a material, environment, and aging effect combination do not meet the above acceptance criteria, a periodic inspection program is developed for the specific material, environment, and aging effect combination. The periodic inspection program is implemented at all of the units on site with same combination(s) of material, environment, and aging effect.
- 8. Confirmation Process: The confirmation process is addressed through those specific portions of the QA program that are used to meet Criterion XVI, “Corrective Action,” of 10 CFR Part 50, Appendix B. Appendix A of the GALL-SLR Report describes how an applicant may apply its 10 CFR Part 50, Appendix B, QA program to fulfill the confirmation process element of this AMP for both safety-related and nonsafety-related SCs within the scope of this program.
- 9. Administrative Controls: Administrative controls are addressed through the QA program that is used to meet the requirements of 10 CFR Part 50, Appendix B, associated with managing the effects of aging. Appendix A of the GALL-SLR Report describes how an applicant may apply its 10 CFR Part 50, Appendix B, QA program to fulfill the administrative controls element of this AMP for both safety-related and nonsafety-related SCs within the scope of this program.
- 10. Operating Experience: The elements that comprise inspections associated with this program (the scope of the inspections and inspection techniques) are consistent with industry practice. An applicant’s OE with detection of aging effects should be adequate to demonstrate that the program is capable of detecting the presence or noting the absence of aging effects in the components, materials, and environments where one-time inspection is used to confirm system-wide effectiveness of another preventive or mitigative AMP.
- The program is informed and enhanced when necessary through the systematic and ongoing review of both plant-specific and industry OE including research and development such that the effectiveness of the AMP is evaluated consistent with the discussion in Appendix B of the GALL-SLR Report.
References
10 CFR Part 50, Appendix B, “Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants.” Washington, DC: U.S. Nuclear Regulatory Commission. 2016.
10 CFR 50.55a, “Codes and Standards." Washington, DC: U.S. Nuclear Regulatory Commission. 2016.
ASME. ASME Code Section XI, “Rules for Inservice Inspection of Nuclear Power Plant Components.” New York, New York: The American Society of Mechanical Engineers. 2008.
EPRI. BWRVIP-03, Revision 6 (EPRI 105696-R6)(Archived), “BWR Vessel and Internals Project, Reactor Pressure Vessel and Internals Examination Guidelines.” Agencywide Documents Access and Management System Accession No. ML040440261. Palo Alto, California: Electric Power Research Institute. December 2003.
_____. MRP-228, “Materials Reliability Program: Inspection Standard for PWR Internals.” Palo Alto, California: Electric Power Research Institute. 2009.(Archived)