Pre-Period of Extended Operation (PEO) Implementation
After an extended license is granted, the licensee is responsible for meeting all the commitments made during the license renewal (LR) licensing process. The individual commitments are what have been agreed to between the licensee and the United States Nuclear Regulatory Commission (U.S. NRC) and can be found in the license renewal application (LRA) and other LR-related docketed correspondence. These LR commitments are typically summarized in an appendix of the safety evaluation report (SER) documenting the approval of the renewed license. Commitments can be specific to Aging Management Programs(AMPs) but can also be independent of any AMP.
Part of this Pre-Period of Extended Operation (PEO) Implementation task is to perform all the inspections and document updates that were committed to be performed prior to entry into the PEO. The final portion of this implementation task includes providing the documented objective evidence that these inspections/commitments are complete, which the regulator will review during their (U.S. NRC) Pre-PEO Inspections.
This can be a very time-intensive and laborious task and should not be taken lightly. Most pre-PEO inspections can be performed within 5-10 years of entry into the PEO. It is best to take advantage of the time allotted for these inspections and document updates, so that there is not a tidal wave of work that needs to be done just prior to the PEO. The Pre-PEO Implementation task includes (but is not limited to) plant-specific inspections, program implementing documentation, specialty contractor tasks and preparations for regulatory inspections.
Plant-Specific Inspections[edit]
Plant-specific inspections vary from site-to-site, based on commitments, but generally include a substantial number of visual or non-destructive examinations (NDE) of individual plant components. Each site will have their own list of specific inspection requirements. Below is a list of some of the more standard inspections required for LR.
- One-Time Inspections (OTI): typically 200-400 inspections of individual components. These are typically visual inspections of internal surfaces when components are opened, or they are ultrasonic (UT) thickness tests taken from external surfaces. Both these inspection methods can be used to determine loss of material. If cracking is an aging effect requiring management, then other NDE techniques that can identify cracking need to be used (e.g. enhanced visual test (EVT), dye penetrant test (DPT), UT, radiography test (RT), magnetic particle test (MT))
- Useful EPRI resource:
- EPRI Report 3002000459 “NDE: Update on License Renewal One-Time Inspection and Best NDE Practices, Rev. 1”
- Useful EPRI resource:
- Selective Leaching Inspections (if applicable): typically 60-80 inspections of components that are susceptible to selective leaching. These inspections are typically visual inspections of the wetted surfaces of the component. Cast iron materials require an additional mechanical test (scratching or scraping). Some destructive tests will likely be required, in which the component is removed from the system and sent to a lab where it is bisected and analyzed for the presence of selective leaching.
- Useful EPRI resources:
- EPRI report 3002026340, “Recommendations for Implementing an Effective Program to Manage Selective Leaching Degradation”
- EPRI report 3002023785, “Evaluation of Electromagnetic NDE Techniques for Detection of Wall Thinning Due to Selective Leaching Degradation in Gray Cast Iron Piping”
- EPRI Report 3002020832, “Electromagnetic NDE Techniques for Detection of Selective Leaching in Gray Cast Iron Piping”
- EPRI Report 3002020830, “Ultrasonic NDE Techniques for Detection of Selective Leaching in Complex Shaped Gray Cast Iron Components”
- EPRI Report 3002020822, “Accelerated Testing and Evaluation of Factors Affecting Selective Leaching Susceptibility”
- EPRI Report 3002016057, “Selective Leaching: State-of-the-art Technical Update”
- EPRI Report 3002013168, “Nondestructive Evaluation: Guidance for Conducting Ultrasonic Examinations for the Detection of Selective Leaching”
- Useful EPRI resources:
- Buried Piping Inspections: the number of these inspections is dependent on the amount/linear feet of buried components at the site. A site will likely have an existing Underground Piping Program per NEI 09-14, “Guideline for the Management of Underground Piping and Tank Integrity”, but LR requirements may be in addition to those inspections required by the Nuclear Energy Institute (NEI) program.
- Useful EPRI resources:
- EPRI Report 3002018352, “Recommendations for an Effective Program to Control the Degradation of Buried and Underground Piping and Tanks”
- EPRI Report 3002018353, “The Buried and Underground Piping and Tank Reference Guide: Revision 2”
- BPWORKS, Data Management and Risk Ranking for Buried, Underground and Raw Water Piping, V3.0
- EPRI Report 3002013156, “Roadmap to Integrity Evaluation and Repair of Nuclear Plant Piping”
- EPRI Report 3002005294, “Soil Sampling and Testing Methods to Evaluate the Corrosivity of the Environment for Buried Piping and Tanks at Nuclear Power Plants”
- EPRI Report 3002000596, “Cathodic Protection Application and Maintenance Guide: Volume 1 and Volume 2”
- EPRI Report 3002002949, “Recommendations for Managing an Effective Cathodic Protection System”
- EPRI Report 3002004395, “Nondestructive Evaluation: Buried Pipe NDE Reference Guide”
- EPRI Report 3002010027, “Nondestructive Evaluation: Assessment and Development of Buried Pipe NDE Technology”
- Useful EPRI resources:
- American Society of Mechanical Engineers (ASME) Class I Small-Bore Inspections: these inspections require volumetric NDE exams to identify potential cracking in ASME Class 1 small-bore piping that is not inspected per the ASME Section XI code requirements. These exams include socket welded components, which are not typically inspected via volumetric means, due to the geometry of the socket. Therefore, special volumetric techniques for socket welded locations are needed.
- Useful EPRI resource:
- Materials Reliability Program (MRP) - Materials Research Focus Area(MRFA)4- Low Alloy Steels Wiki
- EPRI Report 3002023888, “Procedure for Encoded Phased Array Ultrasonic Examination of Small-Bore Socket Fillet Welds: EPRI-SW-PA-1 Revision 3”
- EPRI Report 3002018251, “Materials Reliability Program: Guidance for the Mitigation of Vibration Fatigue in Light Water Reactor Small Bore Piping”
- EPRI Report 3002023883, “Materials Reliability Program: Examination of Small Bore Socket Welds for Vibration and Thermal Fatigue”
- EPRI Report 3002017285, "Materials Reliability Program: NDE Technology for Detection of Thermal Fatigue Damage in Piping, Revision 3 (MRP-23)"
- EPRI Report 3002023885, "Materials Reliability Program: Computer-Based Training for Thermal Fatigue Cracking, Revision 5 (MRP-36)"
- EPRI Report 3002023887, "Guidance for Performing Thermal Fatigue Examinations When Utilizing Generic Procedure PDI-UT-2 Revision 1"
- Useful EPRI resource:
- Fire Water Inspections: these inspections can include system pressure monitoring, system flow testing, periodic flushing, wall thickness evaluations (UT or visual), and testing of sprinkler heads.
- Useful EPRI resources:
- EPRI TR-109633, Guideline for the Evaluation and Treatment of Corrosion and Fouling in Fire Protection Systems (Updates of this report will be available Sept 2024 and also Q1 2025)
- EPRI 1016686, Plant Support Engineering: Life Cycle Management Planning Sourcebooks
- EPRI 1006756, Fire Protection Equipment Surveillance Optimization and Maintenance Guide
- Useful EPRI resources:
- Internal Tank Inspections: these inspections are focused on the condition of the internal surfaces of the tank, and in particular, the floor of the tank, which may be on a pedestal or concrete base, or buried. This may require draining and cleaning of the tank (which can be a very complex and expensive task) in order to perform these UT exams.
- Useful EPRI Resources:
- EPRI Report 3002003071, “Guidelines for Tank Inspections”
- EPRI Report 3002013172, “Nondestructive Evaluation (NDE): Assessments for Tanks and Containment Liners: Readily Available NDE Methods to Inspect Tanks and Containment Liners”
- Useful EPRI Resources:
- Internal Coating/Linings Inspections: internal surfaces of some components can be coated or lined to help prevent age-related degradation. However, operating experience (OE) has shown that these coating/linings can sometimes become detached from the internal surface and can cause flow blockage or damage to down-stream components. Inspections of this type require the system to be opened to inspect the condition of these coatings/linings.
- Useful EPRI resources:
- EPRI Report 1025323 Field Guide: Coatings Assessment
- EPRI Report 1014883 Plant Support Engineering: Adhesion Testing of Nuclear Coating Service Level I Coatings
- EPRI Report 1013465 Plant Support Engineering: Aging and Degradation Survey for Nuclear Service Level I Coatings
- EPRI Report 3002005223, Survey for Service Life and Failure History of Immersion Coatings (epri.com)
- Useful EPRI resources:
- External Surfaces inspections: components that may be subject to leakage from external sources and/or condensation may require inspection to ensure no substantial external degradation is occurring. This may include some under-insulation inspections.
- Civil/Structural inspections: these inspections include area walkdowns to check for structural degradation effects, including structural bolting, on a five-year interval. Groundwater sampling may be required on a periodic basis to assess the impact of groundwater chemistry on below grade concrete.
- Electrical Cable Inspections and Testing: these inspections cover in-scope cables in a wide variety of voltage levels, and also would include adverse local environment (ALE) inspections. These ALE inspections look for areas where elevated localized temperatures or localized elevated radiation levels may cause adverse cable insulation degradation. Cables in these ALE areas are then more closely inspected for cable insulation degradation. There are also a number of testing regimens that can be used to test cable insulation integrity. One degradation mechanism in particular is water-treeing, which can happen to cables that are submerged for long periods of time.
- Useful EPRI resources:
- EPRI Report 1021070, “Medium Voltage Cable Aging Management Guide, Revision 1”
- EPRI Report 3002000557, “Plant Engineering, Aging Management Program Guidance for Medium-Voltage Cable Systems for Nuclear Power Plants, Revision 1”
- EPRI Report 3002010641, “Low-Voltage and Instrumentation and Control Cable Aging Management Guide, Revision 1”
- EPRI Report 3002020818, "Test Protocol for Condition Monitoring of Low Voltage Cable Using Dielectrically Based Methods"
- EPRI Cable Aging Wiki
- Useful EPRI resources:
- Cable Connector and Metal Enclosed Bus (MEB ) Inspections: visual inspections of cable connections and inside of MEBs may be required, to look for degradation mechanisms like overheating, corrosion, joint loosening, etc.
- Useful EPRI Resources:
- EPRI 1015057, Nuclear Maintenance Applications Center: Isolated Phase Bus Maintenance Guide
- EPRI 3002000707, Lessons Learned from Exelon’s Non-Segregated Bus Inspections
- EPRI 1013457, Nuclear Maintenance Applications Center: Switchgear and Bus Maintenance Guide
- EPRI 1003471, Electrical Connector Application Guidelines
- Useful EPRI Resources:
- Existing Programs: many other programs at sites are already well-developed, implemented, and in use, such as Steam Generators, ASME Section XI programs, Water Chemistry, Fuel Oil Chemistry, etc. Inspections required by those programs will continue into the PEO but are not typically considered additional LR inspections.
Program Implementing Document Updates[edit]
Each AMP has various site-specific implementing documents, where the requirements within the AMP are included in site procedures/work plans. Details within the AMPs or the commitments will typically describe which implementing documents need to be revised or created.
- Procedure enhancements: typically about 200-250 implementing documents will need to be updated to reflect the requirements/commitments agreed to in the LRA/SER.
- New procedure generation: new procedures may need to be created if there is no other specific document available to control the requirements/commitments in the LRA/SER.
- Preventive Maintenance (PM) enhancements/creation for on-going inspections: this is needed for inspections that will be repeated over time (e.g. monthly, yearly, every refueling cycle, every 10 years, etc.)
- Work Order (WO) creation and planning for various one-time inspections: the one-time inspections will typically require an individual WO to be created and managed within the site’s Work Management and scheduling process. There can be on the order of 1000 individual one-time inspections across all LR programs.
Typical Specialty Contractor Tasks[edit]
Some of the required inspections or evaluations may require a specialty contractor to perform, based on special technical expertise, or by the Original Equipment Manufacturer (OEM) due to proprietary information.
- Fatigue analysis, including Environmentally Assisted Fatigue (EAF)
- Flaw Tolerance evaluations
- Major component inspections or evaluations (Reactor Vessel Internals, Reactor Coolant pumps, Steam Generators, Cast Austenitic Stainless Steel (CASS) components, overhead cranes)
- Vessel surveillance (Fluence projections, sample testing, Pressurized Thermal Shock (PTS) and Upper Shelf Energy (USE) evaluations).
- Environmental Qualification (EQ) updates. Components within the EQ program have a calculated qualified life, and with extensions of the operating license, these need to be reviewed and amended, as necessary, to match the new license period.
Preparation for Pre-PEO Regulatory Inspections[edit]
Each site will need to prepare for the pre-PEO regulatory inspections. There will be a large amount of documentation that the regulator will likely review in these inspections, and it will be important to provide succinct summaries of each program and commitment, along with complete objective evidence to demonstrate compliance with all program requirements and commitments. The following list includes some of the typical topics or information needed to be prepared for the pre-PEO inspections:
- AMP Owner selection and training: Each individual AMP will likely need an AMP Owner who has overall responsibility for the implementation of that AMP. These individuals are typically plant personnel who may not have been involved in the actual LR activities, so they may need some training to come up-to-speed with the requirements within their respective AMPs. The regulator is likely to interview AMP Owners during the pre-PEO inspections.
- Generate a Completion Binder for each program and/or commitment: provide objective evidence demonstrating completion of each requirement/commitment, including copies of:
- Implementing documents that were generated or enhanced. It is ultimately helpful to list individual steps of a procedure or other documentation that specifically meets a commitment.
- Work Management documentation for each individual inspection with results attached
- Inspection Summaries: for those programs that use the results of individual inspections as a basis for concluding that aging is managed, (e.g. One-Time Inspection – the results of OTI exams will demonstrate that Water Chemistry is adequately managing aging, or conversely, that periodic inspections may be required).
- Generate a Commitment Closure Summary for each commitment: this can be a subset of a commitment tracking program used by the site, or a specific LR commitment tracker. Either way, each individual commitment will need to be addressed to demonstrate closure. Some commitments have numerous sub-steps, so it is critical that each sub-step be tracked and documented for closure. These Closure Summaries can be either hardcopy or electronic, although electronic is recommended.
- Some commitments that continue throughout the PEO may be closed by showing that there are procedures in place to continue to implement the commitment and these procedures are annotated as being LR commitments. An example is the Water Chemistry Program which was in existence since initial plant start and will continue until the plant is shutdown.
- Peer Review of the closeout documentation: as part of a preparation for the US NRC Pre-PEO Inspections, a site will typically engage a number of peer reviewers to review the documentation and provide feedback on the quality and completeness of that documentation. This needs to be scheduled a few months in advance of the US NRC Inspections, so a site has an opportunity to resolve any issues identified in the peer review.
Regulatory Guidance[edit]
Pre-PEO inspections are driven by applicable national regulatory framework, in the United States by the US NRC Inspection Procedures IP-71003 Series. These inspection procedures (IPs) will provide the licensee the information that the regulator is looking for during their inspections.
Per 10 CFR 54.37(b), after a renewed license is issued, the licensee must also perform annual updates to include newly identified components that would have been subject to aging management review (AMR) or Time Limited Aging Analysis (TLAA). Additional guidance for meeting these requirements is provided by the NRC in RIS-07-16 Rev. 1, Implementation of the Requirements of 10 CFR 54.37(b) for Holders of Renewed Licenses.
Industry Resources[edit]
The NEI License Renewal Task Force (LRTF) meets periodically to exchange information from recent audits and submittals, and to share site experiences and issues.
Boiling Water Reactors Owners Group (BWROG) provides the industry with various forms of assistance and technical input for General Electric BWR plants.
Pressurized Water Reactors Owners Group (PWROG) provides the industry with various forms of assistance and technical input for PWR plants.
Record of Revisions[edit]
| Number | Date | Description of Changes |
|---|---|---|
| 0 | 6/11/2024 | Initial version |