NLS2025055, Proposed Alternative RR6-02 to Use ASME Code Case N-752-1, Risk-informed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems, Section XI, Division 1

Proposed Alternative RR6-02 to Use ASME Code Case N-752-1, Risk-informed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems,Section XI, Division 1

ML25316A006
Person / Time
Site:	Cooper
Issue date:	10/30/2025
From:	Dia K Nebraska Public Power District (NPPD)
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NLS2025055
Download: ML25316A006 (1)

Text

N Nebraska Public Power District "Alway there wlvn 1ou need us" 10 cFR 50.55a(z)(1)

N152025055 October 30,2025 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Proposed Alternative RR6-02 to Use ASME Code Case N-752-1, "Risk-lnformed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems, Section Xl, Division 1" Cooper Nuclear Station, Docket No. 50-298, Renewed License No. DPR-46 Pursuant to 10 CFR 50.55a(z)(1), Nebraska Public Power District (NPPD) hereby requests Nuclear Regulatory Commission (NRC) authorization to utilize proposed alternative RR6-02 to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section Xl, "Rules for lnservice lnspection of Nuclear Power Plant Components."

Specifically, NPPD is requesting to use the alternative requirements of ASME Code Case N-752-1, "Risk-lnformed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems, Section Xl, Division '1," for determining the risk-informed categorization and for implementing alternative treatment for repair/replacement activities on Class 2 and 3 items in lieu of certain ASME Code, Section Xl, paragraph IWA-1000, IWA-4000, and IWA-6000 requirements. NPPD requests approval on the basis that the proposed alternative provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1). The Attachment provides the basis for the request.

NPPD requests NRC authorization of proposed alternative RR6-02 by March 1,2026, in support of the start of the sixth lnservice lnspection lnterval.

No formal regulatory commitments are being made or modified in this submittal.

Should you have any questions regarding this matter, please contact Linda Dewhirst, Regulatory Affairs and Compliance Manager, at(402) 825-5416.

Sincerely, lDia Site Vice President COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-381 1 I F axl- (402) 825-521 1 http://www.nppd.com

/sn

N1S2025055 Page 2 ot 2

Attachment:

cc:

Request for Alternative RR6-02 in Accordance with 10 CFR 50.55a(z)(1) to Use ASME Code Case N-752-1, "Risk-lnformed Categorization and Treatment for Repair/ReplacementActivities in Class 2and 3 Systems, Section Xl, Division 1" Regional Administrator M attachment USNRC - Region lV Cooper Project Manager M attachment USNRC - NRR Plant Licensing Branch lV Senior Resident lnspector M attachment USNRC - CNS NPG Distribution w/ attachment CNS Records W attachment

N152025055 Page 1 of 14 Attachment Cooper Nuclear Station Request for Alternative RR6-02 in Accordance with 10 CFR 50.55a(z)(1) to Use ASME Code Case N-752-1, "Risk-lnformed Gategorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems, Section Xl, Division 1"

1. American Societv of Mechanical Enqineers (ASME) Code Gomponents Affected This request applies to ASME Class 2 and 3 items or components except the following:

r Class Concrete Containment (CC) and Metal Containment (MC) items.

. Piping within the break exclusion region [> Nominal Pipe Size (NPS) 4 (DN 100)] for high energy piping systemsl as defined by the Owner.

2. Applicable Code Edition and Addenda

The proposed alternative is being requested for the sixth ln-Service lnspection (lSl) interval, which is scheduled to begin on March 1, 2026. The edition of the ASME Code Section Xl which will be in use for the sixth lSl interval will be the 2019 Edition (Reference 8.1 ).

3. Applicable Code Requirement

ASME Code, Section Xl, Subsection IWA provides the requirements for repair/replacement activities including the following:

o IWA-1320 specifies group classification criteria for applying the requirements of ASME Section Xl to various Code Classes of components. For example, the requirements in Subsection IWC apply to items classified as ASME Class 2 and the requirements in Subsection IWD apply to items classified as ASME Class 3.

r IWA-1400(g) requires Owners to possess or obtain an arrangement with an Authorized lnspection Agency (AlA).

o IWA-1400(k) requires Owners to perform repair/replacement activities in accordance with written programs and plans.

. IWA-1400(o) requires Owners to maintain documentation of a Quality Assurance Program in accordance with 10 CFR Part 50 or ASME NQA-1.

r IWA-4000 specifies requirements for performing ASME Section Xl repair/replacement activities on pressure-retaining items or their supports.

o IWA-621 1(d) and (e) specify Owner reporting responsibilities such as preparing Form NIS-2, Owner's Report for Repair/Replacement Activity.

I NUREG-0800, Section 3.6.2 provides a method for defining this scope of piping.

N152025055 Page 2 of 14 a

a a

IWA-6211(f) specifies when the Owner contracts a Repair/Replacement Organization to perform repair/replacement activities, the Owner shall require the Repair/Replacement Organization to provide a document certifying its repair/replacement activities.

IWA-6212 repeats the requirement for certification by a Repair/Replacement Organization and refers to Appendix T as an example.

IWA-6220 repeats the IWA-4150 requirement that a Repair/Replacement Plan be prepared for all repair/replacement activities, requires code data reports be completed, provides the required timing for completion of code data reports, identifies certification requirements for code data reports and includes the requirement for maintaining an index of Repair/Replacement plans.

IWA-6350 specifies that the following ASME Section Xl repair/replacement activity records must be retained by the Owner: evaluations required by IWA-4160 and IWA-4311, Repair/Replacement Programs and Plans, reconciliation documentation, and NIS-2 Forms.

a

4. Reason for Request

Nebraska Public Power District (NPPD) currently performs repairireplacement activities at Cooper Nuclear Station (CNS) in accordance with a deterministic Repair/Replacement Program based on the requirements of ASME Section Xl. Repair/Replacement Program requirements apply to procurement, design, fabrication, installation, examination, and pressure testing of items within the scope of ASME Section Xl. Repair/replacement activities include welding, brazing, defect removal, metal removal using thermal processes, rerating, and removing, adding, or modifying pressure-retaining items or supports. Repairireplacement activities are performed in accordance with NPPD's Quality Assurance (QA) Program and the ASME Section Xl Code. ln applying a deterministic approach to repairireplacement activities, a safety class (e.9., ASME Class 2 or 3) is assigned to every component within a system based on system function. The same treatment requirements are then applied to every component within the system without considering the risk associated with the probability that a specific item or component may or may not be functional at a time when needed.

Alternatively, a probabilistic approach to regulation enhances and extends the traditional deterministic approach by allowing consideration of a broader set of potential challenges to safety, providing a logical means for prioritizing these challenges based on safety significance, and allowing consideration of a broader set of resources to defend against these challenges. ln contrast to the deterministic approach, Probabilistic Risk Assessment (PRA) addresses credible initiating events by assessing the event frequency. Mitigating system reliability is then assessed, including the potential for common cause failures. The probabilistic approach to regulation is an extension and enhancement of traditional regulation by considering risk in a comprehensive manner. ln 2004, the Nuclear Regulatory Commission (NRC) promulgated 10 CFR 50.69 relating to risk-informed categorization and treatment of structures, systems, and components (SSCs) for nuclear power plants (Reference 8.2). This regulation permits power reactor licensees to implement an alternative regulatory framework with respect to "special treatment" (treatment beyond normal industrial practices) of low safety significant (LSS) SSCs. ln May 2006, the NRC staff issued Regulatory Guide (RG) 1.201, "Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to their Safety Significance," Revision 1 (Reference 8.3). RG 1.201 endorses a method, with conditions, for categorizing active SSCs

N152025055 Page 3 of 14 described in Nuclear Energy lnstitute (NEl) 00-04, "10 CFR 50.69 SSC Categorization Guideline," Revision 0 (Reference 8.4).

NPPD is not requesting NRC approvalto implement 10 CFR 50.69 in this request. lnstead, NPPD is proposing to implement the risk-informed categorization and treatment requirements of ASME Code Case N-752-1 when performing repair/replacement activities on Class 2 and 3 pressure-retaining items, or their associated supports, when SSCs have been categorized as LSS. Code Case N-752-1, which was approved by the ASME in April 2021, employs a comprehensive categorization process requiring input from both a PRA model and deterministic insights. This approach will enable evaluation, categorization, and implementation of alternative treatments for resolution of emergent issues in segments of piping having low safety significance.

Use of Code Case N-752-1 will also allow NPPD to identify and more clearly focus engineering, maintenance, and operations resources on critical components with high safety-significance, thus enabling NPPD to make more informed decisions and increase the safety of the plant.

5. Proposed Alternative and Basis for Use

Pursuant to 10 CFR 50.55a(z)(1), NPPD proposes to implement ASME Code Case N-752-1, without exception, as an alternative to the ASME Code requirements specified in Section 3 of this attachment. Code Case N-752-1 provides a process for determining the risk-informed categorization and treatment requirements for Class 2 and 3 pressure-retaining items or their associated supports. This requested alternative includes the categorization of passive SSCs (e.9., piping) and implementation of alternative special treatment activities limited to the repair/replacement activities for Class 2 and 3 pressure-retaining items or their associated supports. For components that have both active and passive functions, only the passive function will be categorized. The alternative treatments associated with Code Case N-752-1 will not be applied to the parts/components associated with the active function. Code Case N-752-1 may be applied on a system basis or on individual items within selected systems. Code Case N-752-1 does not apply to Class 1 items.

The use of this proposed alternative is requested on the basis that requirements in Code Case N-752-1 will provide an acceptable level of quality and safety.

5.1 Overview of Case N-752-1 Code Case N-752-1 provides for risk-informed categorization and treatment requirements for performing repair/replacement activities on Class 2 and 3 pressure-retaining items or their associated supports. Code Case N-752-1 is not applicable to the following:

o Class CC and MC items.

Piping within the break exclusion region [> NPS 4 (DN 100)] for high energy piping systems as defined by the Owner.

o That portion of the Class 2 feedwater system [> NPS 4 (DN 100)] of pressurized water reactors (PWRs) from the Steam Generator (SG), including the SG, to the outer containment isolation valve. This is not relevant to this request as CNS is a boiling water reactor (BWR) design.

N152025055 Page 4 of 14 The Code Case N-752-1 categorization methodology relies on the conditional core damage and large early release probabilities associated with postulated events. Safety significance is generally measured by the frequency and the consequence of the event. However, the risk-informed process categorizes components solely based on consequence, which measures the safety significance of the component given that it ruptures (component failure is assumed with a probability of 1.0). This approach is conservative compared to including the rupture frequency in the categorization as this approach will not allow the categorization of SSCs to be affected by any changes in frequency due to changes in treatment. lt additionally applies deterministic considerations (e.9., defense-in-depth, safety margins) in determining safety significance.

Additional details are provided Section 5.2 of this request.

The risk-informed process categorizes components as either high safety significant (HSS)or LSS. HSS components must continue to meet ASME Section Xl requirements for repair/replacement activities. LSS components are exempt from ASME Section Xl repair/replacement requirements and can be repaired/replaced in accordance with treatment requirements established by the Owner. The treatment requirements must provide reasonable confidence that each LSS item remains capable of performing its safety-related functions under design basis conditions. Component supports, if categorized, are assigned the same safety significance, HSS or LSS, as the highest passively ranked segment within the bounds of the associated analytical pipe stress model. The categorization and treatment requirements of Code Case N-752-1 are consistent with those in 10 CFR 50.69.

It should be noted that Code Case N-752, the predecessor of N-752-1, is based on Arkansas Nuclear One, Unit 2 (ANO-2) relief request ANO2-R&R-004, Revision 1, dated April 17,2007, as supplemented (Reference 8.5). The NRC approved that relief request on April 22,2009 (Reference 8.6). The ANO-2 relief request was developed to serve as an industry pilot for implementing a risk-informed repair/replacement process that included a risk-informed categorization process and treatment requirements. References 8.5 and 8.6 are also applicable to Code Case N-752-1 since the technical requirements of Code Case N-752 and Code Case N-752-1are equivalent.

5.2 Basis for Use The information below is provided as a basis or justification for NPPD's proposed alternative to implement the risk-informed categorization and treatment requirements of Code Case N-752-1 on Class 2 and 3 pressure-retaining items or their associated supports, as defined in Section 1 of this attachment.

A. Application to lndividual ltems Within a System The risk-informed methodology of Code Case N-752-1 may be applied on a system basis or on individual items within selected systems. Paragraph -1 100 of Code Case N-752-1 states: "This Case may be applied on a system basis, including all pressure retaining items and their associated supports, or on individual items categorized as low safety significant (LSS) within the selected systems." While this is the case, the risk-informed methodology is applied to the pressure boundary function of the individual components within the system. The risk-informed methodology contained in Code Case N-752-1 requires that the component's pressure boundary function be assumed to fail with a probability of 1.0, and all impacts caused by the loss of the pressure boundary function be identified. This would include identifying impacts of the

N152025055 Page 5 of 14 pressure boundary failure on the component under evaluation, identifying impacts of the pressure boundary failure of the component on the system in which the component resides, as well as identifying impacts of the pressure boundary failure of the component on any other plant SSC. This includes direct effects (e.g., loss of the flow path) of the component failure and indirect effects of the component failure (e.g.,

flooding, spray, pipe whip, loss of inventory). This comprehensive assessment of total plant impact caused by a postulated individual component failure is then used to determine the final consequence ranking. As such, the final consequence ranking of the individual component would be the same regardless of whether the entire system or only the individual component is subject to the risk-informed methodology.

B. Cateqorization Process The categorization process of Code Case N-752-1 is delineated in Appendix I of the Code Case. This categorization process is technically identical to the process approved by the NRC under Relief Request ANO2-R&R-004, Revision 1 (Reference 8.6), which, in turn, is based on founding principles in Electric Power Research lnstitute (EPRI) Report TR-112657, Revision B-A, "Revised Risk-lnformed lnservice lnspection Evaluation Procedure," and the categorization process of Code Case N-660, but with improvements and lessons learned from trial applications.

The Code Case N-752-1 risk-informed categorization evaluation is performed by an Owner-defined team that includes members with expertise in PRA, plant operations, system design, and safety or accident analysis. The risk-informed categorization process is based on the conditional consequence of failure, given that a postulated failure has occurred. A consequence category for each piping segment or component is determined via a failure modes and effects analysis (FMEA) and impact group assessment. The FMEA considers pressure boundary failure size, isolability of the break, indirect effects, initiating events, system impact or recovery, and system redundancy. The results of the FMEA for each system, or portion thereof, are partitioned into core damage impact groups based on postulated piping failures that (1) cause an initiating event, (2) disable a system/trainiloop without causing an initiating event, or (3) cause an initiating event and disable a system/trainiloop.

Failures are also evaluated for their importance relative to containment performance.

ln addition, the consequence rank is reviewed and adjusted to reflect the pressure boundary failure's impact on plant operation during shutdown and on the mitigation of external events. Credit may be taken for plant features and operator actions to the extent these would not be adversely affected by failure of the piping segment or component under consideration.

Consequence evaluation results are ranked as High, Medium, Low, or None (no change to base case). Piping segments/components ranked as High by the consequence evaluation process are considered HSS and require no further review.

Piping segments/components ranked as Medium, Low, or None by the consequence evaluation shall be determined to be HSS or LSS by evaluating the additional categorization considerations or conditions outlined in paragraph l-3.4.2(b) of Code Case N-752-1. lt any of these conditions are not met, then HSS shall be assigned. lf all conditions are met, then LSS may be assigned. lf LSS is assigned, the categorization process shall verify that there are sufficient margins to account for

N1S2025055 Page 6 of 14 uncertainty in the engineering analysis and supporting data. lf sufficient margin exists, then LSS should be assigned. lf sufficient margin does not exist, then HSS shall be assigned.

C. PRA Technical Adequacv Appendix l, Section l-3.2 of Code Case N-752-1 requires that the plant-specific PRA be assessed to confirm it is applicable to the safety significant categorization of Code Case N-752-1 including verification of assumptions on equipment reliability for equipment not within the scope of the ASME Code Case.

lnternal Events PRA The full scope peer review of the CNS full power internal events (FPIE) PRA model, including internal flooding, was conducted in 2008 in accordance with NEI 05-04 (Reference 8.21), RG 1.200, Revision 1 (Reference 8.7), and ASME/ANS PRA Standard RA-Sc-2007 (Reference 8.8).

An independent closure review of Finding and Observation (F&Os) using NEI methodology (References 8.14 and 8.15) was conducted in October 2022. All Finding-Level F&Os were verified closed with all applicable Supporting Requirements (SRs) from ASME/ANS PRA Standard RA-Sa-2009 (Reference 8.9) meeting Capability Category ll or greater.

CNS performed a self-assessment to determine whether the resolution of each Finding constituted maintenance or upgrade of the PRA, as defined in the ASME/ANS PRA Standard. The F&O lndependent Assessment Team concurred with CNS' conclusion that there were no PRA upgrades associated with the resolution of findings.

The CNS FPIE, internal flooding, and fire PRA models were used as part of adopting Technical Specification Task Force (TSTF) Traveler TSTF-425, Revision 3, "Relocate Surveillance Frequencies to Licensee Control-RITSTF [Risk-informed TSTF]

lnitiative 5b" (Reference 8.10). The NRC concluded that the technical reviews of the PRA were adequate and that the models could be used to support the evaluation of changes to surveillance frequencies within the Surveillance Frequency Control Program.

Fire PRA The full scope peer review of the CNS Fire PRA was documented in March 201 1. The review was conducted in accordance with NEI 07-12 (Reference 8.22), the ASME/ANS PRA Standard RA-Sa-2009 (Reference 8.9), and RG 1.200, Revision 2 (Reference 8.1 1).

A focused scope peer review was conducted in August 20241o review application of the high energy arc fault fire modeling methodology contained in NUREG-2262 (Reference 8.23).

lndependent F&O closure reviews were conducted in September 2024 and July 2025 using NEI methodology (References 8.14 and 8.15). All Finding-Level F&Os were

N1S2025055 PageT of 14 verified closed with all applicable SRs from the ASME/ANS Standard (Reference 8.9) meeting Capability Category ll or greater. Closure reviews were conducted in accordance with NEI 17-07 (Reference 8.24), the ASME/ANS PRA Standard, and RG 1.200, Revision 3 (Reference 8.12).

CNS performed a self-assessment to determine whether the resolution of each Finding constituted maintenance or upgrade of the PRA, as defined in the ASME/ANS PRA Standard. The F&O lndependent Assessment Team concurred with CNS'conclusion that there were no PRA upgrades associated with the resolution of findings.

The cNS fire PRA modelwas previously used in support of revising the Fire Protection Licensing Basis to adopt National Fire Protection Association (NFPA)

Standard 805. The NRC staff concluded that the PRA approach, methods, and data were acceptable and that the fire PRA model adequately supported the transition to NFPA 805 (Reference 8.13).

Conclusion ln conclusion, all PRA model Finding-Level F&Os are closed, and allapplicable SRs are met at Capability Category ll or greater. The closure of each Finding-Level F&O was also independently assessed. The CNS PRA models are of sufficient quality and level of detail to support the categorization process and have been subjected to a peer review process assessed against a standard or set of acceptance criteria that is endorsed by the NRC. Therefore, the PRA scope and technical adequacy are met for this application.

D. Feedback and Process Adiustment The NPPD process includes provisions for monitoring potential areas affecting the PRA models (e.9., due to changes in the plant, equipment performance, errors or limitations identified in the model, and industry operational experience) for assessing the risk impact of unincorporated changes, and for controlling the model and associated computer files. NPPD shall review changes to the plant, operational practices, applicable plant and industry operational experience, and, as appropriate, update the PRA and categorization and treatment processes. NPPD shall perform this review in a timely manner but no longer than once every two refueling outages.

E. Treatment Requirements for LSS ltems Code Case N-752-1 exempts LSS items, which have been categorized as LSS in accordance with the code case, from having to comply with the repair/replacement requirements of ASME Section Xl. Exempted ASME Code requirements for LSS items are outlined in Section 3, above. ln lieu of these requirements, Code Case N-752-1, Paragraph -1420 requires the Owner to define alternative treatment requirements which confirm with reasonable confidence that each LSS item remains capable of performing its safety-related functions under design basis conditions. These Owner treatment requirements must address or include all the provisions stipulated in Paragraphs -1420(a) through (j) of the code case. This approach to treatment is consistent with Risk-lnformed Safety Class (RISC)-3 treatment requirements specified in 10 CFR 50.69(dX2).

N1S2025055 Page 8 of 14 To comply with the above, NPPD intends to develop and/or revise existing procedures and documents to define treatment requirements for performing repair/replacement activities on LSS items in accordance with Code Case N-752-1. Defined treatment requirements will address design control, procurement, installation, configuration control, and corrective action. These procedures and documents will also include provisions wh ich address/im plement the followi ng req u irements:

1. Administrative controls for performing these repair/replacement activities.

2. The fracture toughness requirements of the original Construction Code and Owner's Requirements shall be met.

3. Changes in configuration, design, materials, fabrication, examination, and pressure testing requirements used in the repair/replacement activity shall be evaluated, as applicable, to ensure the structural integrity and leak tightness of the system are sufficient to support the design bases functional requirements of the system.

4. ltems used for repair/replacement activities shall meet the Owner's Requirements or revised Owner's Requirements as permitted by the licensing basis.

5. ltems used for repair/replacement activities shall meet the Construction Code to which the original item was constructed. Alternatively, items used for repair/replacement activities shall meet the technical requirements of a nationally recognized code, standard, or specification applicable to that item as permitted by the licensing basis.

6. The repair methods of nationally recognized post-construction codes and standards (e.9., ANSI/ASME PCC-2, API-653) applicable to the item may be used.

7. Performance of repairireplacement activities, and associated non-destructive examination (NDE), shall be in accordance with the Owner's Requirements and, as applicable, the Construction Code, or post-construction code or standard, selected for the repair/replacement activity. Alternative examination methods may be used as approved by the Owner. NDE personnel may be qualified in accordance with IWA-2300 in lieu of the Construction Code.

8. Pressure testing of the repair/replacement activity shall be performed in accordance with the requirements of the Construction Code selected for the repair/replacement activity or shall be established by the Owner.

9. Baseline examination (e.9., preservice examination) of the items affected by the repair/replacement activity, if required, shall be performed in accordance with requirements of the applicable program(s) specifying periodic inspection of items. See ltem 11 below for additional details.

10. lmplementation of Code Case N-752-1 does not negate or affect NPPD commitments to regulatory and enforcement authorities having jurisdiction at CNS.

11. Periodic lSl and lnservice Testing (lST) of LSS items at CNS will be performed as follows:

N1S2025055 Page 9 of 14 lSl of LSS pressure-retaining items or their associated supports will be performed as required and in accordance with the site's lSl program, which is implemented in accordance with 10 CFR 50.55a.

IST of pumps and valves that have been classified as LSS will be performed in accordance with the site's IST program implemented in accordance with 10 CFR 50.55a.

IST of snubbers that have been classified as LSS will be performed in accordance with the site's Snubber Testing program implemented in accordance with 10 CFR 50.55a.

lnspections of LSS items performed under other plant programs, such as Flow Accelerated Corrosion, will continue to be performed under those programs for the site.

12. Adverse conditions associated with LSS components will be entered into the NPPD corrective action program, which satisfies 10 CFR 50 Appendix B criteria for corrective action. Conditions that would prevent an LSS item from performing its safety-related function(s) under design basis conditions will be corrected in a timely manner. For significant conditions adverse to quality, measures will be taken to provide reasonable confidence that the cause of the condition is determined, and that actions are taken to preclude repetition.

Actions to correct adverse conditions associated with LSS items will be identified and addressed in accordance with NPPD's existing corrective action program. Finally, this approach to corrective action of LSS items is consistent with the NRC position on corrective action of RISC-3 SSCs as specified in 10 cFR 50.6e(dx2xii).

13. As permitted by Code Case N-752-1, NPPD intends to implement the exemption from IWA-1400(g) and IWA-4000 applicable to utilization of an AIA and Authorized Nuclear lnservice lnspector (ANll) when performing repair/replacement activities on LSS items. ln lieu of ANll inspection services, NPPD believes that its proposed treatment requirements, as described herein, provide reasonable confidence that LSS systems and items remain capable of performing their safety-related functions when repair/replacement activities are performed without the inspection services of an ANll. The exemption of ANll services is not unique to code case N-752-1. utilization of ANll inspection services is already exempt by ASME Section Xl for certain items and activities, such as small items (lWA-4131) and rotation of items for testing or preventative maintenance (lWA-4132). Finally, exemption of ANll services for this code case application is consistent with the NRC's position on risk-informed programs as specified in 10 CFR 50.69(bX1 Xv).

14. As permitted by code case N-752-1, NPPD intends to implement the eA Program exemption applicable to IWA-1400(o) and IWA-4000 when performing repair/replacement activities on LSS items. However, this code case exemption only applies if compliance with 10 CFR 50, Appendix B, or NQA-1 is not required by the NRC at the owner's facility. since 10 cFR 50 Appendix B is required at CNS, NPPD will update the Cooper Nuclear Station Quality Assurance Program for operation Policy Document (cNS eApD) for safety-related Class 2 and 3 SSCs identified as LSS in accordance with Code Case N-752-1 to not be required to meet the requirements of the CNS QAPD.

N1S2025055 Page 10 of 14 NPPD will develop alternative elements under the provisions of Appendix B describing treatment of these LSS SSCs to ensure continued capability and reliability of the design basis function. The procedures governing these treatment activities are classified as quality-related and are therefore, under the jurisdiction of 10 CFR 50, Appendix B. ln accordance with 10 CFR 50.5a(a)(3)(ii), NPPD does not intend to request prior approval of the CNS QAPD revision since the NRC previously determined that this type of change does not constitute a reduction in commitment in accordance with 10 CFR 50.54(a)(3)(ii), per the following.

. The NRC previously approved a change to the Entergy Quality Assurance Program Manual (Reference 8.16) in conjunction with a request for Arkansas Nuclear One to adopt ASME Code Case N-752 (References 8.17 and 8.18).

. The NRC's approval of the subject relief request for Duke Energy (Reference 8.19), stated, in part that "The NRC staff confirmed that the changes to the QAPD proposed by Duke Energy are consistent with the changes approved by the NRC staff to Entergy's QAPM as documented in the SE dated May 19, 2021, therefore, it is not considered a reduction in commitment in accordance with 10 CFR 50.54(a)(3)(ii)."

15. As permitted by Code Case N-752-1, NPPD intends to implement the exemptions from IWA-1400(k) and IWA-4000 applicable to repair/replacement programs and plans. ln lieu of these ASME Section Xl administrative controls, NPPD will establish Owner-defined administrative controls as required by paragraph -1420(a) of Code Case N-752-1. NPPD will utilize its existing work management processes for planning and documenting the performance of repair/replacement activities and supplement those process requirements as necessary to comply with Code Case N-752-1. These controls will ensure that repair/replacement activities on LSS items are performed in accordance with work instructions that have been appropriately planned, reviewed, and implemented. lt should also be noted that the exemption of Repair/Replacement Plans as required by IWA-1400(k) and IWA-4150 is not unique to Code Case N-752-1. Repair/Replacement Plans are already exempt by ASME Section Xl for certain items and activities such as small items (lWA-4131) and rotation of items for testing or preventative maintenance (lWA-4132). Finally, the exemption of ASME Section Xl programs and plans and the alternative use of Owner-defined administrative requirements on LSS items is consistent with the NRC's position on risk-informed programs as specified in 10 cFR 50.6e(b)(1)(v).

16. As permitted by Code Case N-752-1, NPPD intends to implement the exemption on IWA-4000 applicable to repair/replacement activities. Article IWA-4000 of the ASME Section Xl Code specifies administrative, technical, and programmatic requirements for performing repair/replacement activities on pressure-retaining items and their supports. As specified in IWA-41 10(b),

repair/replacement activities "include welding, brazing, defect removal, metal removal by thermal means, rerating, and removing, adding, and modifying items or systems. These requirements are applicable to procurement, design, fabrication, installation, examination, and pressure testing of items within the scope of this Division." ln lieu of these IWA-4000 requirements, NPPD will

NLS2025055 Page1lof14 perform repair/replacement activities on LSS items in accordance with an Owner defined program that complies with paragraph -1420 of Code Case N-752-1. The NPPD program will utilize existing processes, such as those appl icable to procurement, design, re-rati ng, fabrication, i nstal lation, modifications, welding, defect removal, metal removal by thermal processes and supplement those process requirements as necessary to comply with Code Case N-752-1. NPPD believes this program will ensure, with reasonable confidence, that LSS items remain capable of performing their safety-related functions under design basis conditions. Finally, the exemption of IWA-4000 requirements and the alternative use of Owner-defined treatment requirements for LSS items is consistent with the NRC's position on risk-informed programs as specified in 10 CFR 50.69(b)(t)(v) and (d)(2).

17. As permitted by Code Case N-752-1, NPPD intends to implement the documentation exem ptions on IWA-62 1 1 (d ), IWA-6 21 1 (e), and IWA-6350.

These ASME Section Xl paragraphs address preparation and retention of various ASME Section Xl records such as Form NIS-2, IWA-4160 verification of acceptabil ity evaluations, IWA-43 1 1 eval uations, Repair/Replacement Plans, and reconciliation documentation. ln lieu of these ASME Section Xl forms and evaluations, the following repair/replacement activity records shall be retained in accordance with NPPD's Owner-defined program for performing repair/replacement activities on LSS items.

. Repair/replacement activity documentation.

o Evaluations of LSS items that do not comply with requirements of the applicable Construction Code, standard, specification, and/or design specification. See also paragraph 5.2.E.12 above.

o Evaluations and documentation of design and configuration changes including material changes.

ln addition to the above, NPPD will also revise applicable CNS licensing basis documents (e.9., Updated Safety Analysis Report), as appropriate, to identify systems, subsystems, or individual items that have been categorized as LSS and address alternative treatment requirements. Changes to licensing basis documents will be performed in accordance with 10 CFR 50.59.

F. Conclusion Code Case N-752-1 specifies requirements for performing risk-informed categorization and treatment for performing repair/replacement activities on Class 2 and 3 pressure-retaining items or associated supports. The Code Case N-752-1 categorization process provides a comprehensive methodology for determining the safety significance of items - HSS or LSS. This categorization process is technically identical to that approved by the NRC under relief request ANO2-R&R-004, Revision 1 (References 8.5 and 8.6). Repair/replacement activities performed on items determined to be HSS or uncategorized items must continue to comply with the ASME Section Xl Code.

Repair/replacement activities performed on LSS items may comply with alternative treatment requirements that are defined by the Owner but must comply with all provisions of paragraph -1420 of Code Case N-752-1. NPPD's proposed treatment

N152025055 Page 12 of 14 requirements, as described herein, meet these criteria, and provide reasonable confidence that LSS systems and items remain capable of performing their safety-related functions under design basis conditions. Finally, categorization and treatment requirements of Code Case N-752-1 applicable to repair/replacement activities are consistent with NRC requirements specified in 10 CFR 50.69.

6. Duration of Proposed Alternative

The proposed alternative is being requested for use during CNS'sixth lSl interval, which begins on March 1, 2026, and ends on February 28, 2038. The sixth interval will be implemented as a 12-year interval per Code Case N-921 as conditioned by NRC RG 1.147, Revision 21.

7. Precedents

7.1 Entergy operations, lnc., Arkansas Nuclear one, Units 1 and 2, Request for Relief No. EN-20-RR-001, May 27,2020 (ML20148M343), approved May 19,2021 (ML211188039)

Duke Energy oconee Nuclear station, Units 1,2, and 3, Request for Relief Number RA-22-0174, submitted July 27, 2022 (ML22208A031), and approved December 13, 2023 (ML23262A967) st. Lucie Units 1 and 2, seabrook station, Point Beach Units 1 and 2, Fleet Relief Request 23-01, submitted March 15,2023 (ML23074A155), approved June 1 2, 2024 (ML24149A286) 7.2

8. References 8.1 7.3 8.2 8.3 8.4 American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section Xl (ASME Section Xl), 2019 Edition "Risk-informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors," 69 FR 68008, 10 CFR 50.69, November 22,20e4 NRC Regulatory Guide 1.201 (For Trial Use), Revision 1, "Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance," May 2006.

Nuclear Energy lnstitute (NEl) 00-04, "10 CFR 50.69 SSC Categorization Guideline,"

Revision 0, July 2005 (ML052910035)

Entergy Letter to NRC, "Request for Alternative ANO2-R&R-004, Revision 1, Request to Use Risk-lnformed Safety Classification and Treatment for Repair / Replacement Activities in Class 2 and 3 Moderate Energy Systems," April 1 7, 2OO7 (ML071150108) as supplemented by letters dated August 6,2007 (ML072220160), February 20,2008 (M10805201 86), and January 12, 2009 (M1090120620)

NRC Letter to Entergy, "Arkansas Nuclear one, Unit 2 - Approval of Request for Alternative ANO2-R&R-004, Revision 1, Request to Use Risk-lnformed safety Classification and Treatment for Repair/Replacement Activities in Class 2 and 3 Moderate and High Energy Systems," April22,2009 (ML090930246) 8.5 8.6

N1S2025055 Page 13 of 14 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19 8.20 8.21 NRC Regulatory Guide 1.200, Revision 1, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-lnformed Activities,"

January 2007 (M 107 0240001)

American Society of Mechanical Engineers (ASME) PRA Standard ASME M-Sc-2007 Addenda to, "ASME RA-S-2002 Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications," July 2007 American Society of Mechanical Engineers (ASME)/American Nuclear Society (ANS)

RA-Sa-2009, "Addenda to ASME RA-S-2008, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications," February 2009 NRC Letter to NPPD, "Cooper Nuclear Station - lssuance of Amendment Re: Adoption of Technical Specification Task Force Traveler TSTF-425, Revision 3, March 31,2017 (M1170614050)

NRC Regulatory Guide 1.200, Revision 2, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-lnformed Activities "

March 2009 (M109041 001 4)

NRC Regulatory Guide 1.200, Revision 3, "Acceptability of Probabilistic Risk Assessment Results for Risk-lnformed Activities," December 2020 (ML202388871)

NRC Letter to NPPD, "Cooper Nuclear Station - lssuance of Amendment Regarding Transition to a Risk-lnformed, Performance-Based Fire Protection Program in Accordance with 10 CFR 50.48(c)," April 29, 2014 (ML140554023)

Final Revision of Appendix X to NEI 05-04107-12112-16, "close out of Facts and Observations (F&Os)," February 2017 (ML17086A431 )

Letter from J. Giitter and M.J. Ross-Lee (NRC) to G. Krueger (NEl), "U.S. Nuclear Regulatory Commission Acceptance on Nuclear Energy lnstitute Appendix X To Guidance 05-04, 07-12, And 12-13, Close-Out of Facts And Observations (F&Os),"

May 2017 (M117079A427)

NRC Letter to Entergy, "Arkansas Nuclear One, Units 1 and 2 - Request for Approval of Change to the Entergy Quality Assurance Program Manual," May 19,2Q21 (M121132A279)

Entergy letter to NRC, "Relief Request Number EN-20-RR-001 - Proposed Alternative to Use ASME Code Case N-752, Risk-lnformed Categorization and Treatment for Repair/ReplacementActivities in Class 2and 3 Systems, Section Xl, Division 1," May 27, 2020 (M120148M343)

NRC Letter to Entergy, "Arkansas Nuclear One, Units 1 and 2 - Approval of Request for Alternative from Certain Requirements of The American Society of Mechanical Engineers Boiler and Pressure Vessel Code," May 19,2021(ML211188039)

NRC Letter to Duke Energy, "Oconee Nuclear Station, Units 1,2, and 3 - RE:

Authorization of Alternative to use RR-22-0174, Risk-lnformed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems Section Xl, Division 1," December 13, 2023 (ML23262A967)

NRC Regulatory Guide 1.147, Revision 21, "lnservice lnspection Code Case Acceptability, ASME Section Xl, Division 1," March 2024 NEI 05-04 Revision 2, "Process for Performing lnternal Events PRA Peer Reviews Using the ASME/ANS PRA Standard," November 2008.

N1S2025055 Page 14 of 14 8.22 8.23 8.24 NEI 07-12 Revision 1, "Fire Probabilistic Risk Assessment (FPRA) Peer Review Process Guidelines," June 2010.

NUREG-2262, "High Energy Arc Fault Frequency and Consequence Modeling", April 2023.

NEI 17-07 Revision 2, "Performance of PRA Peer Reviews Using the ASME/ANS PRA Standard," August 2019.