RA-24-0291, Duke Energy - Request for Exemptions from 10 CFR 50.55a(a)(3)(ii), Which Incorporates by Reference Regulatory Guide 1.147, Revision 21, for Code Case N-921, and 10 CFR 50.55a(y)

Duke Energy - Request for Exemptions from 10 CFR 50.55a(a)(3)(ii), Which Incorporates by Reference Regulatory Guide 1.147, Revision 21, for Code Case N-921, and 10 CFR 50.55a(y)

ML25128A041
Person / Time
Site:	Oconee, Robinson, McGuire
Issue date:	05/08/2025
From:	Ellis K Duke Energy, Duke Energy Carolinas, Progress Energy Carolinas
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RA-24-0291
Download: ML25128A041 (1)

Text

Kevin M. Ellis General Manager Nuclear Regulatory Affairs, Policy &

Emergency Preparedness Duke Energy 13225 Hagers Ferry Rd., MG011E Huntersville, NC 28078 843-951-1329 Kevin.Ellis@duke-energy.com 10 CFR 50.12 RA-24-0291 May 8, 2025 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 H.B. Robinson Steam Electric Plant, Unit 2 Docket No. 50-261 / Renewed License No. DPR-23 McGuire Nuclear Station, Unit 1 Docket No. 50-369 / Renewed License No. NPF-9 and NPF-17 Oconee Nuclear Station, Units 1, 2, and 3 Docket Nos. 50-269, 50-270, and 50-287 Subsequent Renewed License Nos. DPR-38, DPR-47, and DPR-55

Subject:

Request for Exemptions from 10 CFR 50.55a(a)(3)(ii), which incorporates by reference Regulatory Guide 1.147, Revision 21, for Code Case N-921, and 10 CFR 50.55a(y)

In accordance with 10 CFR 50.12, Specific exemptions, Duke Energy Carolinas, LLC, and Duke Energy Progress, LLC, collectively referred henceforth as Duke Energy, is requesting U.S. Nuclear Regulatory Commission (NRC) approval of exemptions from 10 CFR 50.55a(a)(3)(ii), which incorporates by reference Regulatory Guide 1.147, Revision 21, Table 2, including a condition that limits the use of the ASME Society of Mechanical Engineers (ASME) Code Case N-921 to the beginning of the Inservice Inspection interval. Duke Energys exemption request also extends to the definition of Inservice Inspection (ISI) interval of 10 CFR 50.55a(y). These exemptions are being submitted at the recommendation of the NRC staff, as documented in the Final Rule noticed in the Federal Register adopting Code Case N-921. Duke Energy requests exemptions for H.B. Robinson Steam Electric Plant, Unit 2 (RNP), McGuire Nuclear Station, Unit 1 (MNS), and Oconee Nuclear Station, Units 1, 2, and 3 (ONS), because Code Case N-921 was not applied at the beginning of the current ISI interval that started prior to issuance of Regulatory Guide 1.147, Revision 21. Exemptions are requested for the remainder of each units extended ISI interval.

The exemption request is provided in the Enclosure to this letter. An assessment of previously NRC-authorized alternatives (i.e., relief requests) is provided in Attachments 1, 2, and 3 for RNP, MNS, and ONS.

No regulatory commitments are contained in this submittal.

Duke Energy requests NRC staff review and approval of this request by November 28, 2025.

r. DUKE

• ~ ENERGY

U.S. Nuclear Regulatory Commission RA-24-0291 Page 2 If there are any questions or if additional information is needed, please contact Mr. Ryan Treadway, Director - Nuclear Fleet Licensing, at 980-373-5873.

Sincerely, Kevin M. Ellis General Manager - Nuclear Regulatory Affairs, Policy & Emergency Preparedness

Enclosure:

Request for Exemptions from 10 CFR 50.55a(a)(3)(ii), incorporating by reference Regulatory Guide 1.147, Revision 21, Condition (2) for Code Case N-921, and 10 CFR 50.55a(y) cc:

Regional Administrator - NRC Region II NRC Senior Resident Inspector - H.B. Robinson Steam Electric Plant NRC Senior Resident Inspector - McGuire Nuclear Station NRC Senior Resident Inspector - Oconee Nuclear Station NRC Project Manager - H.B. Robinson Steam Electric Plant NRC Project Manager - McGuire Nuclear Station NRC Project Manager - Oconee Nuclear Station NRC Project Manager - Duke Energy Fleet

Enclosure Duke Energy Carolinas, LLC and Duke Energy Progress, LLC (Duke Energy)

H.B. Robinson Steam Electric Plant, Unit 2 McGuire Nuclear Station, Unit 1 Oconee Nuclear Station, Units 1, 2, & 3 Request for Exemptions from 10 CFR 50.55a(a)(3)(ii), incorporating by reference Regulatory Guide 1.147, Revision 21, Condition (2) for Code Case N-921, and 10 CFR 50.55a(y)

RA-24-0291 Enclosure Page 2 I.

Description In accordance with 10 CFR 50.12, Specific exemptions, Duke Energy Carolinas, LLC and Duke Energy Progress, LLC, collectively referred henceforth as Duke Energy, is requesting NRC approval of exemptions from 10 CFR 50.55a(y) and 10 CFR 50.55a(a)(3)(ii), which incorporates by reference Code Case N-921 from Regulatory Guide 1.147, Revision 21. The exemption request, if granted, would allow H.B.

Robinson Steam Electric Plant, Unit 2 (RNP), McGuire Nuclear Station, Unit 1 (MNS), and Oconee Nuclear Station, Units 1, 2, and 3 (ONS) to implement American Society of Mechanical Engineers (ASME) Code Case N-921 during the current Inservice Inspection (ISI) interval.

10 CFR 50.55a(y) defines the ISI interval as 10 years by reference to IWA-2431.

Regulatory Guide 1.147, Revision 21, Table 2, condition (2) limits initial implementation of ASME Code Case N-921 to the beginning of an ISI interval. 10 CFR 50.55a(a)(3)(ii) approves NRC Regulatory Guide 1.147, Revision 21, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, issued March 2024, to be incorporated by reference into the regulation. Exemptions are requested for RNP, MNS, and ONS because Code Case N-921 was not applied at the beginning of the current ISI interval for those units.

Exemptions are requested for the remainder of each plants current ISI interval. The proposed exemption request does not impact the Inservice Testing (IST) or snubber programs which are implemented as part of the ASME Operation and Maintenance Code.

The technical justification that supports implementing Code Case N-921 following the start of the ISI interval is provided in the following sections.

II.

Background.

On July 17, 2024, the NRC issued a final rule that included new approved code cases and update frequencies (Reference 1). Amongst the modifications in the Final Rule were revisions to 10 CFR 50.55a(a)(3)(ii), which approves NRC Regulatory Guide 1.147, Revision 21, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, issued March 2024 to be incorporated by reference into the regulation. Regulatory Guide 1.147, Revision 21, conditionally approved Code Case N-921. Code Case N-921 establishes a 12-year ISI interval for Inservice Inspection programs. The marginal extension from a 10-year to 12-year interval supports a minimum of two refueling outages per period and allows levelized distribution of examinations and tests across all inspection periods.

Code Case N-921 was approved subject to the following conditions:

(1) The licensees code of record for the ISI program must be the 2017 Edition of Section XI or later, in order to apply this code case.

(2) This code case can only be implemented at the beginning of an ISI interval as part of a routine update of the ISI program.

(3) This code case cannot be used to modify the examination schedules for augmented inspections under 10 CFR 50.55a(g)(6)(ii).

RA-24-0291 Enclosure Page 3 (4) The exceptions of IWB-2411(a), IWC-2411(a), and IWD-2411(a) also apply to Table 1 of this code case.

Condition (2) on N-921 was added to NRC Regulatory Guide 1.147, Revision 21 in response to an anonymous public comment (ML23235A158). The specific comment that led to the inclusion of Condition (2) is provided below for reference (ML23291A328).

B-6 Code Case N-921 Implementation Comment Summary B-6: A commenter suggested that the NRC add a condition to require implementation of Code Case N-921 at the beginning of an ISI interval. The commenter stated that implementing the code case mid-ISI interval could lead to extra burden for the NRC and the industry. Specifically, existing alternatives would likely need to be reauthorized by the NRC. The commenter suggested that the NRC should add a condition requiring that Code Case N-921 only be implemented at the start of a new interval, to eliminate these requests. The commenter stated that NRCs regulatory analysis did not provide or address the additional costs associated with updating to the code cases mid-interval for licensees submitting new alternative requests.

(13-2, 13-3)

NRC Response:

The NRC agrees with the commenter and has added a condition to only allow implementation of Code Case N-921 to occur at the beginning of an ISI interval, rather than allowing implementation during a mid-ISI interval. The NRC agrees that mid-ISI interval implementation of Code Case N-921 would create a significant burden for both the NRC and licensees because of the ongoing schedule for ISI activities and the need to resubmit requests for alternatives authorized based on a 10-year ISI interval. The NRC notes that the ASME BPV Code currently allows a 1-year extension of the 10-year ISI interval with certain conditions, which makes the necessary burden to achieve an extra 1-year ISI interval extension to be of questionable resource value. Licensees wishing to implement Code Case N-921 during a mid-ISI interval should submit an exemption request in accordance with 10 CFR 50.12, Specific exemptions, and should review all NRC-authorized alternative requests to determine whether they need to be resubmitted to the NRC for review and authorization.

As a result of this comment, the NRC added a condition to RG 1.147, Revision 21, to only allow implementation of Code Case N-921 at the beginning of a new ISI interval.

The NRC Final Rule noticed in the Federal Register reiterated the rational underlying N-921 Condition 2 (Reference 1):

There are complications associated with extending the ISI interval mid-interval. For instance, licensees wanting to extend the ISI interval mid-interval would need to evaluate all NRC-approved alternatives to determine if they should be resubmitted, especially considering that NRC may have granted the alternative assuming a 10-year ISI interval. Further, Code Case N-921 specifies requirements in terms of three 4-year periods, so licensees would need to reconcile their inspection schedules accordingly. Therefore, this final rule specifies that Code Case N-921 can only be implemented following a routine update of the ISI program (i.e., cannot be implemented mid-interval) and requires the licensees ISI code of record to be the 2017 Edition, or later, of the BPV Code.

RA-24-0291 Enclosure Page 4 In summary, the NRC identified two distinct concerns with allowing mid-interval implementation of Code Case N-921:

licensees would need to evaluate all NRC-approved alternatives to determine if they should be resubmitted, and licensees would need to reconcile their inspection schedules to conform with the three 4-year periods specified in Code Case N-921.

Additionally, 10 CFR 50.55a(y) was also revised, adding a definition of Inservice Inspection (ISI) interval to state the inspection interval described in Article IWA-2432 of ASME BPV Code,Section XI, 1989 Edition with 1991 Addenda through the 2008 Addenda, or Article IWA-2431 of ASME BPV Code,Section XI, 2009 Addenda and later.

This definition creates an inconsistency with application of Code Case N-921.

The current ISI intervals for RNP, MNS, and ONS started in February 2023, December 2021, and July 2024, respectively, prior to the incorporation of Regulatory Guide 1.147, Revision 21 into the regulation. Duke Energy had intended to utilize Code Case N-921 once incorporated into the regulation and took specific actions during the interval updates to facilitate use of the case. The addition of Condition 2 after the public comment period prevented Duke Energy from utilizing Code Case N-921.

Implementation of Code Case N-921 will allow RNP, MNS, and ONS to utilize the Code Case without significant burden to both the NRC staff and Duke Energy personnel, and also allow for a more efficient distribution of examinations throughout the remainder of the extended interval. Currently ASME Section XI divides the 10-year inspection interval into (3) periods (typically a 3-4-3 year breakdown for periods). Code Case N-921 allows plants to establish four-year periods (4-4-4 year breakdown) over the course of a 12-year inspection interval. This change supports plants that have transitioned or planning to transition from 18-month refueling cycles to 24-month refueling cycles. Additionally, this ensures each inspection period during a 12-year interval will have at least two refueling outages (2-2-2 format). Since each Unit is early in the current interval, the initial implementation of the Code Case will result in improved distribution of exams. Specific period dates and proposed interval end dates with outages are shown in Table 1. All other conditions associated with Code Case N-921 as specified in Regulatory Guide 1.147, Revision 21, Table 2 remain applicable.

RA-24-0291 Enclosure Page 5 Table 1 Plant/Unit(s)

Interval(1)

ASME Section XI Code Edition Current Interval Start Date Current Interval End Date Proposed 12-yr Interval End Date(2)

H.B. Robinson Steam Electric Plant (RNP), Unit 2 Sixth ISI(3) 2017 Edition 02/19/2023 02/18/2033 02/18/2035 McGuire Nuclear Station (MNS), Unit 1 Fifth ISI(4) 2019 Edition(5,6) 12/01/2021 11/30/2031 11/30/2033 Oconee Nuclear Station (ONS), Units 1, 2, & 3 Sixth ISI Fourth CISI 2019 Edition 07/15/2024 07/14/2034 07/14/2036 Notes:

1. ISI - Inservice Inspection; CISI - Containment Inservice Inspection

2. The Interval End Date is subject to change in accordance with -2430(c)(1) of Code Case N-921.

3. The 3rd Ten-Year CISI for RNP is not in scope for this request.

4. The 4th Ten-Year CISI for MNS Units 1 and 2 is not in scope for this request.

5. ISI Examinations and Pressure Testing performed in the 1st Period are in accordance with Section XI, 2007 Edition with 2008 Addenda per Request RA-20-0031 (Reference 10). MNS1 transitioned to the 2019 Edition for the remainder of the 5th Interval (Periods 2 and 3) per Request RA-20-0031.

6. Application of Code Case N-921 is only required for MNS Unit 1 in order to align the start of the subsequent 6th inspection interval with MNS Unit 2. MNS Unit 2 will remain on a nominal 10-year inspection interval per ASME Section XI Code requirements, while MNS Unit 1 invokes a nominal 12-year inspection interval per Code Case N-921. This aligns the 6th interval start dates for both units and precludes submittal of future requests similar to Reference 10.

III.

Basis for Approval of Exemption Request In accordance with 10 CFR 50.12, the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR Part 50 which are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense and security. The Commission will not consider granting an exemption unless special circumstances are present.

As discussed below, this exemption request satisfies the provisions of 10 CFR 50.12.

a) Authorized by law (10 CFR 50.12(a)(1))

These exemptions would allow Duke Energy to implement ASME Code Case N-921 at RNP, MNS, and ONS during current ISI intervals. The NRC acknowledged the appropriateness of submitting an exemption in its response to public comments noted above. Granting the proposed exemptions will not result in a violation of the Atomic Energy Act of 1954, as amended, and will not present an undue risk to the public health and safety and is consistent with the common defense and security. Therefore, the exemptions are authorized by law.

b) Will not present an undue risk to public health and safety (10 CFR 50.12(a)(1))

The underlying purpose of condition (2) on Code Case N-921 was to prevent significant burden to the NRC and the Licensee regarding ISI program implementation,

RA-24-0291 Enclosure Page 6 examination schedule revisions and re-submittal of previously approved Relief Requests. Any potential burden associated with implementing Code Case N-921 impacts time and resources for managing the ISI program and does not impact public health and safety. Therefore, these exemptions will not present an undue risk to public health and safety.

c) Consistent with the common defense and security (10 CFR 50.12(a)(1))

The proposed exemptions would allow Duke Energy to implement ASME Code Case N-921 at RNP, MNS, and ONS during the current ISI intervals and has no relation to security. The proposed exemptions will not adversely affect Duke Energys cability to physically secure the sites and facilities and to protect special nuclear material.

Therefore, the common defense and security would not be affected by these exemptions.

d) Special circumstances are present (10 CFR 50.12(a)(2))

In accordance with 10 CFR 50.12(a)(2), the NRC will not consider granting an exemption to its regulations unless special circumstances are present.

10 CFR 50.12(a)(2)(ii) Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule.

Generally speaking, the purpose of the 2024 rulemaking adopting the current provisions of 10 CFR 50.55a(a)(3)(ii) is for the NRC to identify new, revised, and reaffirmed ASME code cases that the NRC has determined are acceptable for use as voluntary alternatives to compliance with certain provisions of the ASME BPV Code currently incorporated by reference into the NRCs regulations. Specifically with respect to Section 50.55a(a)(3)(ii), the purpose was to incorporate by reference Regulatory Guide 1.147, Revision 21, which in turn conditionally approves Code Case N-921. The NRC Final Rule noticed in the Federal Register adopting 10 CFR 50.55a(a)(3)(ii) states that [t]he inservice inspection interval and the code of record update interval should be synchronized to promote order and predictability in licensee inservice inspection programs. (Reference 1)

As stated above, the NRCs conditional approval of Code Case N-921 includes a condition that This code case can only be implemented at the beginning of an ISI interval as part of a routine update of the ISI program with the NRC explaining that that mid-ISI interval implementation of Code Case N-921 would create a significant burden for both the NRC and licensees because of the ongoing schedule for ISI activities and the need to resubmit requests for alternatives authorized based on a 10-year ISI interval.

Implementation of Code Case N-921 following the start of the current ISI interval does not inhibit the ability of Duke Energy to comply with code required periodic distribution requirements and allows for a more efficient distribution of examinations and tests throughout the remainder of the extended interval. Currently ASME Section XI divides the 10-year ISI interval into (3) periods, with allowable adjustments described in IWA-2430. Code Case N-921 allows plants to establish consistent four-year periods over the course of a 12-year ISI interval. This will ensure that each inspection period during

RA-24-0291 Enclosure Page 7 the 12-year interval will include at least two refueling outages. During the most recent ISI interval update for RNP and ONS, Duke Energy established the periods as a 4-4-2 year breakdown so the additional 2 years allowed by Code Case N-921 could be added to the third period. Application of Code Case N-921 was planned during the most recent ISI interval update for MNS Unit 1 in order to align the start of the subsequent 6th inspection interval with MNS Unit 2. The specific period dates and proposed interval dates, with outages, are shown for each Unit in Tables 2 through 6 below.

Table 2: H.B. Robinson Unit 2 - Sixth ISI Interval Interval Periods Outages Start Date to End Date Start Date to End Date Outage Numbers 6th ISI Interval 02/19/2023 to 02/18/2033 (02/18/2035)*

1st 02/19/2023 to 02/18/2027 R2R34 Fall 2024 R2R35 Fall 2026 2nd 02/19/2027 to 02/18/2031 R2R36 Fall 2028 R2R37 Fall 2030 3rd 02/19/2031 to 02/18/2033 (02/18/2035)*

R2R38 Fall 2032 R2R39**

Fall 2034 Notes:

• Proposed interval end date for implementation of a 12-yr interval via Code Case N-921.

• • Proposed last outage for implementation of a 12-yr interval via Code Case N-921.

RA-24-0291 Enclosure Page 8 Table 3: McGuire Unit 1 - Fifth ISI Interval Interval Periods Outages Start Date to End Date Start Date to End Date Outage Numbers 5th ISI Interval 12/01/2021 to 11/30/2031 (11/30/2033)*

1st 12/01/2021 to 11/30/2024 M1R28 Spring 2022 M1R29 Fall 2023 2nd 12/01/2024 to 11/30/2028 M1R30 Spring 2025 M1R31 Fall 2026 M1R32 Spring 2028 3rd 12/01/2028 to 11/30/2031 (11/30/2033)*

M1R33 Fall 2029 M1R34 Spring 2031 M1R35**

Fall 2033 Notes:

• Proposed interval end date for implementation of a 12-yr interval via Code Case N-921.

• • Proposed last outage for implementation of a 12-yr interval via Code Case N-921.

Table 4: Oconee Unit 1 - Sixth ISI Interval, Fourth CISI Interval Interval Periods Outages Start Date to End Date Start Date to End Date Outage Numbers 6th ISI Interval 4th CISI Interval 07/15/2024 to 07/14/2034 (07/14/2036)*

1st 07/15/2024 to 07/14/2028 O1R33 Fall 2024 O1R34 Fall 2026 2nd 07/15/2028 to 07/14/2032 O1R35 Fall 2028 O1R36 Fall 2030 3rd 07/15/2032 to 07/14/2034 (07/14/2036)*

O1R37 Fall 2032 O1R38**

Fall 2034 Notes:

• Proposed interval end date for implementation of a 12-yr interval via Code Case N-921.

• • Proposed last outage for implementation of a 12-yr interval via Code Case N-921.

RA-24-0291 Enclosure Page 9 Table 5: Oconee Unit 2 - Sixth ISI Interval, Fourth CISI Interval Interval Periods Outages Start Date to End Date Start Date to End Date Outage Numbers 6th ISI Interval 4th CISI Interval 07/15/2024 to 07/14/2034 (07/14/2036)*

1st 07/15/2024 to 07/14/2028 O2R32 Fall 2025 O2R33 Fall 2027 2nd 07/15/2028 to 07/14/2032 O2R34 Fall 2029 O2R35 Fall 2031 3rd 07/15/2032 to 07/14/2034 (07/14/2036)*

O2R36 Fall 2033 O2R37**

Fall 2035 Notes:

• Proposed interval end date for implementation of a 12-yr interval via Code Case N-921.

• • Proposed last outage for implementation of a 12-yr interval via Code Case N-921.

Table 6: Oconee Unit 3 - Sixth ISI Interval, Fourth CISI Interval Interval Periods Outages Start Date to End Date Start Date to End Date Outage Numbers 6th ISI Interval 4th CISI Interval 07/15/2024 to 07/14/2034 (07/14/2036)*

1st 07/15/2024 to 07/14/2028 O3R33 Spring 2026 O3R34 Spring 2028 2nd 07/15/2028 to 07/14/2032 O3R35 Spring 2030 O3R36 Spring 2032 3rd 07/15/2032 to 07/14/2034 (07/14/2036)*

O3R37 Spring 2034 O3R38**

Spring 2036 Notes:

• Proposed interval end date for implementation of a 12-yr interval via Code Case N-921.

• • Proposed last outage for implementation of a 12-yr interval via Code Case N-921.

As outlined above, the NRC expressed concerns that allowing mid-cycle implementation of Code Case N-921 would result in a significant burden and identified two specific concerns underlying this assertion:

RA-24-0291 Enclosure Page 10 licensees would need to evaluate all NRC-approved alternatives to determine if they should be resubmitted, and licensees would need to reconcile their inspection schedules to conform with the three 4-year periods specified in Code Case N-921.

With respect to the need to evaluate previously approved alternates that were based on a 10-year ISI interval, this would not be a significant burden and in fact Duke Energy has already performed this evaluation. Duke Energy performed a review of all previously authorized alternatives (relief requests) for RNP, MNS, and ONS and assessed the impact of extending the interval by 2 years to implement Code Case N-921 on the technical basis supporting each alternative. The results of this assessment determined that there is no impact to the technical basis supporting any of the previously approved alternatives. The full assessment of each previously approved alternative and impact of transitioning to a 12-year interval on the supporting technical basis is included in Attachments 1, 2, and 3.

The proposed exemptions will allow implementation of Code Case N-921 for the remainder of the current ISI interval for the plants listed in Table 1. All other conditions associated with Code Case N-921 apply as specified in Regulatory Guide 1.147, Revision 21. The proposed exemptions do not include an alternative to the ASME Section XI requirements to distribute examinations among the three inspection periods and there is no impact on the technical basis supporting previously approved relief requests applicable to the current ISI interval as provided in Attachments 1, 2, and 3.

The second concern regarding significant burden resulting from licensees needing to reconcile inspection schedules to conform with three four-year periods as specified in Code Case N-921 does not pose a challenge. Duke Energy revises the ISI examination schedule periodically. Reasons for revising the ISI examination schedule periodically include, but are not limited to, dose, availability of examination equipment and personnel, availability of personnel for required support tasks (e.g. insulation, scaffold, weld preparation), outage schedules, outage duration, changes in operating strategy, plant modifications, risk-informed periodic updates, etc. Maintaining the ISI examination schedule, including periodic changes, is core business for ISI program owners. Therefore, implementation of Code Case N-921 after the beginning of the interval is not significantly burdensome. As previously mentioned, during the most recent ISI interval updates Duke Energy took specific actions in anticipation of implementation of Code Case N-921 in the new intervals. This includes revision of the period start and end dates and adjusting examination schedules accordingly.

The special circumstance of 10 CFR 50.12(a)(2)(ii) is applicable since the concerns identified by the NRC in establishing Condition 2 for Code Case N-921 do not pose challenges to Duke Energy, or can be easily mitigated, and the purpose of the rule would continue to be achieved when implementing Code Case N-921 during the current ISI intervals at RNP, ONS and MNS.

10 CFR 50.12(a)(2)(iii) Compliance would result in undue hardship or other costs that are significantly in excess of those contemplated when the regulation was adopted, or that are significantly in excess of those incurred by others similarly situated.

RA-24-0291 Enclosure Page 11 The Commission has explained that the application of Criterion iii, undue hardship, is narrow. As the Commission stated in the 1985 rule adopting the current exemption criteria, this special circumstance was intended to provide equitable treatment to applicants or licensees who, because of some unusual circumstance, are affected in a manner different than that of other similarly situated licensees or applicants.

(Reference 3) Duke Energy would be subjected to an undue hardship as a result of the application of Condition 2 to Code Case N-921. Specifically, limiting Duke Energy from implementing Code Case N-921 for RNP, MNS, and ONS would result in inequitable treatment since the basis does not pose any challenges to these facilities. As explained above, none of the concerns regarding mid-interval adoption of Code Case N-921 that underlie Condition 2 pose any challenges to Duke Energy or can be easily mitigated. Therefore, it would be inequitable to preclude Duke Energys capability to implement the useful improvements to ISI inspection schedules otherwise permitted by Code Case N-921.

Therefore, compliance with Section 50.55a(a)(3)(ii) and the related condition imposed on the implementation of Code Case N-921 would result in undue hardship and Special Circumstance 50.12(a)(2)(iii) is present.

10 CFR 50.12(a)(2)(vi) There is present any other material circumstance not considered when the regulation was adopted for which it would be in the public interest to grant an exemption.

There are material circumstances that are present and not considered when the NRC modified 10 CFR 50.55a(a)(3)(ii) and adopted the related Condition 2 for implementation of Code Case N-921. Specifically, the NRC adopted Condition 2 based on a single comment without an opportunity for the industry to provide additional input on whether, in fact, mid-interval implementation of Code Case N-921 would result in the significant burden asserted. Had such input been provided, the NRC may have understood a mid-interval implementation of Code Case N-921 would not create the significant burden that it anticipated. As explained in this exemption request, the concerns underlying this condition do not pose any challenges for Duke Energy.

Therefore, there are material circumstances that are present and not considered when the NRC modified 10 CFR 50.55a(a)(3)(ii) and adopted the related Condition 2 for implementation of Code Case N-921 and Special Circumstance 50.12(a)(2)(vi) is present.

IV.

Environmental Consideration Duke Energy has determined that the requested exemptions meet the categorical exclusion provision in 10 CFR 51.22(c)(25), as the requested licensing action is an exemption from the requirements of the Commission's regulation and (i) there is no significant hazards consideration; (ii) there is no significant changes in the types or significant increase in the amounts of any effluents that may be released offsite; (iii) there is no significant increase in individual or cumulative public or occupational radiation exposure; (iv) there is no significant construction impact; (v) there is no significant increase in the potential for or consequences from radiological accidents; and (vi) the requirements from which an exemption is sought involve inspections, scheduling and administrative requirements.

RA-24-0291 Enclosure Page 12 Therefore, in accordance with 10 CFR 51.22(b), no environmental assessment or environmental impact statement needs to be prepared in connection with the proposed exemption request.

V.

Conclusion Based on current ISI examination and testing requirements, the exemptions requested will allow Duke Energy to better levelize distribution of the remaining examinations and tests across future outages and inspection periods within the 12-year ISI interval while still meeting the underlying purpose of the rule. Duke Energy will continue to meet the ASME Section XI requirements to distribute examinations among the three inspection periods. The added flexibility of Code Case N-921 allows Duke Energy to better align periodic examinations and tests with scheduled outages and maintenance work windows, while ensuring a continuous stream of examination data throughout the remainder of the extended ISI interval.

As demonstrated above, Duke Energy considers that this exemption request is in accordance with the criteria of 10 CFR 50.12. Specifically, the requested exemptions are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense and security. Additionally, special circumstances are present as previously described. Based on the nature of this exemption request, Duke Energy has concluded that granting these exemptions would not have an effect on the quality of human health or the environment.

VI.

Precedent

1. Dresden Nuclear Power Station, Units 2 and 3, Quad Cities Nuclear Power Station, Units 1 and 2, Request for Exemptions from 10 CFR 50.55a(a)(3)(ii), which incorporates by reference Regulatory Guide 1.147, Revision 21, for Code Case N-921, and 10 CFR 50.55a(y), dated February 14, 2025 (ADAMS Accession Number ML25045A177).

VII.

Reference

1. Final Rule, American Society of Mechanical Engineers Code Cases and Update Frequency, 89 Fed. Reg. 58039 (July 17, 2024).

2. Final Rule, American Society of Mechanical Engineers 2021-2022 Code Editions, 89 Fed. Reg. 70449 (Aug. 30, 2024).

3. Final Rule, Specific Exemptions; Clarification of Standards, 50 Fed. Reg. 50764 (Dec.

12, 1985).

4. U.S. NRC Regulatory Guide 1.147, Revision 21, Inservice Inspection Code Case Acceptability, ASME Code Section XI, Division 1, dated March 2024.

5. ASME Section XI, Division 1, Code Case N-921, Alternative 12-yr Inspection Interval Duration dated September 28, 2021.

6. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2017 Edition.

RA-24-0291 Enclosure Page 13

7. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2019 Edition.

8. American Society of Mechanical Engineers Code Case and Update Frequency, dated June 14, 2023 (ADAMS Accession No. ML23235A158).

9. NRC Responses to Public Comments, Final Rule: American Society of Mechanical Engineers Code Cases and Update Frequency, dated March 2024 ADAMS Accession No. ML23291A328).

10. McGuire, Unit 1 - Relief Request RA-19-0341, "Delay the Update to the ASME Code of Record for the First Inspection Period for MNS Unit 1', submitted January 23, 2020 (ADAMS Accession Number ML20023A272), approved August 21, 2020 (ADAMS Accession Number ML20230A205).

ATTACHMENT 1 H.B. Robinson Nuclear Plant, Unit 2 - Assessment of Previously Approved Alternatives

RA-24-0291 Page 1 of 2 H.B. Robinson Nuclear Plant, Unit 2 - 6th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-19-0106 (ISI) Reactor Pressure Vessel Upper Heads with Nozzles Having Pressure Retaining Partial-Penetration Welds 2

07/10/2019 (ML19191A139) 06/19/2020 (ML20097F088)

Up to and including the 34th (Fall 2024) RNP Unit 2 refueling outage.

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved only through the Fall 2024 refueling outage R2R34.

RA-22-0256 (ISI) Proposed Alternative for Steam Generator Welds 2

01/23/2023 (ML23023A093) 09/25/2023 (ML23256A088)

Defers the ISI examinations for the replacement steam generator welds, including the item number B2.40, C1.10, C1.20, C1.30, C2.21, and C2.22 components from RNP Unit 2 Sixth ISI Interval, but is only applicable to the end of the current licensed life of the plant (Unit 2 -

7/31/2030). Per the performance monitoring plan approved in letter RA-23-0136, Robinson does not require any performance monitoring (ADAMS Accession No. ML23201A140).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating license.

RA-24-0291 Page 2 of 2 H.B. Robinson Nuclear Plant, Unit 2 - 6th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-22-0257 (ISI) Proposed Alternative for Pressurizer Welds 2

02/17/2023 (ML23048A148) 10/19/2023 (ML23264A853)

Defers the ISI examinations for the pressurizer welds, including the item number B2.11 and B2.12 components from RNP Unit 2 Sixth ISI Interval, but is only applicable to the end of the current licensed life of the plant (Unit 2 - 7/31/2030).

Per the performance monitoring plan approved in letter RA 0154, Robinson does not require any performance monitoring (ADAMS Accession No. ML23201A141).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating license.

ATTACHMENT 2 McGuire Nuclear Station, Unit 1 - Assessment of Previously Approved Alternatives

RA-24-0291 Page 1 of 3 McGuire Nuclear Station, Unit 1-5th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-20-0031 (ISI) Delay to Update the Code of Record for Inservice Inspection 1

1/23/2020 (ML20023A272) 8/21/2020 (ML20230A205)

Alternative to delay updating the code of record until the second period of the fifth interval for MNS Unit 1. The duration of this relief is limited to the first period of the fifth interval.

Extending the current interval to 12 years does not impact the duration associated with this relief request, since the alternative is limited to Period 1 of the Fifth interval at MNS Unit 1.

RA-19-0352 (ISI) Alternative for Examination Category B-G-1, Item Number B6.20, Reactor Pressure Vessel Closure Stud, Volumetric and Surface Examinations 1

12/01/2020 (ML20336A033) 11/18/2022 (ML22096A003)

Alternative to extend the frequency of RPV closure stud volumetric and surface examination for the remainder of the currently licensed operating period for MNS Unit 1 (current license end date 6/12/2041).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating license.

RA-24-0291 Page 2 of 3 McGuire Nuclear Station, Unit 1-5th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-22-0256 (ISI) Proposed Alternative for Steam Generator Welds 1

01/23/2023 (ML23023A093) 09/25/2023 (ML23256A088)

Defers the ISI examinations for the replacement steam generator welds, including the item number B2.40, C1.20, C1.30, C2.21, and C2.22 components from MNS Unit 1 Fifth ISI Interval, but is only applicable to the end of the current licensed life of the plant (Unit 1 - 6/12/2041).

Performance monitoring plan approved in letter RA-23-0136 (ADAMS Accession No. ML23201A140).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating license.

RA-24-0291 Page 3 of 3 McGuire Nuclear Station, Unit 1-5th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-22-0257 (ISI) Proposed Alternative for Pressurizer Welds 1

02/17/2023 (ML23048A148) 10/19/2023 (ML23264A853)

Defers the ISI examinations for the pressurizer welds, including the item number B2.11, B2.12, and B3.110 components from MNS Unit 1 Fifth ISI Interval, but is only applicable to the end of the current licensed life of the plant (Unit 1 -

6/12/2041). Performance monitoring plan approved in letter RA-23-0154 (ADAMS Accession No. ML23201A141).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating license.

ATTACHMENT 3 Oconee Nuclear Station, Units 1, 2, and 3 - Assessment of Previously Approved Alternatives

RA-24-0291 Page 1 of 4 Oconee Nuclear Station, Units 1, 2, and 3-6th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval 15-ON-001 (ISI) Alternative to Defect Removal Prior to Repair/Replacement Activities on Low Pressure Service Water System Piping 1 & 2 06/12/2015 (ML15169A860) 12/29/2015 (ML15349A453)

Remains in effect for the remainder of the current renewed operating licenses of ONS Units 1 and 2, or until additional repairs are required on the subject LPSW piping.

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1 and 2.

RA-19-0418 (CISI) Alternative for Inservice Inspection of Containment Post-Tensioning System Components.

1, 2, & 3 05/06/2021 (ML21126A002) 12/07/2021 (ML21335A106)

Remains in effect for the remainder of the current renewed operating licenses of ONS Units 1, 2, and 3.

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1, 2, and 3. IWL request and not impacted by the proposed alternative.

RA-20-0328 (ISI) Alternative for Implementation of Extended Reactor Vessel Inservice Inspection Intervals for Oconee Units 1, 2, and 3 1, 2, & 3 01/19/2021 (ML21019A276) 11/19/2021 (ML21281A141)

Applies to 5th and 6th Intervals.

Extends Reactor Vessel B-A/B-D welds from 5th Interval to 6th Interval (i.e. 10 to 20 years).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative requires deferred 5th Interval reactor vessel exams for ONS Units 1, 2, 3 to be completed in the 6th Interval no later than 2032, 2033, and 2034, respectively.

RA-24-0291 Page 2 of 4 Oconee Nuclear Station, Units 1, 2, and 3-6th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-20-0036 (ISI) Request for Alternative to Defect Removal Prior to Performing Repair/Replacement Activities on Low Pressure Service Water (LPSW)

System Piping 1 & 2 3/2/2020 (ML20062G131) 7/30/2020 (ML20206K928)

This proposed alternative was approved for the remaining life of ONS Unit 1 and Unit 2.

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1 and 2.

RA-22-0174 (ISI) Request for Alternative in Accordance with 10CFR50.55a(z)(1) to Use ASME Code Case N-752, Risk-Informed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems,Section XI, Division 1 1, 2, & 3 07/27/2022 (ML22208A031) 12/13/2023 (ML23262A967)

Use is for the remainder of the current renewed operating licenses.

Applies to ASME Class 2 and 3 items or components except as listed in Section 1.0 of the request.

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1, 2, and 3.

RA-24-0291 Page 3 of 4 Oconee Nuclear Station, Units 1, 2, and 3-6th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-22-0256 (ISI) Proposed Alternative for Steam Generator Welds 1, 2, & 3 01/23/2023 (ML23023A093) 09/25/2023 (ML23256A088)

Defers the ISI examinations for the replacement steam generator welds, including the item number B2.40, C1.30, and C2.21 components, from the ONS Units 1, 2, and 3 Sixth ISI Interval but is only applicable to the end of the current licensed life of the plant (Unit 1 - 2/6/2033, Unit 2 -

10/6/2033, and Unit 3 - 7/19/2034).

Per the performance monitoring plan approved in letter RA-23-0136, Oconee does not require any performance monitoring (ADAMS Accession No. ML23201A140).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1, 2, and 3.

RA-22-0257 (ISI) Proposed Alternative for Pressurizer Welds 1, 2, & 3 02/17/2023 (ML23048A148) 10/19/2023 (ML23264A853)

Defers the ISI examinations for the pressurizer welds, including the item number B2.11, B2.12, and B3.110 components, from the ONS Units 1, 2, and 3 Sixth ISI Interval but is only applicable to the end of the current licensed life of the plant (Unit 1 -

2/6/2033, Unit 2 - 10/6/2033, and Unit 3 - 7/19/2034). Per the performance monitoring plan approved in letter RA-23-0154, Oconee does not require any performance monitoring (ADAMS Accession No.ML23201A141).

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1, 2, and 3.

RA-24-0291 Page 4 of 4 Oconee Nuclear Station, Units 1, 2, and 3-6th ISI Interval Assessment of Previously Approved Alternatives Relief Request Number Description Unit(s)

Affected Submittal Date (Reference)

Approval Date (Reference)

Duration of Approval Impact of 12-yr Interval on Technical Basis Supporting Previous Approval RA-23-0018 (ISI) Alternative to Utilize Modified ASME Code Case N-853 1, 2, & 3 05/04/2023 (ML23124A384) 10/20/2023 (ML23285A074)

Use of this alternative repair method and inspection criteria is limited to the 6th Interval.

Extending the current interval to 12 years does not impact the duration associated with this alternative request, since the alternative was approved for the remainder of the current renewed operating licenses of ONS Units 1, 2, and 3.