ML25231A222
| ML25231A222 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 09/04/2025 |
| From: | Wetzel B Plant Licensing Branch III |
| To: | Hafen S Northern States Power Company, Minnesota |
| References | |
| EPID L-2025 LLE-0013 | |
| Download: ML25231A222 (1) | |
Text
September 4, 2025 Mr. Shawn Hafen Site Vice President Northern States Power Company -
Minnesota Monticello Nuclear Generating Plant 2807 West County Road 75 Monticello, MN 55362
SUBJECT:
MONTICELLO NUCLEAR GENERATING PLANT, UNIT 1 - EXEMPTION FROM SPECIFIC REQUIREMENTS OF 10 CFR 50.55a IN SUPPORT OF ADOPTION OF CODE CASE N-921 (EPID L-2025-LLE-0013)
Dear Mr. Hafen:
The U.S. Nuclear Regulatory Commission has approved the enclosed exemption from specific requirements of Title 10 of the Code of Federal Regulations Section 50.55a, Codes and standards, to allow the implementation of the American Society of Mechanical Engineers Code Case N-921 after the start date of the sixth inservice inspection Program interval at Monticello Nuclear Generating Plant, Unit 1. This action is in response to your application dated April 4, 2025.
A copy of the exemption is enclosed.
Sincerely,
/RA/
Beth Wetzel, Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-263
Enclosure:
Exemption cc: Listserv
ENCLOSURE EXEMPTION FROM SPECIFIC REQUIREMENTS OF 10 CFR 50.55a NORTHERN STATES POWER COMPANY - MINNESOTA MONTICELLO NUCLEAR GENERATING PLANT, UNIT 1 DOCKET NO. 50-263
NUCLEAR REGULATORY COMMISSION Docket No. 50-263 Northern States Power Company, a Minnesota Corporation Monticello Nuclear Generating Plant, Unit 1 Exemption I. Background.
Northern States Power Company, a Minnesota Corporation (NSPC, the licensee) is the holder of the Subsequent Renewed Facility Operating License (SRFOLs) No. DPR-22, for the Monticello Nuclear Generating Plant, Unit 1 (MNGP), which consists of one boiling water reactor (BWR) nuclear power plant located in Monticello, Minnesota. The SRFOL provides, among other things, that the facilities are subject to all rules, regulations, and orders of the U.S. Nuclear Regulatory Commission (NRC, the Commission) now or hereafter in effect.
On July 17, 2024, the NRC issued a final rule incorporating by reference Regulatory Guide (RG) 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 21, in Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a, Codes and standards, paragraph(3)(ii) (89 FR 58039). This RG conditionally approved American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI (ASME BPV XI) Code Case N-921, Alternative 12-yr Inspection Interval Duration. This code case allows NRC licensees to implement an inservice inspection (ISI) program based upon a 12-year ISI interval, as opposed to the traditional 10-year ISI interval required by ASME BPV XI, Paragraph IWA-2431. RG 1.147 Revision 21 specifies four conditions on Code Case N-921.
Condition 1 states, 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. Condition 2 states, This code case can only be implemented at the beginning of an ISI interval as part of a routine update of the ISI program. The July 17, 2024, final rule also added 10 CFR 50.55a(y), which includes a definition
2 for the term inservice inspection interval. This definition specifies that the length of the ISI interval is defined in ASME BPV XI, Paragraph IWA-2431.
II. Request/Action.
By application dated April 4, 2025 (ML25097A091), the licensee, pursuant to 10 CFR 50.12, Specific exemptions, requested exemptions from certain requirements of 10 CFR 50.55a(a)(3)(ii) and 10 CFR 50.55a(y) to allow the use of Code Case N-921 after the start date of the sixth ISI interval at MNGP, which is not in accordance with Condition 2 on Code Case N-921, as specified in RG 1.147, Revision 21. The sixth ISI interval at MNGP began on June 21, 2023. The code of record for the MNGP sixth ISI interval is the 2019 Edition of the ASME Section XI, as incorporated by reference in 10 CFR 50.55a.
III. Discussion.
Pursuant to 10 CFR 50.12(a), the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR part 50 when (1) the 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 and (2) special circumstances are present. Under 10 CFR 50.12(a)(2), special circumstances are present when at least one of the following five conditions are met:
(i)
Application of the regulation in the particular circumstances conflicts with other rules or requirements of the Commission; or (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; or (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; or (iv) The exemption would result in benefit to the public health and safety that compensates
3 for any decrease in safety that may result from the grant of the exemption; or (v) The exemption would provide only temporary relief from the applicable regulation and the licensee or applicant has made good faith efforts to comply with the regulation; or (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.
A.
The Exemption is Authorized by Law The exemptions would authorize exemption from the requirements of 10 CFR 50.55a(a)(3)(ii) and 10 CFR 50.55a(y) to allow the use of Code Case N-921, after the start dates of the sixth ISI at MNGP. As stated, 10 CFR 50.12(a) allows the NRC to grant exemptions from the requirements of 10 CFR part 50, including 10 CFR 50.55a(a)(3)(ii) and 10 CFR 50.55a(y), when the exemptions are authorized by law. Exemptions are authorized by law where they are not expressly prohibited by statute or regulation. A proposed exemption is implicitly authorized by law if it will not present an undue risk to the public health and safety, is consistent with the common defense and security, and special circumstances are present, and no other provisions in law prohibit, or otherwise restrict, its application. The NRC staff has determined that no provisions in law expressly prohibit or otherwise restrict the application of the requested exemptions. The NRC staff has also determined, as explained below, that the requested exemptions will not present an undue risk to the public health and safety, are consistent with the common defense and security, and special circumstances are present.
Therefore, the NRC staff concludes that the exemption is authorized by law.
B.
The Exemption Presents no Undue Risk to Public Health and Safety The exemptions would allow the licensee to implement Code Case N-921 after the start dates of the sixth ISI interval at MNGP. The action does not change the manner in which the plant operates and maintains public health and safety because the exemptions do not result in a change to the facility or the current operating license. The licensee stated that extending the ISI interval by 2 years does not impact the technical basis supporting any of the currently
4 authorized 10 CFR 50.55a alternatives and does not create any particular challenge in reconciling the ISI inspection schedules to conform with the three four-year periods specified in Code Case N-921. The licensee also noted that this request does not pertain to the MNGP Containment Inspection Inservice Program (CISI). Accordingly, the NRC staff reviewed the alternatives listed in Section 3 of the licensees exemptions request for ISI interval-related risk impacts. The two pertinent alternatives are described below. The staff did not identify further pertinent alternatives.
Alternative Based on Plant Specific Analysis One authorized alternative (RR-002, ML24138A121) is based on a plant specific analysis approved through the request for alternative process of 10 CFR 50.55a(z)(1),
acceptable level of quality and safety. Specifically, Note (6) to ASME BPV Code,Section XI, Table IWB-2500-1, Examination Category B-D, allows the licensee to reduce the population of inspected RPV nozzle welds and inner radii to a minimum 25 percent population if the conditions of ASME BPV Code,Section XI, paragraph IWB-2500(f), subparagraphs (1) to (9),
are met. The licensee conducted plant-specific probabilistic fracture mechanics evaluations for specific nozzles to demonstrate that despite not meeting some of the conditions noted above, sampling inspection of these nozzles would support an acceptable level of quality and safety.
The NRC staff confirmed that extending the ISI interval from 10 to 12 years would not impact the conclusions for any of the subparagraph (1) to (9) evaluations documented in the NRC approval of the alternative. Therefore, the NRCs basis for approving this alternative is not impacted by extending the length of the ISI interval to 12 years.
5 Alternative Based on Topical Reports with 10-Year ISI Intervals One authorized alternative (RR-017, Monticello Nuclear Generation Plant (MNGP) -
Request For Relief No. 17 Regarding Examination Of Reactor Pressure Vessel Shell Circumferential Welds (TAC No. ME3526) Agencywide Documents Access and Management System Accession No. ML110200700) is based on approved topical reports which were originally generated assuming a 10-year ISI interval. This alternative is described below.
BWRVIP-05, BWR Vessel and Internals Project, BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations and NRC Safety Evaluation dated March 7, 2000 (ML003690281).
BWRVIP-74, BWR Vessel and Internals Project, BWR Reactor Pressure Vessel Inspection and Flaw Evaluation Guidelines and Demonstration of Compliance with the Technical Information Requirements of the License Renewal Rule (10 CFR 54.21) and NRC Safety Evaluation Report dated October 18, 2001 (ML012920549).
These topical reports (NRC safety evaluations ML003690281 and ML012920549, respectively) provide a basis for bounding circumferential welds in the reactor vessel through inspection of axial welds consistent with Generic Letter 98-05, Boiling Water Reactor Licensees Use of the BWRVIP-05 Report to Request Relief from Augmented Examination Requirements on Reactor Pressure Vessel Circumferential Shell Welds. Under this generic letter, licensees must demonstrate that (1) at the expiration of their license, the circumferential welds will continue to satisfy the limiting conditional failure probability for circumferential welds in the staffs July 28, 1998, safety evaluation, and (2) licensees have implemented operator training and established procedures that limit the frequency of cold over-pressure events to the amount specified in the staffs July 28, 1998, safety evaluation. Neither of these criteria are related to the length of the ISI interval. Therefore, the NRC staff finds that the NRCs bases for approving these alternatives are not impacted by extending the length of the ISI interval to 12 years. For this exemption request, the above discussion pertains to RR-017.
6 C.
The Exemption is Consistent with the Common Defense and Security The requested exemptions would allow the licensee to implement Code Case N-921 after the start dates of the sixth ISI interval at MNGP. The change is administrative in nature, adequately controlled by the ISI Program criteria and ASME Code requirements and is not related to security issues. The length of the ISI interval is not related to security issues. Because the common defense and security is not impacted by the exemptions, the exemptions are consistent with the common defense and security.
D.
Special Circumstances The regulation under 10 CFR 50.12(a)(2) states, in part, that [t]he Commission will not consider granting an exemption unless special circumstances are present, and describes, in 10 CFR 50.12(a)((i) - (vi), the conditions under which special circumstances exist. In Section III(d) of the licensees exemptions request, the licensee stated that three of the six special circumstances listed in 10 CFR 50.12(a)(2) are present:
(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.
(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.
(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.
The NRC staff performed an independent review of the special circumstances claimed by the licensee.
For the special circumstances in 10 CFR 50.12(a)(2)(ii), the licensee stated that the purpose of the July 2024 final rule (89 FR 58039) was to identify ASME code cases that the NRC determined to be acceptable for use. The licensee noted that NRCs approval of Code
7 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. The licensee provided the following support to the claim that application of the regulation would not serve the underlying purpose of the rule:
Table 2 of the licensees submittal described the new inspection period dates and corresponding refueling outages.
The licensee evaluated all NRC-authorized alternative requests in Section 3 of the licensees submittal, consistent with NRC concerns expressed in the 89 FR 58039 final rule preamble (see NRC staffs independent review in Section III.B above).
The licensee stated that modifying the site ISI program occurs regularly mid-interval and does not present any particular challenge. The licensee described example operational considerations for revising the ISI examination schedule mid-interval including factors such as dose, availability of examination equipment and personnel, availability of personnel for required support tasks (e.g. insulation, scaffold, weld preparation), outage schedules, outage duration, and changes in operating strategy.
The licensee noted that it had already established the first and second periods of the current ISI program interval anticipating Code Case N-921 authorization.
In the 89 FR 58039 final rule preamble, the NRC communicated that order and predictability of licensee ISI programs is a paramount consideration. The careful advance planning required by ASME BPV XI and 10 CFR 50.55a maximizes licensee effectiveness in successfully executing all ISI requirements. The successful execution of ISI requirements, in turn, contributes to nuclear safety by providing a data stream used to continuously evaluate the structural integrity of safety-related components. The NRC staff determined that the licensee provided adequate evidence that, if the NRC approves the proposed exemption, the ISI program at MNGP will be managed in a manner that promotes order and predictability.
8 In the 89 FR 58039 final rule, the NRC added a new condition requiring that Code Case N-921 be implemented at the start of a new ISI interval. The basis for the condition is that implementation of Code Case N-921 in the middle of an ISI interval creates complications related to existing examination schedules and alternatives that were approved assuming a 10-year ISI interval. As discussed above, the licensee demonstrated that no currently approved alternatives are impacted by extending the length of the ISI interval to 12 years.
Another concern identified by the NRC staff with allowing mid-cycle implementation of Code Case N-921 involves potential complications of reconciling ISI inspection schedules to conform with the three 4-year periods specified in Code Case N-921. As discussed above, the licensee stated that, in anticipated implementation of Code Case N-921, it proactively adjusted examination schedules to maintain compliance with Code Case N-921 periodic distribution requirements. Therefore, the NRC staff concludes that application of the regulation would not serve the underlying purpose of the rule because the licensee demonstrated that mid-cycle implementation of Code Case N-921 will have no impact on the ISI program at MNGP. Based on the above, the NRC staff determined that the special circumstances described in 10 CFR 50.12(a)(2)(ii) are present for the requested exemptions. Since the regulations require that one of the special circumstances in 10 CFR 50.12(a)(2) be satisfied to support an exemption, the NRC staff did not evaluate the licensees additional claims that the special circumstances in 10 CFR 50.12(a)(2)(iii) and (vi) are also applicable.
E.
Environmental Considerations The NRC staff determined that the exemption discussed herein meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(25) because (i) there is no significant hazards consideration; (ii) there is no significant change 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
9 consequences from radiological accidents; and (vi) the requirements from which an exemption is sought are among those identified in 10 CFR 51.22(c)(25)(vi), including requirements of an administrative, managerial, or organizational nature. Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need to be prepared in connection with the issuance of the exemption. The basis for this NRC staff determination is discussed as follows with an evaluation against each of the requirements in 10 CFR 51.22(c)(25).
Requirements in 10 CFR 51.22(c)(25)(i) - There is no significant hazards consideration.
The criteria for determining whether an action involves a significant hazards consideration are found in 10 CFR 50.92(c). The exemptions only involve an ISI program implementation change, which is administrative in nature. The exemptions do not adversely affect plant equipment, operation, or procedures. Therefore, there are no significant hazard considerations, because granting the exemptions would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
Requirements in 10 CFR 51.22(c)(25)(ii) - There is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite.
The exemptions involve only an ISI program implementation change, which is administrative in nature, and does not involve any changes in the types or significant increase in the amounts of any effluents that may be released offsite.
Requirements in 10 CFR 51.22(c)(25)(iii) - There is no significant increase in individual or cumulative public or occupational radiation exposure.
Since the exemptions involve only an ISI program implementation change, which is administrative in nature, it does not contribute to any significant increase in occupational or public radiation exposure.
10 Requirements in 10 CFR 51.22(c)(25)(iv) - There is no significant construction impact.
Since the exemptions involve only an ISI program implementation change, which is administrative in nature, it does not involve any construction impact.
Requirements in 10 CFR 51.22(c)(25)(v) - There is no significant increase in the potential for or consequences from radiological accidents.
The exemptions involve only an ISI program implementation change, which is administrative in nature and does not impact the potential for or consequences from accidents.
Requirements in 10 CFR 51.22(c)(25)(vi)(I) - The requirements from which the exemption is sought involve requirements that are administrative in nature.
The exemptions involve only an ISI program implementation change regarding examination scheduling requirements and other requirements of an administrative, managerial, or organizational nature, because they are associated with the marginal extension from a 10-year to 12-year ISI interval.
Based on the above, NRC determined that the exemptions meet the eligibility criteria for the categorical exclusion set forth in 10 CFR 51.22(c)(25). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with these exemption requests.
IV. Conclusions.
Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12, the exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security. Also, special circumstances are present. Therefore, the Commission hereby grants NSPCs request for exemptions from
11 10 CFR 50.55a(a)(3)(ii) and 10 CFR 50.55a(y) to allow the implementation of ASME Code Case N-921 after the start dates of the sixth ISI interval at MNGP (not to the CISI program).
These exemptions are effective upon issuance.
Dated: September 4, 2025.
For the Nuclear Regulatory Commission.
Jamie Pelton, Acting Director, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation JAMIE PELTON Digitally signed by JAMIE PELTON Date: 2025.09.04 09:34:44 -04'00'
- via eConcurrence NRR-048 OFFICE NRR/DORL/LPL3/PM*
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NAME BWetzel SLent ABuford SBailey DATE 8/19/2025 8/20/2025 8/21/2025 8/21/2025 OFFICE NRR/DORL/LPL3/BC (A)*
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NAME IBerrios JPelton BWetzel DATE 8/29/2025 9/4/2025 9/4/2025