ML24328A001
| ML24328A001 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 11/25/2024 |
| From: | Nuclear Energy Institute |
| To: | Licensing Processes Branch |
| References | |
| Download: ML24328A001 (9) | |
Text
[DATE]
U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
[Applicable Sites and NRC Docket Nos.]
SUBJECT:
Exemption Request Associated with Implementation of Code Case N-921 In accordance with 10 CFR 50.12, "Specific exemptions," paragraph (a)(2), [Licensee] is requesting an exemption to allow implementation of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Code Case N-921 Alternative 12-yr Inspection Interval Duration. Specifically, this exemption request concerns implementation of Condition (2) associated with Code Case N-921. Code Case N-921 is listed in in Table 2 of NRC Regulatory Guide 1.147, Revision 21 which is incorporated by reference in 10 CFR 50.55a(a)(3)(ii).
[Licensee] requests approval of the proposed exemption by [DATE].
There are no regulatory commitments contained in this letter.
If you have any questions or require additional information, please contact [NAME] at [Phone Number].
Respectfully,
[Signature Block]
Enclosure
[Applicable Utility and Sites]
Exemption Request [Applicable Number]
Exemption Request in Accordance with 10 CFR 50.12 Exemption Request Associated with Implementation of ASME Code Case N-921
Exemption Request [Number]
Page 1 of XX 1.0 ASME CODE COMPONENT(S) AFFECTED:
All ASME Code Class 1, 2, 3, and MC components.
This exemption concerns implementation of Condition (2) associated with Code Case N-921, Alternate 12-yr Inspection Interval Duration.
2.0 APPLICABLE CODE EDITION AND ADDENDA:
The applicable Edition of the ASME Code,Section XI is identified in Table 1.
Table 1 Plant/Unit(s)
Interval1 ASME Section XI Code Edition Current Interval Start Date Current Interval End Date Proposed 12-yr Interval End Date2 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.
3.0 APPLICABLE REGULATORY REQUIREMENT:
10 CFR 50.55a(y) defines the inservice inspection (ISI) interval as, 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.
10 CFR 50.55a(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.
NRC Regulatory Guide 1.147, Revision 21, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, approved the use of ASME Code Case N-921 with 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).
(4) The exceptions of IWB-2411(a), IWC-2411(a), and IWD-2411(a) also apply to Table 1 of this code case.
4.0 REASON FOR EXEMPTION REQUEST:
Regulatory Guide 1.147, Revision 21, Table 2 conditioned the use of Code Case N-921, specifically limiting implementation to the beginning of the inservice inspection (ISI) interval. For this reason, [Licensee] is requesting an exemption for the plants listed in Table 1, in accordance with 10 CFR 50.12(a)(2)(ii), from Condition 2 on Code Case N-921. Exemption from Condition 2 is required because these plants did not apply the Case at the beginning of the current ISI interval as part of the routine update of the ISI program. This Code Case establishes a 12-year ISI interval for inservice inspection programs. The marginal extension from
Exemption Request [Number]
Page 2 of XX 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. Implementation of Code Case N-921 will allow these plants to gain the benefits of the Case while still meeting the underlying purpose of the rule.
During the most recent ISI interval update for each of the units listed in Table 1, [Licensee] proactively acted, based on the information publicly available, in anticipated implementation of Code Case N-921 in the new interval. This includes revision of the period start and end dates to accommodate outage schedules and adjusting examination schedules accordingly while maintaining compliance with periodic distribution requirements. For this reason, exemption is requested from Condition 2, thus allowing the plants listed in Table 1 to implement Code Case N-921. All other conditions associated with Code Case N-921 as specified in Regulatory Guide 1.147, Revision 21, Table 2 remain applicable.
5.0 EXEMPTION REQUEST AND BASIS FOR USE:
5.1 Exemption Request:
In accordance with 10 CFR 50.12(a)(2)(ii), [Licensee] requests an exemption from Condition (2) of Code Case N-921 cited in Section 3.0 of this request. In lieu of Condition (2), the following requirements will be met.
5.1.1 [Licensee] proposes to implement Code Case N-921 for the remainder of the current ISI interval for the plants listed in Table 1.
5.1.2 All other conditions associated with Code Case N-921 as specified in Regulatory Guide 1.147, Revision 21, Table 2 apply.
5.1.3 The impact of the extended interval on the continued use of previously approved relief requests applicable to the current ISI interval is provided in Attachments 1 - X.
Implementation of Code Case N-921 following the start of the current ISI interval does not inhibit the ability of [Licensee] 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 inspection interval. This will ensure that each inspection period during the 12-year interval will have at least two refueling outages. During the most recent ISI interval update for each of the plants listed in Table 1,
[Licensee] established the periods as a 4-4-2 year breakdown so the additional 2 years allowed by N-921 could be added to the third period. The specific period dates and proposed interval dates, with outages, are shown for each Unit in Tables 2 - xxx below.
Table 2: Station XXX Unit XXX - XXX ISI Interval, XXX CISI Interval
Exemption Request [Number]
Page 3 of XX Interval Periods Outages Start Date to End Date Start Date to End Date Outage Numbers 6th ISI Interval 4th CISI Interval Beginning to End (current)
End (proposed)*
1st Beginning to End Outage #
Date Outage #
Date 2nd Beginning to End Outage #
Date Outage #
Date 3rd Beginning to End (current)
End (proposed)*
Outage #
Date Outage #**
Date Notes:
- Proposed ISI interval end date for implementation of a 12-yr interval via N-921.
- Proposed last outage for implementation of a 12-yr interval via N-921.
5.2 Basis for the Exemption Request is as Follows:
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).
Exemption Request [Number]
Page 4 of XX The first part of the comment is based on the perceived extra burden to the industry and the NRC to implement Code Case N-921 in the middle of an ISI interval. Owners of nuclear power plants regularly revise the ISI examination schedule mid-interval. Reasons for revising the ISI examination schedule mid-interval 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, etc. Maintaining the ISI examination schedule, including mid-interval changes, is core business for ISI program owners and implementation of Code Case N-921 mid-interval does not result in a significant burden to Owners. As previously mentioned, during the most recent ISI interval updated, [Licensee] took specific actions in anticipation of implementation of Code Case N-921 in the new interval. This includes revision of the period start and end dates and adjusting examination schedules accordingly.
The second part of the comment is based upon the potential need to resubmit previously approved alternatives that were based on a 10-year ISI interval. [Licensee] performed a review of all previously authorized alternatives (relief requests) for the plants listed in Table 1 and assessed the impact of extending the interval by 2 years to implement Code Case N-921. The results of this assessment determined that.[summarize results]. The full assessment of each previously approved alternative and required actions (if applicable) are included in Attachments 1-X of this exemption request.
For the reasons stated above, Condition 2 on N-921 is not required to satisfy the underlying purpose of the rule which is to provide requirements for the use of certain codes and standards for design, construction, and inservice inspection of nuclear power plants to provide reasonable assurance of adequate protection of public health and safety, to promote the common defense and security, and to protect the environment.
5.3 Conclusion Based on current ISI examination and testing requirements, the exemption requested will allow [Licensee] 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. This added flexibility allows plants 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.
Exemption Request [Number]
Page 5 of XX 6.0 DURATION OF PROPOSED EXEMPTION:
Exemption is requested for the remainder of each plants extended ISI interval as specified in Section 2.0, Table 1.
7.0 PRECEDENTS
None.
8.0 REFERENCES
8.1 Federal Register (Vol. 89, No. 137, July 17, 2024) - Approval of American Society of Mechanical Engineers Code Cases.
8.2 Federal Register (Vol. 89, No. 169, August 30, 2024) - Approval of American Society of Mechanical Engineers 2021-2022 Code Editions.
8.3 U.S. NRC Regulatory Guide 1.147, Revision 21, Inservice Inspection Code Case Acceptability, ASME Code Section XI, Division 1, dated March 2024.
8.4 ASME Section XI, Division 1, Code Case N-921, Alternative 12-yr Inspection Interval Duration dated September 28, 2021.
8.5 America Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2017 Edition.
8.6 America Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2019 Edition.
8.7 ML23235A158, Comment (013) from Anonymous on PR American Society of Mechanical Engineers Code Case and Update Frequency, dated June 14, 2023.
8.8 ML23291A328, Final Rule: NRC Responses to Public Comments, Final Rule: American Society of Mechanical Engineers Code Cases and Update Frequency, dated March 1, 2024.
Exemption Request [Number]
ATTACHMENT 1 Site Specific Relief Request Applicability Evaluation
Exemption Request [Number]
Page 1 of XX STATION XXX UNIT XXX - XXX ISI Interval and XXX CISI Interval Relief Requests Relief Request Number Description Unit(s)
Affected Submittal Date (Reference)
Approval Date (Reference)
Duration of Request Evaluation of Applicability for 12-yr Interval