L-MT-24-001, 10 CFR 50.55a Request RR-017 - Inservice Inspection (ISI) Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) During the Fifth Ten-Year Interval

10 CFR 50.55a Request RR-017 - Inservice Inspection (ISI) Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) During the Fifth Ten-Year Interval

ML24033A295
Person / Time
Site:	Monticello
Issue date:	01/30/2024
From:	Brown G Northern States Power Company, Minnesota, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-24-001
Download: ML24033A295 (1)

Text

fl Xcel Energys 2807 West County Road 75 Monticello, MN 55362

January 30, 2024 L-MT-24-001 10 CFR 50.55a(g)(5)(iii)

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22

10 CFR 50.55a Request RR-017: lnservice Inspection {ISi) Impracticality in Accordance with 10 CFR 50.55a{g){5){iii} during the Fifth Ten-Year Interval

Pursuant to 10 CFR 50.55a(g)(5)(iii), Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, requests relief from certain examination coverage requirements imposed by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," for the Monticello Nuclear Generating Plant (MNGP).

This 10 CFR 50.55a request is for nozzle-to-vessel weld examinations performed during the 2019, 2021, and 2023 refueling outages where the required coverage of "essentially 100 percent" could not be obtained when examined to the extent practical. The basis for the 10 CFR 50.55a request is that compliance with the specified requirements is impractical due to plant design.

NSPM is submitting this request for the Fifth Ten-Year ISi Interval and requests approval by March 2, 2025.

If there are any questions or if additional information is needed, please contact Ron Jacobson at (612) 330-6542 or ronald.g.jacobson@xcelenergy.com.

Summary of Commitments

This letter makes no new commitments and no revisions to existing commitments.

_/.. Lr-;:.*~)./e: ~-. 7 ~o. ~;::x-*---.

Gregory D. Brown C.--

Plant Manager, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota Document Control Desk L-MT-24-001 Page 2

Enclosure with Attachments 1-3

cc: Administrator, Region III, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC L-MT-24-001 NSPM Enclosure

10 CFR 50.55a Request RR-017

Inservice Inspection (ISI) Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) during the Fifth Ten-Year Interval

Pursuant to 10 CFR 50.55a(g)(5)(iii), Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, requests relief from certain examination coverage requirements imposed by the American Society of Mechanical Engineers (ASME)

Boiler and Pressure Vessel (BPV) Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, for the Monticello Nuclear Generating Plant (MNGP).

1.0 ASME CODE COMPONENTS AFFECTED

The components affected are ASME BPV Code, Section Xl, Class 1, Reactor Pressure Vessel (RPV), nozzle-to-vessel (NV) shell welds specified below and are discussed further in-detail in Tables A, B, and C. This request is based upon examinations performed during the 2019, 2021, and 2023 MNGP refueling outages, which occurred in the Second and Third Periods of the Fifth Ten-Year ISI Interval.

2019 Limited Exams (2nd Period)

Main Steam Nozzle N-3C: Weld N-3C NV Feedwater Inlet Nozzle N-4B: Weld N-4B NV Standby Liquid Control Nozzle N-10: Weld N-10 NV

2021 Limited Exams (3rd Period)

Recirculation Inlet Nozzle N-2G: Weld N-2G NV Rx Head, Spare Nozzle N-6A: Weld N-6A NV Rx Head, Vent Nozzle N-7: Weld N-7 NV

2023 Limited Exams (3rd Period)

Feedwater Inlet Nozzle N-4D: Weld N-4D NV

2.0 APPLICABLE CODE EDITION AND ADDENDA

The applicable ASME Section Xl Code for the MNGP Fifth Ten-Year ISI Interval is the 2007 Edition with the 2008 Addenda. ASME Section XI, Appendix VIII requirements are implemented as required by 10 CFR 50.55a. Ultrasonic procedures and personnel are qualified to the Performance Demonstration Initiative (PDI). The PDI Program satisfies the requirements of the 2007 Edition with 2008 Addenda of Section XI, Appendix VIII, as modified by 10 CFR 50.55a.

Page 1 of 8 L-MT-24-001 NSPM Enclosure 3.0 APPLICABLE CODE REQUIREMENT

ASME Class 1 NV shell welds are subject to the examination requirements of Subsection IWB-2500, Table IWB-2500-1 as shown below, and are required to be examined once within the Fifth Ten-Year ISI Interval:

Code Class: 1

References:

IWA-2200(c)

IWB-2500, Table IWB-2500-1 Examination Category: B-D, Full Penetration Welded Nozzles in Vessels Item Number: B3.90

Description:

NV Shell Welds Component Numbers: See Section 1.0 above and Attachment 1, Tables A, B, and C System: Reactor Vessel Examination Method: Volumetric - Ultrasonic Testing (UT)

Examination Volume: Figure IWB-2500-7(b)

At the start of the MNGP ISI 5th Interval, ASME Code Case N-613-1 was applied in the ISI Plan per issued Regulatory Guide (RG) 1.147 Revision 16, "Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1" (Reference 1). RG 1.147, Revision 16, Table 1 lists ASME Code Case N-613-1 (Reference 2) as acceptable to the NRC for use by a licensee with no identified limitations or modifications.

In March 2017, the NRC issued RG 1.147, Revision 18 (Reference 3), in which they identify in Table 1, ASME Code Case N-613-2 (Reference 4) as acceptable to the NRC for use by a licensee with no identified limitations or modifications. However, for the MNGP ISI 5th Interval, Second and Third Periods, NSPM continued using N-613-1 as allowed by RG 1.147. Similarly, the NRC issued RG 1.147 Revision 19 (Reference 13) in October 2019 (prior to the 2021 outage) and RG 1.147 Revision 20 (Reference 14) in December 2021 (prior to the 2023 outage). Both of these latter two revisions continued to authorize ASME Code Case N-613-2 as acceptable for use with the same allowance for the use of the earlier N-613-1 Code Case while completing the current ISI ten-year interval.

As an acceptable alternative to ASME Section XI Figure IWB-2500-7(b) for RPV NV welds, ASME Code Case N-613-1 permits an examination volume that includes the width of the reactor-nozzle-to-shell weld plus one-half inch of adjacent base metal on each side of the widest part of the weld. In comparison, the examination volume required by the Figure IWB 2500-7(b) includes the width of the weld plus the adjacent base metal on each side of the widest part of the weld equal to one-half of the vessel shell wall thickness.

ASME Section XI IWA-2200(c) states in part:

When performing VT-1, surface, radiographic, or ultrasonic examination on a component with defined surface or volume, essentially 100% of the required

Page 2 of 8 L-MT-24-001 NSPM Enclosure surface or volume shall be examined. Essentially 100% coverage is achieved when the applicable examination coverage is greater than 90%...

Per IWA-2200(c), Nonmandatory Appendix S [Evaluating Coverage for Section XI Nondestructive Examination] may be used as a guideline to determine examination coverage, i.e., when the defined volume cannot be obtained due to a volumetric limitation.

Nonmandatory Appendix S, Article S-3000, specifically Sub-Article S-3500, provides examination coverage evaluation guidelines for ultrasonic examination of welds.

Nonmandatory Appendix S defines a volumetric limitation as:

Inability to examine the required volume because of interference, obstruction, geometrical configuration, or metallurgical condition of material being examined.

4.0 IMPRACTICALITY OF COMPLIANCE

Construction Permit (CP) CPPR-31 was obtained for the MNGP on June 19, 1967. The MNGP systems and components were designed for construction before the examination requirements of ASME Section Xl were formalized and published. Therefore, because MNGP was not specifically designed to meet the requirements of ASME Section Xl, full compliance is not feasible or practical within the limits of the current plant design.

10 CFR 50.55a recognizes the limitations to inservice inspection of components in accordance with Section XI of the ASME Code, which are imposed due to early plants design and construction, as follows:

10 CFR 50.55a(g)(1): Inservice inspection requirements for older plants (pre 1971 CPs). For a boiling or pressurized water-cooled nuclear power facility whose construction permit was issued before January 1, 1971, components (including supports) must meet the requirements of paragraphs (g)(4) and (g)(5) of this section to the extent practical.

10 CFR 50.55a(g)(4): Inservice inspection standards requirement for operating plants. Throughout the service life of a boiling or pressurized water-cooled nuclear power facility, components (including supports) that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements, except design and access provisions and preservice examination requirements, set forth in Section XI of editions and addenda of the ASME BPV Codeto the extent practical within the limitations of design, geometry, and materials of construction of the components.

10 CFR 50.55a(g)(5)(iii): ISI program update: Notification of impractical ISI Code requirements. If the licensee has determined that conformance with a Code requirement is impractical for its facility the licensee must notify the NRC and submit, as specified in § 50.4, information to support the determinations.

Page 3 of 8 L-MT-24-001 NSPM Enclosure The examination limitations on the subject components are due to inherent nozzle design geometric contours (see Attachment 1 Tables A, B, and C; and Attachment 2).

A description of the examination methodology used to provide the maximum obtainable coverage is provided in Section 6 of this request. This methodology is based on ASME Section XI, Appendix VIII qualification and was applied to the extent practical within the design constraints of the components. Attachment 2 provides cross-sectional diagrams of the subject welds showing the geometric contour of the component design in relation to the welds and the coverage obtained within the examination volume requirements of ASME Code Case N-613-1, Figure 2.

5.0 BURDEN CAUSED BY COMPLIANCE

Compliance with the examination coverage requirements of ASME Section XI would require modification, redesign, or replacement of components where geometric contour and physical obstruction is inherent to the component design and installation.

6.0 PROPOSED ALTERNATIVE AND BASIS FOR USE

6.1 Proposed Alternative

NSPM requests relief for the components listed in Attachment 1 Tables A, B, and C on the basis that the required examination coverage of "essentially 100 percent" is impractical due to physical obstructions and the limitations imposed by design, geometry, and materials of construction.

NSPM has performed qualified examinations that achieved the maximum, practical amount of coverage obtainable within the limitations imposed by the design of the components with no detectable indications.

Therefore, pursuant to 10 CFR 50.55a(g)(5)(iii), NSPM requests authorization of an alternative to the requirements of ASME Section XI Table IWB-2500-1, Category B-D, Item B3.90 and associated ASME Code Case N-613-1 and proposes to use these completed exams as an acceptable alternative that provides reasonable assurance of continued structural integrity.

6.2 Basis for Use

6.2.1 Nozzle-to-Vessel Shell Welds

2019 2021 2023 N-3C NV N-2G NV N-4D NV N-4B NV N-6A NV N-10 NV N-7 NV

The NSPM Nondestructive Examination (NDE) UT procedures incorporate inspection techniques qualified under Appendix VIII of the ASME Section XI Code by the PDI.

Page 4 of 8 L-MT-24-001 NSPM Enclosure

Examinations of the RPV nozzle-to-shell welds were performed from the RPV exterior surface using a manual contact method from the nozzle blend radius, the NV shell weld, and vessel shell surface. Coverage using the alternative examination volume permitted by Code Case N-613-1 was obtained by following the scan parameters designated within NSPM NDE procedures for each nozzle configuration and angle, including those parameters defined by MNGP-specific Electric Power Research Institute (EPRI) computer modeling reports (References 5 and 6). Note that the scans defined by the EPRI reports are applicable only to the inner 15 percent of the weld volume and only when scanning in a circumferential direction, parallel to the weld.

The refracted longitudinal wave mode of propagation was applied for all scans of the exam volume in the radial direction, perpendicular to the weld. The refracted longitudinal wave mode of propagation was also applied to the outer 85 percent of the exam volume for parallel scans.

As required by the NSPM NDE procedures and the EPRI computer modeling reports, the shear wave mode of propagation was applied for each of the transducer and wedge combinations required for the remaining inner 15 percent of the parallel scan exam volume.

The subject nozzle-to-vessel welds received the required examination(s) to the extent practical within the limited access of the component design. One hundred percent coverage was obtained for the inner 15 percent of the examination volume for the radial and parallel scans.

The examination limitations for the subject components were encountered within the outer 85 percent of the examination volume for the parallel and radial scans. For the examinations conducted, satisfactory results were achieved, and no flaw indications were detected.

Due to the design of these nozzle-to-shell welds, it was not feasible to effectively perform a volumetric examination of "essentially 100 percent" of the required volume. The NV welds are accessible from the vessel plate side of the weld and are examined to the extent practical with qualified techniques; however, the curvature of the nozzle forging and proximity to the weld preclude obtaining further coverage of the excluded areas within the outer 85 percent of the examination volume.

6.2.2 Exam Coverage Determination

As required by procedure, when limitations to ISI examinations are encountered that prevent obtaining full coverage of a required volume, the limitations are required to be quantified and recorded.

The method used to determine coverage is based on field measurements applied to a two dimensional plot. This allows an informed approximation to be made of the coverage achieved.

The methodology is appropriate to the application in that the limitations are physical, and the methods applied to the examination are established by qualified techniques.

The coverage drawings in Attachment 2 give a representation of the examination volume and the weld interface line shown in Figure 2 of Code Case N-613-1 for the NV welds. The areas of examination volume coverage and areas of no examination volume coverage are identified on

Page 5 of 8 L-MT-24-001 NSPM Enclosure the respective drawing for each nozzle. The contour on the exterior surface of the nozzles causes transducer liftoff and inhibits the ability to maintain adequate coupling necessary to transmit and receive the ultrasonic sound energy.

Additional coverage with meaningful results was not achievable or practical for the limited areas with implementation of performance-based examination methods without redesigning and modifying the components to allow additional scanning surfaces. NSPM has concluded that if significant service-induced degradation existed in the subject welds, it would have been identified by the examinations performed. Therefore, in accordance with 10 CFR 50.55a(g)(1) and (4), each of the subject welds were examined to the extent practical.

For comparison with current results, Table D of Attachment 3 to this Enclosure provides historical examination results from the Fourth Ten-Year ISI Interval for the subject welds, including percent coverage and their corresponding, granted 10 CFR 50.55a requests (References 8, 9 and 10). The coverage obtained for the Fourth Interval exams was the same as obtained for the current exams listed in Attachment 1, Tables A, B and C.

6.2.3 Materials, Aging Management, Similar Components

The materials for the subject components are A508 Class 2 nozzle forgings welded to A533 Grade B, Class 1 vessel shell plate. The weld filler material for the subject joints was E8018NM. Internal surface cladding materials are E309 15 for the base layer and ER308L or E308L 15 for subsequent layers.

The MNGP reactor vessel water chemistry is controlled in accordance with Revision 1 of the BWR Water Chemistry Guidelines (Reference 7). Hydrogen water chemistry system is used to reduce the oxidizing environment in the reactor coolant. Beginning in 2013, NSPM has also implemented Online Noble-Metal Chemistry at MNGP. These additional measures provide added assurance against the initiation of cracking or corrosion from the inside surface of the reactor vessel. An inerted primary containment environment during operation provides assurance of corrosion protection on the outside surface of the reactor vessel.

Additionally, as Class 1 Examination Category B-P components, system pressure testing with VT-2 visual examinations are required every outage prior to startup. The VT-2 examinations were performed on the subject components in association with the Reactor Coolant Pressure Boundary system pressure tests performed during the 2019, 2021, and 2023 refueling outages. No evidence of pressure boundary leakage was identified during these system tests.

As shown in Table E of Attachment 3, eight NV welds with limitations to coverage were examined during previous outages in the current Interval and relief was granted by the NRC (References 11 and 12) pursuant to 10 CFR 50.55a(g)(6)(i).

6.2.4 Summary

The provisions described above, as an alternative to the Code requirement for examination coverage, will continue to provide reasonable assurance of the structural integrity of the

Page 6 of 8 L-MT-24-001 NSPM Enclosure subject welds. The volumetric examinations were completed to the extent practical, and no unacceptable flaws were identified. VT-2 examinations performed on the subject components during system pressure testing each refueling outage in accordance with examination Category B-P provide continued assurance that the structural integrity of the subject components is maintained. Additionally, the MNGP Water Chemistry Program and inerted primary containment environment provide added measures of protection for the component materials.

Eight NV weld examinations, as shown in Table E of Attachment 3, were previously performed during the Fifth Ten-Year ISI Interval having limitations with respect to coverage, and relief was granted by the NRC pursuant to 10 CFR 50.55a(g)(6)(i). Similarly, relief was granted in the Fourth Ten-Year Interval, as shown in Table D of Attachment 3, for the components included in this request.

Therefore, pursuant to 10 CFR 50.55a(g)(5)(iii), NSPM requests that the NRC grant relief from the ASME Section XI examination requirements for the subject NV welds.

7.0 DURATION OF PROPOSED ALTERNATIVE

NSPM requests the granting of this relief for the MNGP Fifth Ten-Year Inservice Inspection Interval Program that began on September 1, 2012 and ended on May 31, 2023.

8.0 PRECEDENTS

The NRC has previously granted similar relief for the MNGP for the Fifth Ten-Year Inservice Inspection Interval (References 11 and 12). The NRC also granted similar relief for these components during the Fourth Ten-Year Inservice Inspection Interval (References 8, 9, and 10).

9.0 REFERENCES

1. NRC Regulatory Guide 1.147, Revision 16, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," dated October 2010 (ADAMS Accession No. ML101800536).

2. ASME Section XI Code Case N-613-1, Ultrasonic Examination of Full Penetration Nozzles in Vessels, Examination Category B-D, Item Nos. B3.10 and B3.90, Reactor Nozzle-To-Vessel Welds, Figs. IWB-2500-7(a), (b), and (c),Section XI, Division 1," dated August 20, 2002.

3. NRC Regulatory Guide 1.147, Revision 18, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," dated March 2017 (ADAMS Accession No. ML16321A336).

4. ASME Section XI Code Case N-613-2, Ultrasonic Examination of Full Penetration Nozzles in Vessels, Examination Category B-D, Item Nos. B3.10 and B3.90, Reactor

Page 7 of 8 L-MT-24-001 NSPM Enclosure Nozzle-To-Vessel Welds, Figs. IWB-2500-7(a), (b), and (c),Section XI, Division 1," dated December 20, 2010.

5. EPRI Internal Report IR-2004-63, Monticello Nozzle Inner Radius and Nozzle-to-Shell Weld Examinations, dated December 2004.

6. EPRI Internal Report IR-2006-100, "Monticello Nozzle Inner Corner Region and Nozzle-to-Shell Weld Examinations, dated January 2006.

7. EPRI Report 3002002623, BWRVIP-190 Revision 1: BWR Vessel and Internals Project, Volume 1: BWR Water Chemistry Guidelines - Mandatory, Needed, and Good Practice Guidance, dated April 2014.

8. NRC letter to Nuclear Management Company (NMC), "Monticello Nuclear Generating Plant (MNGP) -- Granting of Relief Regarding Limited Ultrasonic Examination Coverage of Five Welds (TAC No. MD6854)," dated May 19, 2008 (ADAMS Accession No. ML081050678).

9. NRC letter to NSPM, "Monticello Nuclear Generation Plant (MNGP) -- Request for Relief No. 19, Concerning Examination Coverage of Certain Reactor Vessel Nozzle-to-Vessel Welds (TAC No. ME3937)," dated December 21, 2010 (ADAMS Accession No. ML103400651).

10. NRC letter to NSPM, "Monticello Nuclear Generating Plant -- Relief from Examination Coverage Requirements of the American Society of Mechanical Engineer's Boiler and Pressure Vessel Code,Section XI for the Fourth 10-Year Inservice Inspection Program Interval (TAC No. MF2654)," dated August 13, 2014 (ADAMS Accession No. ML14211A071).

11. NRC letter to NSPM, Monticello Nuclear Generating Plant (MNGP) - Relief Request RR-009 Regarding Relief from Examination Coverage Requirements of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code for the Fifth 10-Year Inservice Inspection Program Interval (TAC No. MF4258), dated February 19, 2015 (ADAMS Accession No. ML1502A152).

12. NRC letter to NSPM, Monticello Nuclear Generating Plant - Request for Relief for Coverage of Nozzle-To-Vessel Weld Examinations (EPID L-2018-LLR-0072), dated June 12, 2019 (ADAMS Accession No. ML19148A694).

13. NRC Regulatory Guide 1.147, Revision 19, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," dated October 2019 (ADAMS Accession No. ML19128A244).

14. NRC Regulatory Guide 1.147, Revision 20, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," dated December 2021 (ADAMS Accession No. ML16321A336).

Page 8 of 8 ENCLOSURE, ATTACHMENT 1

MONTICELLO NUCLEAR GENERATING PLANT

10 CFR 50.55a Request RR-017

Inservice Inspection Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) during the Fifth Ten-Year Interval

SUMMARY

OF 2019, 2021 AND 2023 REFUELING OUTAGE EXAMS FOR WHICH ESSENTIALLY 100 PERCENT COVERAGE WAS NOT OBTAINED ON CATEGORY B-D NOZZLE-TO-VESSEL WELDS

(3 Pages Follow)

ENCLOSURE, ATTACHMENT 2

MONTICELLO NUCLEAR GENERATING PLANT

10 CFR 50.55a Request RR-017

Inservice Inspection Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) during the Fifth Ten-Year Interval

EXAM LIMITATIONS IMPOSED BY COMPONENT DESIGN AND CONSTRUCTION

(15 Pages Follow)

L-MT-24-001 NSPM Enclosure, Attachment 2

Exam Limitations Imposed by Component Design and Construction

This attachment contains a series of excerpts from the Inservice Inspection (ISI) Ultrasonic Testing (UT) reports applicable to the subject components.

These excerpts contain sketches depicting the component configuration with physical limitations imposed by the design, e.g., geometrical contour and weld position. The sketches provide a cross sectional view depicting the UT coverage and the coverage limitations in relation to the required examination volume.

Descriptive details are also included with the sketches to provide reference to the configuration, e.g., interior/exterior surface, shell side / nozzle side of weld, weld area, required exam volume, area of coverage, etc.

RFO 29 (2019 Refueling Outage)

Component Report No. Page(s)

N-3C NV 2019UT002 Pages 2-3 N-4B NV 2019UT005 Pages 4-5 N-10 NV 2019UT018 Pages 6-7

RFO 30 (2021 Refueling Outage)

Component Report No. Page(s)

N-2G NV 2021UT048 Pages 8-9 N-6A NV 2021UT025 Pages 10-11 N-7 NV 2021UT024 Pages 12-13

RFO 31 (2023 Refueling Outage)

Component Report No. Page(s)

N-4D NV MN-23-UT-015 Pages 14-15

Page 1 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-3C NV Report No. 2019UT002 Axial (Radial) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Shaded area indicates coverage obtained.

Page 2 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-3C NV Report No. 2019UT002 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates exam area of coverage obtained. Report No. 2019UT001 reflects essentially 100% coverage of the inner 15% was obtained.

Page 3 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-4B NV Report No. 2019UT005 Axial Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates area of coverage obtained.

Page 4 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-4B NV Report No. 2019UT005 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates exam area of coverage obtained. Report No. 2019UT006 reflects essentially 100% coverage of the inner 15% was obtained.

Page 5 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-10 NV Report No. 2019UT018 Axial Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates exam area of coverage obtained.

Page 6 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-10 NV Report No. 2019UT018 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Shaded area indicates coverage obtained. Report 2019UT014 reflects essentially 100% coverage of the inner 15% was obtained.

Page 7 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-2G NV Report No. 2021UT048 Axial Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Bold outlined area indicates exam area of coverage obtained.

Page 8 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-2G NV Report No. 2021UT048 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates exam area of coverage obtained. Report 2021UT047 reflects essentially 100% coverage of the inner 15% was obtained.

Page 9 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-6A NV Report No. 2021UT025 Axial Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Bold outlined area indicates exam area of coverage obtained.

Page 10 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-6A NV Report No. 2021UT025 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Shaded and bold areas reflect the area of coverage obtained. Report 2021UT034 reflects essentially 100% coverage of the inner 15% was obtained.

Page 11 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-7 NV Report No. 2021UT024 Axial Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern and bold outline area indicates the exam area of coverage obtained.

Page 12 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-7 NV Report No. 2021UT024 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Shaded and bold outlined area indicates area of coverage obtained. Report 2021UT033 reflects essentially 100% coverage of the inner 15% was obtained.

Page 13 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-4D NV Report No. MN-23-UT015 Axial Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates the exam area of coverage obtained.

Page 14 of 15 L-MT-24-001 NSPM Enclosure, Attachment 2

Component N-4D NV Report No. MN-23-UT015 Parallel (Circular) Scan Plot

NOTES:

Weld Region: B-C-F-G Shell Region: C-D-E-F Nozzle Cylinder Region: A-B-G-H Required Exam Volume: A-B-C-D-E-F-G-H Vessel Exterior Surface: A-B-C-D Vessel Interior Surface: E-F-H-G Area of Exam Coverage Obtained: Slashed pattern area indicates the exam area of coverage obtained. Report MN-23-UT-011 reflects essentially 100% coverage of the inner 15% was obtained.

Page 15 of 15 ENCLOSURE, ATTACHMENT 3

MONTICELLO NUCLEAR GENERATING PLANT

10 CFR 50.55a Request RR-017

Inservice Inspection Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) during the Fifth Ten-Year Interval

SUMMARY

OF PAST 4TH AND 5TH INTERVAL EXAMINATION RESULTS FOR WHICH THE NRC GRANTED RELIEF DUE TO EXAM LIMITATIONS

(3 Pages Follow)

L-MT-24-001 NSPM Enclosure, Attachment 3

Summary of 4th and 5th Interval Examination Results for which the NRC Granted Relief Due to Exam Limitations

Table D: Summary of 4th Interval Nozzle-to-Vessel Weld Examinations with Previously Granted NRC Relief for the Subject Welds in this Request

4th Interval Exam Exam 4th Interval Exam 10 CFR 50.55a 4th Interval NRC Weld Year Coverage Results Request Approval Date N-2G 2007 78% No flaw indications RR-15 May 19, 2008 (Reference 1) (Reference 2)

N-6A 2007 86% No flaw indications RR-15 May 19, 2008 (Reference 1) (Reference 2)

N-3C 2009 83% No flaw indications RR-19 December 21, 2010 (Reference 3) (Reference 4)

N-4B 2009 83% No flaw indications RR-19 December 21, 2010 (Reference 3) (Reference 4)

N-10 2009 85% No flaw indications RR-19 December 21, 2010 (Reference 3) (Reference 4)

N-7 2009 87% No flaw indications RR-19 December 21, 2010 (Reference 3) (Reference 4)

N-4D 2011 83% No flaw indications RR-21 August 18, 2014 (Reference 5) (Reference 6)

Table E: Summary of 5th Interval Nozzle-to-Vessel Weld Examinations to Date with Previously Granted NRC Relief Due to Exam Limitations

5th Interval 5th Interval Exam Exam 5th Interval Exam 10 CFR 50.55a NRC Approval Weld Year Coverage Results Request Date N-1A 2013 83% No flaw indications RR-009 Feb. 19, 2015 (Reference 7) (Reference 8)

N-2D 2013 82% No flaw indications RR-009 Feb. 19, 2015 (Reference 7) (Reference 8)

N-4C 2013 79% No flaw indications RR-009 Feb. 19, 2015 (Reference 7) (Reference 8)

N-5B 2013 81% No flaw indications RR-009 Feb. 19, 2015 (Reference 7) (Reference 8)

N-8A 2013 83% No flaw indications RR-009 Feb. 19, 2015 (Reference 7) (Reference 8)

Page 1 of 3 L-MT-24-001 NSPM Enclosure, Attachment 3

5th Interval 5th Interval Exam Exam 5th Interval Exam 10 CFR 50.55a NRC Approval Weld Year Coverage Results Request Date N-2E NV 2017 83% No flaw indications RR-012 June 12, 2019 (Reference 9) (Reference 10)

N-4A NV 2017 83% No flaw indications RR-012 June 12, 2019 (Reference 9) (Reference 10)

N-9 NV 2017 85% No flaw indications RR-012 June 12, 2019 (Reference 9) (Reference 10)

REFERENCES FOR ENCLOSURE, ATTACHMENT 3

1. Nuclear Management Company (NMC) letter to the NRC, 10 CFR 50.55a Request No.

15: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval," dated September 26, 2007 (ADAMS Accession No. ML072710119).

2. NRC letter to Nuclear Management Company (NMC), Monticello Nuclear Generating Plant (MNGP) - Granting of Relief Regarding Limited Ultrasonic Examination Coverage of Five Welds (TAC No. MD6854)," dated May 19, 2008 (ADAMS Accession No. ML081050678).

3. NSPM letter to NRC, "10 CFR 50.55a Request No.19: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval," dated May 6, 2010 (ADAMS Accession No. ML101300050).

4. NRC letter to NSPM, "Monticello Nuclear Generation Plant (MNGP) - Request for Relief No. 19, Concerning Examination Coverage of Certain Reactor Vessel Nozzle-to-Vessel Welds (TAC No. ME3937)," dated December 21, 2010 (ADAMS Accession No. ML103400651).

5. NSPM letter to NRC, "10 CFR 50.55a Request No. 21: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.54a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval," dated August 28, 2013 (ADAMS Accession No. ML13241A236).

6. NRC letter to NSPM, "Monticello Nuclear Generating Plant - Relief from Examination Coverage Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI for the Fourth 10-Year Inservice Inspection Program Interval (TAC No. MF 2654)," dated August 13, 2014 (ADAMS Accession No. ML14211A071).

Page 2 of 3 L-MT-24-001 NSPM Enclosure, Attachment 3

7. NSPM letter to NRC, 10 CFR 50.55a Request No. 009: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fifth Ten-Year Inservice Inspection Interval," dated June 6, 2014 (ADAMS Accession No. ML14157A205).

8. NRC letter to NSPM, Monticello Nuclear Generating Plant - Relief Request RR-009 Regarding Relief from Examination Coverage Requirements of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code for the Fifth 10-Year Inservice Inspection Program Interval (TAC No. MF4258)," dated February 19, 2015 (ADAMS Accession No. ML15028A152).

9. NSPM letter to NRC, 10 CFR 50.55a Request RR-012: Inservice Inspection Impracticality in Accordance with 10 CFR 50.55a(g)(5)(iii) during the Fifth Ten-Year Interval," dated May 11, 2018 (ADAMS Accession No. ML18131A179).

10. NRC letter to NSPM, "Monticello Nuclear Generating Plant - Request for Relief for Coverage of Nozzle-To-Vessel Weld Examinations (EPID L-2018-LLR-0072)," dated June 12, 2019 (ADAMS Accession No. ML19148A694).

Page 3 of 3