ML24138A121

Alternative Request RR-002

ML24138A121
Person / Time
Site:	Monticello
Issue date:	07/02/2024
From:	Ballard B NRC/NRR/DORL/LPL3
To:	Hafen S Northern States Power Company, Minnesota
References
EPID L-2023-LLR-0036, RR-002
Download: ML24138A121 (1)

Text

July 2, 2024

MONTICELLO NUCLEAR GENER ATING PLANT - AUTHORIZATION AND SAFETY EVALUATION FOR 10 CFR 50.55a(z)(1) INSERVICE INSPECTION ALTERNATIVE REQUEST NO. RR-002 (EPID L-2023-LLR-0036)

LICENSEE INFORMATION

Recipients Name and Address: Shawn Hafen Site Vice President Northern States Power Company - Minnesota Monticello Nuclear Generating Plant 2807 West County Road 75 Monticello, MN 55362

Licensee: Northern States Power Company (NSPM)

Plant Name(s) and Unit(s): Monticello Nuclear Generating Plant ( Monticello)

Docket No.: 50-263

Renewed Operating License No.: DPR-22

APPLICATION INFORMATION

Submittal Date: July 11, 2023

Submittal Agencywide Documents Access and Management System (ADAMS) Accession No.: ML23193A799

Supplement Date: February 15, 2024

Supple ment ADAMS Accession No.: ML24046A132

Applicable Inservice Inspection (IS I) Interval Start/End Dates and License Expiration Date:The sixth 10-y ear ISI interval for M onticello began on June 1, 2023, and is scheduled to end on May 31, 203 3. Renewed Operating License No. DPR-22 for Monticello expires at midnight, September 8, 2030. This alternative request is applicable to those portions of the s ixth 10-y ear ISI Interval up to expiration of the current operating license at midnight on September 8, 2030.

Alternative Provision:The licensee requested an alternative under Title 10 of the Code of Federal Regulations (10 CFR), paragraph 50.55a(z)(1), Acceptable level of quality and safety.

ISI Requirements: The applicable ISI requirements are given in 10 CFR 50.55a, p aragraphs (g) and (z), and in the rules of the American Society of Mechanical Engineers Boiler and Pressure Vessel (ASME) Code,Section XI, Division 1 (henceforth, ASME Code,Section XI), as invoked for implementation by 10 CFR 50.55a(g). The regulations at 10 CFR 50.55a(z) permit the NRC staff toauthorize alternatives to the ISI requirements of ASME Code.Section XI, if : (1) the proposed alternative provides an acceptable level of quality and safety, or (2) compliance with the applicable ISI requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

The ISI rules in ASME Code,Section XI, Table IWB-2500-1, Examination Category B-D,

Inspection Items B3.90 and B3.100, require the licensee to perform volumetric inspections of essentially 100 percent of the required examination volume (defined as minimum 90 percent coverage by volume) of 100 percent of all accessible reactor pressure vessel (RPV) full penetration nozzle-to-vessel welds and nozzle inner blend radii locations once every 10-year ISI interval.

Note (6) to ASME 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 during the 10-year ISI interval down to a 25 percent population of inspected component locations if the conditions of ASME Code,Section XI, paragraph IWB -2500(f), subparagraphs (1) to (9), are met.

Applicable Code Edition and Addenda: ASME Code,Section XI, 2019 Edition.

Brief Description of the Proposed Alternative:

The licensee proposes that use of the 25 percent population of inspected components provisions in ASME Code,Section XI, p aragraph IWB-2500(f), be authorized for the nozzle-to-vessel full penetration welds and associated nozzle inner radii sections of the RPV N2, N3, N5, N6, and N8 nozzles, even though the maximum fluence referenced in IWB-2500(f)(8) and the maximum number of heatup/cooldown cycles referenced in IWB-2500(f)(9) will be exceeded at the end of a cumulative 60-year licensing term (i.e., at the end of 54 effective full power years (EFPY), as associated with the September 8, 2030, expiration date for Renewed License DPR-22). Specifically:

(1) The projected peak neutron fluence exposure at inside surface of the limiting N2 RPV nozzles of 1.01 x1018 n/cm2 (E > 1.0 MeV) exceeds the neutron fluence exposure limit of 1.0x1017 n/cm2 (E > 1.0 MeV) in ASME Code,Section XI, paragraph IWB -2500(f)(8).

(2) The cumulative number of heatup/cooldown cycles is projected to be 181 cycles, which exceeds the limit of 40 cycles set for plant heatup/cooldown cycles set in ASME Code,Section XI, paragraph IWB-2500(f)(9).

The licensee states that the proposed al ternative for a reduced 25 percent population of inspected RPV nozzles is supported by a plant-specific probabilistic fracture mechanics (PFM) analysis that was performed in accordance with the staff-approved guidelines in Electric Power Research Institute (EPRI) BWRVIP-108-A: BWR [b oiling-water reactor] Vessel and Internals Project, Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Blend Radii, (ML19297F806). The licensee states that if RR-002 is authorized by the NRC staff, the proposed alternative will provide an acceptable level of quality and safety, as required by 10 CFR 50.55a(z)(1).

STAFF EVALUATION

The NRC staffs review of NSPMs submittal included issuance of requests for additional information (RAIs), designated, RAI #RR-002-1, parts 1-3 and, RAI #RR -002-2, parts 1-4, by email dated January 20, 2024 (ML24022A021). The licensee supplemented their application by letter dated February 15, 2024, in response to the NRC staffs RAIs.

Staff Confirmation of Past MonticelloRR-002 ISI Alternative Precedents:

In Section 22 of the RR-002 submittal, the licensee notes that a similar ISI alternative was requested and approved for the f ifth 10-y ear ISI interval. The NRC staff verified NSPMs RR-002 request for the fifth10-y ear ISI interval, requested by letter dated September 28, 2011 (ML112720147), as supplemented by letters dated February 15, 2012 (ML120470088), and August 10, 2012 (ML12230A095); the NRC staff also confirmed that the RR-002 alternative request for the fifth10-y ear ISI interval was authorized by the NRC staff by letter dated August 28, 2012 (ML12236A280).

Scope of RR-002 - Period of Applicability and Differences from the RR -002 ISI Alternative authorized for the Fifth 10-Year ISI Interval:

The main difference in the 10 CFR 50.55a(z)(1) basis for the RR-002 alternative request for the sixth 10-year ISI interval when compared to the RR -002 alternative authorized for the fifth 10-year ISI interval is that the RR-002 alternative authorized for the fifth 10- year ISI interval was submitted in accordance with the ASME Code,Section XI, code case criteria in ASME Code Case N-702, which invokes the ISI alternative methods in the BWRVIP -108-A report. In contrast, the 10 CFR 50.55a(z)(1) basis for the R R-002 alternative request for the sixth 10-year ISI interval is in accordance with the provisions in ASME Code,Section XI, p aragraph IWB-2500(f), which allows examining a 25 percent population of RPV nozzle-to-vessel weld and nozzle inner blend radii locations during the 10-year ISI interval if the conditions in ASME Code,Section XI, p aragraph IWB-2500(f), subparagraphs (1) to (9), are met.

The NRC staff confirmed that, as is indicated in section 20 of RR-002 alternative request for the sixth ISI interval, the licensee still relies on the general concepts of the BWRVIP-108 -A alternate ISI provisions, as supported by the existing Monticello PFM analysis that was performed in Structural Integrity Associates (SIA) Calculation No. 1101463.301, M onticello N2 Nozzle Code Case N-702 Relief Request, and that is now modified by the specified conditions in the ASME Code,Section XI, p aragraph IWB-2500(f), provisions. 1 Given that the equivalent ASME Code ISI alternative provisions for a reduced 25 percent population of inspected nozzle locations have been appropriately defined in the ASME Code,Section XI, paragraph IWB -2500(f) provisions, the requirements in ASME Code,Section XI, p aragraph IWB-2500(f), subparagraphs (8) and (9), are the appropriate ASME Code,Section XI, requirements that apply to RR-002 ISI alternative for the s ixth 10-y ear ISI interval.

1 SIA Calculation No. 1101463.301, M onticello N2 Nozzle Code Case N-702 Relief Request, was included as Enclosure 1 of the February 15, 2012, supplement to NSPMs RR-002 alternative request for the fifth 10-y ear ISI interval. NSPMs August 10, 2012, supplement enclosed Revision 2 of the calculation, which was revised to include responses to the NRC staffs RAIs issued as part of the review of the RR-002 alternative request for the fifth 10-y ear ISI interval.

Scope of RR-002 - Nozzle Types, Nozzle Designations, Total Nozzle Populations, and Reduced Nozzle Populations for Inspection

The NRC staff observed that Section 17, Applicable ASME Components and/or System Description, of the licensees request identified that applicable nozzles within the scope of the request are the RPV N2, N3, N5, N6, and N8, nozzles, but did not specifically indicate which type of nozzles were associated with nozzle designations, provide the total population of specified nozzles that are included in the Monticello RPV design, or provide the actual number of nozzles that would be inspected for the specified nozzle designations. However, the staff noted that this information was previously docketed with the licensees RR-002 alternative request for the fifth 10-year ISI interval. In response to RAI #RR-002-2, parts 1 and 2, the licensee confirmed the information previously docketed is applicable to, part of, and valid for the RR-002 alternative request for the sixth 10-year ISI interval, as specified in the table below:

Minimum No. Minimum % of Nozzle Type Nozzle ID Nos. of Nozzles to Nozzles to be be Inspected Inspected N2 RPV Recirculation N2A, N2B, N2C, N2D, N2E, 3 of 10 30%

Inlet Nozzles N2F, N2G, N2H, N2J, N2K N3 RPV Main Steam N3A, N3B, N3C, N3D 1 of 4 25%

Line Nozzles N5 RPV Core Spray N5A, N5B 1 of 2 50%

Line Nozzles N6 RPV Closure Head N6A, N6B 1 of 2 50%

Spare Nozzles N8 RPV Jet Pump N8A, N8B 1 of 2 50%

Instrument Line Nozzles

The NRC staff finds the minimum number of RPV nozzle inside radius locations and nozzle-to-vessel welds that will be inspected for the specified nozzle types acceptable because: (1) the licensee will inspect a minimum 25 percent population of the RPV inside radius locations and 25 percent population of the nozzle-to-vessel welds for the specified RPV N2, N3, N5, N6, and N8, nozzle types during the sixth 10-year ISI interv al; and (2) the NRC staff has confirmed that this is consistent with the staffs approval of the specified RPV nozzle populations for RR-002 applying to fifth 10-year ISI interval.

Risk-Informed Basis for RR-002 - Applicable PFM Analysis, Impact of Past Inspection Results, and Demonstration of Acceptable Probability of Failure Values

The NRC staff confirmed that the risk -informed basis for the proposed reduction of volumetrically-inspected RPV nozzle weld and nozzle inner blend radii inspections is based on the risk-informed criteria for these types of ISI alternatives in BWRVIP-108 -A, which establishes that the conditional probability of failure (CPoF) of a RPV nozzle -to-vessel weld or nozzle inner blend radius location will be less than 1 x10-6; the BWRVIP-108-A methods were approved in the staffs safety evaluation (SE) of December 19, 2007, for the BWRVIP-108 report, which is included in BWRVIP-108-A. 2 The NRC staffs basis for accepting BWRVIP-108-A as a risk-informed methodology for reducing the number of inspected nozzle locations to a minimum 25

2 The CPoF is calculated from multiplying the probability of failure (PoF) for the evaluated nozzle-to-vessel weld or inner blend radius location by the probability of the initiating a low temperature, over pressure or pressurized thermal shock event (1x10 -3 per reactor year).

percent population is based on the staffs findings that the BWRVIP-108 -A methods satisfy the staffs upper bound CPoF value of 5x10-6 for occurrence of a postulated pressurized thermal shock event, as referenced in BWRVIP-108-A. A more detailed but concise summary of the BWRVIP-108-A risk-informed methods is given in section 3.2 of the staffs August 28, 2012, SE supporting authorization of RR-002 for the fifth10 -year ISI interval. The staffs December 19, 2007, SE for BWRVIP -108-A establishes that licensees must demonstrate applicability of the report to their plant by showing five general and nozzle specific criteria are satisfied. These criteria have now been replaced with the following conditions in ASME Section XI Paragraph IWB-2500(f), Subparagraphs (1) to (9), that must be met to allow for a reduced minimum 25 percent population of inspected nozzles (without the need for submitting a relief request alternative under the provision of 10 CFR 50.55a(z)(1)):

IWB-2500(f)(1): The nozzle types subject to the population reduction criteria must not include the RPV feedwater nozzles,

IWB-2500(f)(2): The provision of ASME Section XI, Appendix VIII must be used for the examinations.

IWB-2500(f)(3): Maximum RPV heatup/cooldown rate < 115 º F/hr

IWB-2500(f)(4): for bounding RPV i nlet nozzle locations:

(pr/t)/CRPV < 1.15, where

p = RPV normal operating pressure (psi),

r = RPV inner radius (inches),

t = RPV wall thickness (inches), and CRPV = 19332 (as a defined constant in U.S customary units)

IWB-2500(f)(5): for bounding RPV i nlet nozzle locations:

(p*(r02 + rI2)/(r02 - rI2))/C NOZZLE < 1.47, where

p = RPV normal operating pressure (psi),

r0 = RPV inlet nozzle outer radius (inches),

rI = RPV inlet nozzle inner radius (inches), and CNOZZLE = 1637 (as a defined constant in U.S. customary units)

IWB-2500(f)(6): for bounding RPV o utlet nozzle locations:

(pr/t)/CRPV < 1.15, where

p = RPV normal operating pressure (psi),

r = RPV inner radius (inches),

t = RPV wall thickness (inches), and CRPV = 16171 (as a defined constant in U.S. customary units)

IWB-2500(f)(7) : for bounding RPV o utlet nozzle locations:

(p*(r02 + rI2)/(r02 - rI2))/C NOZZLE < 1.59, where p = RPV normal operating pressure (psi),

r0 = RPV outlet nozzle outer radius (inches),

rI = RPV outlet nozzle inner radius (inches), and CNOZZLE = 1977 (as a defined constant in U.S. customary units)

IWB-2500(f)(8): The fluence level does not exceed a neutron fluence exposure of 1x10 17 n/cm2 (E >1.0 MeV) on any portion of the examined component.

IWB-2500(f)(9): The total number of heatup and cooldown cycles from plant startup for the component will not exceed 40 cycles by the end of the interval (with a cycle defined as consisting of both a heatup and cooldown of the reactor)

If these conditions are met, the provisions of ASME Section XI, Paragraph IWB -2500(f) establishes that the licensee has sufficient probabilistic basis for concluding that the PFM analyses of the RPV recirculation inlet and outlet are bounding PFM analyses for all other nozzles adjoined to the RPV (and would not be necessary for the remaining nozzles adjoined to the RPV), and that the populations of inspected RPV nozzle-to-vessel welds and inside radius sections can be reduced to minimum 25 percent population of inspected component without the need of a submitted relief request.

In regard to performance of the plant-specific PFM analysis (as performed in support of the plant-specific basis for meeting the specified I WB-2500(f) criteria), the NRC staff confirmed that the licensee previously submitted the applicable PFM analysis in SIA Calculation No.

1101463.301, as part of the August 10, 2012, supplement for the RR-002 alternative request for the fifth10-y ear ISI interval. In response to RAI #RR-002-2, Part 3, the licensee confirmed that the PFM analysis in SIA Calculation No. 1101463.301 is applicable to, part of, and valid for the RR-002 alternative request for the s ixth 10-y ear ISI interval. The licensee also provided the following additional information and clarifications in the licensees collective responses to RAI

1. RR-002-02, Part 3, and #RR-002-01, Parts 1 and 2:

• As reflected in the responses to RAI #RR-002-02, Part 3, and to #RR-002-01, Parts 1 and 2, the licensees past inspections of RPV nozzles required to be volumetrically-inspected (including N1, N2, N3, N5, N6, and N8 RPV nozzle types), and performed during the f ifth 10-y ear ISI interval did not reveal any flaw indications in the inside radius sections or nozzle-to-vessel welds of the nozzles.

• As reflected in the response to RAI #RR-002-02, Part 3, the end-of-life neutron fluence (i.e., 1.01 x 1018 n/cm2 [E > 1.0 MeV]) assumed in SIA Calculation No. 1101463.301 is more conservative and greater than the inside surface neutron fluence of 7.08 x 10 17 n/cm2 [E > 1.0 MeV] projected for the Monticello RPV at end of 80 years of plant operations (i.e., at 72 EFPY). 3

• As reflected in the response to RAI #RR-002-02, Part 3, Monticello has undergone of total of 156 plant startup/shutdown cycles as of June 2023 and is projected to undergo 176 startup/shutdown cycles through the end of the current, first renewed operating

3 As reported in Table 4.2.1.1-3 of the subsequent license renewal application (SLRA) for Monticello, dated January 9, 2023 ( ML23009A354).

license; this is lower than the 288 startup/shutdown cycles assumed in SIA Calculation No. 1101463.301. The staff notes the number of cycles estimated in response to the RAI is less than the number of cycles estimated in the RR -002 submittal of 181 cycles.

However, both estimates are significantly (>100 cycles) below the number of cycles assumed in SIA Calculation No. 1101463.301.

• As reflected in the response to RAI #RR-002-02, Part 3, the adjusted reference temperatures (ART) calculated in the PFM runs are fluence-based inputs in the PFM analysis and are calculated in accordance with NRC Regulatory Guide 1.99, Revision 2, methods; therefore, the KIc fracture toughness values used in the PFM calculations are adjusted based on actual fluence values (i.e., K Ic values less than 200 kilopound per square inch are used for calculation runs involving higher fluence values in the PFM analysis).

In regard to satisfying the conditions of IWB -2500(f), the staff confirmed that the licensee included its BWRVIP-108-A criterion assessments of parameters, now conditions of subparagraphs (3) to (7) of ASME Section XI, Paragraph IWB-2500(f), in Attachment 2 of the RR-002 alternative request for the f ifth 10-y ear ISI interval. In the licensees response to RAI

1. RR-002-2, Part 4, the licensee confirmed that BWRVIP -108 -A criterion assessments previously provided are applicable to, part of, and valid for the new RR -002 alternative request for the s ixth 10-y ear ISI interval.

Thus, based on the clarifications and confirmations discussed in the above, the NRC staff concluded that the PFM analysis in SIA Calculation No. 1101463.301 remains bounding for the following ASME Section XI, Paragraph IWB-2500(f) conditions needing assessment by the licensee for the sixth ISI interval alternative request, as supported by the following confirmatory observations noted by the staff:

• For IWB-2500(f)(1), staff confirmed that RPV feedwater nozzles are not part of the licensees request.

• For IWB-2500(f)(2), staff confirmed that the provisions of ASME Section XI, Appendix VIII are being used for implementation of the UT examinations perform on the nozzle welds and nozzle insider radius sections.

• For IWB-2500(f)(3), staff confirmed that the Monticello Technical Specification 5.6.5.b limits the RCS heatup and cooldown rates to a maximum rate change 100 º F/hr in any 1-hour period, as established and incorporated into the current licensing basis through reference to the staff-approved pressure-temperature limits report (PTLR) methodology in SIA Report No. SIR-05 -044-A, Revision 0, Pressure-Temperature Limits Report Methodology for Boiling Water Reactors, (ML072340283).

• For IWB-2500(f)(4), applying the N2 RPV recirculation inlet nozzles, staff confirmed that the licensee meets the condition through calculation of a (pr/t)/CRPV parameter value of 1.074; this demonstrates that the supporting PFM meets the upper bound limit of 1.15 set for this criterion parameter (as applicable to the RPV recirculation inlet nozzles).

• For IWB-2500(f)(5), applying the N2 recirculation inlet nozzles, staff confirm ed that the licensee meets the condition through calculation of a (p*(r02 + rI2)/(r02 - rI2))/CNOZZLE parameter value of 1.039; this demonstrates that the supporting PFM meets the upper

bound limit of 1.47 set for this criterion parameter (as applicable to the RPV recirculation inlet nozzles).

• For IWB-2500(f)(7), applying the N1 recirculation outlet nozzles, staff confirm ed that the licensee meets the condition through calculation of a (p*(r02 + rI2)/(r02 - rI2))/CNOZZLE parameter value of 0.936; this demonstrates that the supporting PFM meets the upper bound limit of 1.59 set for this criterion parameter (as applicable to the RPV recirculation outlet nozzles).

For IWB-2500(f)(6), applying the N1 recirculation outlet nozzles, the NRC staff observed and reconfirmed that the prior assessment of the criterion in Attachment 2 of the RR-002 alternative request for the fifth10-y ear ISI interval did not pass the upper bound limit of 1.15 set for the (pr/t)/C RPV parameter of this condition. The licensees calculated value was 1.283 for this parameter. In its response to RAI #RR -002-1, Part 2, the licensee confirmed that the N1 RPV recirculation outlet nozzles are still outside of the proposed alternative in RR -002 for the s ixth 10-y ear ISI interval and that essentially 100 percent of the volumes (minimum 90 percent coverage) in 100 percent of the accessible nozzle -to-vessel welds and nozzle inner blend radii locations of the RPV N1 recirculation outlet nozzles will be volumetrically -inspected during the sixth 10-y ear ISI interval for Monticello. The NRC staff finds this to be acceptable because the licensees response provides sufficient demonstration that the licensee will perform its volumetric inspections of the RPV N1 recirculation outlet nozzles in accordance with the ISI requirements in ASME Code,Section XI, Table IWB-2500-1, Examination Category B-D, Inspection Items B3.90 and B3.100, for the portions of the s ixth 10-y ear ISI interval in RR-002.

For IWB-2500(f)(8) and IWB-2500(f)(9), the staff observed that the projected neutron fluence and projected number of heatup/cooldown cycles exceeds the neutron fluence exposure limit of 1.0x1017 n/cm2 (E > 1.0 MeV) and maximum of 40 heatup/cooldown cycles in conditions IWB-2500(f)(8) and IWB-2500(f)(9), respectively. The staff notes the criterion in BWRVIP -108-A established that the projected neutron fluence exposures for the nozzle locations at the end of a 40-year design life should be negligible. As discussed above, the plant specific PFM analysis in SIA Calculation No. 1101463.301 assumes an end-of-life neutron fluence and heatup/cooldown cycles that exceed the projected values for Monticello. Using these values, the analysis indicates that the average probability of failure for the nozzle blend radii is 1.17x10 -7 per year for normal operation and 1.05x10-6 per year for the low temperature overpressure transient, considering 60 years of operation. For the nozzle-to-shell weld, the average probability of failure is 2.25x10-6 per year for normal operation and 1.69x10 -9 per year for the low temperature overpressure transient, considering 60 years of operation. The NRC staff finds the PFM analysis in SIA Calculation No. 1101463.301 supports the proposed reduction to 25 percent population of RPV nozzles because all of the calculated values are less than the NRC safety goal of 5x10 -6 per year for the pressurized thermal shock transient, and therefore finds the use of the provisions of IWB-2500(f), with fluence and heatup/cooldown cycles in excess of those specified in IWB-2500(f)(8) and (9), to be acceptable.

Given that the proposed RR-002 for the s ixth 10-y ear ISI interval still meets the upper bound limits of IWB-2500(f)(4) and (5) applying to the N2 RPV recirculation inlet nozzles, the staff finds that: (1) the PFM analysis performed for the N2 RPV recirculation inlet nozzles in SIA Calculation No. 1101463.301 remains bounding for PFM considerations of the N3 RPV main steam line nozzles, N5 RPV core spray nozzles, N6 RPV upper closure head spare nozzles, and N8 RPV jet pump instrument nozzles, and (2) performance of nozzle-specific PFM analyses of the RPV N3, N5, N6, and N8 nozzle types is not necessary for the portions of the sixth 10-year ISI interval that is within the scope of RR-002.

Given the NRC staffassessments described and provided above, the staff finds alternative RR-002 for the s ixth 10-y ear ISI Interval and the Monticello-specific PFM analysis basis in SIA Calculation No. 1101463.301 to be acceptable because the calculation supports the staff s findings that:

(1) the CPoF value for the nozzle-to-vessel welds and nozzle inner blend radius locations of the RPV N2, N3, N5, N6, and N8, nozzle types (as calculated by the licensee) will be less than the NRC staffs bounding CPoF value of 5x10 -6 per year, as referenced in BWRVIP-108-A,

(2) the ISI alternative provides an acceptable level of quality and safety in lieu of complying with the applicable requirements of ASME Code,Section XI, p aragraph IWB-2500(f) and ASME Code,Section XI, Table IWB-2500-1, Examination Category B-D, Inspection Items B3.90 and B3.100, as relative to the performance of volumetric inspections of nozzle-to-vessel weld and inner blend radius locations of the RPV N2 recirculation inlet nozzles, N3 main steam line nozzles, N5 core spray nozzles, N6 upper closure head spare nozzles, and N8 jet pump instrument nozzles, and

(3) the required populations of inspected RPV nozzle-to-vessel welds and nozzle inner blend radius section s may be reduced to a minimum 25 percent population of the total populations of RPV N2, N3, N5, N6, and N8 nozzles specified in this SE.

CONCLUSION

As set forth above, the NRC staff has determined that the proposed alternative provides an acceptable level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 5 0.55a(z)(1).

Therefore, the NRC staff authorizes the use of proposed alternative RR-002 at Monticello for the portion of the s ixth 10-y ear ISI interval up to the end of Renewed Operating License DPR-22, scheduled to expire at midnight, September 8, 2030. A new alternative request with a revised plant-specific PFM analysis will be required to implement this alternative for those portions of the sixth ISI interval (scheduled to end on May 31, 2033) beyond September 8, 2030, should the Monticello SLRA be approved.

All other ASME Code,Section XI, requirements for which an alternative was not specifically requested and authorized remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.

Principal Contributor: JMedoff, NRR

Date: July 2, 2024

Jeff Whited, Chief Plant Licensing Branch LPL3 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

cc: Listserv

ML24138A121 OFFICE NRR/DORL/LPL3/PM NRR/DNRL/NVIB/BC NRR/DORL/LPL3/LA NAME BBallard ABuford SRohrer DATE 5/16/2024 5/3/2024 5/21/2024 OFFICE NRR/DORL/LPL3/BC NAME Jeff Whited DATE 7/2/2024