RS-24-038, Relief Request Concerning Extension of Permanent Relief from Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds

Relief Request Concerning Extension of Permanent Relief from Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds

ML24123A119
Person / Time
Site:	LaSalle, Limerick, Nine Mile Point
Issue date:	05/02/2024
From:	David Gudger Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-24-038
Download: ML24123A119 (1)

Text

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Request for Alternative to the Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds May 2, 2024 Page 2

Attachment:

Request for Alternative to the Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds

cc: Regional Administrator - NRC Region I Regional Administrator - NRC Region III NRC Senior Resident Inspector - LaSalle County Station NRC Senior Resident Inspector - Limerick Generating Station NRC Senior Resident Inspector - Nine Mile Point Nuclear Station NRC Project Manager - LaSalle County Station NRC Project Manager - Limerick Generating Station NRC Project Manager - Nine Mile Point Nuclear Station Attachment Request for Alternative to the Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds 10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 1 of 7)

Proposed Alternative to the Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds in Accordance with 10 CFR 50.55a(z)(1)

1. ASME Code Component(s) Affected:

Component: Reactor Pressure Vessel (RPV)

Code Class: 1 Examination Category: B-A Item No.: B1.11

Description:

Circumferential Pressure Retaining Welds in Reactor Vessel

2. Applicable Code Edition and Addenda:

PLANT INTERVAL EDITION START END

LaSalle County Station, Fourth 2007 Edition, through October 1, 2017 September 30, 2027 Units 1 and 2 2008 Addenda Limerick Generating Fourth 2007 Edition, through February 1, 2017 January 31, 2027 Station, Units 1 and 2 2008 Addenda Nine Mile Point Nuclear Fourth 2013 Edition October 6, 2018 August 22, 2028 Station, Unit 2

3. Applicable Code Requirements

ASME Section XI, Section IWB-2500 and Table IWB-2500-1, Examination Category B -A, Item Number B1.11 (2007 Edition with 2008 Addenda and 2013 Edition) requires volumetric examination of all RPV circumferential pressure retaining welds each inspection interval.

4. Reason for Request:

Constellation Energy Generation, LLC (CEG ) has previously utilized BWRVIP A, BWR Vessel and Internals Project BWR Reactor Pressure Vessel Inspection and Flaw Evaluation Guidelines for License Renewal, or BWRVIP-05, BWR Vessel and Internals Project, BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations, to obtain examination relief of RPV beltline circumferential welds and to address embrittlement of RPV beltline axial welds during extended plant operation. The U.S. Nuclear Regulatory Commiss ion (NRC) safety evaluation (SE) of BWRVIP-74-A issued October 18, 2001 (Reference 3) specified actions to obtain examination relief of RPV beltline circumferential welds and to monitor embrittlement of RPV beltline axial welds, both of which were based on results of probabilistic fracture mechanics (PFM) analyses in the staffs SE and supplemental SE of BWRVIP-05. As stated in BWRVIP -329, the objective of the report is to use NRC safety goals and PFM analysis procedures that have been developed since the publication of BWRVIP-05 to update the evaluation procedure and acceptance criteria specified in

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 2 of 7)

BWRVIP-74 -A for providing relief from examination of RPV circumferential welds and assessing axial weld integrity.

By letter dated August 22, 2019 (Referenc e 1), the Electric Power Research Institute (EPRI) submitted to the NRC for review BWRVIP-329, Updated Probabilistic Fracture Mechanics Analyses for BWR RPV Welds to Address Extended Operations. NRC acceptance is documented in the email from J. Holonich (U.S. Nuclear Regulatory Commission) to D.

Rouse and W. McGruder (Electric Power Research Institute), BWRVIP-329 Final Safety Evaluation, dated April 21, 2021 (Reference 2).

In BWRVIP-329-A, a PFM analysis was performed to identify the combination of RPV beltline material conditions that would ensure NRC safety goals are satisfied for RPVs for a postulated, low temperature isothermal pressure transient, which had been determined to dominate the BWR RPV failure frequency. The methodology for this PFM analysis is consistent with previous industry and regulatory evaluations but applies more recent analysis procedures. T he results of the PFM analysis identify the combination of beltline material conditions for the BWR fleet that will ensure regulatory safety goals are satisfied for the postulated transient. Section 3 and Section 4 of BWRVIP -329-A provide the complete details of the PFM analysis and inputs as well as the PFM analysis results. The PFM results are used to demonstrate that RPVs in the BWR fleet have margin against failure and satisfy NRC safety goals through at least 80-years of operating for the postulated transient.

BWRVIP-329-A demonstrates that the RPVs included in this proposed alternative have margin against failure and satisfy NRC safety goals for the postulated transient. Application of BWRVIP-329-A provides continuing basis to justify relief from examination of RPV circumferential welds (B-A, B1.11) and demonstrates acceptable integrity of RPV axial welds.

This proposed alternative also serves to satisfy any applicable license renewal commitments associated with RPV circumferential and axial weld inspections which may include submittal of an amended relief request in accordance with the requirements of 10 CFR 50.55a to obtain continued relief from the subject ASME Code inspection requirements through the period of extended operation.

5. Proposed Alternative and Basis for Use:

CEG is requesting relief from the ultrasonic examination requirements of ASME Section XI, Table IWB-2500-1, Examination Category B -A, Item No. B1.11 circumferential pressure retaining welds in RPVs, for the units identified in Section 2, based upon the PFM analysis methodology, results, and conclusions of BWRVIP-329-A. CEG will continue to com ply with all other applicable ASME Section XI examination requirements associated with the RPVs including inspection of the RPV vertical pressure retaining welds (Category B -A, Item No.

B1.12) and performance of the Class 1 system leakage test (Category B -P, Item Nos.

B15.10 & B15.20) each refueling outage.

In BWRVIP-329-A, a bounding PFM analysis was performed to evaluate the safety significance of a postulated, low temperature isothermal pressure transient in BWR RPVs; identify the combination of beltline material conditions that will ensure regulatory safety goals are satisfied for the postulated transient; and determine if there is adequate margin against vessel failure during the postulated transient.

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 3 of 7)

Table 5-1 in Section 5 of BWRVIP -329-A provides a means to verify that the PFM analysis documented in BWRVIP-329-A is applicable to a specific BWR RPV. BWRVIP-329-A states that since the evaluation approach explicitly considered the RPV dimensions of all U.S.

BWRs, these plants are by definition envel oped by this study. Table 1 below identifies the site-specific dimensions for the CEG Units included in this proposed alternative in order to demonstrate that they are bounded by the RPV dimensions in Table 5-1 of BWRVIP -329-A.

Table 1: Site Specific Information for Verification of Vessel Dimensions

Dimension LaSalle LaSalle Limerick Limerick Nine Mile Point Unit 1 Unit 2 Unit 1 Unit 2 Unit 2 Reactor Vessel Inside 127.0 126.7 126.7 126.7 126.7 Radius to CBMI, in.

Base Metal Wall 6.1 6.4 6.4 6.4 6.4 Thickness, in.

Radius / thickness 20.7 19.7 19.7 19.7 19.7 Cladding Thickness, in. 5/16 3/16 3/16 3/16 3/16

Table 5-2 in Section 5 of BWRVIP-329-A provides a template for showing that the plant-specific limiting RPV beltline mean reference temperature at the vessel inner surface (RTMAX) values are less than the limiting RTMAX values analyzed in BWRVIP-329-A, therefore demonstrating that the plant-specific conditional probability of failure (CPF ) values through the extended period of operation are below the acceptance criteria defined in the Technical Report. This plant-specific comparison for the requested CEG Units is shown in Table 2 through 6 below. Table 5-2 of BWRVIP-329-A contains the limiting RTmax value based on Category 1 and Category 2 Vessels. As used in Table 5-2 of BWRVIP-329-A, LaSalle Unit 1, LaSalle Unit 2, and Nine Mile Point Unit 2 are Category 1 Vessels ; Limerick Unit 1 and Limerick Unit 2 are Category 2 Vessels.

Table 2: LaSalle County Station (LCS), Unit 1 Parameter Verification

LCS, Unit 1 Parameter Limiting Plate Limiting Limiting Axial Weld Circumferential Weld Heat/Lot Identification C6345-1 6329637 1P3571 Number Copper Content (wt. %) 0.14* 0.205 0.21*

Nickel Content (wt. ) 0.54* 0.105 0.75*

Chemistry Factor (CF) (F) 1 152* 8 440*

EOI Neutron Fluence (f).77E 17 8.45E 17 8.23E 17 (n cm2) 2 RTNDT(U) (F) 3 20 50 30 EOI ¨RTNDT (F) 4 63 38 167 EOI RTMAX (F) 5 43 12 137 Category 1 Vessel Limiting See BWRVIP 32 See BWRVIP 32 A See BWRVIP 32 A RTMAX (F) 6 A Table 5 2 Table 5 2 Table 5 2 EOI RTMAX Limiting Yes Yes Yes RTMAX" 7

• Values for limiting plate and axial weld are based upon test data included in the Integrated Surveillance Program as documented in BWRVIP 135 Revision 4.

Note: Values were taken from the LaSalle County Generating Station Units 1 and 2 Pressure and Temperature Limits Report (PTLR) for 54 Effective Full Power Years (EFPY) submitted to the NRC in support of a License Amendment Request dated 11 10 2022 (ML22332A44 ) and supplemented 1 10 2023 (ML23010A227).

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 4 of 7)

Table 3: LaSalle County Station (LCS), Unit 2 Parameter Verification

LCS, Unit 2 Parameter Limiting Plate Limiting Limiting Axial Circumferential Weld Weld Heat/Lot Identification Number C9404-2 5P6771/342 3P4966/1214 Copper Content (wt. %) 0.07 0.034* 0.025*

Nickel Content (wt. %) 0.49 0.934* 0.913*

Chemistry Factor (CF) (°F) 1 44 46* 34*

EOI Neutron Fluence (f) (n/cm2) 2 1.07E+18 9.11E+17 1.01E+18 RTNDT(U) (°F) 3 52 -34 -6 EOI RTNDT (°F) 4 19 18 14 EOI RTMAX (°F) 5 71 -16 8 Category 1 Vessel Limiting RTMAX See BWRVIP-See BWRVIP-329-A See BWRVIP-329-(°F) 6 329-A Table 5-2 Table 5-2 A Table 5-2 EOI RTMAX < Limiting RTMAX? 7 Yes Yes Yes

• Values for limiting circumferential weld and axial weld are based upon best estimate chemistry values as documented in BWRVIP-135 Revision 4.

Note: Values were taken from the LaSalle County Generating Station Units 1 and 2 Pressure and Temperature Limits Report (PTLR) for 54 Effective Full-Power Years (EFPY) submitted to the NRC in support of a License Amendment Request dated 11/10/2022 (ML22332A449) and supplemented 1/10/2023 (ML23010A227).

Table 4: Limerick Generating Station (LGS), Unit 1 Parameter Verification

LGS, Unit 1 Parameter Limiting Plate Limiting Limiting Axial Circumferential Weld Weld Heat/Lot Identification Number C7677-1 07L857/B101A27A 662A746/H013A27A Copper Content (wt. %) 0.11 0.03 0.03 Nickel Content (wt. %) 0.50 0.97 0.88 Chemistry Factor (CF) (°F) 1 73 41 41 EOI Neutron Fluence (f) (n/cm2) 2 1.09E+18 8.08E+17 8.89E+17 RTNDT(U) (°F) 3 20 -6 -20 EOI RTNDT (°F) 4 32 15 16 EOI RTMAX (°F) 5 52 9 -4 Category 2 Vessel Limiting RTMAX See BWRVIP-See BWRVIP-329-A See BWRVIP-329-(°F) 6 329-A Table 5-2 Table 5-2 A Table 5-2 EOI RTMAX < Limiting RTMAX? 7 Yes Yes Yes Note: Values were taken from the Limerick Generating Station Unit 1 Pressure and Temperature Limits Report (PTLR) for 57 Effective Full-Power Years (EFPY) submitted to the NRC in support of a License Amendment Request dated 9/29/2020 (ML20273A215).

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 5 of 7)

Table 5: Limerick Generating Station, Unit 2 Parameter Verification

LGS, Unit 2 Parameter Limiting Plate Limiting Limiting Axial Circumferential Weld Weld Heat/Lot Identification Number B3416-1 07L857/B101A27A 432A2671/

H019A27A Copper Content (wt. %) 0.14 0.03 0.04 Nickel Content (wt. %) 0.65 0.97 1.08 Chemistry Factor (CF) (°F) 1 101 41 54 EOI Neutron Fluence (f) (n/cm2) 2 7.69E+17 7.69E+17 8.71E+17 RTNDT(U) (°F) 3 40 -6 -12 EOI RTNDT (°F) 4 37 15 21 EOI RTMAX (°F) 5 77 9 9 Category 2 Vessel Limiting RTMAX See BWRVIP-See BWRVIP-329-A See BWRVIP-329-(°F) 6 329-A Table 5-2 Table 5-2 A Table 5-2 EOI RTMAX < Limiting RTMAX? 7 Yes Yes Yes Note: Values were taken from the Limerick Generating Station Unit 2 Pressure and Temperature Limits Report (PTLR) for 57 Effective Full-Power Years (EFPY) submitted to the NRC in support of a License Amendment Request dated 9/29/2020 (ML20273A215).

Table 6: Nine Mile Point Nuclear Station (NMP), Unit 2 Parameter Verification

NMP, Unit 2 Parameter Limiting Plate Limiting Limiting Axial Circumferential Weld Weld Heat/Lot Identification Number C3147-1 4P7216(S)/0751 5P5657(S)/0931 Copper Content (wt. %) 0.11 0.045 0.07 Nickel Content (wt. %) 0.63 0.80 0.71 Chemistry Factor (CF) (°F) 1 74.5 61 95 EOI Neutron Fluence (f) (n/cm2) 2 1.62E+18 1.58E+18 1.62E+18 RTNDT(U) (°F) 3 0 -50 -60 EOI RTNDT (°F) 4 39 32 50 EOI RTMAX (°F) 5 39 -18 -10 Category 1 Vessel Limiting RTMAX See BWRVIP-See BWRVIP-329-A See BWRVIP-329-(°F) 6 329-A Table 5-2 Table 5-2 A Table 5-2 EOI RTMAX < Limiting RTMAX? 7 Yes Yes Yes Note: Values were taken from the Nine Mile Point Unit 2 Pressure and Temperature Limits Report, PTLR-2 approved by SER dated May 29, 2014 (ML14057A554).

Notes applicable to Table 2 through 6

1. Regulatory Guide 1.99 Chemistry Factor: Determined per Position 1.1 using Table 1 for Welds and Table 2 for Plates when less than two points of surveillance data are available or determined per position 2.1 when two or more points of surveillance data are available.

2. The end-of-interval (EOI) peak neutron fluence (E > 1.0 MeV) at the RPV inner surface for the limiting weld or plate being evaluated.

3. Unirradiated (initial) reference temperature.

4. Increase in reference temperature due to irradiation at end of the interval for which the analysis is to be applied: RTNDT = (CF) f(0.28-0.10 log f), where fluence (f) is expressed in units of 10 19 n/cm2 (E

> 1.0 MeV).

5. RTMAX at the end of the interval for which the analysis is to be applied: RT MAX = RTNDT(U) +

RTNDT.

6. Bounding RTMAX values that satisfy risk goals (from BWRVIP-329-A, Figure 4-3) For Category 1 Vessels, RTMAX values are set to ensure Total CPF 1E-3. For Category 2 vessels, RTMAX values are set to ensure Total CPF 5E-4 which conservatively accounts for a potential increase in CPF for field-fabricated welds of ~1.4x.

7. If the EOI RTMAX values for the limiting plate, circumferential weld, and axial weld are ALL less 10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 6 of 7)

than the corresponding limiting RTMAX values, the safety goals defined by BWRVIP-329-A remain satisfied.

Table 1 of the proposed alternative demonstrates plant specific applicability of the PFM analysis in BWRVIP-329-A for LaSalle Units 1 and 2, Limerick Units 1 and 2, and Nine Mile Point Unit 2. Table 2 through 6 of the proposed alternative demonstrates th at the plant-specific limiting RPV beltline RTMAX values are less than the limiting RTMAX values analyzed in BWRVIP-329-A for LaSalle Units 1 and 2, Limerick Units 1 and 2, and Nine Mile Point Unit 2. Therefore, the safety goals defined in Section 4 of BWRVIP -329 -A are met. Based on the information presented, BWRVIP -329-A provides an acceptable technical basis for continued relief from the ASME Code,Section XI examinations for the RPV circumferential welds, provides an acceptable technical evaluation for the embrittlement of RPV axial welds,

and demonstrates an acceptable level of quality and safety for the duration of the proposed alternative.

6. Duration of Proposed Alternative:

The proposed alternative is requested for the remainder of the renewed facility operating license as shown in the table below.

PLANT END OF EXTENDED ANALYZED OPERATING LICENSE EFFECTIVE FULL POWER YEARS (EFPYs)

LaSalle County Station, Unit 1 April 17, 2042 54

LaSalle County Station, Unit 2 December 16, 2043 54

Limerick Generating Station, Unit 1 October 26, 2044 57

Limerick Generating Station, Unit 2 June 22, 2049 57

Nine Mile Point Nuclear Station, Unit 2 October 31, 2046 54

7. References

1. Letter from N. Palm (Electric Power Research Institute) to J. Holonich (U.S. Nuclear Regulatory Commission), Transmittal of BWRVIP-329: BWR Vessel and Internals Project, Updated Probabilistic Fracture Mechanics Analysis for BWR RPV Welds to Address Extended Operations," dated August 22, 2019 (ML19238A075).

2. Letter from J. Holonich (U.S. Nuclear Regulatory Commission) to D. Rouse and W.

McGruder (Electric Power Research Institute), BWRVIP-329 Final Safety Evaluation, dated April 12, 2021 (ML21084A088).

3. Letter from C. Grimes (U.S. Nuclear Regulatory Commission) to C. Terry (Niagara Mohawk Power Company), Acceptance for Referencing of EPRI Proprietary Report TR -

113596, BWR Vessel and Internals Project, BWR Reactor Pressure Vessel Inspection and Flaw Evaluation Guidelines (BWRVIP-74) and Appendix A, Demonstration of 10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 7 of 7)

Compliance with the Technical Information Requirements of the License Renewal Rule (10 CFR 54.21), dated October 18, 2001 (ML012920549).

8. Precedent:

None