RS-26-015, Bryon Station, Units 1 and 2 - Supplement Related to License Amendment Request for Proposed Change to Limitations and Conditions on Non-LOCA Transient/Accident Methodology
| ML26055A319 | |
| Person / Time | |
|---|---|
| Site: | Braidwood, Byron  (NPF-077, NPF-072, NPF-037, NPF-066) |
| Issue date: | 02/24/2026 |
| From: | Steinman R Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RS-26-015 | |
| Download: ML26055A319 (0) | |
Text
4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office Attachments 3 and 4 contain Proprietary Information. Withhold from public disclosure under 10 CFR 2.390. When separated from Attachments 3 and 4, this document is decontrolled.
RS-26-015 10 CFR 50.90 February 24, 2026 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Supplement Related to License Amendment Request for Proposed Change to Limitations and Conditions on Non-LOCA Transient/Accident Methodology
References:
- 1. CEG Letter RS-26-152, "License Amendment Request for Proposed Change to Limitations and Conditions on Non-LOCA Transient/Accident Methodology,"
dated November 12, 2025 (ADAMS Accession No. ML25318B207)
- 2. NRC Safety Evaluation Report, Braidwood Station, Units 1 and 2; and Byron Station, Units 1, and 2 - Issuance of Amendments to Revise Technical Specifications to use Framatome GAIA Fuel (EPID L-2024-LLA-0072), dated August 21, 2025 (ADAMS Accession No. ML25148A202)
Constellation Energy Generation, LLC (CEG) is submitting this supplement related to the license amendment request (LAR) for proposed changes to limitations and conditions (L&C) on non-LOCA transient/accident methodology for Braidwood Station, Units 1 and 2 (Braidwood) and Byron Station, Units 1 and 2 (Byron) (Reference 1). This supplement provides an updated methodology for the proposed changes to L&C #3 and #10, along with its supporting information.
Attachments 3 and 4 contain information proprietary to Framatome. The affidavit, provided in, sets forth the basis on which Framatome's information may be withheld from public disclosure by the NRC and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR 2.390, "Public inspections, exemptions, requests for withholding."
While the affidavit specifically references the report in Attachment 3, the content in Attachment 4 was either copied from Attachment 3 or previously withheld from public disclosure in Reference 1 and is therefore requested to remain withheld. Accordingly, it is respectfully requested that the information that is proprietary to Framatome be withheld from public disclosure in accordance with 10 CFR 2.390. Proprietary information is indicated by text enclosed within
February 24, 2026 U.S. Nuclear Regulatory Commission Page 2 Attachments 3 and 4 contain Proprietary Information. Withhold from public disclosure under 10 CFR 2.390. When separated from Attachments 3 and 4, this document is decontrolled.
[ bold brackets ]. Attachments 1 and 2 provide the non-proprietary versions of the description and evaluation of the proposed changes.
CEG requests the following update to the implementation period of this LAR, once approved.
The Braidwood amendments shall be implemented prior to their 2026 Unit 2 spring outage. The Byron amendments shall be implemented prior to their 2026 Unit 2 fall outage.
CEG has reviewed the information supporting the finding of no significant hazards consideration and the environmental consideration that were previously provided to the NRC in Reference 1.
The revised information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, the information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation,"
paragraph (b), CEG is notifying the State of Illinois of this supplement to the application for license amendment by transmitting a copy of this letter and its attachments to the designated State Official.
There are no regulatory commitments contained in this letter. Should you have any questions concerning this letter, please contact Brian Seawright at (779) 231-6151.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 24th day of February 2026.
Respectfully, Rebecca L. Steinman Senior Manager - Licensing Constellation Energy Generation, LLC Attachments:
- 1) Byron and Braidwood LAR Inputs (Non-Proprietary)
- 2) Summary of Proposed Changes to LAR (Non-Proprietary)
- 3) Byron and Braidwood LAR Inputs (Proprietary)
- 4) Summary of Proposed Changes to LAR (Proprietary)
NRC Regional Administrator, Region III NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station Illinois Emergency Management Agency - Division of Nuclear Safety Steinman, Rebecca Lee Digitally signed by Steinman, Rebecca Lee Date: 2026.02.24 13:29:06 -06'00'
Byron and Braidwood LAR Inputs (Non-Proprietary)
0414-12-F04 (Rev. 005, 04/10/2024)
Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Technical Report ANP-4184 Revision 0 Supplement 1NP Revision 0 February 2026 (c) 2026 Framatome Inc.
ANP-4184 Revision 0 Supplement 1NP Revision 0 0414-12-F04 (Rev. 005, 04/10/2024)
Copyright © 2026 Framatome Inc.
All Rights Reserved FRAMATOME TRADEMARKS ARITA, ARTEMIS, GAIA, and S-RELAP5 are trademarks or registered trademarks of Framatome or its affiliates, in the USA or other countries.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page i Nature of Changes Item Section(s) or Page(s)
Description and Justification 1
All Initial Issue
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page ii Contents Page
1.0 INTRODUCTION
............................................................................................... 1-1 2.0 ARITA L&C 10 UPDATED REQUEST AND SUPPLEMENTAL INFORMATION................................................................................................. 2-1 2.1 Updated Licensing Request Change to [
]...... 2-2 2.2 Background Information on [
]............................................................................................. 2-3 2.2.1 Additional Information Supporting Setting [
]
to Mean........................................................................................ 2-3 2.2.2 Justification of [
]............... 2-7 3.0 ARITA L&C 3 SUPPLEMENTAL INFORMATION............................................. 3-1 3.1
[
].................................................... 3-1 3.2
[
]..... 3-6
4.0 REFERENCES
.................................................................................................. 4-1
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page iii List of Figures Figure 3-1 [
]..... 3-9 Figure 3-2 [
]................................................ 3-10 Figure 3-3 [
]........... 3-11 Figure 3-4 [
].............. 3-12 Figure 3-5 [
]........................ 3-13 Figure 3-6 [
].................................... 3-14 Figure 3-7 [
].................................................................................. 3-15 Figure 3-8 [
]........... 3-16 Figure 3-9 [
]........................... 3-17 Figure 3-10 [
]........................................ 3-18 Figure 3-11 [
].............. 3-19 Figure 3-12 [
]............................... 3-20
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page iv Nomenclature Acronym Definition AO Axial Offset ARITA ARTEMIS/RELAP Integrated Transient Analysis ARO All Rods Out
[
]
[
]
DFTW Decrease in Feedwater Temperature DNB Departure from Nucleate Boiling DNBR Departure from Nucleate Boiling Ratio FCM Fuel Centerline Melt FOM Figure of Merit L&C Limitation and Condition LAR License Amendment Request LOCA Loss of Coolant Accident MDNBR Minimum Departure from Nucleate Boiling Ratio MSLB Main Steam Line Break MSSV Main Steam Safety Valve NRC Nuclear Regulatory Commission PIRT Phenomena Identification and Ranking Table PWR Pressurized Water Reactors RAI Request for Additional Information RCS Reactor Coolant System SER Safety Evaluation Report SG Steam Generator TCS Transient Cladding Strain TIC Time in Cycle UCBW Uncontrolled Bank Withdrawal
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 1-1
1.0 INTRODUCTION
This report provides supplemental information to support the Byron and Braidwood License Amendment Request (LAR) (Reference 1) to update the [
] (Section 2.0) and the ARITA sampling strategy (Section 3.0) that were used and approved for the Braidwood Station Units 1 and 2 and Byron Station Units 1 and 2 transition to Framatome GAIA fuel (Reference 6).
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-1 2.0 ARITA L&C 10 UPDATED REQUEST AND SUPPLEMENTAL INFORMATION The [
] is addressed in Limitation and Condition (L&C) 10 of the approved ARTEMIS/RELAP Integrated Transient Analysis (ARITA) Topical Report (Reference 4). In Reference 1, Framatome proposed modifying the [
] to its [
] submitted in 7 of Reference 5. During a Nuclear Regulatory Commission (NRC) audit,
[
] The supplemental information in this section [
]
Section 2.1 - This section provides the update to the proposed [
]
Section 2.2.1 - This section provides further justification supporting the [
] approach submitted in Reference 1 as requested during NRC audits.
Section 2.2.2 - This section provides justification for the updated [
] approach proposed in Section 2.1.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-2 2.1 Updated Licensing Request Change to [
]
Framatome proposes adjusting the [
] specified in L&C 10 (and updated in the LAR for Byron and Braidwood Fuel Transition to GAIA) based on [
]
Therefore, Framatome proposes that the [
] within the ARITA methodology for Byron and Braidwood Units 1 and 2 be updated as follows:
The corresponding [
]
It remains acceptable [
] This ensures analyses, which use these options, remain valid.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-3 2.2 Background Information on [
]
2.2.1 Additional Information Supporting Setting [
] to Mean This section provides further justification supporting the [
]
approach submitted in Reference 1 as requested during audits.
L&C 10 in the Safety Evaluation Report (SER) for the ARITA topical Report (Reference 4) addressed the [
] in the LAR for the Byron and Braidwood transition to Framatome fuel (Ref. 5). L&C 10 as stated in the SER for the ARITA topical report is as follows:
The parameter SEC-2b, [
] (Section 3.5.1.2, SEC-2b)
There are three requirements in L&C 10.
In the Byron and Braidwood LAR for the fuel transition to Framatome fuel the third requirement above was modified to [
]
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-4 Framatome believes that the [
]
- 1. In safety analysis, the transient analysis code is calibrated to measured steady-state plant conditions prior to initiating transient analyses. [
] is part of the modeling of the transfer of heat from the primary to secondary side. [
]
- 2. The [
] imposed by L&C 10 for the [
] is too large and contributes to the non-physical results seen from
[
] The imposed [
] in L&C 10 is derived from the assumption that
[
] Framatome [
]
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-5 The key to understanding this sentence is the [
] This sentence does not mean that the [
] but rather the [
] This is clear from a review of the referenced figures. It is also noted that Reference 2 is [
] for data was not common.
The interpretation of the meaning of the Reference 2 [
]
is also supported by Reference 3 where the abstract states:
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-6
[
] in Reference 3 provides an [
] the table provides the following values:
The fact that [
] in Reference 2 represents an [
]
Assuming that the values in [
]
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-7
[
] on the Departure from Nucleate Boiling (DNB), Fuel Centerline Melt (FCM), and Transient Cladding Strain (TCS) Figures of Merit (FOM) for Unit 1 confirm that when the [
] This is also consistent with the approach within the approved EMF-2310 Framatome methodology (Reference 7). On this basis, Framatome proposed [
] for ARITA applications to the Byron and Braidwood plants.
2.2.2 Justification of [
]
This information is provided to support timely completion of the current licensing action.
Framatomes technical position remains that [
] To facilitate resolution of the current review, Framatome is proposing
[
]
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-8 2.2.2.1 Clarification of PIRT Significance for Steam Generator Heat Transfer The PIRT process identified primary-to-secondary heat transfer as an important phenomenon influencing plant response. This identification is appropriate and reflects long-standing industry experience demonstrating that large physical changes in steam generator heat transfer capability can have a significant impact on plant operation and safety margins.
Historical operating experience illustrates this distinction clearly. During the 1990s, many PWRs experienced widespread degradation of Alloy 600 steam generator U-tubes, leading to extensive tube plugging over successive operating cycles. In some cases, more than ten percent of the tube population was removed from service, resulting in measurable reductions in effective heat transfer area and prompting industry-wide steam generator replacement programs utilizing Alloy 690 U-tubes. These examples demonstrate that substantial physical changes to steam generator configuration and heat transfer surface area can have first-order impacts on plant behavior.
The PIRT identification of primary-to-secondary heat transfer significance was not intended to imply that small variations in the convective heat transfer coefficient within a plant-calibrated evaluation model necessarily represent a dominant source of uncertainty for transient analyses. Rather, the PIRT identifies phenomena that must be appropriately represented in the analytical model, and the phenomena of primary-to-secondary heat transfer is treated by applying a bias to tune the model based on plant documentation.
In the present application, steam generator heat transfer is explicitly represented and calibrated to plant data, thereby capturing the dominant physical behavior identified by the PIRT.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-9 2.2.2.2 Use of the [
] in Steam Generator Applications Approved system codes, including S-RELAP5-based models, employ the [
] as part of the overall primary-to-secondary heat transfer formulation. It is well understood by code developers and users that the [
] was originally developed from idealized laboratory experiments involving single tubes and fully developed turbulent flow. It was not intended to directly represent the complex geometry and coupled phenomena present in a Pressurized Water Reactor (PWR) steam generator, including tube bundles, crossflow effects, U-bends, and spatially varying heat transfer mechanisms.
Accordingly, direct application of the textbook [
] without adjustment is not sufficient to represent actual plant behavior. For this reason, steam generator heat transfer is conditioned (calibrated) to plant data to ensure realistic steady-state conditions at the start of transient analyses. This practice is long-standing and essential for establishing representative initial conditions for safety analyses.
Through this conditioning process, the original laboratory basis of the [
] is effectively superseded. The resulting heat transfer model is no longer a generic textbook correlation, but a plant-specific adaptation of the [
]
tailored to the measured thermal performance of each nuclear power plant. In this context, the correlation functions as a calibrated component of an integrated plant model rather than as an independent empirical predictor.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-10 2.2.2.3 Applicability of Textbook and Experimental Uncertainty to Plant-Calibrated Models Because the [
] is adapted to each plant configuration, textbook uncertainties derived from laboratory experiments are not directly applicable to the plant-calibrated correlation. The variability reported in experimental studies reflects deviations between an idealized correlation and measurements obtained in non-prototypical geometries and flow configurations. That variability does not represent the uncertainty of a steam generator heat transfer model that has been conditioned to plant performance.
Applying large uncertainty distributions to the plant-calibrated correlation effectively offsets the conditioning performed to establish representative plant behavior at the start of the transient. Large perturbations to the heat transfer coefficient can decouple the model from the plant data used to define steady-state conditions, resulting in initial conditions and transient responses that are no longer representative of the actual plant configuration.
In this context, the application of large textbook-based uncertainties does not enhance conservatism or physical realism. Rather, it degrades model fidelity by introducing conditions that are inconsistent with the measured plant state and the intended use of the system model. Preserving plant representativeness is essential to meaningful safety analysis, and uncertainty treatment should not undermine that objective.
2.2.2.4 Applicability of the Expanded Database Assessment and Pressure Considerations The journal article cited by Framatome (Reference 3) was used to inform the order of magnitude of variability associated with the [
] under constrained conditions, not as a direct surrogate for PWR steam generator operating conditions.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-11 The NRC staff correctly noted that the database includes supercritical water and pressures that exceed typical PWR operating pressures. These observations confirm that the database is not prototypical of PWR steam generator local conditions.
For single-phase forced convection, pressure does not appear explicitly in the [
] and influences heat transfer only through its effect on thermophysical properties [
] Although supercritical conditions can produce strong property gradients and nonclassical heat-transfer behavior, PWR steam generators operate in a stable, subcooled single-phase regime where such effects do not occur.
In spite of these limitations, the [
] uncertainty reported in Reference 3 is similar to the observed spread of the data provided in Reference 2. The basis for the usage of the
[
] is described in later sections.
2.2.2.5 Horizontal Flow Considerations The NRC staff notes that the expanded database excluded data for flows other than vertical upward, whereas portions of the Byron and Braidwood SGs may include regions where local flow may be horizontal or otherwise not perfectly vertical over portions of the flow path, such as in the preheater region.
This observation further underscores the limited applicability of laboratory correlation assessments to detailed local steam generator conditions. Secondary-side nodalization in system thermal-hydraulic models is not intended to resolve tube-level orientation effects or local flow direction variations. Instead, the [
] is applied within a global, averaged modeling framework that represents the integrated heat transfer behavior of the steam generator as a whole.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-12 Accordingly, local regions of non-vertical or horizontal flow do not constitute independent uncertainty sources that can be meaningfully isolated or sampled using laboratory-based correlation variability. The integrated, plant-calibrated heat transfer model inherently accounts for the combined effects of geometry, orientation, and flow distribution at a system level, consistent with the intended scope and resolution of the analysis.
2.2.2.6 Basis for the [
]
The [
] should not be interpreted as a precise statistical descriptor derived from a single experimental database. Rather, it represents a conservative characterization of the variability associated with a plant-calibrated steam generator heat transfer model.
By contrast, the originally imposed [
] is not directly supported by the referenced literature and does not reflect how variability is characterized in sources such as Reference 2. The commonly cited [
]
represents an engineering accuracy or scatter band observed in laboratory-scale experiments conducted in idealized geometries; it is not defined as a statistical confidence interval and therefore assumptions would need to be made to infer a normal-distribution standard deviation.
In addition, the underlying experimental data reflect idealized laboratory configurations and do not represent the behavior of a plant-calibrated steam generator heat transfer model. They also do not account for conditioning (calibration) applied to establish representative plant conditions. Applying such large variability would substantially reduce the representativeness of the model without providing additional safety insight.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 2-13 Within this context, an [
] in conjunction with a [
] provides a conservative characterization of variability given the extent to which plant calibration reduces experimental uncertainty. The proposed sampling range is [
]
2.2.2.7 Conclusion In summary, the cited experimental databases are only approximately representative of PWR steam generator geometry, orientation, or operating conditions. Interpreting laboratory-scale scatter from these databases as probabilistic uncertainty leads to non-representative model behavior without improving safety insight.
NRC guidance in Standard Review Plan Section 15.0.2, while expressed as review and documentation criteria, reflects the expectation that safety analyses be based on a complete and accurate representation of plant initial and boundary conditions, and that uncertainty treatment be applied to parameters defining plant operating conditions.
Applying large textbook-based uncertainties to plant-calibrated steam generator heat transfer models degrades plant representativeness, introduces nonphysical behavior, and is inconsistent with the analytical intent of this guidance.
The [
] provides a conservative characterization of variability while preserving analytical fidelity and the ability of the evaluation model to represent plant behavior.
Framatome Inc.
ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 3-1 3.0 ARITA L&C 3 SUPPLEMENTAL INFORMATION 3.1
[
]
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 3-6 3.2
[
]
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 3-9 Figure 3-1
[
]
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[
]
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[
]
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[
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[
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[
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[
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[
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[
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[
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[
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ANP-4184 Revision 0 Byron and Braidwood LAR Inputs for Dittus-Boelter and Sampling Strategy Supplement 1NP Revision 0 Technical Report Page 3-20 Figure 3-12
[
]
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4.0 REFERENCES
- 1. Constellation, License Amendment Request for Proposed Change to Limitations and Conditions on Non-LOCA Transient/Accident Methodology, November 12, 2025 (ADAMS Accession No. ML25318B207).
- 2. McAdams WH (1942) Heat transmissions, 2nd edition. McGraw-Hill, New York.
- 3. Assessment of Convective Heat Transfer Correlations Against an Expanded Database for Different Fluids at Supercritical Pressures, Journal of Nuclear Engineering And Radiation Science, Volume 4, Issue 1, January 2018.
- 4. ANP-10339P-A, Revision 0, ARITA - ARTEMIS/RELAP Integrated Transient Analysis Methodology Topical Report, October 2023.
- 5. Constellation, License Amendment to Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, to transition to Framatome GAIA fuel and exemptions to 10 CFR 50.46 and 10 CFR 50 Appendix K, May 28, 2024 (ADAMS Accession No. ML24149A126).
- 6. Nuclear Regulatory Commission, Braidwood Station, Units 1 and 2; and Byron Station, Units, 1 and 2 - Issuance of Amendments to Revise Technical Specifications to use Framatome GAIA Fuel (EPID L-2024-LLA-0072), August 21, 2025 (ADAMS Accession No. ML25148A202).
- 7. EMF-2310(P)(A), Revision 1, SRP Chapter 15 Non-LOCA Methodology for Pressurized Water Reactors, May 2004.
Summary of Proposed Changes to LAR (Non-Proprietary)
1 of 2 Summary of Proposed Changes to LAR On November 12, 2025, Constellation Energy Generation, LLC (CEG) submitted a license amendment request (LAR) to update the limitations and conditions (L&C) #3 and #10 (ML25318B207) associated with NRC approved Non-LOCA Transient/Accident Methodology for Byron Station, Units 1 and 2 and Braidwood Station, Units 1 and 2. The proposed changes to update L&C #3 and #10 were:
L&C #3:
[
]
[
]
NOTE: Analyses which [
] using the previously approved methods remains valid. [
] the ARITA methodology.
L&C #10:
[
] in all applicable safety analyses. [
] in ARITA-based analyses [
] This proposed change applies to all transients evaluated using the ARITA methodology [
] including those supporting Departure from Nucleate Boiling (DNB), Fuel Centerline Melt (FCM), and Transient Cladding Strain (TCS) evaluations. [
]
(Non-Proprietary)
2 of 2 In the February 24, 2026 supplement, CEG requests changing the proposed methodology to modify L&C #10. It is proposed that L&C #10 the following method:
L&C #10:
[
] in all applicable safety analyses. The [
] within the ARITA methodology (i.e. all transients evaluated using the ARITA methodology that rely on this correlation) are proposed to be updated as follows:
[
]
The corresponding [
]
[
additional information is provided to support the original requested change.
(Non-Proprietary)
A F F I D A V I T
- 1.
My name is Morris Byram. I am Manager, Licensing & Regulatory Affairs for Framatome Inc. (Framatome) and as such I am authorized to execute this Affidavit.
- 2.
I am familiar with the criteria applied by Framatome to determine whether certain Framatome information is proprietary. I am familiar with the policies established by Framatome to ensure the proper application of these criteria.
- 3.
I am familiar with the Framatome information contained in Attachment 3 to CEG letter RS-26-015, with subject Supplement Related to License Amendment Request for Proposed Change to Limitations and Conditions on Non-LOCA Transient/Accident Methodology, and referred to herein as Document. Information contained in this Document has been classified by Framatome as proprietary in accordance with the policies established by Framatome for the control and protection of proprietary and confidential information.
- 4.
This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by Framatome and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.
- 5.
This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is requested qualifies under 10 CFR 2.390(a)(4) Trade secrets and commercial or financial information.
- 6.
The following criteria are customarily applied by Framatome to determine whether information should be classified as proprietary:
(a)
The information reveals details of Framatomes research and development plans and programs or their results.
(b)
Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.
(c)
The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for Framatome.
(d)
The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for Framatome in product optimization or marketability.
(e)
The information is vital to a competitive advantage held by Framatome, would be helpful to competitors to Framatome, and would likely cause substantial harm to the competitive position of Framatome.
The information in this Document is considered proprietary for the reasons set forth in paragraph 6(c), 6(d), and 6(e) above.
- 7.
In accordance with Framatomes policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside Framatome only as required and under suitable agreement providing for nondisclosure and limited use of the information.
- 8.
Framatome policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.
- 9.
The foregoing statements are true and correct to the best of my knowledge, information, and belief.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on: (2/20/2026)
(NAME) morris.byram@framatome.com 2101 Horn Rapids Road Richland, WA 99354 BYRAM Morris Digitally signed by BYRAM Morris Date: 2026.02.20 14:38:12 -08'00'