ML26029A402
| ML26029A402 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 01/28/2026 |
| From: | Ameren Missouri, Union Electric Co, Westinghouse |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML26029A397 | List: |
| References | |
| ULNRC-06922 | |
| Download: ML26029A402 (0) | |
Text
ULNRC-06922 Page 1 of 25 AXIOM, ADOPT', ZIRLO, Optimized ZIRLO', PRIME', and FULL SPECTRUM LOCA (FSLOCATM) are trademarks or registered trademarks of Westinghouse Electric Company LLC, its affiliates and/or its subsidiaries in the United States of America and may be registered in other countries throughout the world. All rights reserved.
Unauthorized use is strictly prohibited. Other names may be trademarks of their respective owners.
Limitations and Conditions Compliance for WCAP-18482-P-A, WCAP-18546-P-A, WCAP-16996-P-A, WCAP-18446-P-A, and WCAP-17642-P-A (Non-Proprietary)
ULNRC-06922 Page 2 of 25 1.0 Compliance with NRC SER Limitations and Conditions on the Use of ADOPT Fuel The NRC Staff reviewed Westinghouse topical report WCAP-18482-P-A, Westinghouse Advanced Doped Pellet Technology (ADOPT') Fuel, and concluded in a Staff Safety Evaluation Report (SER) that the generic topical report was acceptable for licensing applications, subject to the limitations and conditions (L&Cs) identified in the SER being addressed by the licensees. These limitations and conditions in the SER were considered in the safety analyses for Callaway. The application of ADOPT fuel for Callaway is compliant with the three general L&Cs (Methodology, Reactor and Cladding types, and Fuel Limitations) as addressed below. Note that the three general areas of the L&Cs have been broken into ten separate L&Cs.
1.1 WCAP-18482-P-A SER Limitation and Condition 1 Licensees must demonstrate that the CRE analytical models, methods, and acceptance criteria are applicable to fuel designs containing ADOPT fuel pellets and capture all relevant fuel burnup and cladding corrosion related phenomena.
Compliance:
Methodology from WCAP-15806-P-A (Reference 2) was used for the Callaway control rod ejection (CRE) analysis with ADOPT fuel. Regulatory Guide 1.236 (Reference 3) was followed for the generation of CRE acceptance criteria with regards to ADOPT fuel pellets relating to all fuel burnup and cladding corrosion related phenomena using ADOPT burnup dependent limit values from WCAP-18482-P-A (Reference 1).
1.2 WCAP-18482-P-A SER Limitation and Condition 2 ADOPT fuel must be used with the NRC-approved Westinghouse and CE PWR designs.
Compliance:
Callaway is licensed Westinghouse PWR design per References 4.
1.3 WCAP-18482-P-A SER Limitation and Condition 3 ADOPT fuel must be used with the NRC-approved Westinghouse and CE fuel designs with corresponding pellet and assembly dimensions.
Compliance:
ADOPT fuel will replace standard uranium dioxide (UO2) pellets used with the Westinghouse fuel design described in Enclosure 1. There are no changes to the corresponding pellet and assembly dimensions as compared to the existing licensed fuel design. The current 17x17 OFA fuel was licensed for Callaway in Reference 9.
ULNRC-06922 Page 3 of 25 1.4 WCAP-18482-P-A SER Limitation and Condition 4 ADOPT fuel shall be used with the NRC-approved zirconium based cladding materials, such as ZIRLO and Optimized ZIRLO'.
Compliance:
ADOPT fuel will be used with AXIOM cladding material, which is approved for licensing applications in WCAP-18546-P-A, Westinghouse AXIOM Cladding for Use in Pressurized Water Reactor Fuel. (Reference 6).
1.5 WCAP-18482-P-A SER Limitation and Condition 5 ADOPT fuel may be used with or without annular pellets and application of ZrB2 integral fuel burnable absorber (IFBA) coating but must be used consistent with the defined IFBA parameters in applicable NRC-approved fuel performance or product TRs.
Compliance:
ADOPT fuel will be used with annular blankets and the application of integral burnable absorber coating consistent with Reference 1.
1.6 WCAP-18482-P-A SER Limitation and Condition 6 Fuel burnup shall be limited to 62 GWd/MTU peak rod average for all cladding types.
Compliance:
Limitation and Condition 6 is modified with the implementation of WCAP-18446-P-A.
ADOPT fuel will operate within burnup levels approved in that topical report.
1.7 WCAP-18482-P-A SER Limitation and Condition 7 Nominal pellet density range will be [
]
Compliance:
The ADOPT pellet density requirement, [
]a,c, is specified on the Westinghouse pellet drawing and is consistent with Reference 1. The acceptance requirement, as identified in the ADOPT pellet specification for a pellet lot is 95%
confidence that 95% of lot is within the tolerance limit specified in the drawing.
ULNRC-06922 Page 4 of 25 1.8 WCAP-18482-P-A SER Limitation and Condition 8 Fuel grain size range will be [
] as measured according to ASTM E112 as linear intercept without correction factor, which corresponds to [
] with correction.
Compliance:
The ADOPT fuel grain size range requirement, [
]a,c, is identified is the Westinghouse ADOPT pellet specification and is consistent with Reference 1. The grain size is measured by the ASTM E112 (Reference 8) linear intercept method without correction factor, and the average grain size is used as a product acceptance criterion for all pellets.
1.9 WCAP-18482-P-A SER Limitation and Condition 9 Cr range from [
] which corresponds to inclusion of Cr2O3 ranging from
[
].
Compliance:
The chromium content requirement, [
]a,c, is identified in the Westinghouse ADOPT pellet specification and is consistent with Reference 1.
1.10 WCAP-18482-P-A SER Limitation and Condition 10 Al ranging from [
] which corresponds to inclusion of Al2O3 ranging from
[
].
Compliance:
The aluminum content requirement, [
]a,c, is identified in the Westinghouse ADOPT pellet specification and is consistent with Reference 1.
1.11 References 1.
WCAP-18482-P-A, Westinghouse Advanced Doped Pellet Technology (ADOPTTM) Fuel," September 2022.
2.
WCAP-15806-P-A, Westinghouse Control Rod Ejection Accident Analysis Methodology Using Multi-Dimensional Kinetics. November 2003.
3.
U.S. NRC Regulatory Guide 1.236, Pressurized-Water Reactor Control Rod Ejection And Boiling-Water Reactor Control Rod Drop Accidents.
4.
NUREG-2172, Safety Evaluation Report Related to the License Renewal of Callaway Plant, Unit 1, ML15068A342.
ULNRC-06922 Page 5 of 25 5.
WCAP-12488-A, Westinghouse Fuel Criteria Evaluation Process, October 1994.
6.
WCAP-18546-P-A, Westinghouse AXIOM Cladding for Use in Pressurized Water Reactor Fuel, March 2023.
7.
WCAP-17642-P-A, Revision 1, Westinghouse Performance Analysis and Design Model (PAD5), November 2017.
8.
ASTM E112, Standard Test Methods for Determining Average Grain Size.
9.
Letter from P. OConnor (NRC) to D. Schnell (UEC), Callaway Plant, Unit 1 -
Amendment No. 15 to Facility Operating License NPF-30, (ML021640733).
ULNRC-06922 Page 6 of 25 2.0 Compliance with NRC SER Limitations and Conditions on the Use of AXIOM Fuel Cladding The NRC Staff reviewed Westinghouse topical report WCAP-18546-P-A, Westinghouse AXIOM Cladding for Use in Pressurized Water Reactor Fuel. The Staff concluded in a safety evaluation report that the generic topical report was acceptable for licensing applications, subject to the ranges of fuel types, cladding, and reactors identified in the SER being addressed by the licensees. These ranges of fuel types, cladding, and reactors in the SER were considered in the safety analyses for Callaway. The application of AXIOM cladding for Callaway is compliant with the ranges of fuel types, cladding, and reactors, and therefore the limitations and conditions, from Reference 2, as addressed below.
2.1 WCAP-18546-P-A SER Limitation and Condition 1 AXIOM cladding must be used with the NRC-approved PWR designs.
Compliance:
Callaway is licensed Westinghouse PWR design per References 2.
2.2 WCAP-18546-P-A SER Limitation and Condition 2 AXIOM cladding must be used with the NRC-approved Westinghouse and CE fuel designs with corresponding pellet and assembly dimensions.
Compliance:
AXIOM cladding will replace ZIRLO in the 17x17 fuel assemblies currently used at Callaway (Reference 5).
2.3 WCAP-18546-P-A SER Limitation and Condition 3 AXIOM cladding must be used with the NRC-approved fuel materials and pellet coatings or additives (e.g., ADOPT, IFBA, gadolinium).
Compliance:
AXIOM cladding will be used with the NRC-approved ADOPT fuel pellets with IFBA coatings. ADOPT fuel additives and their use with IFBA coatings are approved for use in WCAP-18482-P-A (Reference 4).
2.4 WCAP-18546-P-A SER Limitation and Condition 4 Currently fuel burnup shall be limited to 62 GWd/MTU peak rod average for all cladding types, however, fuel rod burnup [
] may be allowed
ULNRC-06922 Page 7 of 25 once additional information specific to burnup to [
] is submitted and approved by the NRC.
Compliance:
Limitation and Condition 4 is modified with the implementation of WCAP-18446-P-A (Reference 3). AXIOM-clad fuel will operate within burnup levels approved in that topical report.
2.5 WCAP-18546-P-A SER Limitation and Condition 5 Best Estimate Oxide Thickness < 100 m.
Compliance:
The measured maximum oxide thickness of the AXIOM alloys are less than 50 m for a burnup of close to 75 GWd/MTU. The best estimate oxide thickness will be less than the allowed 100 µm for a peak rod average burnup as described in (Reference 4).
2.6 WCAP-18546-P-A SER Limitation and Condition 6 Best Estimate HPU [
]
Compliance:
The overall maximum hydrogen content for AXIOM cladding is ~ 200 ppm due to the combination of low maximum oxide thickness and low hydrogen pickup (HPU) ratio. The allowed best estimate HPU is [
]a,c.
2.7 References 1.
WCAP-18546-P-A, Westinghouse AXIOM Cladding for Use in Pressurized Water Reactor Fuel, March 2023.
2.
NUREG-2172, Safety Evaluation Report Related to the License Renewal of Callaway Plant, Unit 1, ML15068A342.
3.
WCAP-18446-P-A, Incremental Extension of Burnup Limit for Westinghouse and Combustion Engineering Fuel Designs, August 2024.
4.
WCAP-18482-P-A, Westinghouse Advanced Doped Pellet Technology (ADOPTTM) Fuel," September 2022.
5.
Letter from P. OConnor (NRC) to D. Schnell (UEC), Callaway Plant, Unit 1 -
Amendment No. 15 to Facility Operating License NPF-30, (ML021640733).
ULNRC-06922 Page 8 of 25 3.0 Compliance with NRC SER Limitations and Conditions on the Use of the FULL SPECTRUM' LOCA (FSLOCA') Evaluation Model (EM)
The NRC reviewed the FSLOCA EM and concluded in a Staff Safety Evaluation Report (SER),
Reference 1, that the generic topical report was acceptable for licensing applications, subject to the limitations and conditions identified in the SER being addressed by the licensees. A summary of each limitation and condition and how it was met is provided below.
3.1 WCAP-16996-P-A SER Limitation and Condition 1 The FSLOCA' EM applicability for performing PWR LOCA analyses is defined in terms of applicable accident transient phases so that the FSLOCA' EM cannot be applied for analyzing the long-term core cooling phase of LOCA transients for the purpose of demonstrating compliance with the long-term core cooling requirement set forth in 10 CFR 50.46(b)(5). This limitation specifically addresses the condition that the FSLOCA' EM does not treat boric acid precipitation and therefore lacks capabilities to address adequately post-LOCA long-term core cooling. The numerical approximations to advection and diffusion in the WCOBRA/TRAC-TF2 code conservation equations have neither been validated nor shown to successfully track the movement of high concentrations of boric acid between the vertical and radial cells with the vessel volumes.
Compliance:
The analyses for Callaway with the FSLOCA EM and the LOCA incremental burnup extension methodology are only being used to demonstrate compliance with the applicable ECCS acceptable criteria discussed in Section 3.8.4 of Enclosure 1 and are not being used to demonstrate compliance with 10 CFR 50.46 (b)(5).
3.2 WCAP-16996-P-A SER Limitation and Condition 2 The FSLOCA' EM applicability for performing PWR LOCA analyses is defined in terms of applicable types of PWR plants so that the EM can be applied for LOCA analyses of Westinghouse designed three-loop and fourloop PWR plants with cold side emergency core cooling injection, only. Plant-specific applications will generally be considered acceptable if they follow the requirements pertinent to FSLOCA described in WCAP-16996-P/WCAP-16996-NP, Rev. 1, (LTR-NRC-15-88, LTR-NRC-17-47, and LTRNRC-15-102, Rev. 2) and comply and meet the NRC limitations and conditions in this table (where the later document supersedes the earlier document when differences exist). Plant-specific licensing actions referencing FSLOCA analyses should include a statement summarizing the extent to which the FSLOCA methods and modeling were followed, and justification for any departures. Should NRC staff review determine that absolute adherence to the modeling guidelines is inappropriate for a specific plant, additional information may be requested using the RAI process.
ULNRC-06922 Page 9 of 25 Compliance:
Callaway is a Westinghouse-designed 4-loop PWR with cold-side injection, so it is within the NRC-approved methodology. The analysis for Callaway utilized the NRC-approved FSLOCA methodology, except for the changes which were previously transmitted to the NRC pursuant to 10 CFR 50.46 in References 2 through 7 and the changes for applications of AXIOM cladding and ADOPT fuel pellets, as described in Reference 8 and Reference 9, respectively. It is noted that the analysis was performed with an updated code version with the errors reported in References 2 through 7 corrected.
Note that, for the LOCA incremental burnup extension analysis, this Limitation and Condition is superseded by Limitation and Condition Number 6 for the incremental burnup extension methodology.
3.3 WCAP-16996-P-A SER Limitation and Condition 3 The coupled WCOBRA/TRAC-TF2 and COCO codes or standalone LOTIC2 code will be applied to calculate the containment backpressure in PWR LOCA analyses for Region II so that a conservatively low, although not explicitly bounded, containment pressure will be predicted and used. For this purpose, the input to the COCO model and its prediction results will be based on appropriate plant-specific containment design parameters and initial conditions and will simulate accordingly engineered safety features and installed systems capable of affecting the containment pressure including their actuation, performance, and associated processes. The following specific limitations will apply for Region II analyses using the FSLOCA' EM: (1) an acceptable plant-specific initial containment temperature will be determined based on input from the utility for the purpose of modeling the containment pressure response with COCO or LOTIC2; and (2) unqualified or indeterminate coatings throughout containment and qualified coatings within the break jet zone-of-influence will not be credited for the purpose of modeling the containment pressure response using COCO or LOTIC2 consistent with the bounding treatment of this parameter (conservatively low containment pressure). Please see LTR-NRC-15-102, Revision 2 (pages P-7 to P-10) for containment modeling.
Compliance:
The containment pressure calculations for the Callaway FSLOCA EM analysis and LOCA incremental burnup extension analysis use the COCO model and were performed consistent with the NRC-approved methodology. Appropriate design parameters and conditions were modeled, as were the engineered safety features which can reduce the containment pressure. A plant-specific initial temperature associated with normal full-power operating conditions was modeled, and no coatings were credited on any of the containment structures.
3.4 WCAP-16996-P-A SER Limitation and Condition 4 As implemented by Westinghouse and found acceptable from the review of the decay heat model in the FSLOCA' EM, the following conditions will apply with regard to decay heat
ULNRC-06922 Page 10 of 25 modeling and sampling in PWR LOCA analyses for Region I and Region II: (1) decay heat uncertainty will be [
] in uncertainty analyses for both Region I and Region II according to Table 29-4 in WCAP-16996-P/WCAP-16996-NP, Revision 1, Volume III, Section 29; (2) the FSLOCA' EM cannot be applied for transient time longer than 10,000 seconds following shutdown unless the decay heat model is shown to be acceptable for the analyzed core conditions. The latter limitation is [
] The sampled value of the decay heat uncertainty multiplier, DECAY_HT, reported in units of and absolute units, as applied for the limiting runs in Region I and Region II in the plant-specific analysis as part of a License Amendment Request submittal, will be provided as part of the submittal.
Compliance:
Consistent with the NRC-approved methodology, the decay heat uncertainty multiplier was
[
]a,c for the Callaway FSLOCA EM analysis and LOCA incremental burnup extension analysis. The analysis simulations were all executed for no longer than 10,000 seconds following reactor trip. The sampled values of the decay heat uncertainty multiplier for the cases which produced the Region I and Region II analysis results for the FSLOCA EM analysis have been provided in units of sigma and approximate absolute units in Table 1.
Table 1. Sampled Value of Decay Heat Uncertainty Multiplier, DECAY_HT, for Callaway FSLOCA EM Region I and Region II Analysis Cases Region Case DECAY_HT (units of )
DECAY_HT (absolute units)*
Region I PCT
+0.0895 0.49%
MEM
+0.8625 4.75%
CWO N/A**
N/A**
Region II (OPA)
+0.0680 0.35%
MEM
+0.7508 4.12%
CWO
+0.1008 0.52%
Region II (LOOP)
+0.0680 0.35%
MEM
+0.1955 1.08%
CWO
+0.1008 0.52%
- Approximate uncertainty in total decay heat power at 1 second after shutdown as defined by the ANSI/ANS-5.1-1979 decay heat standard for 235U, 239Pu, and 238U assuming infinite operation.
- No decay heat uncertainty value is provided for the Region I CWO case since the analysis result for all runs is 0.00%.
ULNRC-06922 Page 11 of 25 3.5 WCAP-16996-P-A SER Limitation and Condition 5 The maximum assembly average burnup will be limited to [
] and the maximum peak rod length-average burnup will be limited to [
] within the FSLOCA' EM. See WCAP-16996-P, Revision 1, Section 32.4, Methodology Limitations, page 32-21.
Compliance:
The maximum analyzed assembly and rod length-average burnup in the Callaway FSLOCA EM analysis were less than or equal to [
]a,c respectively, for assemblies in the core interior. However, the maximum analyzed assembly average burnup was greater than [
]a,c for assemblies in the core periphery.
Limitation and Condition Number 5 was revisited for the LOCA incremental burnup extension methodology, as described in Section 4.6 of Reference 10. As noted in Section 4.6.5 of Reference 10, the nuclear physics data within the WCOBRA/TRAC-TF2 code were updated as described in this section to extend the validity of the kinetics and decay heat model to an assembly and rod average burnup of [
]a,c. The Callaway FSLOCA EM analysis was performed with a code version that included the updated nuclear physics data, and the maximum analyzed assembly average burnup was less than [
]a,c for assemblies in the core periphery. Therefore, the exception to Limitation and Condition Number 5 is acceptable.
Note that, for the LOCA incremental burnup extension analysis, this Limitation and Condition is superseded by Limitation and Condition Numbers 4 and 8 for the incremental burnup extension methodology.
3.6 WCAP-16996-P-A SER Limitation and Condition 6 In the FSLOCA' EM applications for PWR LOCA analyses, the latest version of an NRC approved version of the latest fuel performance code that is applicable for the LOCA analysis will be used to initialize the fuel rod initial conditions. If the PAD 5.0 code is the latest approved version for fuel performance LOCA evaluations, then this version will be used to interface with WCOBRA/TRAC-TF2. The fuel performance code utilized shall be used to initialize WCOBRA/TRAC-TF2 using appropriate calculative methods to maximize the initial fuel stored energy and gap pin pressure, as well as adhere to any restrictions and limitations that resulted from the staff review and acceptance. The fuel performance code calculative methods should therefore exercise those modeling techniques approved by the staff for initializing WCOBRA/TRAC-TF2 for LOCA evaluations. The fuel performance code shall also include the effects of fuel thermal conductivity degradation and its attendant effects on fuel rod behavior for application to the WCOBRA/TRAC-TF2 code.
ULNRC-06922 Page 12 of 25 Compliance:
PAD5 fuel performance data were utilized in the Callaway analysis with the FSLOCA EM.
The analyzed fuel pellet average temperatures bound the maximum values calculated in accordance with Section 7.5.1 of Reference 11, and the analyzed rod internal pressures were calculated in accordance with Section 7.5.2 of Reference 11.
Note that, for the LOCA incremental burnup extension analysis, this Limitation and Condition is superseded by Limitation and Condition Numbers 4 and 7 for the incremental burnup extension methodology.
3.7 WCAP-16996-P-A SER Limitation and Condition 7 As implemented by Westinghouse and found appropriate based on the review of the two-phase interfacial drag model of the 3D VESSEL module in WCOBRA/TRAC-TF2 and its assessment, the interfacial drag multiplier, YDRAG, applied to the small bubble, small-to-large bubble, and churn-turbulent flow regimes of the Cold Wall two-phase flow map and to the Hot Wall two-phase flow map interfacial drag will be [
] established for YDRAG in the FSLOCA EM as described in WCAP-16996-P/WCAP-16996-NP, Revision 1, Section 13.4 and Section 29.1.5 as lower interfacial drag reduces the two-phase mixture thus promoting core uncovery. This [
] The comprehensive list of [
] is given in Table 29.2.3-1 of WCAP-16996-P, Revision 1 (see page 29-52).
Compliance:
Consistent with the NRC-approved methodology, the YDRAG uncertainty parameter was
[
]a,c for the Callaway Region I analysis with the FSLOCA EM.
Note that this Limitation and Condition is not applicable to the Callaway LOCA incremental burnup extension analysis [
]a,c 3.8 WCAP-16996-P-A SER Limitation and Condition 8 As implemented by Westinghouse and found acceptable from the review of the corresponding WCOBRA/TRAC-TF2 models, certain uncertainty contributors will be [
] for Region I analyses with the FSLOCA' EM according to Table 29.2.3-1 and Table 29-2 in WCAP-16996-P/WCAP-16996-NP, Revision 1, Volume III, Section 29.2.3. Specifically, the [
]
ULNRC-06922 Page 13 of 25
[
] as established in the FSLOCA' EM and described in WCAP-16996-P, Revision 1, Section 17.2.3 and Section 29.1.6 for KCOSI and in Section 4.4.5 and Section 29.1.7 for HS_SLUG. Lower condensation heat transfer in the cold legs may influence depressurization rate during an SBLOCA boil-off period. A higher transition boundary delays transition to non-stratified flow thus increasing residual liquid in the loop seal regions and decreasing vapor venting capacity. These [
] To summarize, [
] can be found in Tables 29-1, 29-2, 29-3a, 29-3b, 29-4, and 29-5 in WCAP-16996-P, Revision 1 (see pages 29-5 through 29-11). A compilation of the uncertainty parameter values and ranges can also be found in Table I of LTR-NRC-15-85.
Also note that with either of these above references, [
] as documented in LTR-NRC-15-102, Revision 2.
Compliance:
Consistent with the NRC-approved methodology, the [
]a,c for the Callaway Region I analysis with the FSLOCA EM.
Note that this Limitation and Condition is not applicable to the Callaway LOCA incremental burnup extension analysis [
]a,c 3.9 WCAP-16996-P-A SER Limitation and Condition 9 In PWR plant type-specific applications of the FSLOCA' EM for designs which are not Westinghouse 3-loop PWRs, a confirmatory evaluation will be performed for Region I analyses to assess the effect associated with the [
] This confirmatory evaluation will be performed once for each PWR plant type (e.g., Westinghouse design four-loop PWR plant) analyzed with the FSLOCA' EM and referenced in subsequent plant-specific FSLOCA' analyses of the same PWR plant type.
ULNRC-06922 Page 14 of 25 Compliance:
Callaway is a Westinghouse-designed 4-loop PWR. The requested sensitivity study was performed for a 4-loop Westinghouse-designed PWR and is discussed in Reference 12.
Note that this Limitation and Condition is not applicable to the Callaway LOCA incremental burnup extension analysis [
]a,c 3.10 WCAP-16996-P-A SER Limitation and Condition 10 In PWR plant type-specific application of the FSLOCA' EM for designs which are not Westinghouse 3-loop PWRs, a confirmatory evaluation will be performed to demonstrate that the applied break size boundary between Region I and Region II serves the intended goal of [
] As of part this evaluation, it will be demonstrated that no unexplained behavior in the predicted safety criteria, including PCT, occurs across the boundary between Region I and Region II. In addition, it will be confirmed that [
] In addition, it is important to also assure that the limiting small break between about 2-and 4-inch in an equivalent break diameter is properly captured by the robust Region I analysis approach. Plants with larger RCS fluid volumes than the Beaver Valley plant test example in WCAP-16996-P/WCAP-16996-NP, Revision 1, should cover the same 2-to 4-inch range using break area to RCS volume scaling to assure that the 2-to 4-inch break range is preserved and not artificially truncated. This confirmatory evaluation will be performed once for each PWR plant type (e.g., Westinghouse design four-loop PWR plant) analyzed with the FSLOCA' EM and referenced in subsequent plant-specific FSLOCA' analyses of the same PWR plant type. The WCOBRA/TRAC-TF2 code is applicable for analysis over the entire break spectrum of LOCA transients. However, for the purpose of the Region II analysis, the minimum of the break area sampling should extend only to 1.0 ft2 consistent with the ASTRUM LBLOCA EM (WCAP-16009-P-A, Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM), Revision 0) in lieu of the Region I/II boundary.
Compliance:
Callaway is a Westinghouse-designed 4-loop PWR. The requested sensitivity study was performed for a 4-loop Westinghouse-designed PWR and is discussed in Reference 12.
The minimum sampled break area for the Callaway Region II analyses with the FSLOCA EM and the LOCA incremental burnup extension methodology was 1 ft2.
ULNRC-06922 Page 15 of 25 3.11 WCAP-16996-P-A SER Limitation and Condition 11 For each analysis performed using the FULL SPECTRUMTM LOCA methodology, the [
] seed, analysis inputs, and [
] to be used for the Region I and Region II uncertainty analyses will be declared and documented prior to performing the uncertainty analyses.
The [
] will not be adjusted as a result of the outcome. Should a plant-specific application of the FSLOCA' EM deviate from the originally declared analysis inputs for the intended purpose of demonstrating compliance with the applicable acceptance criteria, all modification(s) will be discussed in a calculation file and in the ECCS analysis submittal to NRC, as applicable, to explain the applicable reasons for the modification(s). In this instance, the analysis inputs will be modified only for the purpose of reflecting the implemented and described modeling changes. In addition, the calculated preliminary values for PCT, MLO, and CWO for each such case will be summarized for information only in the ECCS analysis submittal to the NRC. Because these preliminary analyses and results are not intended to demonstrate compliance with the criteria of 10 CFR 50.46, formal Appendix B verification and archival documentation of the underlying analyses are not required. Furthermore, operating ranges used in a plant-specific analysis as part of the sampling uncertainty analysis for Regions I and II are to be supplied for review by the NRC in a table format for both regions. In plant-specific reviews, the uncertainty treatment for such plant operating parameters including the sampled distributions and ranges will be considered acceptable if they meet or exceed corresponding design basis and/or Technical Specification limiting conditions for operation limits, with uncertainties included, as appropriate.2 Alternative approaches may be used, provided they are supported with appropriate justification. [
] are given in Table 1 of LTR-NRC-17-47. Note that [
] as per limitation no. 15 below.
Note 2: This condition should not be construed to imply that exceeding limiting values by any amount is acceptable; sampling distributions for plant parameters should be realistic and justifiable.
Compliance:
This Limitation and Condition was met for the Callaway analyses with the FSLOCA EM and the LOCA incremental burnup extension methodology as follows:
1.
The [
]a,c the Region I and Region II analysis seeds, and the analysis inputs were declared and documented prior to performing the Region I and Region II uncertainty analyses with the FSLOCA EM.
The [
]a,c and the Region I and Region II analysis seeds were not changed once they were declared and documented.
The [
]a,c Region II analysis seed, and Region II analysis inputs were declared and documented prior to performing the Region II uncertainty analyses with the LOCA incremental burnup extension methodology. The [
]a,c and Region II analysis seed were not changed once they were declared and
ULNRC-06922 Page 16 of 25 documented. [
a,c 2.
The inputs for the Callaway analyses with the FSLOCA EM and the LOCA incremental burnup extension methodology were not changed once they were declared and documented.
3.
The plant operating ranges which were sampled within the uncertainty analyses with the FSLOCA EM and the LOCA incremental burnup extension methodology are provided for Callaway in Table 1 of Enclosure 1.
3.12 WCAP-16996-P-A SER Limitation and Condition 12 In plant-specific applications of the FSLOCA' EM, a check will be performed to confirm that effects associated with dynamic pressure losses from the steam generator secondary side to the main steam safety valves (MSSVs) are properly considered and adequately accounted for in the plant model used for the design-basis LOCA analyses consistent with NRC Information Notice 97-09, Inadequate Main Steam Safety Valve (MSSV) Set Points and Performance Issues Associated with Long MSSV Inlet Piping. SBLOCA performance is dependent on secondary pressure as it establishes primary pressure, and the consequential emergency core cooling system injection rate and potential for and degree of core uncovery.
Compliance:
A bounding plant-specific dynamic pressure loss from the SG secondary side to the main steam safety valves (MSSVs) was modeled in the Callaway analysis with the FSLOCA EM.
Note that this Limitation and Condition is not applicable to the Callaway LOCA incremental burnup extension analysis [
]a,c 3.13 WCAP-16996-P-A SER Limitation and Condition 13 In plant-specific applications of the FSLOCA' EM, [
] in the PWR model used to perform the design-basis LOCA transient calculations, to capture the proper core two-phase level response should the core uncover. Additionally, the [
] in such calculations. See Section 29.5.3, Venting, page 29-141 of WCAP-16996-P, Revision 1.
]
ULNRC-06922 Page 17 of 25 Compliance:
The [
]a,c in the analyses for Callaway with the FSLOCA EM and the LOCA incremental burnup extension methodology. The [
]a,c in these analyses.
3.14 WCAP-16996-P-A SER Limitation and Condition 14 For demonstration of compliance with the current 10 CFR 50.46 oxidation criterion, the oxidation result using Baker-Just to convert the LOCA transient time-at-temperature to an equivalent cladding reacted shall be compared against the 17 percent limit. If Cathcart-Pawel is used to convert the LOCA transient time-at-temperature to an equivalent cladding reacted, the oxidation result shall be compared to a 13 percent limit with the pre-transient oxide layer thickness being included in the prediction results. Should this measure (Cathcart-Pawel) 13 percent limitation) not be carried forth to other NRC approvals of new realistic applications or should the value be changed, this SE and the two associated restrictions will be subsequently revised. See memorandum Ashok Thadani, Director, RES to Samual J. Collins, Director, NRR,Research Information Letter 0202, Revision of 10 CFR 50.46 and Appendix K, dated June 20, 2002, Appendix 2, page 9.
Compliance:
The maximum local oxidation (MLO) criterion of 17% is replaced with the NRC-approved AXIOM cladding performance-based embrittlement criterion. The Cathcart-Pawel ECR is confirmed to remain below the DBT limit for AXIOM cladding described in Section 3.11 of Reference 8. Limitation and Condition Number 14 is therefore not applicable to the Callaway FSLOCA EM analysis.
Note that this Limitation and Condition is not applicable to the Callaway LOCA incremental burnup extension analysis since [
]a,c 3.15 WCAP-16996-P-A SER Limitation and Condition 15 Identification of the offsite power availability limiting condition for the Region II FSLOCA' evaluation is required by GDC 35. In lieu of the method proposed by Westinghouse for addressing this requirement described in LTR-NRC-15-102, Revision 2, page 25, plant-specific applications of the FSLOCA' EM should include two complete sets of sampled statistical evaluations; (1) a complete set with offsite power available and (2) a second complete sampling set without offsite power available. For each set, the calculated statistical results at the 95/95 probability, confidence level should be demonstrated to comply with regulatory limits for PCT, MLO, and CWO. The [
] to provide the required 95/95 probability, confidence statement that addresses the three major criteria of PCT, MLO, and CWO. This condition should be consistent with limitation number 11 in the table for [
] for each sample set.
ULNRC-06922 Page 18 of 25 Compliance:
The Region II uncertainty analyses for Callaway with the FSLOCA EM and the LOCA incremental burnup extension methodology were performed twice; once assuming a LOOP and once assuming OPA. The results from both analyses that were performed are in compliance with the applicable ECCS acceptance criteria (see Section 3.8.4 of Enclosure 1).
The [
]a,c 3.16 References 1.
Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology), WCAP-16996-P-A, Revision 1, November 2016.
2.
U.S. Nuclear Regulatory Commission 10 CFR 50.46 Annual Notification and Reporting for 2017, LTR-NRC-18-30, Revision 0, July 2018.
3.
U.S. Nuclear Regulatory Commission 10 CFR 50.46 Annual Notification and Reporting for 2018, LTR-NRC-19-6, Revision 0, February 2019.
4.
U.S. Nuclear Regulatory Commission 10 CFR 50.46 Annual Notification and Reporting for 2020, LTR-NRC-21-5, Revision 0, March 2021.
5.
U.S. Nuclear Regulatory Commission 10 CFR 50.46 Annual Notification and Reporting for 2021, LTR-NRC-22-8, Revision 0, February 2022.
6.
U.S. Nuclear Regulatory Commission 10 CFR 50.46 Annual Notification and Reporting for 2022, LTR-NRC-23-5, Revision 0, March 2023.
7.
U.S. Nuclear Regulatory Commission 10 CFR 50.46 Annual Notification and Reporting for 2023, LTR-NRC-24-6, Revision 0, March 2024.
8.
Westinghouse AXIOM Cladding for Use in Pressurized Water Reactor Fuel, WCAP-18546-P-A, Revision 0, March 2023.
9.
Westinghouse Advanced Doped Pellet Technology (ADOPT') Fuel, WCAP-18482-P-A, Revision 0, September 2022.
10.
Incremental Extension of Burnup Limit for Westinghouse and Combustion Engineering Fuel Designs, WCAP-18446-P-A, Revision 0, August 2024.
11.
Westinghouse Performance Analysis and Design Model (PAD5), WCAP-17642-P-A, Revision 1, November 2017.
ULNRC-06922 Page 19 of 25 12.
Information to Satisfy the FULL SPECTRUM LOCA (FSLOCA) Evaluation Methodology Plant Type Limitations and Conditions for 4-loop Westinghouse Pressurized Water Reactors (PWRs) (Proprietary/Non-Proprietary), LTR-NRC 50, Revision 0, July 2018.
ULNRC-06922 Page 20 of 25 4.0 Compliance with NRC SER Limitation and Conditions on the Use of Incremental Burnup Methodology The NRC reviewed the Incremental Burnup methodology and concluded in a Staff Safety Evaluation Report (SER) that the generic topical report was acceptable for licensing applications, subject to the limitations and conditions identified in the SER being addressed by the licensees. A summary of each limitation and condition and how it was met is provided below.
4.1 WCAP-18446-P-A SER Limitation and Condition 1 The applicability of this TR is limited to all currently manufactured Westinghouse and CE fuel designs. The specific list of applicable designs is provided in Section 7.1.1 of WCAP-18446-P/WCAP-18446-NP, Revision 0, TR. The fuel assembly mechanical design evaluation in Section 2.0 of the TR provides generic approval of the 17x17 OFA design for use at a fuel rod-average burnup of [
] A fuel assembly mechanical design evaluation, consistent with Section 2.0 of the TR, is needed to apply the incremental burnup extension to the fuel assemblies other than the 17x17 OFA design described in Section 7.1.1 of the TR. The additional evaluations may be included as part of a plant-specific application, a supplement to WCAP-18446-P/WCAP-18446-NP, Revision 0, or a separate TR.
Compliance:
The incremental burnup extension analysis for Callaway is for the 17x17 OFA fuel design.
4.2 WCAP-18446-P-A SER Limitation and Condition 2 The applicability of this TR is limited to UO2 or ADOPT fuel with ZIRLO, Optimized ZIRLO, or AXIOM cladding.
Compliance:
The incremental burnup extension analysis for Callaway is for both UO2 and ADOPT fuel pellets with AXIOM cladding. Only assemblies with AXIOM cladding will operate at rod-average burnups above 62 GWd/MTU in accordance with WCAP-18446-P-A.
4.3 WCAP-18446-P-A SER Limitation and Condition 3 The applicability of this TR is limited to un-poisoned fuel, fuel with integral fuel burnable absorber (IFBA), and fuel with gadolinia. This limitation does not preclude the use of wet annular burnable absorber (WABA) or other discrete burnable absorbers during the lifetime of an assembly.
Compliance:
The incremental burnup extension analysis for Callaway is for un-poisoned fuel, fuel with integral fuel burnable absorber (IFBA), and fuel with gadolinia.
ULNRC-06922 Page 21 of 25 4.4 WCAP-18446-P-A SER Limitation and Condition 4 The maximum fuel rod-average burnup and fuel assembly average burnup permitted with this TR is [
] While this TR does not constitute generic approval of the PAD5 methodology for rod-average burnups of [
] PAD5 is approved for the requested rod-average burnup of [
] when implemented within the WCAP-18446-P/WCAP-18446-NP methodology.
Compliance:
PAD5 fuel performance data was utilized in the incremental burnup extension analysis for Callaway for peripheral assemblies with a maximum rod and assembly average burnup of
[
]a,c.
4.5 WCAP-18446-P-A SER Limitation and Condition 5 A maximum of 5 weight percent fuel enrichment is permitted with this TR.
Compliance:
The incremental burnup extension analysis for Callaway is limited to a maximum of 5 weight percent fuel enrichment.
4.6 WCAP-18446-P-A SER Limitation and Condition 6 The WCAP-18446-P/WCAP-18446-NP, Revision 0, methodology for LOCA rupture calculations may only be applied to the Westinghouse 2-loop PWR and CE PWR designs after (1) the FSLOCA EM is approved for these designs and (2) the WCAP-18446-P/WCAP-18446-NP methodology is confirmed to be applicable for these designs.
Furthermore, the LOCA cladding rupture calculations for these designs [
] for 3-loop and 4-loop PWRs.
Compliance:
Callaway is a Westinghouse 4-loop PWR. As such, this Limitation and Condition is not applicable.
4.7 WCAP-18446-P-A SER Limitation and Condition 7 The NRC staff's approval of the WCAP-18446-P/WCAP-18446-NP, Revision 0, methodology is based on the incorporation of PAD5 fuel performance models and methods into the plant licensing basis for all fuel and safety analyses. Use of alternative methods to support any fuel or safety analysis will require acceptable plant-specific justification during the implementation review.
ULNRC-06922 Page 22 of 25 Compliance:
PAD5 fuel performance models and methods are being incorporated in the Callaway licensing basis via this plant-specific application to demonstrate compliance with the applicable 10 CFR 50.46 acceptance criteria.
4.8 WCAP-18446-P-A SER Limitation and Condition 8 Only rods in peripheral assemblies (i.e., assemblies with at least one face towards the core baffles) may exceed a rod-average burnup of 62 GWd/MTU. Fuel rods in assemblies with a half-face towards the baffles in CE-designed PWRs are limited to a maximum rod-average burnup of 62 GWD/MTU (similar to core interior assemblies).
Compliance:
The rod-average burnup is limited to 62 GWd/MTU in the non-peripheral assemblies as described in Enclosure 1. The incremental burnup extension analyses for Callaway demonstrates that there is a high level of probability that cladding rupture would not occur during a postulated LOCA for any rods in peripheral assemblies (i.e., assemblies with at least one face towards the core baffles) which exceed a rod-average burnup of 62 GWd/MTU. Note that this only applies to the new PRIME/ADOPT/AXIOM fuel. The legacy VANTAGE+ fuel will retain the 62 GWd/MTU burnup limit at all core locations.
4.9 WCAP-18446-P-A SER Limitation and Condition 9 Compliance:
In October 2023, the NRC released Revision 1 to RG 1.183. In Revision 1, the top of page 9 highlights this version as the current regulatory position regarding fuel burnup. More specifically this version applies to reactor core burnups up to a maximum rod-average of 68 gigawatt-days per metric ton uranium (GWd/MTU) for LOCA and non-LOCA models.
As a part of implementing the incremental increase in burnup described in WCAP-18446, Callaway proposes to increase the fuel burnup value to a maximum fuel rod-average burnup that conforms to the guidance in Revision 1 of RG 1.183. As described in Section 3.13 of Enclosure 1 and in Enclosure 8, Callaway has performed new dose analyses consistent with Revision 1 of RG 1.183 for the LOCA and fuel handling accident events.
With respect to qualification of equipment against the effects of radiological doses, Callaway will retain its current license basis as described in Section 3.13.3 of Enclosure 1.
4.10 WCAP-18446-P-A SER Limitation and Condition 10 Based on the data provided in Figure 2.5-5b of WCAP-18446-P/WCAP-18446-NP, Revision 0, this SE was unable to confirm acceptable performance of ZIRLO cladding with
[
]
ULNRC-06922 Page 23 of 25 respect to the [
] best-estimate hydrogen content pickup design limit or the predictive capability of the PAD5 hydrogen concentration model for ZIRLO cladding.
Additional justification should be provided on an application-specific basis demonstrating (1) that ZIRLO cladding will [
] is acceptable for rod-average burnups greater than 62 GWd/MTU (Section 3.1.4.5), and (2) the PAD5 hydrogen concentration model can acceptably predict the hydrogen content of ZIRLO cladding for rod-average burnups greater than 62 GWd/MTU.
Compliance:
Callaway is transitioning to AXIOM cladding in this request, and only assemblies with AXIOM cladding will operate at rod-average burnups above 62 GWd/MTU in accordance with WCAP-18446-P-A. As such, this Limitation and Condition is not applicable.
4.11 WCAP-18446-P-A SER Limitation and Condition 11 This SE has neither evaluated nor approved WCAP-18446-P/WCAP-18446-NP, Revision 0, as a method for determining compliance with the acceptance criteria in proposed rule 10 CFR 50.46c.
Compliance:
Callaway understands that the WCAP-18446-P-A SE neither evaluates nor approves the WCAP for determining compliance with the acceptance criteria in proposed rule 10 CFR 50.46c.
4.12 WCAP-18446-P-A SER Limitation and Condition 12 Each licensee implementing the WCAP-18446-P/WCAP-18446-NP, Revision 0, methodology shall describe and justify its proposed approach for implementing burnup dependence for rods that exceed 62 GWd/MTU into the core operating limit or another acceptable alternative.
Compliance:
Callaway is using the LCO and Tech Spec Bases approach described and justified in Section I of WCAP-18446-P-A and as accepted in the WCAP-18446-P-A SER.
4.13 WCAP-18446-P-A SER Limitation and Condition 13 When applying WCAP-10325-P-A as part of the methodology described in WCAP-18446-P/WCAP-18446-NP, Westinghouse must either (1) adequately justify the decay heat model in WCAP-10325-P-A is applicable up to the requested rod-average burnup extension limit (e.g., demonstrate the model is conservative with respect to decay heat curves generated from more detailed methods), either through a plant specific implementation submittal or through a supplement to this TR, or (2) adjust the inputs of the decay heat model in WCAP-10325-P-A to assume a full-power operation time and use a neutron capture factor appropriate for the extended cycle length of the nuclear design.
ULNRC-06922 Page 24 of 25 Compliance:
Core decay heat calculations were performed using ORIGEN-ARP. The results of these calculations demonstrate that the decay heat model used in WCAP-10325-P-A (Proprietary) and WCAP-10326-A (Non-proprietary) is applicable for initial fuel assembly enrichments and end-of-cycle (EOC) burnups that would be used in reload cycle design that implement the peak rod burnup limit of WCAP-18446-P-A. The continued applicability would be confirmed with each reload.
4.14 WCAP-18446-P-A SER Limitation and Condition 14 When applying WCAP-17721-P-A as part of the methodology described in WCAP-18446-P/WCAP-18446-NP, Westinghouse must either (1) adequately justify that equation 11 in the ANSI/ANS 5.1-1979 decay heat standard for determining the effects neutron capture of neutron capture is adequate for operating times beyond 4 years or (2) adjust the neutron capture model to provide appropriate predictions for operating times beyond 4 years.
Compliance:
Callaway is not applying WCAP-17721-P-A in this request. As such, this Limitation and Compliance is not applicable.
ULNRC-06922 Page 25 of 25 5.0 Compliance with NRC SER Limitation and Conditions on the Use of PAD5 Methodology The NRC reviewed the Incremental Burnup methodology and concluded in a Staff Safety Evaluation Report (SER) that the generic topical report was acceptable for licensing applications, subject to the limitations and conditions identified in the SER. Many of the limitations and conditions outlined in the SER summarize changes to the topical report content throughout the course of the review and describe actions for Westinghouse to maintain the topical report. As such, most of the limitation and condition compliance is not applicable to implementation at Callaway and will not be discussed.
Limitation and condition a) of the SER lists the cladding, fuel, burnable poison, and reactor types approved for use with the PAD5 methodology. This is the only limitation and condition that is appropriate for a compliance discussion for implementation at Callaway.
Since the approval of PAD5, many follow-on Westinghouse fuel topical reports have adjusted the models and methods of PAD5 for their specific application. Namely, the ADOPT fuel, AXIOM cladding, and Incremental Burnup methodologies each have made changes to the models and methods initially approved in PAD5.
The relevant information for compliance with the NRCs SER limitation and condition a) and b), as modified, is as follows:
Callaway will use the PAD5 methodology for Fuel Rod Design analyses for ADOPT fuel, AXIOM cladding, and PRIME assembly skeleton features as reviewed in their associated licensing activities.
Callaway will use the PAD5 methodology to analyze the fuel products described in at current enrichment limits and to the burnup limit described in the Incremental Burnup Methodology discussed in Section 4.0 of this enclosure.
Callaway will use the PAD5 methodology to analyze ADOPT and UO2 pellet to enrichments, ZrB2 and gadolinia burnable absorber enrichments, grain size, and densities described in the PAD5 SER and as amended by each products associated licensing activities.
Callaway will use the PAD5 methodology to analyze the fuel products described in to ensure that the fuel is operated at the steady-state rod average linear heat generations and local powers as described in the SER, and to ensure compliance with Callaways fuel centerline melt Safety Limits as proposed by this LAR.
The application of PAD5 at Callaway at no time exceeds the fuel melting temperature (calculated by PAD5) due to the lack of properties for molten fuel in PAD5 and other properties such as thermal conductivity and FGR.