ML24225A250
| ML24225A250 | |
| Person / Time | |
|---|---|
| Site: | PROJ0728, 99902041 |
| Issue date: | 08/21/2024 |
| From: | Licensing Processes Branch |
| To: | |
| References | |
| EPID L-2022-TOP-0038 ANP-10350P, Rev. 0 | |
| Download: ML24225A250 (1) | |
Text
OFFICIAL USE ONLY - PROPRIETARY INFORMATION Enclosure OFFICIAL USE ONLY - PROPRIETARY INFORMATION REGULATORY AUDIT REPORT FOR SUPPLEMENT TO FRAMATOME TOPICAL REPORT ANP-10350P, REVISION 0, FRAMATOME METHODOLOGY FOR BOILING WATER REACTORS: EVALUATION AND VALIDATION OF APOLLO2-A/ARTEMIS-B DOCKET NO. 99902041; EPID: L-2022-TOP-0038
1.0 BACKGROUND
By audit plan dated May 20, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24135A171), the U.S. Nuclear Regulatory Commission (NRC) staff conducted an audit for understanding of supplemental information submitted to the NRC by letter dated February 21, 2024 (ADAMS Package Accession No. ML24057A358) related to Framatome Topical Report (TR) ANP-10350P, Revision 0, Framatome Methodology for Boiling Water Reactors: Evaluation and Validation of APOLLO2-A/ARTEMIS-B. ANP-10350P, Revision 0 was submitted to the NRC for review by letter dated June 30, 2022 (ADAMS Package Accession No. ML22186A071). The supplemental information provides support and justification to extend the range of applicability of ANP-10350P, Revision 0 to include increased enrichment (IE) and higher burnup (HBU) conditions. The audit was virtually held on May 28 through May 30, 2024.
The NRC staff performed an audit for understanding to support timely completion of a safety evaluation (SE) in accordance with Office of Nuclear Reactor Regulation Office Instructions LIC-111, Regulatory Audits, and LIC-500, Topical Report Review Process.
2.0 REGULATORY AUDIT OBJECTIVES The objective of the audit was to increase review process efficiency through interaction with the Framatomes technical experts. During the audit, the NRC staff reviewed pertinent documentation made available by Framatome. A more detailed narrative on the topics covered is included below in Section 4.0, Discussion, of this audit report. A list of all the documents that the NRC staff reviewed is included in Section 5.0, Documents Reviewed.
The NRC audit team was composed of the following members:
Ashley Smith, Technical Reviewer (NRR/DSS/SFNB)
Alex Collier, Technical Reviewer (NRR/DSS/SFNB)
Jack Vande Polder, Technical Reviewer (NRR/DSS/SFNB)
Kevin Heller, Technical Reviewer (NRR/DSS/SFNB)
Ngola Otto, Project Manager (NRR/DORL/LLPB)
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION The following personnel represented or supported Framatome during the audit:
Alan Meginnis Jaron Senecal Alex Bennett Paul Smith Marty Bickford Dan Tinkler Michael Anderson 3.0 REGULATORY AUDIT BASES Framatome states in Section 1.3, Regulatory Requirements, of ANP-10350P that there are no regulatory requirements for a generic application of a core simulator. While there are no directly applicable requirements, a core simulator must adequately model core designs with an acceptable amount of uncertainty, as the core design establishes a basis for downstream safety analyses, which are used to demonstrate compliance with General Design Criteria 10, 11, 12, 13, 20, 25, 26, 27, and 28, as discussed in Section 4.3, Nuclear Design, of NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants.
4.0 DISCUSSION The audit began with a detailed overview of the supplement and current condition reports. In the audit plan, the NRC listed several topics that needed clarification or discussion. Most of these topics were directly linked to potential request for additional information (RAI) questions. The major discussion topics are described below.
4.1 RODEX4 Appendix A of ANP-10350P states that the APOLLO2-A/ARTEMIS-B fuel rod module (FRM) does not require additional verification for IE and HBU and will be maintained to be consistent with RODEX4. A proposed limitation and condition in Section 14.2, Limitations and Conditions, states that the FRM is subject to the relevant limitations and conditions in the current RODEX4 (TR and associated NRC SE) until it is superseded by the updated RODEX4 TR and staff SE.
Framatome confirmed in the audit that APOLLO2-A/ARTEMIS-B will not be applicable to HBU until RODEX4 is approved for HBU. The NRC staff intends to adjust the limitation and condition in the final ANP-10350P SE to clarify that ARTEMIS-B cannot be used for HBU until RODEX4 is approved for HBU and the ARTEMIS-B FRM has been verified in accordance with the limitations and conditions implemented in the updated RODEX4 SE.
Any Framatome advanced fuel management (AFM) updates to RODEX4 will be implemented into the ARTEMIS-B FRM, which may include gap conductance tables, porosity tables, radial power profiles, and thermal conductivity tables. The new FRM tables will be evaluated on a core follow benchmark in terms of sensitivity to uranium enrichment and assembly configuration. For AFM, only uranium enrichment sensitivities will be evaluated. Framatome representatives explained that the process for verifying the FRM will involve the AFM enrichment sensitivities being evaluated against set acceptance criteria, and new FRM tables will be generated and used if the acceptance criteria are not met. The NRC staff determined that an RAI was necessary to understand how the FRM will be verified and how the sensitivities will be evaluated.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION To support that the results were driven by geometry and not enrichment, Framatome discussed that the design differences between assembliesthe number of rods, part length rods, variations between water rods, crosses, and channels, and differences in configurationdo not significantly affect the error spreads. The NRC staff inquired about ((
)).
Additionally, other approaches to code qualifications, such as gamma scans, show that errors are not as dependent on lattice geometry as they are on other parameters such as fuel additives and pin locations. The NRC staff determined that an RAI was necessary to justify the application of ATRIUM 11 results to other fuel designs.
In Section A.1.4, Plant Lattice Type Results ((
)) AFM lattices were designed as both C and D lattice types, but the ((
)) AFM lattices were designed as D lattice types, and then had their water gaps adjusted to create a corresponding C lattice type. All the non-AFM ATRIUM 11 lattices were C lattice types. Framatome discussed that the design near the water gap varies little between the lattice types, and that most of the enrichment variation is near the edges. The intention of adjusting the ((
)) AFM D lattice types in C lattice types was not to create a realistic lattice, but to verify that the difference between the water gaps yielded similar uncertainties.
The NRC staff asked a few clarification questions regarding core design and the range of parameters used in the analyses. A plot in Section A.2.1, Figure A-57, indicated ((
)). Framatome representatives explained the figure plotted maximum gadolinium concentrations, and they provided a plot of the gadolinium concentrations used for all colorset geometries analyzed. Framatome representatives also ((
)). Framatome representatives explained the number of colorsets used for the pin power verification analyses by discussing how they were designed to be representative of actual lattice designs, covering the maximum possible uranium enrichment and gadolinium concentration. Plots of gadolinium concentrations and pin enrichments vs. AFM colorset geometry were provided.
4.3 NEUTRONICS Appendix A states that additional verification of reflector cross sections for AFM conditions is not needed because ((
)).
Framatome performed a sensitivity study with AFM fuel lattices. The NRC staff developed an RAI to provide justification that ((
)).
Data from ORNL/TM-2020/1833, Isotropic and Fuel Lattice Parameter Trends in Extended Enrichment and Higher Burnup Light Water Reactor Fuel, indicates that radial power pellet profiles would change due to IE. The radial power pellet profiles are calculated in both the FRM and APOLLO2-A. Framatome provided plots of the power profiles for AFM conditions and compared the results to the POLARIS calculations found in ORNL/TM-2020/1833. The NRC staff reviewed the results and explanations for the trends present in the APOLLO2-A results. An RAI was developed to request justification that APOLLO2-A accurately predicts radial power pellet profiles at IE and HBU.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION In Section 12, Gamma Scan Results, and RAIs 8 and 9 of ANP-10350P, the gamma scans for ATRIUM 10, Westinghouse OPTIMA 2, and MOX fuels are justified as being applicable to ATRIUM 11 at non-AFM conditions. Because Framatome does not have access to gamma scan data for AFM conditions, the NRC staff developed an RAI to request justification for the usage of previous gamma scans for IE and HBU.
Section A.2 covers pin power verification. Framatome did not perform analyses for coolant void comparisons, fuel temperature comparisons, or moderator void comparisons for AFM lattice designs. To verify that AFM lattice designs would not affect uncertainties for coolant void, fuel temperature, or moderator void, Framatome performed sensitivity studies for coolant void variation, fuel temperature, and moderator void with AFM lattice designs. The sensitivity studies were performed under the same conditions as their non-AFM counterparts (Sections 8.4, 8.5, and 8.6 of ANP-10350P, for coolant void, fuel temperature, and moderator void, respectively).
The sensitivity study found that ((
)). The NRC staff developed an RAI to confirm that APOLLO2-A can accurately predict pin powers at AFM conditions.
The ability of APOLLO2-A/ARTEMIS-B to resolve steep power gradients that may be present due to AFM assemblies being placed next to non-AFM assemblies was discussed. Framatome representatives described the spectral history models and discontinuity factors and explained that power gradients due to core design were unlikely because core loading is designed to be as flat as possible to maximize fuel utilization and margin to thermal limits. Additionally, current low leakage core designs have steep gradients between outside rows, and gradients have grown with power uprates and extended cycles without radial peaking uncertainties being negatively affected.
Experimental data up to the requested burnup limit was not provided. Framatome representatives explained that the data was not needed to verify accurate code predictions for higher burnup by providing numerical comparisons and showing that error trends ((
)).
The NRC staff inquired about ((
))
Spent fuel validation for higher enriched fuels and higher burnups was not included in the supplement. In the audit, Framatome provided comparisons between APOLLO2-A and SERPENT for uranium, plutonium, and gadolinium isotope concentrations as a function of burnup. An RAI was developed to justify that APOLLO2-A was accurately tracking isotope concentrations for higher enriched fuels and at higher burnup.
Section 6.2.4, Discussion, of ANP-10350P discusses the results of a spent fuel validation sensitivity study that was performed for a PWR core simulator. Framatome discussed the basis for the results of the study and the justification for the applying the studys results to BWR fuels.
Additionally, Framatome representatives discussed the effects of IE and HBU on spent fuel isotopic concentrations and uncertainties.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION 4.4 MISCELLANEOUS ANP-10350P used SERPENT for all its numerical verification analyses. The supplement also used SERPENT, with the exception of the critical experiments, which used MCNP. Framatome explained that the critical benchmark validation was performed independently of ARTEMIS-B development to support IE and HBU for the PWR version of ARTEMIS. For ARTEMIS-B, SERPENT was used for numerical validation for its optimization and depletion capabilities.
Framatome provided the NRC staff with references regarding SERPENTs V&V at extended burnup.
Section 4.5.4, Flow Area Changes, of ANP-10350P includes equations regarding two-phase pressure drop. The NRC staff inquired on the basis for the equations and Framatome provided the reference.
5.0 DOCUMENTS REVIEWED The following documents provided by Framatome were reviewed by the NRC staff during the audit:
FS1-0047044, Revision 1.0, Analysis of 9.83 wt% U235 Experiment (LEU-COMP-THERM-024) with APOLLO2-A, dated January 24, 2020 FS1-0048254, Revision 1.0, Analysis of 6.90 wt% U235 Experiment (LEU-COMP-THERM-078) with APOLLO2-A, dated February 21, 2020 FS1-0048714, Revision 1.0, Analysis of 6.90 wt% U235 Experiment (LEU-COMP-THERM-080) with APOLLO2-A, dated October 13, 2020 FS1-0048735, Revision 1.0, Analysis of 6.90 wt% U235 Experiment (LEU-COMP-THERM-097) with APOLLO2-A, dated September 28, 2020 FS1-0053110, Revision 1.0, Neutronics Input to Increased Enrichment Topical Report dated January 25, 2021 FS1-0069552, Revision 2.0, ARTEMIS-B APOLLO2-A BWR Colorset DHO Benchmark Validation for AFM Fuel, dated February 8, 2024 FS1-0070726, Revision 1.0, Comparisons of APOLLO2-A and SERPENT Depletions on AFM BWR Lattices, dated February 6, 2024 FS1-0070755, Revision 1.0, Validation of AFM APOLLO2-A BWR Lattice Calculations Against SERPENT Using a Maximum of 8wt% U-235, dated February 5, 2024 Plots of spent fuel isotopics pertinent to NRC audit questions on spent fuel validation and uncertainty quantification. Filename q17_concn_and_error.pdf
6.0 CONCLUSION
The audit accomplished the objectives listed in Section 2.0 by allowing direct interaction with Framatomes technical experts. The NRC staff participants were able to obtain clarification on multiple questions and examine calculation notes and supporting documentation. The NRC staff will continue its review of the supplement and have subsequently issued RAIs (ADAMS Package Accession No. ML24226B222) to address the issues where further information is necessary to complete the safety review.