ML25035A079
| ML25035A079 | |
| Person / Time | |
|---|---|
| Issue date: | 02/04/2025 |
| From: | Lucas Kyriazidis NRC/RES/DSA/FSCB |
| To: | |
| References | |
| Download: ML25035A079 (1) | |
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Updates on NRC ATF/LEU+/HBU Back-end Activities Lucas Kyriazidis Office of Nuclear Regulatory Research Division of Systems Analysis Fuel & Source Term Code Development Branch ATF/LEU+/HBU Workshop - Review of Technical Readiness for Fresh and Spent Fuel Storage & Transportation February 11, 2025
Motivation & Objectives Purpose Provide a snapshot of recently completed research related to fresh & spent fuel storage and transportation, covering topics related to:
Accident Tolerant Fuels Extended Enrichment Higher Burnup Fuels (> 45 GWd/MTU)
Highlighted Today New HBU PWR Radiochemical Assay Data & NUREG/CR-7303 Assessing the Impacts of ATF/HBU/EE for Spent Fuel Applications (NUREG/CR-7306)
Validation Studies for HBU and EE Fuels in BUC Criticality Safety Analyses (NUREG/CR-7309)
Sensitivity / Uncertainty Methods for Nuclear Criticality Safety Validation (NUREG/CR-7308) 2 NRC is performing innovative research to ensure readiness for more effective &
efficient regulatory decision-making for fresh and spent fuel storage & transportation.
2/3/2025
Recently Completed & Upcoming SNF Research 2020 - 2023 2024 - 2025 Updated Recommendations Related to Spent Fuel Transport and Dry Storage Shielding Analyses Feb. 2024 NUREG/CR-7302 Fuel Assembly and Irradiation Parametric Study for EE and HBU LWR Spent Nuclear Fuel in Dry Storage Casks and Transportation Packages*
Apr. 2024 NUREG/CR-7306 Phenomena Identification and Ranking Table (PIRT) for Fuel and Cladding Property Changes Relevant to SNF Storage & Transportation of ATF Concepts Oct. 2024 ML24292A170 Assessment of Gross Breaches in Nuclear Fuel Oct. 2024 ML24284A100 Assessment of Alternative Criteria for Gross Ruptures in Spent Nuclear Fuel Oct. 2024 ML24284A091 Development of Decay Heat Sensitivity Analysis Capability in SCALE/ORIGEN Jan. 2025 TBD Validation Studies for High Burnup and Extended Enrichment Fuels in Burnup Credit Criticality Safety Analyses*
2025 TBD, NUREG/CR-7309 Sensitivity / Uncertainty Methods for Nuclear Criticality Safety Validation*
2025 TBD, NUREG/CR-7308 Determination of Bias and Bias Uncertainty for Criticality Safety Computational Methods 2025 TBD Nuclide Importance to Criticality Safety, Decay Heat, and Radiation Shielding Analyses for Transport and Storage of non-LWR Fuel (supported by DNCSH program) 2025 TBD Assessment of Existing Transportation Packages for Use with HALEU Sept. 2020 ML21040A518 Isotopic and Fuel Lattice Parameter Trends in EE and HBU LWR Fuel (PWR)
Feb. 2021 ML21088A336 Isotopic and Fuel Lattice Parameter Trends in EE and HBU LWR Fuel (BWR)
Mar. 2021 ML21088A354 Ext. Enrichment Accident Tolerant LWR Fuel Isotopic and Lattice Parameter Trends Mar. 2021 ML21088A254 Impacts of LEU+ and ATF on Fresh Fuel Storage Criticality Safety Feb. 2022 ML22098A137 Impacts of LEU+ and HBU Fuel on Decay Heat and Radiation Source Term Apr. 2022 ML22159A191 Validating Actinides and Fission Products for Burnup Credit Criticality Safety Analyses - Nuclide Compositions Prediction with Extended Validation Basis*
Sept. 2023 NUREG/CR-7303
- Highlighted in Todays Presentation 3
New High Burnup PWR Radiochemical Assay Data NUREG/CR-7303 - Validating Actinides and Fission Products for Burnup Credit Criticality Safety Analyses 4
2/3/2025
New High Burnup PWR Radiochemical Assay Data Prompted new NRC-sponsored high-precision RCA measurements on 8 HBU PWR (North Anna) samples (2018 - 2023)
Leveraged PWR HBU fuel segments, at ORNL, following destructive examinations for DOEs Sibling Rod Program RCA data
- Measure of the isotopic composition and concentrations of a fuel sample
- Used throughout backend applications, such as depletion code validation (e.g., SCALE)
Technical report documenting all the analytical protocols & experimentally-measured data, which is publicly available in ML23094A047.
5 8 new PWR samples In 2018, NRC sponsored efforts to investigate the data availability of HBU fuels for spent fuel applications Reviewed SFCOMPO and identified gaps in existing databases (e.g., HBU samples, >60 GWd/MTU)
Majority of available data is at lower burnups; revealing a need for new high-quality HBU data 2/3/2025
NUREG/CR-7303 - Validating Actinides and Fission Products for Burnup Credit Criticality Safety Analyses Used the 8 high-precision RCA measurements on HBU PWR samples to expand the validation basis for criticality safety analyses Burnup range 34 - 67 GWd/MTU Enrichments < 5 wt. % U-235 Data is critical in validating computer codes for estimating nuclide inventories in spent fuel ML23094A047 Burnup credit accounts for the reduced reactivity due to depletion of fissile material and buildup of fission products and actinides Provides an approach for estimating the bias and bias uncertainty from the calculated nuclide inventories from fuel depletion codes Extended the validation basis up to 80 GWd/MTU Supported by incorporating new measurement data from 129 spent fuel samples Builds upon the previous validation basis, documented in NUREG/CR-7108 New data reduced the overall keff bias uncertainty NUREG/CR-7303 6
Presented in detail by G. Procop (ORNL) 2/12.
Future RCA Measurements US industry is pursuing many new initiatives & fuel designs
- Near-term and long-term accident tolerant fuel designs, such as coated claddings & doped fuels,
- Current fuel designs with higher burnups (80 GWd/MTU) and increased U-235 enrichment (10 wt. %),
- New operating conditions (e.g., uprated powers)
Future efforts to review and generate new RCA data for code validation
- Identify where new experimental data would be beneficial & critically needed
- Perform new RCA measurements to address any new identified data gaps
- Assess and update the bias and bias uncertainty with new RCA data Non-LWR efforts informed by upcoming NUREG/CR Nuclide Importance to Criticality Safety, Decay Heat, and Radiation Shielding Analyses for Transport and Storage of non-LWR Fuel, supported by the DNCSH program DOE/NRC Collaboration for Criticality Safety Support for Commercial-scale HALEU for Fuel Cycles and Transportation Technical assessment that rank the nuclides found in non-LWR fuel in terms of their importance to criticality safety, decay-generation, and shielding Considers PBMRs, SFRs, FHRs, MSRs, and HP microreactors 7
2/3/2025
Assessing the Impacts of ATF / HBU / EE for Spent Nuclear Fuel Applications 8
2/3/2025
NUREG/CR-7306 - Parametric Study for EE/HBU for Dry Storage Casks and Transportation Packages NUREG/CR-7306 Supports identifying recommendations to NUREG-2215 (SRP for spent fuel dry storage systems and facilities) & NUREG-2216 (SRP for transportation packages for spent fuel and radioactive material) for HBU/EE fuel designs Used SCALE 6.3 to perform comprehensive parametric studies to determine the effects of various fuel assembly, irradiation, and decay parameters have on decay heats, dose rates & criticality
- Fuel burnups up to 75 GWd/MTU,
- Enrichments up to 8 wt. % U-235,
- Cooling times up to 100 years,
- Specific power between 15 - 50 MW/MTU,
- Effects of soluble boron during operations (600 - 1800 ppm),
- Many other parameters investigated (e.g., burnable absorbers, fuel density, fuel temperature, coolant void, etc.).
Provide general insights on the impacts of extended enriched and higher burnup fuels have on radiation shielding and criticality safety analyses (10 CFR Part 70, 71, and 72 analyses) based on various fuel design and irradiation conditions 9
Presented in detail by A. Alpan (ORNL) 2/11.
NUREG/CR-7306 - Parametric Study for EE/HBU for Dry Storage Casks and Transportation Packages Neutron dose rates as a function of fuel burnup and fuel enrichment for PWR fuel assemblies; dry storage casks (left) and transportation packages (right).
10 Insights generated for both dry storage casks and transportation packages. Increasing burnup and enrichment has a competing effect on neutron dose rate.
Burnup - Neutron Dose Rate Enrichment - Neutron Dose Rate Not likely with proposed fuel management strategies Not likely with proposed fuel management strategies 2/3/2025
NUREG/CR-7306, Revision 1 - Parametric Study for EE/HBU for Dry Storage Casks and Transportation Packages Revision corrects an error identified in the neutron and gamma sources for both PWR & BWR case studies.
In Revision 0, neutron and gamma source terms utilized
- For PWRs -the nuclide inventory in all the regions of the fuel assembly.
- For BWRs -the nuclide inventory in all regions of the fuel assembly excluding the control rod blade and its absorber material.
In Revision 1, the source term is correctly generated, only accounting for the fueled regions.
Main observable changes in dose rate trends with the correction for neutron dose rates in the soluble boron and burnable absorber studies All plots have been updated, along with updates to the text discussing figures 11 NUREG/CR-7306, Revision 1 DRAFT ETA Q2/Q3 2025 Revision to NUREG/CR-7306 in progress.
Revision 1 is currently under review for publication.
ETA Q1/Q2 CY2025 Revision 0, incorrectly, included the WABA in the radiative source term. WABA inserts are removed after 1 cycle of operation and prior to dry storage and/or loading within transportation packages. Revision 1 corrects this error.
Validation Studies for HBU and EE Fuels in BUC Criticality Safety Analyses 12 2/3/2025
NUREG/CR-7309 - Validation Studies for HBU and EE Fuels in BUC Criticality Safety Analyses 13 Presented in detail by W. Metwally (ORNL) 2/12.
- Provides insights on the impact of HBU/EE fuels on validating BUC criticality safety analyses
- Employes the approach outlined in NUREG/CR-7109
- Performed a detailed similarity assessment study, identifying applicable critical experimental benchmarks using both ENDF/B-VII.1 & VIII.0 nuclear data libraries
- Identified French HTC critical benchmarks continue to provide relevant validation cases for BUC including EE and HBU
- Presents the bias and bias uncertainty, nuclear data-induced uncertainties and sensitivities, along with BUC loading curves DRAFT ETA Q1/Q2 2025 Application Case - HBU/EE fuels, up to 80 GWd/MTU between 5 to 8 wt. % U-235 Provides general insights on the impacts of HBU/EE fuels on the validation of BUC for criticality safety applications. NUREG/CR-7309 concludes that both ENDF/B-VII.1 & VIII.0 nuclear data libraries can be used effectively for validating BUC criticality safety analyses and the recommendations made in NUREG/CR-7109 were still found to be applicable.
Validation ensures confidence in a computer codes predictive solutions - compares the calculational method (keff) with similar and applicable critical benchmarks
Future Related Work US industry is pursuing many new initiatives & fuel designs (near-and long-term ATF concepts)
- NUREG/CR-7309 is limited to HBU fuels up to 80 GWd/MTU (assembly average) and enrichments up to 8 wt.
% U-235
- Near-term ATF concepts (i.e., Cr-dopants and Cr-coatings) are not expected to adversely affect the number of applicable critical benchmarks (similarity)
Systems are not fundamentally different than current designs (uranium oxide fuels with Zirconium-based claddings)
Mid-to longer-term ATF concepts may require future efforts 14 2/3/2025
Sensitivity / Uncertainty Methods for Nuclear Criticality Safety Validation 15 2/3/2025
NUREG/CR-7308 - Sensitivity / Uncertainty Methods for Nuclear Criticality Safety Validation 16 NUREG/CR-7308 is a comprehensive technical report on sensitivity / uncertainty methods for nuclear criticality safety validation. The report provides users expert guidance and recommendations for S/U methods. Recommendations are provided to code developers and expert users, focusing on effectively and correctly using SCALE / TSUNAMI for S/U analysis.
Presented in detail by U. Mertyurek (ORNL) 2/12.
NUREG/CR-7308 DRAFT ETA Q1/Q2 2025
- Provides a one-stop comprehensive NUREG/CR, highlighting best practices and recommendations for using S/U tools for nuclear criticality safety validation
- NUREG/CR presents
- Literature review conducted on historic use of S/U methods
- Theoretical background on S/U analyses applied to NCS
- Application recommendation for S/U methods
- Three case studies examined, demonstrating the S/U methods documented within the NUREG/CR, using SCALE TSUNAMI
- Drum-Type package containing TRISO fuel
Summary of Completed and Ongoing Research on ATF/LEU+/HBU Back-end Activities Lucas Kyriazidis Office of Nuclear Regulatory Research Division of Systems Analysis Fuel & Source Term Code Development Branch Lightning Talks ATF/LEU+/HBU Workshop - Review of Technical Readiness for Fresh and Spent Fuel Storage & Transportation February 13,2025
18 Recently Completed / Near-Completed Research NUREG/CR-7303
- Many upcoming NUREG/CRs focusing on front and backend activities, focusing on developing staff tools & reports for efficient regulatory decision-making.
- NUREG/CR-7303 - Validating Actinides and Fission Products for Burnup Credit Criticality Safety Analyses
- NUREG/CR-7306 Revision 1 - Parametric Study for EE/HBU for Dry Storage Casks and Transportation Packages
- NUREG/CR-7309 - Validation Studies for HBU and EE Fuels in BUC Criticality Safety Analyses
- NUREG/CR-7308 - Sensitivity / Uncertainty Methods for Nuclear Criticality Safety Validation Upcoming NUREG/CRs related to front & backend fuel cycle topics.
2/3/2025