ML26033A308
| ML26033A308 | |
| Person / Time | |
|---|---|
| Issue date: | 02/03/2026 |
| From: | Lucas Kyriazidis NRC/RES/DSA/FSCB |
| To: | |
| References | |
| Download: ML26033A308 (0) | |
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Nuclear Data in the Regulatory Framework Workshop for Applied Nuclear Data Activities (WANDA) 2026 February 9, 2026 Lucas Kyriazidis US Nuclear Regulatory Commission Office of Nuclear Regulatory Research Division of Systems Analysis
Nuclear Data in the Regulatory Framework Nuclear data is essential across many regulatory areas:
NRC licensing activities (independent & confirmatory analyses)
Model development & validation of NRCs safety computer codes NRC relies on high-quality, comprehensive nuclear data for:
Non-LWR construction permit licensing reviews Spent fuel pool criticality safety analyses Criticality, shielding, and decay heat analyses for storage and transportation Burnup credit analyses Performing accident safety analyses throughout the fuel cycle Nuclear data supports NRC regulatory decision-making activities, such as reactor power uprates, new fuel designs, new transportation package designs, and advanced reactor designs.
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Computational Tools Supporting Regulatory Decision-Making & Safety Analysis 3
Nuclear data & cross-section processing Decay heat, criticality safety, radiation shielding Radionuclide inventory & depletion generation Reactor core physics Core simulator (nodal diffusion for transport)
Solutions for core-wide & assembly power Quasi-steady-state depletion - inter and intra fuel cycle analysis (fuel shuffle)
Transient analysis (coupled to TRACE)
Accident progression & source term characterization Thermal-hydraulic response of the reactor Core heat-up, degradation, and relocation Fission product release and transport behavior Design basis accidents & anticipated operational occurrences Couple thermal-hydraulic & neutronics response Core heat-up with transient progression
Nuclear Data Supporting Regulatory Analyses SCALE is the first step in processing nuclear data for developing problem-specific libraries
- Confidence in SCALEs predictive solutions rely on quality and complete nuclear data
- Requires measured mean values and associated uncertainties 4
ENDF/B Physics data Thermal scattering law Resonance data Energy distributions Fission yields, decay constants, decay energy Recoverable energy Delayed neutron data Activation (JEFF-3.0/A)
Activation reactions Fusion (FENDL)
Activation reactions Nuclear Data Sources Includes all applicable uncertainties ORIGEN - Fuel Depletion, Decay, and Activation Decay Data - half lives, branching fractions, decay energy release Cross-sections Gamma ray production Fission product yields Neutron production data Polaris / TRITON / KENO / MAVRIC / Shift - Radiation Transport Cross-sections Gamma ray production Fission product yields Neutron production data ORIGEN reactor libraries - Assessed MG Cross-section libraries LWR Libraries - PWRs & BWRs Non-LWR libraries - SFRs, HTGRs, FHRs, Microreactors, MSRs.
5 Types of NRC nuclear data needs Large uncertainties in nuclear data, such as cross-sections, fission yields, and decay data, can propagate into increased uncertainties in key quantities of interests, used to support NRC activities (i.e., k-effective for criticality safety analyses, calculated reactivity coefficients for reactor physics applications). Key nuclear data activities, supporting the NRC, include ensuring nuclear datasets, including uncertainties are complete for the application areas mentioned.
Ongoing Activities at the NRC Impacted by Nuclear Data Fusion Non-Light Water Reactors Microreactors Sodium Fast Reactors Liquid Salt Fueled Reactors (MSRs)
Pebble-Bed Reactors (FHRs
& HTGRs)
Light Water Reactors Long-Term ATF Near-Term ATF Power Uprates
- Extended Enrichment - up to 10 wt.% U-235
- High burnup - up to 80 GWd/MTU
- New fuel designs - coated claddings, additive fuels, new claddings & fuel types
- Spectrum - fast, epithermal, and thermal systems
- Moderators - graphite, helium
- Neutron-activation &
interaction nuclear data
- Neutron irradiation damage
Research Supporting Identifying Key Nuclides Important to NRC-applications 6
NUREG/CR-6700 Radionuclides of Interest Nuclear data needs focus on specific data that impact key quantities of interest that support regulatory applications Assessments identifying nuclide importance related to backend applications LWRs - NUREG/CR-6700 Non-LWRs - NUREG/CR-TBD (ETA 2026)
Focuses on nuclides that impact criticality, shielding, decay heat analyses Identifying Nuclear Data Needs 1.
Nuclides that impact key quantities that support NRC activities 2.
High-quality and complete nuclear data evaluations, including comprehensive uncertainty information 3.
Enables uncertainty quantification and sensitivity analyses for nuclides that exhibit significant bias in key NRC quantities of interest while having small reported uncertainties
Reference:
Nuclide Importance to Criticality Safety, Decay Heating, and Source Terms related to Transport and Interim Storage of High-Burnup LWR Fuel (NUREG/CR-6700, ORNL/TM-2000/284). Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, D.C. January 2001.
ETA 2026
NUREG/CR-7289 Non-LWR Nuclear Data Assessment - NUREG/CR-7289 Identified key nuclear data relevant to reactor safety analysis for selected non-LWR technologies Graphite-rich designs (pebble-bed systems)
Complete nuclear data for graphite including thermal scattering law uncertainty data Salt-based designs (fueled & cooled systems)
Salts may make use of Lithium-7 (e.g., Flibe). Large uncertainty in Li-7(n,) has found to be a dominating contributor to impacting reactivity effects.
Impact of Nuclear Data Libraries Understanding the differences between nuclear data libraries which impact reactivity (ENDF/B VII.1 to VIII.0) (e.g., Cl-35) 7 DOE/NRC Collaboration for Criticality Safety Support for Commercial-scale HALEU Fuel Cycles and Transportation New US program that addresses critical HALEU-related data needs Ongoing experiments that will generate new graphite scattering and Cl-35 cross-section data, which includes new measurements, evaluations, and validation 1.
Thermal/Epithermal eXperiements (TEX) Additional Chlorine Configurations to Provide Validation for TerraPowers Molten Chloride Salt Fuel 2.
High-Temperature Graphite Double Differential Scattering Cross Sections: Measurements, Evaluations, and Validation
Reference:
Nuclear data assessment for advanced reactors (NUREG/CR-7289, ORNL/TM-2021/2002).
Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, D.C. March 2022.
Other Nuclear Data Related Research Activities at the NRC As new ENDF/B libraries are released, NRC assesses these libraries on their impacts to NRC-applications ENDF/B VII.1 / VIII.0 / VIII.1 Assessment documented in SCALE validation reports Recent efforts to begin assessing ENDF/B-VIII.1 for NRC-applications underway Understanding changes in k-effective and/or nuclide inventories with different ENDF/B libraries (VII.1, VIII.0, and VIII.1)
New efforts underway to automate testing, in SCALE, of new evaluated nuclear data libraries Rapidly assess ENDF/B beta & production libraries Allows for greater opportunities for collaboration by providing evaluators feedback 8
Extensive SCALE validation completed across reactor physics, criticality safety, shielding, and spent fuel applications. Efforts can be leveraged to provide valuable feedback to the nuclear data evaluators and community.