ML22297A032

Nuclear Data at the Us NRC

ML22297A032
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Issue date:	10/31/2022
From:	Lucas Kyriazidis Office of Nuclear Regulatory Research
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Nuclear Data at the US NRC

Lucas Kyriazidis Office of Nuclear Regulatory Research

October 2022 Nuclear Data Uncertainty Quantification Working Meeting Nuclear Data in the Regulator y Framework

Where does Nuclear Data Fit under the NRCs Regulatory Framework?

Nuclear data is used throughout the NRCs regulatory framework.

Licensing activities and decision-making in Office of Nuclear Regulatory Regulation (NRR) and Office of Nuclear Materials Safety and Safeguards (NMSS) includes review of consolidated interim storage facilities, burnup credit, analyses of spent fuel pool criticality, and generation of reactor physics and decay heat parameters for design b asis accident analysis. All of these rely on quality nuclear data (e.g., ENDF/B) utilized through its neutronics computer code package SCALE.

LWR Activities at the NRC

Near-term ATF Mid- & Long-term ATF

Higher burnup

(>75 Cr-coated GWd/MTU) & Chromium-Iron-based Zirconium Metallic Fuels (<

Increased doped fuels claddings Cladding 20 wt. % U-235)Silicon Carbide Uranium Silicide Uranium Nitride Enrichment (< (FeCrAl) Systems 10 wt. % U -235)

Does the NRC envision any nuclear data needs for LWRs, including AT F ?

Large uncertainties in nuclear data, such as cross-sections, fission yields, and decay data, can propagate into increased uncertainties in key quantities of interests (i.e., k-eff for criticality safety analyses to fuel, moderator, and void reactivity coefficients for reactor physics applications). Thus, the NRC would find it important that nuclear datasets, including uncertainties are complete for the application areas 3 mentioned.

Non-LWR Activities at the NRC

Technology & Reactor Type Key Design Characteristics Fast Spectrum Systems** Thermal Spectrum Systems**

High-Temperature Gas-Cooled

• Fuel Forms

• Graphite Moderated, Reactors

• Uranium Carbide Fuel

• Helium-cooled,

• Silicon Carbide Claddings

• TRISO particle (<20 wt.% U-235)

• Helium-cooled

Thermal Spectrum Systems*

• Graphite Moderated, Fluoride salt-cooled Reactors

• Molten fluoride salt cooled,

• FLiBe

• TRISO particle (UCO kernel) (<20 wt.% U-235)

Fast Spectrum Systems Thermal Spectrum Systems*

• Uranium-chloride salt fueled

• Molten fluoride salt, fueled with UF4 Molten Salt Reactors

• LiF, BeF2, UF4

• < 20 wt.% U-235

• Graphite moderated

Fast Spectrum Systems Sodium Fast Reactors

• High Assay LEU metallic fuels

• Sodium coolant

• Applications submitted

• • Pre-application activities (e.g., topical reports, white papers, etc.)

Non-LWR Nuclear Data Needs

• NUREG/CR-7289

- Assessment on key nuclear data relevant to reactor safety analysis in selected non-LWR technologies

Does the NRC envision any nuclear data needs for non-LWRs?

NUREG/CR-7289 identified many key isotopes for the various types of non-LWR designs on the horizon. This assessment also identified missing nuclear data. Examples include:

• Many non-LWR designs aregraphite-rich. Thus, complete nuclear data sets for graphite would be important. One key missing nuclear data identified was missing graphite thermal scattering uncertainty data.

• Nuclear data related to the salts (e.g., FLiBe) under consideration. Some salts make use of Lithium-7. Large uncertainty in Li-7(n,) has found to be a dominating contributor to impacting reactivity effects.

• Understanding the differences between nuclear data libraries which impact reactivity (ENDF/B VII.1 to VIII. 0) (e.g., Cl-35)