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DOE OSTI2024

ENDF/B-VIII.1: Neutron Reaction Sublibrary

The neutrons sublibrary aims to describe nuclear reactions between incident neutron particles and different nuclei. For ENDF/B-VIII.1, many neutron files were re-evaluated or received major changes. A new 239Pu evaluation was jointly-produced by IAEA, LANL, LLNL and ORNL bringing important updates to fission neutron multiplicity, Prompt Fission Neutron Spectrum, resonance and fast regions. Around one third of the new neutron evaluations were performed as part of the INDEN collaboration, including 16,18 O, 19 F, 28,29,30 Si, 63,65 Cu, 50,51,52,53,54 Cr, 55 Mn, 54,56,57 Fe, 139 La, 233,235,238 U, 240,241 Pu. Important non-INDEN evaluations include 234,236 U, 206,207,208 Pb, 181 Ta, 88 Sr, 140,142 Ce, Pt and Dy isotopes, and many others. Also, dosimetry reactions from IRDFF-II were adopted for many materials.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ENDF/B-VIII.1: Neutron Induced Fission Product Yields Sublibrary

The neutron-induced fission yields (NFY) sublibray aims to describe fission yields in neutron-induced reactions. For ENDF/B-VIII.1, there were no new fission yields complete evaluations. However, an important fix the 241 Pu NFY file was implemented, solving a long-standing anomalous discontinuity issue accidentally introduced in ENDF/B-VI.2, decades ago. Additionally, many erroneously large uncertainties, present in NFY from ENDF/B-VIII.0, were corrected.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ENDF/B-VIII.1: Photoatomic Reaction Sublibrary

The photo-atomic sublibrary aims to describe atomic photon cross section data, corresponding to the interaction between photons and the different atoms. For ENDF/B-VIII.1 we adopted the EPICS2023 EPDL evaluations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ENDF/B-VIII.1: Proton Reaction Sublibrary

The protons sublibrary aims to describe nuclear reactions between incident proton particles and different nuclei. For ENDF/B-VIII.1, compared to ENDF/B-VIII.0, there were only evaluation updates for 4 He.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ENDF/B-VIII.1: Spontaneous Fission Product Yields Reaction Sublibrary

The spontaneous fission yields (SFY) sublibray aims to describe fission yields that happen spontaneous, without any incident particle. For ENDF/B-VIII.1, there were no new fission yields complete evaluations. However, many erroneously large uncertainties, present in both SFY from ENDF/B-VIII.0, were corrected.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ENDF/B-VIII.1: Neutron Standards Sublibrary

The neutron standards sublibrary describes specific reaction cross sections, in a limited range, that are so well-known that they are used as ratios or references in other measurements. ENDF/B-VIII.1 remains unchanged from ENDF/B-VIII.0 for the neutron standards sublibrary

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ENDF/B-VIII.1: Triton Reaction Sublibrary

The tritons sublibrary aims to describe nuclear reactions between incident triton particles and different nuclei. For ENDF/B-VIII.1, compared to ENDF/B-VIII.0, there were only evaluation updates for 4 He.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

On Integral Benchmarks for Resolving TSL Conflicts for ENDF/B-VIII.1 Release [Slides]

This presentation touches on polystyrene ORNL evaluation in TSL review process for ENDF/B-VIII.1. the presentation found excellent agreement with INS and transmission measurements. Additionally, PS and PE evaluations with different phonon spectra, similar total xs., calculate keff similarly. This presentation found for critical benchmarks. While extremely useful for validation of nuclear data at all energies, critical benchmarks are not the best tool to provide a definitive answer on conflicting TSLs. In conclusion this presentation found INS and transmission measurements need to be the basis of validation of TSLs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Covariance Testing Progress for ENDF/B-VIII.1β1 at ORNL [Slides]

This presentation touched on how data-induced uncertainty significantly increased for thermal 235 U-fueled systems. And how 239 Pu covariance changes are worrying. Additionally discussed is how 103 Rh is the only significant important fission product change. The Impact of ENDF/B-VIII.1β1 on burnup credit similarity assessments is similar to ENDF/B-VII.1 data.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Contributions for ENDF/B-VIII.1 Paper

This paper is on contributions for ENDF/B-VIII.1. The paper covers neutron reaction covariances and touches on improved testing of nuclear data covariances. Additionally, fission is discussed along with the prompt fission neutron spectrum. Finally, it ends with a look into validation with LLNL pulsed spheres.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

ENDF/B-VIII.1 Validation: Covariance [Slides]

This presentation touches on ENDF/B-VIII.1 Validation: Covariance. Topics include inconsistencies in the ENDF files, derived matrices, lumped reactions and process ENDF data file with PUFF. Finally correcting data with cognac and redundant covariance that are not consistent are discussed.

Cognac↗
DOE OSTI2023

Independent and cumulative thermal neutron-induced fission yields of 241 Pu for ENDF/B-VIII.1

In this work we document changes proposed to the Evaluated Nuclear Data File (ENDF/B) thermal neutron-induced fission yields of 241Pu. The issue, which consists in a nonphysical discontinuity in the yields of fission products in thirteen mass chains, was introduced in ENDF/B-VI.2 and was left unchanged in all releases up until the current release one, ENDF/B-VIII.0. After analyzing the possible origin of the problem, we implemented correction factors that restore the yields to the intended mass distributions. Both independent and cumulative yields files were corrected, and the new values included in this report have been proposed for inclusion in the upcoming ENDF/B-VIII.1 release.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Contributions for ENDF/B-VIII.1 Paper

It was discussed at WANDA2020 that some issues were found by the community and users in ENDF/B-VIII.0 covariances after their release. It was mentioned that one issue in testing ENDF/B-VIII.0 covariances was that they were provided by evaluators too late in the β-release phases that insufficient time for thorough testing was available. Therefore, the executive committee requested that first nuclear data covariances should already be delivered for ENDF/B-VIII.1β 1 in February 2023—about half a year earlier than was the case for ENDF/B-VIII.0. This additional time allowed for more stringent testing with LANL’s ENDFtk and CovVal codes, and ORNL’s AMPX code during the release phases. The LLNL covariance testing employed a combination of NJOY, empy tools from EMPIRE, and x4i.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Tables of Neutron Thermal Cross Sections, Westcott Factors, Resonance Integrals, Maxwellian Averaged Cross Sections, Astrophysical Reaction Rates, and r-process Abundances Calculated from the ENDF/B-VIII.1, JEFF-3.3, JENDL-5.0, BROND-3.1, and CENDL-3.2 Evaluated Data Libraries

We present calculations of neutron thermal cross sections, Westcott factors, resonance integrals, Maxwellian-averaged cross sections, astrophysical reaction rates, and solar system r-process abundances using the latest data from the major evaluated nuclear libraries for 849 ENDF target materials. The recent release of ENDF/B-VIII.1 library, progress in 252 Cf(SF) evaluation, extensive analysis of newly-evaluated neutron reaction cross sections, neutron covariances, and improvements in data processing techniques motivated us to calculate the nuclear industry and neutron physics parameters, produce s-process Maxwellian-averaged cross sections and astrophysical reaction rates, extract r-process abundances, systematically calculate uncertainties, and provide additional insights on currently available neutron-induced reaction data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Format Proposal for Isotopic Distribution in TSL Files for ENDF/B-VIII.1 [Slides]

This presentation proposes a format of an ‘footer’ file for ENDF6-format TSL files. This would contain several pieces of pertinent information for the scattering atom. such as the Number of scattering atoms in molecule, Isotopic distribution within scattering atom, and free atom and atomic weight ratios for each isotope. This setup will not require significant changes to processing codes or to other sections of the MF7 file.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

Resonance Parameter Evaluation of n + 88 Sr reactions for ENDF/B-VIII.1 Library

An evaluation of n+ 88 Sr reactions up to 950 keV was compiled from a publicly available set of resonance parameters. Starting from the repository of the ENDF/B-VIII.0 library, an evaluated nuclear data file was assembled and submitted for inclusion to the Evaluated Nuclear Data File (ENDF)/B-VIII.1 release. This evaluation features an external function representation defined by pole strengths and R ∞ parameters over the entire resolved resonance range. This work improves the modeling of the R-matrix parameterization from multi-Level Breit-Wigner resonance parameters to Reich-Moore formalism, and it also extends thrice the upper energy range of the current ENDF/B-VIII.0 resolved resonance evaluation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗