Cross sections

Data¶

Official Data Libraries¶

The data libraries listed here have been produced by the OpenMC development team and are as complete as possible. HDF5 files are created by first processing source ENDF files into ACE files and then using the openmc.data Python module to convert ACE data into HDF5. The entire process is automated by the IncidentNeutron.from_njoy method which calls NJOY under the hood to produce ACE files.

ENDF/B-VII.1¶

This library includes incident neutron, photoatomic, thermal scattering, and windowed multipole data. All ACE files were produced using NJOY 2016.68. Incident neutron data is available at six temperatures: 250 K, 293.6 K, 600 K, 900 K, 1200 K, and 2500 K. Note that elastic scattering cross sections are also available at 0 K and and can be used for modeling resonance upscattering in heavy nuclides. Thermal scattering data is available at the tabulated temperatures from the source ENDF files. Windowed multipole data can be used to evaluate temperature-dependent cross sections at run-time.

Downloads: ENDF/B-VII.1

ENDF/B-VIII.0¶

This library includes incident neutron, photoatomic, atomic relaxation, and thermal scattering data from ENDF/B-VIII.0. All ACE files were produced using NJOY 2016.68. Incident neutron data is available at six temperatures: 250 K, 293.6 K, 600 K, 900 K, 1200 K, and 2500 K. Thermal scattering data is available at the tabulated temperatures from the source ENDF files.

Downloads: .tar.xz

JEFF 3.3¶

This library includes incident neutron and thermal scattering data from JEFF 3.3. All ACE files were produced using NJOY 2016.68. The photoatomic and atomic relaxation data from ENDF/B-VIII.0 has also been included because JEFF 3.3 does not release its own photoatomic or atomic relaxation sublibraries. Incident neutron data is available at six temperatures: 250 K, 293.6 K, 600 K, 900 K, 1200 K, and 2500 K. Thermal scattering data is available at the tabulated temperatures from the source ENDF files.

Note that the C13 and O17 cannot be processed by NJOY 2016.68 due to a bug in the evaluations. These nuclides have been replaced by data from TENDL-2019 (the original evaluations from JEFF 3.3 were taken from TENDL-2015).

Download: .tar.xz

LANL-Based Data Libraries¶

ENDF/B-VII.0¶

This library was produced by converting ACE files generated by the Nuclear Data Team at LANL and distributed with MCNP5/6. Incident neutron data was converted from endf70[a-k] files, thermal scattering data from endf70sab, and incident photon data from the eprdata14 library. Incident neutron data is available at five temperatures: 293.6 K, 600 K, 900 K, 1200 K, and 2500 K. For further information on the source data, please see LANL technical reports LA-UR-08-1999 and LA-UR-08-3628.

Download: .tar.xz

ENDF/B-VII.1¶

This library was produced by converting ACE files from the endf71x and ENDF71SaB libraries that were generated by the Nuclear Data Team at LANL and distributed with MCPN5/6. Incident neutron data is available at seven temperatures: 0.1 K, 250 K, 293.6 K, 600 K, 900 K, 1200 K, and 2500 K. Incident photon data converted from the eprdata14 library is also included. For further information on the source data, please see LANL technical reports LA-UR-13-20137 and LA-UR-14-21878.

Download: .tar.xz

ENDF/B-VIII.0¶

This library was produced by converting ACE files from the Lib80x and ENDF80SaB2 libraries that were generated by the Nuclear Data Team at LANL. Incident neutron data is available at seven temperatures: 0.1 K, 250 K, 293.6 K, 600 K, 900 K, 1200 K, and 2500 K. For more information on the source data, please see LANL technical reports LA-UR-18-24034 and LA-UR-20-24456.

Download: .tar.xz

Other Data Libraries¶

JEFF 3.2¶

This library was produced by converting ACE files generated by NEA. It includes incident neutron data as well as thermal scattering data for 10 different compounds. Incident neutron data is available at 12 temperatures: 293 K, 300 K, 400 K, 500 K, 600 K, 700 K, 800 K, 900 K, 1000 K, 1200 K, 1500 K, and 2500 K.

Note: This particular library requires that you use HDF5 1.10+ when building OpenMC.

Download: .tar.xz

JEFF 3.3¶

This library was produced by converting ACE files generated by NEA. It includes incident neutron data as well as thermal scattering data for 21 different compounds. Incident neutron data is available at 6 temperatures: 293.6 K, 600 K, 900 K, 1200 K, 1500 K, and 1800 K.

Download: .tar.xz

FENDL 3.2¶

This library was produced by converting ACE files generated by IAEA NDS. It includes neutron data for 192 nuclides as well as photoatomic data for 61 elements. Incident neutron data is available at 293.6 K.

Download: .tar.xz

Depletion Chains¶

In order to perform depletion analysis using the OpenMC depletion module, a representation of the depletion chain must be presented. This chain describes transmutation and decay channels causing isotopes to evolve over time. XML-representations of these depletion chains can be built using evaluated nuclear data libraries. OpenMC provides functions and scripts to generate these chain files using a collection of neutron interaction, neutron-induced fission, and decay files. Alternatively, three pre-generated chain files are made available using ENDF/B-VII.1 data distributed with OpenMC.

ENDF/B-VII.1 Chain (Thermal Spectrum)¶

Provided here is a complete depletion chain containing all isotopes with cross sections, neutron-induced fission yield data, and decay data as contained in the ENDF/B-VII.1 libraries distributed with OpenMC. Capture branching ratios are taken to be identical to the default branching ratios used in the Serpent Monte Carlo code, corresponding to a typical PWR spectrum.

Download:

for version 0.11 .xml for version 0.12+ .xml

ENDF/B-VII.1 Chain (Fast Spectrum)¶

Provided here is a similar complete depletion chain, but using capture branching ratios that are more representative of a sodium fast reactor (SFR). Branching ratios were computed by tallying total capture reaction rates, capture to ground, and capture to metastable states for specific isotopes. The effective branching ratios were taken to be the ratio of reactions to ground to total number of capture reactions for each isotope.

Download:

for version 0.11 .xml for version 0.12+ .xml

ENDF/B-VIII.0 Chain (Thermal Spectrum)¶

This is a complete depletion chain generated based on the incident neutron, decay, and neutron fission yield sublibraries from ENDF/B-VIII.0. Capture branching ratios are taken to be identical to the default branching ratios used in the Serpent Monte Carlo code, corresponding to a typical PWR spectrum.

Download: .xml ENDF/B-VIII.0 Chain (Fast Spectrum)

This is a complete depletion chain generated based on the incident neutron, decay, and neutron fission yield sublibraries from ENDF/B-VIII.0. Capture branching ratios used within are representative of a sodium fast reactor (SFR). Branching ratios were computed by tallying total capture reaction rates, capture to ground, and capture to metastable states for specific isotopes. The effective branching ratios were taken to be the ratio of reactions to ground to total number of capture reactions for each isotope.

Download: .xml Simplified Chain (Thermal Spectrum)

Provided here is a simplified depletion chain using isotopes recommended by Appendix A of Kang Seog Kim, “Specification for the VERA Depletion Benchmark Suite”, CASL-U-2015-1014-000, Rev. 0, ORNL/TM-2016/53, 2016. Te129 has been included, due to its link to I129 production. Capture branching ratios representative of a PWR spectrum are applied to relevant isotopes.

Download:

for version 0.11 .xml for version 0.12+ .xml

Simplified Chain (Fast Spectrum)¶

Provided here is a simplified depletion chain using isotopes recommended by Appendix A of Kang Seog Kim, “Specification for the VERA Depletion Benchmark Suite”, CASL-U-2015-1014-000, Rev. 0, ORNL/TM-2016/53, 2016. Te129 has been included, due to its link to I129 production. Capture branching ratios representative of an SFR spectrum are applied to relevant isotopes.

Download:

for version 0.11 .xml for version 0.12+ .xml

Capture Branching Ratios¶

Below are links to tabulated representations of the capture branching ratios computed using PWR and SFR spectra. The PWR branching ratios are taken from the Serpent Wiki. The SFR branching ratios are computed by computing one group total capture, capture to ground, and capture to metastable states in an SFR assembly.

PWR Spectrum Capture Branching Ratios SFR Spectrum Capture Branching Ratios