How to generate the data of Photoatomic in h5 format by myself through the file of mcplib84?

User Support
1

I know I can download the ENDF/B-VIII.0 zip at Official Data Libraries | OpenMC, but I’d like to know how the photon in it was converted to get it, to help myself to Learn how to convert data from mcplib84 to h5 format.

2

Perhaps one of the convert mcnp scripts here is helpful

3

Thank you, Shimwell, I read your link which contains the conversion of ‘Lib80x’ and ‘ENDF80SaB’. Maybe I can learn how to convert other databases through it?
Also, if openmc have any official database that be directly converted to HDF5 format? like:
MCPLIB84 | Nuclear Data (lanl.gov),
ENDF7u | Nuclear Data (lanl.gov)

4

The following script:
https://github.com/openmc-dev/data/blob/master/generate_jeff33.py

will generate ENDF80 photon XS data.

ENDF80 photon data actually comes from EPICS2017

https://www.nndc.bnl.gov/endf-b8.0/
https://www.nndc.bnl.gov/endf/epics/

mcplib84 is based on EPDL97
https://www-nds.iaea.org/epdl97/

EPICS2017 is just a newer version of EPDL97, indeed EPICS2012, 2014 can be found in MCNP

https://nucleardata.lanl.gov/ace/eprdata12
https://nucleardata.lanl.gov/ace/eprdata14

There are very few differences between the libraries (97,12,14,17), I could only imagine using the older ones for some benchmarking or 1:1 comparisons

5

Just an FYI if anyone else stumbles on to this post looking for reasons for discrepancies of gamma spectra between MCNP and OpenMC like I did:
I observed a noticeable difference, above a few percent, when comparing gamma doses with low energy source (Cs-137) calculated with MCNP and OpenMC. When comparing doses for higher energy sources this discrepancy wasn’t present - likely masked by the high energy contribution to the total dose.

Tracked the origin of the discrepancy down to the nuclear data - mcplib84 in MCNP and EPICS2017 based photo atomic data OpenMC used (Thanks @yrrepy for that insight) in the distribution of ENDF/B-VIII.0. Re-ran the problem with the recently released LANL EPRDATA25 ( EPRData25 | Nuclear Data ) and ENDF/B-VIII.1 from the OpenMC site ( Cross sections - OpenMC ) and the match is basically perfect.

I will take this opportunity to put forward a proposal/suggestion to the OpenMC ND team: A more transparent way to track the origin of the nuclear data would be super useful. I would both note it on the download site and, if possible, actually bake into the hdf5 files themselves. Maybe something to consider for future nuclear library releases? If other users agree, I’ll open a feature request.

6

I’d be for providing one, maybe both, suggestions in your proposal, @BorAtBH. Would you be willing to open an issue on the repo?

7

Great, glad to see the support. Opened the issue: Save/document source of Nuclear Data in HDF5 files and data download site · Issue #4075 · openmc-dev/openmc · GitHub