processing TENDL photon cross sections with IncidentPhoton and finding atomic relaxation

User Support
1

Hi all

Just wondering if anyone has had any luck processing TENDL 2015 or TENDL 2017 photon files for use in OpenMC using the openmc.data.IncidentPhoton method

From the 2015 TENDL website (https://tendl.web.psi.ch/tendl_2015/tar.html)I have downloaded gamma library files from https://tendl.web.psi.ch/tendl_2015/tar_files/ACE-g.tgz but I have attached a single photon ace file.

I have been using IncidentPhoton.from_ace without any relaxation information, but from the error it looks like the atomic relaxation is not included in the ACE file so I was wondering if anyone knows where it might be found.

Many thanks

Jon

A minimal example is …

import openmc.data

data = openmc.data.IncidentPhoton.from_ace(‘Zr080-g.ace’)

The resulting error is …

data = openmc.data.IncidentPhoton.from_ace(‘Zr080-g.ace’)
/home/jshim/.local/lib/python3.6/site-packages/openmc-0.11.0.dev0-py3.6-linux-x86_64.egg/openmc/data/photon.py:1125: RuntimeWarning: overflow encountered in exp
xs[nonzero] = np.exp(xs[nonzero])

Zr080-g.ace (1.25 MB)

2

Unfortunately the TENDL webpage is not very precise in their terminology. What they call “gammas” or “photons” is actually photonuclear data, not photoatomic. OpenMC does not yet handle photonuclear data/interactions. That being said, the error that you get is not very helpful. I’m about to submit a PR adding a check that from_ace gets the correct type of ACE table.

Best,
Paul

3

Thanks Paul much appreciated

4

It has been a while, but try at TENDL-2021 nuclear data library at the bottom of that page below 7 gamma

If you have issues, just tell me solutions exists