Problem with Reactor examples C0 and C12 files

User Support
1

Hello, I’m starting to use OpenMC and trying to run all the Reactor examples, nonetheless I have an issue with carbon… When looking at the examples the openmc.run() gives at some point:

“Reading C0 from /Users/miriamrathbun/codes/openmc/nucleardata/endfb71_hdf5/C0.h5”

I downloaded the cross_sections file from ENDF/B-VII.1 and it does have the C0 file for carbon, now my issue is that when I run the example in m computer I get:

"Reading C12 from /home/liliana/Desktop/FRMII/neutron/C0.h5
ERROR: Object “C12” does not exist in object / "

I’ve changed the file name to C12 to see if maybe that was the issue, I’ve tried changing the names/routes but nothing works so far.

2

I would recommend specifying the source of your cross sections using the openmc.config configuration variable at the top of your script/notebook. Documentation on this is available here but would look like:

openmc.config['cross_sections'] = '/some/directory/cross_sections.xml'

This ensures that the same set of nuclides is used 1) when generating XML files and 2) when actually running OpenMC. The error you are seeing can happen if there is a mismatch between the nuclides used in one versus the other.