Error with Universe.plot in 0.13.1dev version

[SteSeg]

While trying to plot models geometry using universe.plot with the 13.1dev version I get the following error:

"RuntimeError: No cross_sections.xml file was specified in materials.xml or in the OPENMC_CROSS_SECTIONS environment variable. OpenMC needs such a file to identify where to find data libraries. Please consult the user's guide at https://docs.openmc.org/ for information on how to set up data libraries."

Additional info:

• I don't have an OPENMC_CROSS_SECTIONS env variable, I use materials.cross_sections instead, directly in the model materials definition
• Commenting out the universe.plot lines the rest of the simulation runs fine
• The same model with the 0.13.0 version runs fine and plots the geometry
• The error appears with all the models

[paulromano]

I'm working on a better solution for this, but in the meantime as a workaround, the following should work:

import os

os.environ['OPENMC_CROSS_SECTIONS'] = material.cross_sections
...
universe.plot(...)

[paulromano]

The proper solution for this now is to use openmc.config, which was introduced in version 0.13.2.