error when material density < 1

[LukeLabrie]

when I run openmc-plotter, if any material in my materials.xml file has a density < 1.0 g/cm3, I get

 ERROR: Need to specify a positive density on material [material_id]

I first noticed on a helium material (density on the order of 1e-4 g/cm3), but while debugging I noticed that I still get it even at 0.99 g/cm3, but not at 1.0 g/cm3. Not sure if this is by design perhaps.

[pshriwise]

Hi @LukeLabrie,

Thanks for reporting this! It's definitely not intended behavior. I tried changing a couple of material densities in my model, but I didn't see this error show up. Could you let us know what version of the plotter you're using when you have a chance?

[LukeLabrie]

Hi @pshriwise , apologies for the late response. I'm actually having a hard time figuring that out. Tried openmc-plotter --version, and tried clicking around the GUI a little bit. Where can I see the version?

To install initially I just used pip install openmc-plotter

[pshriwise]

Hrmmm you're right @LukeLabrie. There isn't an easy way to get that info once you've installed the tool. I've just added an option for that in #98. That might not help us here though. I think you'll need to reinstall and look through the output of the pip install command to find the version number of the package. Sorry about that.

[pshriwise]

@LukeLabrie are you still having problems with this?

[LukeLabrie]

Hi @pshriwise, I uninstalled and reinstalled. Looks like I have version 0.2.0

Installing collected packages: openmc-plotter
Successfully installed openmc-plotter-0.2.0

I still run into the same issue:

 Reading settings XML file...
 Reading cross sections XML file...
 Reading materials XML file...
 ERROR: Need to specify a positive density on material 7.
QObject::~QObject: Timers cannot be stopped from another thread

Here is the .xml entry for reference:

  </material>
  <material id="7" name="helium" temperature="911.15">
    <density units="g/cm3" value="0.00103" />
    <nuclide ao="2e-06" name="He3" />
    <nuclide ao="0.999998" name="He4" />

[pshriwise]

I'm still having trouble reproducing this... The type of error you're seeing looks like it's coming from the OpenMC executable itself. Is it the case that you can run this model, but you cannot view it in the plotter?

[LukeLabrie]

Yes and no. I can run the model but it fails due to lost neutrons. Was hoping to use the plotter to identify overlaps, which I can as long as I go in and raise the densities where needed.

[letibdesneiges]

Hi,

I encountered the same problem with a model containing air with a density of 1.293e-3 g/cm3. It request a density >0. Changing the density in the xml file to >=1 g/cm3 fixed it and openmc-plotter launched without error.

Attached the model.xml file causing the problem on my side. model.xml.zip

openmc-plotter 0.3.1 installed via conda on Debian 11.

[paulromano]

@letibdesneiges Very strange -- when I throw your model into the plotter on my end, I don't get any such error :confused: I also tried installing the plotter through conda-forge and still no problems.

[letibdesneiges]

@paulromano Yes, I tried again with a fresh conda install using python 3.10 (the previous one was with python 3.9). Still the same problem with the xml file linked above. Here is a screenshot of the error while loading. The same file can be used by openmc. Could it be encoding or locale related ?

[paulromano]

@letibdesneiges That's an interesting hypothesis and could explain why you are seeing it but not me. If you try to run OpenMC using this model, do you get the same error about positive density, or does this only occur when you load the model in the plotter?

[shimwell]

I sat in the adjacent seat at the NEA and can confirm this bug only occurred when plotting with the plotter. The model ran fine with openmc and produced nice mesh tally plots. I also saw the changes to the XML file and the plotter working afterwards

[paulromano]

This same issue was discussed in #124 and already resolved