Python API not found using conda installation

User Support
1

I’ve done an install using miniconda of the openmc environment using the exact commands in the installation guide and all worked with no errors. I activated the environment and did a pip list to verify openmc, and it is shown,
(openmc-env) brian@1:~$ pip list
Package Version

openmc 0.15.2
<Removed all the other packages - just showing that openmc is installed per the conda environment>
When I run python in this environment, it recognizes the import openmc command and I get functionality:
(openmc-env) brian@1:~$ python
Python 3.13.9 | packaged by conda-forge | (main, Oct 16 2025, 10:31:39) [GCC 14.3.0] on linux
Type “help”, “copyright”, “credits” or “license” for more information.

import openmc
t=openmc.Sphere
print(t)
<class ‘openmc.surface.Sphere’>

However, When running in IDLE in this same environment configuration, openmc module is not found:

Python 3.12.3 (main, Aug 14 2025, 17:47:21) [GCC 13.3.0] on linux
Type “help”, “copyright”, “credits” or “license()” for more information.

================= RESTART: /home/brian/OpenMCPrograms/test2.py =================
Traceback (most recent call last):
File “/usr/lib/python3.12/idlelib/run.py”, line 580, in runcode
exec(code, self.locals)
File “/home/brian/OpenMCPrograms/test2.py”, line 1, in
import openmc
ModuleNotFoundError: No module named ‘openmc’

Same error occurs in Jupyter-notebook running in this conda environment.
import openmc

ModuleNotFoundError Traceback (most recent call last)
Cell In[1], line 1
----> 1 import openmc

ModuleNotFoundError: No module named ‘openmc’

Can someone point me where I’ve gone wrong?
Thank you.
Brian

2

Did this mean that you use the system python? You should “conda activate openmc-env”first and use the conda environment python, then “python /path/to/your/test2.py”

3

I did conda activate openmc-env to start - you can see that in the prompts above with the (openmc-env) lead on the terminal prompt. But both IDLE and Jupyter-notebook don’t recognize the import openmc command.

All the best,

Brian

4

this shows that the python version in conda environment is 3.13.9, but here

the python version is 3.12. So I think you didn’t activate the environment correctly. Maybe you can try to activate the openmc-env in a terminal and “python your_file.py”

5

You are correct about the version, though I activated it with conda activate openmc-env. I don’t know what else to do. And I’m trying to get Jupyter-notebook to recognize the import openmc command - python files run within python do work, but jupyter-notebook does not.