OpenMC Windows Installation Guide (v0.1-beta)

• This is beta version; hence number of particles is restricted to 10000, and batches to 200.
• Get the stable full version at: OpenMC Windows Page
• Fill this form to know future updates: Google Form
• Installing video guide: https://www.youtube.com/
• Technical Note: OpenMC_Windows_Technical_Note_sachin.pdf

Author:
Sachin Shet
LinkedIn

System Requirements

• Windows 10 or Windows 11 (64-bit)
• Python 3.10 or newer
• pip installed and available in the system PATH
• ENDF/B HDF5 cross section library (cross_sections.xml)

Step 1 – Install Python

Download Python from: https://www.python.org/downloads/windows/

Link: https://www.python.org/ftp/python/3.14.6/python-3.14.6-amd64.exe

During installation enable:

• Add Python to PATH

Verify:

python --version
python -m pip --version

Step 2 – Prepare Nuclear Data

Download Nuclear data from OpenMC Website https://openmc.org/data/

Link: https://anl.box.com/shared/static/9igk353zpy8fn9ttvtrqgzvw1vtejoz6.xz

Create a folder OpenMC in a drive, where you have write permission, and extract the cross sections data in it.

Example:

D:\OpenMC\endf-b-vii.1-hdf5\

Step 3 – Install OpenMC Windows

Download openmc-windows-v0.1-beta-installer.exe from the release page and execute the installer.

The installer will:

• Install the native OpenMC executable
• Install required runtime libraries
• Add OpenMC to the Windows PATH
• Configure the OPENMC_CROSS_SECTIONS environment variable
• Install the OpenMC Python module (if pip is available)

When prompted, select the folder containing: cross_sections.xml

Select D:\OpenMC\endf-b-vii.1-hdf5\

The installer automatically configures: OPENMC_CROSS_SECTIONS=D:\OpenMC\endf-b-vii.1-hdf5\cross_sections.xml

Step 4 – Verify Installation

Signout and Signin back to your windows account. This will add new directory to the system PATH variable.

Open a new Command Prompt (Win+R, type cmd, Enter):

openmc --version

Expected output:

OpenMC version 0.15.3
Commit hash: 27e38e894697bb32a1dac7848d2618818b6b8daf
Copyright (c) 2011-2025 MIT, UChicago Argonne LLC, and contributors
MIT/X license at <https://docs.openmc.org/en/latest/license.html>
Build type:            Release
Compiler ID:           GNU 15.2.0
MPI enabled:           no
Parallel HDF5 enabled: no
PNG support:           yes
DAGMC support:         no
libMesh support:       no
MCPL support:          no
Coverage testing:      no
Profiling flags:       no
UWUW support:          no

Python API:

python
import openmc
print(openmc.__version__)

Expected output: 0.15.3

Running a Simulation

Copy OpenMC examples to your OpenMC directory

Copy C:\Program Files (x86)\OpenMC\examples to D:\OpenMC directory.

cd D:\OpenMC\examples\jezbel\

python jezbel.py

OpenMC Should be running at this point. Congratulations.

Important Notes

• Native Windows build (WSL or DOCKER is not required to run).
• Compatible with the OpenMC Python API.
• Uses the official OpenMC HDF5 nuclear data library.
• Work in progress to build stable OpenMC GUI

Troubleshooting

1. 'openmc' is not recognized
   • Restart Command Prompt.
   • Verify OpenMC installation directory is in PATH.
2. Python module installation failed
   • Run: python -m pip install openmc
3. OPENMC_CROSS_SECTIONS is not set
   • Check: echo %OPENMC_CROSS_SECTIONS%
   • If empty, create the environment variable manually.
4. Missing DLL errors
   • Ensure all DLLs remain in the same directory as openmc.exe.