OpenMC — The Complete Guide: Free Monte Carlo Neutron Transport for Nuclear Engineering
OpenMC is an open-source Monte Carlo code for neutron and photon transport, started at MIT and developed today also at Argonne National Laboratory. It is used in nuclear engineering for criticality, neutron flux, fuel depletion and radiation shielding — a field where the traditional codes were until recently restricted by licensing and export control.
OpenMC
MIT / Argonne National Laboratory
Monte Carlo neutron transport — criticality, fuel depletion and radiation shielding, Python-driven.
Get it from the vendorWhat you get
- Criticality — the multiplication factor of a reactor or fissile arrangement.
- Tallies — flux, reaction rates and heating in any region and energy range.
- Depletion — tracking fuel composition over operating time.
- Geometry — built-in constructive solid geometry, with an option for CAD geometry.
- Parallelism — MPI and OpenMP, from a laptop to a supercomputer.
How to use it
The whole model — materials, geometry, settings and tallies — is written in Python, so parametric studies and automation are relatively simple. You need to download a standard cross-section library in the format the code uses. It runs on Linux and macOS; on Windows use WSL or Docker.
Related tools
To view flux fields and 3D results — ParaView. For coupled multiphysics, for example with thermal hydraulics — MOOSE. For data analysis and plots — JupyterLab.
ParaView
Kitware / Sandia / Los Alamos
Large-scale simulation post-processing — slices, streamlines and animation.
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MOOSE Framework
Idaho National Laboratory
A multi-physics finite-element framework from Idaho National Laboratory.
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JupyterLab
Project Jupyter
Interactive computing notebooks — code, results, plots and explanations in one shareable document.
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Python
Python Software Foundation
The language behind most modern engineering computation, and its full ecosystem.
Get it from the vendorThe bottom line
OpenMC is the open, modern alternative to nuclear Monte Carlo codes — completely free, with an active community and good documentation.