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Comparison · Analytics
OpenMC vs iris
A side-by-side editorial comparison of OpenMC and iris — release velocity, themes, recent moves, and the top alternatives to consider.
OpenMC vs iris: at a glance
What is OpenMC?
OpenMC's random ray solver has gone from new arrival to the centre of every release
OpenMC is a Monte Carlo particle transport code for neutronics and radiation analysis. Since the random ray transport solver landed in 0.15.0 it has received substantial work in every subsequent release, most recently local adjoint sources, temperature and distributed-density feedback, fission-heating tallies and a weight-window bootstrapping workflow. The other consistent thread is shutdown-dose and depletion tooling, where 0.15.3 introduced an R2SManager to automate the rigorous two-step workflow and 0.16.0 extended it with reactivity control, CRAM substeps and multiple meshes.
What is iris?
Iris ships steadily on a two-a-year cadence, but its feed publishes only pointers.
Iris tags a release candidate roughly every four to five months — 3.13 through 3.16 over the past year — and the cadence is the only thing the feed actually reports. Every entry is the same seven-line template: a line saying this is a release candidate, conda-forge and PyPI install commands, and a link to a 'What's New' page held elsewhere. No release notes reach the feed at all.
OpenMC vs iris: editorial side-by-side
OpenMC
2.5ANALYTICS
OpenMC's random ray solver has gone from new arrival to the centre of every release
◆ Current state
OpenMC is a Monte Carlo particle transport code for neutronics and radiation analysis. Since the random ray transport solver landed in 0.15.0 it has received substantial work in every subsequent release, most recently local adjoint sources, temperature and distributed-density feedback, fission-heating tallies and a weight-window bootstrapping workflow. The other consistent thread is shutdown-dose and depletion tooling, where 0.15.3 introduced an R2SManager to automate the rigorous two-step workflow and 0.16.0 extended it with reactivity control, CRAM substeps and multiple meshes.
◆ Where it's heading
The project is layering a deterministic-adjacent solver alongside its Monte Carlo core rather than replacing it, and the ratio of random-ray work to core-solver work in each release keeps rising. In parallel it is packaging expert workflows into objects — R2SManager is the clearest case, turning a multi-stage shutdown dose calculation into a class rather than a recipe. The Python API is where most of that packaging surfaces, and it is also where the compatibility breaks land, with the minimum version moving to 3.12 in 0.16.0.
◆ Prediction
Given that every release since 0.15.0 has expanded the random ray solver's feedback and tally coverage, the next is likely to continue closing the gap between it and the main solver's feature set. The notes do not indicate whether it is intended to become a default path.
iris
2.5ANALYTICS
Iris ships steadily on a two-a-year cadence, but its feed publishes only pointers.
◆ Current state
Iris tags a release candidate roughly every four to five months — 3.13 through 3.16 over the past year — and the cadence is the only thing the feed actually reports. Every entry is the same seven-line template: a line saying this is a release candidate, conda-forge and PyPI install commands, and a link to a 'What's New' page held elsewhere. No release notes reach the feed at all.
◆ Where it's heading
The version numbers say a mature Met Office library is being maintained on a predictable schedule; nothing in the published entries says what is being maintained. Until the project puts release content in the tag body, its public trail will read as cadence without substance, and readers have to leave the feed to learn anything. The pattern has been identical across four consecutive releases, so it is a deliberate publishing choice rather than an oversight.
◆ Prediction
Expect v3.17.0rc0 around late 2026 on the same schedule, carrying the same boilerplate — the notes will again live on the documentation site rather than in the release entry.
Alternatives to OpenMC and iris
Other Analytics products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either OpenMC or iris.
modeltime
modeltime built conformal intervals in, then went quiet on features.
performance
performance keeps adding ways to check a model you have already fitted.
cmdstanpy
CmdStanPy is clearing deprecations ahead of a 2.0 it keeps announcing.
dowhy
DoWhy adds one estimation method a year and keeps its identification edge.
OpenHouse
OpenHouse is hardening the seams where table policies and jobs quietly fail.
Recent activity from OpenMC and iris
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 6d agoOpenMCSurface-flux tallies and PDG particle identifiers in OpenMC 0.16.0
- 13d agoirisv3.16.0rc0
- 4mo agoirisv3.15.0rc0
- 8mo agoOpenMCR2SManager automates shutdown dose rate calculations in OpenMC 0.15.3
- 9mo agoirisv3.14.0rc0
- 1y agoirisv3.13.0rc0
- 1y agoOpenMCOpenMC 0.15.2 hotfixes an MPI regression
- 1y agoOpenMCRay-traced material volumes and Phong-shaded plots in OpenMC 0.15.1
- 2y agoOpenMCOpenMC 0.15.0 introduces a random ray transport solver ⚡
- 2y agoOpenMCWeight window generation and continuous nuclide feed in OpenMC 0.14.0
Frequently asked questions
What is the difference between OpenMC and iris?
They serve adjacent needs but don't currently overlap on shipped themes. OpenMC and iris are shipping at a similar cadence (velocity 2.5 vs 2.5, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is OpenMC better than iris?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. OpenMC and iris are shipping at a similar cadence (velocity 2.5 vs 2.5, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other Analytics products to evaluate alongside.
What are the best alternatives to OpenMC?
Top OpenMC alternatives in Analytics are ranked by recent ship velocity. Browse the "OpenMC alternatives" section above for the current picks, or visit /alternatives/openmc for the full list with editorial commentary on each.
What are the best alternatives to iris?
Top iris alternatives in Analytics are ranked by recent ship velocity. Browse the "iris alternatives" section above for the current picks, or visit /alternatives/scitools-iris for the full list with editorial commentary on each.