The software development division of ReactorMC

BELVOIR DYNAMICS

Software for nuclear Monte Carlo

GROVES, OWEN, and NICHOLS — three surfaces on one shared stack of grammars, validators, and reference data for MCNP, OpenMC, Serpent, and SCONE.

Built for air-gapped labs, IDE workflows, and lightweight editors — no telemetry.

Cross-code converter 3D geometry preview

Product line

GROVES

v1.3.7

Windows desktop

Desktop Reactor Input Editor

Air-gap-friendly PySide6 editor with BEAVRS 3D preview, cross-code converter, results viewer, PNNL materials, and embedded ALLEN. No toolchain to manage, no network calls.

  • ·Fully offline — no telemetry, works on isolated networks
  • ·Hi-fi MCNP↔OpenMC converter + OpenMC geometry verify
  • ·Lattice builder, templates, deep validation for all four codes
Download installerProduct page

OWEN

v1.0.2

VS Code & Cursor

VS Code Extension

Language server, cross-code converter (MCNP↔OpenMC stable), native OpenMC render/verify, ALLEN Doppler Studio, 3D preview, and results dashboards — inside your IDE.

  • ·Convert Deck… with Rosetta diff webview
  • ·Go-to-definition, find-references & real-time diagnostics
  • ·Published on the VS Code Marketplace and Open VSX
Install from MarketplaceProduct page

NICHOLS

v1.0.0

Sublime Text & Notepad++

Lightweight Editor Packages

OWEN's grammars, snippets, and color schemes ported to Sublime Text and Notepad++ — the only package covering all four Monte Carlo codes in both editors.

  • ·Sublime: syntaxes, completions, build systems, 80-col ruler
  • ·Notepad++: UDLs with folding, auto-completion, API hints
  • ·Static configs — nothing to run, nothing phones home
Download packagesProduct page

Browser demos

Try before you install

Client-side on reactormc.net — same parsers as OWEN and GROVES, no upload, no account.

OWEN & GROVES

Cross-code deck converter

MCNP ↔ OpenMC — stableMCNP → Serpent / SCONE — experimental

Port reactor geometry, materials, lattices, and criticality settings between codes — without hand-rewriting every card. Run MCNP→OpenMC in the browser or Convert Deck… in the IDE for the full Rosetta diff.

Open live converter

OWEN & GROVES

3D geometry preview

MCNP · OpenMC · Serpent · SCONE

Paste a pin cell or lattice deck and inspect fuel, clad, and moderator layers — orbit controls, slice planes, layer toggles, and a fullscreen viewport.

Open geometry preview

One knowledge base, three surfaces

Every product draws on the same grammars, validators, and reference data. What ships where:

CapabilityGROVESOWENNICHOLS
Cross-code deck converter (MCNP↔OpenMC stable)
Syntax highlighting — MCNP, OpenMC, Serpent, SCONE
Completions & snippets
4-palette color schemes
MCNP 80-column guard
Deep deck validation & diagnostics
MCNP cross-reference tracker (go-to-def, references)
Visual lattice builder
3D geometry preview (BEAVRS radial structure)
ALLEN σ(E) cross-section viewer
Results viewer & parametric sweep dashboard
Prebuilt BEAVRS models
Run simulations from the editor
Fully offline / air-gap friendly

Deployment guidance

Pick GROVES if…

You need a fully-offline standalone editor for air-gapped or export-controlled workflows, with a built-in 3D viewer and no Python toolchain to manage.

Pick OWEN if…

You already work in VS Code or Cursor and want diagnostics, cross-references, and the lattice builder inline with the rest of your project.

Pick NICHOLS if…

You live in Sublime Text or Notepad++ and want proper highlighting and completions for your decks without changing editors.

Products coexist — many programs run OWEN at the desk and GROVES on the isolated network. Cross-code converter guide →

BELVOIR DYNAMICS

Built for programs that cannot afford input errors

BelvoirDynamics removes the friction every Monte Carlo engineer knows — the wrong density sign, a mismatched ZAID temperature suffix, a hand-laid 17×17 lattice — in the editor, before the code ever runs.

Shared knowledge

The same grammars, validators, NRDP material library, and lattice generators feed all products.

Independent releases

OWEN on the VS Code Marketplace and Open VSX; GROVES as a signed Windows installer; NICHOLS as zip packages on GitHub Releases.

No telemetry

No product collects analytics or transmits input files. Verify SHA-256 checksums on each release page.

BelvoirDynamics releases

caalh/BelvoirDynamics-releases — signed Windows installers with SHA-256 checksums