Introduction

Tamarack is a geometry visualization and workflow tool designed to operate directly on MCNP input decks. It preserves MCNP’s trusted text-based representation while providing explicit, interactive 3D insight into implicit CSG geometry.

Supported MCNP Versions

Tamarack supports MCNP6 and later variants that adhere to standard surface and cell card definitions.

MCNP Geometry Model

MCNP geometry is defined implicitly through Boolean combinations of surfaces assigned to cells. Tamarack reconstructs this geometry by parsing surface definitions and evaluating cell logic exactly as MCNP interprets it.

Example Cell Definition

1  1  -7.85  -1  2  -3  imp:n=1
2  0           1:-2:3  imp:n=0
    

Tamarack identifies surface references, evaluates Boolean operators, and constructs a closed 3D representation for visualization and validation.

CAD Import Workflow

Tamarack supports importing CAD geometry as a starting point for MCNP modeling. Imported solids are decomposed into MCNP-compatible surfaces and cells.

Supported Formats

• STEP (.stp, .step)
• IGES (.igs)
• Parasolid (.x_t)

Exporting Geometry

Tamarack can export MCNP geometry to standard 3D formats for review, documentation, or collaboration.

Known Limitations

Certain MCNP features—such as advanced lattice constructs or highly degenerate surface intersections—may have visualization limitations. These do not affect MCNP execution.