MCNP2CAD README

MCNP to iGeom/CAD converter: a program to extract the geomtery from MCNP input files and write it out using any ITAPS iGeom backend.

This project creates a shared object file which is called by the Trelis plugin or the command line interface created with the -DBUILD_CLI=true flag.

The following groups intend to support such implementations:

• CNERG will develop an iGeom-like interface as part of a Trelis & Cubit plugin that uses this library to import MCNP geometry into Trelis/Cubit.
• The SIGMA team will develop an iGeom-like interface as part of an implementation of CGM that is based on the OpenCascade solid modeling engine. This version may support a command line tool.

Bug reports are appreciated - please post an issue in our Github repository.

This tool is based on an concept first developed at Argonne National Laboratory.

Build Instructions:

Using cmake:

Install Eigen3.

When installing mcnp2cad, be sure to include the following flags:

-DIGEOM_LIB_DIR= path to directory containing libigeom

-DIGEOM_INCLUDE_DIR= path to iGeom include directory

If building the command line interface, also include the following flag:

-DBUILD_CLI=yes

Unsupported Features:

• Could be added easily:

  • More direct control over the size of the sphere/graveyard in which the geometry sits
  • Support for interpolation (nI/nILOG) and multiplication (nM) syntax.
  • Make the title card optional, as it apparently is in MCNP.

• Could be added with effort:

  • Correct handling of hexagonal prism lattices for lattices based on irregular hexgons
  • Support for ELL (ellipse), WED (wedge), and ARB (arbitrary polyhedron) macrobodies
  • Ability to refer to individual facets of macrobodies as surfaces in cell specification, using the NNNN.MM syntax. Parsing support for this feature exists, but output support does not.
  • Support for lattices in universe 0
  • Faster/more efficient generation of embedded universes within lattices.
  • Complete support for M=-1 argument in TRn (transform) cards.
  • Automatically annotate reflecting/white boundaries and periodic surfaces.
  • Support for 3-arg and 5-arg specification of rotations in transformations.
  • Support for jump (nJ) syntax: requires knowledge of default values in many possible contexts

• Could be added with substantial effort:

  • General support for SQ, GQ, X, Y, and Z surfaces. (Elliptic Cylinders and Elliptic Cones currently supported.) (Simple X, Y, Z surfaces are already supported.)
  • Robust error detection and reporting for ill-formed MCNP inputs.