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 is currently in transition based on changes to the underlying CGM library. The end state of this code will be a library that relies upon an iGeom-like implementation to perform the solid model manipulations. That iGeom-like implementation will be supported by other groups.

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.

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.