In other words the user provides the problem geometry in a BRL-CAD geometry database file and the MCNP problem parameters (material declarations, source and tally definitions, variance reduction parameters, etc.) in an MCNP-BRL input file. The problem is initialized on the BRL-CAD geometry model, and the ray tracing required by Monte Carlo transport is accomplished through the BRL-CAD API. In MCNP-BRL execution the first two sections of the MCNP input (cell and surface declarations) are skipped, and a BRL-CAD geometry file is provided in their place. The BRL-CAD model of this armored vehicle consists of many complicated regions, and this model can be used by MCNP-BRL directly (i.e., without modifications to the BRL-CAD model). A sample BRL-CAD geometry is depicted in Fig. The BRL-CAD package was chosen as a geometry processor for this application because of its many attractive features: (1) it provides efficient ray-tracing machinery that can be used directly by MCNP (2) it can read a wide variety of industry-standard CAD formats (3) it is actively developed and supported (4) it provides its own powerful geometry editor, MGED, which enables users to develop geometries without recourse to an expensive CAD application and (5) it is open source, so it is available freely to all potential MCNP-BRL users.
Brl cad examples code#
The details of the linkage and the structure of the code package are described in Ref. After testing the feasibility of the GIFT library with a simple geometry package, it was connected to the BRL-CAD code package. By defining the GIFT programming interface, the geometry descriptions in MCNP were replaced with an independent package that performs the setup and ray tracing for Monte Carlo transport. The objective of the work discussed in this paper was to rectify this deficiency by integrating MCNP with a more powerful geometrical processor. Instead, complex CAD geometries are converted into MCNP geometrical constructs at great cost and subject to a high degree of error.
Thus, no integrated tool exists for users wishing to run MCNP on existing engineering blueprints or designs. Moreover, there is no direct linkage between common CAD-based engineering formats and MCNP-style geometric descriptions. The representation of geometric cells using this type of approach can be very tedious and is not possible for extremely complex geometries.
The physical problem geometry in MCNP is defined by the user through specification of surfaces and volumetric cells, which are formed from the intersections and unions of the surfaces. MCNP5 (hereafter referred to simply as MCNP) is a widely used Monte Carlo transport code that was developed at Los Alamos National Laboratory. In addition, performance of the new code and its limitations are discussed. In this summary BRL-CAD implementation of the GIFT library in MCNP5 and the main features of MCNP- BRL are introduced. an extended computer-aided design (CAD) geometry-driven version of MCNP5, was developed by linking MCNP5 to the BRL-CAD via a new geometry interface called the Geometry Interface for Transport (GIFT) library Application Programming Interface (API).
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