Experience with Conversion of CAD to Monte Carlo Particle Transport Models

During the past two years a team at Lawrence Livermore National Laboratory (LLNL) has used Raytheon's TopAct code to convert a variety of CAD models into TART and MCNP Monte Carlo input files. TopAct offers the possibility of enormous savings by largely eliminating the need for manual generation of models via combinatorial geometry. Also, TopAct is expected to deliver improvements in quality assurance and configuration management. We detail our experiences with various test problems. The reader will see the steady improvements that have been made in the conversion process and understand our expectations for further progress. Finally, we explain how TopAct will become a cornerstone of our future neutronics efforts.