Improved solid decomposition algorithms for the CAD-to-MC conversion tool McCad

Highlights: • Creating a model for Monte Carlo simulation is a tough task, especially a model with complicate geometry. • McCad supplies a solution to create the model automatically from CAD model. • Two significant functions included by McCad are solid decomposition and void filling. • The former version of McCad is weak in the decomposition function. • New algorithms are applied for improving the stability and efficiency of the decomposition function. • The improved function has been validated with some example models and EU-DEMO model. • The improved McCad could be applied as an efficient modeling tool for Monte Carlo neutronics simulation. - Abstract: McCad is a geometry conversion tool developed at the Karlsruhe Institute of Technology (KIT) for the automatic conversion of CAD models into the semi-algebraic geometry representations which can then be used in Monte Carlo (MC) particle transport simulations applied in design analyses of fusion and fission reactors. New algorithms for the decomposition of complex geometry models have been designed and implemented in the McCad code. With these improvements, a weakness of the original McCad was mitigated which is due to the instability of the applied graphic kernel and the original decomposition algorithm. The improvements have been verified with some representative test models and a generic model of a DEMO fusion power reactor. The results show that the advanced McCad version with the new decomposition algorithms is more robust and provides more accurate and less complex conversion results. The decomposition process is efficient and produces correct results which are consistent with the original model.