Abstract cosRMC is a three dimensional neutron photon transport Monte Carlo code based on the stochastic statistical method of neutral particle transport. At present, the cosRMC geometry model is imported by writing the input file manually, which leads to time-consuming, inefficient and error-prone problems. This will limit application of cosRMC in fusion neutronics calculations because of the complex geometry in fusion devices. Therefore, in order to improve the modeling efficiency and meet the requirements of calculation and analysis of advanced nuclear facilities, a visual modeling platform, cosVMPT—Visual Modeling Platform for Particle Transport, is developed based on Open Cascade (OCC) as CAD geometry engine and FreeCAD framework as graphical user interface. This platform can realize the complete process from modeling to calculation, then to visualization. In this article, the conversion algorithm from CAD models to cosRMC geometry models is introduced in detail. The reliability of the conversion algorithm is preliminarily verified with some representative models by comparing volumes change before and after conversion. The result shows that the geometries after conversion are in good consistency with the original geometries.

中文翻译：

---

开发用于 CAD 到 cosRMC 建模的辅助程序

摘要 cosRMC是一种基于中性粒子输运随机统计方法的三维中子光子输运蒙特卡罗编码。目前cosRMC几何模型是通过手工编写输入文件的方式导入的，存在耗时、低效、容易出错的问题。由于聚变装置中的复杂几何形状，这将限制 cosRMC 在聚变中子学计算中的应用。因此，为了提高建模效率，满足先进核设施计算分析的要求，基于Open Cascade（OCC）作为CAD几何引擎，开发了可视化建模平台cosVMPT——粒子输运可视化建模平台。 FreeCAD 框架作为图形用户界面。该平台可以实现从建模到计算的完整流程，然后到可视化。本文详细介绍了CAD模型到cosRMC几何模型的转换算法。通过比较转换前后的体积变化，用一些具有代表性的模型初步验证了转换算法的可靠性。结果表明，转换后的几何图形与原始几何图形具有良好的一致性。