中文摘要：

特征线方法（Method of Characteristics，MOC）能否应用于复杂几何关键在于能否将特征线方法与有效的几何处理方法结合起来。本文在菱形差分特征线理论基础上，基于FDS团队自主研发的核与辐射输运计算自动建模软件MCAM的几何处理引擎，研发了基于CAD技术的特征线中子输运计算程序，并利用相关基准例题对程序进行了数值验证，其结果与参考值吻合良好，表明本文方法和程序的可行性、正确性与可靠性。

英文摘要：

The main problem determining whether the method of characteristics （MOC） can be used in complicated and highly heterogeneous geometry is how to combine an effective geometry processing method with MOC. In this study, a new idea making use of MCAM, which is a Mutlti-Calculation Automatic Modeling for Neutronics and Radiation Transport program developed by FDS Team, for geometry description and ray tracing of particle transport was brought forward to solve the geometry problem mentioned above. Based on the theory and approach as the foregoing statement, a two dimensional neutron transport code was developed which had been integrated into VisualBUS, developed by FDS Team. Several benchmarks were used to verify the validity of the code and the numerical results were coincident with the reference values very well,which indicated the accruracy and feasibility of the method and the MOC code.