基于蒙特卡罗-离散纵标双向耦合方法的三维程序开发

Development of Three-dimensional Program Based on Monte Carlo and Discrete Ordinates Bidirectional Coupling Method

蒙特卡罗方法(MC)和离散纵标方法(SN)是辐射屏蔽设计常用的两种计算方法。蒙特卡罗方法可以精确描述复杂模型,但对于深穿透问题计算耗时;离散纵标方法计算速度较快,但在几何描述方面存在限制,多维计算还存在射线效应。单一的MC或SN方法在大型复杂核装置屏蔽计算中都存在一定限制。为了有效解决大型复杂核设施屏蔽计算问题,本文研究了蒙特卡罗-离散纵标双向耦合方法,通过自主开发的接口程序实现MC粒子概率分布与SN角通量密度之间的相互转换,实现蒙特卡罗和离散纵标方法的耦合计算,充分发挥两种方法的优势。本文进行了直角坐标系和圆柱坐标系下的测试验证,耦合程序计算结果与MCNP、TORT结果吻合良好,初步证明了蒙特卡罗-离散纵标双向耦合程序的正确性。

The Monte Carlo （MC） and discrete ordinates （SN） are the commonly used methods in the design of radiation shielding. Monte Carlo method is able to treat the geometry exactly, but time-consuming in dealing with the deep penetration problem. The discrete ordinate method has great computational efficiency, but it is quite costly in computer memory and it suffers from ray effect. Single discrete ordinates method or single Monte Carlo method has limitation in shielding calculation for large complex nuclear facilities. In order to solve the problem, the Monte Carlo and discrete ordinates bidirectional coupling method is developed. The bidirectional coupling method is implemented in the interface program to transfer the particle probability distribution of MC and angular flux of discrete ordinates. The coupling method combines the advantages of MC and SN. The test problems of cartesian and cylindrical coordinate have been calculated by the coupling methods. The calculation results are performed with comparison to MCNP and TORT and satisfactory agreements are obtained. The correctness of the program is proved.