DAG-OpenMC在聚变中子学分析中的应用研究

Study on application of DAG-OpenMC in fusion neutronics analysis

聚变装置工程模型极其复杂,使得中子学分析的建模十分繁琐和耗时。开源蒙特卡罗程序OpenMC通过集成DAGMC(Direct Accelerated Geometry Monte Carlo),可以直接基于CAD模型进行粒子输运模拟计算,该特性可显著提高复杂工程模型的建模与分析效率。以中国聚变工程试验堆(China Fusion Engineerging Test Reactor,CFETR)为对象,开展OpenMC在聚变中子学分析中的应用研究。基于CFETR一维柱壳模型验证OpenMC与MCNP计数结果的一致性。根据等离子体空间分布特点,基于源扩展接口自定义源类和源函数准确描述复杂聚变中子源。利用DAG-OpenMC的CAD几何功能成功建立了CFETR的三维模型,并计算获得了中子壁负载分布、氚增殖率和核热沉积等物理量。结果表明:DAG-OpenMC与MCNP的计算结果具有极好的一致性。在建立复杂的聚变堆工程模型时,基于CAD几何功能极大地提高了建模效率。DAG-OpenMC在聚变中子学应用中关键问题的验证表明了其处理复杂工程结构条件下聚变中子学问题的可行性。

[Background]Fusion reactor engineering models are extremely complex,which makes the modeling of the neutronics analysis rather tedious and time consuming.The open-source Monte Carlo code OpenMC can directly perform particle transport simulation on CAD models by integrating DAGMC(Direct Accelerated Geometry Monte Carlo),which can significantly improve the modeling and analysis efficiency of complex engineering models.[Purpose]This study aims to carry out the application research of OpenMC in fusion neutronics analysis for China Fusion Engineering Test Reactor(CFETR).[Methods]Based on the CFETR 1D cylindrical shell model,the consistency of tallies of OpenMC and MCNP was verified.According to the characteristics of plasma spatial distribution,source class and source function were customized on base of the source extension interface to accurately describe the complex fusion neutron source.The 3D model of complex CFETR engineering was successfully established by using CAD geometry function of DAG-OpenMC,and the neutron wall load distribution,tritium breeding ratio(TBR)and heat were obtained.[Results]The calculation results of DAG-OpenMC and MCNP have excellent consistency. The neutron wall load peak of CFETR appears at the mid plane, and the tritium breeding ratio of helium cooled ceramic breeder blanket is 1.141. When the fusion neutron power is 160 MW, the total nuclear heat generated is 211.73 MW, and the global energy multiplication factor is 1.32, in which the total nuclear heat generated by the blanket is 185.64 MW, accounting for 87.68% of the total nuclear heat. [Conclusions] The CAD-based geometry capabilities greatly improve the modeling efficiency of building complex fusion reactor engineering models. Verification of the key issues of DAG-OpenMC in fusion neutronics applications by this study, indicates its feasibility in dealing with fusion neutronics problems under complex engineering structural conditions.