三维MOC的球床堆芯CMFD加速研究

gCMFD acceleration method for solving a pebble-bed reactor by 3D-MOC

为了解决稀疏长特征线方法在加速效果,特别是降低计算时间上仍存在的不足,本文使用基于广义等价理论的粗网有限差分方法作为三维特征线方法的加速算法,并开发粗网有限差分方法模块用于加速MOCP程序的精细化输运计算。MOCP程序开发三维特征线方法模块针对球床式反应堆进行精细化输运计算,并使用稀疏长特征线方法加速3D-MOC。根据MOCP中构造实体几何建模方法处理球床区域中燃料球细网与粗网的映射关系以保证粗网均匀化参数的准确计算。最后用不同堆型、不同几何模型对粗网有限差分方法加速模块与球床处理模块进行验证,保证粗网与细网严格对应的同时,使3D-MOC整体迭代次数与计算耗时减少约90%。计算结果表明该模块正确且拥有良好的加速效果。

To overcome the shortcomings of the macrotrack transport acceleration(MTTA)method in terms of the acceleration effect,especially in reducing the computation time,the generalized equivalence theory-based coarse-mesh finite difference method(gCMFD)is used as the acceleration method for 3D-MOC to develop a gCMFD module for accelerating the high-fidelity neutron transport calculation of the MOCP program.The three-dimensional method of characteristics(3D-MOC)module developed by the MOCP program is used for the high-fidelity neutron transport calculation of pebble-bed reactors,and MTTA is used to accelerate the 3D-MOC.The mapping relationship between the fine mesh and coarse mesh of the fuel sphere in the pebble-bed region is handled according to the constructive solid geometry modeling method in MOCP to ensure an accurate calculation of the coarse-mesh homogenization parameters.Finally,the gCMFD acceleration module and pebble-bed processing module are validated with different types of rectors and geometry models to ensure a strict correspondence between the coarse mesh and fine mesh while reducing the number of iterations and computation time of 3D-MOC by approximately 90%.The numerical results indicate that this module is correct and has an excellent acceleration effect.