原子能科学技术2024，Vol.58Issue(3)：654-661,8.DOI:10.7538/yzk.2023.youxian.0358
三维球床几何稀疏条数长特征线加速方法
Sparse Macro-track Transport Acceleration Method for 3-D Pebble-bed Geometry
摘要
Abstract
The method of characteristics has very strong geometric adaptability and can be used to solve the 3-D whole core problem of high temperature gas-cooled pebble-bed reactor.However,it suffers from the disadvantages of thousands of iterations and slow calculation speed.At present,there have been some attempts to reduce calculation time for method of characteristics,including coarse mesh finite difference(CMFD),general coarse mesh rebalance(GCMR)and general coarse mesh finite difference(GCMFD).The CMFD method is applied to realize the acceleration of regular region like squares.Furthermore,to break through the limitation of macroscopic regular geometry for the numerical acceleration method,researchers successively propose the GCMR method and the GCMFD method,but these methods are very complex to implement in irregular geometries and some approximation factors must be introduced.Based on the analysis of more dense tracks are arranged for the 3-D model,the sparse macro-track transport acceleration method was proposed,which greatly reduces the calculation amount of the acceleration equation and obtains a very good acceleration efficiency without reducing the accuracy.The 2-D method of characteristics divides the angular space into M azimuthal angles and P pole angles.The 3-D method of characteristics generally uses a level sym-metric quadrature set.In 2-D geometry,the angle is relatively more dense at the poles.As a result,the 2-D macro-track transport acceleration can select a small number of azimuth angles with reflection symmetry and one pole angle as the solution directions of the acceleration equation.The sparse macro-track transport acceleration method imple-mented in this paper used the same angles as the method of characteristics.The number of tracks for 3-D problems is an order of magnitude higher than for 2-D problems.That is why reducing the number of 3-D tracks is a promising method for reducing the amount of accelerated equation calculation.This paper applied the macro-track transport acceler-ation method to 3-D whole core problem of high temperature gas-cooled pebble-bed reac-tor to solve the problem of irregular geometric numerical acceleration.The sparsity,macro-track length limit,and the maximum iteration step limit of the macro-track meth-od are the main factors that affect the acceleration performance.The selection method of acceleration parameters was studied through two benchmark problems.Excellent speed-up ratio can be obtained by setting the sparsity to 3-5,the macro-track length to around 2.0 cm,the acceleration iteration steps limit to 20-60.The results of 3-D small light water reactor benchmark and simplified pebble-bed reactor core model show that about 7 times the time speedup ratio and about corresponding 20 times the iterative step speed-up ratio can be achieved.关键词
球床高温气冷堆/特征线法/长特征线加速方法/中子输运Key words
high temperature gas-cooled pebble-bed reactor/method of characteristics/macro-track transport acceleration method/neutron transport分类
能源科技引用本文复制引用
郭建,郭炯,李富,严睿,邹杨..三维球床几何稀疏条数长特征线加速方法[J].原子能科学技术,2024,58(3):654-661,8.基金项目
中国科学院引才计划青年项目(SINAP-YCJH-202303) （SINAP-YCJH-202303）
中国科学院战略性先导科技专项(XDA02010000) （XDA02010000）
中国科学院前沿科学重点研究(QYZDY-SSW-JSC016) （QYZDY-SSW-JSC016）
国家自然科学基金(12005290) （12005290）
