基于蒙特卡罗-离散纵标双向耦合方法的快中子注量基准分析

蒙特卡罗（MC）-离散纵标（S_N）双向耦合方法是解决大型复杂核装置屏蔽问题的有效方法。本文针对三维MC-S_N双向耦合方法在大型压水堆核电站屏蔽计算中的应用，进行了基准验证分析。基于美国核管会（NRC）发布的NUREG/CR-6115压水堆基准模型，采用自主开发的三维MC-S_N双向耦合屏蔽计算分析方法，利用MCNP4C精确计算堆芯到热屏蔽精细模型以及位于压力容器内部计算区域的精确模型，三维S N 程序TORT用于进行热屏蔽到第2下降区外表面间的计算。通过自主研发的接口程序实现MC粒子概率分布与S_N角通量密度间的相互转换，实现MC和S_N 双向耦合计算。三维MC-S_N双向耦合方法计算结果与基准报告提供的MCNP、DORT结果符合良好，初步验证了该方法解决大型复杂核装置屏蔽问题的可行性。

Fast Neutron Fluence Calculation Benchmark Analysis Based on 3D MC S N Bidirectional Coupling Method

The Monte Carlo （MC）-discrete ordinates （S_N） bidirectional coupling method is an efficient approach to solve shielding calculation of the large complex nuclear facility. The test calculation was taken by the application of the MC-S_N bidirectional coupling method on the shielding calculation of the large PWR nuclear facility. Based on the characteristics of NUREG/CR-6115 PWR benchmark model issued by the NRC, 3D Monte Carlo code was employed to accurately simulate the structure from the core to the thermal shield and the dedicated model of the calculation parts locating in the pressure vessel， while the TORT was used for the calculation from the thermal shield to the second down-comer region. The transform between particle probability distribution of MC and angular flux density of S_N was realized by the interface program to achieve the coupling calculation. The calculation results were compared with MCNP and DORT solutions of benchmark report and satisfactory agreements were obtained. The preliminary validity of feasibility by using the method to solve shielding problem of a large complex nuclear device was proved.