Application of global variance reduction method to calculate a high-resolution fast neutron flux distribution for TMSR-SF1
Application of global variance reduction method to calculate a high-resolution fast neutron flux distribution for TMSR-SF1
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应用全局方差约简法计算TMSR-SF1高分辨率快中子通量分布
DOI：
10.1007/s41365-019-0650-y
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发表时间：
2019
影响因子：
2.8
通讯作者：
Yuwen Ma
中科院分区：
文献类型：
--
作者：
Pu Yang;Ye Dai;Y. Zou;Rui Yan;Bo Zhou;Shihe Yu;Yuwen Ma
固体燃料钍熔盐堆（TMSR-SF 1）是一座10 MWth的氟化物冷却球床堆。作为一种新的反应堆概念，反应堆寿命的主要限制因素之一是辐射引起的材料损伤。快中子通量（E> 0.1 MeV）可用于评估可能的辐射损伤。因此，需要一种计算全尺寸TMSR-SF 1反应堆快中子注量率分布的高分辨率方法。在这项研究中，一个两步的分段方法的基础上MCNP 5涉及一个整体的方差减少的方法，被称为前向加权一致伴随驱动的重要性抽样，实现了整个TMSR-SF 1设施的快中子通量分布。此外，在MCNP 5源代码中，利用用户提供的SOURCE子程序实现了一种专门针对TMSR-SF 1的源偏置技术，而不是使用通用的源规范卡。与一步模拟方法相比，两步分段方法消除了零分网格计数单元，并获得了非常均匀且相对不确定性低的计数结果。此外，还提供了TMSR-SF 1中主要组分的最大快中子注量率，可用于结构材料的辐射损伤评估。
The solid fuel thorium molten salt reactor (TMSR-SF1) is a 10-MWth fluoride-cooled pebble bed reactor. As a new reactor concept, one of the major limiting factors to reactor lifetime is radiation-induced material damage. The fast neutron flux (E> 0.1 MeV) can be used to assess possible radiation damage. Hence, a method for calculating high-resolution fast neutron flux distribution of the full-scale TMSR-SF1 reactor is required. In this study, a two-step subsection approach based on MCNP5 involving a global variance reduction method, referred to as forward-weighted consistent adjoint-driven importance sampling, was implemented to provide fast neutron flux distribution throughout the TMSR-SF1 facility. In addition, instead of using the general source specification cards, the user-provided SOURCE subroutine in MCNP5 source code was employed to implement a source biasing technique specialized for TMSR-SF1. In contrast to the one-step analog approach, the two-step subsection approach eliminates zero-scored mesh tally cells and obtains tally results with extremely uniform and low relative uncertainties. Furthermore, the maximum fast neutron fluxes of the main components in TMSR-SF1 are provided, which can be used for radiation damage assessment of the structural materials.