基于LoongSARAX的EBR-Ⅱ堆芯精细核子密度模型对中子物理特性的影响  

Influence of fine nuclide density model on neutronic characteristics in EBR-II core based on LoongSARAX

作　　者：李梓康 罗池旭 张滕飞 LI Zikang;LUO Chixu;ZHANG Tengfei(Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学,上海200240

出　　处：《核技术》2025年第2期173-180,共8页Nuclear Techniques

基　　金：国家自然科学基金(No.12175138);上海市青年科技启明星项目;中核集团领创科研项目资助。

摘　　要：EBR-Ⅱ基准题是重要的钠冷快堆中子物理基准题,提供了复杂的堆芯布置和燃料核子密度空间分布,由于其精细数值模型的建模难度和计算代价较大,因此常采用核子密度按组件类型打混的方法建立简化模型。本研究使用LoongSARAX程序分别建立EBR-Ⅱ基准题的精细模型和简化模型,评估简化模型与精细模型在中子物理特性之间的偏差。研究结果显示,相比于精细模型,简化模型的计算耗时降低至十分之一,堆芯有效增殖因子偏低1.383×10^(-2),中子通量密度分布偏平缓,最大相对误差为4.25%。据此可知,虽然核子密度按组件类型打混的简化方法能够降低建模难度和计算成本,但堆芯中子物理特性与精细模型的偏差显著,采用精细模型仍然具有必要性。[Background]Solving benchmark problems is a significant step in the validation of numerical simulation programs.The Experimental Breeder Reactor II(EBR-II)is a famous benchmark for sodium-cooled fast reactors(SFR),with a complicated core configuration and spatial distribution of nuclide density,hence the modeling difficulty and computational cost of its fine numerical models are relatively high.Therefore,simplified model that mixing the spatial distribution of nuclide density by the component type is adopted in many studies on EBR-II benchmark calculation.[Purpose]This study aims to contrast the difference between the results of the fine model and the simplified model,evaluating the rationality of the simplification.[Methods]In this study,both the fine model and the simplified one were built using LoongSARAX,a neutronic numerical program for fast reactors developed by Xi'an Jiao Tong University.Some approximations were applied to these two models,i.e.,one-dimensional homogenization adopted for the half-worth driver assembly to handle its complex radial geometry and the super-assembly method adopted in the cross-section generation of poison elements.Finally,deviation between neutron physical properties in two models was evaluated in terms of computation time consumption,effective multiplication factor,neutron flux density distribution.[Results]The evaluation results show that the spatial distribution of fuel nuclide density presents strong asymmetry and strong non-uniformity in the simplified model,and calculation time spent in the simplified model is one-tenth of that in the fine model.Compared with the fine model,the effective multiplication factor(keff)is 1.383×10^(-2) lower than in the fine model and the spatial distribution of neutron flux is lower in the center and higher in the outer core whereas the maximum relative deviation between neutron flux in two models is 4.25%.[Conclusions]This study demonstrates that the simplified model has a much lower calculation cost but limited numerical accuracy in keff an

关 键 词：钠冷快堆 LoongSARAX EBR-Ⅱ基准题 核子密度分布 

分 类 号：TL433[核科学技术—核技术及应用]