一种利用迹线计算液态核燃料中缓发中子先驱核的新方法
A new calculation method using pathlines for delayed neutron precursors in liquid nuclear fuels
AI总结：
本文提出基于特征线与全域迹线追踪的液态核燃料DNPs浓度计算方法，可在阶跃或分段线性速度场下处理以平流为主的问题，并经基准稳态算例验证。
摘要：
在核反应堆中，缓发中子先驱核（DNPs）对反应堆安全与运行十分重要。在液态核燃料中，DNPs随流体输运，因此除中子平衡方程外，还必须求解其浓度的平流-反应平衡方程。本研究论文应用特征线法求解DNPs方程，采用了此前在石油工程和地下水分析中发展的技术。该计算策略包含一个迹线生成算法，覆盖几何结构中的所有网格单元以进行浓度计算，并针对阶跃速度场和分段线性速度场重构迹线。在笛卡尔网格上使用解析解，并假设DNPs源为阶跃源，以计算DNPs浓度。在一个基准问题的稳态阶段获得的结果，阐明了这种新方法求解液态燃料反应堆中以平流为主问题的能力。本文开发的方法适用于可追踪迹线且DNP扩散率可忽略的平滑速度场（例如层流或RANS流动）。
英文摘要：
In nuclear reactors, Delayed Neutron Precursors (DNPs) are important for reactor safety and operation. In liquid nuclear fuels, DNPs are transported by the flow, and an advection-reaction balance equation for their concentration must be solved in addition to the Neutron Balance Equation. This research paper applies the method of characteristics to solve the DNPs equation, using techniques previously developed in petroleum engineering and groundwater analysis. The calculation strategy incorporates a pathline generation algorithm covering all the mesh cells of the geometry for concentration calculations, and pathlines are reconstructed for both step and piecewise linear velocity fields. The analytical solutions are used on a Cartesian mesh to compute the DNPs concentrations assuming a step source of DNPs. The results obtained on the steady state phases of a benchmark problem illustrate this new method's capability to solve advection-dominated problems in liquid-fueled reactors. The method developed in this work is suited to smooth velocity fields (e.g., laminar or RANS flows) where pathlines can be tracked, and where DNP diffusivity is negligible.
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