Reduced-Order Modelling Applied to the Multigroup Neutron Diffusion Equation Using a Nonlinear Interpolation Method for Control-Rod Movement
Reduced-Order Modelling Applied to the Multigroup Neutron Diffusion Equation Using a Nonlinear Interpolation Method for Control-Rod Movement
复制标题
DOI：
10.3390/en14051350
复制
发表时间：
2021-03
期刊：
影响因子：
3.2
通讯作者：
C. Heaney;A. Buchan;C. Pain;S. Jewer
中科院分区：
文献类型：
--
作者：
C. Heaney;A. Buchan;C. Pain;S. Jewer
产生反应堆中中子扩散的高保真实时模拟在计算上极具挑战性，部分原因是能量和空间的多尺度行为。在许多科学领域，包括核建模，降阶建模的应用可以导致更快的计算时间，而不会损失太多的准确性，为实时模拟以及多查询问题，如不确定性量化和数据同化铺平了道路。本文比较了两个降阶模型，适用于模拟控制棒在燃料组件中的运动，对于一个给定的温度分布。第一个是一个标准的方法，使用适当的正交分解（POD）生成全局基函数，和第二个，一种新的方法，使用POD，但产生的全局基函数是本地的参数空间（与控制棒高度）。近似的特征值问题，在减少的空间，一种新的，非线性插值提出了控制棒高度的建模依赖。可以看出，这两种方法的预测精度提高了两个数量级的keff和一个数量级的标量通量看不见的参数值。
Producing high-fidelity real-time simulations of neutron diffusion in a reactor is computationally extremely challenging, due, in part, to multiscale behaviour in energy and space. In many scientific fields, including nuclear modelling, the application of reduced-order modelling can lead to much faster computation times without much loss of accuracy, paving the way for real-time simulation as well as multi-query problems such as uncertainty quantification and data assimilation. This paper compares two reduced-order models that are applied to model the movement of control rods in a fuel assembly for a given temperature profile. The first is a standard approach using proper orthogonal decomposition (POD) to generate global basis functions, and the second, a new method, uses POD but produces global basis functions that are local in the parameter space (associated with the control-rod height). To approximate the eigenvalue problem in reduced space, a novel, nonlinear interpolation is proposed for modelling dependence on the control-rod height. This is seen to improve the accuracy in the predictions of both methods for unseen parameter values by two orders of magnitude for keff and by one order of magnitude for the scalar flux.