六角形组件压水堆环境效应处理方法研究

Study on Treatment Method of Environmental Effect of Hexagonal Assembly PWR

针对六角形组件压水堆,提出一种改进多组件均匀化方法,以降低燃料组件环境效应对两步法计算精度的影响,并从燃耗深度这一状态变量出发,开展了敏感性分析,拓展了该方法的实用性。该方法通过构建多组件模型近似获取毗邻反射层燃料组件的真实堆芯能谱,采用非均匀修正因子减少由于环境效应对单组件全反射边界模型少群常数计算的偏差,同时仅对传统两步法计算策略进行微调,对整体程序框架影响较小。计算结果表明,该方法可有效改善传统两步法的计算精度,特征值偏差由-341pcm(1pcm=10^(-5))降低至-111pcm,组件功率均方根偏差也由2.28%减小到1.38%。

An improved multi-assembly homogenization method is raised to deal with the environmental effect of the hexagonal fuel assembly in PWRs.In order to reduce the influence of environmental effect of fuel assembly on the calculation accuracy of two-step method,sensitivity analysis is carried out from the state variable of burnup depth,which expands the practicability of this method.In this method,the real core energy spectrum of the fuel assembly adjacent to the reflector is approximately obtained by establishing a multi-assembly model,and the heterogeneous correction factor is adopted to reduce the deviation of the calculation of few-group constants of the single-assembly model with reflective boundary due to environmental effects.At the same time,the traditional two-step calculation strategy is fine-tuned,which has little impact on the overall code framework.The calculation results show that this method can effectively improve the calculation accuracy of the traditional two-step method,and the eigenvalue deviation is reduced from-341pcm(1pcm=10^(-5))to-111pcm,and the root mean square deviation of assembly power is also reduced from 2.28%to 1.38%.