一维平板外源驱动次临界系统动态参数权重函数研究

在准静态框架下,动态参数由权重函数、动力学量算符、形状函数的卷积得到.传统方法的权重函数并不能满足外源驱动次临界系统的中子动力学分析的要求.基于改进的准静态方法,选取临界权重函数模型和全局稳态权重函数模型分别计算一维次临界平板堆启堆过程和断束工况下的中子动力学结果,通过与时空动力学方程直接求解结果对比来深化对权重函数的认识:在外源驱动次临界系统中,权重函数应具有"次临界堆中子价值"物理意义;共轭外源项表征了堆芯内某一位置对外源中子的响应,与外源中子在该位置存在的概率有关.在此基础上提出的局部稳态权重函数模型,用裂变因子乘以权重系数作为共轭外源项.实践表明,采用局部稳态权重函数模型获取的中子动力学结果的准确性得到了提升.

On the Weighting Function of the 1D Slab Source Driven Subcritical System

In the quasi-static framework, the kinetic parameters are obtained by the convolution of weight functions,dynamic operators and shape functions. The weight function in the traditional method cannot satisfy the requirement of the neutron kinetics analysis for ADS,which is a subcritical system driven by the exogenous source.In this article,the critical weighting function of kinetics (cwk) and the global weighting function of kinetics (gwk) are adopted for the calculation of the neutron kinetic results for the one-dimensional subcritical plate reactor by Improved Quasi-static (IQS) method. And then, the physical meaning about the weighting functions can be clarified by comparing the results by IQS with the result obtained directly by the spatio-temporal kinetic equation. In the exogenous driven subcritical system,the weight function should have the physical meaning of subcritical neutron value and the conjugate external term represents the response at one position in the core.The neutron''s response is related to the probability that exogenous neutrons exist in that location. Based on the assumption,the local weighting function of kinetics (lwk) model is proposed. The fission factor is multiplied by the weight coefficient as the conjugate external source term. The results show that the accuracy of the neutron kinetics obtained by using the lwk model has been improved.