基于波形逼近的快中子脉冲堆耦合计算

Waveform Approximation-based Coupled Computation for Fast Burst Reactor

快中子脉冲堆在爆发脉冲过程中的中子输运与热弹性力学相互耦合,该耦合作用过程决定了脉冲特性。基于绝热近似下燃料元件温升始终正比于系统总裂变数的事实,提出了通过调整参数使温升随时间变化的曲线逼近裂变率曲线的耦合计算方法。在迭代逼近过程中,采用了有限元商业软件ANSYS处理力学建模和热弹性力学求解,利用点堆方程描述中子学行为,两者利用基于微扰理论的反应性反馈方程进行耦合。通过调整参数使力学模型的温升加载函数波形逼近通过输运计算得到的裂变率波形,直至两者一致。以Lady Godiva脉冲堆为例的裂变产额计算结果与实验结果一致,该计算方法有望用于快中子脉冲堆的研究和设计。

The neutron transport and thermo-mechanics of fast burst reactor are coupled with each other during the pulse excursion,and the coupled process has a decisive effect on the pulse properties.With the adiabatic assumption,a novel waveform approximation-based coupled computation method was introduced based on the fact that the temperature increase of fuel is always proportional to the total fission number.The mechanics modeling and the elastic wave equations＇ computations were treated by commercially available finite element software ANSYS,and the neutronic model was determined by the point reactor kinetics equations.The mechanics and neutronic models were coupled with the reactivity feedback equation based on perturbation theory,and the parameters were adjusted until the computed rate waveform of fissions approximated that of the input temperature increase.The computed fission yield of Lady Godiva is in accordance with experimental result,and the proposed method has the potential to be used in futurestudy and design of fast burst reactor.