金属型脉冲堆惯性效应计算

Calculation of inertia effect on metal burst reactors

金属型脉冲堆的反应性负反馈主要来自燃料的热膨胀。当脉冲堆爆发短周期脉冲时,由于燃料的热膨胀不能及时响应温度的变化,致使负反馈滞后,产生惯性效应。采用ANSYS程序计算了在突然热加载条件下的振荡特性,同时采用随机中子输运程序计算了平均关闭系数,然后把带有振荡特性的热反馈带入点堆动力学方程,采用数值方法求解得到了考虑惯性效应的裂变脉冲波形。计算结果与Godiva实验测量结果一致。采用的数值方法中,脉冲周期与振荡效应存在定量关系。由计算结果可知,脉冲周期短,惯性效应明显;脉冲周期越长,惯性效应的影响越小,金属型脉冲堆爆发脉冲时应尽量避免短周期脉冲。

The reactivity feedback effect of metal burst reactors is driven by the thermal expansion of fuel. The inertia effect on metal burst reactors is caused by delay of reactivity feedback when the material expansion cannot respond to rapid heating chan- ges in time from power excursions. We simulated vibrations by ANSYS under sudden thermal loading, and we calculated quench coefficient on metal burst reactors by stochastic neutron transport program at the same time. After introducing the reactivity feed- back behaviors with vibration into the equations of point reactor kinetics, we obtained waveforms of fission pulses in consideration of inertia effect by numerical calculations, and the waveforms are in agreement with experiment results of Godiva. There is a quantitative relationship between the reactor periods and the inertia effect through numerical calculations, and the inertia effect is obvious when reactor periods are narrow.