快中子脉冲堆弱源爆发脉冲实验理论研究

Theoretical Research of Weak Neutron Source Induced Bursts in Fast Neutron Reactor

我们在应用Hansen理论研究快中子脉冲堆弱源爆发脉冲实验时发现,理论与实验结果差距非常大。对此,我们分析了原因,然后从求解系统中子数概率分布函数出发,研究和求解了系统有限长裂变链的期望值,给出了有限长裂变链期望值的求解方法和基本形式,讨论和定量计算了Godiva-Ⅱ和CFBR-Ⅱ脉冲堆有限长裂变链的期望值。然后研究了有限长裂变链导致缓发中子先驱核增值行为,结果表明,在等待爆发脉冲期间缓发中子数可发生数倍的变化。最后,在两种不同的物理假定下,对Hansen模型给予了改进。改进后的模型可以较理想地模拟Godiva-Ⅱ和CFBR-Ⅱ两个脉冲堆的实验结果,表明结果是可信的。

We find that theoretical calculation using Hansen’s model is significantly different from experimental results of weak source induced busts.Based on solution of the probability of n neutrons at time t,the expected length of finite fission chain is evaluated and the multiplication of delayed neutron precursors is studied,which indicate that the number of delayed neutrons may vary several times during the waiting time.With consideration of the multiplication of delayed neutron precursors,an improved theoretical model of probability distributions of burst wait-time is presented,which consist well with experimental results of Godiva-Ⅱand CFBR-Ⅱ.