能量大于1.692MeV的γ射线能够与铍或氘等“靶核”发生(γ,n)反应。所以用铍作反射层的反应堆运行时,活性区内会存在少量的光致次生中子,反应方程式如下:9Be+γ→2α+n-1.67MeV这些中子的存在增加了缓发中子数目,从而影响了不同状态时反应堆的反应性。某铍反射层小型反应堆上大量的实验测量数据表明,在引入较大的阶跃反应性后,反应性随时间的衰减曲线尾部 Gamma rays with energies greater than 1.692 MeV can react with (γ, n) “target nuclei” such as beryllium or deuterium. Therefore, when beryllium is used as a reflector, a small amount of photo-induced secondary neutrons will exist in the active region. The reaction equation is as follows: 9Be + γ → 2α + n-1.67MeV The presence of these neutrons increases the amount of delayed neutrons The number of reactors that affect the state of the reactor at different states. A number of beryllium reflector small reactor experimental data show that after the introduction of a larger step reactivity, the reactivity curve with the tail of the tail