近临界系统中子倍增时间行为的实验测量

为确定近临界系统内中子倍增因子随时间的变化与系统的反应性的关系，为反应堆启动提供参考，实验测量了中心中子在1个快中子临界装置3个次临界状态的中子倍增的时间行为，在反应性ρ=-2.27×10^-3和-4.79×10^-4的两个次临界状态下，阶跃加入反应性，分别等待180和450s后，中子密度（正比于中子倍增因子）才达到稳定值。与单群缓发中子假设计算的变化曲线比较表明，实验测量的中子倍增因子的变化比理论预估的变化快。即使如此，在反应堆启动中，仍需考虑中子倍增的延迟，以便推算正确的反应性。

Neutron Multiply Process Measurement in Subcritical System

The leaked neutron multiplication constant of a fast critical assembly was measured by a long BF₃ counter to analysis the neutron density increase rate with time when reactivity was inserted. The neutron density increased rapidly, and became stable after 180 and 450 s respectively for the reactivity of ρ=-2.27×10^-3 and -4.79×10^-4 when reactivity was inserted. Compared with the calculated neutron density increase rate on the assumption of single group of delayed neutron, the measured rate is a little faster. Even so, the delay of neutron density increase must be considered when startup a reactor.