ABSTRACT To estimate the subcriticality in dollar units for an arbitrary state-change, the time-domain decomposition-based integral method (TDDI) is proposed using the point kinetics theory based on the fundamental mode approximation. In a general transient subcritical system, reactivity, neutron source intensity, and point kinetics parameters can vary simultaneously. Furthermore, the state-change may not necessarily be a stepwise change. For such a transient, the TDDI method can estimate the subcriticality after the transient using only the time variation of the neutron count rate. Therefore, the proposed method is useful to approximately estimate the subcriticality in a system where a detailed core configuration is unknown. To investigate the applicability of the TDDI method, transient experiments with simultaneous reactivity and source changes or to two successive safety rods dropping were performed at the Kindai University Training and Research Reactor (UTR-KINKI). By comparing with reference values using excess reactivity and control rod worth, it was validated that the subcriticality values obtained by the TDDI method better agree with the reference values than the previous integral method.

中文翻译：

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使用基于时域分解的积分方法同时反应性和源变化的亚临界测量

摘要 为了估计任意状态变化的美元单位次临界性，提出了基于时域分解的积分方法 (TDDI)，使用基于基本模式近似的点动力学理论。在一般的瞬态亚临界系统中，反应性、中子源强度和点动力学参数可以同时变化。此外，状态变化不一定是逐步变化。对于这种瞬态，TDDI 方法可以仅使用中子计数率的时间变化来估计瞬态之后的亚临界性。因此，所提出的方法对于在详细核心配置未知的系统中近似估计次临界是有用的。为了研究 TDDI 方法的适用性，在近代大学训练和研究反应堆 (UTR-KINKI) 进行了同时反应性和源变化或两个连续安全棒下落的瞬态实验。通过与使用过量反应性和控制棒价值的参考值进行比较，验证了 TDDI 方法获得的亚临界值与参考值比以前的积分方法更符合参考值。