Measurement of Coupling Coefficient by Variance-to-Mean Ratio Method, and Investigation of Its Space-Dependence

在临界安全管理中，一个重要的问题是评估核燃料单元间中子干扰的影响。作为对这种效应的度量，我建议使用耦合系数来表示耦合堆芯中堆芯之间的耦合强度。本研究采用方差-均值比值法，并以近机大学原子能研究所的argonout型偶芯堆为实验对象，对该方法的有效性进行了研究。通过本研究得到以下结果：1。测量系统的死区时间在数据处理中起着重要的作用。然后，推导了考虑死区时间影响的新公式，并验证了其有效性。采用数据记录仪的数据采集技术。然后发现，为了得到好的统计数据，需要4万多个采样点。但是，尽管采用了这种技术，在较大栅极宽度的实际采集时间内难以获得足够的采样点。测量到的耦合系数为1.99+0.53美元，与实验误差范围内的计算值2.33美元一致，用二维双能群扩散理论对其进行了评价。

In the management of criticality safety, an important problem is to evaluate the effect of neutron interference between nuclear fuel units. As a measure of this effect, I have proposed to use the coupling coefficient representing the strength of coupling between cores in a coupled-core reactor.In this study, the variance-to-mean ratio method was employed, and its availability was investigated with the use of the Argonout-type coupled-core reactor at Kinki University Atomic Energy Research Institute.The following results were obtained through this study.1. The dead-time of a measuring system plays an important role in data processing. Then, the new formula taking account of the effect of dead-time was derived, and its validity was confirmed.2. The data acquisition technique with a data-recoder was employed. Then, it was found that the sampling points more than 40,000 were required in order to get good statistics. But, in spite of this technique, it was difficult to obtain the sufficient sampling points within practical acquisition time at large gate width.3. The coupling coefficient measured was 1.99+0.53 dollars, and it agreed with the calculational value of 2.33 dollars within the experimental error, which was evaluated by two-dimensional, two-energy group diffusion theory.