ABSTRACT

A Compton camera system for use on an unmanned helicopter was previously developed to characterize the distribution of radioactive materials in highly contaminated areas. For this study, a Compton camera system was equipped with a small camera, laser distance meter, an attitude angle sensor, temperature sensors, and real-time monitoring software for better measurement of flight parameters and more precise detection of hot spot locations. To confirm whether the detection results were improved by the modifications, ground-level ambient dose equivalent rate distributions were derived from hovering and programmed flights over a field in Okuma, Fukushima Prefecture (Japan) and compared against readings from survey meters taken at the ground level. For one hovering flight, the correlation between the datasets was improved by selecting a period of stable flight position and attitude and restricting the deviation of the attitude angles. Between 6.0% and 7.6% improvement in the position resolution was achieved using the data from stable flight periods, even when only 1-minute data windows were used. The precision of hot spot detections and ambient dose equivalent rate distributions obtained from the Compton camera were thus improved by the aforementioned modifications to the system.

摘要

以前开发了一种用于无人驾驶直升机的康普顿相机系统来表征放射性物质在高度污染区域的分布。在这项研究中，康普顿相机系统配备了小型相机、激光测距仪、姿态角传感器、温度传感器和实时监控软件，以更好地测量飞行参数和更精确地检测热点位置。为了确认修改后的检测结果是否有所改善，地面环境剂量当量率分布来自于在福岛县（日本）大隈市上空的盘旋和程序飞行，并与地面测量仪的读数进行比较. 对于一次悬停飞行，通过选择一段稳定的飞行位置和姿态，并限制姿态角的偏差，提高了数据集之间的相关性。即使只使用了 1 分钟的数据窗口，使用稳定飞行期的数据也实现了 6.0% 到 7.6% 的位置分辨率改进。因此，通过对系统进行上述修改，提高了从康普顿相机获得的热点检测和环境剂量当量率分布的精度。