An ultrasonic measurement system and its robotic deployment into vessels for the combined assessment of debris condition and water leakage

福岛第一核电站(1F)的退役对日本来说是一项高度优先的任务，全球范围内的退役都有值得吸取的教训。目前的情况是，反应堆被水淹没，燃料碎片的位置和分布尚不清楚。一个特别设计的机器人进入了安全壳，然而，进入受到严格限制。该项目将调查超声波测量系统及其机器人部署的潜力，以评估主安全壳和反应堆压力容器淹没区域内的条件。超声波测量在这一应用中特别有吸引力，因为它们可以克服与水中能见度低相关的问题，此外，传感器体积小，对放射性不敏感。我们建议开发三个超声波测量系统，集成到一个适合机器人部署的紧凑包中。前两个传感器系统将在大尺度(米)和小尺度(厘米)上测量流量。这将使泄漏点的定位和量化成为可能。这些都是已知的存在，因为水目前不断地被泵入反应堆。此外，还将开发超声波传感器阵列，对容器内部进行成像，并对燃料碎片进行定位和量化。还将尝试对碎片内部进行成像，以发现其结构完整性。这些信息最终将被提供给安全清除碎片的尝试。这些测量系统将被建造并集成到机器人平台中，并在基于实验室的复制品上进行测试。该项目将结合日本在超声波流量测量和机器人技术方面的专业知识，以及英国在超声成像方面的专业知识。这项研究将为福岛第一核电站1F反应堆的退役奠定基础，并为英国和世界各地的退役活动提供有价值的新技术和专业知识。

The decommissioning of the Fukushima Dai-ichi Nuclear Power Site (1F) is a high priority for Japan and there are lessons to be learned for decommissioning across the globe. The current situation is that the reactor is flooded with water and the location and distribution of the fuel debris is unknown. A specially designed robot has gained entry to the containment vessel, however, access is severely restricted. This project will investigate the potential of an ultrasonic measurement system and its robotic deployment to assess the conditions within the flooded regions of the primary containment vessel and reactor pressure vessel. Ultrasonic measurements are particularly attractive in this application as they can overcome the problems associated with poor visibility in the water in addition to which the sensors are small and insensitive to radioactivity. We propose the development of three ultrasonic measurement systems integrated into a compact package suitable for robotic deployment. The first two sensor systems will measure flow on a large-scale (meters) and on a smaller-scale (centimetres). This will enable the location and quantification of leakage points. These are known to exist as water is currently being continuously pumped into the reactor. In addition ultrasonic sensor arrays will be developed to image the interior of the vessels and locate and quantify the fuel debris. Attempts will also be made to image inside the debris to discover its structural integrity. This information will ultimately feed into attempts to safely remove the debris. These measurement systems will be built and integrated into a robotic platform and tested on a laboratory-based replica. The project will combine expertise on ultrasonic flow measurement and robotics from Japan with expertise on ultrasonic imaging from the UK. The research will lay the foundation for the decommissioning of the Fukushima Dai-ichi 1F reactor and provide valuable new techniques and expertise for decommissioning activities in the UK and around the world.