The Design of UnderGRND: Underwater Gliders - Remote Sensing for Nuclear Decommissioning

Abstract

The requirement for long-term, autonomous, remote sensing of cluttered underwater environments poses a number of research challenges when designing inspection vehicles. Tethered vehicles have a ready source of energy for propulsion and a link for communication, however, the tether limits their range and their ability to operate in cluttered environments. If untethered vehicles are to be used in remote applications, then low-energy locomotion technologies must be considered. Wireless communications also need to be considered along side autonomous operation. The theory, design and implementation of an Underwater Glider is presented in this paper. Underwater Gliders are a novel mechanism for locomotion that use a variable volume ballast to change buoyancy, propelling the vehicle in a given direction. As energy is primarily required to change direction, it is particularly attractive for moving distances much greater than the vehicle size itself. The primary motivation behind investigating Underwater Gliders in this paper is a use case in Nuclear Decommissioning. Spent fuel from Advance Gas-cooled Reactors is stored in ponds before can be disposed of, in around 60 years time. During this time, the fuel needs to be monitored for leaks and increased nuclear activity. This paper discusses the design, prototyping and experimental evaluation of the use of small scale (50 cm length) Underwater Gliders for untethered remote sensing.