A spherical robot equipped with a camera may navigate underground pipes of a nuclear reactor by propelling itself with an internal network of valves and pumps. Image: Harry Asada/d’Arbeloff Laboratory
Now Asada and his colleagues at the d’Arbeloff Laboratory are working on a direct monitoring alternative: small, egg-sized robots designed to dive into nuclear reactors and swim through underground pipes, checking for signs of corrosion. The underwater patrollers, equipped with cameras, are able to withstand a reactor’s extreme, radioactive environment, transmitting images in real-time from within.
He and his graduate student, Anirban Mazumdar, decided to make the robot a smooth sphere, devising a propulsion system that can harness the considerable force of water rushing through a reactor. The group devised a special valve for switching the direction of a flow with a tiny change in pressure and embedded a network of the Y-shaped valves within the hull, or “skin,” of the small, spherical robot, using 3-D printing to construct the network of valves, layer by layer. “At the end of the day, we get pipelines going in all … directions,” Asada says. “They’re really tiny. Depending on the direction they want their robot to swim, the researchers can close off various channels to shoot water through a specific valve. The high-pressure water pushes open a window at the end of the valve, rushing out of the robot and creating a jet stream that propels the robot in the opposite direction.