21 A career in academia followed, much spent in the field of control systems and condition monitoring at the University of Manchester. In 2002, Lennox was involved in creating a successful spinout company, Perceptive Engineering, providing process control solutions. In 2011, he was offered the research chair position in nuclear decommissioning and robotics by the Engineering and Physical Sciences Research Council (EPSRC). “Part of my PhD focused on nuclear and there are lots of potential opportunities for control systems in robotics, so I accepted,” he says. Nuclear debut The first challenge his team tackled at Sellafield was the inspection of a highly contaminated pool in the basement of one of the buildings. There was too much radiation for personnel to enter the water and the floor immediately above the pool was out of bounds for similar reasons. The only access was through a room two floors above where there were 6 indiameter pipes leading down to the pool. Lennox’s team developed a robot that could pass through the pipe to inspect the pool, which was used later to inspect the Magnox swarf storage silos elsewhere on the Sellafield site. “Through this application we instantly understood the difficulties of performing very routine inspections when a human can’t enter the facility and the access ways are very limited. There are very few situations when you can simply open a door and walk in,” Lennox says. “We’ve had to design ground-based, aerial and aquatic robots that can fit through 6 in holes. In the case of aerial drones, we designed them so they had rotors that folded for deployment and retrieval. Our ground-based vehicles had to be reconfigurable. “Maintenance and retrieval are also difficult, and often can’t be done, so if a robot gets stuck then it could potentially block a passageway for years. This is a problem that they have had in the clean-up of Fukushima Daiichi.” Also, the likelihood of radioactive contamination makes it unlikely that once deployed, a robot could be brought back into the lab for maintenance or repair, he notes, as some of the material is mobile and likely to stick to its internal mechanisms. In high-dose environments, the gamma rays can damage the electronic systems enough to render the robot useless, although exactly when it will fail is unpredictable. “This is typically a stochastic process, so a robot could die very quickly or last longer,” he adds. Radiation hardening Hardening a robotic vehicle against radiation can be relatively straightforward, but involves trade-offs. The simplest solution is to place all the electronic components into a metal box called a vault, he says – an approach that was used on the Juno spacecraft that NASA sent to orbit Jupiter. “Radiation in deep space is quite different from what you get on a nuclear facility. In space, larger particles are a bigger problem than gamma and can do more damage, but they are easier to stop. The main problem for nuclear robots is that gamma radiation means the casings to shield the electronics need to be thick, so they can weigh enough to make the robot impractical. We determined that for a very simple mobile robot we would need 20 kg of tungsten to protect it. This was mainly to protect the small processing board,” says Lennox. As some electronic components that are tolerant of radiation are available, his team is developing a robot to exploit this attribute. This machine will use carefully selected encoders to provide the control computer with position feedback and feature a field-programmable gate array (FPGA) developed in Japan, which can operate at very high dose rates. The robot will be low-cost, but will not have the level of functionality typically found in other modern robots. “It will probably just be able to drive a camera into a radiation facility and move around. We hope to be able to equip it with radiation-tolerant Lidar to automatically avoid obstacles, Lennox says.” However, the idea that radiation will kill robots is, for the most part, a significant misconception. “This is true in some cases, but there are many examples Professor Barry Lennox | In conversation Uncrewed Systems Technology | April/May 2025 MIRRAX is an articulating, reconfigurable ground robot, developed to negotiate inaccessible spaces through 150 mm (6 in) apertures, and it is large enough to climb stairs. MIRRAX robots can be equipped with sensors such as mapping Lidars and radiation detectors (Image courtesy of the University of Manchester)
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