22 In conversation | Amanda Smith For internal inspections that present collision hazards, the Elios 1, 2 and 3 UAVs are used, which have integral protective cages. “That’s not to say we can rule other types out, as Elios is relatively expensive, and if we are going to put them into areas with radioactive contamination, potentially we won’t be able to get them back. However, we have proved their value on many tasks to date.” All of the UAVs except the Elios 2 and 3 are ageing. The DJIs are being slowly phased out and the team is looking for replacements for the Falcon 8 fleet. Sellafield’s UAV team has two Skydio quadcopters for use in beyond-visualline-of-sight (BVLOS) operations, for which they are currently going through the process of obtaining Civil Aviation Authority permissions, Smith says. Each UAV has its own suite of sensors. The most used are Lidar, along with a variety of camera systems for video, thermography and photogrammetry. Smith says the team is also considering trialling a UAV-based, non-destructive testing (NDT) capability, and they have received demonstrations from potential suppliers, including Voliro. The company’s multicopters are designed to fly at a wide range of attitudes and feature rotor guards that enable them to apply an ultrasonic non-destructive testing (NDT) contact probe to the surface under testing. When it comes to developing such new capabilities, the team seeks to anticipate future needs. Historically, at Sellafield, Smith says the approach was to wait for someone to ask, but “now we are doing it differently. We know there’s a need out there, and we know what the technologies can do, and will soon be able to do.” This, she adds, enables the UAV team to suggest new ways of doing things to their customer at Sellafield, while also nudging the UAV industry in directions the team would like it to take. Contaminated area ops Any of these vehicles may have to fly into contaminated areas to carry out inspections, which raises issues around their decontamination and retrieval. “We work closely with the plant areas that we’re going to be flying in, so we understand what their contamination levels are, and what the risk is of contamination entering any parts of the systems,” Smith says. “If they can monitor their equipment and prove there’s no contamination anywhere, then we can get our systems back out, and that’s fine.” Decontaminating the UAVs can be difficult as air is drawn through the motors to cool them, and it is not usually possible to take them apart to physically check for contamination. “We’ve got multiple areas across the site where a drone has been flown in and now has to stay. They can be used for future tasks within those buildings or plants, so they are not sacrificed completely,” Smith says. Those vehicles must be maintained while they remain operational, and this mostly involves changing batteries, which generally prove to be clean when checked, so they can be taken back to the UAV team’s maintenance facility. However, with more involved tasks, such as changing propellers or motors, or carrying out a thorough check, it has to be done in situ, wearing personal protective equipment (PPE). “We always make sure, where possible, that we can either get the system to a location where we can maintain it, or if we can’t physically get in ourselves, we work with the plant to determine whether they have operators that we can train up to carry out basic tasks,” Smith says. When selecting new vehicles, any elements of their design that make it easier to work on them in PPE are important, she says, “because for some of these areas we’re talking about, they’re going into [them] in full PVC air-fed suits, and possibly three pairs of gloves. You’ve lost a lot of your dexterity when you’ve got that many pairs of gloves on.” Anything sharp on the vehicle is a potential hazard. The team must consider what to do if a vehicle suffers a failure and becomes stuck in a contaminated area. Any such case will receive its own risk assessment. “Each individual plant will look at the risks to understand what is the worst that can happen,” Smith says. “We will tell them the worst thing that will happen is that they will have a UAV with a lithium-ion battery stuck in the area. They will look at their safety cases and decide whether the risk is acceptable under the ALARP principle.” April/May 2024 | Uncrewed Systems Technology The 6 km2 Sellafield site has many contaminated areas, containing safety-critical structures and pieces of equipment that must be inspected
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