Drone test flights prove possibilities for use in fusion

Due to the Joint European Torus's (JET's) complex, crowded, and highly sensitive environments, the use of drones had been highly restricted, despite the value of remote inspection. However, in late 2025, history was made with the first JET inspection drone flights - first in October as a derisking exercise in the JET in-vessel training facility, then in the JET assembly hall, and finally around the exterior of the JET torus itself, between 25 and 26 November.

The flights were jointly conducted to gather data to serve the needs of four parties. The Robotics and Artificial Intelligence Collaboration (RAICo) led a project to conduct inspection flights, with the aim of gathering safety inspection data and establishing the processes to support future inspections as it proceeds along its decommissioning journey.

At the same time, a separate collaboration between UKAEA's RACE (Remote Applications in Challenging Environments) robotics centre, Eni and EniProgetti, supported by RINA, explored how they could use drones, alongside other inspection systems, to enable rapid checks of fusion devices and help verify system readiness. This approach aims to significantly shorten the time required for these assessments, a critical step for meeting the stringent reliability standards demanded by commercial fusion power plants. They were also keen to further understand the use of aerial drones for rapid inspection of fusion facilities, to complement ground-based inspection techniques.

To ensure safety, the teams conducted a detailed risk assessment, secured access permissions, completed local inductions and implemented safety measures, including post-flight contamination swabbing. On the day, the flights used a Flyability Elios 3 drone which undertook over 30 flights of 6-7 minutes (the limit of a single battery) in JET's torus hall.

The drone is equipped with built-in camera and LiDAR, and radiation sensors were added as a payload, which let it gather detailed data and high-resolution imagery. It is surrounded by a lightweight soft cage, allowing it to operate near sensitive structures without risk to itself or its surroundings.

The RAICo team also used the opportunity to carry out a real inspection of high-up junction boxes. That data proved useful, highlighting minor maintenance issues.

_{(Image: RAICo)}

"The flights successfully demonstrated that drone-based imaging and inspection can be performed safely to support [decommissioning and repurposing] activities and provided valuable learnings for future flights," UKAEA said. "If adopted, drones could save time and money. For example, they would avoid the need to carefully erect scaffolding to inspect equipment at height, which is time-consuming in a controlled area. The initial inspection data captured from the flight, which has already improved one aspect of maintenance, hints at the wider potential.

"These flights and the lessons learned pave the way for aerial drone use at JET, and in fusion engineering and decommissioning more widely. This aims to lead to enhanced situational awareness, reduced inspection time and downtime, and better data quality that can be easily integrated into a digital environment and artificial intelligence models. All of that will be achieved whilst reducing the need for people to enter harmful environments."

JET was a tokamak fusion system with a doughnut-shaped vacuum chamber where, under the influence of extreme heat and pressure, gaseous hydrogen fuel becomes a plasma. The charged particles of the plasma can be shaped and controlled by massive magnetic coils placed around the vessel to confine the hot plasma away from the vessel walls. It was the only tokamak fusion machine in operation capable of handling tritium fuel, and was a key device in preparations for the multinational ITER fusion research project which is currently under construction in southern France.

JET was a European project built and used collaboratively by European researchers. It is now owned, and in its last years operated by, the UKAEA, and used by scientists from 28 European countries to conduct research into the potential for carbon-free fusion energy in the future through work coordinated by the EUROfusion consortium. The tokamak's first deuterium-tritium experiments took place in 1997.

JET's final experiments using deuterium and tritium fuel were conducted over seven weeks from August to October 2023, ahead of its retirement following its final pulse in December. During those experiments, JET produced the largest amount of energy achieved in a fusion experiment, breaking its own record set in 2021. Following its retirement JET has moved on to repurposing and decommissioning, a process expected to last until about 2040, and which is seen as providing further opportunities to discover and develop new technologies and skills for future fusion.

JET is now in the early stages of being decommissioned and repurposed by the UKAEA, under the JET Decommissioning and Repurposing (JDR) programme.