Fusion Energy Slithers Closer

Online Editor

What role can a robotic snake play in advancing fusion energy? Kelly Lea explains

Achieving sustainable fusion energy is one of the greatest scientific and engineering challenges of our time, with the rewards promising a step-change in the world’s energy supply.

Based on the same processes that power the sun and the stars, fusion has the potential to provide ‘baseload’ power, complementing renewable and other low carbon energy sources as part of the world’s energy portfolio.

The UK Atomic Energy Authority (UKAEA) in Oxfordshire is focussing its expertise on creating an entire sector to overcome the challenges to make fusion commercially viable. Robotics is key to this success, not only for the maintenance of fusion energy power stations, but also for the design.

Located at UKAEA’s Culham Science Centre campus, alongside buildings that house fusion energy machines and materials research scientists, is UKAEA’s world-leading robotics centre, RACE (Remote Applications in Challenging Environments).

Tristan Tremethick, lead mechanical design engineer at UKAEA’s RACE, says: “Current fusion experiments were primarily designed to investigate plasma physics. However, prototype powerplants must demonstrate the necessary technologies for regular, rapid, and reliable maintenance of the plant.

“The design of fusion energy prototype powerplants such as the UK’s STEP (Spherical Tokamak for Energy Production) programme led by UKAEA in addition to EUROfusion’s DEMO programme, must take account, not just of physics requirements, but also of engineering and technological limitations.”

Snaking Ahead

The latest development to come out of RACE is a new laser-welding ‘robotic snake’ that has demonstrated its capability to operate inside an intricate network of pipework located within a fusion energy powerplant.

The novel trials are another step forward on the roadmap to delivering safe, sustainable, low carbon fusion energy to the grid, and the technology is now patented.

The £2.7 million, seven-year project was delivered as part of EUROfusion’s flagship DEMO programme, expected to be ITER’s successor – a fusion energy machine currently being built in France.

The DEMO snake will be deployed and operated remotely inside a hazardous environment without being touched by humans. It can also work effectively in pipes packed together, with little space for access.

Tremethick says: “In fusion machines, pipework has to be connected and disconnected remotely because of the hazardous environment. Pipework in DEMO is extra challenging because of the limited workspace. We’ve been looking at different ways of tackling this, and I’m delighted our snake has passed its first set of trials.

“The bespoke laser welding tool takes a novel approach and operates inside of the pipework to make the best use of the cramped space available. At RACE, we pride ourselves on providing complete solutions to enable operations and protect people in challenging environments, and this is another exciting result on our path to delivering fusion energy.”

In addition to solving the challenge of laser welding in a small space, Tremethick’s team also had to solve the conundrum of deploying and positioning the tool. This involved creating a launch system to feed the snake into the pipework and a sensor-system to identify each precise working location.

Tremethick adds: “Ultrasonic sensors enable the snake to find the correct position, where it then clamps to the pipe and performs the weld from the inside. After the weld, the tool retracts and is removed from the pipe where it can be redeployed.”

The pipes are made from Eurofer97 to withstand extreme heat, which is similar to the P91 grade stainless steel used in powerplants but modified for the extra demands of fusion.

The number of pipes to be welded will depend on the final design of the fusion powerplant. There are expected to be around 16 segments making up the machine, each containing six blankets that extract the fusion energy. Each blanket requires approximately five pipes. This gives a total of 480 welds that must be achieved remotely and to the highest standards.

RACE has also developed a laser cutting tool operating on the same principles as the snake, and both can potentially be used for other industry applications. 

Tremethick comments: “Robots are a key part of our mission to deliver low carbon fusion energy, and we need to become skilled in controlling machines such as this one remotely. We won’t be able to send people inside fusion energy powerplants, and robots will keep them running – it’s the future.”

Since opening at Culham in 2016, UKAEA’s 300 roboticists at RACE have conducted R&D into the use of robotics in extreme industrial environments where it is difficult to send people to carry out work.

Challenging conditions are found in environments such as fusion energy machines, nuclear decommissioning, petrochemical facilities, space exploration, construction and mining, to name a few.

These environments can include high radiation, extreme temperatures, limited access, operation in vacuum and magnetic fields.

The Role Of Robots

RACE is a key centre for implementing the Government’s Robotics & Autonomous Systems strategy, which aims to equip the UK to compete in this emerging global industry. It also supports companies developing their own autonomous systems through close collaboration with industry partners and academic institutions.

Robots are the next generation of smart tools that people will use in a whole variety of sectors. According to Tremethick and the RACE team, robots will increase safety, increase productivity and increase opportunities for industry and people.

Kelly Lea is with UK Atomic Energy Authority