Opticlean: Successful demo of laser cleaning tech in Japan

Last month (Oct 2023), researchers working on ‘Opticlean’ from the University of Bristol travelled to Tokyo, Japan, to demonstrate novel technology which could contribute to the ongoing decommissioning of the Fukushima nuclear reactor.

Supported by Bristol Hot Robotics, the small team comprised of Prof Tom Scott, Dr Dave Megson-Smith, and specialist technician Tom Bennett were able to showcase the results of successful collaboration with University of Tokyo and ATOX, a Japanese decommissioning company.

Three men in hard hats are stood deep in a large metallic cylinder - a full scale mock-up of a Fukushima nuclear reactor. They stand around a rotor arm stuck to the wall. — The University of Bristol Opticlean team showcasing the laser mounted robotic arm

Opticlean, as part of the JUNO phase 8 project (a UKRI funded network of academics in the UK and Japan working on nuclear decommissioning and waste management), focuses on using laser cleaning to remove residual nuclear material in the Fukushima reactors.

The Bristol team mounted a low-power pulsed laser on the end of a robotic arm and created a supporting frame which can be craned in through the top of the damaged reactors. Industrial suction cups adhere to the reactor surface and hold the robotic arm in a fixed position, allowing the laser to clean complex surfaces without damaging the underlying steel structure, minimising waste.

A black and white image. In the centre of the photo a bright light casts a silouette of one man - Tom Bennett, and lights up the face of another man - Tom Scott. The rest of the photo is cast in shadow. — Tom Bennett and Tom Scott demonstrating the laser

ATOX provided a full-scale mock-up of the Fukushima reactor for the team to test the robotic system in, enabling them to modify and experiment with different parameters in a safe environment. To avoid contamination of the surrounding atmosphere, water mist was created using an ultrasonic device and fed past the laser beam to mix with the displaced particles, which are then sucked away to a separate containment vessel. The University of Tokyo group worked on fluid dynamic modelling to optimise the mist generation system and its flow path around the laser beam.

The visit enabled a successful demonstration of the use the robotic arm to clean rusty surfaces without damage to the underlying steel and demonstrated the robot's ability to securely attach to the smooth walls of the reactor chamber.

Tom Scott, RAEng Professor in Nuclear Materials at the University of Bristol, is really pleased with the outcome of the visit:

“This trip was a major success and being able to demonstrate the technology directly to parties involved with the clean up of Fukushima has provided a fitting end to the project.

A line of men in hard hats smile at the camera. The group is made up of the three Bristol team members, and 5 ATOX team members. — A successful collaboration!

We hope that this technology will make a substantial difference to nuclear decommissioning in the UK and worldwide. This work can be applied beyond Fukushima, contributing to the decommissioning of other industrial plants, so has implications much wider than nuclear.”