This robot swims inside nuclear reactors to keep them safe

Looking a little like a small metal giraffe, the A-UT — an autonomous underwater inspection device — is a remarkable machine.

Fitted with a seven-axis robotic arm that has a sensor pad at the end, its job is to check for faults in the weld lines inside a reactor vessel at the core of a nuclear power plant.

Regularly inspecting the vessel to ensure the soundness of the structure is an important job that a human cannot do: a working reactor vessel is highly radioactive and operates under high temperatures and high pressure.

The A-UT was designed specifically to do this. Watch it in action in the video below.

Fast inspections of in-service reactors

Controlled remotely using a computer and joystick, the A-UT navigates around this hazardous environment, swimming in the water inside the vessel, sticking on the walls with vacuum-pad feet, and using a probe to carry out ultrasonic testing.

It scans the walls of the reactor vessel at a speed of 200 millimeters per second, and when two units work simultaneously, the time required for an inspection can be greatly reduced.

The A-UT has carried out this work at pressurized water reactor power plants across Japan, and has been used about 50 times.

Nuclear power and net zero

The robot was developed entirely in-house at Mitsubishi Heavy Industries (MHI) Group, which provides a full range of services in nuclear power generation, from plant development through to manufacture, operation and maintenance.

With nuclear energy receiving increasing attention as a route to ensuring stable, sustainable power in the global effort to meet net zero goals, such expertise will continue to make an important contribution.