Mitsubishi Unveils Underwater Robot for Nuclear Reactor Inspections

Mitsubishi Heavy Industries has introduced a state-of-the-art underwater navigation robot designed for inspecting nuclear reactor vessels in Japan. The robot, named the A-UT Machine, is engineered to conduct non-destructive examinations in high-radiation environments, enhancing safety and efficiency in nuclear plant operations.

The A-UT Machine measures 1.8 metres in length, 1 metre in width, and 0.9 metres in height, weighing 400 kilograms when on land, though it becomes buoyant when submerged. This innovative device operates using thrusters and wheels, enabling it to glide along reactor vessel walls while performing critical inspections.

Real-time tracking is a key feature of the A-UT Machine. It utilizes a target mounted on the unit, employing triangulation for precise orientation. The robot is equipped with a seven-axis manipulator arm, capable of supporting a load of up to 10 kilograms with a positioning accuracy of ±0.1 millimetres. This arm also features a tool changer, allowing for the interchange of inspection tools as needed.

The A-UT Machine can dive to depths of up to 20 metres, making it suitable for various underwater inspection tasks. Its remote operation is facilitated through a desktop computer and joystick, enabling operators to control the unit from a safe distance.

According to the developers, operating two A-UT Machines simultaneously significantly reduces inspection time, streamlining maintenance processes at nuclear facilities. The technology has been in use at pressurised water reactor (PWR) plants across Japan since 1995, with 46 deployments recorded to date.

The Japan Society of Maintenology has recognized the A-UT Machine as the #1 Maintenance Heritage, highlighting its importance as a historic and cultural asset in maintenance technology. This certification underscores the robot’s contribution to enhancing safety and reliability in nuclear plant operations.

The introduction of the A-UT Machine marks a significant advancement in nuclear inspection technology. As the industry continues to evolve, innovations like this robot will play a crucial role in ensuring the safety and efficiency of nuclear energy production in Japan and beyond.