Wall Inspection Robot

The Challenge

Sellafield Ltd has a section of the primary containment wall at the Magnox Swarf Storage Silo (MSSS) obscured behind a secondary section of concrete shield wall, this obscured section of the primary containment has had limited inspection for several decades, posing a concern over potential leaks and cracks. Surveying and identifying the leaks and cracks is required for leak mitigation purposes. Intermittent monitoring will be required to determine if the cracks are evolving, and to monitor for further deterioration of the primary containment wall as the load is increased to the structure over the next two years. The location, dimension and activity of the crack or leak is essential for this process.

The Solution

A deployment system was designed for the100mm gap between the primary containment wall and the freestanding shield wall. It can deploy any small tool or sensor into the cavity, with the initial focus being to deploy a radiological instrument. The solution selected consists of two parts; a locomotion carriage running in a linear rail and a sensor payload that is lowered down behind the wall on steel cables. The linear rail is made of modular sections of steel extrusion, each section can be individually installed

under a bracket, removing the need of heavy lifting equipment for installation. During operation the carriage is driven along the underside of the linear rail via an onboard stepper motor, enabling precise control and monitoring of the carriage position. This carriage contains a winch mechanism to raise and lower the sensor payload on two steel cables, enabling it to be positioned at any location behind the shield wall. The winch mechanism is strong enough to lift a payload of 40Kg. The sensor payload is a low-cost and easily replaceable enclosure that can be equipped with a wide range of COTS instruments. A modular electronics interface allows data from any sensor or instrument to be logged and transmitted to an operator in real-time. In addition to the main interchangeable sensor, the payload section is equipped with an onboard camera and lighting to aid operation and provide images of the wall cavity. Amentum led the hardware design and implementation of the robot and collaborated with Cerberus Nuclear on instrumentation and data analysis.

Benefits / Highlights

• Allows inspection of tight cavities.

• Modular system customisable for various COTS sensors.

• Cost-effective and easy assembly process.

Future development

Develop, test and demonstrate a UKCA marked production unit on a full-scale rig.