Initially constructed in the 1950s, the Pile Fuel Cladding Silo concrete ‘locked vault’ structure was purposely designed to safely store used cladding peeled away from the reactor fuel rods, alongside other radioactive materials from military projects and power plants, as well as other hazardous debris. The 60ft tall Pile Fuel Cladding Silo structure containing over 3,200 cubic metres of intermediate-level waste across six internal compartments stopped receiving waste in the early 1970s.
Enigma’s role was to support various temporary works requirements as the project team engineered solutions to access the top of the silo’s storage compartments, while maintaining an airtight seal to mitigate the threat of a spontaneous fire within. For the first-time in 65-years, the project team planned to access the storage compartments and retrieve the waste by utilising remote-operated robotics. Once the waste was safely retrieved, it was to be securely packaged in specially designed stainless-steel box containers and transported to the Box Encapsulation Plant Product Store for final disposal. In August 2023, the project team successfully retrieved the first waste from the Pile Fuel Cladding Silo using a crane to reach into the silo, lower a robotic arm into the compartment and lift out and repackage the waste. The boxes of waste are then transferred to the Box Encapsulation Plant Product Store – Direct Import Facility (BEPPS-DIF), which is a new above-ground storage facility that has been specially constructed on the Sellafield site. Enigma also played a pivotal role in the delivery of the BEPPS-DIF project (see separate case study online).
The first retrievals represent a significant milestone in the decommissioning story at Sellafield and a step closer to reducing the UK’s nuclear hazard.