A new facility designed to support the retrieval of waste from two of Sellafield’s most hazardous legacy facilities has begun operation in the UK. The Silo Maintenance Facility will maintain the equipment used to retrieve radioactive waste from two of the site’s legacy nuclear waste storage facilities - the Magnox Swarf Storage Silo (MSSS) and the Pile Fuel Cladding Silo (PFCS). It will also maintain the flasks that will transport the waste from silos to modern storage facilities that are being constructed on the site.
Over the past eight years Sellafield supply chain partners Balfour Beatty and Cavendish have constructed the new facility, with building work and equipment installation completed in April 2019. The final step was completed recently when the building received its first transport flask from MSSS, signalling the start of active operations. Roddy Miller, Sellafield Ltd’s operations director, said the Silo Maintenance Facility is “geared up to do a vital job for decades to come”.
The start of active operations in the Silo Maintenance Facility is the latest in a series of steps in Sellafield’s work to empty MSSS, moving the waste to modern buildings for safe long-term storage. The first waste was retrieved from the silo in 2022, and earlier in March, the second of three retrieval machines was installed into the silo.
MSSS has stored nuclear waste for the last 60 years and was originally constructed as six silos in the 1960’s and then extended three times. The silo emptying machines are far bigger than any of the entry points into the silo, and have to be lifted in as 22 different modules and then assembled inside the building.
The machines work by lowering a grab into the waste, lifting it back up and placing the waste into a metal skip which is gradually filled and then sent to a separate waste store in more modern, safe containment. With no control over what waste the grab picks up, it’s a ‘lucky dip’ arrangement with every grab.
Each machine weighs 360 tonnes and comprises of around 13,500 working parts. The design, manufacture and assembly of the first machine began more than 20 years ago. It will take another three years of preparation an
d commissioning work inside the silo before the machine can start retrieving waste. Neil Rogerson, Sellafield Ltd senior project manager, said: This is a big moment for ‘machine number 2’ – we’ve fully rebuilt it inside the silo and can now start the job ahead of making it work.”
All three machines were originally designed and manufactured in Wolverhampton by Ansaldo NES, and are now the responsibility of Sellafield Ltd and the Decommissioning Delivery Partnership Framework Partner - i3 Decommissioning Partners.
Gary Kershaw is one of the i3 engineering team who assembled this second machine, he said: “It’s a big task involving lots of different skills: fitters, riggers, electricians and all the people behind the project too. At any given time during assembly there’ll be roughly a dozen people in our team working on site and half a dozen people at the off-site locations. Everyone knows just how important getting this right is.”
According to Sellafield, MSSS and PFCS are the most hazardous nuclear facilities at the site. They were not designed with decommissioning in mind. Equipment has now been built that can be used to reach inside these legacy silos to grab the waste and put it into high integrity storage containers. This retrieval work will take 25-30 years to complete. An onsite facility was needed where it would be possible to maintain the retrievals equipment and the transport flasks that will take full containers of waste from the silos to modern storage facilities.
The Silo Maintenance Facility was built on the footprint where two of the iconic Calder Hall cooling towers used to stand. It enables road receipt and despatch of tools and equipment as well as clean storage and the ability to receive and export transport flasks. Site clearance began in 2011 and construction was completed in 2018. Installation of plant equipment was completed 2019 and the facility was formally commissioned from 2020-2022. More than 21,000 tonnes of concrete were used in the construction. More than 4,000 metres of pipework was laid and more than 8,000 metres of cables were installed. The facility will use 11 internal cranes to carry out maintenance work.
The facility will:
- manage and maintain an initial fleet of 22 internal transport packages;
- provide an import route for waste containers into PFCS environmental boxes;
- store spare components for the Silo Emptying Plant machines for MSSS;
- provide storage for Silo Emptying Plant machine maintenance flasks; and
- provide a disposal route into intermediate level waste streams for failed machinery components.
Images: Top left - Interior of the new Silo Maintenance Facility on the Sellafield site; Right - One of the silo emptying machines installed in the Magnox Swarf Storage Silo at the Sellafield site (images courtesy of Gov.UK)
