Nuclear regulator hails “landmark moment” in the clean-up of Sellafield

13 June 2022

The UK’s Office for Nuclear Regulation (ONR) has announced what it has called a “landmark moment” in the long-term clean-up of the Sellafield site after Sellafield Ltd safely removed the first batch of waste from one of the most hazardous buildings on the site, the Magnox Swarf Storage Silo (MSSS).

Safely removing the historic waste from this ageing facility and placing it into modern storage facilities is both a national and an ONR priority. Standing in the oldest part of the Sellafield site, the MSSS has stored nuclear waste in its water-filled chambers since it was originally constructed in the 1960s. It is one of the oldest facilities at Sellafield and does not meet modern safety standards. Once a vital part of the nation’s nuclear energy generation, the building stored the casings removed from used fuel rods from Magnox reactors so that the fuel inside could be reprocessed.

Now, due to the age of the building, the contents held inside, and the fact that it was never built with decommissioning in mind, it is one of the most hazardous nuclear facilities on the Sellafield site and in the Nuclear Decommissioning Authority’s (NDA) estate. The structure, which is comprised of 22 compartments, is estimated to hold approximately 10,000 tonnes of radioactive waste which is stored under water.

ONR inspectors spent months reviewing the safety case provided by Sellafield Ltd and only after a rigorous assessment was permission given for Sellafield Ltd to begin removing waste from compartment 10 of the facility.

ONR’s Director of Regulation for Sellafield, Decommissioning, Fuel and Waste Division, Paul Dicks, said: “The waste contained in the silo has been there for many decades and removing it is not without risk, so ONR inspectors will be closely monitoring work that Sellafield Ltd will be conducting and we will have no hesitation in pausing activities if any causes for concern are identified.”

Removing the full inventory of waste from MSSS is expected to take many years. Once waste is removed it will be placed into modern storage facilities on the site, pending long term disposal in a geological disposal facility.

Head of programme delivery for Magnox Swarf Storage Silo, Chris Halliwell, heads up the team and explains some of the challenges they have faced. He said: “This is the culmination of decades of preparation by hundreds of people across our Sellafield Ltd and supply chain. As well as maintaining the original concrete structure of the building, we have designed and are installing purpose-built retrieval machines.

“The first of our 3 retrievals machines has now started the job which will take another 20 or so years to complete. Our teams use this machine to reach down into the compartment of the silo, grab waste from inside, and put it inside containers that have been designed and manufactured for the job.

“Eventually those metal waste boxes will be held safely inside a new highly engineered store currently being built on site. So that we can get waste out as soon as possible, we are making use of existing stores at Sellafield until the new one is ready.

“All of the waste will eventually be sent to a geological disposal facility when that becomes available. Once empty of waste, our attention will turn to decommissioning and ultimately knocking down the silo building.”