Waste package in place ahead of MSSS clearance

13 August 2018

The first shielded waste transfer package has been installed onto one of three machines at the Magnox Swarf Storage Silo (MSSS) at the Sellafield site in the UK. The machines will begin removing magnesium swarf waste from the building's 22 silo compartments from next year.

The first waste transfer package is put in place at the MSSS (Image: Sellafield Ltd)

The Magnox Swarf Storage Silo project was built in Cumbria, England in the 1960s to store waste from the UK's earliest nuclear reactors. These 16-metre deep silos were constructed to accommodate the magnesium swarf waste produced by the decanning of Magnox fuel prior to reprocessing. The swarf was stored underwater, and the first facility of six silos began operations in 1964. By 1983 a total of 22 silos had been built, but by the early 1990s wet storage of Magnox swarf was superseded by dry storage.

The MSSS closed in 2000 and has been prioritised for clean-up by the Nuclear Decommissioning Authority (NDA). Decommissioning of the MSSS is under way, but all the waste stored in the silos, including the water in which the swarf is submerged, must be removed before the building can be demolished. A robot was deployed in the MSSS silos last October to help dislodge and clear waste. The solid waste will be removed from the silos, processed and encapsulated for long-term storage.

Sellafield Ltd announced on 10 August that the first 50-tonne waste package has been safely placed onto one of the three machines that will be used to remove the swarf from the silos.

"Preparations for removing the 11,000 cubic metres of historic waste from the silos and placing them into safe, modern storage have been over twenty years in the making," the company said. "Next year three 360-tonne Silo Emptying Plant (SEP) machines will start reaching in to the silos and removing the waste with a hydraulic grab."

This waste will then be loaded into the transfer packages and transferred to the Magnox Encapsulation Plant, which has been built to receive dry Magnox swarf, encapsulate it in cement and seal it in stainless steel drums. These will then be stored on the Sellafield site until a permanent geological disposal facility is constructed.

Head of Programme for MSSS, Chris Halliwell, said: "The transfer package is the essential link in the chain to safer storage. It's a big moment to see it finally being attached to the SEP machine inside the silo. Never before have these two bits of machinery met inside the place where they'll be carrying out our biggest job in hazard reduction."

The first transfer package to enter MSSS was manufactured by Workington firm TSP Engineering and is one of nine original packages they have built and modified for Sellafield Ltd. TSP is currently competing with Cavendish Nuclear to build the next batch of 15 transfer packages.

Researched and written by World Nuclear News