Hazadous nuclear waste will be taken out of Cumbria’s Sellafield plant in massive stainless steel containers which have just come off the production line.

The highly-engineered 1.3 tonne boxes are playing a major part in the decommissioning of the West Cumbrian plant as the waste is moved into safe storage for centuries to come.

Darchem Engineering, of Stockton on Tees, and Metalcraft in Cambridgeshire have finished manufacturing the first batch of containers.

A total of 2,200 of the boxes will be needed to hold legacy waste from one of the world’s oldest nuclear stores, Sellafield’s Pile Fuel Cladding Silo.

Sellafield bosses have described it as the most significant step yet towards getting the waste out of the facility next year.

Glenn McCracken, head of decommissioning for Sellafield Ltd, said: "We’re on the brink of seeing waste retrievals starting from our two legacy silos and expect to start getting the waste out of both facilities next year.

"That will be a massive moment, but before getting the waste out, we need to be sure that it has got somewhere safe to go to.

"That means having enough boxes ready to be filled and having the confidence that a conveyor belt of production will be delivering a steady stream of them."

Mr McCracken said the site was moving into a 100-year programme of environmental remediation, which means decommissioning old facilities and moving the waste into safe containment for centuries to come.

The containers are engineered to allow any hydrogen to be safely vented with the boxes needed as the contents of the silo are emptied over the 10 to 12 years.

This means both companies will be making the containers at the rate of two a week.

Designed to last at least 500 years to see them through their journey into a geological disposal facility, the boxes are made from duplex steel, which is stronger and more resistant to corrosion than typical stainless steel.

The highest hazard plant on the site, the Magnox Swarf Storage Silo, will need an estimated 15,000 boxes to store the waste being taken out of the legacy silo over the next two decades.