A consortium of Areva, the French nuclear group, Washington Group of the US and Amec, the UK engineering company, was on Friday named preferred bidder for the contract to manage the clean-up of the UK’s most radioactive site.

The contract to run the Sellafield complex in Cumbria, north-west England, is for a term of up to 17 years and will be worth around £1.3bn a year. The successful bidder is expected to earn around £50m of profit a year from the contract, although this will vary depending on hitting performance and efficiency targets.