A consortium consisting of French nuclear group Areva, the Washington Group and engineering company Amec has been named preferred bidder for the £22.1 billion contract to run the nuclear facility at Sellafield in Cumbria.

The group will manage the site for up to 17 years and will be responsible for cleaning up decades of waste and running Sellafield's commercial activities such as spent fuel reprocessing.

It is the first contract since the 2004 Energy Act that devolves the running of state nuclear assets to the private sector.

Stephen Henwood, chairman of the Nuclear Decommissioning Authority, which owns Sellafield, said: "The importance of achieving world-class performance throughout the Sellafield sites cannot be underestimated."

The decommissioning process began last year when four cooling towers at Calder Hall were demolished.

In 2007, Sellafield signed an agreement with nuclear services group Studsvik to ship reactive steel and fuel bottles to Sweden.