Sellafield Ltd is looking for specialist suppliers to help with cleaning up and decommissioning the nuclear site in Cumbria.
The work at the site, dating backing to the 1940s, has been valued at up to £1.5 billion and will be for 10 years.
Around 11,000 people work at Sellafield but it needs “external assistance” to carry out the specialist work, the firm said.
Jack DeVine, Chief Decommissioning Officer said: “To help us complete this clean-up mission, we will put in place a commercial mechanism so that we can very quickly and efficiently pull together specialist resources for decommissioning work to supplement our existing workforce.”
Last week a joint venture between infrastructure group Balfour Beatty and Cavendish Nuclear won a contract to build a £160 million nuclear decommissioning support facility at Sellafield.