Costain, Hochtief UK and Morgan Sindall have won contracts with a total value of up to £2.9bn to provide non-nuclear infrastructure works on the Sellafield decommissioning programme in Cumbria.
The three companies will be part of a long-term arrangement called the Infrastructure Delivery Partnership (IDP).
The partnership will deliver projects and tasks to support essential services at Sellafield like electricity distribution, water, road and rail networks, bridges, foundations and security installations
The contracts will be for an initial 9 years with an option for a further six years, through to 2040. The work is split into three lots.
Costain will deliver utilities upgrades under a contract worth up to £1bn. As part of its role, it will complete detailed design and all procurement, installation, construction, commissioning and handover activities.
Hochtief UK Construction will deliver civil works under a contract worth up to £595M. It will carry out design, engineering, and delivery of civil infrastructure works in support of nuclear operations and decommissioning in collaboration with Sellafield and its partners.
Morgan Sindall Infrastructure will deliver electrical distribution. It will lead on maintaining and upgrading the Sellafield site’s electrical network, with support from its design partners Baker Hicks and GHD.
Sellafield Ltd has said that all IDP delivery partners, including Costain and Hochtief, could be expected to undertake ground engineering or geotechnical activities as part of their contracts, subject to a work demand from their customers.
Costain chief executive officer Alex Vaughan commented: “This new contract award with Sellafield, with whom we have been working with since 2005, is testament to our strategy of developing long-term relationships with tier 1 customers, building strong and collaborative partnerships, broadening our service offering, and maintaining consistency and continuity of workflows.”
Hochtief CEO Juan Santamaría Cases said: “Together with Sellafield and its delivery partners, we have secured this strategic, long-term partnership. The award builds on Hochtief’s expanding portfolio of long-term delivery contracts with globally significant clients across the nuclear and infrastructure sectors.”
Morgan Sindall Infrastructure managing director Simon Smith said: “We have been delivering in West Cumbria for over 15 years, and we are delighted to build on this further with the award of the Infrastructure Delivery Partnership.”
The site close to Seascale in Cumbria is the birthplace of the UK nuclear industry. It is now one of the country’s largest infrastructure projects, given the various decommissioning projects that are underway there.
The site is owned by the Nuclear Decommissioning Authority (NDA) which is a non-departmental public body of the UK government. According to the NDA, the site processes and stores more radioactive material per square metre than any other site in Europe.
There have been various other major recent infrastructure contract awards on Sellafield.
In 2023, Keltbray won a £17M contract to provide a development platform and supporting infrastructure within the Cumbrian nuclear plant’s intermediate level waste east zone.
The same year, Sir Robert McAlpine won a £1bn framework agreement to provide groundworks and concrete structures for construction projects at the site.
In June 2025, the House of Commons Committee of Public Accounts reported that the estimated cost to completely decommission Sellafield in 100 years’ time had increased to £136bn, up from £114bn in March 2019.