The handover follows Costain being awarded a key contract in October 2025 to carry out the reactor height reduction at Trawsfynydd. This project, one of the most significant currently underway across the NDA estate, aims to reduce the height of both reactor buildings by nearly half. The work is expected to transform the site's skyline and provide valuable learning for future decommissioning projects throughout the UK.
Beyond the immediate decommissioning goals, the project is set to deliver wider benefits to the region. It is anticipated to support employment, skills development, apprenticeships, and create opportunities for local businesses and communities. At its peak, the programme is expected to generate over 100 jobs with Costain, contributing to the strengthening of the local supply chain and the regional economy.
Following the handover, both the NDA and Costain have successfully completed a crucial project review. This confirmed that plans and delivery arrangements are progressing as anticipated, an important step towards future demolition works.
With the handover now finalised, Costain has assumed control of the reactor buildings area, enabling the commencement of on-site delivery for the reactor height reduction project. This transition signifies the move from extensive planning and preparation into the active delivery phase.
For the existing Trawsfynydd workforce, this handover represents the successful conclusion of a major preparatory phase and highlights the progress made in advancing one of the UK's most significant decommissioning projects.
Early activities, including scaffolding, hoist installation, and electrical infrastructure works, are already being supported by a crane that has arrived on site. The most visible stage of the project is anticipated to commence later this year with the arrival of large crawler cranes, followed in early 2027 by the erection of two large tower cranes within the reactor buildings for the deconstruction process.
“"Reaching this milestone reflects years of planning, preparation and collaboration for our dedicated workforce and supply chain partners. I’d like to thank everyone whose hard work and commitment has helped us get to this point."
“"As well as delivering an important step forward in decommissioning, the project will create opportunities for local people and businesses, helping ensure benefits are felt beyond the site boundary."
“"Trawsfynydd has an important role as one of NRS’s lead and learn sites. The experience gained through this project will help inform future decommissioning programmes across the wider NRS estate and support the development of skills, knowledge and best practice."
