Costain to reduce height of Trawsfynydd reactor buildings

The contract was awarded by Nuclear Restoration Services (NRS), a subsidiary of the Nuclear Decommissioning Authority (NDA). Set to begin later this year, the project will reshape the site's iconic skyline through the partial removal of the upper sections of both reactor buildings, lowering them from about 54 metres to 25 metres.

The work will recover about 15,000 cubic metres of concrete and brickwork and remove about 10 overhead cranes, including two which weigh more than a Boeing 747.

Costain previously delivered enabling works at Trawsfynydd to facilitate the decommissioning process, including the installation of a new capping roof on both the reactor buildings, major de-planting of the primary boiler sections, and rerouting of electrical supplies.

The company will also deliver civils and remedial works to ensure that the buildings are in a safe and stable condition for the commencement of subsequent decommissioning activity on the site.

The programme is expected to take around four years.

Costain is also working with NRS on a six-year decommissioning programme across 11 UK sites, and delivering decommission and asset care work for Sellafield as part of the Decommissioning Delivery Partnership.

"This is a pivotal moment for Trawsfynydd," said NRS CEO Rob Fletcher. "After years of careful planning and preparation, we're now moving into the delivery phase of one of the most complex and ambitious decommissioning projects in the UK. We're delighted to be working with our supply chain partners to shape this next stage in the site's journey, ensuring the work is undertaken safely, securely and sustainably for all our futures."

NDA group CEO David Peattie added: "This is a tangible step forward in one of the most significant projects in the NDA group's portfolio and really embodies our commitment to delivering on a safer, cleaner future for generations to come. Reduction of the reactor buildings will not only advance our mission but also create first-of-its-kind opportunities for Wales, showcasing innovation and leadership in nuclear decommissioning."

Sam White, managing director, natural resources at Costain, said: "Whether it's designing the infrastructure that will produce the next generation of advanced nuclear fuel, plant optimisation or managing large-scale decommissioning programmes, Costain has decades of experience delivering predictable, best-in class solutions across the entire nuclear energy lifecycle.

"This work is all part of creating a sustainable future, and we're looking forward to deepening our relationship with NRS and working collaboratively with our local supply chain to complete this complex decommissioning project to the highest safety and quality standards."

The 392 MWe Trawsfynydd Magnox nuclear power plant began operation in 1965 and was retired in 1991, with defueling completed by 1997. In July 2020, the NDA announced its intention to pursue a rolling programme of decommissioning aimed at accelerating Magnox reactor sites decommissioning with Trawsfynydd identified as the 'lead and learn' site.