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Trawsfynydd takes next step towards reactor height reduction

Neel Madsen Editor, Demolition & Recycling International

12 October 2026

Nuclear Restoration Services (NRS) has formally handed over the reactor buildings area at Trawsfynydd nuclear power station in Wales to Costain, allowing the next stage of reactor height reduction to proceed.

Members of the project looking out across the Trawsfynydd reactor buildings (Image: NRS)

Trawsfynydd nuclear power station, located in Eryri (Snowdonia) National Park, in Gwynedd, northwest Wales, began generating electricity in 1965 and operated for 26 years before closing in 1991.

Decommissioning has been underway since then, with the current programme focused on reducing the height of its two reactor buildings by nearly half, making it one of the most significant visible changes in decades.

Costain was awarded the contract in October 2025, and the programme is expected to create more than 100 jobs.

The project is one of the most significant programmes currently underway across the NRS estate and will generate valuable learning that can be applied to future decommissioning projects across the UK, said the NRS.

In addition, the project will bring wider benefits to the region, supporting employment, skills development, apprenticeships, and opportunities for local businesses and communities.

Following the handover, NRS and Costain have also completed a review of the project, confirming that plans and delivery arrangements are progressing as expected.

This is described as “an important step” in allowing the programme to move forward towards future demolition works.

A crane has already arrived on site to support a series of early activities, including scaffolding, hoist installation and electrical infrastructure works.

The most visible stage of the project is expected to begin later this year when large crawler cranes will be introduced.

They will be followed in early 2027 by the erection of two large tower cranes within the reactor buildings.

NRS Trawsfynydd site director Tom Williams commented, “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.”