Trawsfynydd power station was built in the early 1960s and generated electricity for almost 30 years. It remains the only inland nuclear power station in the UK. Since generation stopped, the site has focused on safely managing the legacy left behind, with much of the effort centred on reducing risk and preparing the site for long term decommissioning.
After two decades of commitment, innovation and teamwork, the Higher Activity Waste (HAW) programme has now been successfully completed. This work focused on the safe management and storage of radioactive waste left behind from operations, a task that required sustained effort and careful delivery over many years.
The programme focused on the highest waste that remained on site, categorised as intermediate-level waste, a mid-range category of radioactive waste which is more active than everyday low-level waste, but not as hazardous as high-level waste.
It involved retrieving legacy material, processing it safely and placing it into secure long-term storage on site. In total, almost 2,300 individual waste packages were completed, representing a significant delivery achievement and the removal of the site’s hazards.
Rob Fletcher, CEO at Nuclear Restoration Services (NRS), said the completion of the programme marks a turning point for the site.
This is not just the end of a major programme, it is the end of an era.
Completing this work safely and successfully has allowed Trawsfynydd to move into its next phase of delivery, reducing the height of the reactors by almost half. This will create the most noticeable change to the landscape in decades.
Tom Williams, NRS Trawsfynydd Site Director added,
Bringing the HAW programme to a close is a remarkable achievement for everyone at Trawsfynydd. Its completion represents a key delivery milestone in our decommissioning mission; one we can look back on with pride whilst also looking forward with excitement to the start of our new major projects.
The final waste package has now been transferred into storage, bringing the long‑running campaign to a close. Along the way, teams developed practical and innovative ways of working to safely retrieve the waste. This included using a robotic arm to remove material from deep storage areas and specialist vacuum equipment to collect fine dust and small fragments.
Learning from this work was shared with other sites across the country, helping to improve efficiency, reduce costs and support delivery across the wider decommissioning programme.
As Trawsfynydd moves into this new phase, the end of the waste programme stands as a clear example of successful delivery, teamwork and long term commitment and a proud moment for everyone involved.
Clive Nixon, the NDA’s Chief Nuclear Strategy Officer, said
This milestone demonstrates the significant progress we are making in delivering on our mission, set on behalf of government, to safely, securely and cost effectively clean up the UK’s earliest nuclear sites, prioritising the reduction of the highest hazards and risks while protecting people, communities and the environment.
We look forward to the next phase of work, which will see the height of the reactors reduced, taking a big step towards their dismantling, as we progressively deliver on our mission to decommission the site.
It was announced in October 2025 that Costain had been appointed as principal contractor to reduce the height of the reactor buildings from around 54m to 29m. The project, valued at up to £70 million, is expected to take up to four years to deliver. At its peak, Costain is expected to employ more than 100 people to deliver the programme, creating opportunities to boost regional skills development and make a lasting contribution to the local economy.
