Decommissioning milestone reached at Trawsfynydd

The 392 MWe Trawsfynydd Magnox nuclear power plant - the only inland nuclear power station in the UK - began operation in 1965 and was retired in 1991, with defueling completed by 1997. 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. In July 2020, the Nuclear Decommissioning Authority (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.

NDA subsidiary Nuclear Restoration Services (NRS) has now announced the completion of the Higher Activity Waste (HAW) programme. This work, which took 20 years to complete, focused on the safe management and storage of radioactive waste left behind from operations. 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.

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.

NRS said 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.

"This is not just the end of a major programme, it is the end of an era," said NRS CEO Rob Fletcher. "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."

NRS Trawsfynydd Site Director Tom Williams 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."

In October last year, infrastructure solutions company Costain was awarded a GBP70 million (USD94 million) contract to reduce the height of the two reactor buildings at Trawsfynydd from about 54 metres to 25 metres. That project is expected to take up to four years to be completed.