Office for Nuclear Regulation



  • Operator/Licensee: Magnox Limited
  • Owner: Nuclear Decommissioning Authority
  • Type of site: Decommissioning
  • Location: Gwynedd, Wales

Magnox website

Trawsfynydd - Copyright Magnox Limited


Trawsfynydd is a twin reactor decommissioning power station located on a 15.5 hectare site in Snowdonia National Park link to external website in Gwynedd link to external website, Wales. The plant, which became operational in 1965, was the only nuclear power station in the UK to be built inland.

Construction commenced in 1959, with both reactors operational by 1965. Generation ceased in 1991 and defueling was completed by 1997 with fuel elements removed from the site and transported to Sellafield for reprocessing.

The Nuclear Decommissioning Authority’s (NDA) strategic aim is to deliver site end-states as soon as reasonably practicable. On 30 July 2020 the NDA announced at the Trawsfynydd site stakeholder public meeting 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. This change in strategy means that Magnox Limited’s Trawsfynydd site will undertake continuous planned decommissioning activities, including demolitions, to progressively reduce risk and hazards instead of its previous strategy of preparing the site to enter a care and maintenance phase.