Trawsfynydd nuclear power station (Atomfa Trawsfynydd) is a former Magnox nuclear power station situated in Snowdonia National Park in Gwynedd, Wales. The plant, which became operational in 1965, was the only nuclear power station in the UK to be built inland, with cooling water that was taken from the artificial Llyn Trawsfynydd reservoir which also supplies the hydro-electric Maentwrog power station. It was closed in 1991. Its ongoing decommissioning by Magnox Ltd was expected to take almost 100 years, but in 2021 the Welsh government arranged for the power station to be redeveloped using small-scale reactors. The power station, which takes its name from the nearby village of Trawsfynydd, was designed by Basil Spence. The construction, which was undertaken by a consortium involving Crompton Parkinson, International Combustion, Fairey Engineering and Richardsons Westgarth, and known as the Atomic Power Constructions (APC), began in July 1959, and both of the reactors were in operation by March 1965, with the station opening fully in October 1968, at a cost of £103 million. It had two Magnox reactors producing 470 megawatts (MW) in total. The reactors were supplied by APC and the turbines by Richardsons Westgarth. The civil engineering work was undertaken by Holland, Hannen & Cubitts and Trollope & Colls. The architectural consultant for the buildings was Sir Basil Spence and the landscape architect was Sylvia Crowe. The setting for the power station which Crowe developed is designated Grade II* on the Cadw/ICOMOS Register of Parks and Gardens of Special Historic Interest in Wales. Nuclear flasks were transported to Trawsfynydd on a section of the former Bala to Blaenau Ffestiniog railway that had been closed in January 1961. A single track was restored northwards with an entirely new line through the centre of Blaenau Ffestiniog that connected to the Conwy Valley branch. In 1963-64, a "Goliath" gantry crane was installed over sidings about east of the power station.