The UK's Nuclear Decommissioning Authority (NDA) has taken ownership of Sellafield Ltd, the company responsible for cleanup operations at the Sellafield site in the UK. It became a wholly owned subsidiary of NDA on 1 April, a statement on the UK government's website says. The new ownership structure aims to boost the efficiency with which Sellafield Ltd delivers its "mission", the statement said. Previously, Sellafield Ltd was owned by the Nuclear Management Partners group, bringing together private sector firms such as AECOM, Amec Foster Wheeler and Areva. According to this arrangement, Sellafield Ltd carried out its decommissioning works under contract to the NDA. The Sellafield site comprises a range of nuclear installations, including redundant facilities associated with early defence work as well as operating installations associated with the Magnox reprocessing programme, the thermal oxide reprocessing plant (Thorp), the Sellafield mixed oxide fuel plant and a range of waste treatment units. On-site activities began in the early 1950s making plutonium for nuclear weapons, and later that decade Sellafield became the location of Calder Hall, the world's first commercial nuclear power station.