Calder Hall Nuclear Power Station is a former Magnox nuclear power station at Sellafield in Cumbria in North West England. Calder Hall was the first full-scale nuclear power station to enter operation in the West, and was the sister plant to the Chapelcross plant in Scotland. Both were commissioned and originally operated by the United Kingdom Atomic Energy Authority. The primary purpose of both plants was to produce weapons-grade plutonium for the UK's nuclear weapons programme, but they also generated electrical power for the National Grid.