The world's first commercial nuclear power station opened

On October 17, 1956, Queen Elizabeth II opened Calder Hall, in Cumbria, England — the first nuclear power station anywhere to feed electricity into a national grid on a commercial scale. With theatrical timing, the plant was already quietly powering the National Grid before the Queen even pulled the lever.

Calder Hall was never purely civilian. Its four Magnox reactors were designed chiefly to produce plutonium for Britain’s atomic weapons program, with electricity as a profitable byproduct. Each reactor generated tens of megawatts, and nearby Workington is often cited as the first town lit by nuclear power.

It ran for 47 years, closing in 2003 after outlasting nearly every prediction.

The station’s dual purpose captured the era’s tangled ambitions: the same technology promised both cheap electricity and the bomb. Decommissioning continues at the Sellafield site today, decades after that ceremonial switch.