Overview: Keeley Donovan meets the people working at Britain's biggest operational nuclear site at Heysham on the Lancashire coast. Heysham 1 and Heysham 2 power stations make enough electricity to power more than four million homes. Keeley follows engineers as they undertake a huge maintenance programme called an outage. But with Britain in lockdown during the coronavirus pandemic, will engineers be able to get one of the reactors back on line to provide much-needed energy to the nation?