Surreal comparison, courtesy of British Nuclear Group
The British Nuclear Group works in decommissioning nuclear reactors. They have a little blurb for each of the reactors they're currently working on and soon to work on. These include an idea of how much power the plants produced, usually specified in terawatt hours or 'can power Bristol'-type comparisons. Except for Calder Hall. Calder Hall, the world's first nuclear power plant (a rather bijou Soviet one may have been connected to a grid a year earlier, but Calder Hall was certainly the first of any significant size), can apparently power a three-bar electric fire for 2.85 million years. So now you know.