Dec. 2, 1942:  The first man-made controlled nuclear reaction takes place, underneath the grandstand of the University of Chicago’s football grandstand.

Dec. 2, 1957:  The first commercial nuclear power plant goes online, in Shippingport, PA.

Wired has an article, here:  http://www.wired.com/science/discoveries/news/2008/12/dayintech_1202

One interesting piece of historical nomenclature is that, at the Chicago experiment, there was a staffer prepared to cut a rope with an axe, to drop graphite rods into the reactor and stop the reaction.  This acronym, SCRAM, for Safety Control Rod Ax-Man, is still used for the emergency shutdown systems in modern reactors.