 In the early afternoon of December 20, 1951, Argonne director Walter Zinn and fifteen other Argonne staff members witnessed a row of four light bulbs light up in a nondescript brick building in the eastern Idaho desert.Electricity from a generator connected to Experimental Breeder Reactor I (EBR-I) flowed through them.This was the first time that a usable amount of electrical power had ever been generated from nuclear fission.