Profile America — Monday, December 2nd. One of the most important technological breakthroughs was made on this date in 1942, one that would change the course of world history. At the University of Chicago, a group of scientists led by physicist Enrico Fermi succeeded in producing the first controlled, self-sustaining nuclear chain reaction. This first simple reactor, built in great secrecy under the stands of the university's football stadium, helped provide the knowledge that led to the development of the first atomic bombs less than three years later. Today, reactors power most U.S. aircraft carriers and submarines. And there are 104 nuclear power plants, generating over 800 billion kilowatt hours, or one-fifth of the electricity consumed in the U.S. You can find more facts about America from the U.S. Census Bureau on the Web at www.census.gov>.