 Walter Henry Zinn designed and built several new reactors, including one that produced sufficient electricity to illuminate four what?
200-watt light bulbs.
Title: Experimental Breeder Reactor I
Passage: Experimental Breeder Reactor I (EBR-I) is a decommissioned research reactor and U.S. National Historic Landmark located in the desert about 18 mi southeast of Arco, Idaho.  At 1:50 p.m. on December 20, 1951, it became one of the world's first electricity-generating nuclear power plants when it produced sufficient electricity to illuminate four 200-watt light bulbs. Electricity had earlier been generated by a nuclear reactor on September 3, 1948 at the X-10 Graphite Reactor in Oak Ridge, Tennessee.  EBR-I subsequently generated sufficient electricity to power its building, and continued to be used for experimental purposes until it was decommissioned in 1964.  The Museum is open for visitors from Memorial Day to Labor Day.
Title: Walter Zinn
Passage: Walter Henry Zinn (December 10, 1906 – February 14, 2000) was a nuclear physicist who was the first director of the Argonne National Laboratory from 1946 to 1956.  He worked at the Manhattan Project's Metallurgical Laboratory during World War II, and supervised the construction of Chicago Pile-1, the world’s first nuclear reactor, which went critical on December 2, 1942, at the University of Chicago.  At Argonne he designed and built several new reactors, including Experimental Breeder Reactor I, the first nuclear reactor to produce electric power, which went live on December 20, 1951.
Title: United States naval reactors
Passage: United States naval reactors are nuclear reactors used by the United States Navy aboard certain ships to generate the steam used to produce power for propulsion, electric power, catapulting airplanes in aircraft carriers, and a few more minor uses.  Such Naval nuclear reactors have a complete power plant associated with them.  All U.S. Navy submarines and supercarriers built since 1975 are nuclear-powered by such reactors.  There are no commissioned conventional (non-nuclear) submarines or aircraft carriers left in the U.S. Navy, since the last conventional carrier, USS "Kitty Hawk" , was decommissioned in May 2009.  The U.S. Navy had nine nuclear-powered cruisers with such reactors also, but they have since been decommissioned.  Reactors are designed by a variety of contractors, then developed and tested at one of several government (Department of Energy)-owned and prime contractor -operated facilities.  These facilities include Bettis Atomic Power Laboratory in West Mifflin, PA and its associated Naval Reactors Facility in Idaho, and Knolls Atomic Power Laboratory in Niskayuna, NY and its associated Kesselring site in West Milton, NY, all under the management of the office of Naval Reactors.  Sometimes there were full-scale nuclear-powered prototype plants built at the Naval Reactors Facility, Kesselring, and Windsor (in CT) to test the nuclear plants, which were operated for years to train nuclear-qualified sailors.
Experimental Breeder Reactor I Walter Zinn