Oak Ridge National Laboratory is an American multiprogram science and technology national laboratory sponsored by the U.S. Department of Energy and administered, managed, and operated by UT–Battelle as a federally funded research and development center under a contract with the DOE. Established in 1942, ORNL is the largest science and energy national laboratory in the Department of Energy system and third largest by annual budget. ORNL is located in the Roane County section of the city of Oak Ridge, Tennessee. ORNL's scientific programs focus on materials, neutron science, energy, high-performance computing, systems biology and national security., ORNL partners with the state of Tennessee, universities and industries, to solve challenges in energy, advanced materials, manufacturing, security and physics., The laboratory has several of the world's top supercomputers; among these, Summit is ranked by the TOP500 as the world's second-most powerful supercomputer. The lab also is a leading neutron-science and nuclear-energy research facility that includes the Spallation Neutron Source and High Flux Isotope Reactor. ORNL hosts all of the following:, Oak Ridge National Laboratory is managed by UT–Battelle, a limited liability partnership between the University of Tennessee and the Battelle Memorial Institute, formed in 2000 for that purpose. The annual budget is US$1.65 billion, 80% of which is from the Department of Energy; the remainder is from various sources paying for use of the facilities. As of 2012 there are 4,400 staff working at ORNL, 1,600 of whom are directly conducting research, and an additional 3,000 guest researchers annually., There are five campuses on the Department of Energy's Oak Ridge reservation; the National Laboratory, the Y-12 National Security Complex, the East Tennessee Technology Park , the Oak Ridge Institute for Science and Education, and the developing Oak Ridge Science and Technology Park, although the four other facilities are unrelated to the National Laboratory. The total area of the reservation 150 square kilometres of which the lab takes up 18 square kilometres ., The city of Oak Ridge was established by the Army Corps of Engineers as part of the Clinton Engineer Works in 1942 on isolated farm land as part of the Manhattan Project., During the war, advanced research for the government was managed at the site by the University of Chicago's Metallurgical Laboratory. In 1943, construction of the "Clinton Laboratories" was completed, later renamed to "Oak Ridge National Laboratory". The site was chosen for the X-10 Graphite Reactor, used to show that plutonium can be created from enriched uranium. Enrico Fermi and his colleagues developed the world's second self-sustaining nuclear reactor after Fermi's previous experiment, the Chicago Pile-1. The X-10 was the first reactor designed for continuous operation. After the end of World War II the demand for weapons-grade plutonium fell and the reactor and the laboratory's 1000 employees were no longer involved in nuclear weapons. Instead, it was used for scientific research. In 1946 the first medical isotopes were produced in the X-10 reactor, and by 1950 almost 20,000 samples had been shipped to various hospitals. As the demand for military science had fallen dramatically, the future of the lab was uncertain. Management of the lab was contracted by the US government to Monsanto; however, they withdrew in 1947. The University of Chicago re-assumed responsibility, until in December 1947, when Union Carbide and Carbon Co., which already operated two other facilities at Oak Ridge, took control of the laboratory. Alvin Weinberg was named Director of Research, ORNL, and in 1955 Director of the Laboratory.