Wikipedia:Today's featured article/September 5, 2018

The Metallurgical Laboratory at the University of Chicago in the US state of Illinois was established during World War II to research the chemistry and metallurgy of the newly discovered element plutonium, as part of the Allied Manhattan Project to build an atomic bomb. It developed chemical processes to separate plutonium, and created the first weighable sample. The lab produced the first controlled nuclear chain reaction in the Chicago Pile-1 nuclear reactor, which was constructed under the stands of the university's old football stadium, Stagg Field. Another reactor, Chicago Pile-3, the first reactor to use heavy water as a neutron moderator, was built in early 1944. The Metallurgical Laboratory also designed the X-10 Graphite Reactor at the Clinton Engineer Works in Oak Ridge, Tennessee, and the B Reactor at the Hanford Engineer Works. It became the first of the national laboratories, the Argonne National Laboratory, on 1 July 1946.