Enrico Fermi of a self-sustaining nuclear reaction were unknown, so it seemed inadvisable to build the first nuclear reactor on the University of Chicago campus in the middle of the city. Compton found a location in the Argonne Woods Forest Preserve, about from Chicago. Stone & Webster was contracted to develop the site, but the work was halted by an industrial dispute. Fermi then persuaded Compton that he could build the reactor in the squash court under the stands of the University of Chicago's Stagg Field. Construction of the pile began on 6 November 1942, and Chicago Pile-1 went critical on 2
Enrico Fermi down once more a few hours later. The problem was traced to neutron poisoning from xenon-135, a fission product with a half-life of 9.2 hours. DuPont had deviated from the Metallurgical Laboratory's original design in which the reactor had 1,500 tubes arranged in a circle, and had added 504 tubes to fill in the corners. The scientists had originally considered this over-engineering a waste of time and money, but Fermi realized that if all 2,004 tubes were loaded, the reactor could reach the required power level and efficiently produce plutonium. In mid-1944, Robert Oppenheimer persuaded Fermi to join his Project