In 1942, the Metallurgical Laboratory at the University of Chicago was building the worlds first nuclear reactor called Chicago Pile-1' as part of the Manhattan Project. This would have required an enormous number of graphite blocks and uranium pellets. At the time, there was a limited source of pure uranium. Frank Spedding of Iowa State University was able to produce only two short tons of pure uranium. However, a larger quantity of additional uranium metal was required for the pile to go critical.
Around that time, Westinghouse Lamp Plant was able to supply a small amount of pure uranium metal. By 1941, there was an order for the uranium metal of 10 kilograms which was considered an enormous amount. The plant ramped up the production using makeshift equipment including metal garbage cans from a local market to use in the process. The order was fulfilled within a couple of months. By early 1942, there was another order from Arthur H. Compton of the Metallurgical Laboratory for three short tons of the uranium metal for the Chicago Pile-1.
The project was done in secrecy by not revealing any connection of the work there to the ongoing research on the nuclear reaction. To avoid leaking of information about the project at the plant, it was covered with the program called Tuballoy which was the codename for uranium in programs related to the Manhattan Project, taken from the British atomic weapons effort "Tube Alloys" which had been folded into Manhattan. Due to inadequate equipment and space, the refinement process was done in an ad hoc fashion having some operations done in the basement and some on the roof on a building at the plant. To maintain the confidentiality of the program, many workers who worked on the chemical processes were not familiar with it. Most of them did not know that their work was related to the creation of an atomic weapon.
Although the material and the processes were kept secret, the workers there knew they worked as part of the World War II efforts. They were led to believe that they worked on making conventional bombs. During the height of the production in 1942, there was a war production drive at the plant under the auspices of the labor-management committee to increase its production and warned workers against sabotage. The streets at the plant were renamed to MacArthur Avenue and MacArthur Plaza to promote patriotism.
Finally, the required amount of uranium metal was delivered to Chicago by the Army with containers clearly marked "URANIUM". The Chicago Pile-1 had gone to self-sustaining reaction on December 2, 1942, with the majority of uranium metal from the plant. After that, the plant continued to play a major role in supplying the uranium metal for the Manhattan Project until October 1943 when a better and more economical process was done elsewhere. During the contract, the plant produced 69 short tons of uranium metal in total.