The Manhattan Project: Making the Atomic Bomb

The Metallurgical Laboratory

One of the most important branches of the far flung Manhattan Project was the Metallurgical Laboratory (Met Lab) in Chicago, which was counted on to design a production pile for plutonium. Here again the job was to design equipment for a technology that was not well understood even in the laboratory. The Fermi pile, important as it was historically, provided little technical guidance other than to suggest a lattice arrangement of graphite and uranium. Any pile producing more power than the few watts generated in Fermi's famous experiment would require elaborate controls, radiation shielding, and a cooling system. These engineering features would all contribute to a reduction in neutron multiplication (neutron multiplication being represented by k); so it was imperative to determine which pile design would be safe and controllable and still have a k high enough to sustain an ongoing reaction. ³⁵

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