B Reactor can take a tour of the reactor by advance reservation. The reactor was designed and built by E. I. du Pont de Nemours and Company based on experimental designs tested by Enrico Fermi at the University of Chicago, and tests from the X-10 Graphite Reactor at Oak Ridge National Laboratory. It was designed to operate at 250 megawatts (thermal). The reactor occupies a footprint of (about and is tall, occupying a volume of . The reactor core itself consisted of a graphite box measuring occupying a volume of and weighing . It was penetrated horizontally through its entire length by
Enrico Fermi Y at Los Alamos, New Mexico. Arriving in September, Fermi was appointed an associate director of the laboratory, with broad responsibility for nuclear and theoretical physics, and was placed in charge of F Division, which was named after him. F Division had four branches: F-1 Super and General Theory under Teller, which investigated the "Super" (thermonuclear) bomb; F-2 Water Boiler under L. D. P. King, which looked after the "water boiler" aqueous homogeneous research reactor; F-3 Super Experimentation under Egon Bretscher; and F-4 Fission Studies under Anderson. Fermi observed the Trinity test on 16 July 1945, and conducted an experiment