Plutonium is primarily produced in nuclear reactors through a process of neutron capture and radioactive decay of uranium-238. This process, where uranium-238 absorbs a neutron, produces heat which is transformed into steam that is used to drive a generator which produces electricity and during the process the uranium-238 is transformed into plutonium-239, which is then used in nuclear weapons.

PLUTONIUM PRODUCTION

Processes

• Fuel and Target Fabrication

• Reactor Operations

• Chemical Separation

• Met Lab and Oak Ridge Hazards and Wastes

• Hanford Hazards and Wastes

• See: https://www.osti.gov/opennet/manhattan-project-history/Processes/PlutoniumProduction/plutonium.html

Uranium isotope separation and plutonium production provided the two paths that led to an atomic bomb. Not existing naturally in any significant quantities, plutonium had to be made. The industrial-scale production of plutonium required nuclear reactors, initially called piles. Because natural uranium provided the fuel for the reactors, the production of plutonium bomb cores depended on the mining, milling, and refining of uranium ore as much as the uranium bomb designs did. The refining process produced uranium metal for the plutonium process. The metal was fabricated into fuel slugs that, for the production reactors, were sealed in aluminum cans. The uranium-235 in the fuel produced neutrons that sustained the chain reaction in the reactor, while the uranium-238 in the fuel captured neutrons to produce plutonium.

The world’s first reactor CP-1 was designed and built by the Metallurgical Laboratory located at the University of Chicago. This experimental reactor investigated the basic physics of chain reactions and uranium. The DuPont Corporation built a much larger experimental air-cooled production reactor at the Oak Ridge X-10 site. The X-10 reactor supplied the Los Alamos laboratory with the first significant amounts of plutonium, as well as providing invaluable experience for engineers, technicians, reactor operators, and safety officials. DuPont built and operated three full-scale water-cooled production reactors at the Hanford site. Consisting of a 28- by 36-foot, 1,200-ton graphite cylinder lying on its side, the reactors were penetrated through their entire length horizontally by 2,004 aluminum tubes. Two hundred tons of uranium slugs were loaded from the face of the reactor into the tubes. After exposure to the chain reaction within the reactor, the now highly radioactive slugs were pushed through the reactor and dropped into water pools directly behind the reactors. Sustained reactor operations left within the uranium slugs a mixture of plutonium, uranium, and other elements. To build a working plutonium bomb, the plutonium needed to be chemically separated from the other materials. DuPont selected a process developed by the Met Lab in which the slugs were dissolved in acid, and then the plutonium was precipitated out by adding bismuth phosphate. The process first was used on an industrial scale at the X-10 chemical separation plant, which was located next to the X-10 reactor. DuPont built massive, scaled-up versions of the X-10 plant at Hanford’s two chemical separation sites (200-West and 200-East) located almost ten miles south of the reactors.

The reactors produced tremendous amounts of radioactivity. Some of the radioactivity was released to the environment up stacks or in cooling water. The vast majority of the radioactivity was contained in the wastes produced during chemical separation. Wastes containing the highest levels of radioactivity were stored in tanks. Hazards and wastes generated at CP-1 and the X-10 site were considerably less than those at Hanford, which accounted for almost 99 percent of the radioactivity produced by Manhattan Project activities.