100 AREA: PLUTONIUM PRODUCTION REACTORS

F Reactor Plutonium Production Complex at Hanford, 1945

(1944 - )
Places > Hanford Engineer Works

The Army and the DuPont Corporation located the three water-cooled production reactors (piles) at the points of a triangle formed by a bend in the Columbia River near White Bluffs. Designated as the 100 B (West), 100 D (North), and 100 F (East) Pile Areas, each area was about 1 mile square and, for reasons of safety, about 6 miles apart.

Construction forces could not begin work on the reactors until DuPont released the basic design drawings. In the meantime, however, much work was done on the support facilities required for each reactor. On the basis that each reactor would produce 250,000 kilowatts of heat, the DuPont engineers calculated the size of the facilities necessary to bring cooling water to the piles. For all three units, water consumption would approach that of a city of one million persons. The design of the water supply for each of the reactor areas resembled that of a large municipal plant. Each would have a river pump house, large storage and settling basins, a filtration plant, huge motor-driven pumps for delivering water to the face of the reactor, and facilities for emergency cooling in the case of a power failure. Construction on the water-cooling facilities in the B-Reactor area began on August 27, 1943.

DuPont released the reactor design drawings on October 4, 1943. Similar to the X-10 Graphite Reactor at Oak Ridge in terms of loading and unloading fuel, the Hanford production reactors would be built on a much larger scale. Whereas the X-10 had an initial design output of 1,000 kilowatts, the Hanford reactors were designed to operate at 250,000 kilowatts. Consisting of a 28- by 36-foot, 1,200-ton graphite cylinder lying on its side, the production reactors were penetrated through their entire length horizontally by 2,004 aluminum tubes. Two hundred tons of uranium slugs the size of rolls of quarters and sealed in aluminum cans went into the tubes. Cooling water was pumped through the aluminum tubes around the uranium slugs at the rate of 30,000 gallons per minute.

On October 10, DuPont engineers drove the first stakes marking the location of the B-Reactor pile building. The area immediately under the reactor was excavated and carefully load-tested. Once the foundations were fixed, work gangs began to lay the first of 390 tons of structural steel, 17,400 cubic yards of concrete, 50,000 concrete blocks, and 71,000 concrete bricks that went into the pile building. Starting with the foundations for the reactor and the deep-water basins behind it where the irradiated slugs would be collected after discharge, the work crews were well above ground by the end of the year. By early 1944, a windowless concrete monolith towered 120 feet above the desert. Assembly of the pile itself began in February. The cast-iron base and the thermal and biological shields around the pile were completed by mid-May. It took another month to lay the graphite blocks within the shield and install the top shield and two months to wire and pipe the pile and connect it to various monitoring and control devices.

By the middle of August 1944, B Reactor was complete. The F and D reactor complexes, essentially identical to that of B Reactor, were completed in late November 1944 and early February 1945 respectively. B Reactor went critical on September 27, 1944, with the first irradiated slugs discharged on December 25. The three reactors produced sufficient plutonium by August 1945 for the Trinity device and two implosion bombs.

The three Manhattan Project production reactors continued in operation well into the Cold War. The B Reactor was shut down March 1946 and placed on standby, but it resumed operation in July 1948 and continued in production until February 1968. The tritium used in the first hydrogen bomb test of November 1952 was produced in the B Reactor. The D and F Reactors were not retired June 1967 and June 1965, respectively. The D and F Reactor buildings have been severely cut back and essentially entombed for environmental and safety reasons. Nearly all support buildings at the three reactor sites have been demolished. The B Reactor was declared a National Historic Landmark in August 2008. The interior of the B Reactor building and the face of the reactor are currently accessible on a limited basis.

Sources and notes for this page

The text for this page is original to the Department of Energy's Office of History and Heritage Resources. Major sources consulted include the following. Richard G. Hewlett and Oscar E. Anderson, Jr., The New World, 1939-1946: Volume I, A History of the United States Atomic Energy Commission (Washington: U.S. Atomic Energy Commission, 1972), and Manhattan District History, Book IV - Pile Project, Volume 5 - Construction, and Volume 6 - Operation. Click here for more information on the aerial photograph of Hanford. The photograph of the face of B Reactor is reproduced from the History Office publication: The Signature Facilities of the Manhattan Project (Washington: History Division, Department of Energy, 2001), 7.