The B Reactor was the first large scale nuclear reactor ever built in the world. In was constructed in 1943-44 as part of the Manhattan Project in order to produce plutonium for nuclear weapons. The B Reactor (along with D Reactor and F Reactor) provided the plutonium 239 used in the first atomic device ever exploded on July 16, 1945, known as the Trinity Test. It also produced the plutonium-239 used in the bomb dropped on Nagasaki on August 9, 1945. This was first and only plutonium weapon used in warfare. The B Reactor produced fissionable material from 1944 until its deactivation in 1968.
The B Reactor is an all water cooled, graphite-moderated reactor. It provided the basic design used in two Hanford reactors (D and F) built during the war and five Hanford reactors (DR, H, C, KW, and KE) built from 1947 to 1955. These reactors produced all the plutonium used in U.S. nuclear weapons, until 1952 when the Savannah River, S.C., plant came on line.
The B Reactor has no moving parts. During operations the only sounds it would make would be the millions of gallons of water from the Columbia River being pumped in to cool it down. The amount of people needed to actually operate the B Reactor it was small. A typical crew was less than twenty people.
The design for the B Reactor came from the Metallurgical Laboratory in Chicago. Their design was based on the original pile built by Enrico Fermi at the University of Chicago. Fermi's pile was the first ever self-sustaining chain reaction which occurred in December 1942. To produce plutonium in sizable quantities, the B Reactor would be 500 million times more powerful than the reactor built by Fermi.