The B Reactor at the Hanford Site, near Richland, Washington, USA, was the first large-scale nuclear reactor ever built. The project was commissioned to produce plutonium-239 by neutron activation as part of the Manhattan Project, the United States nuclear weapons development program during World War II. The B reactor was fueled with metallic natural uranium, graphite moderated, and water-cooled. It has been designated a U.S. National Historic Landmark since August 19, 2008 and in July 2011 the National Park Service recommended that the B Reactor be included in a national historic park commemorating the Manhattan Project.
Read more about B Reactor: Reactor Design and Construction, Reactor Operation, Current Status, Timeline of Major Events, Sources