Photo of D and DR Reactors from September 2021.
The world’s second full-scale nuclear reactor was D Reactor, built in the early 1940s. It went operational in December 1944. D Reactor ran through June 1967 and was ultimately cocooned (placed into a state of safe storage) in 2004.
D Reactor is unique in a couple of ways. First, the reactor’s control room is the property of the Smithsonian Institution in Washington, D.C., and has occasionally been part of an exhibit and placed on display at the museum. Second, the D Reactor’s early days of operation weren’t as smooth as operators would have liked.
D Reactor had only been operational for a few years when scientists detected a problem. They were so concerned D reactor would fail that they built another reactor, called the DR Reactor (DR stands for D-Replacement), right next door. DR Reactor went online in October 1950 as the fifth plutonium production reactor at the Hanford Site.
At about the same time, the problems associated with the D Reactor were solved and both D and DR Reactors ran side-by-side into the mid-1960s. In 2002 DR Reactor was also cocooned. D Reactor was one of the Site’s longest-serving facilities, with 22 years of service, while DR was online for the shortest amount of time: only 14 years.