Hanford D and DR Reactors

The world’s second full-scale nuclear reactor was the D Reactor at Hanford which was built in the early 1940’s and went operational in December of 1944. D Reactor ran through June of 1967, and was ultimately cocooned in 2004.

The reactor next to it is known as DR, or the D Replacement. DR Reactor was built in 1949-50 because Hanford scientists thought D Reactor was going to fail and they wanted to take advantage of the D Reactor pumphouse and other support buildings. However, they solved D Reactor's problems and the two reactors operated side-by-side until the mid-1960s. The Control Room of D Reactor is housed in the Smithsonian Museum, but is currently not on display.