It opened in 1958 and was used for nuclear reactorresearch and development into the 1990s. The last reactor was shut down in 1995, although decommissioning of the site will not finish till 2021. Winfrith housed nine reactors including the experimental Dragon reactor and a large Steam Generating Heavy Water Reactor (SGHWR) feeding the National Grid from 1968 to 1990. It also housed a used nuclear fuel examination facility, with the associated hot cells.
The Winfrith site was home to a number of experimental reactors including Zenith; Zebra; Juno; Nestor; Dimple; Zeus, and also impact test facilities.