Omega West Reactor

OWR was completed in 1956 and primarily used for scientific scale nuclear research until it was fully decommissioned in 1994.

The reactor's low-pressure design and tall vertical vessel made it possible for a lead glass window to be installed at the top, through which the active core could be viewed directly.

The core was surrounded by a heavy concrete shield which also served as a secondary containment vessel.

A typical core loading consisted of 33 fuel elements, each containing 236 grams of 93% enriched Uranium (when new).

[2] The reactor operated successfully until 1992 when an unplanned power spike caused an automatic shutdown.