WAGR generated 33MW of energy from enriched uranium rods inserted into 247 fuel channels running vertically through its graphite core. Fuel was installed in the core via corresponding channels in a concrete neutron shield and steel hot gas manifold above. Core, shield and hot box are supported by a 1.5m tall steel diagrid, sitting above a conical steel tundish intended to catch any debris from the core. The whole assembly is contained within an insulated steel pressure vessel, in turn encapsulated by a 1.5m thick reinforced concrete biological shield.
WAGR's structural frame, supporting reactor core, refuelling machine, heat exchangers and its outer protective sphere, is built of reinforced concrete.
Fuel was removed from the structure in 1983 and in 1989 the refuelling machine was dismantled. The top of the biological shield and top dome of the pressure vessel were removed between 1990 and 1992, and a new, heavy duty concrete shield installed to contain radioactivity within the core structure.
Where the refuelling machine had been housed, above the reactor core, a reinforced concrete floor was constructed to support a remote robotic arm and two cranes, installed in 1994. Modification of the reactor building's reinforced concrete structure was carried out to provide chambers where waste removed from the core could be packed, or 'sentenced', and assessed for radiological load before being committed for safe storage.
WAGR's four heat exchangers, weighing 190t each, were lifted out and transported as low level waste to the nearby nuclear storage facility at Drigg in 1995.