It was built at the Australian Atomic Energy Commission (AAEC) research establishment at Lucas Heights, Sydney, New South Wales.

Based on the DIDO reactor at Harwell in the UK, HIFAR was cooled and moderated by heavy water (D2O), and the fuel was enriched uranium.

Like DIDO, its original purpose was nuclear materials testing, using its high neutron flux to give materials intended for use in nuclear power reactors their entire expected lifetime neutron exposure in a relatively short period.

HIFAR went critical at 11:15 pm local time on 26 January 1958,[2] and was first run at full power of 10 MW (thermal) in 1960.

[6] OPAL is served by the same complex of research, isotope production and remote handling laboratories.