At 11:15 pm on Sunday 26 January 1958, Australia Day, the High Flux Australian Reactor went critical for the first time with 11 of 25 fuel elements loaded. The men in the control room had come from Oak Ridge, Chalk River and Harwell. HIFAR was Australia's first nuclear reactor.
HIFAR was one of six DIDO-class reactors built worldwide, a heavy-water-moderated 10 MW design. The reactor block was a right irregular decagonal prism of iron-shot concrete, steel-clad, 6.7 metres across the flats, sitting behind the white containment dome that became the visible landmark of the Lucas Heights skyline. Head Wrightson of Stockton-on-Tees built it under contract from 1955, with Stephenson and Turner of Sydney as consulting architects.
HIFAR was built to support a civil nuclear power programme that Australia never adopted. What kept it running for half a century instead was nuclear medicine and semiconductor production. The reactor produced technetium-99m generators shipped to 11 Asia-Pacific countries, and from around 1985 it irradiated high-purity silicon for the global semiconductor industry.
HIFAR shut down at 10:25 am on 30 January 2007, 49 years and 4 days after first criticality, the last of the six DIDO-class reactors worldwide to go cold. OPAL, a 20 MW open-pool reactor built by INVAP in Argentina, had reached full power on the same site three months earlier. Engineering Heritage Australia listed HIFAR as a National Engineering Landmark in 2001, and the containment shell is retained while Phase A decommissioning proceeds.