National nuclear agency ANSTO, police and security authorities have completed an operation to repatriate two tonnes of radioactive waste sent to the UK for reprocessing in the 1990s.
The four 500-kilogram canisters of vitrified material safely arrived in Sydney overnight, authorities said on Sunday.
It's the second time radioactive waste has been repatriated to Australia, the first being in 2015 and the next not anticipated until the mid-2030s.
About 85 per cent of waste generated at ANSTO is directly associated with production of nuclear medicine including that used in the diagnosis of heart and lung conditions and treatment of some cancers.
Australia's reactor at Lucas Heights operates based on an array of nuclear fuel rods which only last a few months before being sent into storage to cool down.
The rods are then bunched and shipped to the UK, France or US for reprocessing, which involves removing and recycling uranium into power programs and solidifying the remaining waste.
Vitrification involves breaking up the material, mixing it in molten glass and solidifying it in steel canisters.
The four canisters just returned inside a 100-tonne storage cask with 20cm thick steel walls were initially sent to the UK in 1996.
"For decades Australians have benefited from medical, environmental, industrial and minerals research at Lucas Heights," ANSTO group executive Pamela Naidoo-Ameglio said.
"Those benefits include production of millions of doses of nuclear medicine, increased profitability of our mining industry, irradiation of silicon used in everything from fast trains to hybrid cars, and a base of knowledge that secures Australia's position in international nuclear non-proliferation talks."
Ms Naidoo-Ameglio said there were comprehensive plans to safely manage the waste.
ANSTO general manager of waste management Paula Berghofer said similar storage casks had been successfully used in 180 nuclear shipments around the world over more than 40 years.
Twelve have landed in Australia in total since 1963.
