Highly toxic particles of uranium and plutonium persist in the soil at the site of British atomic bomb tests at Maralinga, in South Australia’s north, a study has found.
The nine nuclear tests between 1953 and 1963 dispersed more than 100 kilograms of tiny “hot” radioactive particles.
Scientists say they now have new evidence to show these radioactive particles remain, 60 years after the detonations.
Published on Friday in Nature’s Scientific Reports, and led by Monash University, the study also warns the particles are much more complex and varied than previously thought.
It provides the first mechanism for future modelling to predict the environmental life cycle of the plutonium, including how the particles are slowly broken down in the environment and potentially exposed to animals and humans through inhalation, the soil or ground water.
The Monash team used synchrotron radiation to decipher the physical and chemical make-up of the particles.
“It’s a major breakthrough,” said co-author Associate Professor Vanessa Wong.
“Our observations of the hot particles from the Maralinga provide a clear explanation for the complex and variable behaviour with respect to the chemical and physical weathering that has hindered predictive modelling to this day,” she said.
“This study provides a mechanistic foundation for predicting the future evolution of hot particles from high-temperature nuclear events and the likely exposure pathways.”
The researchers demonstrated that the complexity of the hot particles arose from their cooling from thousands of degrees Celsius in the explosion cloud.
Co-author Professor Joel Brugger said understanding the fate of hot particles in the arid environment of the Australian outback was critical to securing Australia in case of nuclear incidents in the region.
He said it was also vital to returning all the native land affected by the British tests to the traditional Anangu owners of the Maralinga Tjarutja lands.