A new study has highlighted the first international standards needed to safeguard against contamination from nuclear testing, and a Kokatha Elder says the impact of nuclear testing at Maralinga cannot be forgotten.
More than 100 kilograms of highly toxic uranium and plutonium was dispersed in the form of tiny 'hot' radioactive particles after nuclear tests were conducted by the British in remote areas of South Australia, including Maralinga.
Scientists have new evidence these radioactive particles persist in soils to this day, more than 60 years after the detonations.
The British detonated nine nuclear bombs and conducted nuclear tests in South Australia between 1953 and 1963.
There had previously been limited understanding in how plutonium was released from the particles into the environment for uptake by wildlife around Maralinga.
The new study, published in Nature's Scientific Reports, led by Monash University researchers, warns the hot particles are more complex and varied than previously thought.
Currently, there are no international best practice standards for the environmental impact or risk assessment of plutonium and uranium-rich hot particles released during nuclear testing.
This study provides the first mechanism for future modelling to predict the environmental life cycle of plutonium from hot particles, including how they are slowly broken down in the environment over a long period, and potentially exposed to animals and humans through inhalation, soil or ground water.
"The resulting radioactive contamination and cover-up continues to haunt us," lead study author from Monash University's School of Earth, Atmosphere and Environment Dr Megan Cook said.
"The results of our study profoundly changes our understanding of the nature of hot particles at Maralinga - despite the fact that those were some of the best studied particles anywhere in the world."
Sue Haseldine, who grew up in the Koonibba district in the 1950s and 1960s, has long campaigned against nuclear testing and weapons.
She has been part of the International Campaign to Abolish Nuclear Weapons (ICAN), an organisation awarded the Nobel Peace Prize in 2017, and has spoken about her experience growing up in the shadow of nuclear testing at Maralinga.
Ms Haseldine said the people in the area had long-suspected there were health issues deriving from those tests.
"Experts would tell you that radiation will not last for 60 years, nor 60,000, but for a long, long time, and it is still causing troubles today," she said.
"The old ladies told me these cancers and illnesses were not around before the bomb and over the years I have seen the rates go up.
"There are a lot more younger people with heart problems - it is known that radiation problems can cause heart diseases - and it is coming down through the generations."
Ms Haseldine said the testing and fallout from Maralinga was not spoken about enough and that was why her campaigning with ICAN was so important.
"It is important to let people know what the government's legacy is to us through their testing and we have to keep the past alive to protect the future, so they don't do it to future generations," she said.
"I grew up in the Koonibba district, but the radiation didn't just stay in the Maralinga area."
Study co-author professor Joël Brugger said the study invited a revisit of the implications of earlier results for the fate of plutonium at Maralinga.
"Understanding the fate of hot particles in the arid environment setting of the Australian outback is critical for securing Australia in case of nuclear incidents in the region, and returning all the native land affected by the British tests to the traditional Anangu owners of the Maralinga Tjarutja lands."
The research team used synchrotron radiation at the Diamond Light Source near Oxford in the United Kingdom to decipher the physical and chemical make-up of the particles.
At Monash, they dissected some of the hot particles using a nano-sized ion beam, and further characterised the complex make-up of these particles down to the nano-size.
"It's a major breakthrough," study co-author associate professor Vanessa Wong said.
"Our observations of the hot particles from Maralinga provide a clear explanation for the complex and variable behaviour of different hot particles with respect to the chemical and physical weathering that has hindered predictive modelling to this day.
"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 the complexity of the hot particles arose from the cooling of polymetallic melts from thousands of degrees Celsius in the explosion cloud during their formation.
"We found that the particles contained low-valence plutonium-uranium-carbon compounds that are typically highly reactive - which is unexpected for particles that survived for over 30 years in the environment," corresponding author Dr Barbara Etschmann said.
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