We sliced open radioactive particles from soil in South Australia and found they may be leaking plutonium


National Archives of Australia

Barbara Etschmann, Monash University; Joel Brugger, Monash University, and Vanessa Wong, Monash UniversityAlmost 60 years after British nuclear tests ended, radioactive particles containing plutonium and uranium still contaminate the landscape around Maralinga in outback South Australia.

These “hot particles” are not as stable as we once assumed. Our research shows they are likely releasing tiny chunks of plutonium and uranium which can be easily transported in dust and water, inhaled by humans and wildlife and taken up by plants.

A British nuclear playground

After the US atomic bombings of Hiroshima and Nagasaki in 1945, other nations raced to build their own nuclear weapons. Britain was looking for locations to conduct its tests. When it approached the Australian government in the early 1950s, Australia was only too eager to agree.

Between 1952 and 1963, Britain detonated 12 nuclear bombs in Australia. There were three in the Montebello Islands off Western Australia, but most were in outback South Australia: two at Emu Field and seven at Maralinga.

British nuclear tests left behind a radioactive legacy.
National Archives of Australia

Besides the full-scale nuclear detonations, there were hundreds of “subcritical” trials designed to test the performance and safety of nuclear weapons and their components. These trials usually involved blowing up nuclear devices with conventional explosives, or setting them on fire.

The subcritical tests released radioactive materials. The Vixen B trials alone (at the Taranaki test site at Maralinga) spread 22.2 kilograms of plutonium and more than 40 kilograms of uranium across the arid landscape. For comparison, the nuclear bomb dropped on Nagasaki contained 6.4 kilograms of plutonium, while the one dropped on Hiroshima held 64 kilograms of uranium.

These tests resulted in long-lasting radioactive contamination of the environment. The full extent of the contamination was only realised in 1984, before the land was returned to its traditional owners, the Maralinga Tjarutja people.

Hot potatoes

Despite numerous cleanup efforts, residual plutonium and uranium remains at Maralinga. Most is present in the form of “hot particles”. These are tiny radioactive grains (much smaller than a millimetre) dispersed in the soil.

Plutonium is a radioactive element mostly made by humans, and the weapons-grade plutonium used in the British nuclear tests has a half life of 24,100 years. This means even 24,100 years after the Vixen B trials that ended in 1963, there will still be almost two Nagasaki bombs worth of plutonium spread around the Taranaki test site.

Plutonium emits alpha radiation that can damage DNA if it enters a body through eating, drinking or breathing.




Read more:
Dig for secrets: the lesson of Maralinga’s Vixen B


In their original state, the plutonium and uranium particles are rather inactive. However, over time, when exposed to atmosphere, water, or microbes, they may weather and release plutonium and uranium in dust or rainstorms.

Until recently, we knew little about the internal makeup of these hot particles. This makes it very hard to accurately assess the environmental and health risks they pose.

Monash PhD student Megan Cook (the lead author on our new paper) took on this challenge. Her research aimed to identify how plutonium was deposited as it was carried by atmospheric currents following the nuclear tests (some of it travelled as far as Queensland!), the characteristics of the plutonium hot particles when they landed, and potential movement within the soil.

Nanotechnology to the rescue

Previous studies used the super intense X-rays generated by synchrotron light sources to map the distribution and oxidation state of plutonium inside the hot particles at the micrometre scale.

To get more detail, we used X-rays from the Diamond synchrotron near Oxford in the UK, a huge machine more than half a kilometre in circumference that produces light ten billion times brighter than the Sun in a particle accelerator.

Studying how the particles absorbed X-rays revealed they contained plutonium and uranium in several different states of oxidation – which affects how reactive and toxic they are. However, when we looked at the shadows the particles cast in X-ray light (or “X-ray diffraction”), we couldn’t interpret the results without knowing more about the different chemicals inside the particles.

To find out more, we used a machine at Monash University that can slice open tiny samples with a nanometre-wide beam of high-energy ions, then analyse the elements inside and make images of the interior. This is a bit like using a lightsaber to cut a rock, only at the tiniest of scales. This revealed in exquisite detail the complex array of materials and textures inside the particles.

Plutonium and uranium show up as bright lumps embedded in darker iron-aluminium alloy in this electron microscope image.
Cook et al (2021), Scientific Reports, Author provided

Much of the plutonium and uranium is distributed in tiny particles sized between a few micrometres and a few nanometres, or dissolved in iron-aluminium alloys. We also discovered a plutonium-uranium-carbon compound that would be destroyed quickly in the presence of air, but which was held stable by the metallic alloy.

This complex physical and chemical structure of the particles suggests the particles formed by the cooling of droplets of molten metal from the explosion cloud.

In the end, it took a multidisciplinary team across three continents — including soil scientists, mineralogists, physicists, mineral engineers, synchrotron scientists, microscopists, and radiochemists — to reveal the nature of the Maralinga hot particles.

From fire to dust

Our results suggest natural chemical and physical processes in the outback environment may cause the slow release of plutonium from the hot particles over the long term. This release of plutonium is likely to be contributing to ongoing uptake of plutonium by wildlife at Maralinga.

Even under the semi-arid conditions of Maralinga, the hot particles slowly break down, liberating their deadly cargo. The lessons from the Maralinga particles are not limited to outback Australia. They are also useful in understanding particles generated from dirty bombs or released during subcritical nuclear incidents.




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There have been a few documented instances of such incidents. These include the B-52 accidents that resulted in the conventional detonation of thermonuclear weapons near Palomares in Spain in 1966, and Thule in Greenland in 1968, and the explosion of an armed nuclear missile and subsequent fire at the McGuire Air Force Base in the USA in 1960.

Thousands of active nuclear weapons are still held by nations around the world today. The Maralinga legacy shows the world can ill afford incidents involving nuclear particles.The Conversation

Barbara Etschmann, Research officer, Monash University; Joel Brugger, Professor of Synchrotron Geosciences, Monash University, and Vanessa Wong, Associate Professor, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Japan plans to dump a million tonnes of radioactive water into the Pacific. But Australia has nuclear waste problems, too


Tilman Ruff, University of Melbourne and Margaret Beavis

The Japanese government recently announced plans to release into the sea more than 1 million tonnes of radioactive water from the severely damaged Fukushima Daiichi nuclear plant.

The move has sparked global outrage, including from UN Special Rapporteur Baskut Tuncak who recently wrote,

I urge the Japanese government to think twice about its legacy: as a true champion of human rights and the environment, or not.

Alongside our Nobel Peace Prize-winning work promoting nuclear disarmament, we have worked for decades to minimise the health harms of nuclear technology, including site visits to Fukushima since 2011. We’ve concluded Japan’s plan is unsafe, and not based on evidence.

Japan isn’t the only country with a nuclear waste problem. The Australian government wants to send nuclear waste to a site in regional South Australia — a risky plan that has been widely criticised.

Contaminated water in leaking tanks

In 2011, a massive earthquake and tsunami resulted in the meltdown of four large nuclear reactors, and extensive damage to the reactor containment structures and the buildings which house them.

Water must be poured on top of the damaged reactors to keep them cool, but in the process, it becomes highly contaminated. Every day, 170 tonnes of highly contaminated water are added to storage on site.

As of last month, this totalled 1.23 million tonnes. Currently, this water is stored in more than 1,000 tanks, many hastily and poorly constructed, with a history of leaks.

How does radiation harm marine life?

If radioactive material leaks into the sea, ocean currents can disperse it widely. The radioactivity from Fukushima has already caused widespread contamination of fish caught off the coast, and was even detected in tuna caught off California.




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Ionising radiation harms all organisms, causing genetic damage, developmental abnormalities, tumours and reduced fertility and fitness. For tens of kilometres along the coast from the damaged nuclear plant, the diversity and number of organisms have been depleted.

Of particular concern are long-lived radioisotopes (unstable chemical elements) and those which concentrate up the food chain, such as cesium-137 and strontium-90. This can lead to fish being thousands of times more radioactive than the water they swim in.

Failing attempts to de-contaminate the water

In recent years, a water purification system — known as advanced liquid processing — has been used to treat the contaminated water accumulating in Fukushima to try to reduce the 62 most important contaminating radioisotopes.

But it hasn’t been very effective. To date, 72% of the treated water exceeds the regulatory standards. Some treated water has been shown to be almost 20,000 times higher than what’s allowed.




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The cherry trees of Fukushima


One important radioisotope not removed in this process is tritium — a radioactive form of hydrogen with a half-life of 12.3 years. This means it takes 12.3 years for half of the radioisotope to decay.

Tritium is a carcinogenic byproduct of nuclear reactors and reprocessing plants, and is routinely released both into the water and air.

The Japanese government and the reactor operator plan to meet regulatory limits for tritium by diluting contaminated water. But this does not reduce the overall amount of radioactivity released into the environment.

How should the water be stored?

The Japanese Citizens Commission for Nuclear Energy is an independent organisation of engineers and researchers. It says once water is treated to reduce all significant isotopes other than tritium, it should be stored in 10,000-tonne tanks on land.

If the water was stored for 120 years, tritium levels would decay to less than 1,000th of the starting amount, and levels of other radioisotopes would also reduce. This is a relatively short and manageable period of time, in terms of nuclear waste.

Then, the water could be safely released into the ocean.

Nuclear waste storage in Australia

Australians currently face our own nuclear waste problems, stemming from our nuclear reactors and rapidly expanding nuclear medicine export business, which produces radioisotopes for medical diagnosis, some treatments, scientific and industrial purposes.




Read more:
Australia should explore nuclear waste before we try domestic nuclear power


This is what happens at our national nuclear facility at Lucas Heights in Sydney. The vast majority of Australia’s nuclear waste is stored on-site in a dedicated facility, managed by those with the best expertise, and monitored 24/7 by the Australian Federal Police.

But the Australian government plans to change this. It wants to transport and temporarily store nuclear waste at a facility at Kimba, in regional South Australia, for an indeterminate period. We believe the Kimba plan involves unnecessary multiple handling, and shifts the nuclear waste problem onto future generations.

The proposed storage facilities in Kimba are less safe than disposal, and this plan is well below world’s best practice.

The infrastructure, staff and expertise to manage and monitor radioactive materials in Lucas Heights were developed over decades, with all the resources and emergency services of Australia’s largest city. These capacities cannot be quickly or easily replicated in the remote rural location of Kimba. What’s more, transporting the waste raises the risk of theft and accident.

And in recent months, the CEO of regulator ARPANSA told a senate inquiry there is capacity to store nuclear waste at Lucas Heights for several more decades. This means there’s ample time to properly plan final disposal of the waste.

The legislation before the Senate will deny interested parties the right to judicial review. The plan also disregards unanimous opposition by Barngarla Traditional Owners.




Read more:
Uranium mines harm Indigenous people – so why have we approved a new one?


The Conversation contacted Resources Minister Keith Pitt who insisted the Kimba site will consolidate waste from more than 100 places into a “safe, purpose-built, state-of-the-art facility”. He said a separate, permanent disposal facility will be established for intermediate level waste in a few decades’ time.

Pitt said the government continues to seek involvement of Traditional Owners. He also said the Kimba community voted in favour of the plan. However, the voting process was criticised on a number of grounds, including that it excluded landowners living relatively close to the site, and entirely excluded Barngarla people.

Kicking the can down the road

Both Australia and Japan should look to nations such as Finland, which deals with nuclear waste more responsibly and has studied potential sites for decades. It plans to spend 3.5 billion euros (A$5.8 billion) on a deep geological disposal site.




Read more:
Risks, ethics and consent: Australia shouldn’t become the world’s nuclear wasteland


Intermediate level nuclear waste like that planned to be moved to Kimba contains extremely hazardous materials that must be strictly isolated from people and the environment for at least 10,000 years.

We should take the time needed for an open, inclusive and evidence-based planning process, rather than a quick fix that avoidably contaminates our shared environment and creates more problems than it solves.

It only kicks the can down the road for future generations, and does not constitute responsible radioactive waste management.


The following are additional comments provided by Resources Minister Keith Pitt in response to issues raised in this article (comments added after publication):

(The Kimba plan) will consolidate waste into a single, safe, purpose-built, state-of-the-art facility. It is international best practice and good common sense to do this.

Key indicators which showed the broad community support in Kimba included 62 per cent support in the local community ballot, and 100 per cent support from direct neighbours to the proposed site.

In assessing community support, the government also considered submissions received from across the country and the results of Barngarla Determination Aboriginal Corporation’s own vote.

The vast majority of Australia’s radioactive waste stream is associated with nuclear medicine production that, on average, two in three Australians will benefit from during their lifetime.

The facility will create a new, safe industry for the Kimba community, including 45 jobs in security, operations, administration and environmental monitoring.The Conversation

Tilman Ruff, Associate Professor, Education and Learning Unit, Nossal Institute for Global Health, School of Population and Global Health, University of Melbourne and Margaret Beavis, Tutor Principles of Clinical Practice Melbourne Medical School

This article is republished from The Conversation under a Creative Commons license. Read the original article.