The white ocean sands of Western Australia’s Montebello Islands may appear inviting, but 70 years ago they were the site of Britain’s first nuclear tests.
Now researchers are working to uncover how much and what type of radioactive material persists in sediment on the ocean floor of the archipelago, made up of 265 low-lying islands and islets, 1,200km north of Perth. They hope to get a clearer idea of its effects on the area’s abundant marine life and any lingering dangers to people who visit the islands for tourism or fishing.
The nuclear fallout from atomic blasts in the 1950s have been well studied on land, but little is known about how radioactive sands affect the 60,000-hectare marine park’s ecosystem.
In June 2020 a team led by Madison Hoffman, an environmental radioecologist at Edith Cowan University, collected hundreds of kilograms of sediment from an area near the blast sites, 120km west of Dampier, for analysis.
Hoffman says they detected levels of radioactivity higher than background levels, as expected.
“Those levels are highest in areas around where those three detonations took place, but we also have some areas which have come up with levels a little higher than we expected for where we found them.”
The 12 nuclear tests carried out between 1952 and 1957 – including three in the Montebellos – were part of a secretive deal between Britain and Australia that was championed by the then prime minister, Robert Menzies. Further “minor trials” were carried out in South Australia until 1963.
The first test, codenamed Operation Hurricane, took place on 4 October 1952 at a lagoon off Trimouille Island in the Montebellos.
A decommissioned warship, HMS Plym, was rigged up with a 7kg plutonium device, sending tonnes of seawater and mud 3,000 metres into the air and impregnating the ocean sand with radioactive isotopes.
On 16 May and 19 June 1956 two more bombs were set off from towers at Trimouille and Alpha islands as part of Operation Mosaic. The bombs were boosted with hydrogen and lithium and were the biggest ever detonated in Australia.
Hoffman says while some radionuclides, or radioactive atoms, are blasted inside sand grains, others attach to the surface of sediment and shift in rough weather, such as during cyclonic activity.
“When we know what radionuclides there are and what ratios they are in, they can act like a fingerprint, kind of like a forensics tool that is distinct to the Montebellos,” Hoffman says.
“When sediment rock gets moved from point A to point B, it is taking those radionuclides with it and potentially moving those hotspots and migrating them around.”
Hoffman wants to know where these hotspots are so she can study how the radiation exposure affects sediment-dwelling marine life. The area is home to a rich variety of marine species including dugongs, turtles, whales, hundreds of fish species and mangroves.
The Australian Radiation Protection and Nuclear Safety Agency has classified the area as an “existing exposure situation” with radiation levels “not considered to be excessively dangerous”.
It says environmental assessments show “no significant risk to the local marine ecosystem and that remediation attempts are not justified and could devastate local ecosystems”.
“There are no changes to existing arrangements for tourists.”
But Darren Koppel, a marine contaminant expert with the Australian Institute of Marine Science, says low levels of radiation over long periods can cause chronic toxicity to plants and other organisms.
“We do not have much data on the chronic effects of radiation to marine organisms, so this type of research is critical to fill those data gaps,” Koppel says.
“The most likely effect is that sensitive organisms and plants will have stopped living or growing in the areas with higher radioactivity, leaving only the more tolerant species.”
The Montebello Islands are managed by the WA Department of Biodiversity, Conservation and Attractions.
It says there are still “slightly elevated radiation levels” at Trimouille and Alpha islands and warns tourists not to camp or spend longer than one hour at those sites.
Tourists travel from the nearby towns of Karratha, Port Hedland, Onslow and Dampier on fishing trips. Despite warning signs , the department has found evidence of campers on the islands in recent years.
In the Great Victoria Desert, in outback South Australia, authorities spent millions trying to clean up radioactive fallout from nuclear testing at Maralinga, where the British detonated seven atomic bombs.
According to researchers at Monash University, residual plutonium and uranium still contaminate the land at Maralinga as tiny radioactive grains in the soil.
Little heed was given to the Anangu Pitjantjatjara people who lived on the land, who lived with the legacy of the explosions for decades afterwards. It wasn’t until 1994 that the Australian government paid $13.5m in compensation for what had been done to the land.
British and Australian servicemen exposed to radiation by the blasts have also fought long campaigns for the effects on their health to be recognised and adequately compensated.
Last month, the outgoing British prime minister, Boris Johnson, announced that £500,000 ($870,000) would be spent to commemorate the servicemen who worked for Britain’s nuclear testing program.
On 5 September he said in a letter to veterans of the nuclear tests they deserved medals for “having forged and protected our country’s protective shield”.
Dear veterans, it is my firm belief that you deserve medallic recognition.
— Boris Johnson (@BorisJohnson) September 5, 2022
Thanks to your efforts all those years ago, more than 67 million people in the UK and across NATO live in safety that you helped to provide.
I would like to offer my profound thanks for your sacrifice. pic.twitter.com/Fc7yvrmaSJ
Hoffman says that key technical documents about the nuclear testing, which could help with her research, were reclassified by the UK in 2018.
“We have so little documentation or information about what really happened,” Hoffman said.
“Without that information and all the really crucial statistics [about the blasts] it is really difficult to make sense of the answers we have now in relation to what originally happened.”
