Radiation at Montebello Islands still 4,500 times higher than WA coast after nuclear blasts

Australia Broadcast Center

5 days ago

Cam McGurk's stories of one of Australia's most heavily irradiated areas come drenched in warm Pilbara sunshine.
"I actually spent my honeymoon at the Montebello Islands," Mr McGurk, a longtime member of the Ashburton Anglers fishing club, said.
"It was the middle of COVID, so all the travel restrictions were in place … that was the one island holiday where I could take my beautiful wife.
The fondness locals like Mr McGurk feel for the islands, about 1,300 kilometres north of Perth, could soon be given fresh pause.
According to a landmark study published today, the archipelago's atomic contamination runs astonishingly deep.
The Montebello Islands were the site of three British atmospheric nuclear weapons tests between 1952 and 1956.
Two of the around 174 spits of sandy earth are still subject to hour-long visitation limits.
Since 2019, a team of researchers from Edith Cowan University has sought to measure precisely how much plutonium remains in the islands' marine sediment.
Their findings have now revealed levels reaching up to 4,500 times higher than the rest of the WA coast.
Scientists spent eight days on the Montebello Islands, diving to gather surface sediment from the ocean floor.
Samples were sent to the Australian Radiation Protection and Nuclear Safety Agency, the chief regulator for historic nuclear testing sites.
"We're able to essentially create a map with the over 66 locations that we took samples of sediment from," lead researcher and PhD candidate Madison Williams-Hoffman said.
Ms Williams-Hoffman said two "mechanisms" were spreading radiation through the islands over the past 70 years.
"The first one is the plume trajectories … like the mushroom clouds that you conjure in your mind when you think of nuclear detonations," she said.
"Those travelled with the wind direction at the time of the detonations."
Second, decades of tides and severe weather dispersed residual plutonium in unexpected ways.
"There are two cyclones a year that directly impact that part of WA, and so sediment is being tossed up and around, and things [are] moving," Ms Williams-Hoffman said.
She said concentrations in the islands' north were "comparable" to other places touched by nuclear testing, including French Polynesia and the Marshall Islands.
Any degree of similarity was remarkable because the Marshall Islands suffered a cumulative nuclear impact 700 times greater than the Montebello Islands.
"It makes us question what's different between the two sites," Ms Williams-Hoffman said.
The legacy of British nuclear testing in Australia is fraught with displacement and disease.
Following three major tests conducted on the Montebello Islands, two more nuclear devices were detonated at Emu Fields and another seven at Maralinga in South Australia.
Ray Kaye, former president of the Australian Ex-Services Atomic Survivors Association, said it was crucial the impacts of radiation were recorded.
The 85-year-old, who later contracted leukaemia, was awarded a medal by the British government for his involvement in the SA nuclear tests.
Mr Kaye reminisced on a 2016 trip with his fellow veterans to the Montebello Islands, marking the 60th anniversary of the blasts.
WA Parks and Wildlife marine program coordinator Tim Hunt said managing radiation on the Montebello Islands was an "interesting" part of the job.
"When I came into this role almost nine years ago, I never thought I'd have to get my physics hat on and learn about radiation," Mr Hunt said.
He noted that exposure to marine sediment was far less concerning to authorities.
"I'm not an expert, but people aren't going down and putting their head in the sand at 10 or 16 metres," he said.
"Our current understanding is that the measures we have in place are sufficient to mitigate that risk."
Visitors to Trimouille and Alpha Islands, where the three tests took place, are advised to restrict their time to no more than one hour per day, and not to disturb the soil or handle any relics.
Ms Williams-Hoffman said the results were an important step in understanding the repercussions of radionuclides in Australia.
Next, researchers will evaluate the effects of such high radiation on the environment.
"It's kind of like walking before you can run," she said.
"Now that we have these numbers or values in hand, then we can later do those assessments in terms of … how much radiation a person, or perhaps most important with sediment considering it's under water … the animals, the fish, and the plants are exposed to."
For Cam McGurk, his appreciation for the "boating and fishermen's playground" reels back to 1998, when a special permit was needed to travel there.
He mused that the legend of atomic testing had likely shielded the islands from over-tourism, but supported further monitoring.