(CNN) — It’s like looking for a needle in a haystack: an 8mm by 6mm silver capsule, no bigger than a quarter, believed to be lost somewhere along the state’s vast desert highway. Australia’s largest.
Mining company Rio Tinto apologized on Monday, saying it was supporting the state government’s efforts to find a capsule containing cesium-137, a highly radioactive substance used in mining equipment.
Western Australian state authorities are searching for a small radioactive capsule believed to have fallen from the truck. (Department of Fire and Emergency Services/AP)
Rio Tinto said it had checked all roads in and out of the Kutai-Dari mine site in Western Australia’s far north, where the rig was located, before a contractor collected it for travel to South Australia’s capital, Perth.
Officials believe the capsule, which emits gamma and beta rays, fell from the back of a truck traveling along an 870-mile (1,400-kilometer) stretch of the Great Northern Highway, farther than the California coast.
Officials warn that the capsule’s small size and great distance make it less likely to be found.
And it is already feared to be moving further from the search area, creating a radioactive health hazard for anyone who comes across the device for the next 300 years.
How did it disappear?
State officials raised the alarm on Friday, warning residents of a radioactive leak in the southern part of the state, including the northeastern suburbs of Perth, the state capital of about 2 million people.
A chart provided by the Western Australian Department of Health shows the size of a capsule compared to a coin. (Western Australia Department of Health)
According to officials, the capsule was placed in a package on January 10 and picked up by a contractor at Rio Tinto’s Gutai-Dari mine on January 12.
The vehicle was on the road for four days, arriving in Perth on January 16, but was only unloaded for inspection on January 25, when it was found missing.
“On opening the package, it was discovered that the meter was broken and one of the four mounting bolts was missing, and evidence and all meter screws were missing,” the Department of Fire and Emergency Services (DFES) said.
They believe strong vibrations caused by bumpy roads damaged the pack.
How dangerous is it?
Experts warn that contact with cesium-137 can create serious health problems for humans: close exposure, radiation sickness and serious cancer risks, especially for people unknowingly exposed for long periods of time.
Radiation Services WA, a radiation safety consultancy, says that staying within one meter of the capsule for one hour can produce up to 17 standard chest X-rays of around 1.6 millisieverts (mSv).
Ingesting the capsule can cause “severe damage” to the fingers and surrounding tissue, the company said in a statement.
Evan Kempson, associate professor of biophysics at the University of South Australia, said the worst-case scenario would be for a child to pick up a capsule of interest and put it in their pocket.
“It’s rare, but it can happen and has happened before,” Kempson said. “There are some previous examples of people finding similar things and getting radiation poisoning, but they were much stronger than the current missing capsule.”
“We are all exposed to a constant level of radiation from the things around us and the food we eat, but the main concern now is the health impact of the person who finds the capsule.”
State officials are searching for the capsule along a stretch of the Great Northern Highway in Western Australia. (Department of Fire and Emergency Services/AP)
How rare is it to lose a radiation device?
The incident surprised experts who said handling of radioactive materials like cesium-137 is highly regulated with strict protocols for its transport, storage and disposal.
Rio Tinto said it continues to transport and store hazardous materials as part of its business and hires specialist contractors to handle radioactive materials. The small capsule is part of a density meter used to measure the density of iron ore feed at the Kudai-Dari mine, it said in a statement.
Radiation Services WA It says that radioactive materials are transported through Western Australia daily without any problems. “In this case, there appears to be a failure of control measures that are routinely implemented,” he said, adding that he had nothing to do with the loss of the capsule.
Pradeep Deb, a professor and radiation safety officer at RMIT University in Melbourne, said the loss of the capsule was “extremely unusual” according to Australian safety regulations.
The name of the logistics company used to transport the device was not disclosed, Rio Tinto said.
What happens in search?
Authorities are trying to locate the device, which has special radiation detectors installed to look for vehicles slowing down to 50 kilometers per hour (31 miles per hour) in both directions on the highway.
“It will take approximately five days to travel the original route,” DFES said in a statement on Monday.
Dale Bailey, a professor of medical imaging sciences at the University of Sydney, said the slow speed was necessary to give the team time to detect the radiation.
“Radiation detectors in moving vehicles can be used to detect radiation above natural levels, but at low levels of radiation at the source, they must ‘sweep’ the area relatively slowly,” he said.
Officials warned the public not to come within five meters of the device, although they admitted it was difficult to see from a distance.
“What we don’t do is try to detect a small device with the naked eye. We use radiation detectors to detect gamma rays,” DFES officials said.
But there are fears that it is no longer within the search zone: The capsule could have lodged in another vehicle’s tire and been carried a long distance or even scattered by wild animals, including birds, officials say.
“Imagine if it’s a bird of prey, for example, that picks up the capsule and carries it out of the (original) search area, there’s a lot of uncertainty and that’s going to cause more problems,” said Dave Sweeney, a nuclear policy major. Journalist and advocate for media at the Australian Conservation Foundation.
“Obviously this evidence needs to be recovered and preserved, but there are so many variables and we don’t know what will happen.”
A conveyor belt transports iron ore at the Kutai-Dari mine operated by Rio Tinto in the Pilbara region of Western Australia on June 21, 2022. (Carla Gottgens/Bloomberg/Getty Images)
What if it is not available?
Cesium-137 has a half-life of about 30 years, meaning that the radioactivity in the capsule will halve after three decades and halve again after 60 years.
At that rate, the capsule would remain radioactive for the next 300 years, RMIT University’s Deb said.
“Cesium-137 is usually a sealed source, meaning that if it doesn’t break up, it won’t contaminate the soil or the environment. If the capsule isn’t found, it won’t contaminate or change radioactivity in the surrounding soil,” he added.
Kempson of the University of South Australia said if it was lost in an isolated area, “it’s unlikely to have much of an impact”.
Rio Tinto, one of the world’s largest mining companies, operates 17 iron ore mines in the Pilbara region of Western Australia. The company’s mining operations have caused controversy in the past, with the destruction of two ancient rock shelters in the Jugan Valley in 2020 leading to an apology and the resignation of then-CEO Jean-Sébastien Jacqueline.
With earlier reporting by CNN’s Amarachi Ori
