A radiation safety expert has described the loss of a tiny radioactive capsule along a 1,400-kilometre stretch of road in Western Australia as a 'bizarre, one-in-100-year event'.
Health authorities issued an urgent warning on Friday after the 8-millimetre capsule — which has the potential to cause severe burns — was lost somewhere between a mine site in Newman, in WA's north, and Perth.
The caesium-137 capsule was part of a radiation gauge commonly used in the mining industry.
The gauge was packaged, then transported from the Rio Tinto mine site on January 11 and arrived in a depot in the Perth suburb of Malaga on January 16.
However, it wasn't until January 25 that authorities were notified that the radioactive capsule was missing, after it was unpacked for inspection.
Authorities believe it fell through a hole where a bolt had been dislodged after a container collapsed inside the truck.
Radiation Services WA general manager Lauren Steen said it was a “highly unlikely” scenario, due to the safety measures typically in place for the transit of radioactive materials.
“[It's] highly unusual. It’s left my head in a bit of a spin,” she said.
“Typically they’re transported in highly protected casing that are subject to a certification verification stage. The housing is subjected to rigorous testing for vibrations, heat, high impact.
“If the source is certified and the packaging and the transport requirements … basically make it a very unlikely occurrence.”
Capsule poses health hazard
The radioactive capsule formed part of a gauge which is commonly used to detect radiation levels in oil, gas and other processing plants.
“If you were to stand 1 metre [away] … you would be receiving about the equivalent of 17 chest x-rays,” Ms Steen said.
“If you were to hold the source in your hand for a substantial period of time, you would start to notice some radiation burns.”
Western Australia's Chief Health Officer, Andy Robertson, has warned the community not to handle the device if they come across it, due to the dangerous radiation it emits.
“We strongly discourage people from picking it up. Certainly don't put it in a pocket. Don't put it in your car. Don't put it on your sideboard, because it will continue to radiate,” he said.
“While you may not have immediate health effects, they can occur relatively rapidly over a short period of time, if it is kept close to the body.
“If it's less than 1 metre, then people could end up developing redness of the skin and eventually burns of the skin.
"If it was kept long enough … They could also have some more acute effects, including impacts on their their immune system and their gastrointestinal system.”
The Department of Fire and Emergency Services (DFES) Acting Superintendent and Incident Controller Darryl Ray said crews were searching for the missing device using specialist equipment.
“What we're not doing is trying to find a tiny little device by eyesight,” he said.
“We're using the radiation detectors to locate the gamma rays using the meters that will help us then locate the small device.”
Safety highest priority, Rio Tinto says
In a statement, Rio Tinto said the capsule was being transported by a contractor.
“An expert radioactive materials handler was engaged by Rio Tinto to handle and package the capsule and transport it safely off site,” the company said.
“Safety is our highest priority, and we are working with and supporting the Radiological Council, the contractors involved, as well as emergency services to assist in the search.”
DFES is leading a multi-agency search mission, which includes West Australian police and the Department of Health.
Authorities have flagged that it could take weeks to finish covering the potential search area and there was no certainty the capsule would be found.
