A tiny, potentially deadly, radioactive capsule that has been missing for more than two weeks somewhere in the vastness of Western Australia might never be found, authorities have conceded.
On Sunday, Western Australia’s Department of Fire and Emergency Services (Dfes) revealed it was bringing in new radiation detection equipment that could be fitted to vehicles – superseding handheld sensors – to help locate the capsule somewhere along the 1,400km journey from which it originally disappeared.
The 8mm by 6mm capsule – a 19-gigabecquerel caesium 137 ceramic source, commonly used in radiation gauges – fell from a secure device on a truck which travelled from a mine site north of Newman in Western Australia’s Pilbara region to a depot in the capital Perth.
The truck bearing the capsule left the mine on 12 January, arriving in Perth on 16 January, but the capsule wasn’t discovered missing until nine days later when the secure housing was opened on 25 January.
It is believed a bolt securing the lead-lined gauge containing the capsule worked loose somewhere on the journey – potentially shaken loose by the vibrations of the truck – and the capsule fell through a hole left by the missing bolt.
Dfes has deployed teams with radiation detection devices and metal detectors along critical sections of the freight route.
David Gill, a chief superintendent at Dfes, told a press conference on Saturday emergency services crews were undertaking a “concerted, coordinated” search for the capsule.
“There are challenges here. It is 1,400 kilometres between the mine site … and Perth.
“There is the potential that we may not find this,” he conceded. “That is possible.”
The capsule’s radioactive material, which emits both gamma and beta rays, has a half-life of 30 years. Close exposure could result in burns; more sustained exposure could lead acute radiation sickness and there is the long-term risk of cancer.
Standing within a metre of the capsule is the equivalent of receiving 10 X-rays in an hour, health authorities have warned, urging anybody who finds it not to pick it up or go near it.
Darryl Ray, a superintendent with Dfes, said the search was being concentrated on populous areas north of Perth and strategic sites along the Great Northern Highway.
“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.”
Authorities are also using the truck’s GPS data to determine the exact route the driver took on the 1,400km journey – a distance equivalent to that from London to Budapest.
But there are concerns the tiny solid capsule may have already become lodged in another vehicle’s tyre and could be hundreds of kilometres from the search area.
In a statement on Sunday, Dfes said specialised equipment has been obtained from Australia’s federal government and plans were being enacted “to best search such a large area”.
“This equipment will allow the search to be conducted from moving vehicles. Presently the search involves the use of portable radiation survey meters to detect radiation levels across a 20-metre radius which will help to locate the capsule.”
Western Australia’s chief health officer, Andrew Robertson, defended the state government’s decision to wait two days to inform the public on Friday, saying the mine and depot had to be searched and excluded, and the route confirmed.
He said the capsule was packed in accordance with the radiation safety transport and regulations inside a box bolted on to a pallet.
“It is unusual for a gauge to come apart like this one has.”
An investigation will examine the handling of the gauge and capsule at the Rio Tinto mine site, the transport route taken, and the procedures at the depot in Perth after it arrived on 16 January.
Police have determined the incident to be an accident and said no criminal charges were likely.
Authorities has also ruled out theft at the depot before the box was opened, saying there was anti-tampering tape on the box.
Robertson said if someone held the capsule, or kept it close to them, “you could end up with skin damage including skin burns … and if you have it long enough near you, it could cause acute radiation sickness”.
“If you’re exposed to this one of the long-term risk of exposure to a source like this is cancer.”
“Our concern is someone will pick it up, not knowing what it is, think this is something interesting [and] keep it,” Robertson said.
• This story was amended on January 29. An earlier version said the radiation source was 19 becquerels, the correct figure is 19 gigabecquerels.
