Authorities examining a remote Australian highway have found a small missing radioactive capsule at the side of the road, after a difficult search that is like trying to find a needle in a haystack.
State emergency authorities announced the discovery Wednesday afternoon, six days after the capsule contained highly radioactive cesium-137. Missing from a parcel sent hundreds of kilometers from the Rio Tinto mining site in northwest Australia to the capital, Perth.
“Locating this object has been an enormous challenge – search groups have literally found the needle in the haystack,” state emergency services minister Stephen Dawson said at a press conference on Wednesday.
The capsule’s disappearance sparked a full-scale highway search with specialized radiation detection units – and prompted warnings to the public not to go near the capsule, which could cause serious burns on contact with the skin.
Authorities believe the capsule — about 8 millimeters high and 6 millimeters round — somehow fell from the back of a truck while it was being transported 1,400 kilometers (870 miles) along the Great Northern Highway from the mine.
Rio Tinto, which has been using the device on scale at its Guday Dare iron ore mine, said it regularly transports and stockpiles dangerous goods as part of its business and employs expert contractors to handle radioactive materials.
In a statement on Wednesday, CEO Simon Trott said the company was “extremely grateful” for the work that was done to find the capsule and once again apologized to the community for its loss.
“While the recovery of the capsule is a great testament to the skill and perseverance of the research team, the truth is that it should never have been lost in the first place,” he said. “We are taking this incident very seriously and are conducting a full and thorough investigation into how it happened.”
Authorities said the missing capsule was discovered at 11:13 a.m. local time on Wednesday, two meters down the road just south of the small town of Newman by crews using radiation detection equipment.
Officials said a 20-meter exclusion zone has been created around the capsule, and it will be moved to a main container before it is moved to a security facility in Newman.
On Thursday it will begin its journey south again – this time to the Department of Health facility in Perth.
Andrew Robertson, chief health officer and head of the Radiological Board, said it did not appear that anyone had been exposed to radiation from the capsule during the time it was missing.
“It doesn’t appear to have moved — it appears to have fallen off the track and landed on the side of the road. It’s far enough away that it isn’t in any large community, so it’s unlikely that anyone would be exposed to the capsule.”
Washington State’s Department of Emergency Services (DFES) sounded the alarm on Friday, alerting residents to a radioactive leak in the state, including the northeastern suburbs of Perth, home to about two million people.
According to authorities, the capsule was placed inside a package on January 10 and collected from the Gudai-Darri mine site in Rio Tinto by a contractor on January 12.
The car spent four days on the road and reached Perth on 16 January but was only offloaded for inspection on 25 January – when it was discovered that the capsule was missing.
The incident came as a shock to experts, who said the handling of radioactive material such as cesium-137 is highly controlled with strict protocols for its transportation, storage and disposal.
WA Radiation Services says radioactive material is transported around Western Australia on a daily basis with no problems. “In this case, there appears to be a failure of control measures that would normally be applied,” it said in a statement, adding that it had nothing to do with the loss of the capsule.
DFES Commissioner Darren Clem said the capsule was found in the “best possible area” due to its remote location and finding it in such a short time was “incredible”.
“A lot of the work was done around the metro area based on some intelligence early on… So, you can only imagine there was an element of surprise to the people in the car when the equipment went up,” he said.
Cesium-137 can cause serious health problems for people who come in contact with it: burns from close exposure, radiation sickness and potentially fatal cancer risks, especially for those unintentionally exposed for long periods of time.
Robertson, the chief health officer, said standing 1 meter away from the capsule for 1 hour would be equivalent to receiving a radiation dose from 10 x-rays.
Officials feared the capsule might get stuck in the tires of another car and moved away from the search area. It could also have been taken from the area by an animal – or worse, someone picked it up and kept it unaware of the risks.
And the danger was not only in the short term – cesium-137 has a half-life of about 30 years, which means that after three decades the radioactivity of the capsule will be halved, and after 60 years it will decrease again, which means that it will be lost. The capsule can remain radioactive for up to 300 years.
Robertson said it was unlikely that the capsule had contaminated the surrounding soil because it had been left unattended for days on the highway.
“It is encased in stainless steel, so there is unlikely to be any contamination in the area unless there is significant damage to the actual source itself, which is unlikely due to a fall from the back of a truck.”
Robertson is investigating the capsule’s disappearance and will report to the Minister for Health in the coming weeks.
Dawson, the emergency services minister, said the capsule’s recovery was an “extraordinary result”.
“I think Western Australians can sleep better tonight,” he added.
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