Australian nuclear agency joins hunt for lost radioactive capsule

People were told to stay away from the small capsule containing Caesium-137, which emits radiation equivalent to 10 X-rays per hour.

Australia’s nuclear safety agency has joined the search for a tiny radioactive capsule missing somewhere offshore, sending a team with specialized car-mounted and portable detection equipment.

The loss of the radioactive capsule, believed to have fallen from a truck traveling about 1,400 km (870 miles) across Western Australia, prompted a week-long search and a radiation alert for large parts of the state.

The Australian Radiation Protection and Nuclear Safety Agency said on Tuesday it was working with the Western Australian government to locate the capsule. The Australian Nuclear Science and Technology Organization also sent radiation services specialists as well as detection and imaging equipment.

The capsule, part of a gauge used to measure the density of iron ore, was entrusted by Rio Tinto Ltd to a specialist contractor to transport. On Monday, Rio apologized for the loss, which happened sometime in the past two weeks. The truck was traveling from north of Newman, a small town in the remote Kimberley region, to a storage facility in the north-eastern suburbs of Perth – a distance longer than the length of Britain.

Western Australia Chief Health Officer Andrew Robertson said under strict regulations, radioactive material was routinely transported through Western Australia.

“It is extremely rare for a source to be lost,” he said in a statement.

State emergency officials on Tuesday issued a new warning to motorists along Australia’s longest highway to be careful when approaching the capsule search, as vehicles carrying the radiation detectors travel along the highway at slow speeds.

“It will take approximately five days to travel the original route, an estimated 1400kms, with crews traveling north and south along the Great Northern Highway,” Department of Fire and Emergency Services (DFES) incident controller Darryl Ray said. said a statement. Monday.

The capsule was picked up from Rio Tinto’s Gudai-Darri mine site on January 12. When it was unpacked for inspection on January 25, the meter was found broken, with one of four mounting bolts missing and screws from the meter also gone.

Authorities suspect vibrations from the truck caused the screws and the bolt to come loose, and the capsule fell out of the package and then through a gap in the truck.

The silver capsule, just 6 mm (0.24 in) wide and 8 mm (0.31 in) long, contains Caesium-137 which emits radiation equivalent to 10 X-rays per hour. People were told to stay at least 5 meters (16.5 feet) away as exposure could cause radiation burns or radiation sickness, although experts said driving past the capsule would be a relatively low risk, similar to taking An X-ray.

A Western Australia Department of Fire and Emergency Services image on January 27, 2023 shows the size of a small capsule containing Caesium-137 compared to a 10p coin [EPA-EFE/DFES]

The capsule does not pose a danger to passers-by who do not linger, said Edward Obbard, senior lecturer in Nuclear Engineering at the University of New South Wales, Sydney.

“If you stood a meter away for an hour, you would receive a radiation dose of about 1 millisievert. This is about one-twentieth of the dose that people working with radiation are allowed to receive in a year,” Obbard wrote in The Conversation.

“If you were much closer to the capsule, say 10cm or so, you’d get about 100 millisieverts per hour, which could do you real damage,” he said.

If the capsule remains missing, it will pose a danger for “the next century or so,” according to Obbard. The concern is that such a threat may be forgotten over time.

“Will anyone remember?” Obbard asked

“If you came across a tiny cylinder on the road today, you’d know to keep your distance – but what if you found it in five years, or 20 years?”