CNN: Search in Australia for missing radioactive capsule

It’s like looking for a needle in a haystack – an 8mm by 6mm silver capsule, no bigger than a coin, believed to be lost somewhere along a stretch of vast desert highway in Australia’s biggest state.

Mining company Rio Tinto issued an apology on Monday saying it was supporting state government efforts to find the capsule, which contains Caesium-137, a highly radioactive substance used in mining equipment.

Rio Tinto said it has checked all roads in and out of the Gudai-Darri mine site in remote northern Western Australia, where the device was located before a contractor collected it for the journey south to the state capital, Perth.

Authorities believe the capsule, which emits both gamma and beta rays, fell off the back of a truck trundling along a 1,400 kilometer (870 miles) section of the Great Northern Highway – a distance longer than the Californian coastline.

Due to the tiny size of the capsule and the huge distances involved, authorities warn the chances of finding it are slim.

And there are fears that it may have already been carried further from the search zone, creating a radioactive health risk for anyone who comes across it for potentially the next 300 years.

According to authorities, the capsule was placed inside a package on January 10 and collected from Rio Tinto’s Gudai-Darri mine site by a contractor on January 12.

The vehicle spent four days on the road and arrived in Perth on January 16 but was only unloaded for inspection on January 25 – when it was discovered missing.

“Upon opening the package, it was found that the gauge was broken apart with one of the four mounting bolts missing and the source itself and all screws on the gauge also missing,” said the Department of Fire and Emergency Services (DFES).

Experts have warned Caesium-137 can create serious health problems for humans who come into contact with it: skin burns from close exposure, radiation sickness and potentially deadly cancer risks, especially for those exposed unknowingly for long periods of time.

Radiation Services WA, a company that provides radiation protection advice, says standing within one meter of the capsule for an hour would deliver around 1.6 millisieverts (mSv), as much as around 17 standard chest X-rays.

Picking up the capsule would cause “serious damage” to your fingers and surrounding tissue, the company said in a statement.

The incident has come as a shock to experts who said that handling of radioactive materials like Caesium-137 is highly regulated with strict protocols for their transport, storage and disposal.

Rio Tinto said it regularly transports and stores dangerous good as part of its business and hires expert contractors to handle radioactive materials. The tiny capsule was part of a density gauge used at the Gudai-Darri mine site to measure the density of iron ore feed in the crushing circuit, it said in a statement.

Pradip Deb, a lecturer and radiation safety officer at RMIT University in Melbourne, said the loss of the capsule was “very unusual” as Australian safety rules require them to be transported in highly protective cases.

Caesium-137 has a half-life of about 30 years, which means that after three decades, the capsule’s radioactivity will halve, and after 60 years, it’ll halve again.

At that rate, the capsule could be radioactive for the next 300 years, said Deb from RMIT University.

The name of the logistics company used to transport the device has not been released, Rio Tinto said.

Source: CNN