Hunt in Australian Outback for a tiny, radioactive capsule

Mining giant Rio Tinto scrambles to find a dangerous capsule that fell off a truck in Western Australia

Today's expression: Set off
Explore more: Lesson #550
February 27, 2023:

A radioactive capsule the size of a pencil eraser fell of a truck in Western Australia. The capsule was part of a machine used in mining for iron ore. That led mining giant Rio Tinto and the Australian government to search a 1,400-kilometer stretch of desolate highway, searching for something the size of a pea. Plus, learn the phrasal verb "set off."

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Have you ever lost an Airpod or an earbud? Well the mining company Rio Tinto lost something that’s only a tenth the size of a single Airpod. They lost it somewhere in the Australian Outback. And they really, really needed it back.

Lesson summary

Hi there everyone, I’m Jeff and this is Plain English, where JR and I help you upgrade your English with current events and trending topics. This is lesson number 550 on Monday, February 27, 2023.

Coming up today: Rio Tinto is a global mining company. They had a piece of machinery in Australia that needed to be fixed. So they shipped the machine from an iron ore mine to Perth, the biggest city in Western Australia. Along the way, a small piece of the machine fell off the truck. It was a capsule, measuring just 8 millimeters by 6 millimeters.

But this capsule had radioactive material that could seriously harm anyone who happened to pick it up. So Rio Tinto had to search a 1,400-kilometer highway to find something less than a tenth the size of an Airpod. On today’s lesson, I’ll tell you how that went—and whether they found it.

Rio Tinto and the search for a radioactive capsule

Cesium-137 is a radioactive metal that releases beta and gamma radiation. Industrial gauges use tiny capsules of cesium-137 to measure the density of certain materials.

Rio Tinto is a mining giant with operations in Western Australia, a state in Australia. Western Australia is enormous—ten times the size of Britain, with almost all its 3 million residents in one city and its surroundings.

And in one of its mines in Western Australia, Rio Tinto had a machine that needed repair. The machine measured the density of iron ore, and that machine included a cesium-137 capsule. Rio Tinto hired a third-party transportation specialist to carefully pack up the machine, load it onto a truck, and drive it 1,400 kilometers to Perth, the state’s largest city. The machine arrived on January 16, 2023.

On January 25, the company discovered the machine was missing a piece—the cesium-137 capsule. It’s the size of a pencil eraser. But because the capsule contained a radioactive material, Rio Tinto couldn’t just forget about it. They needed to get it back.

Two days later, on January 27, an urgent public announcement was made: the capsule was dangerous, and anyone who saw it should stay at least five meters away and call authorities.

It’s not accurate to say that people were panicking, but there was concern among the residents of this area. The overall risk to the public was minimal. This part of Australia is extremely remote; the population is very small. The chances of someone stumbling across this capsule were very small.

But they weren’t zero. The capsule could have been lodged in the treads of a tire, for example. Or someone might have found it after pulling over to rest on the side of the road. There were two risks to human health. The first was exposure. If someone were standing near the capsule for an hour, that person would receive the equivalent of 17 X-rays; that’s not a deadly dose, but it’s not healthy either.

The other risk was a radiation burn. If the capsule broke apart, it could contaminate the soil or come into contact with a person’s skin. If that happened, it could cause serious radiation burns and permanent damage to a person’s skin.

So Rio Tinto had to search the Australian outback for something the size of a pea.

Luckily, they had some clues. First, they knew the capsule was in the machine when it left the mine. That means that it almost definitely fell off the truck during the journey. Most of the journey was along a single, long highway: the Great Northern Road. And the truck carrying the machine was equipped with GPS, so authorities could trace the exact route the truck followed.

Still, that left a large area to search. The capsule could have been anywhere along the side of a 1,400-kilometer road. But the other clue was this: as a radioactive substance, cesium-137 almost announces its location to anyone who has the right equipment.

So a team from Rio Tinto set off in slow-moving vehicles equipped with radiation detectors. They were driving in a car at 70 kilometers per hour when they saw spikes in the radiation detectors. They stopped and performed a more detailed search with yet more complicated equipment.

That’s when they finally located the capsule. It was just a few meters off the side of the road in a desolate stretch of highway , far away from the nearest town. It’s unlikely that anyone got anywhere near it.

Apology accepted

What a search: They were looking for something the size of a pencil eraser in the Australian outback!

It shouldn’t have been necessary, but it was a pretty good success story. A spokesman for Rio Tinto apologized—as well he should!—and said the company would reimburse the government for the cost of the search.

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Expression: Set off