Missing radioactive capsule found in WA outback after frantic search

A tiny but potentially deadly radioactive capsule has been found in WA’s outback, after it sparked a frantic search and unprecedented public health warning spanning hundreds of kilometres.

Key points: The radioactive capsule was found just outside Newman

The radioactive capsule was found just outside Newman Its loss sparked an unprecedented public safety warning over 1,400km

Its loss sparked an unprecedented public safety warning over 1,400km It had been likened to 'finding a needle in a haystack'

WA Emergency Services Minister Stephen Dawson said it was found 74km south of Newman on the Great Northern Highway this morning.

"I do want to emphasise this is an extraordinary result," he said at a press conference on Wednesday afternoon.

"The search crews have quite literally found the needle in the haystack."

The capsule was found by a team from the Australian Nuclear Science and Technology Organisation and the Department of Fire and Emergency Services.

A map showing the approximate location of where the capsule was found. ( ABC News )

Capsule found near side of the road

The Fire and Emergency Services Commissioner, Darren Klemm, said the capsule was found two metres from the side of the road.

He said a search vehicle was driving past at 70 kilometres per hour on the Great Northern Highway when a detection device revealed radiation.

The stretch of Great Northern Highway where the capsule was found on Wednesday morning. ( Suppllied: DFES )

A 20 metre "hot zone" has been set up around the capsule to ensure the public's safety and it will be placed into a lead container.

The capsule will be stored at a secure location in Newman overnight before being transported to a WA Health Department facility on Thursday where it will be examined.

"In the extremely unlikely situation that the capsule leaked, we will remediate the area," Commissioner Klemm said.

An urgent public warning was issued after the caesium-137 capsule was reported missing on January 25 when it apparently fell off a truck transporting it from a Rio Tinto mine to Perth.

The missing capsule that prompted an emergency warning over a 1,400km stretch of Western Australia. ( Supplied: DFES )

It vanished between January 11 and January 16, but its loss was not reported for more than a week.

The capsule which measures 6mm in diameter by 8mm in height is used in mining equipment but can lead to dangerously high doses of radiation if mishandled.

Western Australians were warned of the missing capsule in an extraordinary press conference held late on Friday afternoon.

Commissioner Darren Klemm says the area around where the capsule was found will be remediated. ( ABC News: Jessica Warriner )

The state's Chief Health Officer Andy Robertson warned at the time it could be anywhere between Perth and the Pilbara, an area stretching for 1,400 kilometres.

Capsule hadn't moved after falling off truck

Dr Robertson said it was a great result the capsule had been found because although it was tiny, it "did pose a significant public health risk".

Searchers at the site where the radioactive capsule was found. ( Supplied: DFES )

Dr Robertson said the capsule did not appear to have moved after falling from the truck which was transporting it and it was pleasing no one had been harmed.

He said he would now be investigating all aspects of the event to make sure the capsule was appropriately managed.

"We have the ability to prosecute under the radiation safety act and we will certainly look at such prosecutions, and we've done that in the past," he said.

WA's chief health officer Andy Robertson holds up a diagram of the radioactive capsule alongside a 10c coin. ( ABC News )

The investigation was expected to take "a number of weeks" at least.

The Prime Minister, Anthony Albanese, this morning joined those disappointed to learn the maximum penalty for mishandling radioactive material in such a manner was $1,000.

"It shouldn't have been lost, that's the first thing. And second, yeah of course that figure is ridiculously low," Mr Albanese said.

Higher penalty won't be applied retrospectively

Stephen Dawson said the government was looking at updating the relevant act but said there would be no opportunity to retrospectively issue higher penalties.

"Let's wait and see what happens with the investigation as to who we can apportion blame to," Mr Dawson said.

"But certainly, I do want to state Rio Tinto have been exceptional in terms of how they have reached out to us and offered all levels of support, so I'm very grateful for that offer from Simon Trott."

The caesium-137 radioactive source was part of a radiation gauge commonly used in processing plants, and was being transported from a Rio Tinto mine site in WA's north to a depot in Perth for repairs.

Rio Tinto 'happy' to pay search costs

Speaking after the capsule had been recovered, Rio Tinto's Chief Executive of Iron Ore, Simon Trott, said the company would reimburse the state for the search if asked to.

"I would be happy to reimburse the cost of the search, of course that ultimately is a matter for the state government," he said.

"There will be a full investigation, we'll fully cooperate with the investigation, if as part of that there's a request from government, we would be happy to reimburse the cost of the search."

Rio Tinto's iron ore chief Simon Trott said the company would cooperate with any investigation into the loss. ( ABC News )

Mr Trott also thanked all of those involved in the operation and apologised for the loss of the capsule.

"Of course, the simple fact is that this device should never have been lost, we're sorry that occurred, and we're sorry for the concern that has caused for the WA community," he said.

"We need to learn from this so we can put in place additional controls to ensure that this never happens again."

It was not yet clear what the final cost of the search exercise was expected to reach, but the government admitted it had been "costly".

"Over the last few days, we've probably had about 100 personnel involved in the search," Stephen Dawson said.

"That includes career and volunteer fire fighters, it includes WA Police, it includes people from the Health Department and of course over the last few days in particular it includes people from the ADF."

The missing capsule attracted global attention and was even mocked on US talk show The Late Show with Stephen Colbert.

The Australian Defence Force has verified the capsule using its serial number.

East Pilbara Shire President Anthony Middleton said the lucky discovery was welcome news.

"I think it was done very well, DFES have done a magnificent job," he said.

"To locate such a small item along 1400km of highway is absolutely amazing."

He said there has been some initial concern in the Newman community that reduced once relevant information was made public.

A 3D printed replica of a missing radioactive capsule that was lost in transit in Western Australia. ( ABC News: Kenith Png )

"There's a little bit of angst and animosity – at the start we didn't know where it had come from," he said.

"It put people at ease slightly knowing that it would have been a transport company that would have driven past town."

But he backed reforms to the WA laws governing the safe transport and storage of other radioactive material.

"I thought it would have been a little bit more stringent – the practices of transport will be heavily scrutinised after this, that's for sure," Mr Middleton said.