An investigation into the lost capsule has cleared mining giant Rio Tinto of any wrongdoing

An investigation into how a tiny radioactive capsule went missing before it was found in an intensive search has found mining giant Rio Tinto was not at fault.

An investigation into how a tiny radioactive capsule was lost while being transported in outback Western Australia earlier this year has cleared mining giant Rio Tinto of any wrongdoing.

On Thursday, the miner said the Western Australian Radiological Council, which had been investigating the incident, had not identified any breaches of WA’s Radiation Safety Act by the company.

“We are grateful to the state and federal governments and all of those involved in the successful recovery of the capsule,” a Rio Tinto spokesperson said.

“Our own internal review has identified opportunities for improvement in the selection of radiation gauges and the way they are packaged and transported.”

The radioactive capsule was smaller than a 10c coin. Picture: DFES

The capsule – which could fit onto a 10 cent piece – came loose during transportation from north of the Pilbara mining town of Newman to the Perth suburb of Malaga sometime between January 10 and January 16.

It was found nearly two weeks later after a search along a 1000km stretch of road not far from where it started its journey at a Rio Tinto mine.

An investigation by Western Australia’s Radiological Council, chaired by Chief Health Officer Andrew Robertson, is continuing.

“The investigation is led by the Radiological Council of WA with support from the Department of Health’s Radiation Health Branch.

“The council continues to consider issues stemming from the investigation, for consideration to provide input into updates of national safety standards.”

He said amendments to penalties under the Radiation Safety Act were also under consideration, after it was revealed the maximum fine which could have been imposed was $1000.

The capsule, though tiny, contained a large radiation does. Supplied/Radiological Council WA

The loss of the tiny capsule made world headlines.

The small, round, silver capsule, 6mm in diameter and 8mm high, is used within gauges in mining operations and contains a small quantity of radioactive Caesium-137.

Dr Robertson said despite its size, the capsule contained “quite a large radiation dose”, which

was like “receiving around 10 X-rays an hour,”

It was packed onto a pallet at Rio Tinto’s Gudai-Darri mine site on January 10, with the pallet loaded onto the back of a semi-trailer and left the site for Perth between January 11-14.

It arrived at a radiation service company in the northern suburb of Malaga on January 16, but the capsule wasn’t noticed missing until the pallet was unpacked a couple of days later.

Rio Tinto provided a mobile worker camp to help rebuild flood-damaged Fitzroy Crossing, in lieu of payment for the cost of the massive search for the capsule.

Chief executive Simon Trott said at the time the $4m cost was worth more than the cost of the search.

“We really want to support the efforts to rebuild the Kimberley following those devastating floods,” he said.

“[We‘re] really pleased to have worked with the state government to bring forward this solution, to honour our commitment to pay for the search for the capsule.”