Radioactive capsule site cleared of contamination

It was recovered on Wednesday following days of searching after it fell out of a density gauge while being trucked last month from a Rio Tinto mine in the Pilbara to Perth.

WA's Department of Fire and Emergency Services said the Australian Defence Force had verified the capsule using its serial number.

It was placed in a lead container and transported to a secure location in Newman and was to be moved to a WA Health facility in Perth on Thursday.

The site had been surveyed and cleared of any residual radiological contamination and there was no need to remediate the area, the department said.

A 20m "hot zone" was established around the capsule during its recovery.

Search crews had spent six days scouring a 1400km route amid warnings the Caesium-137 in the capsule could cause radiation burns or sickness if handled and potentially dangerous levels of radiation with prolonged exposure.

"Locating this object was a monumental challenge," Emergency Services Minister Stephen Dawson told reporters.

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

The capsule was detected by a vehicle travelling at 70km/h when specialist equipment picked up emitted radiation.

Portable detectors were used to locate it two metres from the side of the road.

A government investigation has been launched into the incident.

Rio Tinto has apologised and is also reviewing what went wrong during the haul, which was carried out by a contractor.

It said a bolt that secured the capsule within the gauge appeared to have sheared off, creating a hole big enough for the item to fall out.

The truck arrived in the Perth suburb of Malaga on January 16 but it wasn't until nine days later that a technician realised the capsule was missing.

The maximum fine in WA for failing to safely store or transport radioactive material is just $1000.

Health Minister Amber-Jade Sanderson on Wednesday said the government was looking at increasing the outdated and "unacceptably low" penalty.

Rio Tinto iron ore chief executive Simon Trott said the mining giant would fully co-operate with investigations and was willing to reimburse the cost of the search.