An investigation into the disappearance of a potentially deadly radioactive mining capsule in outback Western Australia has concluded with no charges or fines laid.
The item, measuring 8mm by 6mm, fell out of a density gauge while being trucked from a Rio Tinto mine in the Pilbara region to Perth in January.
Search crews 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 from prolonged exposure
The capsule was eventually found two metres from the Great Northern Highway by specialist equipment designed to pick up emitted radiation.
The truck arrived in the Perth suburb of Malaga on January 16 but it was not until nine days later that a technician realised the capsule was missing.
The missing capsule sparked international headlines and national media coverage in addition to widespread interest in WA.
An investigation by WA's Radiological Council found no charges or fines should be laid.
"Supported by the Department of Health, (we have) conducted a comprehensive investigation into the ... 'missing radioactive capsule incident'," the council's chair Andrew Robertson said in a statement.
"The Council has reviewed the matter of potential breaches of the Radiation Safety Act and Regulations and no charges or fines have been raised in relation to the matter at this time."
Dr Robertson said the next steps would be a review of the "specific, technical aspects" of the incident.
"Recommendations have been made about areas for improvement in gauge design and assessment and in transport of radioactive sources in WA," he said.
Under the Radiation Safety Act, the council said it could not release details of the investigation to "maintain security and public safety".
"The incident was a rare event which has implications for other radiation safety bodies," Dr Robertson said.
The Department of Health said it was sharing the findings with other jurisdictions to ensure the incident did not happen elsewhere.
Under WA laws, the maximum fine for failing to safely store or transport radioactive material is $1000.
In February, WA Health Minister Amber-Jade Sanderson said the government was looking at increasing the outdated and "unacceptably low" penalty.
Ms Sanderson said she accepted the findings and the "series of unfortunate events" that led to the capsule going missing.
"I was surprised by the findings myself but this is a group of experts ... and that is their findings and we have to accept those findings," she told ABC Radio Perth on Thursday.
WA Premier Roger Cook said he also accepted the findings of the council's investigation.
"This was an unfortunate set of circumstances, but no one is essentially guilty of neglect," he said on Thursday.
He said the state government was looking at the Radiation Safety Act to ensure the "penalties match expectations".
