Saturday, February 4, 2023

At 11am on Wednesday, Authorities found a lost 8-millimetres high by 6-millimetres round capsule, containing harmful radioactive substance 19-gigabecquerel caesium-137, two meters near the Great Northern Highway, 74 km south of Newman, Western Australia (WA). Authorities verified serial number of the capsule, and then placed it in a lead container and stored it in Newman securely overnight before transporting to a WA Health facility in the state capital Perth on the next day.

The capsule was part of a gauge used to measure the density of iron ore at Rio Tinto’s Gudai-Darri iron ore mine, located in Pilbara, WA. Such device is commonly used in mining. Repair was required, and was the reason why the device needed to be transported from the iron ore to Perth. The device had been packaged on January 10, and the truck departed the iron ore on January 12. The truck arrived on January 15. Recipient reportedly unpacked the delivery on January 25, and, finding the gauge screws and one mounting bolt missing, and the gauge missing, reported the loss of the gauge to authorities. Search operations commenced on that day. Authorities declared a public health emergency on January 27. A Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) vehicle vehicle equipped with a radioactivity detection camera arrived on the evening of Monday January 30.

The radioactivity detection camera was modified version of CORIS360 from Australian Nuclear Science and Technology Organisation (ANSTO). It was on the ARPANSA vehicle moving at the speed 50 km/h. The camera made fast and high resolution 360-degree images of surroundings, identifying regions with higher values of radioactivity. ANSTO had launched the device in 2020. The relevant experts from ANSTO’s site in Lucas Heights, New South Wales traveled to Western Australia to conduct the search operation, arriving Monday evening on January 30.

Emergency Services Minister of Western Australia, Stephen Dawson, remarked on the need to re-evaluate the procedures involved, saying “How these things are transported needs to be re-looked at, I mean it does puzzle me how such a thing can fall off the back of a truck.”

Associate Professor Nigel Marks from School of Electrical Engineering, Computing and Mathematical Sciences at Curtin University remarked on unsuitable packaging for the transport. He said, “A wooden palette is not meant for radioactive confinement. Nor is the back of a truck. It’s a small object, roughly the size of a pebble, and hence could bounce anywhere.”

Authorities have attributed the loss to ‘vibrations’ during the truck drive, leading to the capsule detaching from the gauge and subsequently falling through a hole in the container, where a mounting bolt was also missing. Investigations were ongoing to assess whether the required procedures for transport of radioactive substances were followed when packing the gauge and the container, as failure to follow the required procedures may lead to prosecution. Authorities suggested increasing the relevant penalties, which included a maximum fine of AU$1,000 at that time.

Prior to the arrival of the advanced imaging equipment, the search teams were equipped with handheld devices for radiation detection and metal detection and needed to conduct the search on foot. Furthermore, public had been advised to check their car tyres in case their vehicle picked up the capsule while driving on a part of the route.

Rio Tinto’s Gudai-Darri iron ore mine had hired a Centurion truck, and SGS Australia contractor for packing and unpacking of the capsule, to deliver it from Rio Tinto’s Gudai-Darri iron ore mine to a depot in Malaga, a suburb 11 km north of Perth.

Authorities were intending to investigate the roles of the trucking and packing contractors, of the gauge manufacturer, and of the Rio Tinto iron ore for the incident. Government would also need to bill the costs of the search operations to one or more of the parties responsible for the incident.

The Rio Tinto iron ore chief executive Simon Trott remarked the company would be willing to reimburse the search operations costs if requested by the government, saying “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. We need to learn from this so we can put in place additional controls to ensure that this never happens again.”

Such a radioactive capsule, if in contact with the body for several hours, could lead to skin injuries and amputations, depending on the radioactive substance and its quantity and duration of exposure, ABC (Australia) reported.

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