Key Points
- A unit in Sydney has been declared safe after the removal of low-level radioactive isotopes.
- Radioactive isotopes are commonly used in medicine.
- How dangerous they are depends on the quantity, according to experts.
A unit in Sydney has been declared safe after low-level radioactive isotopes were removed by NSW Fire and Rescue and Australian Border Force (ABF) officers.
The ABF said it had seized 52 vials of potentially hazardous materials from the home, after officers detected a range of illicit substances being imported through air cargo in Sydney.
It said the vials have been transferred to the appropriate facilities, where they will be subject to testing.
"A 23-year-old Australian national male is assisting with investigations, which remain ongoing," the ABF said in a statement on Friday.
"At this time, there is no evidence to suggest that this incident poses any kind of national security risk."
Specialist crews located low-level radioactive isotopes, commonly used in several industries, at the unit on Thursday, NSW Fire and Rescue said.
A spokesperson said the material was found in suitable and effective containers, with no release of radiation. Three people were taken to hospital for observation.
Channel 10 reported that authorities found the substance isotope uranium 238.
Australian Border Force officers at the Sydney unit on Thursday. Source: AAP / Bianca De Marchi
What are radioactive isotopes?
Radioactive isotopes, typically shortened to 'radioisotopes' are the unstable form of an element that emit radiation to transform into a more stable form, explains the International Atomic Energy Agency.
Radiation is easily traceable and can cause changes in the substance it falls upon, which makes radioisotopes useful in medicine, industry and other areas.
Just because an element has isotopes, they're not all radioactive, Obbard told SBS News.
"Uranium is special because all the isotopes of uranium are radioactive."
Uranium 238, which is the most common type of uranium, has a half-life of four-and-a-half billion years.
Half-life means approximately the average time you have to wait for an atom to decay into something else.
"Because it has such a long half-life it's actually quite stable because it's decaying so slowly," Obbard said.
Uranium is naturally occurring and may show up in substances such as rocks, he said.
How dangerous are radioactive isotopes?
Uranium 238 is not dangerous in very small quantities, Obbard said.
It's mainly used in nuclear reactors, Curtin University physics professor Nigel Marks told SBS News.
"It's hard to think of why a civilian would have some uranium, perhaps someone gave it to them from a piece of rock from a mine.
"It could be what's called yellow cake, which is uranium oxide exported by Australia," he said.
"If it is just a piece of, say, uranium metal, you know, in a small plastic vial, then you could have it sitting next to you and just stare at it wouldn't do you any harm at all. So it's just it's a, it's purely a question of quantity."
Uranium can be detected in some old glassware, that was deliberately made with uranium in a metal form because it glowed in the dark.
Similarly, it can be used in yacht keels because it's very heavy.
How are radioactive materials regulated in Australia?
Any amount of radioactive material heavier than 800 milligrams must be licensed in Australia.
While the Sydney property has been declared safe, this case raises concerns about radioactive material security, Obbard said.
"They're are three types of nuclear regulations: nuclear safety, nuclear security and nuclear safeguards, and all three of these types of regulations apply to uranium," he said.
"This whole story is significant for nuclear security because you have a radioactive material that probably should be licensed, and has gone outside that control system and out in the community."
In January authorities spent days searching for a tiny but dangerous radioactive capsule from a Rio Tinto mine after it disappeared on a 1,400km truck journey across the outback before eventually finding it.
