Medical production at the facility has ceased, pending a thorough investigation into the spill, the spokesman said. "ANSTO is working to minimise impacts on nuclear medicine production.”

ANSTO was keen to stress that Thursday's incident was "very different" from one last August, when a staffer reportedly spilled a quantity of the MO-99 isotope, causing a "significant radiation dose".

“Tests show the analyst involved in yesterday’s incident did not receive skin contamination. ANSTO continues to provide support for the employee involved in last year’s incident.”

The site has had other radiation events, such as one reportedly involving four staff in 2012.

ANSTO said about one in every two Australians will need a dose of nuclear medicine in their lives, with the material used for diagnosis and treatment of various heart, lung, brain and bone conditions, as well as cancer.