A staff member at the Australian Nuclear Science and Technology Organisation facility at Lucas Heights has been involved in a spill of radioactive material, the second such incident in 10 months.

A quality control analyst working in medical production was involved in the spillage of about one millilitre of the radioactive isotope molybdenum-99 early on Thursday morning, an ANSTO spokesman said.

The nuclear reactor at ANSTO's Lucas Heights research campus. Credit:Sahlan Hayes

“The staff member was wearing full protective clothing. An occupational health physicist checked the analyst and confirmed no skin contamination," the spokesman said.

The employee was then cleared to go home and returned to work on Friday.