The Morrison government has failed to provide the $210 million needed to decommission an "unsafe" nuclear medicine facility at Lucas Heights, with money only provided towards a business case in this week's federal budget.

The decision has sparked concern for public safety, after an independent panel of experts found the building did not meet modern nuclear safety standards and called for its urgent replacement last October.

ANSTO’s nuclear facility at Lucas Heights.

"The lack of a permanent replacement solution ... is undermining the possibility of truly effective risk control," the reviewers found.

Known as "Building 23", the facility – built in the 1950s – has been dogged by accidents and near-misses in recent years, including a radioactive spill in 2017 that was then classified as the most serious incident in the world.