An independent radiation safety expert from Queensland, who was called in to speak to Ranger uranium mine employees this week about exposure levels, says management is reassessing its procedures.

The mine's union expressed concern after a dirty clean up job at the mine three weeks ago.

Mark Sonter says the mine's general manager asked him to provide an independent perspective to employees on radiation levels after about a dozen men were exposed to uranium oxide when clearing out a hopper in October.

Mr Sonter says the six men tested showed a very low level of chemical intake which probably happened when they washed after the job.

"By getting a bit on their lips while showering after or brushing a still dirty hand on their face while showering or something like that," he said.

Mr Sonter says he has told the men that the five micrograms of uranium per litre of urine that were detected is far below what constitutes a health or radiation risk.

"The level in urine which relates to some sort of health risk is in the 100s or micrograms per litre and it is known from old, old, old occupational hygiene scientific literature that 2000 micrograms per litre is the level at which you start worrying about permanent kidney damage or things like that.

Mr Sonter says a safety review was done before the job and all the men were wearing the correct respiratory protective gear.

He says he has assured the men the exposure levels are at the lowest end of the scale.

He says the mine's management and supervisors are now rethinking the safety procedures for such jobs.

Mr Sonter says about 40,000 Australian workers deal with radiation and the Ranger mine workers are exposed to average levels.

"The average is that they all get about a tenth of the annual limit or maybe a bit more, so our uranium miners up here in the Territory are spot on the average for radiation workers throughout Australia," he said.