THE Territory's only uranium mine yesterday quietly applied to operate a sulphuric acid heat-leaching plant.

Energy Resources of Australia wants to extract up to 20,000 tonnes of low-grade uranium oxide from stockpiles.

Acid would be washed through the ore from a sprinkler system.

The uranium oxide would be turned into a slurry and extracted.

The application to open the plant has been lodged with the Federal Government and could take up to 18 months.

It follows revelations at a Senate inquiry that 100,000 litres of contaminated water was leaking from Ranger's tailings dam into the ground beneath Kakadu National Park every day.

Acting supervising scientist for the Alligator Rivers region David Jones said that the seepage did not pose a threat to the surrounding environment.

Conservationists yesterday said the heat-leaching proposal threatened Kakadu's wetlands.

Spokesman Dave Sweeney said: "This is not responsible industry practise and will exacerbate the existing pressure and increasingly obvious management deficiencies at Ranger."

He said it was "shameless and unacceptable" that Ranger was seeking Government approval to expand.

"Kakadu is our largest national park, not an industrial test site," Mr Sweeney said.

"To protect Kakadu and the public interest the federal and NT governments should put this application on ice and ERA on notice."

ERA spokeswoman Libby Beath said the acid would not drain into the soil.

"The technology is not new and it's proven," she said.

Ms Beath said heat-leaching had been used at a uranium mine in a high-rainfall part of Brazil without ill effects.