It is understood up to 1.5 million litres of radioactive slurry - a mixture of mud, water, uranium ore and acid - spilled when a leaching tank split open.

Energy Resources of Australia (ERA) denied reports of an explosion, but the tank burst with such force a crane was toppled and twisted and other infrastructure was damaged.

Workers were evacuated and production could be shut down for months. ERA had been involved in tense negotiations with the Gundjeihmi Aboriginal Corporation, which represents the local Mirrar people, about expanding production to a new area that would greatly extend the life of the resource.

Gundjeihmi chief executive officer Justin O'Brien said yesterday the traditional owners could not consider any further mining at this time.

"This is nothing but a hillbilly operation, run by a hillbilly miner with hillbilly regulators," Mr O'Brien said. "Based on the woefully inadequate government response to the previous incident, we have no confidence that this will be taken seriously enough.

"This is very bad news for (shareholders)." Mr O'Brien told the Sunday Territorian that people in communities like Mudginberri, which is about 7km downstream of the Ranger mine, no longer felt safe.

It now appears traditional owners, who have made millions from uranium mining over the past decades, are set to turn against the industry.

"How can we trust the assurances of a company which has repeatedly failed to safely manage this highly toxic material?" Mr O'Brien said.

The incident is the latest in a growing list of spills, leaks and licence breaches since Ranger opened in 1980.

Last month, four uranium barrels believed to come from the mine were mysteriously found in bushland in Darwin's rural area.

Earlier in November, a mine vehicle was removed from a controlled and contaminated area without authorisation. In 2009, a dam reportedly collapsed, spilling six million litres of radioactive water into creeks feeding Kakadu.

ERA general manager of operations Tim Eckersley released a statement yesterday that said the spill was contained on site and there was no environmental impact.

Mr Eckersley said the tank was about 1450 cubic metres - capable of holding about 1.5 million litres of slurry - but the company would not say if it was full at the time.

Workers were evacuated about 1am when a hole was discovered in the leaching tank.

The tank then split, spilling the radioactive slurry and knocking down a crane that had been blocking the original hole.

"Containment systems stopped the flow and this has meant there is no impact to the surrounding environment," Mr Eckersley said.

"ERA is focusing on clean up and recovery and the protection of the environment; the health and safety of our people remains paramount."

Environmental groups yesterday called on the mine to be shut down.

"Ranger is ageing, failing and risking and (ERA parent company Rio Tinto) need to match their corporate rhetoric with action," the Australian Conservation Foundation's Dave Sweeney said.

Greens Senator Scott Ludlam said the spill should "be the last nail in this accident-prone mine".

Federal Environment Minister Greg Hunt ordered an immediate clean-up and investigation into the spillage.

WORRYING HISTORY - Incidents at the Ranger Uranium Mine have included:

• November 18, 2013: Four uranium barrels, believed to be from the Ranger mine, are found at Noonamah in Darwin's rural area.
• November 3, 2013: A mine vehicle bypassed security and left a controlled and contaminated area at Ranger without authorisation.
• 2009: A dam reportedly collapsed, spilling six million litres of radioactive water into creeks which flow into Kakadu.
• 2004: The mine was forced to shut down for eight days and ERA was prosecuted after uranium was found in the mine's drinking water and at the nearby Jabiru airport.