A tank at the Rangers uranium mine in Kakadu National Park split, spilling radioactive materials made up of acid, ore, mud and water. Rio Tinto's (ASX: RIO) Energy Resources Australia (ERA) owns the mine.

While ERA spokesman Dan Hall admitted the slurry material is radioactive, ERA General Manager of Operations Tim Eckersley said the company's containment systems stopped the flow, resulting in no impact on the surrounding environment, and the firm is focusing on clean up and recovery.

The park is in the Northern Territory and is Australia's largest national park with more than half aboriginal land.

YouTube/National Territory, Australia's Outback

The accident led the Greens party to push for the indefinite suspension of the mine's operation and called on ERA to conduct a full audit of the plant's operations.

The Gundjeihmi Aboriginal Corporation (GAC), which represents tradition owners of the land, likewise call for an independent probe of the accident, following eyewitness and photo description of the tank explosion as causing it to bend and twist nearby infrastructure and coat the equipment with millions of litres of radioactive slurry.

Justin O'Brien, chief executive officer of GAC, called it one of Australia's biggest nuclear accidents.

Australian Greens Senator Scott Ludlam said the accident is proof that Environment Minister Greg Hunt should not deregulate the uranium sector and leave policy and decision making to states and territories.

"The writing has been on the wall at Ranger for a long time, this disaster may well be the last nail in this accident-prone mine," he said in a statement, since it is the third security breach at Ranger in just over one month.

YouTube/justin tutty

However, Professor Steve Lincoln, a uranium expert at the University of Adelaide, said the slurry is likely to have a low level of radioactivity since uranium ore is broken down when mixed with sulphuric or nitric acid which is part of the uranium refining process.

He said at the current level, radioactivity is not a worry, but acid should because of the strength of sulphuric acid.

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