The Australian Department of the Environment has cleared Ranger uranium mine and its operator Energy Resources Australia (ERA) from last year’s radioactive leak and acidic slurry at the mine.

According to the interim report released by the department, the leak that took place at the mine in December did not have any significant impact on humans or the environment.

The workers involved in clean-up operations were exposed to low radiation, which will have no consequence to human health, it added.

ERA, a subsidiary of Rio Tinto, expects to reach normal production levels in the third quarter of the year and production capacity of up to 1,500t of uranium oxide by year end, reported Mining.com.

The collapse of a leach tank at the Ranger mine on 7 December last year resulted in spilling of around 1,400m³ of slurry containing ground uranium ore, water and sulphuric acid into the processing area.

Though no one was injured in the incident, a Ranger Minesite Technical Committee was formed to undertake investigations.

Production at the mine was stopped after the incident.

"The leak that took place at the mine in December did not have any significant impact on humans or the environment."

The environmental impacts of the incident were studied by the Office of the Supervising Scientist, which monitored both onsite and offsite sampling, analysis of surface water, groundwater, radiation and soils.

Geoscience Australia studied the impact on groundwater.

Supervising Scientist found that the leach tank failure did not have an adverse impact on human health or the nearby environment, including Kakadu National Park.

The investigators also found that workers, who cleaned the mine after the incident, were not highly exposed to radiation and did not report any health problems.

The Northern Territory Department of Mines and Energy and Northern Territory WorkSafe are investigating the cause of the leach tank failure and the condition of the Ranger processing facility.

The technical committee has ordered ERA to provide an implementation plan to address issues related to groundwater monitoring reported by Geoscience.

Image: Energy Resources Australia-operated Ranger uranium mine is located in the Northern Territory of Australia. Photo: courtesy of Geomartin.