Environmental costs: In a new study, scientists question the sustainability of nuclear power because of anticipated declines in high-grade uranium ore. Above is Australia's Ranger uranium mill in Kakadu National Park.

Credit: Gavin M. Rudd

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SYDNEY: The case for nuclear power as a sustainable alternative energy source is challenged by new evidence that greenhouse gas emissions from uranium mining are increasing.

An Australian report, detailed this week in the journal Environmental Science and Technology argues that the availability of high-grade uranium ore will deplete over time making the fuel more environmentally and economically expensive to extract.

The find adds to existing concerns about nuclear energy, such as the problems of disposing of radioactive spent fuel and whether uranium processing leads to the proliferation of nuclear weapons.

Increasing environmental cost

"Commonly in the mining industry, as higher grade ores are mined, lower grade deposits become economic - but this is at increasing environmental costs such as more energy, water, greenhouse emissions, tailings and waste rock," said lead author Gavin Mudd of Monash University in Melbourne.

The 'grade' of uranium refers to how much of the element is found in the ore, an important economic factor in mining. High-grade uranium is easier to process than low-grade, and less expensive to extract, however as this is used up, the industry must turn to lower grades.

For the study, Mudd and co-author Mark Diesendorf, an environmental scientist at the University of New South Wales in Sydney, reviewed existing data on uranium mining, milling, enrichment and fuel manufacture from across the world. This included historical figures showing when most mining had occurred, contemporary financial and technical reports, and CO₂ emissions reports.

The goal of the research was to evaluate the true economic and environmental costs of uranium mining. "We wanted to know what the environmental cost regarding mineral production is in terms of greenhouse emissions, water, and energy, and we found that all of these things do increase over time," said Mudd.

"Important contribution"

He noted that, as the quality of uranium ores decrease, more trucks and other equipment are needed to refine them, which wastes more energy and resources. "This is the first time we've put numbers to this concept, rather than it being an anecdotal idea," said Mudd, "There were real numbers available, so it was time to get those numbers together."

Jim Falk, a professor at the University of Melbourne who specialises in the political, economic and cultural impacts of nuclear technology, said that the study is "an important contribution to the debate over climate change and nuclear power."

"The amount of uranium which can be utilised without creating excessive greenhouse gas emissions – and using excessive water – may be rather more limited than has been suggested," said Falk, who was not one of the study's authors. "The potential role of nuclear power, is likely to be also limited by such considerations."

Nevertheless, Falk noted that while critics argue that nuclear energy industry generates large quantities of CO₂ (sometimes calculated to be as much for a nuclear power station as an equivalent gas power station) it still generates much less than a coal-burning power plant.

"Fear campaign"

Not everyone agrees with the outcome of the report, however. Michael Angwin, the executive director of the Australian Uranium Association, an industry trade group based in Melbourne, called uranium depletion a "common myth" that amounts to nothing more than a "fear campaign."

Angwin said that the quantity of available uranium is directly related to exploration, and that as exploration increases, new uranium sources will be uncovered. And according to Angwin, Australian uranium exploration is on the rise – between 2006 and 2007 A$114 million was spent on it. He also noted that as technologies get more sophisticated, efficiency will increase, so that the same amount of uranium ore today will create a larger amount of power in the future.

To bolster these claims, the U.N.'s International Atomic Energy Agency (IAEA) reported in March of this year that known uranium resources recently increased by 17 per cent. But this figure was largely a reassessment due to expanded drilling at existing sites, Mudd said, rather than exploration at new sites.

Mudd agreed that there was a connection between exploration and known reserves, but argued that exploration is getting more difficult in that it requires increasingly deep drilling. The more significant issue is the declining grade of new uranium deposits, he said.