[NYTr] Coal Ash More Radioactive than Nuclear Waste - Scientific Amer

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Scientific American - Dec 13, 2007
http://www.sciam.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste

Strange but True:
Coal Ash Is More Radioactive than Nuclear Waste

By burning away all the pesky carbon and other impurities, coal power
plants produce heaps of radiation

By Mara Hvistendahl

The popular conception of nuclear power is straight out of The Simpsons:
Springfield abounds with signs of radioactivity, from the strange glow
surrounding Mr. Burn's nuclear power plant workers to Homer's low sperm
count. Then there's the local superhero, Radioactive Man, who fires
beams of "nuclear heat" from his eyes. Nuclear power, many people
think, is inseparable from a volatile, invariably lime-green,
mutant-making radioactivity.

Coal, meanwhile, is believed responsible for a host of more quotidian
problems, such as mining accidents, acid rain and greenhouse gas
emissions. But it isn't supposed to spawn three-eyed fish like Blinky.

Over the past few decades, however, a series of studies has called these
stereotypes into question. Among the surprising conclusions: the waste
produced by coal plants is actually more radioactive than that generated
by their nuclear counterparts. In fact, fly asha by-product from burning
coal for powercontains up to 100 times more radiation than nuclear
waste.

At issue is coal's content of uranium and thorium, both radioactive
elements. They occur in such trace amounts in natural, or "whole," coal
that they aren't a problem. But when coal is burned into fly ash,
uranium and thorium are concentrated at up to 10 times their original
levels.

Fly ash uranium sometimes leaches into the soil and water surrounding a
coal plant, affecting cropland and, in turn, food. People living within
a "stack shadow"the area within a half- to one-mile (0.8- to
1.6-kilometer) radius of a coal plant's smokestacksmight then ingest
small amounts of radiation. Fly ash is also disposed of in landfills
and abandoned mines and quarries, posing a potential risk to people
living around those areas.

In a 1978 paper for Science, J. P. McBride at Oak Ridge National
Laboratory (ORNL) and his colleagues looked at the uranium and thorium
content of fly ash from coal-fired power plants in Tennessee and
Alabama. To answer the question of just how harmful leaching could be,
the scientists estimated radiation exposure around the coal plants and
compared it with exposure levels around boiling-water reactor and
pressurized-water nuclear power plants.

The result: estimated radiation doses ingested by people living near the
coal plants were equal to or higher than doses for people living around
the nuclear facilities. At one extreme, the scientists estimated fly ash
radiation in individuals' bones at around 18 millirems (thousandths of a
rem, a unit for measuring doses of ionizing radiation) a year. Doses for
the two nuclear plants, by contrast, ranged from between three and six
millirems for the same period. And when all food was grown in the area,
radiation doses were 50 to 200 percent higher around the coal plants.

McBride and his co-authors estimated that individuals living near
coal-fired installations are exposed to a maximum of 1.9 millirems of
fly ash radiation yearly. To put these numbers in perspective, the
average person encounters 360 millirems of annual "background
radiation" from natural and man-made sources, including substances in
Earth's crust, cosmic rays, residue from nuclear tests and smoke
detectors.

Dana Christensen, associate lab director for energy and engineering at
ORNL, says that health risks from radiation in coal by-products are low.
"Other risks like being hit by lightning," he adds, "are three or four
times greater than radiation-induced health effects from coal plants."
And McBride and his co-authors emphasize that other products of coal
power, like emissions of acid rainproducing sulfur dioxide and
smog-forming nitrous oxide, pose greater health risks than radiation.

The U.S. Geological Survey (USGS) maintains an online database of fly
ashbased uranium content for sites across the U.S. In most areas, the
ash contains less uranium than some common rocks. In Tennessee's
Chattanooga shale, for example, there is more uranium in phosphate rock.

Robert Finkelman, a former USGS coordinator of coal quality who oversaw
research on uranium in fly ash in the 1990s, estimates that for the
average person the by-product accounts for less than 0.1 percent of
total background radiation exposure. According to USGS calculations,
buying a house in a stack shadowin this case within 0.6 mile [one
kilometer] of a coal plantincreases the annual amount of radiation
you're exposed to by a maximum of 5 percent. But that's still less than
the radiation encountered in normal yearly exposure to X-rays.

So why does coal waste appear so radioactive? It's a matter of
comparison: The chances of experiencing adverse health effects from
radiation are slim for both nuclear and coal-fired power plantsthey're
just somewhat higher for the coal ones. "You're talking about one
chance in a billion for nuclear power plants," Christensen says. "And
it's one in 10 million to one in a hundred million for coal plants."

Radiation from uranium in coal might only form a genuine health risk to
miners, Finkelman explains. "It's more of an occupational hazard than a
general environmental hazard," he says. "The miners are surrounded by
rocks and sloshing through ground water that is exuding radon."

Developing countries like India and China continue to unveil new
coal-fired plantsat the rate of one every seven to 10 days in the latter
nation. And the U.S. still draws around half of its electricity from
coal. But coal plants have an additional strike against them: they emit
harmful greenhouse gases.

With the world now focused on addressing climate change, nuclear power
is gaining favor in some circles. China aims to quadruple nuclear
capacity to 40,000 megawatts by 2020, and the U.S. may build as many as
30 new reactors in the next several decades. But, although the risk of
a nuclear core meltdown is very low, the impact of such an event
creates a stigma around the noncarbon power source.

The question boils down to the accumulating impacts of daily incremental
pollution from burning coal or the small risk but catastrophic
consequences of even one nuclear meltdown. "I suspect we'll hear more
about this rivalry," Finkelman says. "More coal will be mined in the
future. And those ignorant of the issues, or those who have a vested
interest in other forms of energy, may be tempted to raise these issues
again."