http://www.cnn.com/2001/TECH/science/04/06/radioactive.tumbleweeds.ap/index.ht
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Latest nuclear menace: radioactive tumbleweeds
RICHLAND, Washington (AP) -- The Cold War may be over, but Hanford nuclear
reservation continues to battle Russian invaders: radioactive tumbleweeds.
Russian thistle is a dead menace here on the windswept desert of
south-central Washington. Each winter, the deep tap root on the plant decays,
and the spiny brown skeleton above ground breaks off and rolls away.
"Our dream is that we have this place tumbleweed-free," says Ray Johnson, a
biological control manager for radiation protection at Fluor Hanford, the
contractor managing the U.S. Department of Energy site.
But that's about as likely as a Soviet reunion.
While less than 1 percent of the tumbleweeds corralled and compacted at
Hanford are radioactive, the cost of cleanup can run into millions of
dollars.
Hanford is the most contaminated nuclear site in the country, built in 1943
for the top-secret Manhattan Project. For 40 years, Hanford made plutonium
for the nation's nuclear arsenal, including the atomic bomb that was dropped
on Nagasaki, Japan. The last reactor was shut down in 1986.
Russian thistle, a nonnative or invader species, is a particular problem at
underground burial sites for radioactive waste, where their tap roots reach
down as far as 20 feet (6 meters) and suck up such nasty elements as
strontium and cesium.
A stiff winter wind can push the tumbleweed as far away as four miles, and
then "we've lost control of our contamination," Johnson says. But most get
hung up within a few hundred yards, usually on sagebrush, fences or in
stairwells at the buildings scattered across the site.
Two years ago, uncontrolled contamination spread by fruit flies made Hanford
a national laughingstock, spoofed by humor columnist Dave Barry and in the
syndicated comic strip "Sylvia."
The flies had been attracted to a soil fixative with saccharin in the base
that was being sprayed on a contaminated site. They flew to a lunch room, and
spread the taint to nearby trash bins, which wound up at the Richland
municipal landfill.
Johnson can chuckle about it now, recalling attempts to find the source of
the contamination. As crews ran radiation detectors around the lunch room and
passed over a fruit fly, "the contamination flew away," he recalls.
The journeys of a few thousand fruit flies cost $2.5 million to clean up.
Riding herd on Hanford's tumbleweeds, and its flying insects, is part of an
annual $4 million integrated soil, vegetation and animal control (ISVAC)
program, run by subcontractor DynCorp. for Fluor Hanford.
Radiation control specialists survey the tumbleweeds on the 560-square-mile
(1,450-square-kilometer) reservation, using Geiger-Mueller counters that
click when radioactivity is present. If contaminated tumbleweeds are found,
an ISVAC crew disposes of them.
"The weeds are fairly low danger," says Todd Ponczoch, a radiation control
technician, using a Geiger counter to scan tumbleweeds along a fenceline.
None registered radioactive on a recent trip.
A large, three-pound (1.3-kilogram) radioactive tumbleweed might measure out
at 150 millirads, or about 1/100th of the allowable annual dose of radiation
per person at Hanford.
Radioactive tumbleweeds are pitchforked by specially trained and clothed
workers into a regulated garbage truck, compacted and disposed of at an
on-site low-level waste dump. A trail of paperwork is required as well.
The sites must be satisfactorily cleaned up and covered with six inches of
clean soil or gravel.
Nonradioactive tumbleweeds are territory for the Teamsters.
"It's an easy job. It gets us outside," says Joe Aldridge, a Teamster from
Richland, as he pitchforks a plant into the garbage truck which can hold
about 1,800 pounds (810 kilograms) of tumbleweeds.
The uncontaminated tumbleweeds are dumped in an open pit. Up until five or
six years ago, the "clean" tumbleweeds were burned and the ash buried. But
the state Department of Health put a halt to that practice for fear that some
radioactive tumbleweeds might find their way into the mix and disperse
contamination into the air.
Preventive measures are also part of the control program, and include
backpack, roadside and aerial spraying with herbicide to kill the thistle.
Sometimes a bio-barrier -- a costly engineered textile -- is laid down to
block the formation of thistle roots.
"What you've got to do is make sure your contaminated areas are
tumbleweed-free," Johnson says.
Clearly, this isn't Kansas, where at least two enterprising souls are raising
Russian thistles, turning them into tumbleweeds and selling them for home
decor. But in the vast, open and uncontaminated portions of the reservation,
some areas are simply left to nature.
Even Johnson can acknowledge their rightful place in the world.
"If we didn't have them, the West wouldn't be the West," he says, "and we
couldn't sing 'Tumblin' Tumbleweeds."'
