Wednesday January 6 4:14 PM ET - AP
Traces of plutonium from a test blast in the Nevada desert migrated
nearly a mile through groundwater, according to a study that
prompted the government to recalculate slightly the risks that
would be posed by an underground nuclear waste storage site.
Scientists said the amount of radioactivity that can move in this
fashion is too small to endanger the public, and the U.S. Energy
Department, in reassessing the risks of the government's proposed
waste site beneath Nevada's Yucca Mountain, agreed.
Until recently, it was commonly believed that significant amounts of
plutonium would not move through groundwater because the
element dissolves at a very low rate and attaches strongly to any
rocks it touches.
But in a study published Wednesday in the journal Nature,
researchers confirmed suspicions that plutonium can hitch a ride
on colloids, or particles of debris suspended in water.
Scientists from Lawrence Livermore National Laboratory in
California and Los Alamos National Laboratory in New Mexico
looked at a 30-year-old nuclear blast that reached below the water
table on the Nevada Test Site, where the United States has
conducted 828 underground nuclear tests between 1956 and 1992.
The site is 70 miles northwest of Las Vegas.
The scientists found minute amounts of plutonium - measurable
only by the most sensitive equipment - in test wells nearly a mile
away from the blast, and concluded that the plutonium had flowed
downstream on colloids.
``We have shown there is a new potential pathway that has been
suggested before, but never definitely shown. The question is what
the maximum amount is that you could move. We don't know that,''
said Annie Kersting, a Lawrence Livermore scientist.
The Energy Department wants to build a nuclear waste repository
at Yucca Mountain, about 90 miles northeast of Las Vegas. The
government has already spent $2.2 billion in 15 years of research
in hopes of entombing 80,000 tons of used reactor fuel that will
remain deadly 300,000 years.
The department took the latest findings into account and concluded
that the seepage wouldn't happen for 10,000 to 100,000 years, and
even then, the escaped radiation would be less than the
background amount.
``They are not rates that would bust any kind of standards. We see
no impact,'' said Abe Van Luik, senior technical advisor for
performance assessment for the Energy Department.
Bruce Honeyman, a professor at the Colorado School of Mines,
said the very nature of colloids - their extremely small size and low
concentrations - assure that they would never move large amounts
of radiation.
``The radioactivity is so low that it probably is not of significance for
adverse human health effects,'' he said. ``Conceptually, you can
think of colloids being like a conveyor belt. The belt is really not
turning very quickly.''
The Energy Department's conclusions did not satisfy Bob Loux,
executive director of the Nevada Agency for Nuclear Projects in the
Nevada governor's office. He said he believes containers holding the
waste will fail much more quickly than the government estimates
and allow unknown quantities of contaminants to escape within 500
years.
---------------
Group Plans To Monitor Waste Cleanup - (IDAHO FALLS) -- The
Snake River Alliance wants to hire outside experts to keep an eye
on the clean up of nuclear waste in eastern Idaho. The watchdog
group hopes to get money from the Energy Department... which is
setting up a fund to pay for independent monitoring of waste
cleanup. The outside experts would watch the radioactive and
hazardous waste cleanup at the Idaho National Engineering and
Environmental Lab.
Sandy Perle
E-Mail: sandyfl@earthlink.net
Personal Website: http://www.geocities.com/capecanaveral/1205
"The object of opening the mind, as of opening
the mouth, is to close it again on something solid"
- G. K. Chesterton -
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