Opinions on Yucca Mountain Vary in Scientific Community
Jul 12 - Las Vegas Review - Journal
A federal appeals court determined Friday that an Environmental Protection
Agency standard for the repository, which required that it safely contain
radioactivity for at least 10,000 years, was inadequate.
One scientist said any attempt to complete the repository should be dropped
and the Department of Energy should start looking for another site to dispose of
the nation's 77,000 tons of spent fuel and highly radioactive waste.
Another said the EPA must either appeal the ruling or establish another
safety standard for containing the waste.
A third scientist said the 10,000-year protection period, adopted in 2001,
might be adequate. However, the EPA, based on the ruling, probably needs to do a
better job of explaining why it selected 10,000 years instead of 200,000 years
or more, when people would be most at risk from radioactive releases.
"What it means is that the site should be removed from consideration
because DOE's own calculations show it can't meet a reasonable safety
standard," said geologist Steve Frishman, a full- time consultant for the
Nevada Nuclear Projects Agency.
Friday's ruling by the U.S. Court of Appeals District of Columbia Circuit
said the EPA failed to follow a 1995 recommendation by National Academy of
Sciences, which held that the safety standard should include the periods of
greatest radioactive risk and not necessarily be limited to 10,000 years.
"The geology of Yucca Mountain is not conducive to isolate waste. This
is what we've been saying for years," he said.
Frishman said if Yucca Mountain's geology could isolate the waste without
relying on metal alloy containers to last for 40,000 years, "then the
compliance period wouldn't matter because the waste would be isolated."
"But in this case, Yucca Mountain's vulnerability is shown by the fact
that the highest risks occur after that 10,000-year period. ... This doesn't
prove there is anything fundamentally wrong with geologic disposal. It shows
there's something wrong with Yucca Mountain," he said.
Kevin Crowley, a geologist who directs the National Academies' Board on
Radioactive Waste Management, noted that the court didn't throw out the whole
standard, but instead vacated one part of it.
"The most significant part of that, in my opinion, is the court didn't
necessarily say you couldn't have a 10,000-year standard but said, 'We didn't
like the way you (EPA) arrived at the 10,000-year standard," said Crowley.
The Nuclear Regulatory Commission must determine the repository can safely
contain radioactivity to license its construction. If the EPA pursues a new
safety standard, the Energy Department's plans to submit a license application
to the NRC in December could be pushed back years.
Said Crowley: "Over the long term, you can't have a license for Yucca
Mountain if you don't have a standard. I don't think this means Yucca Mountain
is dead or you need another site."
Congress asked the National Research Council to develop a technical basis for
Yucca Mountain radiation standards in 1992. Three years later, a 15-member
committee recommended the EPA base the standards on calculated risks of people
dying from exposure to radioactive contaminants that might escape the planned
repository rather than setting limits on the amount of radioactive materials
that could escape.
In June 2001, the EPA finalized a 15-millirem annual dose limit to protect
people from releases from the mountain. A separate standard, 4 millirems, was
set for groundwater used for crops and livestock.
The 15-millirem standard applies to people who might live as close as 11
miles from the repository site. In comparison, a chest X- ray can result in up
to a 10-millirem dose.
People are exposed to about 360 millirems of so-called background radiation
each year from natural sources and fallout, according to the EPA. The
15-millirem dose is considered separate from annual exposure to background
radiation.
John Millett, an EPA spokesman in Washington, D.C., had no immediate comment
Friday on the ruling other than to say, "We're going to review it and
determine what next steps to take as soon as possible."
In recommending that the compliance period cover the time when the greatest
risk from exposure occurs, the National Academies committee noted that it is
possible to estimate how effectively the repository could contain waste for up
to 1 million years.
But in a 1999 letter about the issue to the EPA, Lake Barrett, who was the
Energy Department's acting radioactive waste management chief, said that a
significantly longer period than 10,000 years for assessing compliance would be
unprecedented and unworkable.
Yucca Mountain, 100 miles northwest of Las Vegas, is the only site the Energy
Department has studied extensively for the long- term storage of spent fuel
assemblies from the nation's commercial nuclear power reactors. So far, $8
billion has been spent on the project, and plans have called for spending an
additional $50 billion to license and construct a repository and haul the waste
there in the coming decades.
Energy Department scientists have not spent a lot of time calculating how
waste containers would corrode beyond 10,000 years and how that corrosion would
affect potential releases of radioactivity, said Per Peterson, chairman of the
Nuclear Engineering Department at the University of California, Berkeley.
He said if future generations of Nevadans are living in a world where they
are not sampling groundwater for safety "what does that imply? In some ways
we may be providing a rather high standard of protection."
"Clearly it's an important ruling," Peterson said. "On the
matter of the policy associated with whether or not 10,000 years compliance is
adequate, I think the 10,000-year protection is adequate compared to most of the
things we do."
DEADLY DECAYING WASTE
Of the thousands of radioactive isotopes in spent nuclear fuel, decay rates,
or half-lives, vary greatly. A half-life is the time it takes for half the atoms
of a radioactive substance to distintegrate. Here are some example.
Isotope Half-life (in years)
Neptunium-237 2.2 million
Plutonium-242 376,000
Technetium-99 212,000
Thorium-230 80,000
Plutonium-239 24,000
Radium-236 1,600
SOURCE: Department of Energy
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