What Do You Do With the World's Most Dangerous Trash?
In
the last 50 years the United States has produced approximately
30 million tons of high-level radioactive waste, mostly spent
fuel from nuclear power reactors and radioactive debris from weapons
production. The material, which will remain hazardous for more
than two million years, has been temporarily stored at more than
100 sites across the nation. After 20 years of study, the federal
government recommended in 2002 that Yucca Mountain, a remote site
in the Nevada desert 100 miles northwest of Las Vegas, become
the permanent repository for this dangerous waste. While critics
question the project's safety, proponents counter that the alternatives
may be even more dangerous. Professor Peter Burns, chairman of
Notre Dame's department of civil engineering and geological sciences,
has been involved in the Yucca Mountain Project for eight years.
Recently, we talked with him about his work and the safety of
Yucca Mountain.
Notre Dame Magazine: Why do you believe Yucca
Mountain would be a safe place to store the nation's high-level
radioactive waste?
Peter Burns: It's very remote, and
it's very dry. If the repository is built, the radioactive waste
would be surrounded by about 1,000 feet of very dense rock and
be 1,000 feet above the water table. It's hard to imagine significant
radiation coming out of that mountain anytime soon.
NDM: You said "if
it is built." Is there a possibility the repository will not be
built?
Burns: There may be some back and forth negotiating
between the Department of Energy and the U.S. Nuclear Regulatory
Commission, but in all likelihood I think the NRC will license
the repository, and it will be built. Right now the Yucca Mountain
Project is preparing to apply to the NRC for a site license this
fall. It will make the case why the DOE scientists believe Yucca
Mountain would be a safe repository. Essentially the process is
one arm of the federal government attempting to prove to another
arm that the project is safe enough to go forward. It may go back
and forth for some time, but, as I said, I think the NRC will
license the repository. Then Yucca Mountain must apply for a construction
license and get the different components of the construction approved.
Only after this rigorous review can they build it and start putting
the waste inside.
NDM: What's your role in all of this?
Burns: Our work is aimed at understanding
how spent nuclear fuel will behave chemically under the environmental
conditions of the repository. It's important to know because at
some point in the future it's certain the canisters containing
the radioactive waste will fail. It's not a matter of "if" but
"when." And when that happens, which hopefully will be in the
far distant future, the canisters will release the material inside
the mountain where it will oxidize and chemically break down.
The mountain then becomes the last barrier between the nuclear
waste and the environment. So it's important to know how this
material will react in that environment. In particular we're concerned
with what happens to the element neptunium.
NDM: Why neptunium?
Burns: Neptunium stays radioactive for a long,
long time. It has a radioactive half-life of 2.14 million years,
and it's very soluble in water. As the radioactive waste chemically
breaks down, we are most concerned how neptunium will be bound
up chemically, and whether these so-called "alteration-phase compounds"
are soluble in water.
There are a lot of ways radiation might be released from the
mountain: A catastrophic volcanic event, human intrusion or a
meteorite impact, for example. But these are all deemed to be
extremely low probability. On the other hand, everyone agrees
that at some point some level of radiation release through groundwater
is a 100 percent certainty. It's only a matter of time and whether
that time frame is long enough for most of the radioactivity to
have decayed away. So our work is aimed at understanding how the
repository will perform in a 10,000- to 100,000-year time frame.
NDM: What have you learned so far?
Burns: It appears that the normal sequence of
chemistry events will significantly retard the release of neptunium
by binding it up in insoluble compounds. Based on what we have
been arguing, the Yucca Mountain Project has reduced the predicted
radiation release rate by a factor of about one million, which
is quite substantial.
NDM: Is there any urgency to the Yucca Mountain
Project?
Burns: The current situation in which the nation's
high-level radioactive waste is being temporarily stored at over
100 sites is flirting with disaster. There's no question that
Yucca Mountain is needed. In fact, we should be working on Yucca
Mountain II. The repository was designed to hold 70,000 tons of
waste. At current rates it will be full by 2010. That's kind of
worrisome.
(July 2005)
