A New Vision for Nuclear Waste
From: Tom Simonds (tsimonds_at_theworld.com)
Date: 12/16/04
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Date: Thu, 16 Dec 2004 08:05:11 -0500
A New Vision for Nuclear Waste
By Matthew L. Wald December 2004
TechnologyReview Magazine (MIT)
When American Airlines Flight 11 flew at low altitude down the Hudson
River valley on the morning of Sept. 11, 2001, its target was the north
tower of the World Trade Center. But its impact is still being felt at a
cluster of buildings it passed about five minutes before it reached
lower Manhattan, at a nuclear-reactor complex called Indian Point in
Buchanan, NY. Adjacent to the site's two operating reactors are two
buildings packed with highly radioactive spent-fuel rods, in pools of
water 12 meters deep and tinged Ty-D-Bol blue by boron added to tamp
down nuclear chain reactions. The soothing hum of the pumps that
circulate the building's warm, moist air-and, critically, keep the water
cool-lends an atmosphere of industrial tranquility.
Without that cooling water, the fuel cladding might overheat, melt,
catch fire, and release radiation. Whether the impact of a Boeing 767
like Flight 11 could drain one of the pools and disable backup water
pumps, starting such a fire, is far from clear. Nevertheless, the threat
of terrorism in general and the flyover of Flight 11 in particular have
reignited the debate about why all of this dangerous fuel is still
here-indeed, why all spent fuel produced at Indian Point in three
decades is still here-and not at Yucca Mountain, the federal government's
burial spot near Las Vegas, where it was supposed to be shipped
beginning six years ago.
Late this past summer, a construction project began at Indian Point that
will allow the fuel to be pulled out of the pools. But it's not going to
Yucca. The government says Yucca won't be ready until 2010. Executives
in the nuclear industry say a more likely date is between 2015 and
never. So instead of traveling to Nevada, Indian Point's fuel is
traveling about 100 meters, to a bluff overlooking the Hudson River. On
a late-summer day this year, a backhoe tore out maple and black-walnut
trees to make way for a concrete pad. Beginning next year, the first of
a planned 72 six-meter-tall concrete-and-steel casks will be placed
there, a configuration that adds storage capacity and thus allows the
twin power plants to keep operating. Though they provide a hedge against
a worst-case fuel-pool meltdown, these casks are merely another
temporary solution. The fact that they're needed at all represents the
colossal failure of the U.S. Department of Energy's Yucca plans and
technology.
Yet as engineering and policy failures go, this one has a silver lining.
Conventional thinking holds that Yucca's problems must be solved quickly
so that nuclear waste can be squirreled away safely and permanently,
deep within a remote mountain. But here's the twist: with nuclear waste,
procrastination may actually pay. The construction of cask fields
presents a chance to rethink the conventional. The passage of several
decades while the waste sits in casks could be immensely helpful. A
century would give the United States time to observe progress on waste
storage in other countries. In the meantime, natural radioactive decay
would make the waste cooler and thus easier to deal with. What's more,
technological advances over the next century might yield better
long-term storage methods. "If it goes on for another 50 years, it doesn't
matter. It could go on for 100 or 200 years, and it's probably for the
better," says Allison Macfarlane, a geologist at MIT and coeditor of a
forthcoming book on Yucca. "We've got plenty of time to play with it."
The government must now accept that its Yucca plan is a failure and that
casks are the de facto solution. Indian Point's cask pad will not be the
first; about two dozen operating reactors have them already. Others are
likely to soon join the list. And some casks-at Rowe, MA, Wiscasset, ME,
Charlevoix, MI, and a site near Sacramento, CA-are nuclear orphans,
having outlived their reactors. Each cask pad is roughly the size of a
football field, floodlit, watched by motion sensors and closed-circuit
TV, and surrounded by razor wire and armed guards. Given the
homeland-security concern posed by nuclear-waste facilities, and the
need to guard them individually, do we really want 60 of them-serving
all 125 commercial reactors that have ever operated-to rise around the
nation, many near population centers? If casks are the solution for the
next generation or two, they should be put in one place.
Yucca is already on tenuous ground; in July a federal appeals court said
that to open the mountain burial site, the government would have to show
that it could contain waste for hundreds of thousands of years.
Extensive scientific analyses by the Energy Department show it cannot.
The court's decision throws the whole question back to the U.S.
Congress, which must now decide whether to proceed with Yucca at all.
This presents an opportunity to align policy with physics and abandon
the Yucca-or-bust dogma that has dominated the debate for nearly 20
years. Casks, centrally located, could make the high-level-waste problem
a lot easier to solve and increase national security much sooner, too.
The Tunnel Vision
The federal fixation on Yucca Mountain now spans two decades. Beginning
in the early 1980s, the government agreed to take waste from any nuclear
utility that paid a tariff of a tenth of a cent per kilowatt-hour
generated by its reactors. All the companies quickly signed up. But the
selection of Yucca, 150 kilometers northwest of Las Vegas, was never
driven by science. The site was chosen by that august group of
geologists and physicists, the U.S. Congress. So far, the Energy
Department has spent about $6 billion on development, including building
an eight-kilometer, U-shaped tunnel through the mountain, in some places
nearly 300 meters below the surface. It plans to spend at least $50
billion more to build dozens of side tunnels, package the waste in steel
containers that look like the tanker portion of a gasoline truck, place
the waste in the tunnels, and operate the site for 50 to 100 years
before sealing it for eternity.
Problems have plagued Yucca since the beginning. In Senate debate,
proponents stressed how dry it is. Yucca is, in fact, located in what is
now a desert. But it turns out that the ground is moist. Even the 19 or
so centimeters of rain the mountain gets each year is a major problem.
Over time, moisture can corrode even the best alloys known to man.
Corrosion would mean that rainwater percolating through the ground could
carry radioactive materials with it and convey them to irrigation
systems and drinking-water wells in the region, delivering substantial
doses of radiation to unsuspecting people generations hence.
Heat is another problem. The shorter-lived radioactive isotopes in used
fuel, principally cesium-137 and strontium-90, give a single fuel
assembly, fresh out of the reactor, a heat output equal to that of about
20 handheld hair dryers. That's why each power plant has an adjacent
storage pool that circulates cooling water. Once the fuel was
underground at Yucca, it would be hot enough to boil ground water into
steam. Steam could corrode the containers or break up surrounding rock,
raising uncertainty about secure burial. Spreading the waste out would
dissipate the heat, but it would also greatly reduce Yucca's storage
capacity. Then there's the problem of radioactive decay. High-energy
particles can interact with surrounding materials, breaking them down or
causing them to give off hydrogen, a gas that can explode or burn.
Early this year, researchers at Catholic University of America, hired by
the state of Nevada, took samples of the kind of metal the Energy
Department wants to use at Yucca and put them in some water mixed with
the minerals present in the mountain. As a series of speakers lectured
reporters on why Yucca was a bad idea, the researchers sautéed the metal
over a burner. By the time the lectures were done, the samples had
corroded, some of them all the way through. How faithfully the stunt
reproduced the chemistry of Yucca Mountain is debatable. But clearly,
Yucca is subject to serious doubts. "You have to think somewhere back in
the premise structure of the whole thing, something was dreadfully
wrong," says Stewart Brand, a San Francisco-based consultant who once
advised the Canadian government on what to do with its own waste.
Cooler Fuel
The argument against casks is that they are merely temporary, not meant
to serve longer than perhaps 100 years, and that they are a kind of
surrender, leaving this generation's waste problem to a future
generation to solve. Yet their impermanence is exactly what's good about
them. A century hence, spent reactor fuel will be cooler and more
amenable to permanent disposal. In fact, within a few decades, the
average fuel bundle's heat output will be down to two or three hair
dryers. After 150 years, only one-thirty-second of the cesium and
strontium will remain. The remaining material can be buried closer
together without boiling underground water. Reduced heat means reduced
uncertainty.
Granted, spent fuel will be far from safe after such a relatively short
period. Even after 100 years, it will still be so radioactive that a few
minutes of direct exposure will be lethal. "It's many, many, many
thousands of years before it's a no nevermind," says Geoffrey Schwartz,
the cask manager for Indian Point, which is owned by Entergy Nuclear.
"But the spent fuel does become more benign as time goes by."
The fuel could be more valuable, too. For decades, industry and
government officials have recognized that "spent" reactor fuel contains
a large amount of unused uranium, as well as another very good reactor
fuel, plutonium, which is produced as a by-product of running the
reactor. Both can be readily extracted, although right now the price of
new uranium is so low, and the cost of extraction so high, that
reprocessing spent fuel is not practical. And the political climate does
not favor a technology that makes potential bomb fuel-plutonium-an item
of international commerce. But things might be different in 100 years.
For starters, the same fuel could be reprocessed much more easily, since
the potentially valuable components will be in a matrix of material that
is not so intensely radioactive.
And in 100 years, advances in reprocessing technology might make the
economics compelling. The existing American technology dates from the
Cold War and involves elaborate chemical steps that create vast
quantities of liquid waste. But an alternative exists:
electrometallurgical reprocessing. Though research into the technique
has lagged of late because of the economic climate, the concept might be
taken more seriously in the future. Electrodes could sort out the
garbage (the atoms formed when uranium is split) from the usable uranium
(the uranium-235 still available for fission and the uranium-238 that
can be turned into plutonium in a reactor), in something like the way
jewelers use electrometallurgy to apply silver plate. Resulting waste
volumes would be far smaller.
Perhaps most importantly, in 100 years, energy supply and demand might
be very different. Reprocessed nuclear fuel might well become a critical
part of the energy supply, if the world has run out of cheap oil and we
decide that burning coal is too damaging to our atmosphere. If that
happens, we might have 1,000 nuclear reactors. On the other hand, we
might have no reactors, depending on the progress of alternate energy
sources like solar and wind. At this point, it's hard to tell, but we
are not required to make the decision now; we can put the spent fuel in
casks for 50 years and then decide if it is wheat or chaff.
There is a final, more practical reason that we might choose to take the
plutonium out of spent fuel for reactor use: it makes the remainder
easier to store. For the most part, what's left will not be radioactive
for nearly as long, and the sheer volume of material will be lower. Mark
Deinert, a physicist at Cornell University, says reprocessing, like
recycling, removes about half of the material from the waste,
dramatically decreasing storage costs and effectively doubling the
capacity of a facility like Yucca.
Betting on Better Storage
While nuclear waste would be easier to handle in 50 or 100 years, it
would still require isolation for several hundred thousand years. But
there is every reason to expect that storage technology will improve in
the next century. When we decide to permanently dispose of the waste,
either after reprocessing or without reprocessing, we may be smarter at
metallurgy, geology, and geochemistry than we are now.
Today, the basic technology at Yucca is a stainless-steel material
called alloy 22, covered with an umbrella of titanium-a "drip shield"
against water percolating down through the tunnel roof. That could look
as primitive in 100 years as the Wright brothers' 1903 Flyer looks to us
in 2004. Or it might simply be obsolete. Space-launch technology could
become as reliable as jet airplanes are today, giving us a nearly
foolproof way to throw waste into solar orbit. The mysteries of
geochemistry might be as transparent as the human genetic code is
becoming, which would mean we could say with confidence what kind of
package would keep the waste encased for the next few hundred thousand
years.
Or there might be easier ways to process the waste. For example,
particle accelerators, routinely used to make medical isotopes, could
provide a means to make the waste more benign. The principle has already
been demonstrated experimentally: firing subatomic particles at
high-level radioactive waste can change long-lived radioactive materials
to short-lived ones. Richard A. Meserve, a former chairman of the U.S.
Nuclear Regulatory Commission and now the chairman of a National Academy
of Sciences panel on nuclear waste, says this technology, known as
transmutation, might become more practical in 100 years. The technology
of accelerators has advanced in the last few years, he says, and it is a
good bet that it will continue to do so.
Some alternative storage technologies may need only a few more years of
research and development. One is ceramic packaging. Ceramics have good
resistance to radiation and heat, and they don't rust. At the moment,
nobody casts ceramics big enough to hold fuel assemblies, which are
typically about four meters long. But there is no theoretical limit to
the sizes of ceramics; there has simply been no economic incentive to
make giant ones. Nor will there be, until the only likely customer for
them, the Energy Department, decides that the metal it is shopping for
now isn't up to the job.
Another alternative calls for mixing waste with ceramics or minerals to
form a rocklike material comprising about 20 percent waste. The waste
would be chemically bound up in stable materials that are not prone to
react with water. With a few decades' grace time, engineers could build
samples and test them in harsh environments. But even though the idea
has been around for more than 10 years, no one has put serious research
money into it, since its only possible American customer, the Energy
Department, has been committed to Yucca.
That situation shows no sign of change. The Energy Department, following
Congress's orders, has so far declined to consider alternatives.
Man-Sung Yim, a nuclear researcher at North Carolina State University in
Raleigh, argues that some of these technologies are already mature but
have been shoved aside in the Energy Department's rush, possibly futile,
to open Yucca. "My reading at this point is, people working at the Yucca
Mountain project office do not really want to change the design. The
more change you bring in, the more delayed the processes," Yim says. "It's
a pity, because we could make it better."
Central Casking
But the pursuit of the perfect solution (assuming deep geologic disposal
even could be perfected) has ignored a realistic solution. And when the
perfect fails, as now seems likely, we will be left with something no
rational person would have chosen: waste sites scattered from coast to
coast, in places where reactors used to be, each with its own security
force, maintenance crew, and exclusion zone. "We're here to run a
business as efficiently as possible," says John Sanchez, the project
manager who oversaw the planning for the pad at Indian Point when he
worked at Consolidated Edison, the site's former owner. "In a perfect
world, you would not have 60 of anything, if you could have one." But
after 20 years of pursuing geologic disposal, and 15 years of chasing
Yucca and avoiding any mention of a plan B, just such an ad hoc, and
suboptimal, solution is emerging.
And it's emerging without the support of the Energy Department.
Testifying before the Senate Energy Committee over the summer, Kyle
McSlarrow, the Energy Department's deputy secretary, said that
"continued progress toward establishing a high-level waste repository at
the Yucca Mountain site is absolutely essential." He told another
committee on the same day that with progress toward Yucca's opening,
"industry saw clearly that the nuclear-power option was truly back on
the table." (The department would not make McSlarrow or other officials
available for comment for this article.)
Cask storage is not pretty, but what's wrong with the idea of an
industrial repository, a few hectares set aside for the next century or
so, a single, guarded location in a little-populated area, a location
that in ten years or so will be remarkable only because it's a place
where the snow doesn't stick? Macfarlane of MIT says making such site
secure and terrorist-proof would cost $6.5 billion, at most. "Isn't that
worth it? How much have we spent on Iraq? Look what we got for that
money. And there's more at risk here," she says.
Finding a central site poses obvious challenges; nobody wants any type
of radioactive waste site in his or her backyard. But after extended
negotiations, a group of utility engineers, including Sanchez, cut a
deal with the Skull Valley band of the Goshute Indian tribe for a long
lease on part of its reservation 80 kilometers west of Salt Lake City.
The area already hosts an air-force bombing range, a nerve gas depot and
incinerator, and a dump for low-level radioactive waste; the Goshutes
figure they can use the rent to buy themselves land in a nicer
neighborhood.
Some experts think the federal government could take over the Goshute
project and push it to completion, but there is a snag-an ironic one,
given the fears of a September 11-style attack on a nuclear site. The
Nuclear Regulatory Commission has determined that an F-16's crashing
into the casks on its way to or from the test site is a "credible
accident." But while such a crash would doubtless be disastrous, casks
do provide some safety advantages over today's fuel pools. The fuel in
casks is much more spread out and does not require a flow of cooling
water to prevent spontaneous, spreading fire. Thus the worst-case
effects are more limited. In any case, one remote central site would be
easier to protect with air defenses than numerous scattered sites.
Those scattered sites are already creating local problems. The casks
from the former reactor in Wiscasset, ME, are blocking the redevelopment
of the peninsula where they're stored, a valuable industrial site. A
cask site near the Prairie Island Nuclear Generating Plant in Welch, MN,
is adjacent to a tribal day-care center and casino, which is nobody's
idea of a long-term solution. Inevitably, in the wake of September 11,
the Indian Point casks will be a locus of fear. These outcomes will seem
even sillier in 30 years, when many of the reactors that made the waste
are gone.
Sanchez recalls carrying a picnic lunch to the stand of maples and
black-walnut trees now being replaced with a concrete pad for storing
nuclear waste. As the years roll by, fewer and fewer people will know
those trees existed. Several decades from now, as today's aging nuclear
power plants are decommissioned, people may not remember that the
reactors themselves existed. If we don't take action soon, however,
casks of waste will stand alone on that bluff above the Hudson River-and
in dozens of other places across the country.
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