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| Peter McIntyre |
COLLEGE STATION, Texas -- In the mind of Texas A&M University physicist Peter McIntyre, two of America's most pressing energy challenges — what to do with radiotoxic spent nuclear fuel and dwindling energy resources — can be solved in one scientific swipe. He is developing the technology that is capable of destroying the dangerous waste and, at the same time, potentially providing safe nuclear power for thousands of years into the future.
In his high-energy physics laboratory east of the Texas A&M
campus, McIntyre and his research team are developing a new form of
green nuclear power that would extract 10 times more energy out of spent
nuclear fuel rods than currently obtained in the first use, as well as
destroy the transuranics — the chemical elements beyond uranium in the
periodic table — lurking within the hazardous toxic soup of used nuclear
fuel
Buoyed by seed funding from Texas A&M University ($750,000) and the Cynthia and George Mitchell Foundation ($500,000),
McIntyre is preparing a proposal to the U.S. Department of Energy
seeking the large-scale funding that would enable him to take the next
steps.
Although
viewed as a major national issue, McIntyre says the nuclear waste
problem is a multifaceted one for which no viable solution yet has
emerged, despite decades of discussion. Most recently in 2010, federal
authorities scrapped a plan to create a nuclear waste dump at Yucca
Mountain in Nev., to store the nationwide spent nuclear fuel capacity that now stands at 65,000 tons.
"In
my opinion, the only way to properly deal with transuranics is to
destroy them," McIntyre said. "They are an unthinkable hazard if they
ever get into the biosphere. There has long been discussion that we
could find a site like Yucca Mountain that's so isolated from
groundwater and so stable geologically that we could say with confidence
it will be the same 100,000 years from now as it is today, and that
burying fuel there, closing the door and forgetting it is something we
can responsibly do. I don't buy those arguments."
Each
of the nation's 104 reactors is fueled with about 90 tons of enriched
uranium fuel, packaged in sealed metal tubes called fuel pins. As the
uranium fissions, the byproducts are trapped inside these pins, where
they accumulate and begin to take on neutrons that would otherwise be
driving the continuing fission process. The ongoing build-up, which
includes the heavier transuranic elements, renders the reactor
non-operational after about five years once the fission process stops.
At this point, the pins are replaced with a new set, and the spent fuel
typically is stored in a pool of water at the reactor site.
McIntyre,
a professor since 1980 in the Department of Physics and Astronomy and
the inaugural holder of the Mitchell-Heep Chair in Experimental
High-Energy Physics within the George P. and Cynthia Woods Mitchell
Institute for Fundamental Physics and Astronomy, describes his team's
technology as a "win-win."
"It destroys the bad stuff — the transuranics — and recovers the good stuff — the fuel," he said.
To
destroy the transuranics, McIntyre's team has developed a conceptual
design for accelerator-driven subcritical fission in a molten salt core
(ADSMS). With this technology, the transuranics are extracted into
molten salt using a process called pyroprocessing, in which the spent
fuel pins are chopped up and loaded into a basket, which is placed in a
pot of molten salt. The oxide fuel inside the pins dissolves in the
molten salt so that all of the remaining fuel — along with all of the
transuranics — is extracted into the molten salt. The transuranics could
then be destroyed through subcritical nuclear fission, which is driven
by a beam of energetic protons within the custom-built, high-efficiency
accelerator he envisions.
McIntyre's design builds on work at Argonne National Laboratory and Idaho National Laboratory as well as the PRIDE facility in South Korea
which demonstrated the process for extracting the fuel and separating
the transuranic elements and fission products in molten salt. Scientists
from those teams are collaborating with McIntyre in the new
development.
"In
the same process by which we extract the transuranics from the spent
fuel, we also extract the uranium so it can be re-used as an ongoing
energy resource to provide nuclear energy for the next several thousand
years," McIntyre said.
The
idea isn't new. But earlier proposals for accelerator-driven
subcritical fission faced the problem that there was no known way to
deliver the necessary proton beam power to a core. The ADSMS design uses
a novel invention of McIntyre's called the strong-focusing cyclotron.
In the strong-focusing cyclotron, bunches of protons are accelerated
through superconducting radio-frequency (RF) cavities and focused using
superconducting beam transport channels. These proton bunches are
continually re-focused to contain high-beam current within the
accelerator aperture — an approach that McIntyre says makes it possible
to deliver 10 times more fission-driving beam power than previously
achievable, and to do it with high-energy efficiency.
"We
are preparing a proposal to the DOE to build and put into operation a
first model of this strong-focusing cyclotron," McIntyre said. "It would
be quite an advance in the field of accelerator physics unto itself.
But most particularly, for the first time, it will make it feasible to
drive a subcritical fission core capable of destroying transuranics at
the same rate they are made in a power reactor."
McIntyre
knows the hurdles ahead for his project, including convincing federal
officials to make a major scientific investment during an age of
cutbacks, and proposing a new and better way for nuclear power at a time
when Fukushima is fresh in the public mind. (McIntyre notes that the
Fukushima explosions in 2011 involved spent fuel storage pools, a
problem his technology would eliminate.)
But
the road the 65-year-old scientist treks has a familiarity to it. He
zigzagged the state and nation in the 1980s — also a time of fiscal
restraint — to make the scientific and political cases for another major
project, the Superconducting Super Collider (SSC), which would have
accelerated particles to nearly the speed of light and maintained
American supremacy in high-energy physics. Congress killed the SSC 20
years ago, and the prospect of big discoveries at the frontier of
high-energy physics gravitated to CERN in Switzerland, which celebrated the discovery of the elusive Higgs boson on July 4 last year.
Physicists, including Stephen Hawking,
have lamented the loss to American science represented by the failure
of the SSC, but McIntyre sees a silver lining to that effort: It gave
him invaluable experience at figuring out how to connect science with
the political leaders who could bring it to fruition, skills the grayer
and wiser McIntyre is using now. Back in the 1980s, he ended up making a
presentation about the SSC in the West Wing of the White House to
then-Vice President George H.W. Bush, who subsequently asked for a two-pager to carry to President Ronald Reagan .
"That
moment was the birth of the SSC," McIntyre said. "That's how things can
happen, and that's how they do happen in this world. It takes
persistence and ingenuity in trying to find a way."
To learn more about McIntyre and his research, go to http://people.physics.tamu.edu/mcintyre/.
