BUFFALO, N.Y. -- A massive treatment wall under construction
this week at a Western New York nuclear waste cleanup site will
stop radioactive contamination in its tracks for literally decades,
according to University at Buffalo engineers who modeled and tested
the wall's material.
While the treatment method was specifically designed for the
West Valley Demonstration Project, located 30 miles south of
Buffalo, it may eventually be applicable to other radioactive sites
around the nation.
Extending up to 30 feet underground, the 850-foot-long wall is
being constructed with 2,000 metric tons of clinoptilolite, a
volcanic zeolite mineral similar to the material used in cat
litter, horse stalls and waste-disposal.
It is believed to be the first time that this kind of
full-scale, permeable treatment wall is being used to filter out
radioactive material, in this case, strontium-90, which is found in
spent fuel rods in nuclear reactors.
"It functions the way a kitchen water filter does," says Alan
Rabideau, PhD, professor of civil, structural and environmental
engineering in the UB School of Engineering and Applied Sciences,
"only in this case, the filter is selectively removing strontium-90
in the ground.
"As it is held in place, the strontium-90 will decay right in
this huge 'filter,'" he explains. "It removes the strontium-90 and
lets other dissolved minerals go."
According to officials at the West Valley Demonstration Project,
the installation of the treatment wall is an important first step
toward eventually closing the facility.
Back in 1999, Rabideau's research team demonstrated that this
form of clinoptilolite would be suitable for groundwater
remediation at West Valley.
His original, experimental work demonstrated that a
nonradioactive strontium, which behaves like strontium-90, is
captured within the honeycomb structure of the zeolite mineral,
leaving the groundwater essentially free of the contaminant.
For several years, larger-scale testing was deferred while
stakeholders deliberated over plans involving how best to close the
West Valley facility. Then, in 2007, the National Science
Foundation awarded Rabideau and other environmental researchers at
UB funding for an interdisciplinary program they called ERIE
(Ecosystem Restoration through Interdisciplinary Exchange), which
is designed to train a new generation of environmental scientists,
using a nontraditional, interdisciplinary approach.
ERIE student Shannon Seneca, a Western New Yorker and Native
American, was interested in groundwater remediation.
Rabideau and Seneca began conducting more extensive testing
using a "simulated" nonradioactive groundwater in the lab;
eventually, the tests were duplicated using radioactive groundwater
at the West Valley laboratory facility.
With the data they collected from these experiments, which
continued for two years -- an exceptionally long period for such
studies -- they developed complicated mathematical models using
supercomputers at UB's Center for Computational Research.
The goal was to find a way to predict just how long such a wall
could continuously filter out the strontium-90.
The model accounted for the specific groundwater conditions at
the West Valley site, such as the geochemical composition of the
local groundwater, which contains unusually high levels of
chemicals that compete with strontium-90 for storage sites within
the zeolite crystals.
"We now have a computational tool that predicts for how long the
wall will remain effective," says Rabideau. "Our analysis shows
that between 10 and 20 years is the minimum performance that we can
expect at West Valley and some plausible scenarios show the wall
lasting much longer."
Monitoring points placed both within and outside the wall will
provide data for an ongoing performance assessment.
The wall was designed by a team of geologists and engineers led
by UB Department of Geology alumnus Rick Frappa at consulting firm
AMEC-Geomatrix of Amherst, N.Y., in close collaboration with
Rabideau, Seneca and West Valley technical staff. Additional
expertise was provided by Douglas Bablitch and Scott Warner from
the company's headquarters in Oakland, Calif.
Rabideau currently serves on a National Academy of Sciences
panel that is exploring ways to improve hazardous waste management
at thousands of sites where subsurface contaminants create problems
for site closure, potentially threatening public water
While the groundwater plume at West Valley was not in danger of
reaching drinking water sources, the parties involved have long
agreed that the low-level radioactivity in the groundwater plume
must be cleaned up.
In addition to Rabideau and Seneca, Colleen Bronner and Erin
Johnson, both graduate students in the UB Department of Civil,
Structural and Environmental Engineering, also worked on the
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