FROM a 19-kiloliter tanker truckload
of wash water to a test-tube-size container of an unusual blend
of noxious chemicals, Lawrence Livermores new Decontamination
and Waste Treatment Facility (DWTF) will take it all, fulfilling
its role of helping the Laboratory keep clean when it
comes to waste.
DWTF is a new, integrated facility for storing and processing the
Laboratorys wastes, whether they be hazardous, low-level radioactive,
transuranic radioactive, or mixed (that is, both chemically hazardous
and radioactive). More than 20 years in the making, DWTF is scheduled
to open by the end of September 2003. According to Stephanie Goodwin,
division leader for Radiological and Hazardous Waste Management,
DWTF will provide safe, cost-effective waste operations and will
broaden Livermores overall internal waste management capabilities.
Our role is to develop and improve ways of managing wastes
generated at the Laboratory to ensure that the environmental impact
of by-products is as negligible as possible, she says. To
that end, we first investigate and then design, develop, and acquire
new, more efficient ways to handle, stabilize, treat, certify, and
dispose of waste. DWTF is key to all those efforts.
of the systems in the Decontamination and Waste Treatment Facility
are computer controlled, including the off-gas system, the
evaporator, and the tank farm. Here, engineer John Fitzpatrick
is shown by the portable operating interface for the liquid
waste processing area. In the background at left is the tank
farm’s central control panel, which shows the conditions
of all tanks—how full they are, their temperature, pH,
conductivity, and oxidation and reduction potential—and
the status of pumps and valves. Every 20 milliseconds, the
computer program reads all inputs and outputs and updates the
color coding on the panel, providing real-time feedback on
Facility Does It All
a commercial industry that turns out widgets and produces the same
kinds of waste streams in basically the same quantities
day after day, Lawrence Livermores unusual and diverse research
and development activities generate comparatively small quantities
of waste of widely varying composition. Waste Treatment group leader
John Bowers explains, For example, we get sink drainings,
water cuttings, wax that has been stripped off floors of buildings
where radioactive materials are used, and contaminated water from
the Contained Firing Facility at Site 300 [Livermores high-explosives
research facility]. Those waste streams and others can contain
alpha, beta, and gamma particles and emitters, as well as organic
constituents such as oils and solvents, and even heavy and transition
metals. It can be a real diverse brew, he concludes.
Weve got to be ready to deal with all of these waste
streams in ways that protect human health and environment and comply
with standards, orders, and regulations. DWTF was designed from
the start to do this very job.
new facility is actually a complex of buildings that includes new
indoor storage areas and a California-permitted treatment plantall
connected to an impressive ventilation system. For treating wastes,
theres a 2,200-square-meter building for processing solid
waste while liquid waste is processed in a 1,600-square-meter building.
An important goal in processing is to reduce the volume of
waste, says chemical engineer Dave Larsen. Since most
waste disposal sites charge by volume, not mass, we do everything
we can to compact and reduce waste volume, both solid and liquid.
So liquid wastes are evaporatedresulting in water, suitable
for sending down a sewer, and a much-reduced solidified secondary
waste. Solid wastes generated at Livermore are shredded to further
squeeze down their volume.
The solid-waste processing building is equipped with two 4.5-metric-ton
bridge cranes that can move large items, drum crushers that can
mash drums of all sizes into flat pancakes, and a transuranic waste
repackaging glovebox that can be used to open, repackage, segregate,
and ready for disposal the contents of 55-gallon (200-liter) waste
centerpiece of the liquid waste processing building is an enormous
enclosed tank farm with nine 17-kiloliter, closed-top
tanks, an arrangement that offers many advantages over the previous
open-air tank farm, which has six open-top 5.5-kiloliter treatment
tanks and four 17-kiloliter storage tanks. Reagents are delivered
directly into the new tank farm using an integrated system.
advantages of the new system are that the tanks are larger and
off gases generated during treatment can themselves be treated,
an option that wasnt available in the old facility. Additionally,
DWTF offers greater control through an enhanced programmable logic
control system. More monitoring is available through augmented sensors,
and waste streams are more segregated through the additional tanks
and isolation plumbing. DWTFs liquid-processing building
includes a process development laboratory that can be used for
studies, process verification, and small-scale treatment. The building
also includes gloveboxes, fume hoods, and a high-ventilation room
to process reactive and highly toxic materials.
solid- and liquid-processing buildings share a ventilation system
designed to control the direction of air flow throughout the facility. With all doors closed and the facility ventilation system
functioning normally, says Larsen, there is a difference
of 0.03 in water-gauge pressure between zones. When the roll-up
doors are opened to let a truck into the truck bay, for instance,
the pressure differential falls dramatically, but the air flow
is still into the building, not out.
the air in the two buildings is fed through enormous banks of high-efficiency
particulate air (HEPA) filtersover 90 of thembefore
it goes out the stacks. We monitor what goes out the stacks
and make sure it meets all standards, notes Bowers. Even the
choppers and shredders have their own HEPA filters. Air is filtered
first at the stations before being sucked into the buildings
ventilation system and filtered again at the main HEPA filter banks.
A similar process occurs in the tank farm, where the gases and
that accumulate in the tanks are routed to a special process off-gas
system that scrubs the gas and uses carbon adsorption to eliminate
acid gas and organic vapor. The end result of having an integrated
ventilation system and operations performed in enclosed spaces
that the public, the workers, and the environment are all protected.
Glossary of Radiological
and Hazardous Waste
waste: Waste that can pose a substantial or potential
hazard to human health or the environment when improperly
managed. It possesses at least one of four characteristicsignitability,
corrosivity, reactivity, or toxicityor appears
on special Environmental Protection Agency lists.
waste: Radioactive waste that results
from the reprocessing of spent fuel elements
from nuclear reactors. It also includes
reprocessed military wastes, such as
waste: A general term for a wide
range of wastes having low levels of
radioactivity. Low-level waste is radioactively
contaminated industrial or research waste
such as paper, rags, plastic bags, protective
clothing, cardboard, packaging material,
organic fluids, and water-treatment residues.
Low-level wastes containing source, special
nuclear, or by-product material are acceptable
for disposal in a land disposal facility.
waste: This waste contains a hazardous waste
component and a radioactive material component. Examples
include liquid scintillation cocktails; corrosive
organics; waste oils; and cleaning, degreasing, and
miscellaneous solvents, which are also radioactive.
waste: Transuranic refers to atoms
of synthetic elements that are heavier
(higher in atomic number) than uranium.
Transuranic waste materials have been
generated in the U.S. since the 1940s,
mostly from nuclear weapons production
facilities for defense programs. The
most prominent element in most transuranic
waste is plutonium. Some transuranic
waste consists of items such as rags,
tools, and laboratory equipment contaminated
with radioactive materials. Other forms
of transuranic waste include organic
and inorganic residues or even entire
enclosed contaminated cases in which
radioactive materials were handled.
Dealing with the Unusual
DWTF uses conventional, tried-and-true techniques and technologies
such as evaporation to treat wastes as simply as possible, whenever
Yet, with the Laboratory being what it is, DWTF and its people need
to be ready to take care of waste streams that, as environmental
engineer Dianne Gates-Anderson explains, are unique and unusual
and require individual attention and specialized treatment. Such
as those aforementioned HEPA filters. HEPA filters are designed
to remove at least 99.97 percent of airborne particles with diameters
greater than or equal to 0.3 micrometers. Eventually, a HEPA filter
traps so many particles that it no longer can hold any more and
must be replaced. In many cases, these spent HEPA filters are highly
contaminated and must be treated.
says, We generate a lot of spent HEPA filters
at the Laboratory that require treatment before offsite disposal.
The Laboratory has also been storing old legacy HEPA filters, such
as those used in gloveboxes, that are often defined as mixed waste
because they are contaminated with both radioactive and hazardous
mixed-waste filters didnt have a lot of attractive treatment
alternativesuntil Gates-Anderson and a team of waste treatment
engineers and technicians developed the patented In Situ Stabilization
and Filter Encapsulation (IS*SAFE) process. This process uses a
commercially available resin that has a waterlike consistency for
3 hours before it turns solid. A vacuum pump sucks the watery resin
into the spent filter, and the resin fills the interior of the
sealing contaminants in place. Once the resin hardens, the contaminants
cannot be removed. The resulting encapsulated HEPA filter, if originally
classified as a mixed waste, is now considered low-level waste
can be disposed of in a regulated waste disposal site. This reclassification
is significant because low-level waste disposal costs are approximately
10 times cheaper than mixed-waste disposal costs.
Decontamination and Waste Treatment Facility’s (DWTF’s)
process off-gas system does double duty removing acid and organic
gases and vapors from off-gases generated throughout the facility.
In the scrubber (the column to the left) off-gases pass over
a hydroxide solution, which neutralizes any acid vapors and
traps them in the basin at the bottom of the scrubber. The
large tank in the middle holds a pair of carbon adsorption
columns that trap organic vapors. Once the off-gas has been
scrubbed clean, it passes through DWTF’s central ventilation
system and its banks of high-efficiency particulate air filters
for a last scrubbing before exiting through the facility’s
notes that the IS*SAFE process has many advantages over previous
treatments. The most important advantage is that its
safe for workers and easy to use. Workers dont have
to destroy, shred, or dismantle the filter, she points out.
Any time workers handle waste less, worker safety is increased.
Another advantage is that IS*SAFE doesnt generate a secondary
waste stream. Theres no off-gassing, very little heat generated
during curing, and the process can be used on older wood-frame HEPA
filters and newer stainless-steel ones. The IS*SAFE process
shows how a complicated problem can be solved without a complicated
solution, says Gates-Anderson.
example of a simple, innovative solution for problematic waste
streams involves depleted uranium waste. Uranium is a highly
reactive metal that oxidizes (burns) easilysometimes even
igniting spontaneously (a quality defined as pyrophoric). Pyrophoric
depleted-uranium wastes are typically placed in steel drums and
covered with liquid prior to storage. In addition to being radioactive
and reactive, uranium metal is also chemically toxic at high concentrations.
The Laboratory has an inventory of about 11,700 kilograms of pyrophoric
depleted uranium. No disposal facility will accept pyrophoric
depleted uranium, says Gates-Anderson, so our goal was
to find a way to convert this waste to something nonpyrophoric that
would be accepted at a low-level radioactive waste disposal facility.
We cant make uranium disappear, but we can make it safe for
headed a three-year Laboratory Directed Research and Development
project to find a way to make uranium safe for disposal.
Her team developed a three-step process of pretreatment, chemical
dissolution with acid, and stabilization of the dissolution products.
Their research focused on the second stepdissolving the solid
uranium metal, which usually involves using a variety of nasty acids.
Since we have a sizable amount of depleted uranium to deal
with, we didnt want a process that would generate even more
waste that we would have to dispose of in turn, she explains.
team explored the possibilities of using a number of reagents singly
and in combination, including hydrochloric, sulfuric, and
phosphoric acids as well as sodium hypochlorite, sodium hydroxide,
and hydrogen peroxide. They zeroed in on a combination of hydrochloric
and phosphoric acids. The process yields a semisolid uranium (IV)
and phosphate compound, which is nonpyrophoric. All we need
to do at that point is neutralize its pH, solidify the material
using conventional methods, and then we can dispose of the uranium
as a low-level waste, she says.
Gates-Anderson holds a piece of encapsulated high-efficiency
particulate air (HEPA) filter. The IS*Safe process she and
others developed encapsulates contaminants in used HEPA filters
easily, safely, and without generating secondary waste as other
processes do. This is good news for the DOE complex, which
annually generates thousands of used HEPA filters that must
be treated before disposal.
Theres no way around the fact that a by-product of the Laboratorys
national security missions is an unusually diverse variety of wastessome
hazardous, some radioactive, some both. There is no magic wand one
can wave to make this waste disappear or transform. But DWTF offers
a realistic and responsible solution. Goodwin concludes, The
Laboratory has the responsibility to manage its waste from cradle
to grave. The researchers and scientists generate the waste
in their workthe cradleand here in our division we have
to get it in the grave in ways that are safe, appropriate, and meet
all regulatory requirements. DWTF enables the Hazardous Waste Management
Division to better support the Laboratorys programs and missions
and to address community concerns with its environmental safety
and health compliance.
Key Words: Decontamination and Waste Treatment Facility (DWTF);
depleted uranium; hazardous, radioactive, and mixed waste; In Situ
Stabilization and Filter Encapsulation (IS*SAFE).
For further information contact Stephanie Goodwin (925) 422-4750
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