|Each DWPF canister is 10 feet tall and 2 feet in diameter, and typically takes a little over a day to fill.
The largest radioactive
waste glassification plant in the world, DWPF converts the
high-level liquid nuclear waste currently stored at the Savannah
River Site (SRS) into a solid glass form suitable for long-term
storage and disposal.
have long considered this glassification process, called “vitrification,”
as the preferred option for immobilizing high-level radioactive
liquids into a more stable, manageable form until a federal
repository is ready. About 36 million gallons of high-level
liquid wastes are now stored in 49 underground carbon-steel
tanks at SRS. This waste has about 425 million curies of radioactivity,
and requires permanent isolation from the environment.
began in late 1983 on the plant, and it was completed at a
capital cost of $1.276 billion and start-up operating costs
totaling $1.2 billion. Changing environmental requirements
and major safety upgrades and process modifications to the
facility, in addition to implementing an enhanced operator
training program and a “waste qualification” test
phase to demonstrate that the glass form meets all environmental
and operational requirements for long-term storage, were required
before system testing began in 1990. That was followed by
cold chemical tests with non-radioactive simulated waste that
were completed in 1993.
Employees perform operations remotely, from outside
completed its waste qualification testing in late 1995, filling
70 canisters with a nonradioactive glass form that met all
environmental and operational requirements. Nonradioactive
chemicals simulated the properties and constituents of the
DWPF began radioactive
operations in March 1996. The projected production to vitrify
all high-level waste currently stored at SRS is approximately
6,000 canisters over the next 20-25 years. Under an accelerated
risk reduction and closure plan, the number of canisters could
be reduced to 5,000 as a result of a program that will complete
high level waste processing years earlier and at much lower
The Saltstone Facility
safely treats and disposes of low-level liquid radioactive
wastes produced and stored at the Savannah River Site.
primarily sodium nitrate (similar to fertilizer), make up
about 93 percent of the 37 million gallons of material in
the radioactive waste storage tanks in the High Level Waste
(HLW) storage tanks at the site. Pretreatment of this HLW
will separate soluble salts from insoluble sludge to generate
about 100-120 million gallons of salt solution. This salt
solution will be treated to remove cesium and strontium. These
two contaminants are sent to the Defense Waste Processing
Facility, where they are combined with the sludge, turned
into glass and poured into canisters.
Removal of the
cesium and strontium converts the majority of the salt solution
to low-activity waste containing less than 0.01 percent of
the total radioactivity now present in the waste. This salt
solution is sent to the Saltstone Facility for immobilization.
|A portion of the Saltstone facilities
In addition to
receiving low-level waste from the tank farms, Saltstone also
receives a similar waste stream from the Effluent Treatment
Facility. This facility processes other waste from the tank
farms as well as from the site's two chemical separation facilities.
the waste is received at Saltstone, the salt solution is mixed
with cement, fly ash and blast furnace slag to form grout.
The grout is then pumped into large concrete vaults divided
into sections (called cells); here, it cures into stable concrete
(called "saltstone"). Each cell is 100 feet long,
100 feet wide and 25 feet tall. Currently two vaults exist
at the facility, one with 12 cells and one with six cells
(each vault is partially full). After filling, the vault will
be capped with clean concrete to isolate it from the environment.
Final closure of the area will consist of covering the vaults
with a clay cap and backfilling with earth.
shows that any waste constituents leached from the saltstone
will remain within Environmental Protection Agency drinking
water standards. Wells near the edge of the disposal site
are used to monitor groundwater to ensure that it meets standards
established by the South Carolina Department of Health and
|Two Saltstone employees run the mixing and transfer
system from the Saltstone control room.
was completed of the Saltstone Facility and the first two
vaults between February 1986 and July 1988 at a cost of $45
million. The Saltstone Facility started radioactive operations
June 12, 1990, and to date has processed approximately 3.1
million gallons of low-activity waste. The facility was recently
modified to process higher curie levels of material, and is
now waiting permission from DHEC to start up.
RETURN TO TOP