Subject: Record of Decision: Savannah River Site Salt Processing
[Federal Register: October 17, 2001 (Volume 66, Number 201)]
[Notices]
[Page 52752-52756]
>From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17oc01-64]
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DEPARTMENT OF ENERGY
Record of Decision: Savannah River Site Salt Processing
Alternatives
AGENCY: Department of Energy (DOE).
ACTION: Record of Decision.
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SUMMARY: The Savannah River Site Salt Processing Alternatives
Supplemental Environmental Impact Statement (Salt Processing SEIS, DOE/
EIS-0082-S2) considered alternatives for separating the high-activity
fraction from the low-activity fraction of the high-level radioactive
salt waste now stored in underground tanks at the Savannah River Site
(SRS) near Aiken, South Carolina. Based on the analysis in the SEIS and
the results of laboratory scale research and development and
independent reviews, DOE determined that any of the alternatives
evaluated could be implemented with only small and acceptable
environmental impacts. DOE has decided to implement Caustic Side
Solvent Extraction for separation of radioactive cesium from SRS salt
wastes because the solvent extraction process is robust and efficient,
and DOE has experience with similar solvent extraction processes such
as PUREX (Plutonium--Uranium Extraction).
Initial implementation of the Caustic Side Solvent Extraction
technology will consist of designing, constructing, and operating a
facility in S-Area. DOE will evaluate the processing capacity needed
based on high-level waste system requirements (including, but not
limited to, waste removal capabilities, optimization of salt-sludge
blending for Defense Waste Processing Facility operations, and
saltstone system modifications or upgrades), projected throughput, and
conceptual design data. Based on these evaluations, DOE may elect to
build a facility or facilities to carry out the Caustic Side Solvent
Extraction process that could accommodate pilot program and production
objectives, but would not exceed the size or processing capacity
evaluated in the Salt Processing SEIS.
In parallel, DOE will evaluate implementation of any of the other
salt processing alternatives for specific waste portions for which
processing could be accelerated or that could not be processed in the
Caustic Side Solvent Extraction facility. These evaluations and
potential operations would be undertaken to maintain operational
capacity and flexibility in the HLW system, and to meet commitments for
closure of high-level waste tanks.
ADDRESSES: Copies of the Salt Processing SEIS and this Record of
Decision may be obtained by calling a toll free number (800-881-7292),
by sending an e-mail request to nepa@srs.gov or by mailing a request
to: Andrew Grainger, National Environmental Policy Act (NEPA)
Compliance Officer, Savannah River Operations Office, Department of
Energy, Building 742A, Room 185, Aiken, SC 29808. The SRS Salt
Processing Alternatives SEIS (including the 38-page Summary) is
available on the Department of Energy NEPA Web site, tis.eh.doe.gov/
nepa/docs/docs.htm. This Record of Decision also will be available at
the above Web site.
FOR FURTHER INFORMATION CONTACT: Questions concerning the SRS Salt
Processing program can be submitted by
[[Page 52753]]
calling 800-881-7292, mailing them to Mr. Andrew Grainger at the above
address, or sending them electronically to the Savannah River
Operations Office e-mail address, nepa@srs.gov.
For general information on the DOE NEPA process, please contact:
Carol M. Borgstrom, Director, Office of NEPA Policy and Compliance,
U.S. Department of Energy, 1000 Independence Avenue, SW., Washington,
DC 20585, 202-586-4600 or leave a message at 800-472-2756.
SUPPLEMENTARY INFORMATION:
Background
Nuclear materials production operations at the SRS resulted in the
generation of large quantities of high-level radioactive waste (HLW),
which is stored onsite in large underground tanks. SRS HLW was
generated as an acidic solution and was chemically converted to an
alkaline solution for storage. In its alkaline form it consists of two
components, soluble salt and insoluble sludge. Both components contain
highly radioactive residues from nuclear materials production.
Radionuclides found in the sludge component include fission products
(such as strontium-90) and long-lived actinides (such as uranium and
plutonium). Radionuclides found in the soluble salt component include
isotopes of cesium and technetium, as well as some strontium and
actinides. DOE has been operating the Defense Waste Processing Facility
(DWPF) since 1996 to vitrify (convert to glass) the sludge component of
HLW to a stable form suitable for disposal in a geologic repository.
DOE continues to manage the salt component within the HLW tank
system. Dewatering the salt solution by evaporation, a process that
conserves tank space, converts the salt solution to a solid saltcake
and a concentrated salt supernatant. In order to process the salt
component using any action alternative described in the Salt Processing
SEIS, DOE must first convert the saltcake back to salt solution. Solid
saltcake would be dissolved by adding water and combined with salt
supernatant to form a salt solution. The highly radioactive
constituents would be separated from the salt solution and vitrified in
DWPF. The remaining low-activity constituents, consisting mostly of
non-radioactive salts, would be stabilized with grout (a cement-like
mixture) to create a saltstone waste form for disposal at the SRS as
low-level radioactive waste.
DOE evaluated the potential environmental impacts of constructing
and operating DWPF in a 1982 EIS (DOE/EIS-0082). In 1994 DOE published
a SEIS (DOE/EIS-0082-S) evaluating changes in the HLW process proposed
after the 1982 EIS was issued. The Record of Decision (60 FR 18589;
April 12, 1995) announced that DOE would complete the construction and
startup testing of DWPF using the In-Tank Precipitation (ITP) process
to separate the high-activity fraction from the salt solution.
DOE designed the ITP process to be carried out primarily in one of
the underground HLW storage tanks. Under the ITP process an inorganic
sorbent, monosodium titanate, would have removed actinides and
radioactive strontium from the salt solution and an organic reagent,
sodium tetraphenylborate, would have precipitated radioactive cesium
from the salt solution. The ITP process included washing and filtration
steps to separate the resulting solids and residual sludge for
vitrification in DWPF. However, tetraphenylborate is subject to
catalytic and radiolytic decomposition that returns cesium to the salt
solution and generates benzene, which is a toxic, flammable, and
potentially explosive organic substance that must be safely controlled.
The ITP process was designed to accommodate some tetraphenylborate
decomposition and to limit benzene accumulation. To achieve the
objectives of the ITP process, however, the decomposition of
tetraphenylborate must be limited to minimize (1) the amount of
precipitated cesium that is redissolved in the salt solution and (2)
the amount of benzene generated. Startup testing of the ITP facility in
1995 generated benzene in much greater quantities than had been
anticipated based on calculations and laboratory experiments, and ITP
startup operations were suspended in order to develop a better
understanding of the ITP process chemistry.
In August 1996, the Defense Nuclear Facilities Safety Board
(DNFSB), chartered by Congress to independently review operations at
DOE nuclear defense facilities and to make recommendations necessary to
protect public health and safety, recommended that planned large-scale
testing of the ITP process not proceed further until DOE had a better
understanding of how benzene was generated and released during the
precipitation process. In response to the DNFSB recommendation, DOE
initiated an extensive chemistry program to better understand the
process of benzene generation and release. In January 1998, DOE
determined that ITP, as designed, could not meet production goals and
safety requirements, because the separation of radionuclides from HLW
salt solution could not be achieved without excessive tetraphenylborate
decomposition and benzene generation. DOE must therefore select an
alternative technology for HLW salt processing.
Alternative Technology Evaluation
Westinghouse Savannah River Company (WSRC), the SRS operating
contractor, evaluated a list of over 140 potential salt treatment
technologies to replace the ITP process and in October 1998 recommended
four technologies for further consideration: Small Tank
Tetraphenylborate Precipitation (Small Tank), Crystalline
Silicotitanate Ion Exchange (Ion Exchange), Caustic Side Solvent
Extraction (Solvent Extraction), and Direct Disposal in Grout (Direct
Disposal). DOE decided in early 1999 to pursue three of the four
candidate alternatives for replacement of the ITP process, dropping
Solvent Extraction because it was considered technically immature for
the salt waste at that time.
In addition to engineering and research and development efforts,
reviews by the National Academy of Sciences have played an important
role in reviewing DOE's technology selection process. In June 1999 the
Under Secretary of Energy requested that the National Academy of
Sciences--National Research Council provide an independent technical
review of alternatives for processing the HLW salt at the SRS. In
response to the request, the Council appointed a ``Committee on Cesium
Processing Alternatives for High-Level Waste at the Savannah River
Site,'' which conducted a review and provided an interim report in
October 1999 and a final report in August 2000. Based on that report's
recommendation and new research and development results from
independent work at Oak Ridge National Laboratory, DOE restored Solvent
Extraction to the list of potential alternatives. In connection with
the August 2000 report, DOE asked the Council to provide a follow-on
assessment, and the Council appointed a ``Committee on Radionuclide
Separation Processes for High-Level Waste at the Savannah River Site''
in October 2000 to review DOE's evaluation of potential technologies
for separating radionuclides from soluble high-level radioactive waste
at the SRS. This second committee conducted its review and provided an
interim report in March 2001 and a Final Report in June 2001. The
report concluded that Caustic Side Solvent Extraction technology
presents the least technical uncertainties of any of the three cesium
separation alternatives.
[[Page 52754]]
Alternatives Considered
The Salt Processing SEIS describes the environmental impacts of the
four salt processing technology alternatives that were evaluated
through engineering and research and development efforts and
independent technical reviews. The four salt processing technology
alternatives considered in the Salt Processing SEIS were Small Tank,
Ion Exchange, Solvent Extraction, and Direct Disposal. The analysis in
the Salt Processing EIS is based on pre-conceptual engineering designs
of the facilities and emissions estimates generated from knowledge of
chemical processes and engineering controls that would be applied. The
Salt Processing SEIS also analyzed a No Action alternative (i.e., a
continuation of current HLW management activities).
The four salt processing technology alternatives considered in the
Salt Processing SEIS share some common features. Each alternative
includes initial separation of low-concentration soluble radioactive
strontium and actinides (including plutonium) by sorption, followed by
filtration. The essential difference among the alternatives is the
technology for removal of the relatively high concentrations of
radioactive cesium. Except for the Direct Disposal alternative, in
which cesium would not be removed but would remain in the fraction
immobilized as saltstone for disposal at the SRS, the final waste forms
are similar for each of the action alternatives. For these action
alternatives the cesium is extracted from the salt solution and
incorporated into a vitrified waste form for eventual repository
disposal, and the remaining low-activity salt fraction is immobilized
as saltstone for disposal at the SRS.
Solvent Extraction
The Solvent Extraction alternative, identified as the preferred
alternative in the final Salt Processing SEIS, would use a highly
specific organic extractant to separate cesium from the HLW salt
solution. The cesium would be transferred from the aqueous salt
solution into an insoluble organic phase, using a centrifugal contactor
to provide high surface area contact, followed by centrifugal
separation of the two phases. Recovery of the cesium by back extraction
from the organic phase into a secondary aqueous phase would generate a
concentrated cesium solution for vitrification in DWPF.
Small Tank Precipitation
The Small Tank Precipitation alternative would use
tetraphenylborate precipitation, the same chemical reaction as in ITP,
to remove the radioactive cesium from the HLW salt solution. The
process would be conducted as a continuous operation using a small,
temperature-controlled reaction vessel to inhibit tetraphenylborate
decomposition and benzene generation. The vessel and operating
conditions would be designed to minimize benzene emission and
flammability hazards by maintaining an inert gas (i.e., nitrogen)
atmosphere within the reaction vessel. DOE learned from the ITP process
experience that temperature control and maintenance of an inert
atmosphere are important for safe and efficient tetraphenylborate
precipitation.
Ion Exchange
The Ion Exchange alternative would use crystalline silicotitanate
resin in ion exchange columns to separate cesium from the salt
solution. The salt solution would be passed through large stainless
steel ion exchange columns filled with the ion exchange resin to react
the cesium with the resin. Treatment of the solution to separate
strontium and actinides, followed by filtration to remove the solids
and residual sludge, would be necessary prior to separating the cesium
to prevent plugging the ion exchange columns.
The Ion Exchange process would result in the accumulation of as
much as 15 million curies of radioactive cesium on the resin inventory
within the process cell. This radioactive loading would require
stringent shielding and operational controls because of high radiation,
high heat generation, and the generation of hydrogen and other gases.
Direct Disposal in Grout
As indicated earlier in this section, under the Direct Disposal
alternative the HLW salt solution would be disposed of at SRS as
saltstone, without prior separation of radioactive cesium. The
resulting saltstone would have radionuclide concentrations less than
Class C low-level waste (LLW) limits, but would exceed Class A limits,
as defined in U.S. Nuclear Regulatory Commission (NRC) regulations at
10 CFR 61.55. These waste classifications do not apply to DOE-generated
LLW, but DOE used the NRC classification system in the Salt Processing
SEIS to describe differences in waste forms because DOE Manual 435.1-1
establishes a process for making waste-incidental-to-reprocessing
determinations in terms of the NRC classifications. The current
Saltstone Facility permit, which was issued by the South Carolina
Department of Health and Environmental Control (SCDHEC) under its State
wastewater authority, authorizes disposal of wastes with radionuclide
concentrations comparable to Class A LLW. Under the permit, DOE must
notify SCDHEC if the characteristics of wastes in saltsone vaults would
change, as would be the case with the higher level of radioactivity in
the final waste form under the Direct Disposal alternative. Also, if
this alternative were implemented, cesium would not be present in
sufficient concentrations in DWPF canisters to make the canisters
``self-protecting.'' This characteristic would be necessary for DOE to
carry out immobilization of certain plutonium materials, as described
in the Surplus Plutonium Disposition EIS (DOE/EIS-0283) and the
associated Record of Decision (65 FR 1608; January 11, 2000).
No Action
Under the No Action alternative in the near term, DOE would
continue current HLW management activities, including tank space
management, without a process for separating the high-activity from the
low-activity salt fractions. DWPF would vitrify only sludge from the
HLW tanks. Saltcake and salt supernatant would be stored in the HLW
tanks and monitoring activities would continue. DOE would continue to
manage tank space to ensure adequate space to meet safety requirements
and closure commitments. Current tank space management projections
indicate that additional tank space would be needed after 2010 to
support continuing operations under the No Action alternative.
Without a salt processing technology in place, however, current HLW
storage operations could not continue indefinitely. DWPF operations
result in large volumes of waste, mostly water, which is returned to
the HLW tanks. DOE uses evaporators to substantially reduce this
volume, but until a salt processing technology is on-line, DWPF
operation will increase rather than decrease the volume of HLW that
must be stored in the tanks.
Environmentally Preferable Alternative
Ion Exchange is the environmentally preferable alternative. Review
of the data presented in the Salt Processing SEIS shows that the
construction and operation activities to implement the Ion Exchange
alternative would have impacts that are generally small and similar to
the other action alternatives. However, because the Ion Exchange
alternative does not use organic materials that generate organic
[[Page 52755]]
compounds (such as benzene) that must be treated, there are no organic
emissions that must be managed. Organic compounds used in the Solvent
Extraction and Small Tank alternatives result in organic emissions that
must be safely managed. Also, certain accidents involving volatile
organic compounds could not occur with the Ion Exchange alternative.
Ion Exchange would result in the lowest radiological dose to the worker
population and the public, although none of the alternatives would
result in adverse health effects from radiological releases during
construction and normal operation.
The No Action alternative is the least desirable both in the short
term, because of the impacts of construction and operation of new HLW
tanks, and in the long term because of the unacceptably high quantity
of HLW contaminants that could be released to onsite streams.
In the short term the Direct Disposal alternative would in many
cases generate the least effluents of any of the processing
alternatives. However, in the long term Direct Disposal would release
greater quantities of contaminants to the environment than would the
other processing alternatives because of the much greater concentration
of cesium that would be disposed of in saltstone. For this reason
Direct Disposal cannot be considered the environmentally preferable
alternative.
Comments on the Final Supplemental EIS
On July 30, 2001, the Defense Nuclear Facilities Safety Board
(DNFSB) commented on DOE's identification of the Solvent Extraction
alternative as the preferred technology for processing salt waste at
SRS. DNFSB urged DOE to pursue a back-up technology through pilot scale
operations to give DOE more flexibility in addressing unforeseen
technical or programmatic issues. The DNFSB letter identified the Small
Tank Precipitation alternative as an apparently appropriate back-up
technology. The DNFSB letter also stated the belief that DOE would
benefit from further assessment of direct disposal of low-source-term
wastes. In an August 24, 2001, response to the DNFSB letter, DOE
expressed appreciation for the DNFSB's perspective on the technologies
and associated technical challenges, and pledged to continue to work
closely with the DNFSB and its staff to communicate the bases of the
DOE approach as well as progress on assuring that the project proceeds
safely and effectively. DOE will continue laboratory testing of the
other technologies in support of potential future needs as a backup
technology and as potential technologies for processing specific
portions of the HLW until such time as a Solvent Extraction facility is
operational and has proven successful.
By letter dated August 15, 2001, the United States Environmental
Protection Agency, Region 4 (EPA) commented on the Final Salt
Processing SEIS. EPA stated that the disposal routes and locations for
secondary waste streams, including low-level waste that would be
generated from the Small Tank and Solvent Extraction technologies, were
not discussed clearly in the EIS. On June 28, 2001, DOE published an
Amended Record of Decision (66 FR 34431) for the SRS Waste Management
EIS (DOE/EIS-0217, July 1995), announcing DOE's decision to ship
certain SRS low-level and low-level mixed waste streams offsite for
treatment and disposal at commercial or Government facilities. DOE will
select among the disposal options considered in the SRS Waste
Management EIS, depending upon the volume and characteristics of the
salt processing alternative waste stream, and the costs of treatment
and disposal. The Final Salt Processing SEIS acknowledges the
possibility of offsite treatment or disposal for certain waste streams,
but at this time DOE cannot be more specific about which disposal
options would eventually be chosen.
EPA requested clarification on the current viability of the
Consolidated Incineration Facility and other options for treatment of
mixed low-level waste. As is explained on page 1-4 of the Final Salt
Processing SEIS, DOE expects to decide whether to resume CIF operations
by April 2002. DOE is investigating alternatives to incineration and
will not operate the CIF if an effective alternative disposition of
PUREX solvents can be identified.
Decision
DOE has decided to implement Caustic Side Solvent Extraction for
separation of radioactive cesium from SRS salt wastes. The results of
research and development activities were an important factor in DOE's
selection of a salt processing technology. DOE has performed research
on each of the three cesium removal technology alternatives since 1998.
Independent scientists and subject matter experts have reviewed the
results of the research and assessed the advantages and disadvantages
associated with each of the identified alternatives, considering life
cycle costs and schedules for the design, construction, and operation
of each alternative. In addition to, and in consideration of this
research, analysis, and independent review, DOE conducted a final
management review that comparatively evaluated each of the action
alternatives against a list of criteria that included cost, schedule,
technical maturity, implementability, environmental impacts, facility
interfaces, process simplicity, process flexibility, and safety.
Although Solvent Extraction uses a complex four-component solvent
system, laboratory testing has clearly shown that component
concentration and process flow can be maintained to effectively remove
cesium from the wastes. Other key strengths identified for the Solvent
Extraction technology include: (1) Maturity of and experience within
the DOE complex for solvent extraction processing of nuclear material,
(2) simplicity with which the Solvent Extraction product stream could
be incorporated into the current DWPF vitrification process, and (3)
the ability to rapidly start up and shut down the Solvent Extraction
centrifugal contactors, which lends flexibility by allowing
responsiveness to processing contingencies elsewhere in the HLW
management system. DOE believes the Solvent Extraction process to be
robust and efficient. In addition, DOE has extensive experience at the
SRS with a similar solvent extraction process, Plutonium--Uranium
Extraction (PUREX). The PUREX process has been used in F- and H-Canyons
at SRS for almost 50 years to extract plutonium and uranium from
solutions created by the dissolution of nuclear fuel and targets.
In addition to engineering and research and development efforts,
the National Academy of Sciences has played an important role in
evaluating DOE's technology selection process. In June 1999 the Under
Secretary of Energy requested that the National Academy of Sciences--
National Research Council provide an independent technical review of
alternatives for processing the HLW salt at the SRS. In response to the
request, the Council appointed a ``Committee on Cesium Processing
Alternatives for High-Level Waste at the Savannah River Site,'' which
conducted a review and provided an interim report in October 1999 and a
final report in August 2000. Based on that report's recommendation and
new research and development results from independent work at Oak Ridge
National Laboratory, DOE restored Solvent Extraction to the list of
potential alternatives. In connection with the August 2000 report, DOE
asked the Council to provide a follow-on assessment, and the Council
appointed a ``Committee on Radionuclide Separation Processes for
[[Page 52756]]
High-Level Waste at the Savannah River Site'' in October 2000 to review
DOE's evaluation of potential technologies for separating radionuclides
from soluble high-level radioactive waste at the SRS. This second
committee conducted its review and provided an interim report in March
2001 and a Final Report in June 2001. The report concluded that Caustic
Side Solvent Extraction technology presents the least technical
uncertainties of any of the three cesium separation alternatives.
Initial implementation of the Caustic Side Solvent Extraction
technology will consist of designing, constructing, and operating a
facility in S-Area. DOE will evaluate the processing capacity needed
based on the high-level waste system requirements (including, but not
limited to, waste removal capabilities, optimization of salt-sludge
blending for Defense Waste Processing Facility operations, and
Saltstone system modifications or upgrades), projected throughput, and
conceptual design data. Based on these evaluations, DOE may elect to
build a Caustic Side Solvent Extraction process facility or facilities
that could accommodate pilot program and production objectives, but
would not exceed the size or processing capacity evaluated in the Salt
Processing SEIS. In parallel, DOE will evaluate implementation of any
of the other salt processing alternatives for specific waste portions
for which processing could be accelerated or that could not be
processed in the Solvent Extraction facility. These evaluations and
potential operations would be undertaken to maintain operational
capacity and flexibility in the HLW system, and to meet commitments for
closure of high-level waste tanks.
The analysis in the Salt Processing SEIS shows that the
environmental impacts of the construction and operation of a full-scale
Solvent Extraction facility would be generally small and similar to
those of the other processing alternatives. DOE determined that any of
the alternatives evaluated could be implemented with only small and
acceptable environmental impacts. The EIS estimates that the radiation
doses for any of the alternatives would result in a small increase in
latent cancer fatalities in the worker population and the offsite
public, but would be well below applicable standards for both
populations. The Solvent Extraction alternative would generate up to
900,000 gallons per year of radioactive liquid waste. Most of this
volume consists of water that would be evaporated, and the remainder
would be treated at the SRS Effluent Treatment Facility to remove
radioactive substances and discharged as water meeting drinking water
standards. The long term (after mission completion and facility
decommissioning) effect on groundwater quality from residual
radionuclides released from the saltstone vaults would be small and
similar for the cesium separation alternatives, and greater, but still
small, for the Direct Disposal alternative.
Mitigation
DOE is committed to environmental stewardship and to operating the
SRS in compliance with all applicable laws, regulations, DOE Orders,
permits, and compliance agreements. Construction and operation of the
salt processing facility will be conducted in accordance with good
engineering practice that includes measures to minimize the risks
associated with the construction and operation of any industrial
facility. DOE considers these to be standard operating procedures that
do not require a mitigation action plan (under 10 CFR 1021.331(a)).
Issued at Washington, DC, October 9, 2001.
Jessie Hill Roberson,
Assistant Secretary for Environmental Management.
[FR Doc. 01-26082 Filed 10-16-01; 8:45 am]
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