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Executive Summary
·eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
The United States Department of Energy (DOE) has approximately
400 million liters (100 million gallons) of liquid high-level waste (HLW)
stored in underground tanks and approximately 4,000 cubic meters of
solid HLW stored in bins. The current DOE estimate of the cost of con-
verting these liquid and solid wastes into stable forms for shipment to a
geological repository exceeds $50 billion to be spent over several
decades (DOE, 2000~.
This committees was appointed by the National Research Council
(NRC) to advise the Environmental Management Science Program
(EMSP)2 on a long-term research agenda addressing the above problems
related to HLW3 stored in tanks and bins at DOE sites.4 The complete
statement of task is reproduced in Sidebar P.1 of the Preface.
The committee outlined HLW problem areas that either cannot be
addressed effectively with current technologies, or that are anticipated
for the future. From these problem areas, the committee identified
research objectives, leaving to EMSP investigators the role of determin-
ing the pathway to achieving these objectives through basic research.
Moreover, it is not the purpose of this report to circumscribe the invest)
gators' creativity by giving a detailed list of research projects.
Committee on Long-Term Research Needs for Radioactive High-Level Waste
at Department of Energy Sites.
2The EMSP currently provides the DOE's Office of Environmental Management
with a basic research program to reduce costs, time, and risks associated with
cleaning up the nation's nuclear complex.
3HLW is the highly radioactive waste from the chemical reprocessing of spent
fuel and target materials to recover plutonium and uranium for the production of
nuclear weapons. The committee did not address issues related to spent nuclear
fuel, transuranic waste, in particular plutonium, or other secondary waste streams
from the processing and handling of HLW (see Chapter 1).
4The HLW sites are the Hanford Site, Washington, the Savannah River Site,
South Carolina, the Idaho Engineering and Environmental Laboratory, and the
West Val ley Demonstration Project, New York.
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Throughout the report, examples of research topics are provided to
illustrate how the committee would address the identified HLW prob-
lems. These examples are not to be considered as recommendations or
research priorities.
Long-Term Research Needs
for HEW Management
The recommended long-term research agenda is organized accord-
ing to DOE's current approach to HLW management as follows:
Characterization
Retrieval and pretreatment
· I mmobi I ization
· Tank closure
The motivation for selecting the long-term basic research activities
in this report is to provide contingency approaches for DOE's HLW
management programs and to improve process effectiveness. The com-
mittee recommends research topics that would provide contingency
approaches as the basis for program support in case of interferences or
disruptions to current HLW management plans. Results from these
research activities wou Id help reduce technological risk. The committee
also recommends research topics that wou Id improve process effective-
ness.
The long-term basic research activities are summarized below in
terms of research objectives. More details can be found in the chapters
indicated in parenthesis.
Characterization (Chapter 31: Innovative methods to achieve real-
time and, when practical, in situ characterization data for HLW and
process streams that could be useful for all phases of the waste man-
agement program. The objective of research activities in the area of
characterization is to provide the scientific basis for the following:
· developing remote sensing instruments, and
· developing on-line or in situ instruments.
Pretreatment (Chapter 4~: High-efficiency, high-throughput separa-
tion methods that could reduce HLW program costs over the next sev-
H ~ G H - L E V E E W A S T E
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eral decades. The objective of research activities
ment is to provide the scientific basis for the following:
in the area of pretreat-
· improving sol ids-l iquid separation methods,
· improving underlying science and technology for sludge leach-
ing operations, and
· increasing the efficiency of liquid decontamination methods.
Immobilization (Chapter 51: Robust, high-loading immobilization
methods and materials that could provide enhancements or alterna-
tives to the current immobilization strategy. The objective of research
activities in the area of immobilization is to provide the scientific basis
for the fol lowi ng:
· identifying alternative immobilization media to overcome limita-
tions of borosilicate glasses,
· i nvestigati ng the effect of i ncreased crystal content on the du ra-
bility of the borosilicate glass matrix,
improving phenomenological models to predict long-term leach-
ability of various glass waste forms,
· evaluating advantages of using unreacted glass-forming chemi-
cals compared to premelted glass frit,
· understanding foaming in loule-heated melters,
.
mitigating the effects of precipitation of noble metals and crys-
tal I i ne phases i n You [e-heated melters,
improving Joule-heated melters to achieve higher processing
temperatures, and
· developing alternatives to Joule-heated melting.
Tank closure and other long-term issues (Chapter 61: Innovative
methods to achieve tank closure, non-invasive monitoring of the near-
field areas, as well as improved containment barriers. The objective of
research activities on this topic is to provide the scientific basis for the
fol lowi ng:
· developing highly innovative and effective retrieval methods for
removal of residual HLW materials from tanks,
· developing highly innovative and effective retrieval methods for
removal of HLW materials from connecting pipelines,
· improving the characterization of residual waste in tanks,
developing noninvasive near-field monitoring techniques, and
Improving near-field containment methods through the use of
barriers.
. .
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EMSP Research Portfolio: Technological
Risk and Desired Attributes
The committee provides programmatic recommendations on the
management of technological risk and discusses desired attributes for
the EMSP research portfolio. An analysis of this portfolio, with respect
to HLW research activities, is provided as an interim report, reproduced
i n Append ix A. The mai n fi nd i ngs and recom mendations from Append ix
A are included in the body of this report.
, ,
Managing Technological Risk
The research program proposed by the committee could help the
EMSP in reducing technological risk.5 Technological risk can be
reduced by improving process effectiveness and by providing contin-
gency approaches to baseline technologies before disruptions or inter-
ferences to current HLW processing programs occur. Improving Process
,. .. . . . . . . .. .
a 1
electiveness can lean to more robust approaches that require fewer
steps to achieve the desired result; therefore, a simple and robust
process presents less technological risk compared to a multi-step
process. This is because there is a finite probability of encountering a
problem causing process failure in any one of the individual steps. For
instance, separation techniques removing more than one targeted
species in a single step pose fewer technological risks than a series of
steps to achieve the same result. To provide contingency approaches, it
is necessary to allocate funding for exploratory research relevant to
HLW cleanup. The committee recognizes that exploratory research
efforts do not bear fruit immediately and that results often are not
deployed in the field. However, the success of a basic research program
should not be measured only by the proportion of projects that become
field-appl icable.
Desired Attributes of the EMSP Research Portfolio
In selecting the projects for future HLW proposal cycles, attention to
the following programmatic recommendations is also warranted:
1. Maintain long-term vision. Research projects should be focused
not only on DOE's short-term issues but also on significant long-
5A technological risk in HLW management is the risk that existing technologies
will fail to accomplish goals and performance requirements set by environmental
remediation policies or regulations.
H ~ G H - L E V E E VV A 5 T E
~ A ~
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term problems to advance the state of knowledge well beyond
the next decade. This approach maintains the EMSP long-term
mission and mitigates the technological risk that would interrupt
the Office of Environmental Management (EM) HLW program.
2. Maintain relevance. The EMSP should support basic research on
processes and phenomena that support the EM program mission.
These projects can then feed into other EM programs and spark
the applied research and development that will be needed for
implementation at the sites. Synergies between the EMSP and
other research programs are natural and should be exploited to
their fullest extent. Collaborations with foreign countries with
relevant HLW research activities should be encouraged. At a
minimum, the EMSP should be aware of scientific results and
research trends for HLW management in countries with similar
problems.
3. Provide for contingencies. The EMSP should promote underlying
science and technology that will support contingency approach-
es to address unanticipated difficulties encountered in baseline
processes. Some fraction of EMSP projects should support
exploratory and innovative research involving non-conventional
technologies, possibly leveraged from other disciplines. The pro-
jects should represent a balanced range of research styles, from
large-scale teams to single investigators.
4. Develop working relationships. EMSP i Investigators shou Id i nter-
act with problem holders at the sites to learn about the nature of
the problems to be solved. In return, problem holders might gain
a better understanding of the scientific gaps underlying HLW
problems. EMSP researchers could visit DOE sites regularly to
learn more about specific issues. Conversely, EMSP could identi-
fy "liaisons" among the problem holders at the sites to communi-
cate with its investigators. The liaisons will not only have the
greatest knowledge about the sites but will also be able to assist
i n i ntegrati ng the resu Its of EMSP research i nto the long-term EM
effort.
5. Prioritize objectives. The EMSP should prioritize the two research
objectives of providing contingency approaches and improving
process effectiveness, as follows. The EMSP should strive for a
balanced portfolio addressing both already identified problems
and future potential problems. The portfolio should have a pri-
mary focus on identified problems that must be solved either for
efficient HLW processing operations or to provide for contingen-
cies. Characterization, separation, immobilization methods and
processes are problem areas where EMSP research could
improve operations and provide immediate support in case of
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interferences or disruptions to current HLW processing programs.
At the same time, there should also be a consideration of poten-
tial problems that could arise or become exacerbated in the
future. Examples of recommended research to address future
potential problems are the following: new or better separation
techniques to remove bulk non-hazardous material from the
HLW stream, methods to achieve higher waste loading in immo-
bilized waste forms, and improvements in tank closure and near-
field monitoring issues.
The committee recognizes that the EMSP cannot address all of the
recommended research areas equally in the next few years, nor can its
portfolio acquire all the recommended program attributes immediately.
The committee is also aware of DOE's commitments and of the difficul-
ties in implementing changes, both from a technology and regulatory
point of view. However, current plans to treat and dispose of HLW are
fraught with technical uncertainties, and many of the planned treatment
activities are first-of-a-kind efforts presenting enormous technical chal-
lenges. Given the long-term duration of this planned clean-up effort, it
is expected that new technologies will emerge and that greater scientif-
ic understanding wil I be achieved in the next decades. Therefore, the
EMSP is the ideal setting to develop truly innovative approaches for the
management of HLW that could lead to scientific breakthroughs in the
future. If a scientific breakthrough can help reduce risks, cleanup time,
and costs, then regulations can be revised accordingly and obstacles to
implementing changes at the sites can be removed. In this respect, the
EMSP is a "small but vital element" to the long-term success of the EM
. . .
cleanup mission.
H ~ G H - L E V E E W A S T E
Representative terms from entire chapter:
contingency approaches
