SCIENTIFIC RESEARCH OBJECTIVES
The overall objective of stabilization and isolation of mill tailings and
other uranium mining residues is to minimize exposure of target groups
from radiation and contaminants in the various environmental media. This
can be achieved by creating conditions resulting in low source terms for
both aqueous and gaseous releases, and by designing structures resistant
to the development of emergency conditions.
Long-term stabilization and isolation of mill tailings is an active
R&D area, covering inter alia the development of new techniques for
tailings deposition, the geomechanical and geochemical stabilization of
waste materials, and the design of advanced barriers, both at the bottom
and as cappings. A closely related field, which has seen rapid technological
advances over the past decade, is the restoration/decontamination of contaminated
land, and the rehabilitation of engineered landfills.
It is recognized, however, that the above objectives cannot exclusively
be achieved by engineering design, but must involve also adequate management
and planning procedures. Relevant research topics in principle, therefore,
could include:
Planning and management, e.g.
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assessment of likely and probable environmental impacts;
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identification of processes relevant to the long-term performance;
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design features, which improve long-term performance;
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conceptualization of time-frame for close-out, including cutoff;
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conceptualization of remediation goals and techniques;
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active vs. passive controls, i.e. factors influencing the need for maintenance,
the need for institutional control;
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methodologies for quality control and quality assurance (QA/QC);
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design of cost-effective long-term surveillance and monitoring programmes
for
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environmental performance;
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geotechnical performance.
Technologies, e.g.
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identification of properties relevant to the long-term environmental and
geotechnical performance of tailings and structural materials;
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structural integrity of impoundment, viz.
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design features controlling the long-term stability of engineered structures,
e.g. dams;
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techniques for ex post improvement of isolation, e.g. bottom seals;
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design features controlling erosion resistance;
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in situ/on site techniques for ex post treatment of existing tailings,
e.g. solidification, de-watering, capping;
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techniques for (ex post) improvement of the long-term geotechnical performance
of waste materials, viz. biochemical and geochemical resistance of sealants/additives
with respect to structural degradation;
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techniques for cost-effective characterization of radionuclide inventory,
viz. determination of source term characteristics;
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techniques to minimize long-term contaminant release and to improve geochemical
stability of tailing materials including in situ/on-site techniques for
ex post treatment of existing tailings, i.e. to reduce leacheability and/or
permeability, or to reduce Rn emanation;
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Low maintenance/cost or maintenance-free drainage systems and drainage
treatment systems for removal of radionuclides and other contaminants;
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tools (models) for the assessment/prediction of long-term environmental
and geotechnical performance
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mechanistic models
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systems analyses
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fault tree analyses
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incident sequence analyses;
Institutional, legal and economic aspects, e.g.
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site release criteria and use restriction criteria;
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radiological vs. non-radiological issues (legislative aspects of mixed
contamination);
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funding of and liability for remediation/restoration activities.