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Dr. Donggao Zhao
Nuclear Waste Management
I worked on two DOE-funded projects (Prof. Rod C. Ewing) related to nuclear waste
management. One project is radionuclide immobilization in the phases formed by corrosion
of spent nuclear fuel. The UO2 in spent nuclear fuel is not stable under
oxidizing conditions. Under oxic conditions, the U(IV) has a strong tendency to exist as
U(VI) in the uranyl molecule, UO22+. The uranyl ions react with a
wide variety of inorganic and organic anions to form complexes that are often highly
soluble. The result is rather rapid dissolution of UO2 and the formation of a
wide variety of uranyl oxide hydrates, uranyl silicates and uranyl phosphates. The
reaction rates for this transformation are rapid, essentially instantaneous on geologic
time scales. Previous investigations have established that natural uraninites and their
alteration products can be used as natural analogues to study the corrosion of UO2
in spent nuclear fuel. A paper on the long-term corrosion products of natural uraninite UO2+x
under oxidizing conditions and the fate of the trace elements has been submitted.
A second project of nuclear waste management is borosilicate glass as a waste form for the
disposal of high-level nuclear waste. The objective of my research effort is to understand
the distributions and solubilities of radionuclides and neutron absorbers in glass waste
forms. The results will provide the knowledge for developing, evaluating, selecting, and
matching waste forms for the safe disposal of various wastes associated with Pu,
miscellaneous spent nuclear fuels (SNF), and other transuranic (TRU) wastes and for
developing deterministic model for the long-term performance assessment of radionuclide
containment. One manuscript from this project has also been submitted for publication.
Useful Links
donggao_zhao@yahoo.com |
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