Fundamental Understanding of Technetium-Inorganic Solid Interactions: Towards Novel Composites for Selective Removal and Long-Term Storage of Technetium
EMSL Project ID
49719
Abstract
The rising global demand for carbon free energy has placed a considerable burden on renewable energy sources like solar and wind energy in terms of scalability, cost, materials and land use to replace fossil fuels. Nuclear energy has emerged as an attractive option as a source of renewable energy based on the inventory of the total uranium deposits in the world that have the capacity to provide nuclear energy for as long as the relationship between the Earth and Sun is supposed to last (5 billion years).[1] However, consideration of nuclear energy as an integral part of the "green energy mix" requires a significant progress in long-term safe disposal strategies for the generated nuclear waste. One of the key components of this waste is technetium-99 (Tc), a high-yield fission product of uranium-235 and plutonium-239. Tc has been generated in significant quantities by nuclear weapons production since the Cold-War time, and its inventory continues to increase steadily with nuclear power generation. Two of the major Tc-contributors are (a) nuclear tank wastes stored at US Department of Energy sites and (b) used nuclear fuel. The radiotoxicity, long half-life (2.14x105 years), high water solubility and mobility in aquatic ecosystems under oxidizing conditions of Tc makes it a significant environmental concern, motivating significant research thrust directed at its removal, and subsequent safe disposal. While solvent extraction is proposed for separation of Tc from multicomponent spent nuclear fuel within PUREX-like scheme, separation protocols for Tc remediation from multicomponent tank waste supernatants requiring its selective uptake has yet to be determined. Subsequent Tc immobilization into a waste form for storage and disposal is not well established for both sources. To address these needs, we have recently designed layered inorganic composite materials similar in structure to anionic clays, consisting of ordered positively charged sheets intercalated with interchangeable hydrated anions, which have shown promise towards Tc separation from highly alkaline solutions and immobilization. The objective of the proposed work is to address these needs and to gain fundamental understanding of the mechanism and form of incorporation and immobilization of Tc into mineral-like and cementitious matrices. This will lead to the development of new inorganic materials for selective Tc removal from multicomponent matrices typical of tank waste or spent-fuel reprocessing waste followed by its immobilization in the alternative waste forms.
Project Details
Start Date
2017-02-02
End Date
2017-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
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