R. Chiarizia

Bio: R. Chiarizia is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 18 citations.

Secondary cleanup of truex process solvent

Abstract: Several secondary cleanup procedures have been tested for hydrolytically and radiolytically degraded TRUEX process solvent (0.2 M. n-octyl(phenyl)N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO)-1.2 M tributylphosphate (TBP) in n-dodecane). Sodium carbonate scrub was used as primary cleanup. For the secondary cleanup macroporous anion exchange resins and other solid adsorbents, such as goethite (a-FeOOH), alumina and activated charcoal were used. The effectiveness of a cleanup procedure was established by its capability to restore the original americium(III) distribution ratio from low HNO3 concentration, that is characteristic of pristine process solvent. Further information was obtained from the measurement of up to seven successive AmfJIT) distribution ratios with the regenerated solvent, using the stripping conditions of the TRUEX process. Although all the procedures tested proved to be effective in removing most of the unwanted acidic products from the degraded solvent, the use of a stron...

Actinide partitioning—a review

Abstract: Reagents and methods that have been developed during the past 20 years for hydrometallurgical partitioning of actinides from different types of transuranium (TRU) wastes and dissolved fuels are reviewed. Emphasis is placed on the extraction performance of the fully-optimized reagents rather than on the structural iterations that were undertaken (and in some cases are still being conducted) to identify the optimum species. Particular attention is paid to separation processes that have been demonstrated in batch and counter-current solvent extraction, and batch and column mode extraction chromatography. The salient features of the various techniques and reagents for actinide recycle are compared. Sections of the review focus on neptunium behavior in hydrometallurgy and on characterization of those reagents best suited to the separation of trivalent actinides from fission product lanthanides. Selected flowsheets that have been reported for the separation and recovery of actinides from TRU wastes are presented.

Aqueous Partitioning of Minor Actinides by Different Processes

Abstract: Actinide partitioning is a proposed strategy for effective mitigation of the long-term hazards associated with high-level waste (HLW). Octyl-(phenyl)–N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) and diphenyl–N,N-diisobutyl carbamoyl methyl phosphine oxide (DφCMPO) are amongst the promising extractants extensively studied since the 1980s for actinide partitioning from wastes of different origin. During the last two decades, substituted malonamide extractants such as N,N'-dimethyl-N,N'-dibutyl tetradecyl malonamide (DMDBTDMA) and N,N'-dimethyl-N,N'-dioctyl hexylethoxy malonamide (DMDOHEMA) have emerged as viable green alternatives to phosphine oxides. During the last decade, diglycolamide-based extractants such as N,N,N′,N′-tetraoctyl diglycolamide (TODGA) and N,N,N′,N′-tetra-2-ethylhexyl diglycolamide (TEHDGA) have received considerable attention due to overwhelmingly favourable extraction and stripping efficiencies of minor actinides from different types of transuranium (TRU) wastes. The focus o...

Actinide Separation Science and Technology

Abstract: Both the science and technology of the actinides as we know them today owe much to separation science. Conversely, the field of metal ion separations, solvent extraction, and ion exchange in particular, would not be as important as it is today were it not for the discovery and exploitation of the actinides. Indeed, the synthesis of the actinides and the elucidation of their chemical and physical features required continuous development and improvement of chemical separation techniques. Furthermore, the diverse applications of solvent extraction and ion exchange for metal ion separations as we know them today received significant impetus from Cold War tensions (and the production of metric tons of plutonium) and the development of nuclear power for peaceful uses.

Review Article: The Effects of Radiation Chemistry on Solvent Extraction 3: A Review of Actinide and Lanthanide Extraction

Abstract: The partitioning of the long‐lived α‐emitters and the high‐yield fission products from dissolved used nuclear fuel is a key component of processes envisioned for the safe recycling of used nuclear fuel and the disposition of high‐level waste. These future processes will likely be based on aqueous solvent‐extraction technologies for light‐water reactor fuel and consist of four main components for the sequential separation of uranium, fission products, group trivalent actinides, and lanthanides, and then trivalent actinides from lanthanides. Since the solvent systems will be in contact with highly radioactive solutions, they must be robust toward radiolytic degradation in an irradiated mixed organic/aqueous acidic environment, with the formation of only benign degradation products. Therefore, an understanding of their radiation chemistry is important to the design of a practical system. In the first paper in this series, we reviewed the radiation chemistry of irradiated aqueous nitric acid and the tributyl ...

The Truex Process: A Vital Tool for Disposal of U.S. Defense Nuclear Waste

Abstract: The TRUEX (TRansUranium EXtraction) process is a generic actinide extraction/recovery process for the removal of all actinides from acidic nitrate and chloride nuclear waste solutions. Because of its high efficiency and flexibility and its compatibility with existing process facilities, TRUEX has now become a vital tool for the disposal of certain U. S. defense nuclear waste.