Gary H. Thompson

Bio: Gary H. Thompson is an academic researcher from Rockwell International. The author has contributed to research in topics: Tributyl phosphate & Nuclear reprocessing. The author has an hindex of 1, co-authored 1 publications receiving 18 citations.

Removal of actinides from selected nuclear fuel reprocessing wastes

Abstract: The US Department of Energy awarded Oak Ridge National Laboratory a program to develop a cost-risk-benefit analysis of partitioning long-lived nuclides from waste and transmuting them to shorter lived or stable nuclides. Two subtasks of this program were investigated at Rocky Flats. In the first subtask, methods for solubilizing actinides in incinerator ash were tested. Two methods appear to be preferable: reaction with ceric ion in nitric acid or carbonate-nitrate fusion. The ceric-nitric acid system solubilizes 95% of the actinides in ash; this can be increased by 2 to 4% by pretreating ash with sodium hydroxide to solubilize silica. The carbonate-nitrate fusion method solubilizes greater than or equal to 98% of the actinides, but requires sodium hydroxide pretreatment. Two additional disadvantages are that it is a high-temperature process, and that it generates a lot of salt waste. The second subtask comprises removing actinides from salt wastes likely to be produced during reactor fuel fabrication and reprocessing. A preliminary feasibility study of solvent extraction methods has been completed. The use of a two-step solvent extraction system - tributyl phosphate (TBP) followed by extraction with a bidentate organophosphorous extractant (DHDECMP) - appears to be the most efficient for removing actinides from saltmore » waste. The TBP step would remove most of the plutonium and > 99.99% of the uranium. The second step using DHDECMP would remove > 99.91% of the americium and the remaining plutonium (> 99.98%) and other actinides from the acidified salt waste. 8 figures, 11 tables.« less

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.

Americium recovery and purification using a combined anion exchange‐extraction chromatography process

Abstract: A combined anion exchange-extraction chromatography process for the recovery and purification of americium from molten salt extraction residues has been successfully demonstrated on a laboratory and pilot plant scale. The extraction chromatography process uses dihexyl- N , N -diethylcarbamoylmethylenephosphonate sorbed on Amberlite ® XAD-4 resin. The process effectively separates and purifies americium from impurities such as aluminum, calcium, chloride, copper, fluoride, iron, lead, magnesium, plutonium, potassium, sodium and zinc. A total of 100 g of americium oxide was produced during pilot plant testing. The product oxide contained 96.5 wt.% AmO 2 , with 0.085 wt.% Pu and less than 0.15 wt.% of any other individual impurity element.

Development of highly selective compounds for solvent extraction processes: partitioning and transmutation of long-lived radionuclides from spent nuclear fuels

Abstract: This chapter discusses the methodology deployed in the European partitioning strategy to design highly selective extractants for long-lived radionuclide separation: calix[4]arenes for caesium, malonamides for the co-extraction of trivalent minor actinides (Am, Cm) and lanthanides (Ln(III)), and nitrogen-donor ligands, such as bis-triazinyl-pyridines, for the separation of trivalent minor actinides from Ln(III)