Diglycolamide Complexing Agents for Uranium Decontamination
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Solution Overview
Problem
Current methods for processing spent nuclear fuels, such as the PUREX and COEX™ methods, require multiple purification cycles, including a second uranium cycle, which increases costs and complexity, and the use of lacunary heteropolyanions complicates effluent handling.
Innovation Solution
The introduction of diglycolamides as complexing agents in the first purification cycle allows for the selective transfer of actinides from an organic phase to an aqueous phase, enabling the suppression of the second uranium cycle without adding further handling constraints, using diglycolamides like TEDGA that strongly complex actinides over uranium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple purification cycles (including second uranium cycle) are used in PUREX method, then decontamination of uranium from actinides is improved, but process complexity and costs increase
Solution Approach 1:
The patent applies preliminary action by introducing diglycolamide complexing agents into the first purification cycle to pre-complex actinides before the main uranium extraction. This preliminary complexation of actinides with diglycolamides in the aqueous phase prevents them from being extracted with uranium, thereby achieving decontamination without requiring subsequent additional purification cycles.
Solution Approach 2:
The patent utilizes parameter changes by modifying the chemical environment in the first purification cycle through the addition of diglycolamide complexing agents. This changes the selectivity parameters of the extraction process, allowing actinides to be retained in the aqueous phase while uranium is extracted into the organic phase, thus achieving decontamination within the standard PUREX cycle structure.
2Manufacturing precision
If lacunary heteropolyanions are used for decontaminating uranium from actinides, then decontamination is improved, but effluent handling complexity increases
Solution Approach 1:
The patent employs diglycolamide complexing agents that are simpler, more manageable substances compared to lacunary heteropolyanions. These diglycolamides provide effective actinide complexation without the effluent handling complexities associated with heteropolyanions, offering a more practical solution for industrial implementation.
Solution Approach 2:
The patent uses diglycolamide complexing agents as intermediary substances that facilitate actinide retention in the aqueous phase. These intermediaries provide the necessary complexation capability without directly interfering with the main uranium extraction process or creating difficult-to-handle effluents, thus serving as a mediating solution between the extraction requirements and effluent management constraints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves decontamination factors for uranium from actinides that meet stringent standards, allowing for the elimination of the second uranium cycle while ensuring sufficient decontamination of fission products, thereby simplifying the processing and reducing costs.
Implementation Method 1
by complexing this actinide (IV)... by putting the organic phase in contact with an aqueous phase comprising nitric acid and at least one complexing agent which more strongly complexes actinides(IV) than uranium(VI)... said at least one complexing agent is a diglycolamide
Implementation Method 2
This is obtained by applying several purification cycles by liquid-liquid extraction... an organic phase which is not miscible with water... separating the organic phase from the aqueous phase
Data Source
AI summary
A method for processing a spent nuclear fuel is disclosed which includes a step for decontaminating uranium(VI) from one or more actinides(IV) and more specially from neptunium and/or plutonium, by complexing this (these) actinide(s)(IV). This method includes a step for decontaminating uranium (VI) from at least one actinide(IV), which decontaminating step comprises at least one operation for stripping the actinide(IV) from an organic phase, not miscible with water, and wherein uranium(VI) and the actinide(IV) are present, by putting the organic phase into contact with an aqueous phase comprising nitric acid and at least one complexing agent which more strongly complexes actinides(IV) than uranium(VI), and then separating the organic phase from the nitric aqueous phase, wherein the at least one complexing agent is a diglycolamide.