Actinide Oxalate Fluidised Bed Precipitation
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Solution Overview
Problem
Current methods for preparing actinide oxalates in the nuclear fuel cycle face challenges such as dispersed granulometric distributions, fine dust generation, and limited production capacity, which affect the handleability, filterability, and flowability of actinide oxides used in nuclear fuel pellets, posing risks of contamination and requiring optimized reactor designs.
Innovation Solution
A method involving the precipitation of actinides in a fluidised bed reactor using an aqueous solution of oxalic acid, with controlled concentrations and excess oxalic acid to form actinide oxalate powders with improved granulometry and morphological characteristics, reducing dust generation and enhancing handling and filtration properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional stirred reactors are used for actinide precipitation, then the precipitation process is simple to operate, but the precipitates have dispersed granulometric distribution with very fine dust generating particles
Solution Approach 1:
The patent replaces traditional stirred reactors with a fluidised bed reactor, substituting the mechanical stirring system with a fluidisation system where upward gas or liquid flow suspends the particles. This substitution eliminates the dispersed granulometric distribution and fine dust generation while maintaining operational simplicity, as the fluidised bed automatically provides uniform particle suspension and growth conditions.
2Manufacturing precision
If rotating disc reactor is used for actinide precipitation, then the precipitates have narrower granulometric distribution, but there are problems of scaling and accumulation of materials
Solution Approach 1:
The patent replaces the rotating disc mechanical system with a fluidised bed system. The fluidised bed reactor uses upward flow to suspend and fluidise particles, eliminating the need for large diameter rotating discs. This substitution resolves scaling problems and material accumulation issues while maintaining narrow granulometric distribution through uniform fluidisation conditions.
3Device complexity
If Rushton turbine is used to replace disc, then the shear rate increases and scaling problems are reduced, but the granulometry deteriorates due to attrition phenomena
Solution Approach 1:
The patent replaces the Rushton turbine mechanical agitation system with a fluidised bed system. Instead of using high shear rate mechanical stirring that causes particle attrition, the fluidised bed uses gentle upward flow to suspend and fluidise particles. This substitution eliminates granulometry deterioration from attrition while maintaining reduced scaling problems.
4Manufacturing precision
If Vortex effect reactor is used for actinide precipitation, then the granulometric and morphological characteristics are improved, but the production capacity is limited due to criticality reasons
Solution Approach 1:
The patent applies fluidised bed technology that can handle multiple actinide types and configurations (UO2, PuO2, mixed oxides) while maintaining excellent granulometric characteristics. The fluidised bed reactor design allows scaling up production capacity by increasing bed volume or operating in continuous mode, unlike the Vortex effect reactor which is limited by criticality constraints.
5Productivity
If fluidised bed reactor is used for actinide precipitation, then the production capacity increases and reactor dimensions are reduced, but new challenges in maintaining fluidisation and preventing particle attrition arise
Solution Approach 1:
The patent uses fluidised bed technology which replaces complex mechanical agitation systems with simpler gas or liquid flow-based fluidisation. The system maintains particles in suspension through controlled upward flow, enabling high production capacity in compact reactors. The fluidisation control, while requiring careful flow rate management, eliminates the need for complex mechanical stirring mechanisms.
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
The method produces actinide oxalate powders with spherical particles and controlled granulometry, improving filterability and flowability, reducing contamination risks, and enabling high-rate production in reduced reactor dimensions, addressing scaling and accumulation issues while maintaining reactor safety and efficiency.
Implementation Method 1
precipitation in fluidised bed
Implementation Method 2
the precipitation or coprecipitation is carried out in fluidised bed
Data Source
AI summary
A method for preparing an oxalate of one or more actinides for processing and recycling nuclear fuel, comprising: the precipitation of said actinide or the coprecipitation of said actinides in the form of oxalate particles by bringing into contact an aqueous solution containing the actinide(s) with an aqueous solution of oxalic acid or of an oxalic acid salt; and the collection of the resulting oxalate particles; characterized in that the precipitation or coprecipitation is carried out in fluidized bed.