Microstructured Nuclear Fuel Separation via Fluidized-Bed CVD
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Solution Overview
Problem
Current nuclear fuel processing methods are complex and costly, particularly in separating fission products from fissile material after use in reactors, as they require expensive and hazardous enrichment and separation processes.
Innovation Solution
Microstructured nuclear fuels with micrometer-scale fissile material structures dispersed in a matrix material, allowing fission products to escape and come to rest in the matrix, enabling efficient separation through size reduction and selective dissolution after cooling, using a fluidized-bed chemical vapor deposition reactor with pneumatic and electric vibrators for uniform coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional nuclear fuel processing methods are used, then fuel can be manufactured and used in reactors, but the separation of fission products from fissile material becomes complex and costly
Solution Approach 1:
The fuel is segmented into discrete micrometer-scale fissile material structures (particles, spheres, or rods) dispersed in a matrix material. This segmentation allows fission products to be contained within individual structures while remaining separated from the bulk fissile material, enabling simpler post-irradiation separation processes where entire structures can be filtered or centrifuged rather than requiring complex chemical separation of dissolved components
Solution Approach 2:
The invention extracts the fission products from the bulk fissile material by confining them within discrete micrometer-scale structures embedded in a matrix. This physical extraction approach allows fission products to be removed from the fuel cycle along with the matrix material through simple mechanical separation methods, avoiding the need for complex reprocessing operations
2Ease of manufacture
If microstructured fuels with micrometer-scale fissile material structures are used, then fission products can escape to matrix material for easier separation, but the manufacturing process becomes more complex requiring fluidized-bed CVD reactors
Solution Approach 1:
The invention merges multiple functions into the fluidized-bed CVD reactor: particle heating, matrix material deposition, and uniform coating formation all occur simultaneously in a single apparatus. The fluidized bed state combines particle suspension, heat transfer, and mass transfer processes, enabling efficient in-situ formation of the microstructured fuel with uniform matrix coating around each fissile particle
Solution Approach 2:
The invention replaces traditional mechanical coating methods with chemical vapor deposition. Instead of physically applying matrix material to particles, volatile precursors are introduced that decompose and deposit matrix material chemically onto the particle surfaces during fluidization, achieving uniform coatings without complex mechanical coating equipment
3Manufacturing precision
If uniform powder coating is achieved in fluidized-bed reactor, then microstructured fuel can be produced, but vibration and powder entrainment challenges arise
Solution Approach 1:
The invention applies mechanical vibration to the fluidized bed to prevent powder entrainment and promote uniform coating. The vibration keeps particles in constant motion and prevents them from being carried away by gas flow, while also ensuring uniform exposure of all particle surfaces to the depositing matrix material, achieving both containment and coating uniformity
Solution Approach 2:
The invention uses pneumatic control of gas flow to manage the fluidized bed. By carefully controlling gas velocity and distribution, the system maintains particles in a fluidized state for coating while preventing excessive gas velocity that would cause entrainment. The pneumatic system allows precise adjustment of flow conditions to balance coating efficiency with particle retention
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 significantly reduces the cost of fuel cycle operations by facilitating the separation of fissile material from fission products, allowing for reuse of fissile material and safe disposal of fission products and matrix material, thus enhancing the efficiency and safety of nuclear fuel management.
Implementation Method 1
a fluidized-bed chemical vapor deposition reactor including a gas inlet for providing controlled gas flow into a particle coating chamber
Implementation Method 2
at least one pneumatic and electric vibrator is operationally coupled to the particle coating chamber for causing vibration of the particle coater to promote uniform powder coating
Implementation Method 3
a lower bed hot zone region to contain powder, and an upper bed region to enable powder expansion
Data Source
AI summary
Microstructured nuclear fuel adapted for nuclear power system use includes fissile material structures of micrometer-scale dimension dispersed in a matrix material. In one method of production, fissile material particles are processed in a chemical vapor deposition (CVD) fluidized-bed reactor including a gas inlet for providing controlled gas flow into a particle coating chamber, a lower bed hot zone region to contain powder, and an upper bed region to enable powder expansion. At least one pneumatic or electric vibrator is operationally coupled to the particle coating chamber for causing vibration of the particle coater to promote uniform powder coating within the particle coater during fuel processing. An exhaust associated with the particle coating chamber and can provide a port for placement and removal of particles and powder. During use of the fuel in a nuclear power reactor, fission products escape from the fissile material structures and come to rest in the matrix material. After a period of use in a nuclear power reactor and subsequent cooling, separation of the fissile material from the matrix containing the embedded fission products will provide an efficient partitioning of the bulk of the fissile material from the fission products. The fissile material can be reused by incorporating it into new microstructured fuel. The fission products and matrix material can be incorporated into a waste form for disposal or processed to separate valuable components from the fission products mixture.