UO2 Powder Mixing for Consistent Nuclear Fuel Density
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Solution Overview
Problem
The variability in sinterability of uranium dioxide powders from different synthesis processes leads to inconsistent densification and dimensionality issues in nuclear fuel production, requiring complex adjustments and material loss during processing.
Innovation Solution
A process involving a vibrating mill to mix uranium dioxide powders from different synthesis processes, fragmenting agglomerates and aggregates while preserving crystallite size, followed by compaction and sintering to achieve consistent sinterability and density across varying agglomeration states and shaping stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If uranium dioxide powders from different synthesis processes are used directly, then production flexibility is improved, but sinterability consistency deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a pre-treatment step on powders from different synthesis processes before sintering. This pre-treatment standardizes the physical and chemical properties of diverse powders, ensuring consistent sinterability while maintaining the flexibility to use various powder sources. The pre-treatment creates a uniform intermediate state that eliminates variability introduced by different synthesis methods.
Solution Approach 2:
The patent utilizes parameter changes by modifying key parameters such as particle size distribution, surface area, and chemical composition through controlled processing. By adjusting these parameters to specific ranges, the patent ensures that powders from different synthesis processes achieve consistent sinterability. This parameter standardization allows flexible powder selection while guaranteeing reliable sintering outcomes.
2Reliability
If complex adjustments are made to ensure consistent densification, then sinterability consistency is improved, but device complexity increases
Solution Approach 1:
The patent extracts and addresses the root cause of sinterability variability through a dedicated pre-treatment step. By isolating the standardization process into a separate, focused operation, the patent simplifies the overall process architecture. This extraction eliminates the need for complex adjustments throughout subsequent processing stages, as consistency is established upfront.
Solution Approach 2:
The patent employs controlled parameter changes within a standardized pre-treatment process to achieve consistent sinterability. By confining parameter adjustments to a specific, well-defined step rather than distributing complex controls throughout the entire process, the patent reduces overall device complexity while maintaining reliability.
3Manufacturing precision
If complex adjustments are made during processing, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by performing all necessary standardization in a pre-treatment step before sintering. This upfront preparation ensures consistent densification outcomes without requiring time-consuming adjustments during the main processing stages. The preliminary action consolidates precision-enhancing operations into a single, efficient step.
Solution Approach 2:
The patent enables skipping of complex adjustment steps by establishing consistency through pre-treatment. Once powders are standardized in advance, the subsequent sintering process can proceed directly without intermediate adjustments, effectively rushing through what would otherwise be time-consuming refinement stages while maintaining manufacturing precision.
4Adaptability or versatility
If powders with varying agglomeration states are used, then adaptability is improved, but sinterability varies
Solution Approach 1:
The patent applies preliminary action by implementing a pre-treatment step that standardizes the agglomeration state of powders from different sources. This pre-treatment breaks down varying agglomerate structures into a consistent size distribution, ensuring uniform sinterability while maintaining the ability to use diverse powder sources. The preliminary action creates a common physical state regardless of origin.
Solution Approach 2:
The patent utilizes parameter changes by controlling particle size distribution and agglomeration characteristics through the pre-treatment process. By adjusting these physical parameters to specific target ranges, the patent eliminates variability in sinterability while preserving adaptability to different powder sources. The parameter standardization transforms diverse agglomeration states into a uniform condition suitable for consistent sintering.
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 process ensures reproducible and flexible production of nuclear fuel with consistent sinterability and density, reducing the need for complex adjustments and minimizing material loss, while allowing for the use of diverse powder sources without mixing issues.
Implementation Method 1
using said vibrating mill, the powders are stirred, in order to form a particulate matter, the grinding intensity being sufficient to fragment the agglomerates and aggregates present in the powders
Implementation Method 2
the grinding intensity being sufficient to fragment the agglomerates and aggregates present in the powders without however fragmenting the crystallites present in the powders
Implementation Method 3
a shaping stress is applied to said particulate material, generally from 200 to 1200 MPa, preferably from 200 to 1000 MPa, more preferably from 200 to 600 MPa, even more preferably from 300 to 500 MPa, in order to obtain a compact material
Implementation Method 4
the said compact material is sintered so as to obtain the dense material
Implementation Method 5
the said compact material is sintered so as to obtain the dense material
Data Source
Figure 1
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AI summary
The invention concerns a method for making dense material containing UO2, including: a) introducing in a grinder at least two powders comprising each UO2, obtained by two different synthesis methods and having neighbouring specific surfaces; b) stirring said powders in said grinder, to form a particulate material, the grinding intensity enabling the powder agglomerates and the aggregates to be fragmented without the powder crystallites being fragmented, and the grinding energy being such that all the agglomerates and the aggregates are destroyed; c) introducing said particulate material into a mould; d) applying on said particulate material a shaping stress, so as to obtain a compact material; e) sintering said compact material to obtain the dense material.