Fuel Kernel Production Uniformity via Segmented Washing
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Solution Overview
Problem
The existing gel precipitation process for producing spherical fuel and breeder material kernels, particularly in the size range of 300 μm to 800 μm, faces challenges in maintaining uniformity and quality due to kinetic reactions and concentration changes during material exchange, leading to potential rupture, cracking, and uneven shrinkage, which affects the spherical shape and chemical composition.
Innovation Solution
The process involves separating microspheres from the precipitation bath using a first separator to ensure equal contact time with ammoniacal aging water, followed by a multistage cascade scrubber for thorough washing, and a controlled thermal treatment in a monolayer to achieve uniform shrinkage and chemical equilibrium, ensuring consistent kernel quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the gel precipitation process is used to produce larger kernels (300-800 μm), then the kernel size and volume increase, but the kinetic reactions and concentration changes worsen, leading to rupture, cracking, and uneven shrinkage
Solution Approach 1:
The patent applies preliminary action by conducting the precipitation process in a controlled manner before final kernel formation. The pouring solution is introduced dropwise into the precipitation bath, allowing gradual nucleation and growth of kernels. This controlled preliminary formation prevents sudden concentration changes that would cause rupture and cracking, enabling production of uniform large kernels (300-800 μm) without compromising manufacturing precision.
2Ease of manufacture
If the pouring solution is introduced dropwise into the precipitation bath, then kernel formation is controlled, but dilution with respect to ammonia occurs and concentration of ammonium nitrate and auxiliary agents increases, worsening product quality
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration parameters of the pouring solution and precipitation bath. The pouring solution contains uranyl nitrate at controlled concentrations, and the precipitation bath maintains specific ammonia concentration levels. By adjusting these parameters and controlling the dropwise addition rate, the patent achieves both ease of manufacture (controlled kernel formation) and manufacturing precision (consistent product quality), preventing excessive dilution and ammonium nitrate accumulation.
3Manufacturing precision
If washing is performed to remove ammonium nitrate and auxiliary agents, then purity increases, but water-soluble substances must be removed stepwise, increasing process complexity
Solution Approach 1:
The patent applies segmentation by dividing the washing process into multiple sequential steps with increasing ammonia concentration. The washing solution is prepared with progressively higher ammonia concentrations in each step, allowing systematic removal of ammonium nitrate and auxiliary agents from the kernels. This segmented approach achieves high kernel purity while managing process complexity through a structured, incremental washing sequence rather than a single complex operation.
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 ensures uniform diameter and spherical shape of the kernels, maintaining high density and exact chemical composition, addressing the issues of rupture, cracking, and quality variability, and enabling continuous production with consistent high-quality kernels.
Implementation Method 1
dripping a pouring solution containing uranyl nitrate into an ammoniacal precipitation bath for the formation of microspheres
Implementation Method 2
In the gel precipitation process referred to as external gelation, insoluble ammonium diuranate (ADU) forms
Implementation Method 3
the kinetics of the material exchange and the dynamics of the individual process steps for the preparation of uniform, rupture- and crack-free kernels
Implementation Method 4
drying as well as a thermal treatment
Implementation Method 5
a thermal treatment installation for drying and calcination
Data Source
AI summary
A method and an arrangement for producing spherical fuel cores and/or breeder material cores by dripping a pouring solution containing uranyl nitrate and a solution containing at least one auxiliary agent into an ammoniacal precipitation bath to form microspheres, aging, washing, drying, and thermally treating the microspheres. In order to provide a continuous production method along with a constantly high core quality, it is proposed that 1) the microspheres from the precipitation bath be separated through a first separator and fed to the ammoniacal aging water for aging, 2) the contact duration of the microspheres with the liquid of the precipitation bath before being introduced into the aging water be set equally or substantially equally, 3) the microspheres be transferred from the aging water to a multi-stage cascade scrubber using a transfer device, wherein the microspheres are washed in the multi-stage cascade scrubber so as to be free or substantially free from ammonium nitrate and at least one auxiliary agent contained in the microspheres, and 4) after drying, the microspheres be calcinated while distributed in a monolayer during a thermal treatment.