Production of Uniformly Sized Liquid Droplets Using a Vibrating Needle for TRISO Fuel Fabrication
Bibliographic record
Abstract
Abstract Several small modular nuclear reactors propose to use TRISO (TRistructural ISOtropic) fuel as part of their reactor design, due to their ability to withstand higher coolant temperatures. TRISO fuel particles require the fabrication of uranium oxycarbide kernels with a diameter of approximately 0.5 mm. One of the common production processes of the TRISO kernels involves generating droplets by using a vibrating needle to dispense a uranium nitrate solution into an ammonium hydroxide solution, leading to the formation of gelled microspheres. A cylindrical liquid jet is naturally unstable due primarily to the Plateau–Rayleigh instability. When an external mechanical vibration is applied to the jet flow, it disperses into a stream of uniformly sized droplets. The droplet size is determined by the frequency and amplitude of the mechanical vibration. The main aim of this study is to investigate the effect of applying transverse vibrations to a needle issuing a stream of liquid, to break up the stream and produce uniform-sized droplets. Resonating the needle tip can influence droplet formation by enhancing the instability of the liquid at the tip, promoting the formation of droplets. As the needle vibrates at resonant frequencies, it may create oscillations in the fluid that lead to the detachment of small, uniform droplets. A prototype vibrating needle test rig was designed and constructed to study the breakup behavior of water, a Newtonian fluid, and zirconia slurry, a non-Newtonian fluid, discharged from a 19-gauge needle under externally controlled mechanical vibrations. The jet breakup characteristics, including breakup length, droplet diameter, and shape, were examined as functions of vibration frequency (80 Hz - 160 Hz), amplitude, and jet flow velocity (0.5 m/s - 1.0 m/s). The results for water flow showed that vibrating the needle caused the jet stream to bifurcate into two parallel streams, each consisting of uniformly sized droplets. Increasing the jet velocity resulted in a reduction in droplet diameter. Furthermore, the vibration amplitude appeared to influence the bifurcation behavior, leading to the formation of either two or four jet streams.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".