FY 2016 Progress Report on the ANL Sodium Draining and Refilling Experiments
Bibliographic record
Abstract
The main incentive for utilization of compact diffusion-bonded sodium-to-CO2 heat exchangers for a Sodium-Cooled Fast Reactor (SFR) with a supercritical carbon dioxide (sCO2) Brayton cycle power converter is the potential for reduction in heat exchanger size and cost relative to traditional shell-and-tube technology.There is an incentive for the designer to reduce the width of the sodium and CO2 channels as much as possible to realize the greatest size and cost reductions.However, there are practical limits on minimum channel size due to fundamental phenomena particular to sodium and CO2.One is that the channel size must be large enough to enable the rapid draining of sodium from the heat exchanger sodium channels in the event that a sodium leak is detected in an intermediate sodium heat transport system loop, in order to rapidly drain the sodium into the loop sodium storage vessel/tank and thereby limit the sodium mass released that could potentially burn if exposed to air.Information about the minimum sodium channel size can only be obtained by actually draining sodium from representative stainless steel sodium channels under prototypical conditions.It is not possible to obtain such information through modeling and simulation or through simulant experiments.The ANL Sodium Draining and Refilling experiment facility has been designed and is being assembled to obtain data on the draining of sodium from compact diffusionbonded sodium-to-carbon dioxide heat exchanger sodium channels including the mass of sodium drained versus time, the mass of sodium retained inside of the channels, and the potential for sodium to bridge the channel, freeze, and form a plug inside the channel versus the channel size.This information is needed to determine the minimum sodium channel size required to meet the requirements for sodium draining without bridges being left inside of the channels.Initial shakedown testing has been initiated using water and glass tubes before transitioning to sodium and stainless steel test sections.For the latter, the test sections will be heated to promote rapid sodium wetting of the stainless steel prior to draining.Testing with sodium will be initiated in FY 2017.
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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 | 0.006 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.019 | 0.007 |
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".