Results of Air Barbotage Experiments Simulating Two-Phase Flow in a CANDU End Shield During In-Vessel Retention
Bibliographic record
Abstract
This paper presents the results of experimental investigations into two-phase mass transport in a coarse packed bed representing the Canada Deuterium Uranium (CANDU) end shield. This work contributes to understanding of phenomena impacting in-vessel retention (IVR) during postulated severe accidents in CANDU reactors. The air barbotage technique was used to represent boiling at the calandria tubesheet surface facing the inner cavity of the end shield. Qualitative observations of the near-wall two-phase region were made during air injection. In addition, flow visualization was carried out through the addition of dye to the water. Air flow rate, shielding ball diameter, and cavity dimensions were varied within relevant ranges; and the impact of these parameters on the near-wall region was identified. A brief review of the relevant knowledge base is presented, allowing demonstration of the applicability of the test parameters. The observed phenomena are compared to published results involving similar geometries with capillary porous media.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".