High-Temperature CANDU Fuel Pin Deformation: Experiment and Model
Bibliographic record
Abstract
Due to the horizontal orientation of CANDU ® fuel channels, the fuel pins, which are assembled in bundles, may deform (sag) by gravity during high-temperature abnormal reactor events.Because excessive fuel pin and bundle deformation may affect the progression and consequences of potential accidents, a significant experimental and modeling program, mainly funded by CANDU ® Owners Group (COG), has been started at Atomic Energy of Canada Limited (AECL).The unique experimental set-up and instrumentation used for high-temperature single fuel pin deformation tests are presented in this paper.The deflection was measured by a laser light-stripe sensor travelling along the pin length.The fuel pin was supported near its ends and heated at about 1°C/s.Its deflection became readily detectable when the temperature reached 760 ± 10°C.The sag rate was between 0.019 and 0.010±0.002mm/s during 120 s hold periods at 800°C.During continued heating at 1°C/s, the sag rate increased significantly to about 0.20±0.01mm/s at temperatures above 870°C.The fuel pin sagged by >28 mm to contact the furnace tube at 970°C before reaching the 1000°C plateau.Experimental results of the fuel pin sag test have been compared with those of a computer simulation of the test using ANSYS models.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".