Fission-Product Release during Transient Heating of Irradiated CANDU Fuel
Bibliographic record
Abstract
A direct-electric-heating (DEH) apparatus was developed to heat Zircaloy-sheathed irradiated fuel samples. The apparatus was used in the temperature gradient 1 (TG1) experiment to measure fission product releases from Zircaloy-sheathed irradiated Canada deuterium uranium (CANDU) UO2 fuel samples during fast temperature ramps in the presence of a radial temperature gradient in the fuel. The ohmic heating of the UO2, combined with surface heat removal by the surrounding helium coolant flow, produced a radial temperature profile that approximates the profile for fission- or decay-heated fuel.The 11 tests conducted in the TG1 experiment simulated various transient heating rates and high-temperature annealing conditions. The results indicate that the DEH technique can produce large radial temperature gradients and rapid heating rates. Ceramographic examinations showed columnar grain growth and evidence of UO2 melting. Chemical interactions between the tungsten electrodes and the UO2 were also observed. Releases of krypton, and release and redistribution of cesium were measured. Fission product release and redistribution results from some of the tests are also reported.The Kr measurements indicated that the amount of Kr released was highly dependent upon the peak dwell power: The higher the dwell power, the higher the cumulative release. The redistribution of cesium was mapped using emission gamma radiography of the fuel specimen after the test. Cesium was released from the center of the fuel sample where temperatures were the highest. A well-defined area was confirmed near the center where the Cs activity was depleted. The measured Kr releases were in good agreement with the Cs migration and release.
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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 | 0.000 | 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".