Studies of Zirconium Alloy Corrosion and Hydrogen Uptake During Irradiation
Bibliographic record
Abstract
The in-reactor corrosion and hydrogen pickup of Zircaloy-2 and Zr-2.5Nb pressure tube materials are being studied in two test loops: a light water loop in the NRU research reactor, and a new heavy water loop in the Halden reactor. The complimentary test programs examine the corrosion behavior of small specimens as a function of fast neutron flux and fluence, temperature, water chemistry, and specimen pre-oxidation. In NRU tests conducted over a range of reducing conditions (20 to 60 cm3 H2 · kg-1) at 568 K, Zr-2.5Nb specimens bearing “thin” prefilm oxides (⩽6 ηm) experience a reduction in oxidation rate influx. However, samples with thick prefilm oxides exhibit higher rates, suggesting that, like Zircaloy-2, rates for Zr-2.5Nb may increase as the oxide film continues to thicken. Initial results from the Halden program (5 to 7 cm3 D2 · kg-1) show that prefilmed specimens from tubes made of β-quenched material exhibit lower oxidation and deuterium pickup rates than tubes made from non-β-quenched materials. Prefilmed tubes made from β-quenched material also pickup a lower percentage of the D generated by the corrosion reaction. At high flux levels, prefilmed specimens from tube made of both materials exhibit a narrow range of percentage pickup values (4 to 5%), irrespective of temperature. A preliminary examination of activation energies over the range 523 to 598 K suggests significant differences in the temperature dependencies for oxidation and deuterium pickup of prefilmed specimens of tubes made from β and non-β-quenched Zr-2.5Nb. The differences are correlated with fast flux level.
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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".