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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.005 | 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 teacher head, 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".