Stress Corrosion Cracking of Steam Generator Tubes in Alloy 690 TT: Effect of Sulfur and Lead on the Damage Mechanisms
Bibliographic record
Abstract
Abstract Outer diameter stress corrosion cracking (ODSCC) is an active and important degradation mode that affects steam generator (SG) tubes in Pressurized Water Reactors. This degradation mode is mostly due to the local and continuous accumulation of deleterious pollutants in confined areas, known as heat transfer crevices, in steam generators. Understanding the role of these pollutants, in particular lead and sulfur, in the degradation of SG tubes is a key gap in the safe long-term operation of Nuclear Power Plants (NPP). This study focuses on alloy 690 (Ni-30Cr-11Fe) Thermally Treated (TT) SG tubes, mainly used in French NPP. Reverse U-bend specimens made of alloy 690 TT were exposed for 7000 h at a temperature of 320 °C to simulated crevice environments. These environments included the presence of sludge, liquid and wet steam phases, polluted with S only or S combined with Pb. Post-exposure characterization of specimens extracted from the steam phase in the presence of S and Pb revealed intergranular stress corrosion cracking. At the nanoscale, traces of S and Pb were detected along the cracks, especially at the crack tip and at the oxide-metal interface.
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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".