Oxidation Study of Incoloy 800H Tubes Exposed to Super-Heated Steam and Supercritical Water
Bibliographic record
Abstract
Incoloy 800H, a high-nickel austenitic alloy, has great merit for use in Supercritical Water (SCW). The development of the CANada Deuterium Uranium (CANDU) nuclear Supercritical Water Reactor (SCWR) was the driving force behind this research to investigate the oxidation performance of Incoloy 800H for use as fuel cladding. The oxidation behaviour of Incoloy 800H was investigated in Super-Heated Steam (SHS) and in SCW using novel tube specimens. Four specimen configurations were prepared to have a combination of Open-Ends (OE) or Closed-Ends (CE) with either a Bare Surface (BS) or a NiCrAlY Coated Surface (CS). The OE and CE specimens experienced different through-thickness stress distributions due to their testing environment, which allowed comparison and characterization of their performance with regard to oxidation and stress. Standard mass and dimension change measurements performed on the test specimens were observed to be unreliable for characterizing the relative oxidation between different test environments and specimen configurations. Detailed metallographic studies were made with the aid of optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersion Spectrometry (EDS), and X-Ray Diffraction (XRD), in addition to mass and dimensional measurements. Finite Element Analysis (FEA) was performed to determine the effect that specimen configuration and testing environment have on the stress distributions within the specimens. Testing showed that BS specimens in SHS and SCW produced sufficiently similar oxidation behaviours and oxide scales; spallation of the outer Fe-rich oxide layer was believed to have occurred. The CS specimens formed a thin and discontinuous oxide under both SHS and SCW. The CE/BS tube yielded and collapsed when exposed to SCW with cracks and ‘folds’ vulnerable to oxidation forming on the collapsed surfaces. The NiCrAlY coating provided sufficient strength to reinforce the CE/CS tube preventing its collapse in SCW conditions. From the perspective of oxidation performance, it has been determined that SHS (625oC, 0.1 MPa) is a suitable medium for investigating the oxidation behaviour of Incoloy 800H in SCW (625oC, 26.14 MPa) and would provide comparatively conservative results. The coating affords the tube additional protection from both oxidation and stress, providing the potential of extending the operating life of the Incoloy 800H tubes.
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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) | 0.001 | 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) | 0.000 | 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".