Modelling of Local Hydrogen Isotope Concentration at Rolled Joints of CANDU Reactor Fuel Channels and Evaluation of Potential Interaction With an Adjacent Flaw
Bibliographic record
Abstract
Abstract The pressure tubes in CANDU-PHWR (Pressurized Heavy Water Reactor) are subject to various ageing related degradation mechanisms, including ingress of deuterium, which is a hydrogen isotope, through a corrosion reaction with the heavy water coolant. Pressure tube structural integrity is dependent on the hydrogen equivalent concentration, Heq, which accounts for both hydrogen and deuterium, and increases with reactor operating time. In recent Heq measurements, high Heq levels were observed at local areas of some pressure tubes that were in service for long operating times. This local area of high Heq is referred to as a “blip”. This paper investigates the modelling of blip formation at the inlet rolled region and its interaction with an incident postulated blunt flaw residing on the pressure tube inside surface at the blip axial location using a comprehensive three-dimensional finite element diffusion model of the fuel channel and a set of generic inputs. The analysis results indicate that the presence of a blip has a minimal effect on the build-up of hydrides at a postulated blunt flaw-tip of a flaw residing at the pressure tube inside surface at the blip axial location over long operating times.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".