Study of Hydrogen Evolution for the Outlet Rolled Joint of Candu Reactor Pressure Tube Under Operation Thermal Cycle
Bibliographic record
Abstract
Abstract Hydrogen is presented in CANDU reactor pressure tubes component as initial protium from manufacturing as well as deuterium ingress from heavy coolant occurring during operation. Ingress is more prominent at the rolled joint connection at each end of the pressure tube such that concentration gradients cause inboard diffusion of the hydrogen. High hydrogen concentration could reduce ductility and toughness of material via delayed hydride cracking (DHC) in nuclear reactor components such as pressure tubes. A finite element-based diffusion model, accounting for the ingress and redistribution interaction of protium and deuterium interaction, was developed to study the hydrogen evolution and redistribution at outlet rolled joint region of the pressure tube. To more precisely capture the hydrogen evolution by change in temperature for the reactor thermal cycle, temperature profiles calculated by thermal-hydraulic code, along with reactor startup/shutdown history was applied. This diffusion model predicts both protium and deuterium distributions in good agreement with measurements. The modelling results shows the temperature circumferential gradient is an important factor in redistributing the hydrogen concentration in the pressure tube. Sensitivity to input parameters (such as Terminal Solid Solubility (TSS), diffusivity) is seen to affect ratchetting responses of hydride accumulation at the top of the pressure tube. Modelling results also reveal that protium redistribution causes local increase in protium concentration.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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".