Residual Stresses in CANDU Feeder Bends: Comparison of Measurements and Predictions
Bibliographic record
Abstract
In one CANDU® nuclear station, 11 outlet feeder pipes have been replaced because of cracking in the bends (9 of them were detected before leaked). The cracked feeder bends, which were made out of SA-106 Grade B material, were 2.5 inches (64 mm) in nominal diameter and with a small bend radius of 3.75 inches (95 mm). In all cases, cracks were primarily axial in orientation and were initiated either on the inside surface along the flanks of the bends or on the outside surface along the extrados of the bends. Root cause analyses indicated that the residual stress played a significant role in these failures. Measured residual stresses data from ex-service and spare feeder bends have been used to identify possible crack locations, to evaluate susceptibility to cracking of various feeder bends and to develop inspection strategies in limited-scope inspection campaigns. This paper documents the numerical prediction of residual stresses in feeder bends and compares these data with field measurements.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".