Material Surveillance of CANDU Zirconium 2.5%Wt Niobium Pressure Tubes
Bibliographic record
Abstract
There are 26 operating CANDU nuclear power plants, varying in size from 540 to 880 MW(e). The majority (18) of these plants are located in Canada, with others located in Argentina, Korea, China, and Romania. These plants entered commercial service at various times between 1971 and 2003. As such, some of the plants are more than 30 years old. In addition, there are new plants under construction and some older plants under refurbishment. Each plant contains between 380 and 480 fuel channels, for a total of almost 11,000 fuel channels currently in-service. A fuel channel is comprised a Zr-2.5%Nb pressure tube, stainless steel endfittings, a zircaloy-2 calandria tube, and a series of annulus spacers (Figure 1). The pressure tube serves to: i) Support and locate the nuclear fuel bundles, ii) Form part of the pressure boundary of the heavy water coolant system, and iii) Provide an additional boundary between the nuclear fuel and the external environment.
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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 | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".