Improved Engineering Process-Zone Model for Evaluation of Structural Strength of Annulus Spacers in CANDU Nuclear Reactors
Bibliographic record
Abstract
The core of a CANDU®(1) pressurized heavy water reactor consists of a lattice of either 390 or 480 horizontal Zr-Nb pressure tubes, depending on the reactor design, which contain the nuclear fuel. Each pressure tube is surrounded by a Zircaloy calandria tube that operates at a significantly lower temperature. Fuel channel annulus spacers maintain the annular gap between the pressure tube and the calandria tube throughout the reactor operating life. To meet this design requirement, the annulus spacers must have adequate structural strength to carry the interaction loads between the pressure tube and the calandria tube. Crush tests performed on specimens from Inconel X-750 spacers, both non-irradiated and ex-service, have demonstrated that their structural strength had degraded with operating time due to irradiation damage. An engineering process-zone model was developed and used to analyze the spacer crush test results, and to predict the maximum load carrying capacities of the Inconel X-750 spacer coils, as described in the companion paper “Engineering Process-Zone Model for Evaluation of Structural Strength of Fuel Channel Annulus Spacers in CANDU Nuclear Reactors” presented at the PVP2017 Conference. The developed model is based on the strip-yield approach of a process zone with a uniform restraining stress that represents the fracture region surrounded by elastic material. This baseline process-zone model has been improved by allowing the restraining stress to evolve with the variation in the opening displacement in accordance with a traction-separation constitutive relation. The development of this improved engineering process-zone model incorporating a non-trivial traction-separation constitutive relation is described in this paper.
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 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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.002 | 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".