A Comparison of Reactivity Parameters of CANDU Fuel Bundles over Fuel Lifetime
Bibliographic record
Abstract
Two important parameters for safety analysis of CANDU fuel are the coolant void reactivity (CVR) and the adjuster rod reactivity worth near the fuel. In this study the CVR and adjuster rod worth of two CANDU fuel designs, the standard 37 element natural uranium bundle and the 43 element CANDU Flexible Fuelling (CANFLEX) bundle containing slightly enriched uranium are compared over the useful life of the fuel. Analysis of the neutron multiplication factor of each bundle found that the useful life of the CANFLEX fuel is approximately 32 days longer than the standard CANDU fuel. The plutonium peak, a well-known trait of natural uranium CANDU fuel, was not observed in CANFLEX fuel design. It was found that the presence of a burnable neutron absorber in the centre pin of the CANFLEX fuel reduces CVR by approximately 55%, from about 16.2 mk for the natural uranium fuel to 7.0 mk for CANFLEX before irradiation. The worth of adjuster rods near CANFLEX fuel was found to vary by approximately 5 mk over the life of the fuel. Adjuster rods became more effective as the CANFLEX fuel was irradiated. Standard CANDU fuel exhibits different behaviour. The adjuster rod reactivity becomes less negative for the first 100 days of the fuel cycle before dropping to within 1 mk of the fresh fuel reactivity worth at the end of the useful life. The standard CANDU fuel bundle is a safer design during normal operating conditions, while the CANFLEX fuel bundle is safer during a loss of coolant accident.
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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".