Irradiation-Induced Embrittlement of INCONEL 600 Flux Detectors in CANDU Reactors
Bibliographic record
Abstract
The early design of flux detectors in use in CANDU® reactors consisted of multiple-paired-coiled detectors sheathed in INCONEL® 600 and wrapped around a Zircaloy carrier rod. The signal from these detectors was carried by INCONEL 600 coaxial cables that were threaded through the carrier-rod and fed back to instrumentation outside of the reactor core. Failures occurred in early applications that were related to the environment in which the detectors operated (moist or dry air). These failures were mitigated by ensuring that the detectors operated with a He cover gas that acts both to limit corrosion and as an efficient conductor of heat (generated by nuclear heating). An improved design was introduced consisting of single-individual-replaceable detectors (SIRs) with performance improved by eliminating brazed joints that were susceptible to nitric acid attack. Post-irradiation examination of encapsulated INCONEL 600 coiled flux detectors that had failed after several years of service in a CANDU reactor showed that many of the detector wires inside the carrier rod were broken. It was concluded that failure occurred because the He cover gas was lost and replaced by air. The examination also showed that those parts of the INCONEL 600 detector wires that had operated at the highest temperature, as evidenced by the degree of localised corrosion, were the most severely embrittled. Parts of the same detector wires that were clearly operating at lower temperatures, because they were shiny, remained ductile. Calculations indicate that if the INCONEL 600 material temperature exceeds about 573K (300°C) then it is conceivable that significant swelling and associated embrittlement could be expected. This is consistent with the observations indicating that the INCONEL detector wires that had experienced operation at elevated temperatures (>300°C) were embrittled.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".