MICROSTRUCTURAL ANALYSIS OF HELIUM DISTRIBUTION IN NICKEL AND INCONEL X750
Bibliographic record
Abstract
Nickel alloys have found ever increasing use in the nuclear sector in recent times. Inconel X750 and other nickel-based alloys are used in the construction of reactor fuel channels. Thermal neutrons cause transmutation of nickel, and the nuclear reactions that take place within some nuclear reactor components result in the production of helium. Helium accumulation causes the swelling, reduces material strength and finally leads to failure. This project addresses two impact areas, viz., i) improving safety of nuclear energy systems and, ii) advancing knowledge on nuclear materials used in CANDU (Canada Deuterium Uranium) reactors. The project discusses the experiments carried out on helium irradiated pure Ni and Inconel X750 alloy in order to understand void formation due to helium. SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscopy) analyses were carried out to establish a relationship between helium void formation and temperature. In addition, EBSD (Electron Backscattered Diffractometry) analysis was carried out to analyse the concentration of helium voids at various grain boundaries. The project explains in detail the use of SPECTER code to calculate the gas production levels and DPA (displacement per atom) and SRIM (Stopping and Range of Ions in Matter) software, which was used to carry out the various calculations necessary to perform helium ion implantation experiments. As it was difficult to work with irriadted materials from the reactor on account of safety concerns, and also cost associated with working with heavily irradiated materials, the method of helium ion implantation was adopted for this project. Results showed that at higher temperatures both irradiated pure Ni and Inconel X750 alloy showed accumulation of voids towards the grain boundaries. TEM and EDS (Energy Dispersive Spectroscopy) analysis on irradiated pure Ni confirmed the presence of voids near the grain boundaries. A statistical relationship was also established between the accumulation of voids and the grain boundary misorientation. It was found out that for both irradiated pure Ni and Inconel X750 alloy the concentration of voids increased with an increase in the grain boundary misorientation. This was due to more free volume available at higher angle grain boundaries.
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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 | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".