An in-situ Study of the Aqueous Speciation of Uranium (VI) Under Hydrothermal Conditions
Bibliographic record
Abstract
Rigorous study of the speciation distribution of uranyl-chloride bearing solutions under hydrothermal conditions is important to understand the transport mechanism of uranium underground, which is of uttermost interest to parties studying the geological uranium deposits and those studying the possibilities of geological repositories for spent nuclear waste. I report an in-situ Raman spectroscopic study of the speciation distribution of aqueous uranyl-chloride complexes upto 500°C conducted using a HDAC as the high PT spectroscopic cell. The samples studied contained the species UO22+, UO2Cl+, UO2Cl20 and UO2Cl3- with varying contributions at different temperature and chloride concentration conditions. Raman vibrational peak positions and the FWHM were determined for each of the identified species, and speciation distribution graphs were plotted for different temperature and concentration points. The results obtained are in good agreement with the published room temperature data and also with a high temperature study performed using UV-Vis spectroscopy technique. To confirm and complement the knowledge obtained from optical spectroscopy techniques like Raman spectroscopy and UV-Vis spectroscopy, x-ray absorption spectroscopy experiments are very useful, but the use of radioactive samples under high pressure and temperature conditions in synchrotron x-ray facilities requires strict protocols and a special radiological containment system. I designed and assembled a radiological enclosure system for HDAC suited for synchrotron x-ray absorption spectroscopy experiments on aqueous actinide samples upto high temperature and pressure. This enclosure was successfully tested at APS and SSRL after the approval from radiological safety committee of the respective facilities. XAS data were collected from the uranyl samples upto 500°C and were found to be of comparable quality to those from similar experiments on non-rad samples without the use of enclosure. One representative set of x-ray absorption spectra for aqueous uranyl-chloride bearing sample upto 500°C is presented in this thesis.
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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 | 0.000 | 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) | 0.001 | 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".