Interface-associated microbial growth in anoxic pressure vessels containing compacted gapfill bentonite
Bibliographic record
Abstract
AIMS: Deep geological repositories (DGR) for belowground storage of used nuclear fuel rely on highly compacted bentonite to limit growth of microorganisms, including those that can contribute to microbiologically influenced corrosion, like sulfate-reducing bacteria (SRB). This study examined how a range of bentonite dry densities (1.25-1.60 g cm-3) affected microbial community abundance and composition in bentonite incubated in pressure vessels for 1, 4, or 12 months under anoxic conditions. RESULTS: Culturable heterotroph abundance increased in some lower-density (i.e., 1.25 and 1.40 g cm-3) samples after 1 month, consistent with previous experiments. Unlike previous studies, outer layer bentonite samples had higher abundances of culturable SRB than the starting material. SRB-associated sequences were more prevalent in swabs from pressure vessel surfaces than in bentonite, suggesting interface-associated SRB growth. CONCLUSIONS: Although culturable SRB increased for several outer layer pressure vessel samples, abundances remained relatively low and did not increase beyond the values measured at the 1-month timepoint. Overall, a minimum dry density of 1.45 g cm-3 limited microbial growth in inner layer bentonite samples.
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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) | 0.001 | 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 | 0.001 |
| 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".