Assessing microbially influenced corrosion of titanium as novel canister material for geological disposal facilities
Bibliographic record
Abstract
• Comprehensive XPS, micro-FTIR and SEM-EDX characterisation of Titanium surfaces. • Titanium surface showed exceptional resistance to biotically amended GDF-like conditions. • No pitting, corrosion, or TiS formation was detected on the surface after prolonged exposure. • TiO 2 passive layer remained stable under worst-case biotically stimulated scenario. • Study supports titanium structural viability as nuclear waste canister material. In response to the growing global inventory of nuclear waste and the urgent need for secure long-term disposal solutions, geological disposal facilities (GDFs), also known as deep geological repositories, are being pursued worldwide. Several national programmes, including those in the UK, Japan, and Canada, are evaluating corrosion-resistant alloys for waste canisters. Among these, novel materials such as titanium alloys have emerged as promising candidates due to their protective TiO 2 films. However, the threat of microbial corrosion under repository-relevant conditions remains highly unexplored. To address this, titanium discs (grade 2, ASTM B348) were incubated in bentonite slurries with synthetic pore-water at 30 °C and 60 °C under strictly anoxic, dark conditions, mimicking deep underground GDF environments. Electron donors (acetate, lactate) and an electron acceptor (sulphate) were added to stimulate microbial activity and assess long-term canister performance. All titanium samples retained an intact TiO 2 layer with no detectable pitting or localised damage. Microscopic (SEM) and spectroscopic (XPS) analyses showed slight thinning of titanium oxide films and microbial presence co-located with bentonite, but no evidence of corrosion products or metal loss. Micro-FTIR showed functional groups associated with microbial presence (proteins, lipids, and polysaccharides) in the bentonite, but not on titanium surfaces. The experimental design aimed to promote bacterial activity to simulate worst-case GDF biotic conditions. These findings demonstrate titanium’s exceptional stability against microbially influenced corrosion (MIC) in stimulated GDF-like environments. This study supports the structural viability of titanium canisters for nuclear waste disposal and underscores the importance of considering microbial factors in long-term corrosion assessments.
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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 | 0.001 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".