Abstract
Following earlier field-scale pilot work on nuclear site materials in the late 2000s, there has recently been renewed research and industry interest in the application of electrokinetic technologies for nuclear site management and remediation in the UK. One relatively novel application of electrokinetics is the use of sacrificial steel electrodes (coupled with an in situ generated pH-Eh gradient in the treated material) to precipitate sub-surface iron-rich barriers for groundwater and/or leachate containment, which could be used to grout or contain contaminated fluids in the sub-surface on working nuclear sites or sites undergoing decommissioning. Here, we report previously unpublished data from two work programmes exploring the higher Technology Readiness Level (TRL) application of this electrokinetic iron-barrier approach to materials typical of those found in the subsurface of the Sellafield nuclear licensed site, UK. The first programme, funded by the UK National Nuclear Laboratory (NNL), assessed the electrokinetic generation of iron-rich barriers at metre + scale in simulated Sellafield materials, while the second programme, funded under the current UK TRANSCEND consortium project, examined electrokinetic iron-barrier formation at smaller (<1 m) scale, but in real site materials. Both programmes indicate that iron-rich barriers can be conveniently and electrokinetically grown in different geometries over reasonable timescales (months) in realistic site subsurface materials (sands), in electrolytes similar to natural waters found in the environment. Voltage requirements are low (<1 V cm −1) with energy and consumables costs of no more than single-digit or tens of US dollars at the metre-plus scale. Further work is needed however to assess the longevity of the iron precipitates forming the subsurface barrier, and to explore barrier generation at the geometries and scales required for (site specific) field application.
| Original language | English |
|---|---|
| Pages (from-to) | 652-662 |
| Number of pages | 11 |
| Journal | Environmental Science: Advances |
| Volume | 2 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 6 Mar 2023 |
Bibliographical note
Funding Information:The authors thank the NDA, NNL and predecessors as well as authors for kindly providing access to many reports described here. The authors also thank GAU-Radioanalytical at the University of Southampton for experimental support. Part of this work has been funded through the TRANSCEND (TRANsformative SCience and Engineering for Nuclear Decommissioning) consortium from the UK's Engineering and Physical Sciences Research Council, EPSRC (reference EP/S01019X/1). We also acknowledge support from the National Nuclear User Facility EXACT (Next Generation Accelerated Characterisation Technologies), via EPSRC grant EP/T011548/1. We thank two anonymous reviewers for comments that improved the overall discussion of the data presented and its wider implications.
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© 2023 RSC.