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Barton F, Shaw S, Morris K, Graham J, Lloyd JR. Impact and control of fouling in radioactive environments. PROGRESS IN NUCLEAR ENERGY 2022. [DOI: 10.1016/j.pnucene.2022.104215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Williamson AJ, Lloyd JR, Boothman C, Law GTW, Shaw S, Small JS, Vettese GF, Williams HA, Morris K. Biogeochemical Cycling of 99Tc in Alkaline Sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:15862-15872. [PMID: 34825817 DOI: 10.1021/acs.est.1c04416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
99Tc will be present in significant quantities in radioactive wastes including intermediate-level waste (ILW). The internationally favored concept for disposing of higher activity radioactive wastes including ILW is via deep geological disposal in an underground engineered facility located ∼200-1000 m deep. Typically, in the deep geological disposal environment, the subsurface will be saturated, cement will be used extensively as an engineering material, and iron will be ubiquitous. This means that understanding Tc biogeochemistry in high pH, cementitious environments is important to underpin safety case development. Here, alkaline sediment microcosms (pH 10) were incubated under anoxic conditions under "no added Fe(III)" and "with added Fe(III)" conditions (added as ferrihydrite) at three Tc concentrations (10-11, 10-6, and 10-4 mol L-1). In the 10-6 mol L-1 Tc experiments with no added Fe(III), ∼35% Tc(VII) removal occurred during bioreduction. Solvent extraction of the residual solution phase indicated that ∼75% of Tc was present as Tc(IV), potentially as colloids. In both biologically active and sterile control experiments with added Fe(III), Fe(II) formed during bioreduction and >90% Tc was removed from the solution, most likely due to abiotic reduction mediated by Fe(II). X-ray absorption spectroscopy (XAS) showed that in bioreduced sediments, Tc was present as hydrous TcO2-like phases, with some evidence for an Fe association. When reduced sediments with added Fe(III) were air oxidized, there was a significant loss of Fe(II) over 1 month (∼50%), yet this was coupled to only modest Tc remobilization (∼25%). Here, XAS analysis suggested that with air oxidation, partial incorporation of Tc(IV) into newly forming Fe oxyhydr(oxide) minerals may be occurring. These data suggest that in Fe-rich, alkaline environments, biologically mediated processes may limit Tc mobility.
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Affiliation(s)
- Adam J Williamson
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K
- CENBG-Équipe Radioactivité et Environnement, UMR 5797, CNRS-IN2P3/Université de Bordeaux, 19 chemin du Solarium, CS 10120, 33175 Gradignan, France
| | - Jonathan R Lloyd
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Christopher Boothman
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Gareth T W Law
- Radiochemistry Unit, Department of Chemistry, The University of Helsinki, Helsinki 00014, Finland
| | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Joe S Small
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K
- National Nuclear Laboratory, Risley, Warrington, Cheshire WA3 6AE, U.K
| | - Gianni F Vettese
- Radiochemistry Unit, Department of Chemistry, The University of Helsinki, Helsinki 00014, Finland
| | - Heather A Williams
- Department of Nuclear Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, U.K
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K
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Grigaliūnienė D, Poškas R, Kilda R, Jouhara H, Poškas P. Modeling radionuclide migration from activated metallic waste disposal in a generic geological repository in Lithuania. NUCLEAR ENGINEERING AND DESIGN 2020. [DOI: 10.1016/j.nucengdes.2020.110885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Ruiz-Fresneda MA, Gomez-Bolivar J, Delgado-Martin J, Abad-Ortega MDM, Guerra-Tschuschke I, Merroun ML. The Bioreduction of Selenite under Anaerobic and Alkaline Conditions Analogous to Those Expected for a Deep Geological Repository System. Molecules 2019; 24:molecules24213868. [PMID: 31717840 PMCID: PMC6865132 DOI: 10.3390/molecules24213868] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 12/23/2022] Open
Abstract
The environmental conditions for the planned geological disposal of radioactive waste —including hyper-alkaline pH, radiation or anoxia—are expected to be extremely harsh for microbial activity. However, it is thought that microbial communities will develop in these repositories, and this would have implications for geodisposal integrity and the control of radionuclide migration through the surrounding environment. Nuclear waste contains radioactive isotopes of selenium (Se) such as 79Se, which has been identified as one of the main radionuclides in a geodisposal system. Here, we use the bacterial species Stenotrophomonas bentonitica, isolated from bentonites serving as an artificial barrier reference material in repositories, to study the reduction of selenite (SeIV) under simulated geodisposal conditions. This bacterium is able to reduce toxic SeIV anaerobically from a neutral to alkaline initial pH (up to pH 10), thereby producing elemental selenium (Se0) nanospheres and nanowires. A transformation process from amorphous Se (a-Se) nanospheres to trigonal Se (t-Se) nanowires, through the formation of monoclinic Se (m-Se) aggregates as an intermediate step, is proposed. The lesser solubility of Se0 and t-Se makes S. bentonitica a potential candidate to positively influence the security of a geodisposal system, most probably with lower efficiency rates than those obtained aerobically.
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Affiliation(s)
- Miguel Angel Ruiz-Fresneda
- Department of Microbiology, University of Granada, 18071 Granada, Spain; (J.G.-B.); (J.D.-M.); (M.L.M.)
- Correspondence:
| | - Jaime Gomez-Bolivar
- Department of Microbiology, University of Granada, 18071 Granada, Spain; (J.G.-B.); (J.D.-M.); (M.L.M.)
| | - Josemaria Delgado-Martin
- Department of Microbiology, University of Granada, 18071 Granada, Spain; (J.G.-B.); (J.D.-M.); (M.L.M.)
| | - Maria del Mar Abad-Ortega
- Centro de Instrumentación Científica (CIC), University of Granada, 18071 Granada, Spain; (M.d.M.A.-O.); (I.G.-T.)
| | - Isabel Guerra-Tschuschke
- Centro de Instrumentación Científica (CIC), University of Granada, 18071 Granada, Spain; (M.d.M.A.-O.); (I.G.-T.)
| | - Mohamed Larbi Merroun
- Department of Microbiology, University of Granada, 18071 Granada, Spain; (J.G.-B.); (J.D.-M.); (M.L.M.)
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