title: Modelling geochemical and microbial consumption of dissolved oxygen after backfilling a high level radiactive waste repository.
abstract: Dissolved oxygen (DO) left in the voids of buffer and backfill materials of a deep geological high level radioactive waste (HLW) repository could cause canister corrosion. Available data from laboratory and in situ experiments indicate that microbes play a substantial role in controlling redox conditions near a HLW repository. This paper presents the application of a coupled hydro-bio-geochemical model to evaluate geochemical and microbial consumption of DO in bentonite porewater after backfilling of a HLW repository designed according to the Swedish reference concept. In addition to geochemical reactions, the model accounts for dissolved organic carbon (DOC) respiration and methane oxidation. Parameters for microbial processes were derived from calibration of the REX in situ experiment carried out at the Aspö underground laboratory. The role of geochemical and microbial processes in consuming DO is evaluated for several scenarios. Numerical results show that both geochemical and microbial processes are relevant for DO consumption. However, the time needed to consume the DO trapped in the bentonite buffer decreases dramatically from several hundreds of years when only geochemical processes are considered to a few weeks when both geochemical reactions and microbially-mediated DOC respiration and methane oxidation are taken into account simultaneously.
authors.affiliation: E.T.S. de Ingenieros de Caminos, Canales y Puertos, Universidad de La Coruña, Campus de Elviña s/n. 15192 La Coruña, Spain.
authors.forename: Changbing
authors.initials: C
authors.lastname: Yang
authors.forename: Javier
authors.initials: J
authors.lastname: Samper
authors.forename: Jorge
authors.initials: J
authors.lastname: Molinero
authors.forename: Mercedes
authors.initials: M
authors.lastname: Bonilla
mesh_terms: D001546:Bentonite / Q000737:chemistry; D002138:Calibration; D002244:Carbon / Q000737:chemistry; D002621:Chemistry / Q000379:methods*; D002625:Chemistry, Organic / Q000379:methods; D004867:Equipment Design; D005844:Geology / Q000379:methods*; D008697:Methane / Q000737:chemistry; D008956:Models, Chemical; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism*; D010101:Oxygen Consumption; D011850:Radioactive Waste; D014871:Water Microbiology
chemical_list: D011850:Radioactive Waste; D001546:Bentonite; D002244:Carbon; D008697:Methane; D010100:Oxygen