Biogeochemical changes at early stage after the closure of radioactive waste geological repository in South Korea

Choung, Sungwook; Um, Wooyong; Choi, Seho; Francis, A.J.; Kim, Sungpyo; Park, Jin beak; Kim, Suk-Hoon

doi:10.1016/j.anucene.2014.03.021

Cited by 8 publications

(2 citation statements)

References 8 publications

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“…Nuclear power plant operators should dispose of low-level waste in shallow facilities (50 m or less below ground surface), while intermediate-level waste merits more stringent isolation and should be disposed of in deep (often 400–600 m) geological repositories (DGRs) (International Atomic Energy Agency, 2009). Six countries are currently containing and isolating mixed LILW in DGRs to protect the public and the environment until the radioactivity of the waste decays to background levels (Aikas and Anttila, 2008; Brewitz et al, 2008; Olsson et al, 2008; Powers and Holt, 2008; Woller, 2008; Choung et al, 2014). In several instances, cement backfill is added to provide additional isolation of the waste (Aikas and Anttila, 2008; Olsson et al, 2008), which creates hyper alkaline conditions in the repository.…”

Section: Introductionmentioning

confidence: 99%

Microbial Degradation of Cellulosic Material and Gas Generation: Implications for the Management of Low- and Intermediate-Level Radioactive Waste

Beaton

Pelletier²,

Goulet

2019

Front. Microbiol.

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Deep geologic repositories (DGR) in Canada are designed to contain and isolate low- and intermediate-level radioactive waste. Microbial degradation of the waste potentially produces methane, carbon dioxide and hydrogen gas. The generation of these gases increase rock cavity pressure and limit water ingress which delays the mobility of water soluble radionuclides. The objective of this study was to measure gas pressure and composition over 7 years in experiments containing cellulosic material with various starting conditions relevant to a DGR and to identify micro-organisms generating gas. For this purpose, we conducted experiments in glass bottles containing (1) wet cellulosic material, (2) wet cellulosic material with compost Maker, and (3) wet cellulosic material with compost Accelerator. Results demonstrated that compost accelerated the pressure build-up in the containers and that methane gas was produced in one experiment with compost and one experiment without compost because the pH remained neutral for the duration of the 464 days experiment. Methane was not formed in the other experiment because the pH became acidic. Once the pressure became similar in all containers after 464 days, we then monitored gas pressure and composition in glass bottle containing wet cellulosic material in (1) acidic conditions, (2) neutral conditions, and (3) with an enzyme that accelerated degradation of cellulose over 1965 days. In these experiments, acetogenic bacteria degraded cellulose and produced acetic acid, which acidity suppressed methane production. Microbial community analyses suggested a diverse community of archaea, bacteria and fungi actively degrading cellulose. DNA analyses also confirmed the presence of methanogens and acetogens in our experiments. This study suggests that methane gas will be generated in DGRs if pH remains neutral. However, our results showed that microbial degradation of cellulose not only generated gas, but also generated acidity. This finding is important as acids can limit bentonite swelling and potentially degrade cement and rock barriers, thus this requires consideration in the safety case as appropriate.

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Section: Introductionmentioning

confidence: 99%

Microbial Degradation of Cellulosic Material and Gas Generation: Implications for the Management of Low- and Intermediate-Level Radioactive Waste

Beaton

Pelletier²,

Goulet

2019

Front. Microbiol.

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“…The impact of microbial activity on the performance of a GDF has received considerable international attention [ 8 – 11 ]. Biogeochemical evolution [ 12 – 14 ], gas generation [ 12 , 15 – 17 ], complexation [ 3 , 18 ] and the fate of carbon-14 bearing wastes [ 19 , 20 ] are important issues. Within the ILW disposal area of a GDF, corrosion derived hydrogen [ 15 ] and cellulosic materials represent the dominant electron donors [ 11 ] available to drive these microbially mediated processes.…”

Section: Introductionmentioning

confidence: 99%

Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities

et al. 2015

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One design concept for the long-term management of the UK’s intermediate level radioactive wastes (ILW) is disposal to a cementitious geological disposal facility (GDF). Under the alkaline (10.013.0) anoxic conditions expected within a GDF, cellulosic wastes will undergo chemical hydrolysis. The resulting cellulose degradation products (CDP) are dominated by α- and β-isosaccharinic acids (ISA), which present an organic carbon source that may enable subsequent microbial colonisation of a GDF. Microcosms established from neutral, near-surface sediments demonstrated complete ISA degradation under methanogenic conditions up to pH 10.0. Degradation decreased as pH increased, with β-ISA fermentation more heavily influenced than α-ISA. This reduction in degradation rate was accompanied by a shift in microbial population away from organisms related to Clostridium sporosphaeroides to a more diverse Clostridial community. The increase in pH to 10.0 saw an increase in detection of Alcaligenes aquatilis and a dominance of hydrogenotrophic methanogens within the Archaeal population. Methane was generated up to pH 10.0 with acetate accumulation at higher pH values reflecting a reduced detection of acetoclastic methanogens. An increase in pH to 11.0 resulted in the accumulation of ISA, the absence of methanogenesis and the loss of biomass from the system. This study is the first to demonstrate methanogenesis from ISA by near surface microbial communities not previously exposed to these compounds up to and including pH 10.0.

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Archeological analogs for the lifetime prediction of the canister for spent nuclear fuel in the deep geological repository: Part II. Evolution of the corrosion rate over time

Mukhtar,

Bureš,

Lhotka

et al. 2024

Materials & Corrosion

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This work focused on evaluating the evolution of the corrosion product layer and associated corrosion rates on archeological artifacts from 16 sites. Sites with clay soils and maximum waterlogging (pond bottoms and wetlands) were monitored. The corrosion products were evaluated by X‐ray imaging, X‐ray diffraction, scanning electron microscope, Brunauer–Emmett–Teller, and nanoindentation. Two stages of corrosion attack with slightly different mechanisms were observed. Corrosion rates observed at sites with continuous flooding show average corrosion rates of 0.4–1 μm.a−1. These values demonstrate a minimum service life of the container outer case of 15 × 103 years, which is several times longer than the required lifetime of the outer case.

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Biogeochemical changes at early stage after the closure of radioactive waste geological repository in South Korea

Cited by 8 publications

References 8 publications

Microbial Degradation of Cellulosic Material and Gas Generation: Implications for the Management of Low- and Intermediate-Level Radioactive Waste

Microbial Degradation of Cellulosic Material and Gas Generation: Implications for the Management of Low- and Intermediate-Level Radioactive Waste

Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities

Archeological analogs for the lifetime prediction of the canister for spent nuclear fuel in the deep geological repository: Part II. Evolution of the corrosion rate over time

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