Neptunium, plutonium and 137Cs sorption by bentonite clays and their speciation in pore waters

Sabodina, M. N.; Kalmykov, Stepan N.; Sapozhnikov, Yu. A.; Zakharova, Еlena V.

doi:10.1007/s10967-006-0356-6

Cited by 38 publications

(22 citation statements)

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“…This was probably due to the slight decreases in EC (positively related to ionic strength) and Na concentration of the outflow from 259 ± 2 to 202 ± 2 μs cm −1 and from 0.94 ± 0.2 to 0.83 ± 0.2 mmol L −1 , respectively. Adsorption of Cs on montmorillonite‐rich bentonite, as well as on illite and kaolinite, has been reported to increase markedly with decreasing ionic strength as a result of the decreased availability of Na to compete with Cs for adsorption sites on the clays (Saiers and Hornberger, 1999; Sabodina et al, 2006; Turner et al, 2006). In this study, post‐switching increases in colloid‐associated Cs transport were more pronounced in the presence of HA in Exp.…”

Section: Resultsmentioning

confidence: 99%

Dissolved and Colloidal Transport of Cesium in Natural Discrete Fractures

Tang

Weisbrod

2010

J of Env Quality

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Transport of cesium (Cs) was investigated in a saturated natural chalk fracture with an average equivalent hydraulic aperture of 129 microm. The results show that Cs (inflow concentration of 0.22 mmol L(-1)) can be transported in its dissolved form and in association with montmorillonite. Humic acid (HA) did not sorb Cs but enhanced colloid-associated Cs transport by 12.5% in terms of breakthrough curve (BTC) recovery. The BTCs clearly showed desorption of Cs from the fracture walls during the artificial rainwater (ARW)-injection period. Cesium transport associated with montmorillonite colloids was significant, with a maximum colloid-associated Cs C/C(0) (outflow-to-inflow concentration ratio) value of 16.6 +/- 1.1% during the tracer (colloids and LiBr)-injection period. However, the relative contribution of colloid-associated Cs transport to total Cs transport was relatively low, amounting to 10.3 +/- 0.7% and 14.5 +/- 0.7% with montmorillonite (500 mg L(-1)) and the montmorillonite-HA (10 mg L(-1)) mixture, respectively. Readsorption of Cs onto the colloids occurred immediately on switching from the tracer suspension to the background solution of ARW. The significant colloid-associated Cs transport, the stripping effect of Cs from colloids, and the slow desorption of Cs from fracture walls reported in this study have important implications for risk assessments of Cs mobility in fractured carbonatic rocks.

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Section: Resultsmentioning

confidence: 99%

Dissolved and Colloidal Transport of Cesium in Natural Discrete Fractures

Tang

Weisbrod

2010

J of Env Quality

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“…For this to be successful, thermodynamic databases need to be expanded so that predictions of radionuclide sorption can be made over the range of conditions that may occur. (Houseworth 2010, Section 2.8;Sabodina et al 2006;Khan 2002;Donat et al 2005;Samper et al 2008).…”

Section: Knowledge Gapsmentioning

confidence: 99%

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Rutqvist¹,

Liu²,

Steefel³

et al. 2011

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Eric Sonnenthal (LBNL) Engineered Barrier System (EBS) Evaluation This page is intentionally left blank Engineered Barrier System (EBS) Evaluation 5 Executive SummaryKey components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate longterm repository performance.The focus of this report is the following:• Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept;• Evaluation of key parameters in the characterization of EBS performance;• Identification of key knowledge gaps and uncertainties;• Evaluation of tools and modeling approaches for EBS processes and performance.The above topics will be evaluated through the analysis of the following:• Overview of EBS concepts for various NW disposal systems;• Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments;• Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS;• Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems Evaluation Framework (DSEF).This report will focus on the multi-barrier concept of EBS and variants of this type which in essence is the most adopted concept by various repository programs. Empasis is given mainly to the evaluation of EBS materials and processes through the analysis of published studies in the scientific literature of past and existing repository research programs. Tool evaluations are also emphasized, particularly on THCM processes and chemical equilibria. Although being an increasingly important aspect of NW disposition, short-term or interim storage of NW will be briefly discussed but not to the extent of the EBS issues relevant to disposal systems in deep geologic environments. Interim storage will be discussed in the report Evaluation of Storage Concepts FY10 Final Report (Weiner et al. 2010). Engineered Barrier System (EBS) Evaluation 6This page is intentionally left blank Engineered Barrier System (EBS) Eva...

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“…Clays are known to sorb Pu Keeney-Kennicutt and Morse, 1985;Kozai et al, 1996;Kozai et al, 1993;Lujaniene et al, 2007;Powell et al, 2004Powell et al, , 2005Powell et al, 2008;Sabodina et al, 2006;Sanchez et al, 1985;Turner et al, 1998). In addition, the proposed use of bentonite within some engineered barrier systems scenarios for high-level nuclear waste repositories provides additional importance to understanding Pu interaction with smectite aluminosilicate clays (Sabodina et al, 2006). Smectite clay may represent a key phase that will control transport of Pu in repository near and far fields.…”

Section: Introductionmentioning

confidence: 99%