The solubility of actinides in a cementitious near-field environment

Ewart, F.T.; Smith-Briggs, J.L.; Thomason, H. P.; Williams, Stephen J.

doi:10.1016/0956-053x(92)90051-j

Cited by 38 publications

(56 citation statements)

References 7 publications

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“…The structural parameters resemble those reported for uranophane (Ca(UO 2 ) 2 (SiO 3 OH) 2 ·5H 2 O). One can also remind that the operational solubility limits of U(VI) obtained in [5,31] were comparable to the uranophane solubility calculated from thermodynamic data determined by [32]. It can be supposed that inner-sphere complex formation of U(VI) onto C-S-H is the predominant uptake mechanism by adsorption in a first time.…”

Section: Behaviour Of Cationic Rn In Cement Pastes Suspensions Vs Dementioning

confidence: 60%

Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands

Pointeau¹,

Coreau²,

Reiller³

2008

Radiochimica Acta

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To cite this version:I. Pointeau, N. Coreau, Pascal E. Reiller. Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands. Radiochimica Acta, R Oldenbourg Verlag GMBH, 2008, 96 (6) .0), corresponding to the decalcification of the calcium silicate hydrate (C-S-H) phases. The behaviour of anionic RN seems to be correlated to the evolution of calcium concentration and is opposed to the evolution of sulphate concentration in solution which could have a competing effect. Comparison is done with the behaviour of caesium and uranium(VI), which is a cationic RN but has a major negative hydrolysed species at high pH. As awaited, the uranium(VI) behaviour is very different from purely anionic RN one in accord with spectroscopic analyses from literature works. The R d values have also been measured for the organic ligands isosaccharinate (ISA) and EDTA. The uptake of ISA can be important and competing effect with the sorption of SeO 3 2− has been evidenced in HCP suspensions as a function of the ISA concentration.

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Section: Behaviour Of Cationic Rn In Cement Pastes Suspensions Vs Dementioning

confidence: 60%

Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands

Pointeau¹,

Coreau²,

Reiller³

2008

Radiochimica Acta

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“…The agreement between the experimental measurements of Ewart et al (1992) and the concentrations calculated in our study is poor at pH values less than 11. As noted by Ewart et al (1992), modeling calculations for americium solubilities in this pHEh region are sensitive to the concentrations used for dissolved carbonate and the thermodynamic data selected for .…”

Section: --mentioning

confidence: 71%

“…As noted by Ewart et al (1992), modeling calculations for americium solubilities in this pHEh region are sensitive to the concentrations used for dissolved carbonate and the thermodynamic data selected for .…”

Section: --mentioning

confidence: 99%

“…Ewart et al (1986Ewart et al ( , 1992 experimentally determined the concentrations of dissolved americium resulting from the equilibration of cement-equilibrated waters that were oversaturated with dissolved Anrn. Values estimated from data reported graphically by Ewart et al (1992, Figure 6) are plotted as filled circles in Figure 4.1 for comparison to the values calculated in our study by computer modeling.…”

Section: Published Solubility Datamentioning

confidence: 99%

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Effects on radionuclide concentrations by cement/ground-water interactions in support of performance assessment of low-level radioactive waste disposal facilities

Krupka¹,

Serne²

1998

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C o p k r o f h b r t r y~m d r t n d v d r u n d h 8~m m r h t h . N R C~~r AbstractThe U.S. Nuclear Regulatory Commission (NRC) is developing a technical position document that provides guidance regarding the performance assessment of low-level radioactive waste (LLW) disposal facilities. This guidance includes considerations associated with the chemical environment of the vault disposal system and the effects this system may have on the release and mobility of radionuclides. Because the disposal system will contain cementitious materials as structural, waste form, andor bacld'ill materials, the geochemical properties of pore waters buffered by reactions with cement will be very different from those waters associated with the local soil and geology. This environment therefore needs to be considered within the source term calculations if credit is taken for solubility limits andor distribution coefficients for -dissolved radionuclide concentrqtions within disposal units. Geochemical modeling may be used to assess potential chemical conditions in concrete vault disposal units and associated effects on aqueous speciation, solubilities, and sorption of radionuclides that are released from the waste form.In support of NRC7s development of this technical position, two literature reviews were done on information related to the chemical environments associated with the interaction of water with cementitious materials. One review was conducted on methods and associated solid-phase assemblages used to model the composition of pore water resulting from reaction with cementitious materials used in a disposal vault. This literature review also included related information on experimental studies of cemendwater systems, natural analogue studies of cement and concrete, and radionuclide solubilities experimentally determined in cement pore fluids.Based on the results of .this review, geochemical modeling was used to demonstrate the calculation of conservative maximum concentrations for dissolved americium, neptunium, nickel, plutonium, radium, strontium, thorium, and uranium with respect to key geochemical input parameters for two ground-water environments associated with the disposal system. These environments include 1) a cement buffered system, wherein the leachate pH is controlled at values above 10 by the effective buffering capacity of the concrete; and 2) a ground-water buffered system, wherein the leachate pH and related solution parameters are dominated by the local ground-water system.Another literature review was completed on the available data for the sorption potential of selected LLW radionuclides onto "fresh" cement/concretewhere the expected pH of the cement pore waters will equal or exceed 10. The review included data for the radionuclides americium, inorganic carbon, chlorine, iodine, lanthanide elements, niobium, nickel, neptunium, plutonium, radium, strontium, technetium, thorium, and uranium. Based on information gleaned from the literature, a database was developed of preferred minimum distribution coeff...

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“…Allard et al (1984) added Np(V) to a variety of cements & measured solubility after 100 days of 4e-9 M. Solubility of Np(IV) is ~1e-8 M for pH 9.75 through pH 12.6 (3). Thus, according to Allard et al (1984) and Ewart et al (1992) solubility of Np is about the same in concrete whether it is in +4 or +5 state. Ra 5x 10 -5 10 -6 5x 10 -5 10 -6 5x 10 -5 10 -6 RaSO 4 is the controlling solid (1, 14).…”

Section: Conservativementioning

confidence: 99%

Geochemical Data Package for Performance Assessment Calculations Related to the Savannah River Site

Kaplan

2016

130

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The solubility of actinides in a cementitious near-field environment

Cited by 38 publications

References 7 publications

Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands

Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands

Effects on radionuclide concentrations by cement/ground-water interactions in support of performance assessment of low-level radioactive waste disposal facilities

Geochemical Data Package for Performance Assessment Calculations Related to the Savannah River Site

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