1
|
Maskalchuk LN, Baklai AA, Leont’eva TG, Makovskaya NA. Removal of Cesium Radionuclides from Aqueous Media with an Aluminosilicate Sorbent Prepared from Belaruskalii Production Waste. RADIOCHEMISTRY 2019. [DOI: 10.1134/s106636221904009x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
2
|
Joseph C, Mibus J, Trepte P, Müller C, Brendler V, Park DM, Jiao Y, Kersting AB, Zavarin M. Long-term diffusion of U(VI) in bentonite: Dependence on density. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 575:207-218. [PMID: 27741456 DOI: 10.1016/j.scitotenv.2016.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 09/28/2016] [Accepted: 10/02/2016] [Indexed: 06/06/2023]
Abstract
As a contribution to the safety assessment of nuclear waste repositories, U(VI) diffusion through the potential buffer material MX-80 bentonite was investigated at three clay dry densities over six years. Synthetic MX-80 model pore water was used as background electrolyte. Speciation calculations showed that Ca2UO2(CO3)3(aq) was the main U(VI) species. The in- and out-diffusion of U(VI) was investigated separately. U(VI) diffused about 3mm, 1.5mm, and 1mm into the clay plug at ρ=1.3, 1.6, and 1.9g/cm3, respectively. No through-diffusion of the U(VI) tracer was observed. However, leaching of natural uranium contained in the clay occurred and uranium was detected in all receiving reservoirs. As expected, the effective and apparent diffusion coefficients, De and Da, decreased with increasing dry density. The Da values for the out-diffusion of natural U(VI) were in good agreement with previously determined values. Surprisingly, Da values for the in-diffusion of U(VI) were about two orders of magnitude lower than values obtained in short-term in-diffusion experiments reported in the literature. Some potential reasons for this behavior that were evaluated are changes of the U(VI) speciation within the clay (precipitation, reduction) or changes of the clay porosity and pore connectivity with time. By applying Archie's law and the extended Archie's law, it was estimated that a significantly smaller effective porosity must be present for the long-term in-diffusion of U(VI). The results suggest that long-term studies of key transport phenomena may reveal additional processes that can directly impact long-term repository safety assessments.
Collapse
Affiliation(s)
- Claudia Joseph
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, CA 94550, USA.
| | - Jens Mibus
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, P.O. Box 510119, 01314 Dresden, Germany
| | - Paul Trepte
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, P.O. Box 510119, 01314 Dresden, Germany
| | - Christa Müller
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, P.O. Box 510119, 01314 Dresden, Germany
| | - Vinzenz Brendler
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, P.O. Box 510119, 01314 Dresden, Germany
| | - Dan M Park
- Biosciences and Biotechnology Division, Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, CA 94550, USA
| | - Yongqin Jiao
- Biosciences and Biotechnology Division, Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, CA 94550, USA
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, CA 94550, USA
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, CA 94550, USA
| |
Collapse
|
3
|
Tachi Y, Yotsuji K, Suyama T, Ochs M. Integrated sorption and diffusion model for bentonite. Part 2: porewater chemistry, sorption and diffusion modeling in compacted systems. J NUCL SCI TECHNOL 2014. [DOI: 10.1080/00223131.2014.914453] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
4
|
Fröhlich DR, Amayri S, Drebert J, Reich T. Influence of humic acid on neptunium(V) sorption and diffusion in Opalinus Clay. RADIOCHIM ACTA 2013. [DOI: 10.1524/ract.2013.2059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SummaryThe influence of14C-labeled M42 humic acid (HA) on the interaction between neptunium(V) and natural clay rock (Opalinus Clay (OPA), Switzerland) has been investigated in batch sorption and diffusion experiments under ambient air conditions. The effect of 10 mg/L HA on the diffusion of 8 μM Np(V) in OPA has been investigated in synthetic OPA pore water (pH 7.6, I = 0.4M) for the first time. Batch sorption experiments as a function of solid-to-liquid ratio (4-20 g/L) were performed under same experimental conditions to compare distribution coefficients obtained from both diffusion and sorption experiments. These experiments showed only a slight influence of HA on Np(V) uptake by OPA in both cases and provided comparable distribution coefficients (presence of HA: Kd= 22-32 L/kg, absence of HA: Kd= 30-46 L/kg). As it is known that the interactions of humic substances with actinides depend on various experimental parameters, the effect of HA on Np(V) sorption on 15 g/L OPA was also investigated as a function of pH (6-10) and initial Np concentration (8 μM and 7 pM). A saturated calcite solution was used as a background electrolyte in this case to prevent any dissolution of calcite contained in OPA at low pH. The results showed that the presence of M42 HA increases Np(V) sorption at pH < 7 while lower sorption was obtained above pH 8. Higher sorption at acidic pH can be attributed to strong sorption of HA which increases the number of sorption sites, while sorption decreases at higher pH probably due to formation of soluble ternary neptunium humate carbonate species.
Collapse
Affiliation(s)
- D. R. Fröhlich
- Institue of Nuclear Chemistry, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - S. Amayri
- Institue of Nuclear Chemistry, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - J. Drebert
- Institue of Nuclear Chemistry, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - T. Reich
- Institue of Nuclear Chemistry, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| |
Collapse
|
6
|
Tachi Y, Nakazawa T, Ochs M, Yotsuji K, Suyama T, Seida Y, Yamada N, Yui M. Diffusion and sorption of neptunium(V) in compacted montmorillonite: effects of carbonate and salinity. ACTA ACUST UNITED AC 2010. [DOI: 10.1524/ract.2010.1772] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractDiffusion and sorption of radionuclides in compacted bentonite/montmorillonite are key processes in the safe geological disposal of radioactive waste. In this study, the effects of carbonate and salinity on neptunium(V) diffusion and sorption in compacted sodium montmorillonite were investigated by experimental and modeling approaches. Effective diffusion coefficients (De) and distribution coefficients (Kd) of237Np(V) in sodium montmorillonite compacted to a dry density of 800 kg m−3were measured under four chemical conditions with different salinities (0.05/0.5 M NaCl) and carbonate concentrations (0/0.01 M NaHCO3).Devalues for carbonate-free conditions were of the order of 10−10–10−11 m2s−1and decreased as salinity increased, and those for carbonate conditions were of the order of 10−11–10−12 m2s−1and showed the opposite dependence. Diffusion-derivedKdvalues for carbonate-free conditions were higher by one order of magnitude than those for carbonate conditions. Diffusion and sorption behaviors were interpreted based on mechanistic models by coupling thermodynamic aqueous speciation, thermodynamic sorption model (TSM) based on ion exchange, and surface complexation reactions, and a diffusion model based on electrical double layer (EDL) theory in homogeneous narrow pores. The model predicted the experimentally observed tendency ofDeandKdqualitatively, as a result of the following mechanisms; 1) the dominant aqueous species are NpO2+and NpO2CO3−for carbonate-free and carbonate conditions, respectively, 2) the effects of cation excess and anion exclusion result in opposite tendencies ofDefor salinity, 3) higher carbonate in solution inhibits sorption due to the formation of carbonate complexes.
Collapse
Affiliation(s)
| | - T. Nakazawa
- Mitsubishi Materials Cooperation, Ibaraki, 311-0102, Japan
| | | | - K. Yotsuji
- Japan Atomic Energy Agency, Geological Isolation Research and, Ibaraki, 319-1194, Japan
| | - T. Suyama
- Japan Atomic Energy Agency, Geological Isolation Research, Ibaraki, 319-1194, Japan
| | - Y. Seida
- Japan Atomic Energy Agency, Geological Isolation Research and, Ibaraki, 319-1194, Japan
| | | | - Mikazu Yui
- Japan Atomic Energy Agency, Geological Isolation Research and, Ibaraki, 311-1194, Japan
| |
Collapse
|
7
|
Wu T, Amayri S, Drebert J, Van Loon LR, Reich T. Neptuniumnn(V) sorption and diffusion in opalinus clay. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:6567-6571. [PMID: 19764218 DOI: 10.1021/es9008568] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The sorption and diffusion behavior of 8 x 10(-6) M Np(V) in Opalinus Clay (OPA) with synthetic pore water (pH 7.6) as mobile phase was studied under ambient conditions by batch and diffusion experiments, respectively. The Kd value determined by batch experiments with OPA suspensions is equal to 0.025 +/- 0.005 m3/kg. The diffusion-accessible porosity epsilon of intact OPA as determined by through- and out-diffusion experiments with tritiated water (HTO) is equal to 0.15 +/- 0.01. The diffusion coefficient De and the rock capacity factor alpha of 22Na+ in OPA were measured by through-, out-, and in-diffusion experiments and asserted the reliability of these diffusion techniques. For the diffusion of Np(V) in synthetic pore water, the capillary method gave Dw = (6.0 +/- 1.0) x 10(-10) m/s. Due to the strong sorption of Np(V) on CPA, the diffusion of Np(V) was investigated bythe in-diffusiontechnique.The diffusion parameters for Np(V) in OPA are De = (6.9 +/- 1.1) x 10(-12) m2/s and alpha = 243 +/- 4. This corresponds to Kd = 0.10 +/- 0.01 m3/kg for the sorption of Np(V) in intact OPA.
Collapse
Affiliation(s)
- Tao Wu
- Intitue of Nuclear Chemistry, Jhannes Gutenberg-Universität Mains, 55099 Mains, Germany.
| | | | | | | | | |
Collapse
|
9
|
Petrova MA, Flowers AG, Krip IM, Shimchuk TV, Petrushka IM. Sorption of Sr on clay minerals modified with ferrocyanides and hydroxides of transition metals. RADIOCHEMISTRY 2008. [DOI: 10.1134/s1066362208050123] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
10
|
Sabodina MN, Kalmykov SN, Artem’eva KA, Zakharova EV, Sapozhnikov YA. Behavior of Cs, Np(V), Pu(IV), and U(VI) in pore water of bentonite. RADIOCHEMISTRY 2006. [DOI: 10.1134/s1066362206050158] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|