Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater
Tamusu claystone is one of the preselected host rocks for geological disposal of high-level radioactive waste in China. In this work, two claystone samples collected from borehole Tzk1 at the depth of 542 m(Tzk1-542) and borehole Tzk2 at the depth of 516 m (Tzk2-516) of Tamusu site in Inner Mongolia...
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| Format: | Article |
| Language: | zho |
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Editorial Office of Journal of Nuclear and Radiochemistry
2023-08-01
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| Series: | He huaxue yu fangshe huaxue |
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| Online Access: | http://www.jnrc.org.cn/CN/10.7538/hhx.2023.YX.2022029 |
| _version_ | 1797220461070778368 |
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| author | WU Jia-cheng KANG Ming-liang KANG Yi-xiao WU Han-yu LIN Qiao-ya SUN Le-wen ZHOU Fei |
| author_facet | WU Jia-cheng KANG Ming-liang KANG Yi-xiao WU Han-yu LIN Qiao-ya SUN Le-wen ZHOU Fei |
| author_sort | WU Jia-cheng |
| collection | DOAJ |
| description | Tamusu claystone is one of the preselected host rocks for geological disposal of high-level radioactive waste in China. In this work, two claystone samples collected from borehole Tzk1 at the depth of 542 m(Tzk1-542) and borehole Tzk2 at the depth of 516 m (Tzk2-516) of Tamusu site in Inner Mongolia were used to synthesize groundwater by soaking-balance method. The pH values of the synthetic groundwater were 9.45 and 8.24, respectively, and their components were analysed. Based on the Fe2+ and total Fe mass ratios of 78.36% and 91.92% in Tzk1-542 and Tzk2-516, the Eh values of -169.4 mV and 11.5 mV were proposed, respectively. In light of the obtained Eh, the solubility and speciation of U, 99Tc, 79Se and Np were calculated using PHREEQC with the latest OECD/NEA thermodynamic data and the thermodynamic data of uranyl carbonate complexes with Mg and Ca. When the pH range is 5.0-11.0 and the partial pressure of oxygen remains unchanged, the results show that the solubility of U, Se, Tc and Np in Tzk1-542 groundwater are 10-11-10-8, 10-16-10-9, 10-14-10-12 and 10-18-10-17 mol/L, respectively, while in Tzk2-516 groundwater they are 10-14-10-5, 10-14-10-5, 10-11-10-4 and 10-18-10-17 mol/L, respectively. The dissolved U, Se, Tc and Np in both groundwaters are mainly in the form of neutral molecules or anions. The claystone groundwater is generally under alkaline condition. When the pH is fixed(at 9.45 and 8.24 for Tzk1-542 and Tzk2-516, respectively) and the Eh varies from -169.4 mV to 169.4 mV, the solubility ranges of U, Se, Tc and Np in groundwater Tzk1-542 are 10-10-2.28×10-4, 10-12-10-3, 10-14-10-2 and 10-18-10-12 mol/L, respectively. The dissolved U, Se, Tc and Np mainly exist as negatively charged or neutral species such as UO2(CO3)4-3, CaUO2(CO3)2-3, SeO2-3, HSeO-3, TcO-4, NpO2OH, etc. For groundwater Tzk2-516, the solubility ranges of U, Se, Tc and Np are 10-11-10-5, 10-11-10-3, 10-16-10-2 and 10-19-10-13 mol/L, respectively. The dissolved U, Se, Tc and Np mainly exist as Ca2UO2(CO3)3, CaUO2(CO3)2-3, SeO2-3, HSeO-3, TcO-4, NpO2OH, etc. This work provides the simulation results of the homogeneous solution system. Further experimental works in combination with the real groundwaterwater condition for the related radionuclides are needed. |
| first_indexed | 2024-03-12T13:47:01Z |
| format | Article |
| id | doaj.art-5a375f7482004a31821ad13f99ddccd0 |
| institution | Directory Open Access Journal |
| issn | 0253-9950 |
| language | zho |
| last_indexed | 2024-04-24T12:49:54Z |
| publishDate | 2023-08-01 |
| publisher | Editorial Office of Journal of Nuclear and Radiochemistry |
| record_format | Article |
| series | He huaxue yu fangshe huaxue |
| spelling | doaj.art-5a375f7482004a31821ad13f99ddccd02024-04-06T05:48:46ZzhoEditorial Office of Journal of Nuclear and RadiochemistryHe huaxue yu fangshe huaxue0253-99502023-08-0145435336310.7538/hhx.2023.YX.2022029Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone GroundwaterWU Jia-cheng0KANG Ming-liang1KANG Yi-xiao2WU Han-yu3LIN Qiao-ya4SUN Le-wen5ZHOU Fei6Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversitySino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversitySino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversitySino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversitySino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversitySino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversitySino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen UniversityTamusu claystone is one of the preselected host rocks for geological disposal of high-level radioactive waste in China. In this work, two claystone samples collected from borehole Tzk1 at the depth of 542 m(Tzk1-542) and borehole Tzk2 at the depth of 516 m (Tzk2-516) of Tamusu site in Inner Mongolia were used to synthesize groundwater by soaking-balance method. The pH values of the synthetic groundwater were 9.45 and 8.24, respectively, and their components were analysed. Based on the Fe2+ and total Fe mass ratios of 78.36% and 91.92% in Tzk1-542 and Tzk2-516, the Eh values of -169.4 mV and 11.5 mV were proposed, respectively. In light of the obtained Eh, the solubility and speciation of U, 99Tc, 79Se and Np were calculated using PHREEQC with the latest OECD/NEA thermodynamic data and the thermodynamic data of uranyl carbonate complexes with Mg and Ca. When the pH range is 5.0-11.0 and the partial pressure of oxygen remains unchanged, the results show that the solubility of U, Se, Tc and Np in Tzk1-542 groundwater are 10-11-10-8, 10-16-10-9, 10-14-10-12 and 10-18-10-17 mol/L, respectively, while in Tzk2-516 groundwater they are 10-14-10-5, 10-14-10-5, 10-11-10-4 and 10-18-10-17 mol/L, respectively. The dissolved U, Se, Tc and Np in both groundwaters are mainly in the form of neutral molecules or anions. The claystone groundwater is generally under alkaline condition. When the pH is fixed(at 9.45 and 8.24 for Tzk1-542 and Tzk2-516, respectively) and the Eh varies from -169.4 mV to 169.4 mV, the solubility ranges of U, Se, Tc and Np in groundwater Tzk1-542 are 10-10-2.28×10-4, 10-12-10-3, 10-14-10-2 and 10-18-10-12 mol/L, respectively. The dissolved U, Se, Tc and Np mainly exist as negatively charged or neutral species such as UO2(CO3)4-3, CaUO2(CO3)2-3, SeO2-3, HSeO-3, TcO-4, NpO2OH, etc. For groundwater Tzk2-516, the solubility ranges of U, Se, Tc and Np are 10-11-10-5, 10-11-10-3, 10-16-10-2 and 10-19-10-13 mol/L, respectively. The dissolved U, Se, Tc and Np mainly exist as Ca2UO2(CO3)3, CaUO2(CO3)2-3, SeO2-3, HSeO-3, TcO-4, NpO2OH, etc. This work provides the simulation results of the homogeneous solution system. Further experimental works in combination with the real groundwaterwater condition for the related radionuclides are needed.http://www.jnrc.org.cn/CN/10.7538/hhx.2023.YX.2022029tamususynthetic groundwatervalence-variable radionuclidessolubilityspeciation |
| spellingShingle | WU Jia-cheng KANG Ming-liang KANG Yi-xiao WU Han-yu LIN Qiao-ya SUN Le-wen ZHOU Fei Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater He huaxue yu fangshe huaxue tamusu synthetic groundwater valence-variable radionuclides solubility speciation |
| title | Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater |
| title_full | Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater |
| title_fullStr | Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater |
| title_full_unstemmed | Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater |
| title_short | Investigation on Solubility and Speciation of Valence-Variable Radionuclides in Synthetic Tamusu Claystone Groundwater |
| title_sort | investigation on solubility and speciation of valence variable radionuclides in synthetic tamusu claystone groundwater |
| topic | tamusu synthetic groundwater valence-variable radionuclides solubility speciation |
| url | http://www.jnrc.org.cn/CN/10.7538/hhx.2023.YX.2022029 |
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