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Wu T.,Huzhou University | Li Q.-M.,Huzhou University | Li Q.-M.,East China Institute of Technology | Wang H.,Huzhou University | And 4 more authors.
He-Huaxue yu Fangshe Huaxue/Journal of Nuclear and Radiochemistry | Year: 2015

The abundant phosphate in a high level nuclear waste repository will influence the migration of radionuclides. Thus, the effect of phosphate on the diffusion behavior of Se(IV) in Gaomiaozi (GMZ) bentonite was investigated by through-diffusion method. The diffusion parameters like effective diffusion coefficient (De) and rock capacity factor (α) were determined by house-made code named Fitting for Diffusion Parameters. The De and α values were about (0.61-1.3)×10-11 m2/s and 0.16-0.58, respectively. It shows that the concentration of phosphate has insignificant effect on Se(IV) diffusion. Under acidic condition, both of De and α increased. The apparent diffusion coefficient (Da) value decreased because Se(IV) could be sorbed on the surface of bentonite. Since α was less than the total porosity, it could not be sorbed on bentonite. ©, 2015, Science Press. All right reserved. Source


Wu T.,Huzhou Teachers College | Yao J.,China Institute of Atomic Energy | Dai W.,China Institute of Atomic Energy | Dai W.,East China Institute of Technology | And 4 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2012

With the low permeability and high swelling property, Gaomiaozi (GMZ) bentonite is regarded as the favorable candidate backfilling material for a potential repository. The diffusion behaviors of HTO in GMZ bentonite were studied to obtain effective diffusion coefficient (D e) and accessible porosity (ε) by through-and out-diffusion experiments. A computer code named Fitting for diffusion coefficient (FDP) was used for the experimental data processing and theoretical modeling. The D e and ε values were (5.2-11.2) × 10 -11 m 2/s and 0.35-0.50 at dry density from 1,800 to 2,000 kg/m 3 values at 1,800 kg/m 3, respectively. The D e was a little higher than that of at 2,000 kg/m 3 , whereas the D e value at 1,600 kg/m 3 was significantly higher (approximately twice) than that of at 1,800 and 2,000 kg/m 3. It may be explained that the diffusion of HTO mainly occurred in the interlayer space for the highly compacted clay (dry density exceeding 1,300 kg/m 3). 1,800 and 2,000 kg/m 3 probably had similar interlayer space, whereas 1,600 kg/m 3 had more. Both D e and ε values decreased with increasing dry density. For and e could be compacted bentonite, the relationship of De and Dε described by Archie's law with exponent n = 4.5 ± 1.0. © 2012 Akadémiai Kiadó, Budapest, Hungary. Source


Zhang S.,China Institute of Atomic Energy | Ding Y.,China Institute of Atomic Energy | Gu Z.,China Institute of Atomic Energy | Wang X.,Peking University | And 7 more authors.
Chemistry Bulletin / Huaxue Tongbao | Year: 2014

Under the new situation of China's rapid development of nuclear energy, the development of new nuclear energy resources, spent fuel reprocessing, fuel cycle chemistry research on treatment and disposal of radioactive waste has become increasingly active. With the continuous development of science and technology, ion accelerators, reactors, various types of detectors and analytical equipments, and computer technology, the scope and results of nuclear chemistry and radiochemistry research continues to expand and increase, such as nuclear safety, environmental radiochemistry, radiation analytical chemistry, radiopharmaceuticals and labeled compounds. These researches for national defense construction, nuclear energy, nuclear technology have important supporting role. This article reviews the recent progress in these fields in China. Source


Wu T.,Huzhou Teachers College | Wang H.,Huzhou Teachers College | Wang H.,Xian University of Science and Technology | Zheng Q.,Huzhou Teachers College | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014

Polyaminopolycarboxylate EDTA with powerful metal-binding property, which often presents in low and intermediate-level waste, can enhance the radionuclide migration. The effect of EDTA on the diffusion behavior of 99TcO4 - and ReO4 - in Gaomiaozi (GMZ) bentonite was investigated by using through-diffusion method. For 99TcO4 - in present of EDTA, the D e values was (1.2 ± 0.1) × 10-11 m 2/s, which was 4 times higher than that in absent of EDTA. It can be explained that the complexation between 99TcO4 - and EDTA might be formed. By contrast, the D e values of ReO4 - remained unchanged in present or absent of EDTA, indicating that ReO4 - could not complex with EDTA. However, the diffusion of ReO4 - could be increased in present of EDTA, the D a value was found to be increased from 1.8 × 10-10 to 5.4 × 10-10 m2/s. It demonstrated that ReO4 - need more drastic conditions to form the Re(VII)-EDTA complexes than those used for 99TcO4 -. For both ReO4 - and 99TcO 4 -, the rock capacity factor α is less than the total porosity ε tot, indicating that they has little retention/sorption on the surface of bentonite. © 2013 Akadémiai Kiadó, Budapest, Hungary. Source


Li J.Y.,China Resources New Energy Group Co. | Dai W.,Huzhou Teachers College | Dai W.,China Institute of Atomic Energy | Dai W.,East China Institute of Technology | And 5 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2012

99Tc is an important radionuclides related to repository safety assessment. The mobility pertechnetate (TcO4 -) can be reduced to immobility technetium(IV) hydrous oxides (TcO2· nH2O) by Fe(II)-bearing minerals. In China, Gaomiaozi (GMZ) bentonite is regarded as the favorable candidate backfilling material for the HLW repository, which is contained some FeO. The diffusion behavior of 99Tc was investigated in GMZ bentonite by through- and out-diffusion methods. The effective diffusion coefficient (D e), the accessible porosity (εacc), apparent diffusion coefficient (D a) and distribution coefficient (K d) were decreased with the increasing of dry density. The D e values were (2.8 ± 0.2) × 10-11 m2/s and (3.5 ± 0.2) × 10 -12 m2/s at dry density of 1,600 and 1,800 kg/m 3, respectively. It was indicated that the dominating species was TcO4 - during the diffusion processing. While, out-diffusion results showed that part of TcO4 - may be reduced by Fe(II). The relationship of D e and εacc could be described by Archie's law with exponent n = 2.4 for 99Tc diffusion in GMZ bentonite. Furthermore, the relationship between D a and dry density (ρ) was exponential. © 2012 Akadémiai Kiadó, Budapest, Hungary. Source

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