Strontium titanate synroc samples were synthesized by self-propagating high-temperature synthesis （SHS）. Sr directly took part in the synthesis process. As a result, the loading content issue is basically resolved. ...Strontium titanate synroc samples were synthesized by self-propagating high-temperature synthesis （SHS）. Sr directly took part in the synthesis process. As a result, the loading content issue is basically resolved. The products were characterized by density, microhardness X-ray diffraction, and scanning electron microscopy （SEM/EDS）. The leaching rate was measured by the method of PCT （product consistency test）. The results indicate that the Sr^2＋-SrTiO3 compound is of high density, low leach rate and high stability and the synthesis process is feasible in technology and economy. It can be concluded that the strontium titanate synroc is a perfect material to immobilize HLW.展开更多
According to the preliminary concept of the high-level radioactive waste （HLW） repository in China, a large-scale mock-up facility, named China-Mock-Up was constructed in the laboratory of Beijing Research Institute...According to the preliminary concept of the high-level radioactive waste （HLW） repository in China, a large-scale mock-up facility, named China-Mock-Up was constructed in the laboratory of Beijing Research Institute of Uranium Geology （BRIUG）. A heater, which simulates a container of radioactive waste, is placed inside the compacted Gaomiaozi （GMZ）-Na-bentonite blocks and pellets. Water inflow through the barrier from its outer surface is used to simulate the intake of groundwater. The numbers of water injection pipes, injection pressure and the insulation layer were determined based on the nu- merical modeling simulations. The current experimental data of the facility are herein analyzed. The experiment is intended to evaluate the thermo-hydro-mechano-chemical （THMC） processes occurring in the compacted bentonite-buffer during the early stage of HLW disposal and to provide a reliable database for numerical modeling and further investigation of engineered barrier system （EBS）, and the design of HLW repository.展开更多
As the multibarrier system has been adopted to dispose HLW glass in geological formation in many coun- tries, it was important to study the leaching behavior of vitrification under geological formation. This article d...As the multibarrier system has been adopted to dispose HLW glass in geological formation in many coun- tries, it was important to study the leaching behavior of vitrification under geological formation. This article describes the leaching behavior of simulated high level waste glass (90Nd/10), which can incorporate 16 wt.% simulated HLW in five kinds of geological media, such as granite, cement, bentonite, Fe3O4, etc. The durable experimental results show that the glass had less mass loss in granite and more mass loss in bentonite after a two-year leaching test. The SEM/XEDS analysis shows some element distributions on the leached specimen’s surface, i.e., Na, Si and Mg ele- ments were reduced on the specimen’s surface, whereas Ba, Al, and Fe were enriched on the specimen’s surface.展开更多
One of the most suitable ways under study for the disposal of high-level radioactive waste (HLW) is isolation in deep geological repositories. It is very important to research the thermo-hydro- mechanical (THM) coupl...One of the most suitable ways under study for the disposal of high-level radioactive waste (HLW) is isolation in deep geological repositories. It is very important to research the thermo-hydro- mechanical (THM) coupled processes associated with an HLW disposal repository. Non-linear coupled equations, which are used to describe the THM coupled process and are suited to saturated-unsaturated porous media, are presented in this paper. A numerical method to solve these equations is put forward, and a finite element code is developed. This code is suited to the plane strain or axis-symmetry problem. Then this code is used to simulate the THM coupled process in the near field of an ideal disposal repository. The temperature vs. time, hydraulic head vs. time and stress vs. time results show that, in this assumed condition, the impact of temperature is very long (over 10 000 a) and the impact of the water head is short (about 90 d). Since the stress is induced by temperature and hydraulic head in this condition, the impact time of stress is the same as that of temperature. The results show that THM coupled processes are very important in the safety analysis of an HLW deep geological disposal repository.展开更多
PHREEQC is a geochemical model to study aqueous ion reaction equilibrium in water systems. In this paper, PHREEQC was used to calculate concentrations of main elements (Si, Na, B, Al, Sr, Cs, Fe and Nd) leached from s...PHREEQC is a geochemical model to study aqueous ion reaction equilibrium in water systems. In this paper, PHREEQC was used to calculate concentrations of main elements (Si, Na, B, Al, Sr, Cs, Fe and Nd) leached from simulated HLW-glass in solution. The experiments were preformed in deionized-water or simulated underground water at 90℃ or 150℃ under low oxygen atmosphere. The calculated results agreed well with the experimental results.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No.20476008).
文摘Strontium titanate synroc samples were synthesized by self-propagating high-temperature synthesis （SHS）. Sr directly took part in the synthesis process. As a result, the loading content issue is basically resolved. The products were characterized by density, microhardness X-ray diffraction, and scanning electron microscopy （SEM/EDS）. The leaching rate was measured by the method of PCT （product consistency test）. The results indicate that the Sr^2＋-SrTiO3 compound is of high density, low leach rate and high stability and the synthesis process is feasible in technology and economy. It can be concluded that the strontium titanate synroc is a perfect material to immobilize HLW.
文摘According to the preliminary concept of the high-level radioactive waste （HLW） repository in China, a large-scale mock-up facility, named China-Mock-Up was constructed in the laboratory of Beijing Research Institute of Uranium Geology （BRIUG）. A heater, which simulates a container of radioactive waste, is placed inside the compacted Gaomiaozi （GMZ）-Na-bentonite blocks and pellets. Water inflow through the barrier from its outer surface is used to simulate the intake of groundwater. The numbers of water injection pipes, injection pressure and the insulation layer were determined based on the nu- merical modeling simulations. The current experimental data of the facility are herein analyzed. The experiment is intended to evaluate the thermo-hydro-mechano-chemical （THMC） processes occurring in the compacted bentonite-buffer during the early stage of HLW disposal and to provide a reliable database for numerical modeling and further investigation of engineered barrier system （EBS）, and the design of HLW repository.
文摘As the multibarrier system has been adopted to dispose HLW glass in geological formation in many coun- tries, it was important to study the leaching behavior of vitrification under geological formation. This article describes the leaching behavior of simulated high level waste glass (90Nd/10), which can incorporate 16 wt.% simulated HLW in five kinds of geological media, such as granite, cement, bentonite, Fe3O4, etc. The durable experimental results show that the glass had less mass loss in granite and more mass loss in bentonite after a two-year leaching test. The SEM/XEDS analysis shows some element distributions on the leached specimen’s surface, i.e., Na, Si and Mg ele- ments were reduced on the specimen’s surface, whereas Ba, Al, and Fe were enriched on the specimen’s surface.
文摘One of the most suitable ways under study for the disposal of high-level radioactive waste (HLW) is isolation in deep geological repositories. It is very important to research the thermo-hydro- mechanical (THM) coupled processes associated with an HLW disposal repository. Non-linear coupled equations, which are used to describe the THM coupled process and are suited to saturated-unsaturated porous media, are presented in this paper. A numerical method to solve these equations is put forward, and a finite element code is developed. This code is suited to the plane strain or axis-symmetry problem. Then this code is used to simulate the THM coupled process in the near field of an ideal disposal repository. The temperature vs. time, hydraulic head vs. time and stress vs. time results show that, in this assumed condition, the impact of temperature is very long (over 10 000 a) and the impact of the water head is short (about 90 d). Since the stress is induced by temperature and hydraulic head in this condition, the impact time of stress is the same as that of temperature. The results show that THM coupled processes are very important in the safety analysis of an HLW deep geological disposal repository.
文摘PHREEQC is a geochemical model to study aqueous ion reaction equilibrium in water systems. In this paper, PHREEQC was used to calculate concentrations of main elements (Si, Na, B, Al, Sr, Cs, Fe and Nd) leached from simulated HLW-glass in solution. The experiments were preformed in deionized-water or simulated underground water at 90℃ or 150℃ under low oxygen atmosphere. The calculated results agreed well with the experimental results.
