In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small to...In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small town named Tamusu,Western China.The study area is with complex surface conditions,thus the seismic exploration encountered a variettraveltimey of technical difculties such as crossing obstacles,de-noising harmful scattered waves,and building complex near-surface velocity models.In order to address those problems,techniques including cross-obstacle seismic geometry design,angle-domain harmful scattered noise removal,and an acoustic wave equation-based inversion method jointly utilizing both the and waveform of frst arrival waves were adopted.The fnal seismic images clearly exhibit the target rock’s unconformable contact boundary and its top interface beneath the sedimentary and weathered layers.On this basis,it could be confrmed that the target rock is not thin or has been transported by geological process from somewhere else,but a native and massive rock.There are a few small size fractures whose space distribution could be revealed by seismic images within the rock.The fractures should be kept away.Based on current research,it could be considered that active source seismic exploration is demanded during the sitting process of the geological disposal repository for nuclear waste.The seismic acquisition and processing techniques proposed in the present paper would ofer a good reference value for similar researches in the future.展开更多
The mechanical behavior of host rock for a deep geological repository of high-level radioactive waste plays a key role in ensuring the isolation function of host rock as a natural barrier under the multi-field couplin...The mechanical behavior of host rock for a deep geological repository of high-level radioactive waste plays a key role in ensuring the isolation function of host rock as a natural barrier under the multi-field coupling environment.For a better understanding of granite in China's Beishan pre-selected area for geological disposal of high-level radioactive waste,a series of investigations were carried out on in-situ stress field of rock mass at depth,strength and deformation characteristics of rocks under different stress and temperature conditions,and rock boreability and adaptability to Tunnel Boring Machine(TBM)technology.The results indicate that Beishan granite shows typical characteristics as a hard and brittle rock with a quite low permeability,and it is favorable to geological disposal.Meanwhile,a new rock mass suitability evaluation system was proposed,and the rock mass mainly composed of Beishan granite was proven to be suitable for geological disposal.Besides,the constructability of Beishan granite at engineering scale was tested and verified through field tests in the Beishan Exploration Tunnel(BET).Here,we summarize the main outcomes of rock mechanics research on Beishan granite in the past years and introduced the current progress of Beishan underground research laboratory(URL)for geological disposal.展开更多
In Japan,high-level radioactive waste and specific low-level radioactive waste which includes long-lived radionuclides are planned to be disposed of in the geological formations at depths greater than 300 m.The dispos...In Japan,high-level radioactive waste and specific low-level radioactive waste which includes long-lived radionuclides are planned to be disposed of in the geological formations at depths greater than 300 m.The disposal site will be selected through a stepwise site investigation process that consists of a Literature Survey,Preliminary Investigation,and Detailed Investigation phases.In October 2020 a Literature Survey was launched in Japan at two municipalities in Hokkaido for the first time since NUMO initiated a nationwide call for volunteer municipalities in 2002,and the outcomes are currently being compiled.To enhance the public’s understanding of how to implement safe geological disposal in Japan based on the latest scientific knowledge and technology,NUMO,as the implementing organisation,developed and published a safety case for geological disposal at the pre-siting stage.This safety case provides multiple lines of arguments and evidence to demonstrate the feasibility of the geological disposal and a basic structure for a safety case that will be applicable to any potential sites in Japan.The safety case also presented some R&D challenges to enhance the technical confidence of the project,including the R&D topics related to rock mechanics.This report presents the current status of the geological disposal programme in Japan,together with the status of the Literature Survey phase and an overview of the NUMO safety case.展开更多
Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fracture...Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fractured at 30° and 45° angles. The experimental results indicate that the steady creep strain rates of intact and fractured rock present an exponential increase trend with the increase of stress level. A nonlinear creep model is developed based on the experimental results, in which the initial damage caused by fracture together with the damage caused by constant load have been taken into consideration. The fitting analysis results indicated that the model proposed is more accurate at identifying the full creep regions in fractured granite, especially the accelerated stage of creep deformation. The least-square fit error of the proposed creep model is significantly lower than that of Nishihara model by almost an order of magnitude. An analysis of the effects of elastic modulus, viscosity coefficient, and damage factors on fractured rock strain rate and creep strain is conducted. If no consideration is given to the effects of the damage, the proposed nonlinear creep model can degenerate into to the classical Nishihara model.展开更多
In Slovakia, a direct disposal of spent nuclear fuel in a deep geological repository within the country after a certain period of interim storage is a preferred option. This paper briefly describes near field model of...In Slovakia, a direct disposal of spent nuclear fuel in a deep geological repository within the country after a certain period of interim storage is a preferred option. This paper briefly describes near field model of radionuclide migration developed in GoldSim simulation code environment and analyses the calculated results on time-dependent release rates of safety relevant radionuclides. Given the fact that GoldSimalso enables to perform probabilistic simulations using the Monte Carlo method, a probabilistic approach was chosen to assess the influence of selected near field parameter uncertainties related to radionuclide migration on the radionuclide release rates from the bentonite buffer to the surrounding host rock. Based on the results, release rates of nuclides which exceed their solubility limits are effectively lowered and many of nuclides are significantly sorbed on the buffer material. It can be seen that the variance of the total release rate in the case of solubility uncertainty is almost two orders of magnitude within a long period of time.展开更多
The corrosion behavior of NiCu low alloy steel and Q235 low carbon steel as the candidate materials for geological disposal containers of high-level radioactive waste in the simulated Beishan groundwater was comparati...The corrosion behavior of NiCu low alloy steel and Q235 low carbon steel as the candidate materials for geological disposal containers of high-level radioactive waste in the simulated Beishan groundwater was comparatively studied by weight loss test,electrochemical measurements,scanning electron microscope(SEM),electron probe microanalysis(EPMA),X-ray diffraction(XRD),Raman spectrum and X-ray photoelectron spectroscopy(XPS).The electrochemical results showed that the corrosion potential of NiCu steel and Q235 steel gradually increased with the immersion time.Simultaneously,the cathodic process transited from hydrogen evolution reaction(HER) control to the rust reduction control,while the anodic process was always dominated by the active dissolution of iron.By comparison,both the cathodic resistance and the anodic dissolution resistance of NiCu steel corrosion were apparently higher than that of Q235 steel.The results of rust layer characterization indicated that Ni and Cu elements could be enriched in the inner rust layer of NiCu steel and the rust layer was more compact.As the main corrosion products,the content of α-FeOOH in the rust layer of NiCu steel was obviously increased more than that of Q235 steel.Fe_(6)(OH)_(12)SO_(4)stably existed in the corrosion products of NiCu steel because Ni(Ⅱ) or Cu(Ⅱ)could substitute Fe(Ⅱ) of Fe_(6)(OH)_(12)SO_(4)and increased its oxidation resistance,Moreover,Ni and Cu could also make Fe3O4ionic selective by doping.After the long-term immersion,the corrosion mass loss of NiCu steel was significantly lower than Q235 steel,which further confirmed the benefits of Ni and Cu alloying on improving the steel corrosion resistance.展开更多
基金This research was supported by the National Key R&D Program of China(No.2018YFC1503200)the Nuclear Waste Geological Disposal Project([2013]727)+2 种基金the National Natural Science Foundation of China(Grant Nos.41790463 and 41730425)the Spark Program of Earthquake Sciences of CEA(XH18063Y)the Special Fund of GEC of CEA(YFGEC2017003,SFGEC2014006).
文摘In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body,two active source seismic profles were arranged near a small town named Tamusu,Western China.The study area is with complex surface conditions,thus the seismic exploration encountered a variettraveltimey of technical difculties such as crossing obstacles,de-noising harmful scattered waves,and building complex near-surface velocity models.In order to address those problems,techniques including cross-obstacle seismic geometry design,angle-domain harmful scattered noise removal,and an acoustic wave equation-based inversion method jointly utilizing both the and waveform of frst arrival waves were adopted.The fnal seismic images clearly exhibit the target rock’s unconformable contact boundary and its top interface beneath the sedimentary and weathered layers.On this basis,it could be confrmed that the target rock is not thin or has been transported by geological process from somewhere else,but a native and massive rock.There are a few small size fractures whose space distribution could be revealed by seismic images within the rock.The fractures should be kept away.Based on current research,it could be considered that active source seismic exploration is demanded during the sitting process of the geological disposal repository for nuclear waste.The seismic acquisition and processing techniques proposed in the present paper would ofer a good reference value for similar researches in the future.
基金supported by the China Atomic Energy Authority(CAEA)through the Geological Disposal Program and the National Natural Science Foundation of China(Grant No.11972149).
文摘The mechanical behavior of host rock for a deep geological repository of high-level radioactive waste plays a key role in ensuring the isolation function of host rock as a natural barrier under the multi-field coupling environment.For a better understanding of granite in China's Beishan pre-selected area for geological disposal of high-level radioactive waste,a series of investigations were carried out on in-situ stress field of rock mass at depth,strength and deformation characteristics of rocks under different stress and temperature conditions,and rock boreability and adaptability to Tunnel Boring Machine(TBM)technology.The results indicate that Beishan granite shows typical characteristics as a hard and brittle rock with a quite low permeability,and it is favorable to geological disposal.Meanwhile,a new rock mass suitability evaluation system was proposed,and the rock mass mainly composed of Beishan granite was proven to be suitable for geological disposal.Besides,the constructability of Beishan granite at engineering scale was tested and verified through field tests in the Beishan Exploration Tunnel(BET).Here,we summarize the main outcomes of rock mechanics research on Beishan granite in the past years and introduced the current progress of Beishan underground research laboratory(URL)for geological disposal.
文摘In Japan,high-level radioactive waste and specific low-level radioactive waste which includes long-lived radionuclides are planned to be disposed of in the geological formations at depths greater than 300 m.The disposal site will be selected through a stepwise site investigation process that consists of a Literature Survey,Preliminary Investigation,and Detailed Investigation phases.In October 2020 a Literature Survey was launched in Japan at two municipalities in Hokkaido for the first time since NUMO initiated a nationwide call for volunteer municipalities in 2002,and the outcomes are currently being compiled.To enhance the public’s understanding of how to implement safe geological disposal in Japan based on the latest scientific knowledge and technology,NUMO,as the implementing organisation,developed and published a safety case for geological disposal at the pre-siting stage.This safety case provides multiple lines of arguments and evidence to demonstrate the feasibility of the geological disposal and a basic structure for a safety case that will be applicable to any potential sites in Japan.The safety case also presented some R&D challenges to enhance the technical confidence of the project,including the R&D topics related to rock mechanics.This report presents the current status of the geological disposal programme in Japan,together with the status of the Literature Survey phase and an overview of the NUMO safety case.
基金supported by the National Natural Science Foundation of China(No.42307258)the technological research projects in Sichuan Province(No.2022YFSY0007)the China Atomic Energy Authority(CAEA)through the Geological Disposal Program.
文摘Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fractured at 30° and 45° angles. The experimental results indicate that the steady creep strain rates of intact and fractured rock present an exponential increase trend with the increase of stress level. A nonlinear creep model is developed based on the experimental results, in which the initial damage caused by fracture together with the damage caused by constant load have been taken into consideration. The fitting analysis results indicated that the model proposed is more accurate at identifying the full creep regions in fractured granite, especially the accelerated stage of creep deformation. The least-square fit error of the proposed creep model is significantly lower than that of Nishihara model by almost an order of magnitude. An analysis of the effects of elastic modulus, viscosity coefficient, and damage factors on fractured rock strain rate and creep strain is conducted. If no consideration is given to the effects of the damage, the proposed nonlinear creep model can degenerate into to the classical Nishihara model.
文摘In Slovakia, a direct disposal of spent nuclear fuel in a deep geological repository within the country after a certain period of interim storage is a preferred option. This paper briefly describes near field model of radionuclide migration developed in GoldSim simulation code environment and analyses the calculated results on time-dependent release rates of safety relevant radionuclides. Given the fact that GoldSimalso enables to perform probabilistic simulations using the Monte Carlo method, a probabilistic approach was chosen to assess the influence of selected near field parameter uncertainties related to radionuclide migration on the radionuclide release rates from the bentonite buffer to the surrounding host rock. Based on the results, release rates of nuclides which exceed their solubility limits are effectively lowered and many of nuclides are significantly sorbed on the buffer material. It can be seen that the variance of the total release rate in the case of solubility uncertainty is almost two orders of magnitude within a long period of time.
基金supported by the National Natural Science Foundation of China (Nos.U1867216,52173304 and 51701222)。
文摘The corrosion behavior of NiCu low alloy steel and Q235 low carbon steel as the candidate materials for geological disposal containers of high-level radioactive waste in the simulated Beishan groundwater was comparatively studied by weight loss test,electrochemical measurements,scanning electron microscope(SEM),electron probe microanalysis(EPMA),X-ray diffraction(XRD),Raman spectrum and X-ray photoelectron spectroscopy(XPS).The electrochemical results showed that the corrosion potential of NiCu steel and Q235 steel gradually increased with the immersion time.Simultaneously,the cathodic process transited from hydrogen evolution reaction(HER) control to the rust reduction control,while the anodic process was always dominated by the active dissolution of iron.By comparison,both the cathodic resistance and the anodic dissolution resistance of NiCu steel corrosion were apparently higher than that of Q235 steel.The results of rust layer characterization indicated that Ni and Cu elements could be enriched in the inner rust layer of NiCu steel and the rust layer was more compact.As the main corrosion products,the content of α-FeOOH in the rust layer of NiCu steel was obviously increased more than that of Q235 steel.Fe_(6)(OH)_(12)SO_(4)stably existed in the corrosion products of NiCu steel because Ni(Ⅱ) or Cu(Ⅱ)could substitute Fe(Ⅱ) of Fe_(6)(OH)_(12)SO_(4)and increased its oxidation resistance,Moreover,Ni and Cu could also make Fe3O4ionic selective by doping.After the long-term immersion,the corrosion mass loss of NiCu steel was significantly lower than Q235 steel,which further confirmed the benefits of Ni and Cu alloying on improving the steel corrosion resistance.
