Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical du...Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.展开更多
An important challenge in ensuring the long-term effectiveness of geological nuclear waste disposal is predicting the transportation of decay heat and gases released from nuclear waste canisters.In this study,thermo-h...An important challenge in ensuring the long-term effectiveness of geological nuclear waste disposal is predicting the transportation of decay heat and gases released from nuclear waste canisters.In this study,thermo-hydromechanical(THM)coupled simulations were conducted using the TOUGH + FLAC3D simulator to predict the THM behaviors of a generic nuclear waste repository over 100,000 years following closure.The designed engineered barrier system(EBS)consists of the waste canister,backfill,and concrete liner.The objective of this study is to evaluate the long-term performance of the repository in the presence of continued hydrogen(H_(2))and heat release around the canister.The simulation results show that thermal pressurization and gas accumulation significantly raise the pore pressure within the EBS and surrounding host rock,while the peak pore pressure is not likely to exceed the lithostatic stress so that there is no risk of widespread hydro-fracturing in the host rock.However,tension failure and fracturing can occur at the tunnel scale because of internal gas buildup.Meanwhile,the generated H_(2) continuously migrates outward and tends to accumulate in the concrete liner and excavation disturbed zone surrounding the tunnel because of lower capillary pressure.Nevertheless,the fluids that may contain radionuclides will not leach into the confining units over a 100,000-year time frame.Our analysis indicates that for the assumed disposal system in Opalinus Clay,the generated heat and gas can gradually be transported through the host rock without significantly disturbing the isolation characteristics of the repository.展开更多
The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment wassystematically studied.Electrochemical methods,including electrochemical impendence spectra,Mott–Scho...The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment wassystematically studied.Electrochemical methods,including electrochemical impendence spectra,Mott–Schottky technology,cyclicpolarization,and potentiostatic polarization,were employed to characterize the corrosion behavior of copper at different temperatures.Stereoscopic microscopy and scanning electron microscopy were used to examine the surface morphology,and X-ray photoelectronspectroscopy analysis was used to identify the composition of the passive film.The experimental results show that corrosionresistance of the passive film does not blindly decrease with the increase of temperature but increases at60°C owing to a compactouter layer;there is a potential for pitting corrosion,which decreases as the temperature increases.The main product of copper in ananaerobic aqueous sulfide solution is Cu2S but the content of CuS increases at higher temperatures.The whole passivation rangeshows p-type semiconductor characteristics and the magnitude of the acceptor density is1023cm-3,which increases with increasingtemperature.展开更多
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
Sustainable energy sources are an immediate need to cope with the imminent issue of climate change the world is facing today.In particular,the long-lasting miniatured power sources that can supply energy continually t...Sustainable energy sources are an immediate need to cope with the imminent issue of climate change the world is facing today.In particular,the long-lasting miniatured power sources that can supply energy continually to power handheld gadgets,sensors,electronic devices,unmanned airborne vehicles in space and extreme mining are some of the examples where this is an acute need.It is known from basic physics that radioactive materials decay over few years and some nuclear materials have their half-life until thousands of years.The past five decades of research have been spent harnessing the decay energy of the radioactive materials to develop batteries that can last until the radioactive reaction continues.Thus,an emergent opportunity of industrial symbiosis to make use of nuclear waste by using radioactive waste as raw material to develop bat-teries with long shelf life presents a great opportunity for sustainable energy resource development.However,the current canon of research on this topic is scarce.This perspective draws fresh discussions on the topic while highlighting future directions in this wealthy arena of research.Graphical abstract A long-lasting miniaturised nuclear battery utilising 14C radioactive isotope as fuel.展开更多
We reported a rapid synthesis of Sm^(3+)/Zr^(4+)co-doped Gd2Ti2O7 pyrochlore simulated nuclear wastes solidification by self-propagation plus quick pressing technique.With increment excess contents of Sm2O3 and ZrO2 f...We reported a rapid synthesis of Sm^(3+)/Zr^(4+)co-doped Gd2Ti2O7 pyrochlore simulated nuclear wastes solidification by self-propagation plus quick pressing technique.With increment excess contents of Sm2O3 and ZrO2 from 0 to 10wt%,the phase composition of the products is a mixed phase of pyrochlore structure and defective fluorite structure by X-ray diffraction(XRD)analysis and Raman spectrum.In addition,the SEM results demonstrate the fracture surface and microstructure of Gd2Ti2O7-based pyrochlore.The densified pyrochlore waste form exhibits high bulk density of 5.56 g·cm^(-3) and vickers hardness of 11.20±0.2 GPa.The leaching tests show that the elemental leaching rates of Gd,Sm,and Cu after 42 days are 1.92×10^(-4),1.51×10^(-4),and 3.90×10^(-3) g·m^(-2)·d^(-1),respectively.展开更多
A set of potential parameters for modeling zircon was obtained by atomistic simulation techniques and a reasonable structural model of zircon was established by fitting some important properties of zircon.Based on the...A set of potential parameters for modeling zircon was obtained by atomistic simulation techniques and a reasonable structural model of zircon was established by fitting some important properties of zircon.Based on the equilibrium configuration of zircon, authors calculated the formation energies of basic point defects and intrinsic disorders. The heats of solution of substituting Pu for Zr showed that there was an immiscible gap at the composition of (Pu75%-Zr25%, in mole fraction), which suggests that the amount of Pu substituting for Zr in zircon be≤50%.展开更多
A compressible nuclear waste disposal contamination in porous media. is modeled by a coupled system of partial differential equations. The approximation of this system using a finite element method for the brine, radi...A compressible nuclear waste disposal contamination in porous media. is modeled by a coupled system of partial differential equations. The approximation of this system using a finite element method for the brine, radionuclides, and heat combined with a mixed finite element method for the pressure and velocity are analyzed. Optimal order error estimates in H-1 and L-2 are derived. This paper improves upon previously derived estimates in two aspects. Firstly, the error analysis is given with no restriction on the diffusion tensors. That is, it has included the effects of molecular diffusion and dispersion. Secondly, the 'complete compressibility' case is considered.展开更多
A complex Sol-Gel process has been used for synthesis of silica glasses designed to contain high-level nuclear wastes. Cs, Sr, Co, and Nd (generically denoted Me) were used, the last as surrogate for actinides. Gels i...A complex Sol-Gel process has been used for synthesis of silica glasses designed to contain high-level nuclear wastes. Cs, Sr, Co, and Nd (generically denoted Me) were used, the last as surrogate for actinides. Gels in the form of powders and sintered compacts were prepared by hydrolysis and polycondensation of tetraethoxide/Me nitrate solutions, which contained ascorbic acid as a catalyst. Thermal treatment studies were conducted on the resulting gels. Transformation to final products was studied by thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. Preliminary testing of Me leaching was also completed in quiescent water. Only a single dense form was resistant to展开更多
USA nuclear waste management program has stalled due to its continued insistence upon using Yucca Mountain for its disposal of DOE （Department of Energy） and commercial power plants NSF （nuclear spent fuel）. Incre...USA nuclear waste management program has stalled due to its continued insistence upon using Yucca Mountain for its disposal of DOE （Department of Energy） and commercial power plants NSF （nuclear spent fuel）. Increased flexibility and significant changes in DOE program are proposed. They include a private waste company to manage it; the construction and operation of ICS （interim centralized storage） facilities for NSF; the search for an AGR （alternate geological repository）; the use of a different methodology involving key local and state participants; a new ＂as safe as practical＂ strategy with defined benefits to the involved locations and states. Assured removal of NSF from ICS and providing limited Price Anderson indemnity for the program will enhance its acceptance. Minimum politics, regular information meetings, compromises, good cost projections and meeting schedules will be necessary to increase the chances of the proposed nuclear waste management program.展开更多
As a kind of green and clean energy resource,nuclear energy has attracted extensive attention and utilization[1].Technetium-^(99)(^(99)Tc)is a byproduct of 235U,which exists extensively in the spent fuel and radioacti...As a kind of green and clean energy resource,nuclear energy has attracted extensive attention and utilization[1].Technetium-^(99)(^(99)Tc)is a byproduct of 235U,which exists extensively in the spent fuel and radioactive waste generated during nuclear energy production(about 6%)[2].The volatile 99Tc can escape during the vitrification process of nuclear waste,posing the risk of leakage[3].展开更多
In this paper the authors discuss the numerical simulation problem of threedimensional compressible contamination treatment from nuclear waste.The mathematical model is defined by an initial-boundary nonlinear convect...In this paper the authors discuss the numerical simulation problem of threedimensional compressible contamination treatment from nuclear waste.The mathematical model is defined by an initial-boundary nonlinear convection-diffusion system of four partial differential equations:a parabolic equation for the pressure,two convection-diffusion equations for the concentrations of brine and radionuclide and a heat conduction equation for the temperature.The pressure appears within the concentration equations and heat conduction equation,and the Darcy velocity controls the concentrations and the temperature.The pressure is solved by the conservative mixed volume element method,and the order of the accuracy is improved by the Darcy velocity.The concentration of brine and temperature are computed by the upwind mixed volume element method on a changing mesh,where the diffusion is discretized by a mixed volume element and the convection is treated by an upwind scheme.The composite method can solve the convection-dominated diffusion problems well because it eliminates numerical dispersion and nonphysical oscillation and has high order computational accuracy.The mixed volume element has the local conservation of mass and energy,and it can obtain the brine and temperature and their adjoint vector functions simultaneously.The conservation nature plays an important role in numerical simulation of underground fluid.The concentrations of radionuclide factors are solved by the method of upwind fractional step difference and the computational work is decreased by decomposing a three-dimensional problem into three successive one-dimensional problems and using the method of speedup.By the theory and technique of a priori estimates of differential equations,we derive an optimal order result in L^(2) norm.Numerical examples are given to show the effectiveness and practicability and the composite method is testified as a powerful tool to solve the well-known actual problem.展开更多
The fate of different trace elements and radio nuclides in the new ZWILAG nuclear waste treatment plant （Switzerland） has been modelled, in order to predict and check the transport behaviour of the volatile species ...The fate of different trace elements and radio nuclides in the new ZWILAG nuclear waste treatment plant （Switzerland） has been modelled, in order to predict and check the transport behaviour of the volatile species and their distribution in the plant. Calculations show that for active waste from medicine, industry, research （MIR waste） only Zn and Cs have stable gaseous species at 1200℃. The investigations confirm the efficiency of the examined flue gas cleaning system.展开更多
In this paper the authors discuss a numerical simulation problem of three-dimensional compressible contamination treatment from nuclear waste. The mathematical model, a nonlinear convection-diffusion system of four PD...In this paper the authors discuss a numerical simulation problem of three-dimensional compressible contamination treatment from nuclear waste. The mathematical model, a nonlinear convection-diffusion system of four PDEs, determines four major physical unknowns: the pressure, the concentrations of brine and radionuclide, and the temperature. The pressure is solved by a conservative mixed finite volume element method, and the computational accuracy is improved for Darcy velocity. Other unknowns are computed by a composite scheme of upwind approximation and mixed finite volume element. Numerical dispersion and nonphysical oscillation are eliminated, and the convection-dominated diffusion problems are solved well with high order computational accuracy. The mixed finite volume element is conservative locally, and get the objective functions and their adjoint vector functions simultaneously. The conservation nature is an important character in numerical simulation of underground fluid. Fractional step difference is introduced to solve the concentrations of radionuclide factors, and the computational work is shortened significantly by decomposing a three-dimensional problem into three successive one-dimensional problems. By the theory and technique of a priori estimates of differential equations, we derive an optimal order estimates in L2norm. Finally, numerical examples show the effectiveness and practicability for some actual problems.展开更多
High-level radioactive waste should be isolated from humans and society for over 100,000 years.Several factors should be considered for a geologically stable disposal site such as topography,faults,seismic activity,an...High-level radioactive waste should be isolated from humans and society for over 100,000 years.Several factors should be considered for a geologically stable disposal site such as topography,faults,seismic activity,and hydrological properties.Brittle structures within the bedrock,such as faults,act as potential flow pathways for radioactive isotopes as well as significantly influence bedrock stability in the context of future seismicity.However,studies on fault behavior and deformation in underground settings,which are key components for site characterization,are relatively scarce compared with those at the surface.This study was conducted within the KAERI Underground Research Tunnel(KURT),an experimental tunnel focused on comprehending the structural evolution and designing nuclear waste disposal sites.To conduct a comprehensive structural study aimed at reconstructing the structural evolution of the study area in space and time,a preliminary lineament analysis was conducted using a length-weighted lineament analysis.Furthermore,kinematic analysis was conducted based on a cross-cutting relationship to establish the deformation history and change of paleostress condition.We identified three distinct brittle deformation stages evolving from a strike-slip to an extensional regime associated with the change of the maximum horizontal stress from ENE–WSW through NW–SE to NNE–SSW.This study underscored that a detailed study combining remote sensing lineament analysis,field structural surveys,and paleostress analysis could integrate and improve previously proposed methods for the selection of deep geological repositories.展开更多
Disposal of spent nuclear fuel and long lived radioactive waste in deep clay geological formations is one of the promising options worldwide. In this concept of the geological disposal system, the host clay formation ...Disposal of spent nuclear fuel and long lived radioactive waste in deep clay geological formations is one of the promising options worldwide. In this concept of the geological disposal system, the host clay formation is considered as a principal barrier on which the fulfillment of key safety functions rests. Between 2006 and 2010, the European Commission project TIMODAZ, which gathered 15 partners from 8 countries, has investigated the coupled thermo-hydro-mechanical （THM） effects on clay formations for geological disposal of radioactive waste, and specific attention was paid to investigating the thermal effect on the evolution of the damaged zone （DZ）. Three types of potential host clay formations were investigated： the Boom Clay （Belgium）, the Opalinus Clay （Switzerland） and the Callovo-Oxfordian argillite （France）. Intensive experimental （laboratory and in situ in underground research laboratories） and numerical studies have been performed. Multi-scale approach was used in the course of the project. High degree of similarities between the failure modes, sealing process, stress paths, deformation, etc., observed in laboratories and in situ has been obtained, which increased the confidence in the applicability of laboratory test results and up-scaling perspective. The results of the laboratory and in situ tests obtained allowed the parameters for numerical models at various scales to be derived and provided the basis for the simplified performance assessment models that are used to assess the long-term safety of a repository. The good cooperation between the numerical modeler and experimenters has allowed an in-depth analysis of the experimental results and thus better understanding the underlying processes, and consequently increased the capabilities to model the THM effects in claystones. This paper presents the main achievements obtained by TIMODAZ project and shows how a European scientific community investigates a problem of concern in a collaborative way and how the obtained main results are applied to the performance assessment of a geological repository.展开更多
Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common features are the potential hazard associated wi...Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common features are the potential hazard associated with their radioactivity and the need to manage them in such a way as to protect the human environment. The geological disposal is regarded as the most reasonable and effective way to safely disposing high-level radioactive wastes in the world. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolating geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. It is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation properties, thermal conductivity, chemical buffering property, canister supporting property, and stress buffering property over a long period of time. Bentonite is selected as the main content of buffer material that can satisfy the above requirements. The Gaomiaozi deposit is selected as the candidate supplier for China＇s buffer material of high level radioactive waste repository. This paper presents the geological features of the GMZ deposit and basic properties of the GMZ Na-bentonite. It is a super-large deposit with a high content of montmorillonite （about 75 %）, and GMZ-1, which is Na-bentonite produced from GMZ deposit is selected as the reference material for China＇s buffer material study.展开更多
The objective of this study was to address the challenges associated with complex TRPO waste,by utiliz-ing a natural aluminosilicate material to produce glass-ceramic waste forms.When the simulated waste content was b...The objective of this study was to address the challenges associated with complex TRPO waste,by utiliz-ing a natural aluminosilicate material to produce glass-ceramic waste forms.When the simulated waste content was below 30 wt.%,glassy waste forms were successfully obtained.Ce and Fe played crucial roles in the formation of Si-O-Ce bonds and[FeO_(4)]-tetrahedra in the glass network,which effectively immo-bilized other waste elements.However,when the waste content exceeded 30 wt.%,the waste was incor-porated into feldspar,iron-manganese crystals,fluorite ceramic,and glass.This combination of ceramic and glass matrices synergistically immobilized the waste,resulting in excellent mechanical performance and chemical durability.The leaching rates of LR_(Ce)and LR_(Nd)were remarkably low around-10^(−6)to 10^(−7)g m^(−2)d^(−1),after 42 d.Furthermore,the study also investigated the role of multi-valence elements,such as Ce,Fe,and Mn,in the formation of iron-containing aluminosilicate glass-ceramics.The findings offer a novel approach to effectively immobilize complex nuclear waste.展开更多
During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures wit...During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation.The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system.Thus,it is of central importance to analyze the consequences of potential future earthquake(s)on the hydrogeological properties of a repository site for spent nuclear fuel disposal.Based on the detailed site characterization data of the repository site at Forsmark,Sweden,we conduct a three-dimensional(3D)seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code(3DEC).We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution.An earthquake with a magnitude of M_(w)=5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed,with the faulting dynamics controlled by a strength weakening law.We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects.We further diagnose the distribution of fracture hydro-mechanical properties(e.g.mechanical/hydraulic aperture,hydraulic transmissivity)before and after the earthquake in order to quantify earthquakeinduced hydraulic changes in the fracture network.It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault.Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks.展开更多
The treatment of anionic ^(99)TcO_(4)^(-)in the waste tank with high alkalinity is still very challenging.In this work,a new temperature-responsive alkaline aqueous biphasic system(ABS)based on(tri-n–butyl)-ntetradec...The treatment of anionic ^(99)TcO_(4)^(-)in the waste tank with high alkalinity is still very challenging.In this work,a new temperature-responsive alkaline aqueous biphasic system(ABS)based on(tri-n–butyl)-ntetradecyl phosphonium chloride(P_(44414)Cl)was developed to remove radioactive ^(99)TcO_(4)^(-).The phase transition mechanism was studied by cloud point titration,small-angel X-ray scattering,dynamic light scattering,and molecular dynamic simulations.As the Na OH concentration or temperature increased,the P_(44414)^(+)micelle could grow and aggregate.This micelle showed a particularly high affinity toward ReO_(4)^(-)/^(99)TcO_(4)^(-)compared to other competing anions and could directly extract more than 98.6%of ^(99)TcO_(4)^(-)from simulated radioactive tank waste supernatant.Furthermore,the loaded ^(99)TcO_(4)^(-)could be easily stripped by using concentrated nitric acid rather than metal salt-based reductants.This work clearly demonstrates that the alkaline ABS is a promising separation system for solving the technetium problem in the alkaline waste tank.展开更多
基金Funded by the Key Research and Development Projects of Anhui Province(No.2022a05020026)the Key Technologies R&D Program of CNBM(Nos.2021HX0809,2021HX1011)the Anhui Science and Technology Major Project(No.2021e03020009)。
文摘Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.
基金Funding was provided by the U.S.Department of Energy,Office of Nuclear Energy,Spent Fuel and Waste Disposition,under Contract Number DE-AC02-05CH11231 with Lawrence Berkeley National Laboratory(LBNL).
文摘An important challenge in ensuring the long-term effectiveness of geological nuclear waste disposal is predicting the transportation of decay heat and gases released from nuclear waste canisters.In this study,thermo-hydromechanical(THM)coupled simulations were conducted using the TOUGH + FLAC3D simulator to predict the THM behaviors of a generic nuclear waste repository over 100,000 years following closure.The designed engineered barrier system(EBS)consists of the waste canister,backfill,and concrete liner.The objective of this study is to evaluate the long-term performance of the repository in the presence of continued hydrogen(H_(2))and heat release around the canister.The simulation results show that thermal pressurization and gas accumulation significantly raise the pore pressure within the EBS and surrounding host rock,while the peak pore pressure is not likely to exceed the lithostatic stress so that there is no risk of widespread hydro-fracturing in the host rock.However,tension failure and fracturing can occur at the tunnel scale because of internal gas buildup.Meanwhile,the generated H_(2) continuously migrates outward and tends to accumulate in the concrete liner and excavation disturbed zone surrounding the tunnel because of lower capillary pressure.Nevertheless,the fluids that may contain radionuclides will not leach into the confining units over a 100,000-year time frame.Our analysis indicates that for the assumed disposal system in Opalinus Clay,the generated heat and gas can gradually be transported through the host rock without significantly disturbing the isolation characteristics of the repository.
基金Project(FRF-TP-14-011C1) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2014CB643300) supported by the National Basic Research Program of China
文摘The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment wassystematically studied.Electrochemical methods,including electrochemical impendence spectra,Mott–Schottky technology,cyclicpolarization,and potentiostatic polarization,were employed to characterize the corrosion behavior of copper at different temperatures.Stereoscopic microscopy and scanning electron microscopy were used to examine the surface morphology,and X-ray photoelectronspectroscopy analysis was used to identify the composition of the passive film.The experimental results show that corrosionresistance of the passive film does not blindly decrease with the increase of temperature but increases at60°C owing to a compactouter layer;there is a potential for pitting corrosion,which decreases as the temperature increases.The main product of copper in ananaerobic aqueous sulfide solution is Cu2S but the content of CuS increases at higher temperatures.The whole passivation rangeshows p-type semiconductor characteristics and the magnitude of the acceptor density is1023cm-3,which increases with increasingtemperature.
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support provided by the UKRI via Grants No.EP/S036180/1 and EP/T024607/1feasibility study awards to LSBU from the UKRI National Interdisciplinary Circular Economy Hub (EP/V029746/1)+2 种基金Transforming the Foundation Industries:a Network+ (EP/V026402/1)the Hubert Curien Partnership award 2022 from the British Council,Transforming the Partnership award from the Royal Academy of Engineering (TSP1332)the Newton Fellowship award from the Royal Society (NIF\R1\191571).
文摘Sustainable energy sources are an immediate need to cope with the imminent issue of climate change the world is facing today.In particular,the long-lasting miniatured power sources that can supply energy continually to power handheld gadgets,sensors,electronic devices,unmanned airborne vehicles in space and extreme mining are some of the examples where this is an acute need.It is known from basic physics that radioactive materials decay over few years and some nuclear materials have their half-life until thousands of years.The past five decades of research have been spent harnessing the decay energy of the radioactive materials to develop batteries that can last until the radioactive reaction continues.Thus,an emergent opportunity of industrial symbiosis to make use of nuclear waste by using radioactive waste as raw material to develop bat-teries with long shelf life presents a great opportunity for sustainable energy resource development.However,the current canon of research on this topic is scarce.This perspective draws fresh discussions on the topic while highlighting future directions in this wealthy arena of research.Graphical abstract A long-lasting miniaturised nuclear battery utilising 14C radioactive isotope as fuel.
基金Funded by the National Natural Science Foundation of China(No.51672228)the Project of State Key Laboratory of Environmentfriendly Energy Materials(Southwest University of Science and Technology,Nos.18fksy0214 and 20fksy11)+1 种基金the Postgraduate Innovation Fund Project by Southwest University of Science and Technology(No.19ycx0016)the Science Development Foundation of China Academy of Engineering Physics。
文摘We reported a rapid synthesis of Sm^(3+)/Zr^(4+)co-doped Gd2Ti2O7 pyrochlore simulated nuclear wastes solidification by self-propagation plus quick pressing technique.With increment excess contents of Sm2O3 and ZrO2 from 0 to 10wt%,the phase composition of the products is a mixed phase of pyrochlore structure and defective fluorite structure by X-ray diffraction(XRD)analysis and Raman spectrum.In addition,the SEM results demonstrate the fracture surface and microstructure of Gd2Ti2O7-based pyrochlore.The densified pyrochlore waste form exhibits high bulk density of 5.56 g·cm^(-3) and vickers hardness of 11.20±0.2 GPa.The leaching tests show that the elemental leaching rates of Gd,Sm,and Cu after 42 days are 1.92×10^(-4),1.51×10^(-4),and 3.90×10^(-3) g·m^(-2)·d^(-1),respectively.
文摘A set of potential parameters for modeling zircon was obtained by atomistic simulation techniques and a reasonable structural model of zircon was established by fitting some important properties of zircon.Based on the equilibrium configuration of zircon, authors calculated the formation energies of basic point defects and intrinsic disorders. The heats of solution of substituting Pu for Zr showed that there was an immiscible gap at the composition of (Pu75%-Zr25%, in mole fraction), which suggests that the amount of Pu substituting for Zr in zircon be≤50%.
文摘A compressible nuclear waste disposal contamination in porous media. is modeled by a coupled system of partial differential equations. The approximation of this system using a finite element method for the brine, radionuclides, and heat combined with a mixed finite element method for the pressure and velocity are analyzed. Optimal order error estimates in H-1 and L-2 are derived. This paper improves upon previously derived estimates in two aspects. Firstly, the error analysis is given with no restriction on the diffusion tensors. That is, it has included the effects of molecular diffusion and dispersion. Secondly, the 'complete compressibility' case is considered.
基金part of studies that will be contin-ued within Polish Governmental Project“Technology Supporting Development of Safe Nuclear Power,”Part“Development of Techniques and Technologies Supporting Management of Spent Nuclear Fuel and Radioactive Waste.”
文摘A complex Sol-Gel process has been used for synthesis of silica glasses designed to contain high-level nuclear wastes. Cs, Sr, Co, and Nd (generically denoted Me) were used, the last as surrogate for actinides. Gels in the form of powders and sintered compacts were prepared by hydrolysis and polycondensation of tetraethoxide/Me nitrate solutions, which contained ascorbic acid as a catalyst. Thermal treatment studies were conducted on the resulting gels. Transformation to final products was studied by thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. Preliminary testing of Me leaching was also completed in quiescent water. Only a single dense form was resistant to
文摘USA nuclear waste management program has stalled due to its continued insistence upon using Yucca Mountain for its disposal of DOE （Department of Energy） and commercial power plants NSF （nuclear spent fuel）. Increased flexibility and significant changes in DOE program are proposed. They include a private waste company to manage it; the construction and operation of ICS （interim centralized storage） facilities for NSF; the search for an AGR （alternate geological repository）; the use of a different methodology involving key local and state participants; a new ＂as safe as practical＂ strategy with defined benefits to the involved locations and states. Assured removal of NSF from ICS and providing limited Price Anderson indemnity for the program will enhance its acceptance. Minimum politics, regular information meetings, compromises, good cost projections and meeting schedules will be necessary to increase the chances of the proposed nuclear waste management program.
基金supported by the National Natural Science Foundation of China(22322603,U2167218 and 22276054)the Beijing Outstanding Young Scientist Program.
文摘As a kind of green and clean energy resource,nuclear energy has attracted extensive attention and utilization[1].Technetium-^(99)(^(99)Tc)is a byproduct of 235U,which exists extensively in the spent fuel and radioactive waste generated during nuclear energy production(about 6%)[2].The volatile 99Tc can escape during the vitrification process of nuclear waste,posing the risk of leakage[3].
基金The authors express their deep appreciation to Prof.J.Douglas Jr,Prof.R.E.Ewing,and Prof.L.S.Jiang for their many helpful suggestions in the series research on numerical simulation of energy sciences.Also,the project is supported by NSAF(Grant No.U1430101)Natural Science Foundation of Shandong Province(Grant No.ZR2016AM08)National Tackling Key Problems Program(Grant Nos.2011ZX05052,2011ZX05011-004,20050200069).
文摘In this paper the authors discuss the numerical simulation problem of threedimensional compressible contamination treatment from nuclear waste.The mathematical model is defined by an initial-boundary nonlinear convection-diffusion system of four partial differential equations:a parabolic equation for the pressure,two convection-diffusion equations for the concentrations of brine and radionuclide and a heat conduction equation for the temperature.The pressure appears within the concentration equations and heat conduction equation,and the Darcy velocity controls the concentrations and the temperature.The pressure is solved by the conservative mixed volume element method,and the order of the accuracy is improved by the Darcy velocity.The concentration of brine and temperature are computed by the upwind mixed volume element method on a changing mesh,where the diffusion is discretized by a mixed volume element and the convection is treated by an upwind scheme.The composite method can solve the convection-dominated diffusion problems well because it eliminates numerical dispersion and nonphysical oscillation and has high order computational accuracy.The mixed volume element has the local conservation of mass and energy,and it can obtain the brine and temperature and their adjoint vector functions simultaneously.The conservation nature plays an important role in numerical simulation of underground fluid.The concentrations of radionuclide factors are solved by the method of upwind fractional step difference and the computational work is decreased by decomposing a three-dimensional problem into three successive one-dimensional problems and using the method of speedup.By the theory and technique of a priori estimates of differential equations,we derive an optimal order result in L^(2) norm.Numerical examples are given to show the effectiveness and practicability and the composite method is testified as a powerful tool to solve the well-known actual problem.
文摘The fate of different trace elements and radio nuclides in the new ZWILAG nuclear waste treatment plant （Switzerland） has been modelled, in order to predict and check the transport behaviour of the volatile species and their distribution in the plant. Calculations show that for active waste from medicine, industry, research （MIR waste） only Zn and Cs have stable gaseous species at 1200℃. The investigations confirm the efficiency of the examined flue gas cleaning system.
基金supported by the Natural Science Foundation of Shangdong Province (Grant No.ZR2021MA019)Natural Science Foundation of Hunan Province (Grant No.2018JJ2028)。
文摘In this paper the authors discuss a numerical simulation problem of three-dimensional compressible contamination treatment from nuclear waste. The mathematical model, a nonlinear convection-diffusion system of four PDEs, determines four major physical unknowns: the pressure, the concentrations of brine and radionuclide, and the temperature. The pressure is solved by a conservative mixed finite volume element method, and the computational accuracy is improved for Darcy velocity. Other unknowns are computed by a composite scheme of upwind approximation and mixed finite volume element. Numerical dispersion and nonphysical oscillation are eliminated, and the convection-dominated diffusion problems are solved well with high order computational accuracy. The mixed finite volume element is conservative locally, and get the objective functions and their adjoint vector functions simultaneously. The conservation nature is an important character in numerical simulation of underground fluid. Fractional step difference is introduced to solve the concentrations of radionuclide factors, and the computational work is shortened significantly by decomposing a three-dimensional problem into three successive one-dimensional problems. By the theory and technique of a priori estimates of differential equations, we derive an optimal order estimates in L2norm. Finally, numerical examples show the effectiveness and practicability for some actual problems.
基金supported by the Institute for Korea Spent Nuclear Fuel(iKSNF)National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT,MSIT)(No.2021M2E1A1085200).
文摘High-level radioactive waste should be isolated from humans and society for over 100,000 years.Several factors should be considered for a geologically stable disposal site such as topography,faults,seismic activity,and hydrological properties.Brittle structures within the bedrock,such as faults,act as potential flow pathways for radioactive isotopes as well as significantly influence bedrock stability in the context of future seismicity.However,studies on fault behavior and deformation in underground settings,which are key components for site characterization,are relatively scarce compared with those at the surface.This study was conducted within the KAERI Underground Research Tunnel(KURT),an experimental tunnel focused on comprehending the structural evolution and designing nuclear waste disposal sites.To conduct a comprehensive structural study aimed at reconstructing the structural evolution of the study area in space and time,a preliminary lineament analysis was conducted using a length-weighted lineament analysis.Furthermore,kinematic analysis was conducted based on a cross-cutting relationship to establish the deformation history and change of paleostress condition.We identified three distinct brittle deformation stages evolving from a strike-slip to an extensional regime associated with the change of the maximum horizontal stress from ENE–WSW through NW–SE to NNE–SSW.This study underscored that a detailed study combining remote sensing lineament analysis,field structural surveys,and paleostress analysis could integrate and improve previously proposed methods for the selection of deep geological repositories.
基金funded by the European Commission through the TIMODAZ project within the 6th framework programme (Contract Number: FI6W-CT-2007-036449)
文摘Disposal of spent nuclear fuel and long lived radioactive waste in deep clay geological formations is one of the promising options worldwide. In this concept of the geological disposal system, the host clay formation is considered as a principal barrier on which the fulfillment of key safety functions rests. Between 2006 and 2010, the European Commission project TIMODAZ, which gathered 15 partners from 8 countries, has investigated the coupled thermo-hydro-mechanical （THM） effects on clay formations for geological disposal of radioactive waste, and specific attention was paid to investigating the thermal effect on the evolution of the damaged zone （DZ）. Three types of potential host clay formations were investigated： the Boom Clay （Belgium）, the Opalinus Clay （Switzerland） and the Callovo-Oxfordian argillite （France）. Intensive experimental （laboratory and in situ in underground research laboratories） and numerical studies have been performed. Multi-scale approach was used in the course of the project. High degree of similarities between the failure modes, sealing process, stress paths, deformation, etc., observed in laboratories and in situ has been obtained, which increased the confidence in the applicability of laboratory test results and up-scaling perspective. The results of the laboratory and in situ tests obtained allowed the parameters for numerical models at various scales to be derived and provided the basis for the simplified performance assessment models that are used to assess the long-term safety of a repository. The good cooperation between the numerical modeler and experimenters has allowed an in-depth analysis of the experimental results and thus better understanding the underlying processes, and consequently increased the capabilities to model the THM effects in claystones. This paper presents the main achievements obtained by TIMODAZ project and shows how a European scientific community investigates a problem of concern in a collaborative way and how the obtained main results are applied to the performance assessment of a geological repository.
文摘Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common features are the potential hazard associated with their radioactivity and the need to manage them in such a way as to protect the human environment. The geological disposal is regarded as the most reasonable and effective way to safely disposing high-level radioactive wastes in the world. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolating geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. It is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation properties, thermal conductivity, chemical buffering property, canister supporting property, and stress buffering property over a long period of time. Bentonite is selected as the main content of buffer material that can satisfy the above requirements. The Gaomiaozi deposit is selected as the candidate supplier for China＇s buffer material of high level radioactive waste repository. This paper presents the geological features of the GMZ deposit and basic properties of the GMZ Na-bentonite. It is a super-large deposit with a high content of montmorillonite （about 75 %）, and GMZ-1, which is Na-bentonite produced from GMZ deposit is selected as the reference material for China＇s buffer material study.
基金supported by the National Natural Science Foundation of China(Nos.21976146 and U2167221)the Project of State Key Laboratory of Environment-friendly Energy Materials,Southwest University of Science and Technology(No.23fksy10)+2 种基金the Open Foundation of Nuclear Medicine Laboratory of Mianyang Central Hospital(No.2021HYX028)the Sichuan Science and Technology Program(No.2023NSFSC0353)the Applied Basic Research Project of Science and Technology Department of Sichuan Province(No.2022NSFSC1197)。
文摘The objective of this study was to address the challenges associated with complex TRPO waste,by utiliz-ing a natural aluminosilicate material to produce glass-ceramic waste forms.When the simulated waste content was below 30 wt.%,glassy waste forms were successfully obtained.Ce and Fe played crucial roles in the formation of Si-O-Ce bonds and[FeO_(4)]-tetrahedra in the glass network,which effectively immo-bilized other waste elements.However,when the waste content exceeded 30 wt.%,the waste was incor-porated into feldspar,iron-manganese crystals,fluorite ceramic,and glass.This combination of ceramic and glass matrices synergistically immobilized the waste,resulting in excellent mechanical performance and chemical durability.The leaching rates of LR_(Ce)and LR_(Nd)were remarkably low around-10^(−6)to 10^(−7)g m^(−2)d^(−1),after 42 d.Furthermore,the study also investigated the role of multi-valence elements,such as Ce,Fe,and Mn,in the formation of iron-containing aluminosilicate glass-ceramics.The findings offer a novel approach to effectively immobilize complex nuclear waste.
文摘During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation.The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system.Thus,it is of central importance to analyze the consequences of potential future earthquake(s)on the hydrogeological properties of a repository site for spent nuclear fuel disposal.Based on the detailed site characterization data of the repository site at Forsmark,Sweden,we conduct a three-dimensional(3D)seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code(3DEC).We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution.An earthquake with a magnitude of M_(w)=5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed,with the faulting dynamics controlled by a strength weakening law.We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects.We further diagnose the distribution of fracture hydro-mechanical properties(e.g.mechanical/hydraulic aperture,hydraulic transmissivity)before and after the earthquake in order to quantify earthquakeinduced hydraulic changes in the fracture network.It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault.Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks.
基金supported by the National Natural Science Foundation of China(Nos.21876124,U2032106)Natural Science Foundation of Zhejiang Province(Nos.LR21B060001 and LQ21B070004)。
文摘The treatment of anionic ^(99)TcO_(4)^(-)in the waste tank with high alkalinity is still very challenging.In this work,a new temperature-responsive alkaline aqueous biphasic system(ABS)based on(tri-n–butyl)-ntetradecyl phosphonium chloride(P_(44414)Cl)was developed to remove radioactive ^(99)TcO_(4)^(-).The phase transition mechanism was studied by cloud point titration,small-angel X-ray scattering,dynamic light scattering,and molecular dynamic simulations.As the Na OH concentration or temperature increased,the P_(44414)^(+)micelle could grow and aggregate.This micelle showed a particularly high affinity toward ReO_(4)^(-)/^(99)TcO_(4)^(-)compared to other competing anions and could directly extract more than 98.6%of ^(99)TcO_(4)^(-)from simulated radioactive tank waste supernatant.Furthermore,the loaded ^(99)TcO_(4)^(-)could be easily stripped by using concentrated nitric acid rather than metal salt-based reductants.This work clearly demonstrates that the alkaline ABS is a promising separation system for solving the technetium problem in the alkaline waste tank.
