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
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
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 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
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
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
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
There are costs for doing the right thing,but regret is not one of those costs.I learned this lesson the hard way throughout a 42-year engineering career.As a young engineer,raising a family,I was more adaptable to ma...There are costs for doing the right thing,but regret is not one of those costs.I learned this lesson the hard way throughout a 42-year engineering career.As a young engineer,raising a family,I was more adaptable to management mandates,i.e.,I was more willing to be unethical to keep my job to make money and have health insurance for my family.As I grew in age,experience,and stamina,I was less adaptable,i.e.,I was more ethical.This article tells this story through events at various times in my engineering career1.Ethics define how we do the right thing.展开更多
The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± ...The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± 10)°C, leads to obtaining transparent glasses, brown in color and with a non-hygroscopic appearance. The study of glasses dissolution rate, immersed in distilled water at 90°C for 24 days, indicates a considerable chemical durability. The increase in the Fe<sub>2</sub>O<sub>3</sub> content in the vitreous network to the detriment of PbO is a favorable factor for the chemical durability improvement. Different techniques have been used such as X-ray diffraction, infrared spectroscopy, DSC, SEM and density for the study of these glasses. These techniques have led to establish correlations between chemical and structural properties. Thus the results obtained confirmed the creation of P-O-M bonds (M = Pb, Fe) with a strongly covalent nature to the detriment of the hydrated P-O-P bonds and led to the formation, mainly, of pyrophosphate groups. The low melting point of Pb-O makes it possible to play an important role, at the same time, on the viscosity, on the equilibrium between the vitreous bath and the crystallites formed. The dissolution rate obtained is 100 times smaller than that of silicate glasses used as an alternative form for the vitrification of radioactive waste.展开更多
Compacted bentonite-sand(B/S)mixtures have been used as a barrier material in engineered barrier systems(EBSs)of deep geological repositories(DGR)to store nuclear wastes.This study investigates the individual and comb...Compacted bentonite-sand(B/S)mixtures have been used as a barrier material in engineered barrier systems(EBSs)of deep geological repositories(DGR)to store nuclear wastes.This study investigates the individual and combined effects of different chemical compositions of deep groundwaters(chemical factor)at potential repository sites in Canada(the Trenton and Guelph regions in Ontario),heat generated in DGRs(thermal factor),dry densities and mass ratios of bentonite and sand mixtures(physical factors)on the swelling behavior and ability of bentonite-based materials.In this study,swelling tests are conducted on B/S mixtures with different B/S mix ratios(20/80 to 70/30),compacted at different dry densities(ρd=1.6-2 g/cm^(3)),saturated with different types of water(distilled water and simulated deep groundwater of Trenton and Guelph)and exposed to different temperatures(20℃-80℃).Moreover,scanning electron microscopy(SEM)analyses,mercury intrusion porosimetry(MIP)tests and X-ray diffractometry(XRD)analyses are carried out to evaluate the morphological,microstructural and mineralogical characteristics of the B/S mixtures.The test results indicate that the swelling potential of the B/S mixtures is significantly affected by these physical and chemical factors as well as the combined effects of the chemical and thermal factors.A significant decrease in the swelling capacity is observed when the B/S materials are exposed to the aforementioned groundwaters.A large decrease in the swelling capacity is observed for higher bentonite content in the mixtures.Moreover,higher temperatures intensify the chemically-induced reduction of the swelling capacity of the B/S barrier materials.This decrease in the swelling capacity is caused by the chemical and/or microstructural changes of the materials.The results from this research will help engineers to design and build EBSs for DGRs with similar groundwater and thermal conditions.展开更多
Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the i...Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and water.The water was used because it may be employed as a target coolant.The energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and water.For a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness ratio.These two aspects support the use of a pure target,either LBE or water.However,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then decreases.This result supports the addition of water into the LBE target.The angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.展开更多
The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely u...The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.展开更多
The chemical stability of simulated waste forms Zr_(1–x)Nd_xSiO_(4–x/2) was investigated using the static leach test(MCC-1) with lixiviants of three pH values(pH=4, 6.7 and 10) at three temperature points(40, 90 and...The chemical stability of simulated waste forms Zr_(1–x)Nd_xSiO_(4–x/2) was investigated using the static leach test(MCC-1) with lixiviants of three pH values(pH=4, 6.7 and 10) at three temperature points(40, 90 and 150 oC) for periods ranging from 1 to 42 d, and the influence of temperature, pH, as well as their combined effects were explored in detail. The results showed that all the normalized release rate of Nd firstly decreased with leaching time and closed to equilibrium after 14 d. As the temperature increased, the normalized release rate of Nd also increased, but it was no more than 3×10^(–5) g/(m^2·d). And, the normalized release rate of Nd reached the highest values(~5×10^(–5) g/(m^2·d)) when pH=4, whilst the normalized release rate of Nd remained the lowest value(~1×10^(–5) g/(m^2·d)) near neutral environment(pH=6.7).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
Perovskite-based ceramic composites were developed as potential waste form materials for immobilizing cesium(Cs)and iodine(I)with high waste loadings and chemical durability.The perovskite Cs_(3)Bi_(2)I_(9)has high Cs...Perovskite-based ceramic composites were developed as potential waste form materials for immobilizing cesium(Cs)and iodine(I)with high waste loadings and chemical durability.The perovskite Cs_(3)Bi_(2)I_(9)has high Cs(22 wt%)and I(58 wt%)content,and thus can be used as a potential host phase to immobilize these critical radionuclides.In this work,the perovskite Cs_(3)Bi_(2)I_(9)phase was synthesized by a cost effective solution-based approach,and was embedded into a highly durable hydroxyapatite matrix by spark plasma sintering to form dense ceramic composite waste forms.The chemical durabilities of the monolithic Cs_(3)Bi_(2)I_(9)and Cs_(3)Bi_(2)I_(9)-hydroxyapatite composite pellets were investigated by static and semi-dynamic leaching tests,respectively.Cs and I are incongruently released from the matrix for both pure Cs_(3)Bi_(2)I_(9)and composite structures.The normalized Cs release rate is faster than that of I,which can be explained by the difference in the strengths between Cs-I and Bi-I bonds as well as the formation of insoluble micrometer-sized BiOI precipitates.The activation energies of elemental releases based on dissolution and diffusion-controlled mechanisms are determined with significantly higher energy barriers for dissolution from the composite versus that of the monolithic Cs_(3)Bi_(2)I_(9).The ceramic-based composite waste forms exhibit excellent chemical durabilities and waste loadings,commensurate with the state-of-the-art glass-bonded perovskite composites for I and Cs immobilization.展开更多
Radioactive iodine exhibits medical values in radiology,but its excessive emissions can cause environmental pollution.Thus,the capture of radioiodine poses significant engineering for the environment and medical radio...Radioactive iodine exhibits medical values in radiology,but its excessive emissions can cause environmental pollution.Thus,the capture of radioiodine poses significant engineering for the environment and medical radiology.The adsorptive capture of radioactive iodine by metal-organic frameworks(MOFs)has risen to prominence.In this work,a Th-based MOF(denoted as Th-BPYDC)was structurally designed and synthesized,consisting of[Th_(6)(μ_(3)-O)_(4)(μ_(3)-OH)_(4)(H_(2)O)6]^(12+)clusters,abundant bipyridine units,and large cavities that allowed guest molecules diffusion and transmission.Th-BPYDC exhibited the uptake capacities of 2.23 g·g^(-1) and 312.18 mg·g^(-1) towards I_(2) vapor and I_(2) dissolved in cyclohexane,respectively,surpassing its corresponding analogue Th-UiO-67.The bipyridine units boosted the adsorption performance,and Th-BPYDC showed good reusability with high stability.Our work thus opened a new way for the synthesis of MOFs to capture radioactive iodine.展开更多
Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking ...Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking behavior of square rock samples heated from the central borehole.The thermal and mechanical behaviors of two cases,i.e.,the case with large size but low heating rate and the case with small size but high heating rate were compared to study the crack initiation location in the models with different model sizes and heating rates.The simulated stress and temperature fields,as well as the failure pattern,were in good agreement with the experimental observations.The temperature and thermal stress distribution during the heating process in both cases indicated that high tensile stress was concentrated around the thermal gradient front,which resulted in the cracks initiating at the location with a certain distance away from the borehole.The results show that under the same heating rate,crack initiation location moves outwards with the increment of the model size then remains approximately at one location,which reflects the boundary-effect.Furthermore,the results indicate that the relative crack initiation locations in two cases are nearly the same if the ratio between the heating rate in two cases(Tx/Ty)nearly equal to the square of the inverse ratio of corresponding model side lengths((ay/ax)2).This concept is named the scale-heating rate equivalence effect in this study.It is beneficial for studying thermal cracking of rock both numerically and experimentally since the model size can be significantly decreased.展开更多
Rare earth(RE)-containing crystals have been investigated as media for the immobilization of RE fission products from nuclear waste streams.During reprocessing of spent nuclear fuel,fission products including REs,alka...Rare earth(RE)-containing crystals have been investigated as media for the immobilization of RE fission products from nuclear waste streams.During reprocessing of spent nuclear fuel,fission products including REs,alkalis,and alkaline earths released from the fuel.One viable option to immobilize the RE fission products is to incorporate them into chemically durable crystalline phases in specific waste forms.This study summarizes the crystal structures and synthesis methods of six RE-containing compounds that have applications in remediation of RE fission products.These compounds include oxyapatite(AE_(2)RE_(8)(SiO_(4))_(6)O_(2)),oxychloride(REOCl),borosilicate(RE_(3)BSi_(2)O_(10)),pyrochlore(RE_(2)M_(2)O_(7)),monazite(REPO_(4)),and perovskite(REMO_(3))where AE denotes alkaline earth metals and M denotes transition metals.This review provides an overview of literature on the usage of these six compounds for immobilizing RE fission products and summarizes different synthesis methods for producing these compounds.Comparisons of structural parameters with different REs in each compound are also discussed.展开更多
Geological repository of high-level nuclear waste(HLNW),the most feasible approach for the safe and permanent treatment of HLNW without human intervention,has been investigated for years by many researchers.In some co...Geological repository of high-level nuclear waste(HLNW),the most feasible approach for the safe and permanent treatment of HLNW without human intervention,has been investigated for years by many researchers.In some countries,real facilities for the geo-logical repository are already under construction.In Japan,however,due to complicated geologic conditions,especially underground water and fractured rock masses,and the high risk of natural disasters,ensuring the long-term stability of the method remains a struggle.The influential factors include underground water,heat generation from radioactive waste,and thermal and chemical weathering of the surrounding rock mass as a natural barrier.It is difficult to estimate and verify the long-term stability for up to one hundred thousand years,a complicated thermal-hydraulic-mechanical-chemical coupling behavior,via any field test.The objective of the study is to develop a numerical method for predicting the long-term stability of geological repositories.As the first step toward realizing this objec-tive,heating and loading tests on cave model made of man-made rock specimens that are composed of diatoms,gypsum,and water,which are viscoplastic materials,were conducted,based on which a newly proposed numerical method with finite element method(FEM)was used to describe the thermal,mechanical,and time-dependent behavior of the model tests for a geological repository.To ensure the accuracy of the numerical calculations,all the material parameters in the thermoelasto-viscoplastic model with consideration of overconsolidation,the structure,and the influence of intermediate stress were determined via triaxial compression/creep tests under various temperatures,confining stresses,and loading rates.Finally,the validity of the numerical method was demonstrated by model tests over a limited time span.展开更多
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.
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
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.
文摘There are costs for doing the right thing,but regret is not one of those costs.I learned this lesson the hard way throughout a 42-year engineering career.As a young engineer,raising a family,I was more adaptable to management mandates,i.e.,I was more willing to be unethical to keep my job to make money and have health insurance for my family.As I grew in age,experience,and stamina,I was less adaptable,i.e.,I was more ethical.This article tells this story through events at various times in my engineering career1.Ethics define how we do the right thing.
文摘The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± 10)°C, leads to obtaining transparent glasses, brown in color and with a non-hygroscopic appearance. The study of glasses dissolution rate, immersed in distilled water at 90°C for 24 days, indicates a considerable chemical durability. The increase in the Fe<sub>2</sub>O<sub>3</sub> content in the vitreous network to the detriment of PbO is a favorable factor for the chemical durability improvement. Different techniques have been used such as X-ray diffraction, infrared spectroscopy, DSC, SEM and density for the study of these glasses. These techniques have led to establish correlations between chemical and structural properties. Thus the results obtained confirmed the creation of P-O-M bonds (M = Pb, Fe) with a strongly covalent nature to the detriment of the hydrated P-O-P bonds and led to the formation, mainly, of pyrophosphate groups. The low melting point of Pb-O makes it possible to play an important role, at the same time, on the viscosity, on the equilibrium between the vitreous bath and the crystallites formed. The dissolution rate obtained is 100 times smaller than that of silicate glasses used as an alternative form for the vitrification of radioactive waste.
基金the funding support from Natural Sciences and Engineering Research Council of Canada (NSERC)
文摘Compacted bentonite-sand(B/S)mixtures have been used as a barrier material in engineered barrier systems(EBSs)of deep geological repositories(DGR)to store nuclear wastes.This study investigates the individual and combined effects of different chemical compositions of deep groundwaters(chemical factor)at potential repository sites in Canada(the Trenton and Guelph regions in Ontario),heat generated in DGRs(thermal factor),dry densities and mass ratios of bentonite and sand mixtures(physical factors)on the swelling behavior and ability of bentonite-based materials.In this study,swelling tests are conducted on B/S mixtures with different B/S mix ratios(20/80 to 70/30),compacted at different dry densities(ρd=1.6-2 g/cm^(3)),saturated with different types of water(distilled water and simulated deep groundwater of Trenton and Guelph)and exposed to different temperatures(20℃-80℃).Moreover,scanning electron microscopy(SEM)analyses,mercury intrusion porosimetry(MIP)tests and X-ray diffractometry(XRD)analyses are carried out to evaluate the morphological,microstructural and mineralogical characteristics of the B/S mixtures.The test results indicate that the swelling potential of the B/S mixtures is significantly affected by these physical and chemical factors as well as the combined effects of the chemical and thermal factors.A significant decrease in the swelling capacity is observed when the B/S materials are exposed to the aforementioned groundwaters.A large decrease in the swelling capacity is observed for higher bentonite content in the mixtures.Moreover,higher temperatures intensify the chemically-induced reduction of the swelling capacity of the B/S barrier materials.This decrease in the swelling capacity is caused by the chemical and/or microstructural changes of the materials.The results from this research will help engineers to design and build EBSs for DGRs with similar groundwater and thermal conditions.
基金supported by the National Natural Science Foundation of China(No.11875328).
文摘Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and water.The water was used because it may be employed as a target coolant.The energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and water.For a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness ratio.These two aspects support the use of a pure target,either LBE or water.However,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then decreases.This result supports the addition of water into the LBE target.The angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2023A1515011244).
文摘The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.
基金Project supported by the National Natural Science Foundation of China(41302028,41302029,21507105)Thousand Youth Talents Plan(Y42H831301)+3 种基金Key Project of Sichuan Education Department(14ZA0099,15ZB0116)Foundation of Laboratory of National Defense Key Discipline for Nuclear Waste and Environmental Safety,Southwest University of Science and Technology(15yyhk10)the Doctor Foundation in Southwest University of Science and Technology(10zx7126)Hebei Science and Technology Support Program(15211121)
文摘The chemical stability of simulated waste forms Zr_(1–x)Nd_xSiO_(4–x/2) was investigated using the static leach test(MCC-1) with lixiviants of three pH values(pH=4, 6.7 and 10) at three temperature points(40, 90 and 150 oC) for periods ranging from 1 to 42 d, and the influence of temperature, pH, as well as their combined effects were explored in detail. The results showed that all the normalized release rate of Nd firstly decreased with leaching time and closed to equilibrium after 14 d. As the temperature increased, the normalized release rate of Nd also increased, but it was no more than 3×10^(–5) g/(m^2·d). And, the normalized release rate of Nd reached the highest values(~5×10^(–5) g/(m^2·d)) when pH=4, whilst the normalized release rate of Nd remained the lowest value(~1×10^(–5) g/(m^2·d)) near neutral environment(pH=6.7).
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.
基金supported as part of the Center for Performance and Design of Nuclear Waste Forms and Containers(WastePD),an Energy Frontier Research Center(EFRC)funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciences under Award DE-SC0016584。
文摘Perovskite-based ceramic composites were developed as potential waste form materials for immobilizing cesium(Cs)and iodine(I)with high waste loadings and chemical durability.The perovskite Cs_(3)Bi_(2)I_(9)has high Cs(22 wt%)and I(58 wt%)content,and thus can be used as a potential host phase to immobilize these critical radionuclides.In this work,the perovskite Cs_(3)Bi_(2)I_(9)phase was synthesized by a cost effective solution-based approach,and was embedded into a highly durable hydroxyapatite matrix by spark plasma sintering to form dense ceramic composite waste forms.The chemical durabilities of the monolithic Cs_(3)Bi_(2)I_(9)and Cs_(3)Bi_(2)I_(9)-hydroxyapatite composite pellets were investigated by static and semi-dynamic leaching tests,respectively.Cs and I are incongruently released from the matrix for both pure Cs_(3)Bi_(2)I_(9)and composite structures.The normalized Cs release rate is faster than that of I,which can be explained by the difference in the strengths between Cs-I and Bi-I bonds as well as the formation of insoluble micrometer-sized BiOI precipitates.The activation energies of elemental releases based on dissolution and diffusion-controlled mechanisms are determined with significantly higher energy barriers for dissolution from the composite versus that of the monolithic Cs_(3)Bi_(2)I_(9).The ceramic-based composite waste forms exhibit excellent chemical durabilities and waste loadings,commensurate with the state-of-the-art glass-bonded perovskite composites for I and Cs immobilization.
基金support from the Science Challenge Project (Grant No.TZ2016004)the Hunan Provincial Natural Science Foundation of China (Grant No.2021JJ30565).
文摘Radioactive iodine exhibits medical values in radiology,but its excessive emissions can cause environmental pollution.Thus,the capture of radioiodine poses significant engineering for the environment and medical radiology.The adsorptive capture of radioactive iodine by metal-organic frameworks(MOFs)has risen to prominence.In this work,a Th-based MOF(denoted as Th-BPYDC)was structurally designed and synthesized,consisting of[Th_(6)(μ_(3)-O)_(4)(μ_(3)-OH)_(4)(H_(2)O)6]^(12+)clusters,abundant bipyridine units,and large cavities that allowed guest molecules diffusion and transmission.Th-BPYDC exhibited the uptake capacities of 2.23 g·g^(-1) and 312.18 mg·g^(-1) towards I_(2) vapor and I_(2) dissolved in cyclohexane,respectively,surpassing its corresponding analogue Th-UiO-67.The bipyridine units boosted the adsorption performance,and Th-BPYDC showed good reusability with high stability.Our work thus opened a new way for the synthesis of MOFs to capture radioactive iodine.
基金supported by the National Natural Science Foundation of China(Grant No.51874065)the National Major Scientific Instruments Development Project(Grant No.51627804).
文摘Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking behavior of square rock samples heated from the central borehole.The thermal and mechanical behaviors of two cases,i.e.,the case with large size but low heating rate and the case with small size but high heating rate were compared to study the crack initiation location in the models with different model sizes and heating rates.The simulated stress and temperature fields,as well as the failure pattern,were in good agreement with the experimental observations.The temperature and thermal stress distribution during the heating process in both cases indicated that high tensile stress was concentrated around the thermal gradient front,which resulted in the cracks initiating at the location with a certain distance away from the borehole.The results show that under the same heating rate,crack initiation location moves outwards with the increment of the model size then remains approximately at one location,which reflects the boundary-effect.Furthermore,the results indicate that the relative crack initiation locations in two cases are nearly the same if the ratio between the heating rate in two cases(Tx/Ty)nearly equal to the square of the inverse ratio of corresponding model side lengths((ay/ax)2).This concept is named the scale-heating rate equivalence effect in this study.It is beneficial for studying thermal cracking of rock both numerically and experimentally since the model size can be significantly decreased.
文摘Rare earth(RE)-containing crystals have been investigated as media for the immobilization of RE fission products from nuclear waste streams.During reprocessing of spent nuclear fuel,fission products including REs,alkalis,and alkaline earths released from the fuel.One viable option to immobilize the RE fission products is to incorporate them into chemically durable crystalline phases in specific waste forms.This study summarizes the crystal structures and synthesis methods of six RE-containing compounds that have applications in remediation of RE fission products.These compounds include oxyapatite(AE_(2)RE_(8)(SiO_(4))_(6)O_(2)),oxychloride(REOCl),borosilicate(RE_(3)BSi_(2)O_(10)),pyrochlore(RE_(2)M_(2)O_(7)),monazite(REPO_(4)),and perovskite(REMO_(3))where AE denotes alkaline earth metals and M denotes transition metals.This review provides an overview of literature on the usage of these six compounds for immobilizing RE fission products and summarizes different synthesis methods for producing these compounds.Comparisons of structural parameters with different REs in each compound are also discussed.
基金substantially supported by financial support from Grant-in-Aid Scientific Research(B)(Grant No.17H03304)JSPS,and JSPS KAKENHI(Grant No.JP20K14823).
文摘Geological repository of high-level nuclear waste(HLNW),the most feasible approach for the safe and permanent treatment of HLNW without human intervention,has been investigated for years by many researchers.In some countries,real facilities for the geo-logical repository are already under construction.In Japan,however,due to complicated geologic conditions,especially underground water and fractured rock masses,and the high risk of natural disasters,ensuring the long-term stability of the method remains a struggle.The influential factors include underground water,heat generation from radioactive waste,and thermal and chemical weathering of the surrounding rock mass as a natural barrier.It is difficult to estimate and verify the long-term stability for up to one hundred thousand years,a complicated thermal-hydraulic-mechanical-chemical coupling behavior,via any field test.The objective of the study is to develop a numerical method for predicting the long-term stability of geological repositories.As the first step toward realizing this objec-tive,heating and loading tests on cave model made of man-made rock specimens that are composed of diatoms,gypsum,and water,which are viscoplastic materials,were conducted,based on which a newly proposed numerical method with finite element method(FEM)was used to describe the thermal,mechanical,and time-dependent behavior of the model tests for a geological repository.To ensure the accuracy of the numerical calculations,all the material parameters in the thermoelasto-viscoplastic model with consideration of overconsolidation,the structure,and the influence of intermediate stress were determined via triaxial compression/creep tests under various temperatures,confining stresses,and loading rates.Finally,the validity of the numerical method was demonstrated by model tests over a limited time span.
