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Sample records for montmorillonite engineered barriers

  1. Electrolyte diffusion in compacted montmorillonite engineered barriers

    International Nuclear Information System (INIS)

    Jahnke, F.M.; Radke, C.J.

    1985-09-01

    The bentonite-based engineered barrier or packing is a proposed component of several designs conceived to dispose of high-level nuclear waste in geologic repositories. Once radionuclides escape the waste package, they must first diffuse through the highly impermeable clay-rich barrier before they reach the host repository. To determine the effectiveness of the packing as a sorption barrier in the transient release period and as a mass-transfer barrier in the steady release period over the geologic time scales involved in nuclear waste disposal, a fundamental understanding of the diffusion of electrolytes in compacted clays is required. We present, and compare with laboratory data, a model quantifying the diffusion rates of cationic cesium and uncharged tritium in compacted montmorillonite clay. Neutral tritium characterizes the geometry (i.e., tortuosity) of the particulate gel. After accounting for cation exchange, we find that surface diffusion is the dominant mechanism of cation transport, with an approximate surface diffusion coefficient of 2 x 10 -6 cm 2 /s for cesium. This value increases slightly with increasing background ionic strength. The implications of this work for the packing as a migration barrier are twofold. During the transient release period, K/sub d/ values are of little importance in retarding ion migration. This is because sorption also gives rise to a surface diffusion path, and it is surface diffusion which controls the diffusion rate of highly sorbing cations in compacted montmorillonite. During the steady release period, the presence of surface diffusion leads to a flux through the packing which is greatly enhanced. In either case, if surface diffusion is neglected, the appropriate diffusion coefficient of ions in compacted packing will be in considerable error relative to current design recommendations. 11 refs., 4 figs., 1 tab

  2. Clay-based materials for engineered barriers: a review

    International Nuclear Information System (INIS)

    Lajudie, A.; Raynal, J.; Petit, J.C.; Toulhoat, P.

    1994-01-01

    The potential importance of backfilling and plugging in underground radioactive waste repositories has led different research institutions to carry out extensive studies of swelling clay materials for the development of engineered barriers in underground conditions. These materials should combine a variety of hydro-thermo-mechanical and geochemical properties: impermeability, swelling ability in order to fill all void space, heat transfer and retention capacity for the most noxious radionuclides. Smectite clays best exhibit these properties and most of the research effort has been devoted to this type of materials. In this paper, mineralogical composition, sodium or calcium content, thermo-hydro-mechanical properties, swelling pressure, hydraulic and thermal conductivity, and chemical properties of five smectite clays selected by five major nuclear countries are reviewed: Avonseal montmorillonite (Canada), MX 80 montmorillonite (Sweden), Montigel montmorillonite (Switzerland), S-2 montmorillonite (Spain), and Fo-Ca inter stratified kaolinite/beidellite (France). (J.S.). 29 refs., 5 figs., 3 tabs

  3. Engineered barriers: current status

    International Nuclear Information System (INIS)

    Atkinson, A.; Marsh, G.P.

    1988-01-01

    This report summarises the current state of research relevant to assessing the performance of engineered barriers made of steel and concrete in radioactive waste repositories. The objective of these barriers is to contain the radionuclides within them by providing both physical and chemical impediment to their release. The physical barriers are of most value for highly soluble isotopes with relatively short half-lives (eg 137 Cs), since they can provide containment until a large fraction of the activity has decayed. In addition they can facilitate retrievability for some period after disposal. The chemical barriers operate by beneficial conditioning of the near field groundwater and providing sites for sorption of radionuclides. Both of these reduce the aqueous concentration of radionuclides in the near field. (author)

  4. Transparent films based on PLA and montmorillonite with tunable oxygen barrier properties

    DEFF Research Database (Denmark)

    Svagan, Anna; Åkesson, Anna; Cárdenas, Marité

    2012-01-01

    Polylactide (PLA) is viewed as a potential material to replace synthetic plastics (e.g., poly(ethylene terephthalate) (PET)) in food packaging, and there have been a number of developments in this direction. However, for PLA to be competitive in more demanding uses such as the packaging of oxygen......-sensitive foods, the oxygen permeability coefficient (OP) needs to be reduced by a factor of ∼10. To achieve this, a layer-by-layer (Lbl) approach was used to assemble alternating layers of montmorillonite clay and chitosan on extruded PLA film surfaces. When 70 bilayers were applied, the OP was reduced by 99...... and 96%, respectively, at 20 and 50% RH. These are, to our knowledge, the best improvements in oxygen barrier properties ever reported for a PLA/clay-based film. The process of assembling such multilayer structures was characterized using a quartz crystal microbalance with dissipation monitoring...

  5. Performance of engineered barriers

    International Nuclear Information System (INIS)

    Rajaram, V.; Dean, P.V.; McLellan, S.A.

    1997-01-01

    Engineered barriers, both vertical and horizontal, have been used to isolate hazardous wastes from contact, precipitation, surface water and groundwater. The primary objective of this study was to determine the performance of subsurface barriers installed throughout the U.S. over the past 20 years to contain hazardous wastes. Evaluation of Resource Conservation and Recovery Act (RCRA) Subtitle C or equivalent caps was a secondary objective. A nationwide search was launched to select hazardous waste sites at which vertical barrier walls and/or caps had been used as the containment method. None of the sites selected had an engineered floor. From an initial list of 130 sites, 34 sites were selected on the basis of availability of monitoring data for detailed analysis of actual field performance. This paper will briefly discuss preliminary findings regarding the design, construction quality assurance/construction quality control (CQA/CQC), and monitoring at the 34 sites. In addition, the short-term performance of these sites (less than 5 years) is presented since very little long-term performance data was available

  6. Hemicelluloses/montmorillonite hybrid films with improved mechanical and barrier properties

    Science.gov (United States)

    Chen, Ge-Gu; Qi, Xian-Ming; Li, Ming-Peng; Guan, Ying; Bian, Jing; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2015-11-01

    A facile and environmentally friendly method was introduced to incorporate montmorillonite (MMT) as an inorganic phase into quaternized hemicelluloses (QH) for forming hemicellulose-based films. Two fillers, polyvinyl alcohol (PVA) and chitin nanowhiskers (NCH), were added into the hemicelluloses/MMT hybrid matrices to prepare hybrid films, respectively. The hybrid films were nanocomposites with nacre-like structure and multifunctional characteristics including higher strength and good oxygen barrier properties via the electrostatic and hydrogen bonding interactions. The addition of PVA and NCH could induce changes in surface topography, and effectively enhance mechanical strength, thermal stability, transparency, and oxygen barrier properties. The tensile strengths of the composite films FPVA(0.3), FPVA(0.5), and FNCH(0.8) were 53.7, 46.3, and 50.1 MPa, respectively, which were 171%, 134%, and 153% larger than the FQH-MMT film (19.8 MPa). The tensile strength, and oxygen transmission rate of QH-MMT-PVA film were better than those of quaternized hemicelluloses/MMT films. Thus, the proper filler is very important for the strength of the hybrid film. These results provide insights into the understanding of the structural relationships of hemicellulose-based composite films in coating and packaging application for the future.

  7. Barrier Properties of Polylactic Acid in Cellulose Based Packages Using Montmorillonite as Filler

    Directory of Open Access Journals (Sweden)

    Daniela Sánchez Aldana

    2014-09-01

    Full Text Available Polylactic acid (PLA and montmorillonite (CB as filler were studied as coatings for cellulose based packages. Amorphous (AM and semi crystalline (SC PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was three concentrations and coating was performed by casting. Contact angle (CA, water vapor (WVP and grease permeabilities were measured for each resultant package and were compared to commercial materials (Glassine Paper, Grease Proof Papers 1 and 2 produced commercially. Significant differences were found and the main factors were the type and concentration of PLA. The best values were: for grease penetration, +1800 s; WVP from 161.36 to 237.8 g·µm·kPa−1·m−2·d−1 and CA from 69° to 73° for PLA–AM 0.5% and CB variable. These parameters are comparable to commercial packages used in the food industry. DSC revealed three different thermal events for PLA–SC and just Tg for PLA–AM. Crystallinity was also verified, obtaining a ΔHcrys of 3.7 J·g−1 for PLA–SC and 14 J·g−1 for PLA–SC–BC, evidencing clay interaction as a crystal nucleating agent. Differences found were explained on terms of the properties measured, where structural and chemical arrays of the coatings play a fundamental role for the barrier properties.

  8. Development of engineered barrier

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

    1999-03-01

    Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

  9. Development of engineered barrier

    International Nuclear Information System (INIS)

    Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

    1999-03-01

    Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and 316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

  10. Polylactide/Montmorillonite Hybrid Latex as a Barrier Coating for Paper Applications

    Directory of Open Access Journals (Sweden)

    Davide Bandera

    2016-03-01

    Full Text Available We developed a paper coating for the potential application in food packaging based on polylactide and montmorillonite. It is applied to the paper in the form of a stable, water-based latex with a solid content of 25–28 wt %. The latex is prepared from a commercially available polylactide, surfactants, montmorillonite, a plasticizer, chloroform (to be removed later and water by an emulsion/solvent evaporation procedure. This coating formulation is applied to the paper substrate by bar-coating, followed by hot-pressing at 150 °C. The coated papers achieved up to an 85% improvement in water vapor transmission rates when compared to the pristine papers. The coating latex is prepared from inexpensive materials and can be used for a solvent-free coating process. In addition, the ingredients of the latex are non-toxic; thus, the coated papers can be safely used for food packaging.

  11. Gas barrier properties of nanocomposites based on in situ polymerized poly(n-butyl methacrylate) in the presence of surface modified montmorillonite

    Czech Academy of Sciences Publication Activity Database

    Herrera-Alonso, J. M.; Sedláková, Zdeňka; Marand, E.

    2010-01-01

    Roč. 349, 1-2 (2010), s. 251-257 ISSN 0376-7388 R&D Projects: GA AV ČR KAN100500651; GA MŠk ME09058 Institutional research plan: CEZ:AV0Z40500505 Keywords : barrier membranes * nanocomposites * montmorillonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.673, year: 2010

  12. Engineered barriers: current status 1989

    International Nuclear Information System (INIS)

    Atkinson, A.; Marsh, G.B.

    1989-06-01

    This report summarises the current state of research relevant to assessing the performance of engineered barriers made of steel and concrete in radioactive waste repositories. The objective of these barriers is to contain substantially the radionuclides within them by providing both physical and chemical impediment to their release. The physical barriers are of most value for highly soluble isotopes with relatively short half-lives (eg 137 Cs), since they can provide a measure of containment until a large fraction of the activity has decayed. In addition they can facilitate retrievability for some period after disposal. The chemical barriers operate by beneficial conditioning of the near field groundwater and providing sites for sorption of radionuclides. Both of these reduce the aqueous concentration of radionuclides in the near field. (author)

  13. Remediation of arsenic-contaminated groundwater using media-injected permeable reactive barriers with a modified montmorillonite: sand tank studies.

    Science.gov (United States)

    Luo, Ximing; Liu, Haifei; Huang, Guoxin; Li, Ye; Zhao, Yan; Li, Xu

    2016-01-01

    A modified montmorillonite (MMT) was prepared using an acid activation-sodium activation-iron oxide coating method to improve the adsorption capacities of natural MMTs. For MMT, its interlamellar distance increased from 12.29 to 13.36 Å, and goethite (α-FeOOH) was intercalated into its clay layers. Two novel media-injected permeable reactive barrier (MI-PRB) configurations were proposed for removing arsenic from groundwater. Sand tank experiments were conducted to investigate the performance of the two MI-PRBs: Tank A was filled with quartz sand. Tank B was packed with quartz sand and zero-valent iron (ZVI) in series, and the MMT slurry was respectively injected into them to form reactive zones. The results showed that for tank A, total arsenic (TA) removal of 98.57% was attained within the first 60 mm and subsequently descended slowly to 88.84% at the outlet. For tank B, a similar spatial variation trend was observed in the quartz sand layer, and subsequently, TA removal increased to ≥99.80% in the ZVI layer. TA removal by MMT mainly depended on both surface adsorption and electrostatic adhesion. TA removal by ZVI mainly relied on coagulation/precipitation and adsorption during the iron corrosion. The two MI-PRBs are feasible alternatives for in situ remediation of groundwater with elevated As levels.

  14. Engineered Barrier Test Facility status report, 1984

    International Nuclear Information System (INIS)

    Phillips, S.J.; Adams, M.R.; Gilbert, T.W.; Meinhardt, C.C.; Mitchell, R.M.; Waugh, W.J.

    1985-02-01

    This report provides a general summary of activities completed to date at the Hanford Engineered Barrier Test Facility. This facility is used to test and compare construction practices and performance of alternative designs of engineered barrier cover systems. These cover systems are being evaluated for potential use for isolation and confinement of buried waste disposal structures

  15. Barrier Properties and Structural Study of Nanocomposite of HDPE/Montmorillonite Modified with Polyvinylalcohol

    Directory of Open Access Journals (Sweden)

    María C. Carrera

    2013-01-01

    Full Text Available In this work was studied the permeation of CO2 in films of high-density polyethylene (HDPE and organoclay modified with polyvinylalcohol (MMTHDTMA/PVA obtained from melt blending. Permeation study showed that the incorporation of the modified organoclay generates a significant effect on the barrier properties of HDPE. When a load of 2 wt% of MMTHDTMA/PVA was incorporated in the polymer matrix, the flow of CO2 decreased 43.7% compared to pure polyethylene. The results of TEM showed that clay layers were dispersed in the polymeric matrix, obtaining an exfoliated-structure nanocomposite. The thermal stability of nanocomposite was significantly enhanced with respect to the pristine HDPE. DSC results showed that the crystallinity was maintained as the pure polymeric matrix. Consequently, the decrease of permeability was attributable only to the effect of tortuosity generated by the dispersion of MMTHDTMA/PVA. Notably the mechanical properties remain equal to those of pure polyethylene, but with an increase in barrier properties to CO2. This procedure allows obtaining nanocomposites of HDPE with a good barrier property to CO2 which would make it competitive in the use of packaging.

  16. Design of engineered sorbent barriers

    International Nuclear Information System (INIS)

    Jones, E.O.; Freeman, H.D.

    1988-08-01

    A sorbent barrier uses sorbent material such as activated carbon or natural zeolites to prevent the migration of radionuclides from a low-level waste site to the aquifer. The sorbent barrier retards the movement of radioactive contaminants, thereby providing time for the radionuclides to decay. Sorbent barriers can be a simple, effective, and inexpensive method for reducing the migration of radionuclides to the environment. Designing a sorbent barrier consists of using soil and sorbent material properties and site conditions as input to a model which will determine the necessary sorbent barrier thickness to meet contaminant limits. The paper will cover the following areas: techniques for measuring sorption properties of barrier materials and underlying soils, use of a radionuclide transport model to determine the required barrier thickness and performance under a variety of site conditions, and cost estimates for applying the barrier. 8 refs., 6 figs., 1 tab

  17. Design of engineered sorbent barriers

    International Nuclear Information System (INIS)

    Jones, E.O.; Freeman, H.D.

    1988-01-01

    A sorbent barrier uses sorbent material such as activated carbon or natural zeolites to prevent the migration of radionuclides from a low-level waste site to the aquifer. The sorbent barrier retards the movement of radioactive contaminants, thereby providing time for the radionuclides to decay. Sorbent barriers can be a simple, effective, and inexpensive method for reducing the migration of radionuclides to the environment. Designing a sorbent barrier consists of using soil and sorbent material properties and site conditions as input to a model which will determine the necessary sorbent barrier thickness to meet contaminant limits. The paper covers the following areas: techniques for measuring sorption properties of barrier materials and underlying soils, use of a radionuclide transport model to determine the required barrier thickness and performance under a variety of site conditions, and cost estimates for applying the barrier

  18. Synthesis of polymer hybrid latex poly(methyl methacrylate-co-butyl acrylate) with organo montmorillonite via miniemulsion polymerization method for barrier paper

    Science.gov (United States)

    Chanra, J.; Budianto, E.; Soegijono, B.

    2018-03-01

    Hybrid polymer latex based on combination of organic-inorganic materials, poly(methyl methacrylate-co-butyl acrylate) (PMMBA) and organo-montmorillonite (OMMT) were synthesized via miniemulsion polymerization technique. Modification of montmorillonite (MMT) through the incorporation of myristyltrimethylammonium bromide (MTAB) into the clay’s interlayer spaces were investigated by Small-Angle X-ray Scattering (SAXS), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). Barrier property and thermal stability of polymer latex film sample were investigated through its Water Vapor Transmission Rate (WVTR) and Thermogravimetric Analysis (TGA). The results indicated that addition of OMMT as filler in PMMBA increased the barrier property and thermal stability of the latex film. Addition of 8.0% (wt) OMMT increased the barrier property and thermal stability. Miniemusion polymerization process with higher addition (>8.0 wt%) of OMMT resulting in high latex viscosity, particle size, and high amount of coagulum. The utilization of this hybrid polymer could benefits paper and board industries to produce high quality barrier paper for food packaging.

  19. Barrier Engineered Quantum Dot Infrared Photodetectors

    Science.gov (United States)

    2015-06-01

    251108. 6. Barve, Ajit V., Saumya Sengupta, Jun Oh Kim, John Montoya , Brianna Klein, Mohammad Ali Shirazi, Marziyeh Zamiri et al., "Barrier selection... H . Kim, Z-B. Tian, and Sanjay Krishna. "Barrier Engineered Infrared Photodetectors Based on Type-II InAs/GaSb Strained Layer Superlattices." (2013

  20. Engineering kinetic barriers in copper metallization

    International Nuclear Information System (INIS)

    Huang Hanchen; Wei, H.L.; Woo, C.H.; Zhang, X.X.

    2002-01-01

    In metallization processes of integrated circuits, it is desirable to deposit the metal lines (aluminum or copper) fast and at low temperatures. However, the lines (films) usually consist of undesirable columns and voids, because of the absence of sufficient diffusion--a direct result of large kinetic barriers. Following the proposal and realization of the three-dimensional Ehrlich-Schwoebel (3D ES) barrier, we present here a method to engineer this kinetic barrier so as to improve quality of deposited copper films. We deposit copper films by magnetron sputtering, characterize the film structure and texture by using the scanning electron microscope and the x-ray diffraction, respectively. Taking indium as surfactant during copper deposition, we have achieved much better density and bottom coverage of copper filled trenches. The characterizations show that the improvement is the result of the 3D ES barrier reduction caused by indium addition. Engineering the 3D ES barrier therefore leads to improved film quality

  1. Barriers to student success in engineering education

    Science.gov (United States)

    Boles, Wageeh; Whelan, Karen

    2017-07-01

    In the UK, the USA and Australia, there have been calls for an increase in the number of engineering graduates to meet the needs of current global challenges. Universities around the world have been grappling with how to both attract more engineering students and to then retain them. Attrition from engineering programmes is disturbingly high. This paper reports on an element of research undertaken through an Australian Learning and Teaching Council-funded Fellowship that investigated the factors leading to student attrition in engineering programmes, by identifying barriers to student success. Here, we contrast a review of the literature related to student barriers and success with student perceptions, gathered through a series of focus groups and interviews at three Australian universities. We also present recommendations for action to try to remove barriers to student success.

  2. Thermal barrier coatings application in diesel engines

    Science.gov (United States)

    Fairbanks, J. W.

    1995-01-01

    Commercial use of thermal barrier coatings in diesel engines began in the mid 70's by Dr. Ingard Kvernes at the Central Institute for Industrial Research in Oslo, Norway. Dr. Kvernes attributed attack on diesel engine valves and piston crowns encountered in marine diesel engines in Norwegian ships as hot-corrosion attributed to a reduced quality of residual fuel. His solution was to coat these components to reduce metal temperature below the threshold of aggressive hot-corrosion and also provide protection. Roy Kamo introduced thermal barrier coatings in his 'Adiabatic Diesel Engine' in the late 70's. Kamo's concept was to eliminate the engine block water cooling system and reduce heat losses. Roy reported significant performance improvements in his thermally insulated engine at the SAE Congress in 1982. Kamo's work stimulates major programs with insulated engines, particularly in Europe. Most of the major diesel engine manufacturers conducted some level of test with insulated combustion chamber components. They initially ran into increased fuel consumption. The German engine consortium had Prof. Woschni of the Technical Institute in Munich. Woschni conducted testing with pistons with air gaps to provide the insulation effects. Woschni indicated the hot walls of the insulated engine created a major increase in heat transfer he refers to as 'convection vive.' Woschni's work was a major factor in the abrupt curtailment of insulated diesel engine work in continental Europe. Ricardo in the UK suggested that combustion should be reoptimized for the hot-wall effects of the insulated combustion chamber and showed under a narrow range of conditions fuel economy could be improved. The Department of Energy has supported thermal barrier coating development for diesel engine applications. In the Clean Diesel - 50 Percent Efficient (CD-50) engine for the year 2000, thermal barrier coatings will be used on piston crowns and possibly other components. The primary purpose of the

  3. Engineered Barrier System: Physical and Chemical Environment

    International Nuclear Information System (INIS)

    Dixon, P.

    2004-01-01

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

  4. Systems study on engineered barriers: barrier performance analysis

    International Nuclear Information System (INIS)

    Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

    1980-09-01

    A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed

  5. Systems study on engineered barriers: barrier performance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

    1980-09-01

    A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed.

  6. Evaluation of synthetic zeolite as engineering passive permeable reactive barrier

    International Nuclear Information System (INIS)

    Ibrahim, O.A.A.

    2011-01-01

    The presence of toxic pollutants in groundwater brings about significant changes in the properties of water resources and has to be avoided in order to preserve the environmental quality. Heavy metals are among the most dangerous inorganic water pollutants, that related to many anthropogenic sources and their compounds are extremely toxic. The treatment of contaminated groundwater is among the most difficult and expensive environmental problems. Over the past years, permeable reactive barriers have provided an increasingly important role in the passive insitu treatment of contaminated groundwater. There are a large number of materials that are able to immobilize contaminants by sorption, including granulated active carbon, zeolite, montmorillonite, peat, compost, sawdust, etc. Zeolite X is a synthetic counterpart of the naturally occurring mineral Faujasite. It has one of the largest cavities and cavity entrances of any known zeolites. The main aim of this work is to examine the possibility of using synthetic zeolite X as an engineering permeable reactive barrier to remove heavy metals from a contaminated groundwater. Within this context, the following investigations were carried out: 1. Review on the materials most commonly used as engineered permeable reactive barriers to identify the important features to be considered in the examination of the proposed permeable reactive barrier material (zeolite X). 2. Synthesis of zeolite X and characterization of the synthesized material using different techniques. 3. Batch tests were carried out to characterize the equilibrium and kinetic sorption properties of the synthesized zeolite X towards the concerned heavy metals; zinc and cadmium ions. 4. Column tests were also performed to determine the design factors for permeable reactive barrier against zinc and cadmium ions solutions.Breakthrough curves measured in such experiments used to determine the hydrodynamic dispersion coefficients for both metal ions. 5. Analytical

  7. Near-Surface Engineered Environmental Barrier Integrity

    International Nuclear Information System (INIS)

    Piet, S.J.; Breckenridge, R.P.

    2002-01-01

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R and D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combine s selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo-transpiration, capillary, and grout-based barriers will be examined

  8. Prototype Engineered Barrier System Field Tests

    International Nuclear Information System (INIS)

    Ramirez, A.L.; Beatty, J.; Buscheck, T.A.

    1989-01-01

    This paper presents selected preliminary results obtained during the first 54 days of the Prototype Engineered Barrier System Field Tests (PEBSFT) that are being performed in G-Tunnel within the Nevada Test Site. The test described is a precursor to the Engineered Barrier Systems Field Tests (EBSFT). The EBSFT will consist of in situ tests of the geohydrologic and geochemical environment in the near field (within a few meters) of heaters emplaced in welded tuff to simulate the thermal effects of waste packages. The PEBSFTs are being conducted to evaluate the applicability of measurement techniques, numerical models, and procedures for future investigations that will be conducted in the Exploratory Shaft Facilities of the Yucca Mountain Project (YMP). The paper discusses the evolution of hydrothermal behavior during the prototype test, including rock temperatures, changes in rock moisture content, air permeability of fractures, gas pressures, and rock mass gas-phase humidity. 10 refs., 12 figs

  9. Engineered Barrier System: Physical and Chemical Environment

    Energy Technology Data Exchange (ETDEWEB)

    P. Dixon

    2004-04-26

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

  10. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    R. Jarek

    2004-11-23

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.

  11. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    International Nuclear Information System (INIS)

    Jarek, R.

    2004-01-01

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports

  12. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    International Nuclear Information System (INIS)

    G.H. Nieder-Westermann

    2005-01-01

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports

  13. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    G.H. Nieder-Westermann

    2005-04-07

    The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.

  14. Synergistic reinforcing effect of TiO2 and montmorillonite on potato starch nanocomposite films: Thermal, mechanical and barrier properties.

    Science.gov (United States)

    Oleyaei, Seyed Amir; Almasi, Hadi; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

    2016-11-05

    In this study, ternary potato starch (PS) bionanocomposite films containing two types of nanoparticles, sodium montmorillonite (MMT), one-dimensional (1D) clay platelets, (3 and 5wt%) and TiO2, three-dimensional (3D) nanospheres, (0.5, 1 and 2wt%), are prepared using solvent casting method. X-ray diffraction (XRD) test confirms the completely exfoliated structure formed in the PS-MMT nanocomposites containing 3 and 5% MMT. The success of the formation of new hydrogen bonds between the hydroxyl groups of starch and nanofillers is confirmed by Fourier transform infrared (FTIR) spectroscopy. Tensile strength (TS), elongation at break (EB), glass transition temperature (Tg), and melting point (Tm) of the films are also enhanced after MMT and TiO2 incorporation. The water vapor permeability (WVP) and the visible, UVA, UVB and UVC lights transmittance decreases upon TiO2 and MMT content increasing. Generally, a synergistic effect is observed between MMT and TiO2 at lower concentrations of MMT. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Reliability modeling of an engineered barrier system

    International Nuclear Information System (INIS)

    Ananda, M.M.A.; Singh, A.K.; Flueck, J.A.

    1993-01-01

    The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered barrier system (EBS), which is known to be one of the key components in a deep geological repository for high level radioactive waste (HLW). The EBS failure time can more realistically be modelled by an IFR distribution, since the failure rate for the EBS is not expected to decrease with time. In this paper, we use an IFR distribution to develop a reliability model for the EBS

  16. Reliability modeling of an engineered barrier system

    International Nuclear Information System (INIS)

    Ananda, M.M.A.; Singh, A.K.; Flueck, J.A.

    1993-01-01

    The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered barrier system (EBS), which is known to be one of the key components in a deep geological repository for high level radioactive waste (HLW). The EBS failure time can more realistically be modelled by an IFR distribution, since the failure rate for the EBS is not expected to decrease with time. In this paper, an IFR distribution is used to develop a reliability model for the EBS

  17. Nanocomposite biofilms obtained from Whitemouth croaker (Micropogonias furnieri) protein isolate and Montmorillonite: evaluation of the physical, mechanical and barrier properties

    International Nuclear Information System (INIS)

    Cortez-Vega, William Renzo; Bagatini, Daniela Cardozo; Souza, Juliana Tais Andreghetto de; Prentice, Carlos

    2013-01-01

    The objective of this study was to evaluate the properties of nanocomposite biofilms based on Whitemouth croaker (Micropogonias furnieri) protein isolate with organophilic clays. Initially the croaker protein isolate (CPI) was obtained using the pH shifting process from by-products of croaker industrialization. A Box and Behnken experimental design was used to develop the films, with three levels of CPI (2, 3.5 and 5 g.100 g -1 solution), montmorillonite MMT clay (0.3, 0.5 and 0.7 g.100 g -1 solution) and glycerol (25, 30 and 35 g.100g -1 CPI). The polymeric films were produced by the 'casting technique'. The tensile strength values ranged from 7.2 to 10.7 MPa and the elongation values from 39.6 to 45.8 %. The water vapor permeability (WVP) values ranged from 3.2 to 5.5 (g.mm.m -2 .d -1 ) and the CPI had an average protein content of 97.87 % protein (d. b.). It was concluded that the nanocomposite films produced from CPI with MMT were promising from the standpoint of their mechanical properties, visual appearance and easy handling, as well as for their low water vapor permeability and low water solubility. With respect to their mechanical properties, the concentrations of CPI and MMT were the main factors influencing the development of the nanocomposite films. The results obtained from the experimental design indicated that 3.5 g of CPI.100 g -1 solution, 0.5 g of MMT.100 g -1 solution and 30 g of glycerol.100 g -1 CPI would be the ideal parameters for the development of nanocomposite films by 'casting'. (author)

  18. Thermal barrier coatings - Technology for diesel engines

    International Nuclear Information System (INIS)

    Harris, D.H.; Lutz, J.

    1988-01-01

    Thermal Barrier Coatings (TBC) are a development of the aerospace industry primarily aimed at hot gas flow paths in turbine engines. TBC consists of zirconia ceramic coatings applied over (M)CrAlY. These coatings can provide three benefits: (1) a reduction of metal surface operating temperatures, (2) a deterrent to hot gas corrosion, and (3) improved thermal efficiencies. TBC brings these same benefits to reciprocal diesel engines but coating longevity must be demonstrated. Diesels require thicker deposits and have challenging geometries for the arc-plasma spray (APS) deposition process. Different approaches to plasma spraying TBC are required for diesels, especially where peripheral edge effects play a major role. Bondcoats and ceramic top coats are modified to provide extended life as determined by burner rig tests, using ferrous and aluminum substrates

  19. State of R and D of radioactive waste disposal (5). R and D of low level radioactive waste disposal. Engineered barrier: evaluation of barrier materials

    International Nuclear Information System (INIS)

    Hironaga, Michihiko

    2008-01-01

    The Central Research Institute of Electric Power Industry (CRIEPI) has researched and developed the long-term durability evaluation of engineered barrier materials for the facility of sub-surface disposal at intermediate depth. The important functions of engineered barrier are mechanical stability of construction, low hydraulic conductivity and diffusivity, and absorption of nuclide. A natural barrier plays an important part in nuclide transfer. Some examples of researches on the engineered barrier with cement and bentonite are reported. They contained the leaching test of hardened cement paste using X-ray microanalysis, relation between the dissociation rate of montmorillonite and pH from 15 to 70 deg C, and the mechanism of gas permeability of dense bentonite. The results of leaching test showed that the modified underground water leached smaller amount of ions than the ion exchanged water. The sediment was found on the surface of hardened paste. The dissociation rate of smectite under alkaline conditions showed almost the same values as neutral conditions at 15 deg C. (S.Y.)

  20. Effect of the addition order and amylose content on mechanical, barrier and structural properties of films made with starch and montmorillonite.

    Science.gov (United States)

    Romero-Bastida, C A; Bello-Pérez, L A; Velazquez, G; Alvarez-Ramirez, J

    2015-01-01

    This study considered the effect of amylose content (30% and 70%), montmorillonite (MMT) fraction (5 and 15%) and preparation method on mechanical and barrier properties of starch/clay nanocomposites prepared by casting. In Method 1, (30% w/w) glycerol was incorporated before starch gelatinization and MMT addition, while in Method 2 after gelatinization and MMT addition. Nanocomposites with higher amount of MMT showed the highest tensile strength and Young's modulus for both preparation methods. Method 1 favored nanocomposite properties of films with less amylose content, meanwhile Method 2 favored nanocomposites properties with higher amylose content. Water vapor permeability did not decrease significantly in starch films with different amylose content with the two different preparation methods. X-ray diffraction of the starch films indicated intercalated structures. Higher melting temperature (Tm) was found for nanocomposites with Method 2, indicating more ordered structures. Films with 70% amylose content have higher Tm than films with 30% amylose. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Engineered barrier development for a nuclear waste repository in basalt

    International Nuclear Information System (INIS)

    Smith, M.J.

    1980-05-01

    The BWIP Engineered Barrier Program has been developed to provide an integrated approach to the development of site-specific Engineered Barrier assemblages for a repository located in basalt. The goal of this program is to specify engineered and natural barriers which will ensure that nuclear and non-radioactive hazardous materials emplaced in a repository in basalt do not exceed acceptable rates of release to the biosphere. A wide range of analytical and experimental activities related to the basalt repository environment, waste package environment, waste/barrier/rock interactions, and barrier performance assessment provide the basis for selection of systems capable of meeting licensing requirements. Work has concentrated on specifying and testing natural and man-made materials which can be used to plug boreholes in basalt and which can be used as multiple barriers to surround nuclear waste forms and containers. The Engineered Barriers Program is divided into two major activities: multiple barrier studies and borehole plugging. 8 figures, 4 tables

  2. Montmorillonite Nanoparticles

    Directory of Open Access Journals (Sweden)

    H. Almasi

    2009-12-01

    Full Text Available Novel citric acid modified starch-carboxy methyl cellulose (CMC -montmorillonite (MMT bionanocomposite films were prepared by casting method and the effect of MMT on the structural and physical properties of the starch-CMC biocomposites was studied. X-ray diffraction test showed thatstrong polar interactions between the hydroxyl groups present in the starch and CMC chains and in the silicate layers led to intercalation of biopolymer chains into MMT layers galleries. The water vapor permeability decreased from 2.44 to 1.13×10-7 g/mhPa as the MMT percentage increased from0 to 7%. At the level of 7% MMT, the composite films showed the highest ultimate tensile strength (27.55 MPa and lowest strain-to-break (18.25%. The DSC tests showed that, the temperature position of the melting peak increased from 221.5°C to 243.0°C as MMT content increased from 1 to 7%, but the glass transition decreased and gradually disappeared.

  3. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    R. Jarek

    2005-08-29

    The purpose of this model report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The resulting seepage evaporation and gas abstraction models are used in the total system performance assessment for the license application (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2005 [DIRS 173782], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports. To be consistent with other project documents that address features, events, and processes (FEPs), Table 6.14.1 of the current report includes updates to FEP numbers and FEP subjects for two FEPs identified in the technical work plan (TWP) governing this report (BSC 2005 [DIRS 173782]). FEP 2.1.09.06.0A (Reduction-oxidation potential in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.06.0B (Reduction-oxidation potential in Drifts; see Table 6.14-1). FEP 2.1.09.07.0A (Reaction kinetics in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.07.0B (Reaction kinetics in Drifts; see Table 6.14-1). These deviations from the TWP are justified because they improve integration with FEPs

  4. ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

    International Nuclear Information System (INIS)

    R. Jarek

    2005-01-01

    The purpose of this model report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The resulting seepage evaporation and gas abstraction models are used in the total system performance assessment for the license application (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2005 [DIRS 173782], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports. To be consistent with other project documents that address features, events, and processes (FEPs), Table 6.14.1 of the current report includes updates to FEP numbers and FEP subjects for two FEPs identified in the technical work plan (TWP) governing this report (BSC 2005 [DIRS 173782]). FEP 2.1.09.06.0A (Reduction-oxidation potential in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.06.0B (Reduction-oxidation potential in Drifts; see Table 6.14-1). FEP 2.1.09.07.0A (Reaction kinetics in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.07.0B (Reaction kinetics in Drifts; see Table 6.14-1). These deviations from the TWP are justified because they improve integration with FEPs documents. The updates

  5. Influence of γ-radiation on the reactivity of montmorillonite towards H2O2

    International Nuclear Information System (INIS)

    Holmboe, Michael; Jonsson, Mats; Wold, Susanna

    2012-01-01

    Compacted and water saturated bentonite will be used as an engineered barrier in deep geological repositories for radioactive waste in many countries. Due to the high dose rate of ionizing radiation outside the canisters holding the nuclear waste, radiolysis of the interlayer and pore water in the compacted bentonite is unavoidable. Upon reaction with the oxidizing and reducing species formed by water radiolysis (OH • , e − (aq) , H • , H 2 O 2 , H 2 , HO 2 • , H 3 O + ), the overall redox properties in the bentonite barrier may change. In this study the influence of γ-radiation on the structural Fe(II)/Fe Tot ratio in montmorillonite and its reactivity towards hydrogen peroxide (H 2 O 2 ) was investigated in parallel experiments. The results show that under anoxic conditions the structural Fe(II)/Fe Tot ratio of dispersed Montmorillonite increased from ≤3 to 25–30% after γ-doses comparable to repository conditions. Furthermore, a strong correlation between the structural Fe(II)/Fe Tot ratio and the H 2 O 2 decomposition rate in montmorillonite dispersions was found. This correlation was further verified in experiments with consecutive H 2 O 2 additions, since the structural Fe(II)/Fe Tot ratio was seen to decrease concordantly. This work shows that the structural iron in montmorillonite could be a sink for one of the major oxidants formed upon water radiolysis in the bentonite barrier, H 2 O 2 .

  6. Montmorillonite stability under near-field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Leupin, O.X. (ed.); Birgersson, M.; Karnland, O. [Clay Technology AB, Lund (Sweden); Korkeakoski, P. [Posiva Oy, Eurajoki (Finland); Sellin, P. [Svensk Kärnbränslehantering AB, SKB, Stockholm (USSR); Mäder, U.; Wersin, P. [University of Berne, Berne (Switzerland)

    2014-07-15

    Clay-based engineered barriers comprising bentonite and bentonite/sand mixtures are the favoured option in geological repositories for high-level waste due to their inherently low hydraulic conductivity at full saturation. This ensures that diffusion of solutes such as radionuclides will be the dominating mechanism for transport through the engineered barriers. Another advantageous property of bentonite is the development of swelling pressure in contact with water under the constant volume conditions of repository excavations, ensuring the closure of unintentional gaps or openings. The predictability of the long-term behaviour of bentonite (up to a million years) is thus key to the safety analysis. The thermal pulse from the radioactive decay of the radionuclides in the high-level waste and spent fuel will lead to temperatures significantly higher than in the undisturbed host rock for hundreds of years, which may influence the thermodynamic stability and kinetics of alteration reactions of montmorillonite, the smectite that is the main constituent of the bentonite. The aim of this report is to review the present understanding of potential alteration of bentonite by focusing on experimental and modeling results under the thermal conditions of a repository. Many studies show that the transformation of smectite-to-illite is induced by increasing temperature and potassium activity. The conversion process is complex and still not completely understood. Nonetheless, it displays very slow kinetics over a wide range of environmental conditions for the temperatures of interest. The various models for illitisation of smectites suggest negligible transformation in a repository due to the relatively short period of elevated temperatures and slow mass transport. However, because of uncertainties and a number of conservatisms in the application of such models, the results of such calculations should be considered as bounding and indicative and not as quantitative predictions. In

  7. Montmorillonite stability under near-field conditions

    International Nuclear Information System (INIS)

    Leupin, O.X.; Korkeakoski, P.; Sellin, P.; Mäder, U.; Wersin, P.

    2014-07-01

    Clay-based engineered barriers comprising bentonite and bentonite/sand mixtures are the favoured option in geological repositories for high-level waste due to their inherently low hydraulic conductivity at full saturation. This ensures that diffusion of solutes such as radionuclides will be the dominating mechanism for transport through the engineered barriers. Another advantageous property of bentonite is the development of swelling pressure in contact with water under the constant volume conditions of repository excavations, ensuring the closure of unintentional gaps or openings. The predictability of the long-term behaviour of bentonite (up to a million years) is thus key to the safety analysis. The thermal pulse from the radioactive decay of the radionuclides in the high-level waste and spent fuel will lead to temperatures significantly higher than in the undisturbed host rock for hundreds of years, which may influence the thermodynamic stability and kinetics of alteration reactions of montmorillonite, the smectite that is the main constituent of the bentonite. The aim of this report is to review the present understanding of potential alteration of bentonite by focusing on experimental and modeling results under the thermal conditions of a repository. Many studies show that the transformation of smectite-to-illite is induced by increasing temperature and potassium activity. The conversion process is complex and still not completely understood. Nonetheless, it displays very slow kinetics over a wide range of environmental conditions for the temperatures of interest. The various models for illitisation of smectites suggest negligible transformation in a repository due to the relatively short period of elevated temperatures and slow mass transport. However, because of uncertainties and a number of conservatisms in the application of such models, the results of such calculations should be considered as bounding and indicative and not as quantitative predictions. In

  8. International Collaboration Activities on Engineered Barrier Systems

    Energy Technology Data Exchange (ETDEWEB)

    Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-08-31

    The Used Fuel Disposition Campaign (UFDC) within the DOE Fuel Cycle Technologies (FCT) program has been engaging in international collaborations between repository R&D programs for high-level waste (HLW) disposal to leverage on gathered knowledge and laboratory/field data of near- and far-field processes from experiments at underground research laboratories (URL). Heater test experiments at URLs provide a unique opportunity to mimetically study the thermal effects of heat-generating nuclear waste in subsurface repository environments. Various configurations of these experiments have been carried out at various URLs according to the disposal design concepts of the hosting country repository program. The FEBEX (Full-scale Engineered Barrier Experiment in Crystalline Host Rock) project is a large-scale heater test experiment originated by the Spanish radioactive waste management agency (Empresa Nacional de Residuos Radiactivos S.A. – ENRESA) at the Grimsel Test Site (GTS) URL in Switzerland. The project was subsequently managed by CIEMAT. FEBEX-DP is a concerted effort of various international partners working on the evaluation of sensor data and characterization of samples obtained during the course of this field test and subsequent dismantling. The main purpose of these field-scale experiments is to evaluate feasibility for creation of an engineered barrier system (EBS) with a horizontal configuration according to the Spanish concept of deep geological disposal of high-level radioactive waste in crystalline rock. Another key aspect of this project is to improve the knowledge of coupled processes such as thermal-hydro-mechanical (THM) and thermal-hydro-chemical (THC) operating in the near-field environment. The focus of these is on model development and validation of predictions through model implementation in computational tools to simulate coupled THM and THC processes.

  9. Engineered barriers for radioactive waste confinement

    Directory of Open Access Journals (Sweden)

    Fernández, R.

    2011-09-01

    Full Text Available Nuclear power plants generate long-lived radioactive waste of high toxicity. The security assessment of repositories destined to definitive confinement of radioactive waste has been studied for several decades. Deep geological repositories are technically feasible and begin to be built by some pioneer countries. The scientific evaluation of interactions between the different engineered barriers is studied by laboratory experiments, natural analogues and modeling studies. The three methods are able to represent and validate the main geochemical processes that take place in the near field. This paper reviews the scientific and technical basis of the concept of geological disposal, with particular focus on the methods of study applied to the evaluation of geochemical stability of the bentonite barrier.

    Las centrales nucleares generan residuos radiactivos de elevada peligrosidad y permanencia en el tiempo. La evaluación de la seguridad de repositorios destinados al alojamiento definitivo de estos residuos lleva estudiándose desde hace varias décadas. El almacenamiento geológico es técnicamente factible y empieza ya a desarrollarse en países pioneros. La evaluación científica de las interacciones entre las distintas barreras de ingeniería se estudia mediante ensayos de laboratorio, análisis de análogos naturales y modelos teóricos. Las tres vías de estudio son capaces de representar y validar los principales procesos geoquímicos que tienen lugar en el campo cercano al repositorio. Este artículo revisa los fundamentos científicos y técnicos del concepto de almacenamiento geológico detallando, en particular, los métodos de estudio aplicados a la evaluación de la estabilidad geoquímica de la barrera de bentonita.

  10. Validation of the Performance of Engineered Barriers

    International Nuclear Information System (INIS)

    Choi, Jongwon; Cho, Wonjin; Kwon, Sangki

    2012-04-01

    To study the thermal-hydro-mechanical (THM) and thermal-hydro-mechanical-chemical (THMC) behavior of engineered barrier system (EBS), the engineering scale experiments, KENTEX and KENTEX-C were conducted to investigate THM and THMC behavior in the buffer. The computer modelling and simulation programmes were developed to analyze the distribution of temperature, water content, total pressure and the measured data on the migration behavior of anion and cation. In-situ heater test were performed to investigate the effect of the ventilation, thermal characteristics of EDZ, and effect of the anisotropy of rock mass and joint in addition to the investigation of the thermo-mechanical behavior in rock mass. The geophysics exploration and in-situ field tests were carried out to investigate the range of EDZ and its effects on the mechanical properties of rock. Subsequently, crack propagation characteristics and dynamic material properties of jointed rock mass in KURT were measured. Concurrently, the in-situ experiments were performed in the KURT to investigate the change of hydraulic properties in EDZ. The stainless steel molds are manufactured to fabricate the buffer blocks with various shapes. The experiments are carried out to check the mechanical properties, the workability for installation of the fabricated blocks and to investigate the resaturation processes. The state of the technology on application of cementitious materials to the HLW repository was analysed and the optimized low-pH cement recipe was obtained. And the material properties of low-pH and high-pH cement grouts were evaluated based on the grout recipes of ONKALO in Finland. The KURT was operated, and the various technical supports were provided to the in-situ experiments which were carried at KURT

  11. Prototype Engineered Barrier System Field Tests (PEBSFT)

    International Nuclear Information System (INIS)

    Ramirez, A.L.; Wilder, D.G.

    1991-02-01

    This progress report presents the interpretation of data obtained (up to November 1, 1988) from the Prototype Engineered Barrier System Field Tests (PEBSFT) that are being performed for the Yucca Mountain Project (YMP) in G-Tunnel within the Nevada Test site. The PEBSFTs are being conducted to evaluate the applicability of measurement techniques, numerical models, and procedures developed for the field tests for future investigations that will be conducted in the Exploratory Shaft Facilities, at a potential high-level radioactive waste repository site in Yucca Mountain. The primary objective of the tests is to provide the basis for determining whether tests planned for Yucca Mountain have the potential to be successful. Thirteen chapters discuss the following: mapping the electromagnetic permittivity and attenuation rate of the rock mass; changes in moisture content detected by the neutron logging probe; characterization of the in-situ permeability of the fractured tuff around the heater borehole; electrical resistance heater installed in a 30-cm borehole; relative humidity measurements; the operation, design, construction, calibration, and installation of a microwave circuit that might provide partial pressure information at temperatures in excess of 200 degree C (392 degree F); pressure and temperature measurements in the G-Tunnel; the moisture collection system, which attempts to collect steam that migrates into the heater borehole; The borehole television and borescope surveys that were performed to map the location, orientation, and aperture of the fractures intersecting the boreholes; preliminary scoping calculations of the hydrothermal conditions expected for this prototype test; the Data Acquisition System; and the results of the PEBSFT, preliminary interpretations of these results, and plans for the remainder of the test. Chapters have been indexed separately for inclusion on the data base

  12. Prototype Engineered Barrier System Field Test (PEBSFT)

    International Nuclear Information System (INIS)

    Ramirez, A.L.; Buscheck, T.; Carlson, R.; Daily, W.; Lee, K.; Lin, Wunan; Mao, Nai-hsien; Ueng, Tzou-Shin; Wang, H.; Watwood, D.

    1991-08-01

    This final report represents a summary of data and interpretations obtained from the Prototype Engineered Barrier System Field Test (PEBSFT) performed in G-Tunnel within the Nevada Test Site. The PEBSFT was conducted to evaluate the applicability of measurement techniques, numerical models, and procedures developed for future field tests that will be conducted in the Exploratory Studies Facilities (ESF) at Yucca Mountain. The primary objective of the test was to provide a basis for determining whether tests planned for the ESF have the potential to be successful. Chapter 1 on high frequency electromagnetic tomography discusses the rock mass electromagnetic permittivity and attenuation rate changes that were measured to characterize the water distribution in the near field of a simulated waste container. The data are used to obtain quantitative estimates of how the moisture content in the rock mass changes during heating and to infer properties of the spatial variability of water distribution, leading to conclusions about the role of fractures in the system. Chapter 2 discusses the changes in rock moisture content detected by the neutron logging probe. Chapter 3 permeability tests discusses the characterization of the in-situ permeability of the fractured tuff around the borehole. The air permeability testing apparatus, the testing procedures, and the data analysis are presented. Chapter 4 describes the moisture collection system installed in the heater borehole to trap and measure the moisture volumes. Chapter 5 describes relative humidity measurements made with the thermocouple psychrometer and capacitance sensors. Chapter 6 discusses gas pressure measurements in the G-Tunnel, addressing the calibration and installation of piezoresistive-gaged transducers. Chapter 7 describes the calibration and installation of thermocouples for temperature measurements. Chapter 8 discusses the results of the PEBSFT

  13. Engineered Barrier Testing at the INEEL Engineered Barriers Test Facility: FY-1997 and FY-1998

    International Nuclear Information System (INIS)

    Keck, K. N.; Porro, I.

    1998-01-01

    Engineered barriers of two designs are being tested at the Engineered Barriers Test Facility (EBTF) at the Idaho National Engineering and Environmental Laboratory. This report describes the test facility, barrier designs, and instruments used to monitor the test plots. Wetting tests conducted on the test plots in FY-97 are described and data collected from monitoring the test plots before, during and after the wetting tests are used to evaluate the performance of the covers during FY-97 and FY-98. Replicates of two engineered barrier designs were constructed in the EBTF cells. The first design comprises a thick, vegetated soil cover. The second design incorporates a capillary/biobarrier within the vegtated soil cover. The capillary barrier uses the textural break between an upper, fine textured soil and a lower, coarser-textured gravel layer to inhibit drainage under unsaturated conditions while increasing soil moisture storage in the root zone. Evaporation and transpiration by plants (although the test plots have not yet been vegetated) are used to recycle water stored in the soil back to the atmosphere. A geotextile fabric is used to maintain separation of the soil and gravel layers. A thick layer of cobbles beneath the gravel layer serves as a biobarrier to prevent intrusion of plant roots and burrowing animals into underlying waste (there is no waste in the test plots). Each test plot was instrumented with time domain reflectometry probes and neutron probe access tubes to measure moisture contents, tensiometers, heat dissipation sensors, and thermocouple psychrometers to measure matric potentials, thermocouples to measure soil temperature, and ion-exchange resin beads to monitor tracer movement. Each drainage sump is equipped with a tipping bucket instrument and pressure transducer to measure drainage. Precipitation is measured using a heated rain gauge located at the EBTF. Instrument calibration equation coefficients are presented, and data reduction

  14. Improved Barriers to Turbine Engine Fragments: Interim Report II

    National Research Council Canada - National Science Library

    Shockey, Donald

    1999-01-01

    ... the effects of uncontained engine bursts. SRI International is evaluating the ballistic effectiveness of fabric structures made from advanced polymers and developing a computational ability to design fragment barriers...

  15. ENGINEERED BARRIER SYSTEM FEATURES, EVENTS AND PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Jaros, W.

    2005-08-30

    The purpose of this report is to evaluate and document the inclusion or exclusion of engineered barrier system (EBS) features, events, and processes (FEPs) with respect to models and analyses used to support the total system performance assessment for the license application (TSPA-LA). A screening decision, either Included or Excluded, is given for each FEP along with the technical basis for exclusion screening decisions. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.114 (d, e, and f) [DIRS 173273]. The FEPs addressed in this report deal with those features, events, and processes relevant to the EBS focusing mainly on those components and conditions exterior to the waste package and within the rock mass surrounding emplacement drifts. The components of the EBS are the drip shield, waste package, waste form, cladding, emplacement pallet, emplacement drift excavated opening (also referred to as drift opening in this report), and invert. FEPs specific to the waste package, cladding, and drip shield are addressed in separate FEP reports: for example, ''Screening of Features, Events, and Processes in Drip Shield and Waste Package Degradation'' (BSC 2005 [DIRS 174995]), ''Clad Degradation--FEPs Screening Arguments (BSC 2004 [DIRS 170019]), and Waste-Form Features, Events, and Processes'' (BSC 2004 [DIRS 170020]). For included FEPs, this report summarizes the implementation of the FEP in the TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded). This report also documents changes to the EBS FEPs list that have occurred since the previous versions of this report. These changes have resulted due to a reevaluation of the FEPs for TSPA-LA as identified in Section 1.2 of this report and described in more detail in Section 6.1.1. This revision addresses updates in Yucca Mountain Project

  16. ENGINEERED BARRIER SYSTEM FEATURES, EVENTS AND PROCESSES

    International Nuclear Information System (INIS)

    Jaros, W.

    2005-01-01

    The purpose of this report is to evaluate and document the inclusion or exclusion of engineered barrier system (EBS) features, events, and processes (FEPs) with respect to models and analyses used to support the total system performance assessment for the license application (TSPA-LA). A screening decision, either Included or Excluded, is given for each FEP along with the technical basis for exclusion screening decisions. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.114 (d, e, and f) [DIRS 173273]. The FEPs addressed in this report deal with those features, events, and processes relevant to the EBS focusing mainly on those components and conditions exterior to the waste package and within the rock mass surrounding emplacement drifts. The components of the EBS are the drip shield, waste package, waste form, cladding, emplacement pallet, emplacement drift excavated opening (also referred to as drift opening in this report), and invert. FEPs specific to the waste package, cladding, and drip shield are addressed in separate FEP reports: for example, ''Screening of Features, Events, and Processes in Drip Shield and Waste Package Degradation'' (BSC 2005 [DIRS 174995]), ''Clad Degradation--FEPs Screening Arguments (BSC 2004 [DIRS 170019]), and Waste-Form Features, Events, and Processes'' (BSC 2004 [DIRS 170020]). For included FEPs, this report summarizes the implementation of the FEP in the TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded). This report also documents changes to the EBS FEPs list that have occurred since the previous versions of this report. These changes have resulted due to a reevaluation of the FEPs for TSPA-LA as identified in Section 1.2 of this report and described in more detail in Section 6.1.1. This revision addresses updates in Yucca Mountain Project (YMP) administrative procedures as they

  17. Study on vibration behaviors of engineered barrier system

    International Nuclear Information System (INIS)

    Mikoshiba, Tadashi; Ogawa, Nobuyuki; Minowa, Chikahiro

    1998-01-01

    High-level radioactive wastes have been buried underground by packing into a strong sealed container made from carbon steel (over-pack) with buffer material (bentonite). The engineered barrier system constructed with an overpack and buffer materials must be resistant to earthquakes as well as invasion of groundwater for a long period. Therefore, seismic evaluation of barrier system for earthquakes is indispensable especially in Japan to keep its structural safety. Here, the effects of earthquake vibration on the engineered barrier systems were investigated experimentally. Random-wave vibration and practical seismic wave one were loaded for the systems and fundamental data were obtained. For the former vibration the response characteristics of both engineered barrier models constructed with overpack and bentonite were non-linear. For the latter one, the stress in bentonite was increased in proportion to the vibration level. (M.N.)

  18. Engineered barrier systems (EBS): design requirements and constraints

    International Nuclear Information System (INIS)

    2004-01-01

    A joint NEA-EC workshop entitled 'Engineered Barrier Systems: Design Requirements and Constraints' was organised in Turku, Finland on 26-29 August 2003 and hosted by Posiva Oy. The main objectives of the workshop were to promote interaction and collaboration among experts responsible for engineering design and safety assessment in order to develop a greater understanding of how to achieve the integration needed for the successful design of engineered barrier systems, and to clarify the role that an EBS can play in the overall safety case for a repository. These proceedings present the outcomes of this workshop. (author)

  19. FACTORS AFFECTING PERFORMANCE OF ENGINEERED BARRIERS

    International Nuclear Information System (INIS)

    J.A. BLINK, R.W. ANDREWS, J.N. BAILEY, T.W. DOERING J.H. LEE, J.K. MCCOY, D.G. MCKENZIE, D. SEVOUGIAN AND V. VALLIKAT

    1998-01-01

    For the Yucca Mountain Viability Assessment (VA), a reference design was tentatively selected in September 1997, and a series of model abstractions are being prepared for the performance assessment (PA) of that design. To determine the sensitivity of peak dose rate at the accessible environment to engineered components, several design options were subjected to the PA models available late in FY97

  20. Physico-chemical impacts of cementitiously-derived calcium and silica on sodium montmorillonite

    International Nuclear Information System (INIS)

    Kinsela, Andrew S.; Tjitradjaja, Alice; Collins, Richard N.; Waite, T. David; Macdonald, Bennett C.T.; White, Ian; PAYNE, Timothy E.

    2012-01-01

    The storage of nuclear waste frequently involves the construction of a concrete encasement adjacent to an engineered clay barrier, which can expose the swelling clay to elevated concentrations of certain cations (particularly calcium) and very high alkalinity (pH 10 - 13). These conditions have the capacity to degrade the integrity of the clay layer and, as such, it is necessary to fully understand the effects of all possible biogeochemical interactions involved. In this study, the changes in hydraulic conductivities and other physico-chemical properties of Na-montmorillonite assemblages under the influence of both highly alkaline (pH 9 and 12) conditions and elevated concentrations of calcium and silica are examined. The Na-montmorillonite suspensions and filtration experimental method is presented, as well as the electrophoresis characterization technique

  1. Alternative approaches to reliability modeling of a multiple engineered barrier system

    International Nuclear Information System (INIS)

    Ananda, M.M.A.; Singh, A.K.

    1994-01-01

    The lifetime of the engineered barrier system used for containment of high-level radioactive waste will significantly impact the total performance of a geological repository facility. Currently two types of designs are under consideration for an engineered barrier system, single engineered barrier system and multiple engineered barrier system. Multiple engineered barrier system consists of several metal barriers and the waste form (cladding). Some recent work show that a significant improvement of performance can be achieved by utilizing multiple engineered barrier systems. Considering sequential failures for each barrier, we model the reliability of the multiple engineered barrier system. Weibull and exponential lifetime distributions are used through out the analysis. Furthermore, the number of failed engineered barrier systems in a repository at a given time is modeled using a poisson approximation

  2. Performance of engineered barriers for low-level waste

    International Nuclear Information System (INIS)

    Taplin, D.; Claridge, F.B.

    1987-09-01

    Geotechnical Resources Ltd., in association with Komex Consultants Ltd., was retained to collect, synthesize and evaluate the available information on the long term performance of engineered barriers for low-level radioactive wastes disposed in Canada. Literature was researched from Canadian, United States and European sources. A variety of barrier materials were assessed in the study and included natural clays, concrete and cement, metals, bentonite-sand admixes, bitumen and bituminous admixes, soil cement and polymeric membranes. The generalized geological and geotechnical conditions encountered within the soil and rock host media currently under consideration for disposal sites in southern Ontario were also summarized. Both internal barriers, or buffers, to immobilize the waste material and reduce radionuclide mobility, as well as external barriers to limit the migration of contaminants were examined. Microbial activities within the waste forms were analyzed, including cellulose degradation, methanogenesis and bicarbonate and organic reactions. Microbial interactions with the various engineered barrier materials under consideration were also assessed. Finally, the anticipated long term performances of the respective barrier materials under consideration were evaluated, along with the general suitability of the geological host media being proposed for disposal sites

  3. The role of engineered barriers in spent fuel disposal

    International Nuclear Information System (INIS)

    Vokal, A.

    1997-01-01

    Engineered, i.e. man-made, barriers in underground spent fuel disposal include the waste form itself, the fuel cladding, the storage container, and the isolating system made of buffering, filling, and sealing materials. The parameters of and requirements for each of the components are highlighted, and the methodology of materials selection is discussed. (P.A.)

  4. Engineered Barrier System: Physical and Chemical Environment Model

    International Nuclear Information System (INIS)

    Jolley, D. M.; Jarek, R.; Mariner, P.

    2004-01-01

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

  5. Engineered barrier experiment. Power control and data acquisition systems

    International Nuclear Information System (INIS)

    Alberdi, J.; Barcala, J.M.; Gamero, E.; Martin, P.L.; Molinero, A.; Navarrete, J.J.; Yuste, C.

    1997-01-01

    The engineered barrier concept for the storage of radioactive wastes is being tested at almost full scale at CIEMAT facilities. A data acquisition and control is an element of this experiment. This system would be operating for next three years. (Author)

  6. The Blood-Brain Barrier: An Engineering Perspective

    Directory of Open Access Journals (Sweden)

    Andrew eWong

    2013-08-01

    Full Text Available It has been more than 100 years since Paul Ehrlich reported that various water-soluble dyes injected into the circulation did not enter the brain. Since Ehrlich’s first experiments, only a small number of molecules, such as alcohol and caffeine have been found to cross the blood-brain barrier, and it remains the major roadblock to treatment of many central nervous system diseases. At the same time, many central nervous system diseases are associated with disruption of the blood-brain barrier that can lead to changes in permeability, modulation of immune cell transport, and trafficking of pathogens into the brain. Therefore advances in our understanding of the structure and function of the blood-brain barrier are key to advances in treatment of a wide range of central nervous system diseases. Over the past 10 years it has become recognized that the blood-brain barrier is a complex dynamic system that involves biomechanical and biochemical signaling between the vascular system and the brain. Here we reconstruct the structure, function, and transport properties of the blood-brain barrier from an engineering perspective. New insight into the physics of the blood-brain barrier could ultimately lead to clinical advances in the treatment of central nervous system diseases.

  7. Diffusive Transport of Sulphide through an Engineering Barrier System in a Deep Geological Repository

    Science.gov (United States)

    Briggs, S. A.; Sleep, B. E.; McKelvie, J. R. M.; Krol, M.

    2015-12-01

    Bentonite is a naturally occurring clay-rich sediment containing montmorillonite, a smectitic clay mineral that has a high cation exchange capacity and swells upon contact with water. Owing to these characteristics, highly compacted bentonite (HCB) is an often included component of engineered barrier systems (EBS) designed to protect used fuel containers (UFCs) in deep geological repositories (DGR) for high-level nuclear waste. The low water activity and high swelling pressure of HCB suppresses microbial activity and the related production of sulphide that could cause microbiologically influenced corrosion (MIC) of UFCs The Canadian Nuclear Waste Management Organization (NWMO) has chosen a UFC that consists of an inner steel core and outer copper coating which is resistant to corrosion. However, under anaerobic conditions, MIC can still contribute to UFC corrosion if sulphides are present in the groundwater. Therefore the EBS consisting of bentonite blocks and pellets has been designed to impede the movement of sulphides to the UFC. In order to examine the effectiveness of the EBS, a 3D numerical model was developed capable of simulating the diffusive transport of sulphide within the NWMO EBS. The model was developed using COMSOL Multiphysics, a finite element software package and is parametric which allows the impact of different repository layouts to be assessed. The developed model was of the entire NWMO placement room, as well as, a stand-alone UFC and included conservative assumptions such as a fully saturated system and a constant concentration boundary condition. The results showed that the highest sulphide flux occurred at the semi-spherical end caps of the UFC. Further studies examined the effect of sulphide hotspots and fractures, representing possible EBS failure mechanisms. The model results highlight that even with conservative assumptions the chosen EBS will effectively protect the UFC from microbiologically influenced corrosion.

  8. Review of durability of cementitious engineered barriers in repository environments

    International Nuclear Information System (INIS)

    Parrott, L.J.; Lawrence, C.D.

    1992-01-01

    This report is concerned with the durability of cementitious engineered barriers in a repository for low and intermediate level nuclear waste. Following the introduction the second section of the review identifies the environmental conditions associated with a deep, hard rock repository for ILW and LLW that are relevant to the durability of cementitious barriers. Section three examines the microstructure and macrostructure of cementitious materials and considers the physical and chemical processes of radionuclide immobilization. Potential repository applications and compositions of cementitious materials are reviewed in Section four. The main analysis of durability is dealt with in Section five. The different types of cementitious barrier are considered separately and their most probable modes of degradation are analysed. Concluding remarks that highlight critical technical matters are given in Section six. (author)

  9. Experimental Approach of Fault Movement on an Engineered Barrier System

    International Nuclear Information System (INIS)

    Lee, Minsoo; Choi, Heuijoo; Kim, Heuna

    2012-01-01

    Safety evaluation of an engineered barrier system against fault movement at underground disposal region for high level waste (HLW) is tried using a miniature bore-shear apparatus. For the purpose, a miniature bore-shear apparatus simulating an EBS (engineered barrier system) was manufactured in 1/30 scale. And using the developed apparatus, bore-shear tests were performed twice. During the tests, pressure variations were checked at 6 points around buffer zone, and then a rotational angle of the test vessel was checked. The achieved pressure data were compared with those from analytical modeling, which is based on Drucker-Prager model. At initial shearing step, high pressure was recorded at some point but it decreased rapidly. For the better understanding of fault movement, the modification of an analytical model and the accumulation of experimental experience were required

  10. Experimental Approach of Fault Movement on an Engineered Barrier System

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Minsoo; Choi, Heuijoo; Kim, Heuna [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-03-15

    Safety evaluation of an engineered barrier system against fault movement at underground disposal region for high level waste (HLW) is tried using a miniature bore-shear apparatus. For the purpose, a miniature bore-shear apparatus simulating an EBS (engineered barrier system) was manufactured in 1/30 scale. And using the developed apparatus, bore-shear tests were performed twice. During the tests, pressure variations were checked at 6 points around buffer zone, and then a rotational angle of the test vessel was checked. The achieved pressure data were compared with those from analytical modeling, which is based on Drucker-Prager model. At initial shearing step, high pressure was recorded at some point but it decreased rapidly. For the better understanding of fault movement, the modification of an analytical model and the accumulation of experimental experience were required.

  11. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    Andra organised an International Symposium on the use of Natural and Engineered Clay-based Barriers for the Containment of Radioactive Waste hold at the Congress Centre of Tours, France, in March 2005. The symposium provided an opportunity to take stock of the potential properties of the clay-based materials present in engineered or natural barriers in order to meet the containment specifications of a deep geological repository for radioactive waste. It was intended for specialists working in the various disciplines involved with clays and clay based minerals, as well as scientists from agencies and organisations dealing with investigations on the disposal of high-level and long-lived radioactive waste. The themes of the Symposium included geology, geochemistry, transfers of materials, alteration processes, geomechanics, as well as the recent developments regarding the characterisation of clays, as well as experiments in surface and underground laboratories. The symposium consisted of plenary sessions, parallel specialized sessions and poster sessions. (author)

  12. Integrated modelling of near field and engineered barrier system processes

    International Nuclear Information System (INIS)

    Lamont, A.; Gansemer, J.

    1994-01-01

    The Yucca Mountain Integrating Model (YMIM) is an integrated model of the Engineered barrier System has been developed to assist project managers at LLNL in identifying areas where research emphasis should be placed. The model was designed to be highly modular so that a model of an individual process could be easily modified or replaced without interfering with the models of other processes. The modules modelling container failure and the dissolution of nuclides include particularly detailed, temperature dependent models of their corresponding processes

  13. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  14. Engineered Barrier System: Physical and Chemical Environment Model

    Energy Technology Data Exchange (ETDEWEB)

    D. M. Jolley; R. Jarek; P. Mariner

    2004-02-09

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

  15. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    International Nuclear Information System (INIS)

    E.L. Hardin

    2000-01-01

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II)

  16. EFFECT OF ORGANOPHILIZATION AND INTERLAMELLAR SILYLATION OF MONTMORILLONITE ON COMPATIBLIZATION OF POLYMER COMPOSITES

    Directory of Open Access Journals (Sweden)

    Mamdouh Abdel Rahim

    2016-12-01

    Full Text Available Sodium montmorillonite (Na-Mt was modified by cetyltriemethylammoniumbromide (CTAB through cation exchange technique followed by grafting with 3-aminopropyltriethoxysilane (APT. The effects of organophillic surface treatments of montmorillonite on compatibilization of natural rubber (NR /acrylonitrile butadiene rubber (NBR blends was investigated. Physico-mechanical properties of rubber nanocomposites compatibilized with organomodified montmorillonite revealed strong nanocomposite with high tensile properties, impact strength and good resistance to flex fatigue, abrasion and compression set. Dynamic mechanical thermal analysis (DMTA revealed a marked increase in storage modulus (E' and lesser damping characteristics of organically modified clay mineral polymer nanocomposites (CPN due to intercalation of organophilic montmorillonite by rubber matrix. The morphology of the blends became homogeneous and smoother with the presence of exofoliated/intercalated organically modified montmorillonite. Organomodified layered silicate sheets of montmorillonite greatly enhanced barrier properties by creating tortuous path that retarded the progress of solvent molecules through rubber matrix.

  17. Chemical interaction of tetravalent actinides simulators and the engineering barrier

    International Nuclear Information System (INIS)

    Chain, Pablo; Alba, Maria D.; Castro, Miguel A.; Pavon, Esperanza; Mar Orta, M.

    2010-01-01

    Document available in extended abstract form only. The Deep Geological Repository (DGR) is the most internationally accepted option for the storage of high radioactive wastes. This confinement is based on the Multi-barrier Concept where the engineered barrier is a crucial safety wise. Nowadays, bentonite is accepted as the best argillaceous material in the engineered barrier of DGR. Additionally to its well-known physical role, a chemical interaction between lutetium, as actinide simulator, and the smectite has been demonstrated. The existence of a reaction mechanism, which was not previously described, based on the chemical interaction between the lanthanide cations and the orthosilicate anions of the lamellar structure has been identified. This finding has aroused the interest of the scientific community because lanthanides are used as simulators of high activity radionuclide (HAR) in agreement with the guidelines established in the bibliography. It has been observed that in conditions of moderate temperature and pressure a chemical interaction exists between smectites and rare earth elements (RE) and phases of insoluble di-silicate, RE 2 Si 2 O 7 , which would immobilize RE, are generated. It is remarkable that the reaction extends to all the set of the smectites, although they do not display the same reactivity, the saponite being the most reactive. The main isotopes present in the HLW belong to the actinide elements Np, Pu, Am and Cm, in addition to uranium generated by neutron capture during the fuel combustion process. The study of the mobilization of actinide (IV) thorough the bentonite barrier is limited because of their radioactivity. However, U(IV), Np(IV), Pu(IV) and Th(IV) can be simulated by the stable isotopes of the Zr(IV) and Hf(IV), because they exhibit ionic radius and physicochemical properties very similar to those of the actinide elements. It is the main objective of this research to investigate the chemical interaction of Zr(IV) as actinide

  18. Engineered sorbent barriers for low-level waste disposal

    International Nuclear Information System (INIS)

    Mitchell, S.J.; Freeman, H.D.; Buelt, J.L.

    1987-01-01

    The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is developing sorbent materials to prevent the migration of radionuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Screening studies identified promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite of clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent, adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 2 references, 6 figures, 3 tables

  19. Engineered sorbent barriers for low-level waste disposal.

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, H.D.; Mitchell, S.J.; Buelt, J.L.

    1986-12-01

    The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is investigating sorbent materials to prevent the migration of soluble radio nuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Laboratory studies identifield promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent and was adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and local soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow-land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 7 refs., 14 figs., 12 tabs.

  20. Engineered sorbent barriers for low-level waste disposal

    International Nuclear Information System (INIS)

    Freeman, H.D.; Mitchell, S.J.; Buelt, J.L.

    1986-12-01

    The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is investigating sorbent materials to prevent the migration of soluble radio nuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Laboratory studies identifield promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent and was adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and local soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow-land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 7 refs., 14 figs., 12 tabs

  1. Materials characterization center workshop on corrosion of engineered barriers

    Energy Technology Data Exchange (ETDEWEB)

    Merz, M.D.; Zima, G.E.; Jones, R.H.; Westerman, R.E.

    1981-03-01

    A workshop on corrosion test procedures for materials to be used as barriers in nuclear waste repositories was conducted August 19 and 20, 1980, at the Battelle Seattle Research Center. The purpose of the meeting was to obtain guidance for the Materials Characterization Center in preparing test procedures to be approved by the Materials Review Board. The workshop identified test procedures that address failure modes of uniform corrosion, pitting and crevice corrosion, stress corrosion, and hydrogen effects that can cause delayed failures. The principal areas that will require further consideration beyond current engineering practices involve the analyses of pitting, crevice corrosion, and stress corrosion, especially with respect to quantitative predictions of the lifetime of barriers. Special techniques involving accelerated corrosion testing for uniform attack will require development.

  2. Yucca Mountain engineered barrier system corrosion model (EBSCOM)

    International Nuclear Information System (INIS)

    King, F.; Kolar, M.; Kessler, J.H.; Apted, M.

    2008-01-01

    A revised engineered barrier system model has been developed by the Electric Power Research Institute to predict the time dependence of the failure of the drip shields and waste packages in the proposed Yucca Mountain repository. The revised model is based on new information on various corrosion processes developed by the US Department of Energy and others and for a 20-mm-thick waste package design with a double closure lid system. As with earlier versions of the corrosion model, the new EBSCOM code produces a best-estimate of the failure times of the various barriers. The model predicts that only 15% of waste packages will fail within a period of 1 million years. The times for the first corrosion failures are 40,000 years, 336,000 years, and 375,000 years for the drip shield, waste package, and combination of drip shield and the associated waste package, respectively

  3. Materials characterization center workshop on corrosion of engineered barriers

    International Nuclear Information System (INIS)

    Merz, M.D.; Zima, G.E.; Jones, R.H.; Westerman, R.E.

    1981-03-01

    A workshop on corrosion test procedures for materials to be used as barriers in nuclear waste repositories was conducted August 19 and 20, 1980, at the Battelle Seattle Research Center. The purpose of the meeting was to obtain guidance for the Materials Characterization Center in preparing test procedures to be approved by the Materials Review Board. The workshop identified test procedures that address failure modes of uniform corrosion, pitting and crevice corrosion, stress corrosion, and hydrogen effects that can cause delayed failures. The principal areas that will require further consideration beyond current engineering practices involve the analyses of pitting, crevice corrosion, and stress corrosion, especially with respect to quantitative predictions of the lifetime of barriers. Special techniques involving accelerated corrosion testing for uniform attack will require development

  4. Hydrothermal effects on montmorillonite

    International Nuclear Information System (INIS)

    Pusch, R.; Karnland, O.

    1988-06-01

    Hydrothermal effects on montmorillonite clay are usually taken to have the form of conversion of this clay mineral to other species, such as illite, disregarding microstructural alteration and cementation caused by precipitation of silica and other compounds. The report is focussed on identification of the primary processes that are involved in such alteration, the release of silica and the microstructural changes associated with heating being of major interest. In the first test phase, Na montmorillonite in distilled water was investigated by XRD, rheology tests and electron microscopy after heating to 60-225 0 C for 0.01 to 1 year. The preliminary conclusions are that heating produces contraction of the particle network to form dense 'branches', the effect being most obvious at the highest temperature but of significance even at 60-100 0 C. Release of substantial amounts of silica gas been documented for temperatures exceeding 150 0 and precipitation of silica was observed on cooling after the hydrothermal testing under the closed conditions that prevailed throughout the tests. The precipitates, which appeared to be amorphous and probably consisted of hydrous silica gels, were concluded to have increased the mechanical strength and caused some brittleness, particularly of the dense clays. The nature of the silica release, which is assumed to be associated with beidellitization, may be closely related to an unstable state of a certain fraction of tetrahedral silica at heat-inducted transfer between two different crystal modes of montmorillonite. (orig.)

  5. Study on vibration behaviors of engineered barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Mikoshiba, Tadashi; Ogawa, Nobuyuki; Minowa, Chikahiro [National Research Inst. for Earth Science and Disaster Prevention, Tsukuba, Ibaraki (Japan)

    1999-02-01

    Small engineered barrier model was mode and tested by vibrating with the random wave and the real earthquake wave. The wave observed at Kamaishi (N-S, N-W), Iwate Prefecture, in September 6, 1993, and Kobe (N-S) etc. were used as the real earthquake waves. The trial overpack showed non-linear characteristics (soft spring) by vibrating with the random wave. The pressure and acceleration of trial overpack and constraint container increased with increasing the vibration level of the real earthquake wave. The trial overpack moved the maximum 1.7 mm of displacement and 16 mm subsidence. The results showed both waves rocked the trialpack. (S.Y.)

  6. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system

    International Nuclear Information System (INIS)

    Marty, N.

    2006-11-01

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  7. Scientific investigation plan for initial engineered barrier system field tests

    International Nuclear Information System (INIS)

    Wunan Lin.

    1993-02-01

    The purpose of this Scientific Investigation Plan (SIP) is to describe tests known as Initial Engineered Barrier System Field Tests (IEBSFT) and identified by Work Breakdown Structure as WBS 1.2.2.2.4. The IEBSFT are precursors to the Engineered Barrier System Field Test (EBSFT), WBS 1.2.2.2.4, to be conducted in the Exploratory Study Facility (ESF) at Yucca Mountain. The EBSFT and IEBSFT are designed to provide information on the interaction between waste packages (simulated by heated containers) and the surrounding rock mass, its vadose water, and infiltrated water. Heater assemblies will be installed in drifts or boreholes openings and heated to measure moisture movement during heat-up and subsequent cool-down of the rock mass. In some of the tests, infiltration of water into the heated rock mass will be studied. Throughout the heating and cooling cycle, instruments installed in the rock will monitor such parameters as temperature, moisture content, concentration of some chemical species, and stress and strain. Rock permeability measurements, rock and fluid (water and gas) sampling, and fracture pattern measurements will also be made before and after the test

  8. The disposal of Canada's nuclear fuel waste: engineered barriers alternatives

    International Nuclear Information System (INIS)

    Johnson, L.H.; Tait, J.C.; Shoesmith, D.W.; Crosthwaite, J.L.; Gray, M.N.

    1994-01-01

    The concept for disposal of Canada's nuclear fuel waste involves emplacing the waste in a vault excavated at a depth of 500 to 1000 m in plutonic rock of the Canadian Shield. The solid waste would be isolated from the biosphere by a multibarrier system consisting of engineered barriers, including long-lived containers and clay and cement-based sealing materials, and the natural barrier provided by the massive geological formation. The technical feasibility of this concept and its impact on the environment and human health are being documented in an Environmental Impact Statement (EIS), which will be submitted for review under the federal Environmental Assessment and Review Process. This report, one of nine EIS primary references, describes the various alternative designs and materials for engineered barriers that have been considered during the development of the Canadian disposal concept and summarizes engineered barrier concepts being evaluated in other countries. The basis for the selection of a reference engineered barrier system for the EIS is presented. This reference system involves placing used CANDU (Canada Deuterium Uranium) fuel bundles in titanium containers, which would then be emplaced in boreholes drilled in the floor of disposal rooms. Clay-based sealing materials would be used to fill both the space between the containers and the rock and the remaining excavations. In the section on waste forms, the properties of both used-fuel bundles and solidified high-level wastes, which would be produced by treating wastes resulting from the reprocessing of used fuel, are discussed. Methods of solidifying the wastes and the chemical durability of the solidified waste under disposal conditions are reviewed. Various alternative container designs are reviewed, ranging from preliminary conceptual designs to designs that have received extensive prototype testing. Results of structural performance, welding and inspection studies are also summarized. The corrosion of

  9. Clays in natural and engineered barriers for radioactive waste confinement

    International Nuclear Information System (INIS)

    2007-01-01

    The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO 2 geological sequestration, chemical waste isolation

  10. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO{sub 2} geological sequestration, chemical waste isolation

  11. Barriers and paths to market for genetically engineered crops.

    Science.gov (United States)

    Rommens, Caius M

    2010-02-01

    Each year, billions of dollars are invested in efforts to improve crops through genetic engineering (GE). These activities have resulted in a surge of publications and patents on technologies and genes: a momentum in basic research that, unfortunately, is not sustained throughout the subsequent phases of product development. After more than two decades of intensive research, the market for transgenic crops is still dominated by applications of just a handful of methods and genes. This discrepancy between research and development reflects difficulties in understanding and overcoming seven main barriers-to-entry: (1) trait efficacy in the field, (2) critical product concepts, (3) freedom-to-operate, (4) industry support, (5) identity preservation and stewardship, (6) regulatory approval and (7) retail and consumer acceptance. In this review, I describe the various roadblocks to market for transgenic crops and also discuss methods and approaches on how to overcome these, especially in the United States.

  12. Barriers to the clinical translation of orthopedic tissue engineering.

    Science.gov (United States)

    Evans, Christopher H

    2011-12-01

    Tissue engineering and regenerative medicine have been the subject of increasingly intensive research for over 20 years, and there is concern in some quarters over the lack of clinically useful products despite the large sums of money invested. This review provides one perspective on orthopedic applications from a biologist working in academia. It is suggested that the delay in clinical application is not atypical of new, biologically based technologies. Some barriers to progress are acknowledged and discussed, but it is also noted that preclinical studies have identified several promising types of cells, scaffolds, and morphogenetic signals, which, although not optimal, are worth advancing toward human trials to establish a bridgehead in the clinic. Although this transitional technology will be replaced by more sophisticated, subsequent systems, it will perform valuable pioneering functions and facilitate the clinical development of the field. Some strategies for achieving this are suggested. © Mary Ann Liebert, Inc.

  13. PEBS. Long-term performance of engineered barrier systems

    Energy Technology Data Exchange (ETDEWEB)

    Wieczorek, Klaus; Czaikowski, Oliver; Miehe, Ruediger

    2014-12-15

    The evolution of the engineered barrier system (EBS) of geological repositories for radioactive waste has been the subject of many national and international research programmes. The emphasis of the research activities was on the elaboration of a detailed understanding of the complex THMC processes, which are expected to evolve in the early post closure period in the near field. From the perspective of radiological long-term safety, an in-depth understanding of these coupled processes is of great significance, because the evolution of the EBS during the early post-closure phase may have a non-negligible impact on the radiological safety functions at the time when the canisters breach. Unexpected process interactions during the resaturation phase could impair the safety-relevant parameters in the EBS (e. g. swelling pressure, hydraulic conductivity, diffusivity).

  14. Engineered barrier durability: An issue for disposal near populated areas

    International Nuclear Information System (INIS)

    Porter, C.L.

    1995-01-01

    Under the current national policy for disposal of low-level radioactive waste (LLW) in the United States of America, each State is required to provide disposal capacity for the LLW generated within its borders. The formation of ''Compacts'' of several States is allowed if approved by Congress. Such forced regionalization of disposal facilities based on State boundaries results in some disposal facilities being sited near populated areas at locations with less than optimum site characteristics from a disposal standpoint. To compensate for this engineered barriers are included in the proposed designs. Portland cement based concrete (PCC), which is the dominant material for disposal vault designs, is degraded via many mechanisms, most of which are related to its permeability. The numerous uncertainties associated with the long-term performance of PCC has lead to many unsuccessful attempts to obtain public acceptance of proposed disposal facilities. These unsuccessful efforts have delayed establishing disposal capacity to the point that a crisis is looming on the horizon. This paper investigates the results of on-going research into the viability of commercially available, impermeable, mass-poured construction materials as an alternative to PCC in LLW disposal vaults. The results from testing and research on two such materials, concrete made from sulfur polymer cement (SPC) and ICOM (an epoxy based concrete) are reported. Material properties and test results include strength parameters, chemical resistance, porosity, permeability, deconability, radiation damage resistance, and biodegradation. The data indicates that with these alternative materials the uncertainties in predicting service life of an engineered barrier can be reduced

  15. Development of the Canadian used fuel repository engineered barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Hatton, C., E-mail: chatton@nwmo.ca [Nuclear Waste Management Organization, Toronto, ON (Canada)

    2015-07-01

    The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of Adaptive Phased Management (APM), the federally-approved plan for the safe long-term management of Canada's used nuclear fuel. Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable rock formation. In implementing APM, the NWMO is committed to ensure consistency with international best practices in the development of its repository system, including any advances in technology. In 2012, the NWMO undertook an optimization study to look at both the design and manufacture of its engineered barriers. This study looked at current technologies for the design and manufacture of used fuel containers, placement technologies, repository design, and buffer and sealing systems, while taking into consideration the state of the art worldwide in repository design and acceptance. The result of that study is the current Canadian engineered barrier system, consisting of a 2.7 tonne used fuel container with a carbon-steel core, copper-coated surface and welded spherical heads. The used fuel container is encapsulated in a bentonite buffer box at the surface and then transferred underground. Once underground, the used fuel is placed into a repository room which is cut into the rock using traditional drill-and-blast technologies. This paper explains the logic for the selection of the container and sealing system design and the development of innovative technologies for their manufacture including the use of laser welding, cold spray and pulsed-electrodeposition copper coating for the manufacture of the used fuel container, isostatic presses for the production of the one-piece bentonite blocks, and slip-skid technologies for placement into the repository. (author)

  16. Development of the Canadian used fuel repository engineered barrier system

    International Nuclear Information System (INIS)

    Hatton, C.

    2015-01-01

    The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of Adaptive Phased Management (APM), the federally-approved plan for the safe long-term management of Canada's used nuclear fuel. Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable rock formation. In implementing APM, the NWMO is committed to ensure consistency with international best practices in the development of its repository system, including any advances in technology. In 2012, the NWMO undertook an optimization study to look at both the design and manufacture of its engineered barriers. This study looked at current technologies for the design and manufacture of used fuel containers, placement technologies, repository design, and buffer and sealing systems, while taking into consideration the state of the art worldwide in repository design and acceptance. The result of that study is the current Canadian engineered barrier system, consisting of a 2.7 tonne used fuel container with a carbon-steel core, copper-coated surface and welded spherical heads. The used fuel container is encapsulated in a bentonite buffer box at the surface and then transferred underground. Once underground, the used fuel is placed into a repository room which is cut into the rock using traditional drill-and-blast technologies. This paper explains the logic for the selection of the container and sealing system design and the development of innovative technologies for their manufacture including the use of laser welding, cold spray and pulsed-electrodeposition copper coating for the manufacture of the used fuel container, isostatic presses for the production of the one-piece bentonite blocks, and slip-skid technologies for placement into the repository. (author)

  17. Engineered sorbent barriers for low-level waste disposal

    International Nuclear Information System (INIS)

    Mitchell, S.J.; Freeman, H.D.; Buelt, J.L.

    1986-01-01

    Pacific Northwest Laboratory is developing sorbent materials to prevent the migration of radionuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Screening studies identified promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent, adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt %), activated charcoal (6 wt %), synthetic zeolite (20 wt %), and soil (73 wt %) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 2 refs., 6 figs., 3 tabs

  18. Evaluation of engineered barriers at the Idaho National Engineering and Environmental Laboratory

    International Nuclear Information System (INIS)

    Bhatt, R.N.; Porro, I.

    1998-03-01

    Subsurface Disposal (SDA) of the Radioactive Waste Management Complex serves as the low level waste burial ground at the Idaho National Engineering and Environmental Laboratory (INEEL). The low level wastes are buried in trenches, pits, and soil vaults in surficial sediments. A closure/post-closure plan must be written prior to closure of the SDA. The closure plan for the facility must include a design for an engineered barrier closure cover that will meet all applicable regulatory requirements. This paper describes the approach being followed at the INEEL to choose an appropriate cover design for the SDA closure. Regulatory requirements and performance objectives potentially applicable to closure of the SDA were identified. Technical issues related to SDA closure were identified from a literature search of previous arid site engineered barrier studies and from previous SDA closure cover evaluations. Five engineered barrier conceptual design alternatives were identified: (1) a bio/capillary barrier cover, (2) a thin soil cover, (3) a thick soil cover, (4) a Resource Conservation and Recovery Act cover, and (5) a concrete sealed surface cover. Two of these designs were chosen for in situ hydraulic testing, rather than all five, in order to maximize the amount of information generated relative to projected project costs. Testing of these two cover designs provides data to quantify hydrologic model input parameters and for verification of site specific hydrologic models for long term closure cover performance evaluation and detailed analysis of closure cover alternatives. The specific objectives of the field tests are to determine the water balance for the two covers over several years and to determine cover soil physical and hydraulic properties

  19. Preparation and Characterization of Phenolic Resin/Montmorillonite Nanocomposite

    Directory of Open Access Journals (Sweden)

    Morteza Soltan-Dehghan

    2012-12-01

    Full Text Available Phenolic resins have been widely used for selective high technology applications due to their excellent ablative properties, structural integrity and thermal stability that make them appropriate for thermal insulation materials, wood products industry, coatings, moulding compounds and composite materials. Polymer layered silicate nanocomposites based on montmorillonite (MMT have attracted a great deal of attention because of enhanced properties in mechanical, thermal, barrier and clarity properties without a significant increase in density, which is not possible with conventional fillers. Phenolic resin/montmorillonite (Cloisite 15A nanocomposite was prepared by a combined route of solution blending and in-situ polymerization. Theoptimized conditions for preparation of nanocomposite were achieved by evaluation of various processing parameters (mechanical mixer, high speed disperser and high energy ultrasonic source, mixing time (0.5, 1, 3, 10, 24, 48, 72, and 96 h and different amounts of montmorillonite (5 and 10 weight percents of montmorillonite relative to resol. X-Ray Diffractometer and thermal gravimetric analyzer were used accordingly to show the degree of nanodispersions of organomontmorillonite in polymeric matrix and the effect of nanofiller on thermal stability of nanocomposite with respect to neatresol. The results of high energy ultrasonic source show that a nanocomposite of phenolic resin with 5 wt% montmorillonite displays the best dispersion of clay layers. Thermal stability of nanocomposite was increased by 27% in comparison with neat resol.

  20. Engineered Barrier System performance requirements systems study report. Revision 02

    Energy Technology Data Exchange (ETDEWEB)

    Balady, M.A.

    1997-01-14

    This study evaluates the current design concept for the Engineered Barrier System (EBS), in concert with the current understanding of the geologic setting to assess whether enhancements to the required performance of the EBS are necessary. The performance assessment calculations are performed by coupling the EBS with the geologic setting based on the models (some of which were updated for this study) and assumptions used for the 1995 Total System Performance Assessment (TSPA). The need for enhancements is determined by comparing the performance assessment results against the EBS related performance requirements. Subsystem quantitative performance requirements related to the EBS include the requirement to allow no more than 1% of the waste packages (WPs) to fail before 1,000 years after permanent closure of the repository, as well as a requirement to control the release rate of radionuclides from the EBS. The EBS performance enhancements considered included additional engineered components as well as evaluating additional performance available from existing design features but for which no performance credit is currently being taken.

  1. Engineered Barrier System performance requirements systems study report. Revision 02

    International Nuclear Information System (INIS)

    Balady, M.A.

    1997-01-01

    This study evaluates the current design concept for the Engineered Barrier System (EBS), in concert with the current understanding of the geologic setting to assess whether enhancements to the required performance of the EBS are necessary. The performance assessment calculations are performed by coupling the EBS with the geologic setting based on the models (some of which were updated for this study) and assumptions used for the 1995 Total System Performance Assessment (TSPA). The need for enhancements is determined by comparing the performance assessment results against the EBS related performance requirements. Subsystem quantitative performance requirements related to the EBS include the requirement to allow no more than 1% of the waste packages (WPs) to fail before 1,000 years after permanent closure of the repository, as well as a requirement to control the release rate of radionuclides from the EBS. The EBS performance enhancements considered included additional engineered components as well as evaluating additional performance available from existing design features but for which no performance credit is currently being taken

  2. Biogeochemical and engineered barriers for preventing spread of contaminants.

    Science.gov (United States)

    Baltrėnaitė, Edita; Lietuvninkas, Arvydas; Baltrėnas, Pranas

    2018-02-01

    The intensive industrial development and urbanization, as well as the negligible return of hazardous components to the deeper layers of the Earth, increases the contamination load on the noosphere (i.e., the new status of the biosphere, the development of which is mainly controlled by the conscious activity of a human being). The need for reducing the spread and mobility of contaminants is growing. The insights into the role of the tree in the reduction of contaminant mobility through its life cycle are presented to show an important function performed by the living matter and its products in reducing contamination. For maintaining the sustainable development, natural materials are often used as the media in the environmental protection technologies. However, due to increasing contamination intensity, the capacity of natural materials is not sufficiently high. Therefore, the popularity of engineered materials, such as biochar which is the thermochemically modified lignocellulosic product, is growing. The new approaches, based on using the contaminant footprint, as well as natural (biogeochemical) and engineered barriers for reducing contaminant migration and their application, are described in the paper.

  3. Simulation of the long term alteration of clay minerals in engineered bentonite barriers: nucleation and growth of secondary clay particles

    International Nuclear Information System (INIS)

    Fritz, B.; Clement, A.; Zwingmann, H.; Noguera, C.

    2010-01-01

    Document available in extended abstract form only. The long term stability of clay rich rocks used as barriers to the migration of radionuclides in the environment of nuclear wastes has been intensively studied, looking at the geochemical interactions between clay minerals and aqueous solutions. These studies combine experimental approaches for the short term and numerical modellings for the long term extrapolations, in the frame of the research supported by ANDRA in the French design for High Level Waste (HLW) repository. The main objective of the geochemical numerical tools devoted to clay-solutions interaction processes was to predict the feed-back effects of mineralogical and chemical transformations of clay mineral, in repository conditions as defined by Andra, on their physical and transport properties (porosity, molecular diffusion, permeability). The 1D transport-reaction coupled simulation was done using the code KIRMAT, at 100 deg. C for 100000 years. The fluid considered is that of the Callovo-Oxfordian geological formation (COX) and assumed to diffuse into the clay barrier from one side. On the other side, ferrous iron, is provided by the steel overpack corrosion. Under these conditions, montmorillonite of the clay barrier is only partially transformed into illite, chlorite, and saponite. The simulation shows that only outer parts of the clay barrier is significantly modified, mainly at the interface with the geological environment. These modifications correspond to a closure of the porosity, followed by a decrease of mass transport by molecular diffusion. Near the COX, the swelling pressure of the clays from the barrier is predicted to decrease, but in its major part, the engineered barrier seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure). In this modelling approach, the very important role of secondary clay minerals has to be taken into account with relevant kinetic rate laws; particularly

  4. Preliminary engineering specifications for a test demonstration multilayer protective barrier cover system

    International Nuclear Information System (INIS)

    Phillips, S.J.; Gilbert, T.W.; Adams, M.R.

    1985-03-01

    This report presents preliminary engineering specifications for a test protective barrier cover system and support radiohydrology facility to be constructed at the Hanford Protective Barrier Test Facility (PBTF). Construction of this test barrier and related radiohydrology facility is part of a continuing effort to provide construction experience and performance evaluation of alternative barrier designs used for long-term isolation of disposed radioactive waste materials. Design specifications given in this report are tentative, based on interim engineering and computer simulation design efforts. Final definitive design specifications and engineering prints will be produced in FY 1986. 6 refs., 10 figs., 1 tab

  5. Reducing barriers to energy efficiency in the German mechanical engineering sector. Executive summary

    Energy Technology Data Exchange (ETDEWEB)

    Schleich, J.; Boede, U.

    2000-12-01

    This report describes the empirical research into barriers to energy efficiency in the German mechanical engineering (ME) sector. It is one of nine such reports in the BARRIERS project. The report contains description and analysis of four case studies of energy management in German companies in the ME sector. The results are analysed using the theoretical framework developed for the BARRIERS project. The report also provides brief recommendations on how these barriers to the rational use of energy (RUE) may be overcome and how energy efficiency within the ME sector may be improved. The results of the study for the ME sector in Germany are summarised in this executive summary under the following headings: - Characterising the mechanical engineering sector; - Case studies of energy management in the German mechanical engineering sector; - Evidence of barriers in the German mechanical engineering sector; - The role of energy service companies in the mechanical engineering sector; - Policy implications. (orig.)

  6. Reducing barriers to energy efficiency in the German mechanical engineering sector. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schleich, J.; Boede, U.

    2000-12-01

    This report describes the empirical research into barriers to energy efficiency in the German mechanical engineering (ME) sector. It is one of nine such reports in the BARRIERS project. The report contains description and analysis of four case studies of energy management in German companies in the ME sector. The results are analysed using the theoretical framework developed for the BARRIERS project. The report also provides brief recommendations on how these barriers to the rational use of energy (RUE) may be overcome and how energy efficiency within the ME sector may be improved. The results of the study for the ME sector in Germany are summarised in this executive summary under the following headings: - Characterising the mechanical engineering sector; - Case studies of energy management in the German mechanical engineering sector; - Evidence of barriers in the German mechanical engineering sector; - The role of energy service companies in the mechanical engineering sector; - Policy implications. (orig.)

  7. Natural analog study of engineered protective barriers at the Hanford Site

    International Nuclear Information System (INIS)

    Bjornstad, B.N.; Teel, S.S.

    1993-09-01

    The purpose of this study is to evaluate surficial sedimentary deposits formed in the Pasco Basin over the geologic past as analogs for engineered protective barriers. Evidence for likely changes to be expected in an engineered barrier are preserved in geologically recent deposits. Although the design life of the engineered bonier is only 1,000 years, soils and sediments of this age are uncommon in the Pasco Basin. The evidence of and probability for the following natural processes that could adversely affect the long-term stability of an engineered protective barrier reviewed in this report are deflation by wind, soil compaction, soil eluviation/illuviation, bioturbation, and cryoturbation

  8. Backfill barriers: the use of engineered barriers based on geologic materials to assure isolation of radioactive wastes in a repository

    International Nuclear Information System (INIS)

    Apps, J.A.; Cook, N.G.W.

    1981-06-01

    A preliminary assessment is made to show that canisters fabricated of nickel-iron alloys, and surrounded by a suitable backfill, may produce an engineered barrier where the canister material is thermodynamically stable with respect to its environment. As similar conditions exist in nature, the performance of such systems as barriers to isolate radionuclides can be predicted over very long periods, of the order of 10 6 years

  9. Improved Barriers to Turbine Engine Fragments: Final Annual Report

    National Research Council Canada - National Science Library

    Shockey, Donald

    2002-01-01

    .... Previous large-scale fragment impact testing of comer peg-mounted fabric barriers indicated that the failure of the fabric around the pegged hole was a significant factor in the barrier's effectiveness...

  10. Evaluation of Subsurface Engineered Barriers at Waste Sites

    National Research Council Canada - National Science Library

    1998-01-01

    .... Environmental Protection Agency's (EPA) waste programs with a national retrospective analysis of barrier field performance, and information that may be useful in developing guidance on the use and evaluation of barrier systems...

  11. Engineered Barrier System Thermal-Hydraulic-Chemical Column Test Report

    International Nuclear Information System (INIS)

    W.E. Lowry

    2001-01-01

    The Engineered Barrier System (EBS) Thermal-Hydraulic-Chemical (THC) Column Tests provide data needed for model validation. The EBS Degradation, Flow, and Transport Process Modeling Report (PMR) will be based on supporting models for in-drift THC coupled processes, and the in-drift physical and chemical environment. These models describe the complex chemical interaction of EBS materials, including granular materials, with the thermal and hydrologic conditions that will be present in the repository emplacement drifts. Of particular interest are the coupled processes that result in mineral and salt dissolution/precipitation in the EBS environment. Test data are needed for thermal, hydrologic, and geochemical model validation and to support selection of introduced materials (CRWMS M and O 1999c). These column tests evaluated granular crushed tuff as potential invert ballast or backfill material, under accelerated thermal and hydrologic environments. The objectives of the THC column testing are to: (1) Characterize THC coupled processes that could affect performance of EBS components, particularly the magnitude of permeability reduction (increases or decreases), the nature of minerals produced, and chemical fractionation (i.e., concentrative separation of salts and minerals due to boiling-point elevation). (2) Generate data for validating THC predictive models that will support the EBS Degradation, Flow, and Transport PMR, Rev. 01

  12. Temperature effect on the behaviour of engineered clay barriers

    International Nuclear Information System (INIS)

    Tang, A.M.

    2005-11-01

    The present work deals with the thermo-hydro-mechanical behaviour of compacted swelling clay used for engineered barriers in high-level radioactive repositories. The MX80 bentonite was chosen for this work. Firstly, an experimental work on the thermal conductivity of the compacted bentonite was performed. The results evidenced the effects of dry density, water content, volumetric fraction of soil components, microstructure, and mineralogy. This experimental work gave rise to the proposition of a theoretical model for estimate the thermal conductivity of compacted bentonites. Secondly, after a calibration of suction generated by saturated saline solution in function of temperature, water retention curves were determined at different temperatures. The experimental results showed a decrease of the water retention capacity of soil after heating. A simple model based on the interfacial tension air-water was formulated to simulate this effect. Thirdly, a new isotropic cell enabling a simultaneous control of suction, temperature and mechanical stress was developed. With this new cell, an experimental work on the thermo-mechanical behaviour of the unsaturated compacted bentonite was performed. Finally, a constitutive model was developed for simulate the thermo-hydro-mechanical behaviours obtained experimentally. (author)

  13. Characterization of cement paste as engineered barrier of borehole repository

    International Nuclear Information System (INIS)

    Ferreira, Eduardo G.A.; Isiki, Vera L. K.; Miyamoto, Hissae; Marumo, Julio T.; Vicente, Roberto

    2009-01-01

    Results of axial rupture by compression of cylindrical cement paste samples are presented. This is part of a research on cement paste behavior aiming at investigating the durability of cementitious materials in the environment of repositories for radioactive waste. Portland cement paste is intended to be used as a backfill in a deep borehole for disposal of sealed radiation sources which concept is under development. The service life of the engineered barrier materials plays an important role in the long term safety of such facilities. Accelerated tests in laboratory are being used to evaluate the performance of cement paste under the temperature expected at some hundred meters below grade, under exposure to the radiation emitted by the sources, and under the attack of aggressive chemicals dissolved in the groundwater, during the millennia necessary for the decay of the most active and long-lived radionuclides present in the waste. The large variability in results of mechanical strength as measured by axial compression of cylindrical samples is the subject of this short communication. (author)

  14. Using a systems engineering process to develop engineered barrier system design concepts

    International Nuclear Information System (INIS)

    Jardine, L.J.; Short, D.W.

    1991-05-01

    The methodology used to develop conceptual designs of the engineered barrier system and waste packages for a geologic repository is based on an iterative systems engineering process. The process establishes a set of general mission requirements and then conducts detailed requirements analyses using functional analyses, system concept syntheses, and trade studies identifications to develop preliminary system concept descriptions. The feasible concept descriptions are ranked based on selection factors and criteria and a set of preferred concept descriptions is then selected for further development. For each of the selected concept descriptions, a specific set of requirements, including constraints, is written to provide design guidance for the next and more detailed phase of design. The process documents all relevant waste management system requirements so that the basis and source for the specific design requirements are traceable and clearly established. Successive iterations performed during design development help to insure that workable concepts are generated to satisfy the requirements. 4 refs., 2 figs

  15. H, HM, and THM-C processes in engineered barriers

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Y.J.; Tang, A.M.; Loiseau, C.; Delage, P.; Polak, M.; Souli, H.; Fleureau, J.M.; Wu, P.L.; Tien, Y.M.; Romero, E.; LI, Xiang Ling; Tanaka, Y.; Hasegawa, T.; Nakamura, K.; Sahara, F.; Murakami, T.; Kobayashi, I.; Mihara, M.; Ohi, T.; Lu, J.D.; Huang, W.H.; Lee, W.Y.; Sui, I.H.; Villar, M.V.; Sanchez, M.; Gens, A.; Samper, J.; Lu, C.; Montenegro, L.; Birgersson, M.; Karnland, O.; Nilsson, U.; Akesson, M.; Kristensson, O.; Gatabin, C.; Yang, C.R.; Huang, W.H.; Hsiao, T.H.; Dueck, A.; Lonnqvist, M.; Goudarzi, R.; Borgesson, L.; Fernandez, A.M.; Rivas, P.; Melon, A.M.; Villar, M.V.; Ferrow, E.; Bender Koch, Ch.; Suzuki, S.; Sazarashi, M.; Takegahara, T.; Takao, H.; Tanai, K.; Matsumoto, K.; Gatabin, C.; Touze, G.; Imbert, C.; Guillot, W.; Billaud, P

    2007-07-01

    This session gathers 24 articles (posters) dealing with: determining water permeability of a compacted bentonite sand mixture under confined and free-swell conditions; the model prediction of engineered barrier system effectiveness in the fracture at laboratory scale; the changes in the hydraulic properties of a smectite in presence of chromium; the wall friction and ejection behaviour of bentonite-base buffer material; the thermo-hydro-mechanical behaviour of a large scale mock-up test 'Ophelie' in Belgium: laboratory characterization and numerical modelling; modeling swelling characteristics and permeability of several compacted bentonite affected by saline water; modelling for the long-term Mechanical and Hydraulic behaviour of bentonite-based materials considering chemical transitions; the coupled thermal-hydro analysis on partially saturated bentonite; the behaviour of a bentonite barrier in the laboratory: experimental results up to 8 years and numerical simulation; a coupled hydrogeochemical calculations of the interactions of corrosion products and bentonite; the freezing in saturated bentonite: a thermodynamic approach; the mechanical modeling of MX-80: Development of constitutive laws; the mechanical modeling of MX-80 - Quick tools for BBM parameter analysis; TBT{sub 3} Mock-up test-experimental and model results; the suction characteristics of two compacted bentonite; the retention curves and volume change properties of unsaturated MX-80 bentonite: a laboratory study; humidity induced swelling and water absorption rate of highly compacted bentonite; unconfined compression tests on bentonite samples exposed to high temperature during long time in the field test lot; the thermophysical properties of bentonite; the geochemistry and mineralogy of a bentonite subjected to heating and hydration in an in-situ test after five years operation; the LOT project, long term test of buffer material at Aespoe: a Moessbauer spectroscopic study; the self

  16. Surmounting the Barriers: Ethnic Diversity in Engineering Education: Summary of a Workshop

    Science.gov (United States)

    National Academies Press, 2014

    2014-01-01

    "Surmounting the Barriers: Ethnic Diversity in Engineering Education" is the summary of a workshop held in September 2013 to take a fresh look at the impediments to greater diversification in engineering education. The workshop brought together educators in engineering from two- and four-year colleges and staff members from the three…

  17. The acid-base titration of montmorillonite

    Science.gov (United States)

    Bourg, I. C.; Sposito, G.; Bourg, A. C.

    2003-12-01

    Proton binding to clay minerals plays an important role in the chemical reactivity of soils (e.g., acidification, retention of nutrients or pollutants). If should also affect the performance of clay barriers for waste disposal. The surface acidity of clay minerals is commonly modelled empirically by assuming generic amphoteric surface sites (>SOH) on a flat surface, with fitted site densities and acidity constant. Current advances in experimental methods (notably spectroscopy) are rapidly improving our understanding of the structure and reactivity of the surface of clay minerals (arrangement of the particles, nature of the reactive surface sites, adsorption mechanisms). These developments are motivated by the difficulty of modelling the surface chemistry of mineral surfaces at the macro-scale (e.g., adsorption or titration) without a detailed (molecular-scale) picture of the mechanisms, and should be progressively incorporated into surface complexation models. In this view, we have combined recent estimates of montmorillonite surface properties (surface site density and structure, edge surface area, surface electrostatic potential) with surface site acidities obtained from the titration of alpha-Al2O3 and SiO2, and a novel method of accounting for the unknown initial net proton surface charge of the solid. The model predictions were compared to experimental titrations of SWy-1 montmorillonite and purified MX-80 bentonite in 0.1-0.5 mol/L NaClO4 and 0.005-0.5 mol/L NaNO3 background electrolytes, respectively. Most of the experimental data were appropriately described by the model after we adjusted a single parameter (silanol sites on the surface of montmorillonite were made to be slightly more acidic than those of silica). At low ionic strength and acidic pH the model underestimated the buffering capacity of the montmorillonite, perhaps due to clay swelling or to the interlayer adsorption of dissolved aluminum. The agreement between our model and the experimental

  18. Molecular dynamics simulations of the three-layer hydrate of Na-montmorillonite

    International Nuclear Information System (INIS)

    Holmboe, Michael; Bourg, Ian C.

    2012-01-01

    Document available in extended abstract form only. In many nuclear waste repositories concepts, compacted and smectite-rich bentonite clay is considered as an engineered transport barrier surrounding the canisters holding the nuclear waste. One of the requirements in the safety assessment of these repositories is to predict the transport rate of radionuclides as well as the overall hydraulic conductivity through the bentonite barrier. Kozaki and co-workers have obtained important information from diffusion experiments in bentonite on the mechanisms that control solute transport by studying the temperature-dependence of apparent diffusivity for solutes such as Na + , Cs + and Sr 2+ . Their results showed that the apparent diffusivity follows an Arrhenius relation (ln D a ∝ -E A /RT) with distinct activation energies of diffusion (E A ) for certain montmorillonite compactions, ionic strengths, and types of interlayer cation (Na + vs. Ca 2+ ). Their results suggest that solutes follow different diffusion pathways in compacted montmorillonite at different experimental conditions. In order to identify these transport pathways in compacted montmorillonite one needs independent knowledge of the relative abundance of the different types of interlayer nano-pores, i.e. the different coexisting hydration states (1W-3W), and of the molecular-scale EA for solute diffusion on the external basal surfaces of montmorillonite particles and in the interlayer nano-pores. The latter property can be obtained using molecular dynamics (MD) simulations, an important tool in the characterization of clays and clay minerals that yields detailed atomistic insights into the structural, dynamical and thermodynamic properties of many different geochemically relevant systems. In particular, MD simulations yield insight into the behavior of individual atoms, where most experimental methods only would probe the average behavior of large numbers of atoms or molecules. Thus, by simulating systems of

  19. IPR Barriers in Collaboration between University and Engineering Industry in Sweden

    OpenAIRE

    Huang, Wenting

    2011-01-01

    This thesis examines the barriers, especially intellectual property rights concerned that inhibit industry academia collaboration. By analyzing Swedish firms in the engineering industry, I explore the influence of IPR barrier on firms’ benefits, short- and long-term respectively from university-industry interaction. Three hypotheses are suggested to investigate the relationship between IPR barriers, firm categories, short-term benefits and long-term benefits. The results illustrate different ...

  20. Improved Barriers to Turbine Engine Fragments: Final Annual Report

    National Research Council Canada - National Science Library

    Shockey, Donald

    2002-01-01

    This final annual technical report describes the progress rnade during year 4 of the SPI International Phase II effort to develop a computational capability for designing lightweight fragment barriers...

  1. Radiation damage study in montmorillonites. Application to the high-level nuclear waste disposal in France

    International Nuclear Information System (INIS)

    Sorieul, St.

    2003-11-01

    Smectite is a major component of bentonite, a material considered for engineered barriers in high level nuclear wastes repositories (HLNWR). In order to predict the long-term performance of the bentonite, various physical and chemical factors such as, e.g., thermal gradient, redox potential or mechanical stresses are currently considered. By contrast, little is known about radiation effects in smectite, although it might affect the properties of this mineral through cumulative radiation damages produced by ionizing radiations. The present study focuses on radiation damage in montmorillonite considered herein as a simplified model of bentonite. Two reference clays have been selected, one from Liaoning (China, CHI), containing native radiation-induced defects, and the other (called MX) separated from the MX80 reference bentonite (Wyoming, USA). They are distinguished by layer composition, particularly iron content (1 % and 4 % for CHI and MX, respectively). Radiation effects have been studied by combining X-ray diffraction, Fourier transform infrared spectroscopy, Electron Paramagnetic Resonance (EPR) and Moessbauer spectroscopies. Ionizing irradiation induces two main effects. First, several paramagnetic point defects are identified as trapped holes located on oxygen atoms of the smectite structure. These defects are characterized by different thermal stabilities, according to annealing experiments. Their creation is limited by saturation curve with maximum damage around 100 MGy. The response of the two montmorillonites is different in terms of nature and production of point defects, indicating a role of layer composition and structural precursors. Besides, EPR and Moessbauer results show substantial modifications of the oxidation state of structural iron, which are sample and dose-dependent. Irradiation induces reduction and oxidation of iron in CHI and MX samples, respectively. Moreover, physico-chemical treatments show that intensity of redox effects varies

  2. Investigations of the Montmorillonite and Aluminium Trihydrate Addition Effects on the Ignitability and Thermal Stability of Asphalt

    Directory of Open Access Journals (Sweden)

    Kai Zhu

    2014-01-01

    Full Text Available By means of limiting oxygen index (LOI, cone calorimeter, and TG-DSC tests, this paper investigated the effect of unmodified montmorillonite (MMT, organically modified montmorillonite (OMMT, and aluminium trihydrate (ATH additions on the flame retardancy for asphalt combustion. Experimental results showed that adding a small amount of montmorillonite did not significantly increase the oxygen index of the asphalt but reduced the heat release rate during asphalt combustion. TGA tests had indicated that the montmorillonite (MMT and OMMT could suppress the release of flammable volatiles and form more asphaltenes, which hence postponed the burnout time of asphalt. Furthermore, the combination of montmorillonite (MMT and OMMT and ATH had yielded a synergistic effect, which had further reduced the heat release rate and also increased the oxygen index of asphalt. In particular, after further addition of OMMT, the barrier layer showed less crack, leading to a significant decrease in the heat release rate as compared to the adding of ATH alone.

  3. Improved Barriers to Turbine Engine Fragments: Interim Report II

    National Research Council Canada - National Science Library

    Shockey, Donald

    1999-01-01

    Because fragments from in-flight engine failures can damage critical aircraft components and produce catastrophic consequences, the Federal Aviation Administration is sponsoring research to mitigate...

  4. CHARACTERIZATION OF BENTONITE FOR ENGINEERED BARRIER SYSTEMS IN RADIOACTIVE WASTE DISPOSAL SITES

    Directory of Open Access Journals (Sweden)

    Dubravko Domitrović

    2012-07-01

    Full Text Available Engineered barrier systems are used in radioactive waste disposal sites in order to provide better protection of humans and the environment from the potential hazards associated with the radioactive waste disposal. The engineered barrier systems usually contain cement or clay (bentonite because of their isolation properties and long term performance. Quality control tests of clays are the same for all engineering barrier systems. Differences may arise in the required criteria to be met due for different application. Prescribed clay properties depend also on the type of host rocks. This article presents radioactive waste management based on best international practice. Standard quality control procedures for bentonite used as a sealing barrier in radioactive waste disposal sites are described as some personal experiences and results of the index tests (free swelling index, water adsorption capacity, plasticity limits and hydraulic permeability of bentonite (the paper is published in Croatian.

  5. Engineered surface barriers for waste disposal sites: lysimeter facility design and construction

    International Nuclear Information System (INIS)

    Phillips, S.J.; Ruben, M.S.; Kirkham, R.R.

    1988-01-01

    A facility to evaluate performance of engineered surface carriers for confinement of buried wastes has been designed, constructed, and operations initiated. The Field Lysimeter Test Facility is located at the US Department of Energy's Hanford Site in Richland, Washington. The facility consists of 18 one-dimensional drainage and weighing lysimeters used to evaluate 7 replicated barrier treatments. Distinct layers of natural earth materials were used to construct layered soil and rock barriers in each lysimeter. These barrier designs are capable in principal of significantly reducing or precluding infiltration of meteoric water through barriers into underlying contaminated zones. This paper summarizes salient facility design and construction features used in testing of the Hanford Site's engineered surface barriers

  6. Self-healing thermal barrier coatings; with application to gas turbine engines

    NARCIS (Netherlands)

    Ponnusami, S.A.

    2013-01-01

    Thermal Barrier Coating (TBC) systems have been applied in turbine engines for aerospace and power plants since the beginning of the 1980s to increase the energy efficiency of the engine, by allowing for higher operation temperatures. TBC systems on average need to be replaced about four times

  7. Engineered passive bioreactive barriers: risk-managing the legacy of industrial soil and groundwater pollution.

    Science.gov (United States)

    Kalin, Robert M

    2004-06-01

    Permeable reactive barriers are a technology that is one decade old, with most full-scale applications based on abiotic mechanisms. Though there is extensive literature on engineered bioreactors, natural biodegradation potential, and in situ remediation, it is only recently that engineered passive bioreactive barrier technology is being considered at the commercial scale to manage contaminated soil and groundwater risks. Recent full-scale studies are providing the scientific confidence in our understanding of coupled microbial (and genetic), hydrogeologic, and geochemical processes in this approach and have highlighted the need to further integrate engineering and science tools.

  8. Industrial characterization and validation of clay materials like engineering barrier

    International Nuclear Information System (INIS)

    Rivas, P.; Villar, M.V.; Martin, P.L.; Perez del Villar, L.; Cruz, B. de la; Cozar, J.S.; Dardaine, M.; Lajudie, A.

    1993-01-01

    This report analyzes the bentonites in Madrid and Almeria in order to select the material to built the barrier between the containers and granitic LOCK. The main objective was focussed to test radioactive waste storage in granitic LOCK. The institutions involved in this project are, CIEMAT (Spain), CEA (France), UAM (Spain) and CSIC (Spain)

  9. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Marty, N

    2006-11-15

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  10. Natural analogue study on engineered barriers for underground disposal of radioactive wastes

    International Nuclear Information System (INIS)

    Araki, K.; Motegi, M.; Emoto, Y.; Kaji, Y.; Ikari, S.; Nada, T.; Watanabe, T.

    1989-01-01

    This is a report to develop the natural analogue methodology for the assessment of the life of the engineered barriers beyond the time period of normal experiments, 1000 years, for the disposal of low-level radioactive wastes with activity levels greater than those of wastes acceptable for shallow land burial in Japan. Geological and archeological events and objects available for the assessment of the possible life of each engineered barrier are surveyed. Taking heavy precipitation into account in Japan, a long-term, zero-release engineered barrier system using long-term durable materials based on the natural analogue events and objects is proposed along with the conventional type of water permeable engineered barrier system. The combination of the material quality and the environment that could be achieved within the repository is important for the long-term durability of the engineered barrier material. It is proposed that for the natural analogue study a physico-chemical methodology, which may be referred to as the physico-chemical natural history, is necessary to get parameters from the natural analogue events for the long-term assessment of the disposal system

  11. Progress in waste package and engineered barrier system performance assessment and design

    International Nuclear Information System (INIS)

    Van Luik, A.; Stahl, D.; Harrison, D.

    1993-01-01

    As part of the U.S. Department of Energy's evaluation of site suitability for a potential high-level radioactive waste repository, long-term interactions between the engineered barrier system and the site must be determined. This requires a waste-package/engineered-system design, a description of the environment around the emplacement zone, and models that simulate operative processes describing these engineered/natural systems interactions. Candidate designs are being evaluated, including a more robust, multi-barrier waste package, and a drift emplacement mode. Tools for evaluating designs, and emplacement mode are the currently available waste-package/engineered-system performance assessment codes development for the project. For assessments that support site suitability, environmental impact, or licensing decisions, more capable codes are needed. Code capability requirements are being written, and existing codes are to be evaluated against those requirements. Recommendations are being made to focus waste-packaging/engineered-system code-development

  12. Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

    Science.gov (United States)

    Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

    2009-01-01

    Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

  13. Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

    International Nuclear Information System (INIS)

    Smith, M.J.

    1980-05-01

    This document represents a compilation of data and interpretive studies conducted as part of the engineered barriers program of the Basalt Waste Isolation Project. The overall objective of these studies is to provide information on barrier system designs, emplacement and isolation techniques, and chemical reactions expected in a nuclear waste repository located in the basalts underlying the Hanford Site within the state of Washington. Backfills, waste-basalt interactions, sorption, borehole plugging, etc., are among the topics discussed

  14. Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.J.

    1980-05-01

    This document represents a compilation of data and interpretive studies conducted as part of the engineered barriers program of the Basalt Waste Isolation Project. The overall objective of these studies is to provide information on barrier system designs, emplacement and isolation techniques, and chemical reactions expected in a nuclear waste repository located in the basalts underlying the Hanford Site within the state of Washington. Backfills, waste-basalt interactions, sorption, borehole plugging, etc., are among the topics discussed.

  15. Influences of engineered barrier systems on low-level radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, L. P.

    1987-09-15

    There are major differences between the current practices of shallow land burial and alternative concepts for the disposal of low-level radioactive wastes. Additional protection provided with engineered barrier systems can overcome major concerns the public has with shallow land burial: subsidence; percolating ground waters; radionuclide migration; and the vulnerability of shallow trenches to intrusion. The presence of a variety of engineered barriers to restrict water movement, retain radionuclides and to prevent plant animal or human intrusion leads to significant changes to input data for performance assessment models. Several programs which are underway to more accurately predict the long-term performance of engineered barriers for low-level waste will be described.

  16. Influences of engineered barrier systems on low-level radioactive waste disposal

    International Nuclear Information System (INIS)

    Buckley, L.P.

    1987-09-01

    There are major differences between the current practices of shallow land burial and alternative concepts for the disposal of low-level radioactive wastes. Additional protection provided with engineered barrier systems can overcome major concerns the public has with shallow land burial: subsidence; percolating ground waters; radionuclide migration; and the vulnerability of shallow trenches to intrusion. The presence of a variety of engineered barriers to restrict water movement, retain radionuclides and to prevent plant animal or human intrusion leads to significant changes to input data for performance assessment models. Several programs which are underway to more accurately predict the long-term performance of engineered barriers for low-level waste will be described

  17. Functions of an engineered barrier system for a nuclear waste repository in basalt

    International Nuclear Information System (INIS)

    Coons, W.E.; Moore, E.L.; Smith, M.J.; Kaser, J.D.

    1980-01-01

    Defined in this document are the functions of components selected for an engineered barrier system for a nuclear waste repository in basalt. The definitions provide a focal point for barrier material research and development by delineating the purpose and operative lifetime of each component of the engineered system. A five-component system (comprised of waste form, canister, buffer, overpack, and tailored backfill) is discussed in terms of effective operation throughout the course of repository history, recognizing that the emplacement environment changes with time. While components of the system are mutually supporting, redundancy is provided by subsystems of physical and chemical barriers which act in concert with the geology to provide a formidable barrier to transport of hazardous materials to the biosphere. The operating philosophy of the conceptual engineered barrier system is clarified by examples pertinent to storage in basalt, and a technical approach to barrier design and material selection is proposed. A method for system validation and qualification is also included which considers performance criteria proposed by external agencies in conjunction with site-specific models and risk assessment to define acceptable levels of system performance

  18. Sustainable Hydraulic Barrier Design Technologies for Effective Infrastructure Engineering

    Directory of Open Access Journals (Sweden)

    Chitral Wijeyesekera Devapriya

    2017-01-01

    Full Text Available Migration of liquids lead to embarrassing post construction scenarios such as that of leaks from roofs, potable water leaking from water tanks/ reservoirs, rising damp in walls with groundwater seeping into basement structures, leakage of water from ornamental lakes and ponds or leachate leakage into the environment from MSW landfill sites. Such failures demand immediate and expensive maintenance. A stringent control on structural and waterproof stability is deemed necessary for long term service life of structures and in particular underground and near surface structures. On a micro scale and over a longer time scale, the phenomenon of rising dampness occurs in older buildings with the groundwater rising up through walls, floors and masonry via capillary action. Even slower rates of contaminant fluid migration occur through landfill base liners. In this paper a variety of hydraulic barrier technologies is critically discussed against a backdrop of relevant case studies. The choice of an appropriate hydraulic barrier technology for a given scenario will depend also on the sustainability, financial affordability and subjective aesthetics.

  19. Thermal analysis of the effect of thick thermal barrier coatings on diesel engine performance

    International Nuclear Information System (INIS)

    Hoag, K.L.; Frisch, S.R.; Yonushonis, T.M.

    1986-01-01

    The reduction of heat rejection from the diesel engine combustion chamber has been the subject of a great deal of focus in recent years. In the pursuit of this goal, Cummins Engine Company has received a contract from the Department of Energy for the development of thick thermal barrier coatings for combustion chamber surfaces. This contract involves the analysis of the impact of coatings on diesel engine performance, bench test evaluation of various coating designs, and single cylinder engine tests. The efforts reported in this paper center on the analysis of the effects of coatings on engine performance and heat rejection. For this analysis the conventional water cooled engine was compared with an engine having limited oil cooling, and utilizing zirocnia coated cylinder had firedecks and piston crowns. The analysis showed little or no benefits of similarly coating the valves or cylinder liner

  20. Engineered barrier systems (EBS) in the context of the entire safety case

    International Nuclear Information System (INIS)

    2003-01-01

    A joint NEA-EC workshop entitled 'Engineered Barrier Systems (EBS) in the Context of the Entire Safety Case' was organised in Oxford on 25-27 September 2002 and hosted by United Kingdom Nirex Limited. The main objectives of the workshop were to provide a status report on engineered barrier systems in various national radioactive waste management programmes considering deep geological disposal; to establish the value to member countries of a project on EBS; and to define such a project's scope, timetable and modus operandi. This report presents the outcomes of this workshop. (author)

  1. Engineered Barrier Systems (EBS) in the Context of the Entire Safety Case

    International Nuclear Information System (INIS)

    2005-01-01

    A joint NEA-EC workshop entitled ''Engineered Barrier Systems (EBS) in the Context of the Entire Safety Case'' was organised in Oxford on 25-27 September 2002 and hosted by United Kingdom Nirex Limited. The main objectives of the workshop were to provide a status report on engineered barrier systems in various national radioactive waste management programmes considering deep geological disposal; to establish the value to member countries of a project on EBS; and to define such a project scope, timetable and modus operandi. This report presents the outcomes of this workshop. (author)

  2. The swelling behavior of montmorillonite as affected by the grain size by in situ X-ray diffraction experiments

    International Nuclear Information System (INIS)

    Morodome, S.; Kawamura, K.; Owada, H.; Yahagi, R.; Kobayashi, I.

    2012-01-01

    Document available in extended abstract form only. In many existing researches, the swelling behavior and impermeability of smectitic engineered barrier materials in disposal facilities of radioactive waste was investigated. In the RWMC-project, the effect of smectite content on the mechanical and hydraulic behavior of smectitic materials is investigated and modeled to introduce into THMC analysis. However, since smectite is a natural resource, physical and chemical properties are different with places of production. In order to model the swelling behavior and impermeability of smectitic materials, not only the smectite content but also layer charge and crystal size will be the primary factors. In addition, smectite types and impurity minerals contents or soluble salts affect bentonite characteristic, as well. In this research, in order to focus on the effect of grain size of smectite, the swelling behavior of smectitic materials which are the same place of production but are different grain size were investigated. The smectitic material used in this study was Kunipia-F (Kunimine Industry Co. Ltd., Japan), which is from the Tukinuno Mine, Yamagata prefecture, Japan, and is purified montmorillonite produced by hydraulic elutriation. It is considered that the montmorillonite, Kunipia-F, has large crystal size, and for example Kunipia-F is able to make a sheet when drying weak solution. The grain size was conditioned by jet mill pulverizer. The pulverizing was conducted by making each other collide with high speed. The grain size of the intact and pulverized samples was measured by using of the laser scattering particle distribution analyzer and SEM. The swelling behavior was measured by in situ X-ray diffraction using of a sample chamber which can control the temperature and humidity precisely. The result of the laser scattering analysis denoted that the pulverized sample fined down expressly. The difference of the crystal aspect ratio of the pre- and post

  3. Electrical and dielectric investigation of intercalated polypyrrole montmorillonite nanocomposite prepared by spontaneous polymerization of pyrrole into Fe(III)-montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Zidi, Rabii, E-mail: rabiizidi@gmail.com [Physical Chemistry Laboratory for Mineral Materials and their Applications, National Center for Research in Materials Sciences (CNRSM), B.P.73, 8020 Soliman (Tunisia); Bekri-Abbes, Imene; Sdiri, Nasr [Physical Chemistry Laboratory for Mineral Materials and their Applications, National Center for Research in Materials Sciences (CNRSM), B.P.73, 8020 Soliman (Tunisia); Vimalanandan, Ashokanand; Rohwerder, Michael [Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Srasra, Ezzeddine [Physical Chemistry Laboratory for Mineral Materials and their Applications, National Center for Research in Materials Sciences (CNRSM), B.P.73, 8020 Soliman (Tunisia)

    2016-10-15

    Highlights: • We have prepared and characterized a Fe-MMT/PPy nanocomposites. • Investigate electrical conductivity and dielectric properties of the nanocomposite. • Investigate the temperature and frequency dependencies of alternating current conductivity of nanocomposites. - Abstract: Pyrrole was introduced into Fe(III)-exchanged montmorillonite to spontaneously polymerize within the interlayer resulting in the formation of intercalated polypyrrole-montmorillonite nanocomposite. The molar proportion of pyrrole to interlayer Fe{sup 3+} (R) has been varied from 0.5 to 5. The nanocomposite has been characterized by X-ray diffraction, Scanning Electronic Microscope, FTIR spectroscopy and impedance spectroscopy. It has been shown that intercalated polypyrrole montmorillonite nanocomposite was obtained. The results showed that the dc conductivity and dielectric properties of polypyrrole depend on R. The alternating current (ac) conductivity of the polymer obeys the power law, i.e., σ{sub ac}(ω) = Aω{sup s}. The alternating conductivity of nanocomposite was controlled by the correlated barrier hopping model. The activation energy for alternating current mechanism decreases with increasing frequency which confirms the hopping conduction to the dominant mechanism as compared with the dc activation energy. The dielectric relaxation mechanism was explained on the basis of complex dielectric modulus.

  4. Value engineering study for seletion of verticle barrier technology at a Superfund site

    International Nuclear Information System (INIS)

    Bryan, E.E.; Guglielmetti, J.L.; Butler, P.B.; Brill, M.P.

    1997-01-01

    A value engineering (VE) study was conducted to identify and evaluate vertical barrier technologies and alignments for a Superfund project in New Castle County, Delaware. The objective was to select and recommend the most appropriate vertical barrier(s) for two separate landfills and a portion of the manufacturing plant on the site. A VE team was assembled to identify and evaluate site specific issues related to effectiveness, constructability and cost for numerous vertical barrier technologies. Several cost-effective alternatives were identified that met project objectives. The VE study concluded that a composite vertical barrier system consisting of a soil-bentonite slurry trench and steel sheet piles would provide effective containment of the North Landfill. Additionally, the geologic confining unit specified in the Record of Decision (ROD) was found to be unsuitable as a vertical barrier key and a more suitable, shallow confining unit was discovered. This paper describes the value engineering process and results of the VE study for one of the landfills

  5. Durability of Dukovany shallow land repository engineered barriers. Appendix 7: Czech Republic

    International Nuclear Information System (INIS)

    Vokal, A.; Nachmilner, L.; Wasserbauer, R.; Dohnalek, J.

    2001-01-01

    The main aim of this project was to explore the durability of engineering barriers used at Dukovany shallow land repository as a support of safety assessments. This appendix summarises the principal results focused on durability of asphaltopropyleneconcrete (APC) hydroisolation and steel reinforced concrete construction

  6. Employees' Perceptions of Barriers to Participation in Training and Development in Small Engineering Businesses

    Science.gov (United States)

    Susomrith, Pattanee; Coetzer, Alan

    2015-01-01

    Purpose: This paper aims to investigate barriers to employee participation in voluntary formal training and development opportunities from the perspective of employees in small engineering businesses. Design/methodology/approach: An exploratory qualitative methodology involving data collection via site visits and in-depth semi-structured…

  7. Loadings in thermal barrier coatings of jet engine turbine blades an experimental research and numerical modeling

    CERN Document Server

    Sadowski, Tomasz

    2016-01-01

    This book discusses complex loadings of turbine blades and protective layer Thermal Barrier Coating (TBC), under real working airplane jet conditions. They obey both multi-axial mechanical loading and sudden temperature variation during starting and landing of the airplanes. In particular, two types of blades are analyzed: stationary and rotating, which are widely applied in turbine engines produced by airplane factories.

  8. Engineered clay-shredded tyre mixtures as barrier materials

    International Nuclear Information System (INIS)

    Al-Tabbaa, A.; Aravinthan, T.

    1997-01-01

    An engineered clay consisting of kaolin and bentonite was mixed with shredded tyre in various weight percentages and examined for use as a constituent in a landfill liner. The clay-tyre mixtures properties in terms of compaction, unconfined compressive strength, permeability to water and paraffin, leachability, stress-strain behaviour, free swell behaviour and swelling pressure were investigated. The results show that the dry density and strength reduced with the addition of tyre and also with increased tyre content but that good interaction was developed between the clay and tyre. The strain at failure increased showing reinforcing effect of the tyre. The permeability to paraffin was considerably reduced compared to that to water due to the presence of the tyre which caused high swelling pressures to develop. The leachability results indicate initial high concentrations leaching out of the soil-tyre mixtures which will be subjected to dilution in the environment. This work adds evidence to the potential advantages of using soil-tyre mixtures as a landfill liner material

  9. Investigation of metallic, ceramic, and polymeric materials for engineered barrier applications in nuclear-waste packages

    International Nuclear Information System (INIS)

    Westerman, R.E.

    1980-10-01

    An effort to develop licensable engineered barrier systems for the long-term (about 1000 yr) containment of nuclear wastes under conditions of deep continental geologic disposal has been underway at Pacific Northwest Laboratory since January 1979, under the auspices of the High-Level Waste Immobilization Program. In the present work, the barrier system comprises the hard or structural elements of the package: the canister, the overpack(s), and the hole sleeve. A number of candidate metallic, ceramic, and polymeric materials were put through mechanical, corrosion, and leaching screening tests to determine their potential usefulness in barrier-system applications. Materials demonstrating adequate properties in the screening tests will be subjected to more detailed property tests, and, eventually, cost/benefit analyses, to determine their ultimate applicability to barrier-system design concepts. The following materials were investigated: two titanium alloys of Grade 2 and Grade 12; 300 and 400 series stainless steels, Inconels, Hastelloy C-276, titanium, Zircoloy, copper-nickel alloys and cast irons; total of 14 ceramic materials, including two grades of alumina, plus graphite and basalt; and polymers such as polyamide-imide, polyarylene, polyimide, polyolefin, polyphenylene sulfide, polysulfone, fluoropolymer, epoxy, furan, silicone, and ethylene-propylene terpolymer (EPDM) rubber. The most promising candidates for further study and potential use in engineered barrier systems were found to be rubber, filled polyphenylene sulfide, fluoropolymer, and furan derivatives

  10. Nanocomposites prepared from acrylonitrile butadiene rubber and organically modified montmorillonite with vinyl groups

    Science.gov (United States)

    Han, Mijeong; Kim, Hoonjung; Kim, Eunkyoung

    2006-01-01

    Nanocomposites were prepared from acrylonitrile-butadiene rubber (NBR), vinyl groups containing organically modified montmorillonite and additives, such as zinc oxide, stearic acid, and sulfur. The organically modified montmorillonites used in these nanocomposites were prepared by ion exchange reactions of N,N'-dimethylalkyl-(p-vinylbenzyl)-ammonium chlorides (DAVBAs, alkyl = octyl, dodecyl, and octadecyl) with sodium montmorillonite (Na+-MMT). NBR nanocomposites were obtained by controlling both the mixing and vulcanization conditions, by using a Brabender mixer and hot-press process. X-ray diffraction (XRD) analysis shows that, depending on the amount of montmorillonite that is added, both exfoliated and intercalated nanocomposite structures are formed. The NBR/DAVBA-MMT nanocomposites exhibit much higher mechanical properties (e.g., tensile strength, Young's modulus, 300% modulus, and hardness) as well as gas barrier properties as compared to NBR Na+-MMT or NBR composites generated from modified montmorillonites without vinyl groups. Consistent with the results of XRD, transmission electron microscopy (TEM) reveals that the intercalation and exfoliation structures of the nanocomposites coexist and that the DAVBA-MMT layers are well dispersed in NBR.

  11. Study on the saturating and swelling behavior of an engineering bentonite barrier using a test model

    International Nuclear Information System (INIS)

    Nakajima, Makoto; Kobayashi, Ichizo; Toida, Masaru; Fujisaki, Katsutoshi

    2007-01-01

    The conceptual design of a disposal facility with additional buffer depth for radioactive waste is mainly constituted from the multi-barrier system that is constructed around the waste form so that it prevents radionuclide transfer to the biosphere. The engineered bentonite barrier is one of the elements of the multi-barrier system and is constructed with homogeneous bentonite-containing material compacted to a high density so that there are no voids. Due to the swelling characteristics of the bentonite material, the self-sealing function which is an important function of the bentonite barrier can work, but at the same time it mechanically affects the neighboring structures. Therefore, an experimental study was implemented in order to evaluate the mechanical effect of the bentonite swelling behavior throughout the construction, emplacement operations and closure re-saturation phase. In this article, the results of swelling tests to obtain the mechanical properties of the bentonite and three types of test model experiments performed for the event observations in the different saturation processes are described. As a result, the effects of a seepage pattern of ground water and a variation in the density produced by construction on the swelling pressure distribution of the bentonite barrier could be reproduced and validated. It is thought that they will be important events when ground water permeates the bentonite layer of a multiple barrier system. (author)

  12. PILOT-SCALE EVALUATION OF ENGINEERED BARRIER SYSTEMS FOR THE YUCCA MOUNTAIN PROJECT

    International Nuclear Information System (INIS)

    Webb, S.W.; George, J.T.; Finley, R.E.

    2001-01-01

    This paper describes two quarter-scale experiments (1.4 m diameter) and associated numerical analyses on granular backfill engineered barrier systems in support of the Yucca Mountain Project for the potential repository. The two configurations include a sloped capillary barrier and a plain backfill. The tests involve application of dyed water as a constant line infiltration source along the top of the test set-up, monitoring water movement through the test, and measuring water exiting the experiments. A complete water balance estimate is made for each test, and observed water movement is compared with (1) detailed numerical analyses conducted using the TOUGH2 code for unsaturated flow in porous media and (2) posttest observations. The results of the testing and analyses show that for the injection rates and configuration applied, the capillary barrier design diverts a significant amount of all injected water and the TOUGH2 pretest predictions show qualitative and quantitative agreement with the experimental data

  13. First polarization-engineered compressively strained AlInGaN barrier enhancement-mode MISHFET

    International Nuclear Information System (INIS)

    Hahn, Herwig; Reuters, Ben; Wille, Ada; Ketteniss, Nico; Kalisch, Holger; Vescan, Andrei; Benkhelifa, Fouad; Ambacher, Oliver

    2012-01-01

    One current focus of research is the realization of GaN-based enhancement-mode devices. A novel approach for the realization of enhancement-mode behaviour is the utilization of polarization matching between the barrier and the GaN buffer. Yet, the utilization of a quaternary barrier combining polarization engineering together with a large conduction band offset has not been demonstrated so far. Here, epitaxially grown, compressively strained AlInGaN is applied as a nearly polarization-matched barrier layer on GaN resulting in enhancement-mode operation. The insulated-gate devices are fabricated gate-first with Al 2 O 3 as gate dielectric. Passivated metal insulator semiconductor heterostructure field effect transistors yielded threshold voltages (V th ) of up to +1 V. The devices withstand negative and positive gate-biased stress and a positive V th is maintained even after long-time negative bias stress. (paper)

  14. Investigation of the long term stability and corrosion resistance of engineering barriers

    International Nuclear Information System (INIS)

    Aoyama, Eri; Tachikawa, Hirokazu; Shimizu, Akihiko

    2005-03-01

    The Japan Nuclear Cycle Development Institute submitted 'Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan' to the Japanese government. This report contains investigations of the long term behavior of alteration of bentonite, and of the corrosion life time of overpack on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However some subjects, such as the behavior of the bentonite and overpack under high pH conditions and the behavior of the engineering barrier with change of near-field environmental condition with time for promoting reliability have still been left. To take into account these conditions, expert committees composed of clay science and metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment were investigated from the view points of long term stability and corrosion resistance of engineering barrier. (author)

  15. Construction and operational experiences of engineered barrier test facility for near surface disposal of LILW

    International Nuclear Information System (INIS)

    Park, Jin Beak; Park, Se Moon; Kim, Chang Lak

    2003-01-01

    Engineered barrier test facility is specially designed to demonstrate the performance of engineered barrier system for the near-surface disposal facility under the domestic environmental conditions. Comprehensive measurement systems are installed within each test cell. Long-and short-term monitoring of the multi-layered cover system can be implemented according to different rainfall scenarios with artificial rainfall system. Monitoring data on the water content, temperature, matric potential, lateral drainage and percolation of cover-layer system can be systematically managed by automatic data acquisition system. The periodic measurement data are collected and will be analyzed by a dedicated database management system, and provide a basis for performance verification of the disposal cover design

  16. Nonmetallic engineered barriers, their properties and role in a geologic repository for high level radioactive waste

    International Nuclear Information System (INIS)

    Lisy, F.

    1994-01-01

    The efficiency of engineered barrier systems depends to a great extent on the properties of the materials used. Backfill and sealing materials must fulfill certain requirements and criteria. They must feature low hydraulic conductivity, high retardation capacity, extremely good sorption properties for a wide range of radionuclides potentially leachable from the deposited waste, low permeability, good compatibility with engineered and natural barriers, good workability, and availability in the necessary quantity and at a reasonable price. Some basic properties are presented of materials which fulfill, to a considerable degree, these requirements and which are thus suggested as suitable backfills, sealings of buffers, namely clay- and cement-based materials (concretes, mortars, etc.). A brief information is also given on some other materials like bitumen, asphalt, etc. (Z.S.) 4 refs

  17. Assessment of Environmental Factors of Geology on Waste and Engineering Barriers for Waste Storage Near Surface

    International Nuclear Information System (INIS)

    Arimuladi SP

    2007-01-01

    Geological environment factors include features and processes occurring within that spatial and temporal (post-closure) domain whose principal effect is to determine the evolution of the physical, chemical, biological and human conditions of the domain that are relevant to estimating the release and migration of radionuclide and consequent exposure to man. Hardness of radioactive waste and engineer barrier can be decrease by environmental factors. Disposal system domain geological environment factors is a category in the International FEP list and is divided into sub-categories. There are 13 sub-factors of geological environment, 12 sub-factors influence hardness of radioactive waste and engineer barrier, thermal processes and conditions in geosphere can be excluded. (author)

  18. Nanocomposite biofilms obtained from Whitemouth croaker (Micropogonias furnieri) protein isolate and Montmorillonite: evaluation of the physical, mechanical and barrier properties; Biofilmes nanocompositos obtidos de isolado proteico de corvina (Micropogonias furnieri) e Montmorilonita: avaliacao das propriedades fisicas, meanicas e de barreira

    Energy Technology Data Exchange (ETDEWEB)

    Cortez-Vega, William Renzo, E-mail: williamvega@ufgd.edu.br [Universidade Federal da Grande Dourados (UFGD), MS (Brazil). Fac. de Engenharia; Bagatini, Daniela Cardozo; Souza, Juliana Tais Andreghetto de; Prentice, Carlos, E-mail: danielabagatini@hotmail.com, E-mail: ju.andreghetto@hotmail.com, E-mail: dqmprent@furg.b [Universidade Federal do Rio Grande (FURG), RS (Brazil). Escola de Quimica e Alimentos

    2013-06-15

    The objective of this study was to evaluate the properties of nanocomposite biofilms based on Whitemouth croaker (Micropogonias furnieri) protein isolate with organophilic clays. Initially the croaker protein isolate (CPI) was obtained using the pH shifting process from by-products of croaker industrialization. A Box and Behnken experimental design was used to develop the films, with three levels of CPI (2, 3.5 and 5 g.100 g{sup -1} solution), montmorillonite MMT clay (0.3, 0.5 and 0.7 g.100 g{sup -1} solution) and glycerol (25, 30 and 35 g.100g{sup -1} CPI). The polymeric films were produced by the 'casting technique'. The tensile strength values ranged from 7.2 to 10.7 MPa and the elongation values from 39.6 to 45.8 %. The water vapor permeability (WVP) values ranged from 3.2 to 5.5 (g.mm.m{sup -2}.d{sup -1}) and the CPI had an average protein content of 97.87 % protein (d. b.). It was concluded that the nanocomposite films produced from CPI with MMT were promising from the standpoint of their mechanical properties, visual appearance and easy handling, as well as for their low water vapor permeability and low water solubility. With respect to their mechanical properties, the concentrations of CPI and MMT were the main factors influencing the development of the nanocomposite films. The results obtained from the experimental design indicated that 3.5 g of CPI.100 g{sup -1}solution, 0.5 g of MMT.100 g{sup -1} solution and 30 g of glycerol.100 g{sup -1} CPI would be the ideal parameters for the development of nanocomposite films by 'casting'. (author)

  19. Nanocomposite biofilms obtained from Whitemouth croaker (Micropogonias furnieri) protein isolate and Montmorillonite: evaluation of the physical, mechanical and barrier properties; Biofilmes nanocompositos obtidos de isolado proteico de corvina (Micropogonias furnieri) e Montmorilonita: avaliacao das propriedades fisicas, meanicas e de barreira

    Energy Technology Data Exchange (ETDEWEB)

    Cortez-Vega, William Renzo, E-mail: williamvega@ufgd.edu.br [Universidade Federal da Grande Dourados (UFGD), MS (Brazil). Fac. de Engenharia; Bagatini, Daniela Cardozo; Souza, Juliana Tais Andreghetto de; Prentice, Carlos [Universidade Federal do Rio Grande (FURG), RS (Brazil). Escola de Quimica e Alimentos

    2013-06-15

    The objective of this study was to evaluate the properties of nanocomposite biofilms based on Whitemouth croaker (Micropogonias furnieri) protein isolate with organophilic clays. Initially the croaker protein isolate (CPI) was obtained using the pH shifting process from by-products of croaker industrialization. A Box and Behnken experimental design was used to develop the films, with three levels of CPI (2, 3.5 and 5 g.100 g{sup -1} solution), montmorillonite MMT clay (0.3, 0.5 and 0.7 g.100 g{sup -1} solution) and glycerol (25, 30 and 35 g.100g{sup -1} CPI). The polymeric films were produced by the 'casting technique'. The tensile strength values ranged from 7.2 to 10.7 MPa and the elongation values from 39.6 to 45.8 %. The water vapor permeability (WVP) values ranged from 3.2 to 5.5 (g.mm.m{sup -2}.d{sup -1}) and the CPI had an average protein content of 97.87 % protein (d. b.). It was concluded that the nanocomposite films produced from CPI with MMT were promising from the standpoint of their mechanical properties, visual appearance and easy handling, as well as for their low water vapor permeability and low water solubility. With respect to their mechanical properties, the concentrations of CPI and MMT were the main factors influencing the development of the nanocomposite films. The results obtained from the experimental design indicated that 3.5 g of CPI.100 g{sup -1}solution, 0.5 g of MMT.100 g{sup -1} solution and 30 g of glycerol.100 g{sup -1} CPI would be the ideal parameters for the development of nanocomposite films by 'casting'. (author)

  20. Engineered barrier system and waste package design concepts for a potential geologic repository at Yucca Mountain

    International Nuclear Information System (INIS)

    Short, D.W.; Ruffner, D.J.; Jardine, L.J.

    1991-10-01

    We are using an iterative process to develop preliminary concept descriptions for the Engineered Barrier System and waste-package components for the potential geologic repository at Yucca Mountain. The process allows multiple design concepts to be developed subject to major constraints, requirements, and assumptions. Involved in the highly interactive and interdependent steps of the process are technical specialists in engineering, metallic and nonmetallic materials, chemistry, geomechanics, hydrology, and geochemistry. We have developed preliminary design concepts that satisfy both technical and nontechnical (e.g., programmatic or policy) requirements

  1. Barriers to the Uptake of Concurrent Engineering in the Nigerian Construction Industry

    Directory of Open Access Journals (Sweden)

    Nathaniel Anny Aniekwu

    2012-12-01

    engineering and also to compute the Kendall’s coefficient of concordance, which assess the levels of agreement among the judges on the consistency of the rankings. A Kendall’s coefficient of concordance of W=0.57365 was recorded. A lack of awareness emerged as the most important barrier against the integration of this concept into the Nigerian construction industry. The top five variables are all human factors that can be ameliorated by proper education.

  2. Choice of french clays as engineered barrier components for waste disposal

    International Nuclear Information System (INIS)

    Coulon, H.; Lajudie, A.; Debrabant, P.; Atabek, R.; Jorda, M.; Andre-Jehan, R.

    1987-01-01

    Results are presented of physical measurements on candidate buffer materials for use in nuclear fuel waste disposal. The materials being considered as constituent elements of engineered barriers are essentially calcium smectite clays, in other terms swelling clays, coming from fourteen french deposits. The criteria for good candidates are mainly: smectite content in the clay materials, carbonate and organic material content and bulk density of the material, compacted under a pressure of 100 MPa. 14 references, 4 figures, 6 tables

  3. Bentonite engineered barrier building method for radioactive waste on sub-surface disposal test project

    International Nuclear Information System (INIS)

    Mori, Takuo; Takahashi, Shinichi; Takeuchi, Kunifumi; Namiki, Kazuto

    2008-01-01

    The engineering barriers such as clay and concrete materials are planned to use for covering radioactive waste in cavern-type disposal facility. The requirement to clay barrier is very low permeability, which could be satisfied by high density Bentonite, and such a compaction method will be needed. Two methods, compaction and air shot, were tested in engineering scale for constructing a high-density clay barrier. Two types of compaction equipments, 'Teasel plate' and 'Plate compacter', were developed and engineering scale experiments were performed for compacting Bentonite only and Bentonite-sand-aggregate mixture. As a result, the Teasel plate can reach higher density Bentonite in relatively short time in comparison to other equipments. While, regarding air shot method, an air-shot machine in a tunnel construction site was tested by different water adding methods (wet, dry, and half wet). It is concluded that the dry and half wet constructing methods will achieve reasonable workability. As a result, the best construction option can be chosen according to the locations of radioactive waste facility. (author)

  4. Assessment on mechanical effect of engineering barrier system to fault movement. Research document

    International Nuclear Information System (INIS)

    Hirai, Takashi; Tanai, Kenji; Takaji, Kazuhiko; Ohnuma, Satoshi

    2003-03-01

    The objective of this report is to clarify mechanical effect of engineering barrier system to the unavoidable fault movement. From the basic policy of the second progress report by JNC, natural phenomenon which affect strongly to the geological disposal system should be avoided. However, small faults as sliprate ''C'' far from principal fault zone, are difficult to be found out completely. Therefore, it is important to evaluate the influence of these fault movements and to clarify stability and safety of the engineered barrier system. Accordingly, the effect of a rock displacement across a deposition holl was considered and the midium scale test was carried out. Then midium scale test was simulated by Finit Element Method in which the constitutive model of Tresca was adopted to analyze elastoplastic behavior of buffer material. From the result of the midium scale test and the analysis, it was realized that the buffer material diminish shear stress acting on the overpack. Further analytical study was conducted to evaluate the real scale engineered barrier system designed in the second progress report by JNC. From the study, it was appeared that stress in buffer corresponded to the stress calculated for the midium scale test model. Consequently, it was obvious that rock displacement, 80% of buffer didn't affect overpack if velocity of fault movement was under 10 cm/sec. (author)

  5. Backfill barriers: the use of engineered barriers based on geologic materials to assure isolation of radioactive wastes in a repository. [Nickel-iron alloys

    Energy Technology Data Exchange (ETDEWEB)

    Apps, J.A.; Cook, N.G.W.

    1981-06-01

    A preliminary assessment is made to show that canisters fabricated of nickel-iron alloys, and surrounded by a suitable backfill, may produce an engineered barrier where the canister material is thermodynamically stable with respect to its environment. As similar conditions exist in nature, the performance of such systems as barriers to isolate radionuclides can be predicted over very long periods, of the order of 10/sup 6/ years.

  6. Engineered barrier construction in salt rock. Final report of project phase 2. Period covered: 1 July 1989 - 31 December 1992

    International Nuclear Information System (INIS)

    Stockmann, N.; Beinlich, A.; Droste, J.; Flach, D.; Glaess, F.; Jockwer, N.; Krogmann, P.; Miehe, R.; Moeller, J.; Schwaegermann, F.; Wallmueller, R.; Walter, F.; Yaramanci, U.

    1994-01-01

    The project report presents and explains data obtained by a specific measuring programme, giving evidence of the sealing efficiency of an engineered barrier comprising abutment, long-term barrier, and hydraulic short-term barrier, the sealing performance having been verified for shorter and longer periods of time ( up to approx. 500 years). Specific computer codes have been applied for computing and verifying the long-term efficiency of the complex engineered barrier system (artificial structures and surrounding rock). The technical feasibility and the performance of an engineered barrier for reliable sealing of a radwaste repository is thus demonstrated at a scale of 1:1 at the site of the Asse mine [de

  7. FAILURE MECHANISMS OF THERMAL BARRIER COATINGS INTERNAL COMBUSTION ENGINES AND llMPROVEMENTS

    Directory of Open Access Journals (Sweden)

    ADNAN PARLAK

    2003-04-01

    Full Text Available MechanicaJ properties of high performance ceramics have been improved to the point where their use in heat engines is possible. The high temperature strength and low thermal expansion properties of bigh performance ceramics offer an advantage over metals in the development of non-water cooling engine. However, because bard environment in diesel engine combustion chamber, solving the problem of durabiUty of TBC is important. DurabiUty of thermal barrier coatings(TBC is liınited by two main failure mechanisms: Therınal expansion nlİsmatch betwcen bond coat and top coat and bond coat oxidation. Both of these can cause failure of the ceramic top coat. Developments of recent years sholv that bond coats \\Vith higher oxidation resistance tend to have better coating system cyclic lives

  8. Studies on an advanced repository system with enhanced engineered barriers (a framework)

    International Nuclear Information System (INIS)

    Fujiwara, A.; Tashiro, S.; Ikari, S.; Suzuki, A.

    1993-01-01

    In order to propose advanced designs of repositories with enhanced engineered barriers of relatively high radioactive wastes such as burnable poisons, channel boxes, control rods and highly irradiated metals, studies started in 1987 and completed the first phase in 1992. This paper presents the framework and brief results of the first phase. The studies set preliminary design concepts of the repositories with various combinations with engineered barriers and natural barriers for different models and locations such as a silo type in shallow land or a tunnel type in intermediate depth. Through the designs, four component technics were picked up and studied for (1) construction of the components in repository; (2) performance evaluation to realize repository design; (3) improvement of circumstances inside or around repository; and (4) surveillance of repository performance to realize the repository designs. Finally, some repository systems were provided using obtained results, and then the applicability and the economy were evaluated. The studies will continue to the second phase focusing on the long-term performance of the repositories

  9. Monitoring long-term evolution of engineered barrier systems using magnets: Magnetic response.

    Science.gov (United States)

    Rigonat, N; Isnard, O; Harley, S L; Butler, I B

    2018-01-05

    Remote and non-destructive monitoring of the stability and performance of Engineered Barrier Systems for Geological Disposal Facility of is gaining considerable importance in establishing the safety cases for Higher Activity Wastes disposal. This study offers an innovative use of mineral magnetism for monitoring groundwater saturation of the barrier. Four mixtures of permanent magnets (Nd-Fe-B, coated and uncoated; SmCo and AlNiCo) and bentonite were reacted for 4, 8 and 12 months with mildly-saline, high-pH leachates, representing the fluids saturating a time-evolved engineered barrier. Coupled hysteresis and thermomagnetic analyses demonstrate how Nd-Fe-B feature a time-dependent transition from square-like ferromagnetic to superparamagnetic loop via pot-bellied and wasp-waist loops, whereas SmCo and AlNiCo do not show so extensive corrosion-related variations of the intrinsic and extrinsic magnetic properties. This study allowed to identify magnetic materials suitable for shorter- (Nd-Fe-B) and longer-term (SmCo and AlNiCo) monitoring purposes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Temperature effect on the behaviour of engineered clay barriers; Effet de la temperature sur le comportement des barrieres de confinement

    Energy Technology Data Exchange (ETDEWEB)

    Tang, A.M

    2005-11-15

    The present work deals with the thermo-hydro-mechanical behaviour of compacted swelling clay used for engineered barriers in high-level radioactive repositories. The MX80 bentonite was chosen for this work. Firstly, an experimental work on the thermal conductivity of the compacted bentonite was performed. The results evidenced the effects of dry density, water content, volumetric fraction of soil components, microstructure, and mineralogy. This experimental work gave rise to the proposition of a theoretical model for estimate the thermal conductivity of compacted bentonites. Secondly, after a calibration of suction generated by saturated saline solution in function of temperature, water retention curves were determined at different temperatures. The experimental results showed a decrease of the water retention capacity of soil after heating. A simple model based on the interfacial tension air-water was formulated to simulate this effect. Thirdly, a new isotropic cell enabling a simultaneous control of suction, temperature and mechanical stress was developed. With this new cell, an experimental work on the thermo-mechanical behaviour of the unsaturated compacted bentonite was performed. Finally, a constitutive model was developed for simulate the thermo-hydro-mechanical behaviours obtained experimentally. (author)

  11. Investigating the Potential Barrier Function of Nanostructured Materials Formed in Engineered Barrier Systems (EBS) Designed for Nuclear Waste Isolation.

    Science.gov (United States)

    Cuevas, Jaime; Ruiz, Ana Isabel; Fernández, Raúl

    2018-02-21

    Clay and cement are known nano-colloids originating from natural processes or traditional materials technology. Currently, they are used together as part of the engineered barrier system (EBS) to isolate high-level nuclear waste (HLW) metallic containers in deep geological repositories (DGR). The EBS should prevent radionuclide (RN) migration into the biosphere until the canisters fail, which is not expected for approximately 10 3  years. The interactions of cementitious materials with bentonite swelling clay have been the scope of our research team at the Autonomous University of Madrid (UAM) with participation in several European Union (EU) projects from 1998 up to now. Here, we describe the mineral and chemical nature and microstructure of the alteration rim generated by the contact between concrete and bentonite. Its ability to buffer the surrounding chemical environment may have potential for further protection against RN migration. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Application of engineered sorbent barriers Summary of Laboratory Data for FY 1988

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, H.D.; Jones, E.O.

    1989-09-01

    Laboratory studies were conducted in FY 1988 Pacific Northwest Laboratory to determine the effect of contact time, pH, solution to solid ratio, and particle size on the performance of a number of materials in adsorbing radioactive cobalt, strontium, and cesium. The laboratory studies were conducted to provide background information useful in designing an engineered sorbent barrier, which restricts the migration of radionuclides from low-level waste sites. Understanding how the variables affect the adsorption of ions on the sorbent materials is the key to estimating the performance of sorbent barriers under a variety of conditions. The scope of the studies was limited to three radionuclides and four sorbent materials, but the general approach can be used to evaluate other radionuclides and conditions. The sorbent materials evaluated in this study included clinoptilolite, activated carbon, bentonite clay, and Savannah River soil. The clinoptilolite and activated carbon were identified in previous studies as the most cost-effective materials for sorption of the three radionuclides under consideration. The bentonite clay was evaluated as a component of the barrier that could be used to modify the permeability of the barrier system. The Savannah River soil was used to represent soil from a humid site. 3 refs., 14 figs., 1 tab.

  13. Deep disposal of high activity radioactive wastes: the study of engineered and geological barriers behaviour

    International Nuclear Information System (INIS)

    Yu Jun; Cui; Delage, P.; Laure, E. de; Behrouz, Gatmiri; Sulem, J.; Anh Minh, Tang

    2008-09-01

    One option for the isolation of high activity and long lived radioactive wastes is the disposal of the vitrified waste containers in galleries dug inside impermeable rocks of the deep underground (granite, argillite, salt). The multi-barrier isolation concept is based on the use of successive barriers to avoid the migration of radionuclides towards the biosphere (container envelope, engineered barrier made of compacted swelling clay, and host rock). In parallel to the works carried out in underground laboratories, experiments and simulation works are performed in order to understand the behaviour of storage facilities and barriers under the effects of constraints, water fluxes and temperature changes. In this context, the UR Navier geotechnical team (CERMES), a joint research unit of Ecole des Ponts ParisTech and LCPC, has been working for more than 15 years on this topic for various contractors. These works are based on original experimental devices allowing to identify the thermo-hydro-mechanical phenomena and thereafter to model them. This dossier presents a summary of these works. (J.S.)

  14. Reviews of the In-situ Demonstration Test of the Engineered Barrier System in Many Countries

    International Nuclear Information System (INIS)

    Lee, Minsoo; Choi, Heui Joo

    2013-01-01

    Many nations considering the deep geologic disposal of HLW are now planning or executing in-situ demonstration experiments on their regional EBS (Engineering barrier system) at their deep underground research facilities. The main purpose of the in-situ EBS test is the experimental confirmation of its performance, and the prediction of its long-term evolution through the modeling of EBS based on the experimental data. Additionally, the engineering feasibility for the construction of an engineering barrier system can also be checked through full scale construction of an in-situ test. KAERI is currently preparing an in-situ test at a large 1/3 scale, called IN-DEBS (In-situ Demonstration of EBS) at KURT (KAERI Underground Research Tunnel) for the generic EBS suggested in A-KRS (Advanced KAERI Reference System), which was developed to treat the HLW from pyroprocessing. As the first step for the design of IN-DEBS, the foreign in-situ demonstrations of EBS were reviewed in this paper. The demonstration projects, which were completed or are still being executed in some countries such as Sweden, France, Finland, Canada, Belgium, Switzerland, Spain, and Japan, were surveyed and summarized. In particular, hardware constitutions such as the heating element or compact bentonite, and the experimental procedures, have focused more on reviews than on experimental results in this survey, since their hardware information is very important for the design of the IN-DEBS

  15. Reviews of the In-situ Demonstration Test of the Engineered Barrier System in Many Countries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Minsoo; Choi, Heui Joo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    Many nations considering the deep geologic disposal of HLW are now planning or executing in-situ demonstration experiments on their regional EBS (Engineering barrier system) at their deep underground research facilities. The main purpose of the in-situ EBS test is the experimental confirmation of its performance, and the prediction of its long-term evolution through the modeling of EBS based on the experimental data. Additionally, the engineering feasibility for the construction of an engineering barrier system can also be checked through full scale construction of an in-situ test. KAERI is currently preparing an in-situ test at a large 1/3 scale, called IN-DEBS (In-situ Demonstration of EBS) at KURT (KAERI Underground Research Tunnel) for the generic EBS suggested in A-KRS (Advanced KAERI Reference System), which was developed to treat the HLW from pyroprocessing. As the first step for the design of IN-DEBS, the foreign in-situ demonstrations of EBS were reviewed in this paper. The demonstration projects, which were completed or are still being executed in some countries such as Sweden, France, Finland, Canada, Belgium, Switzerland, Spain, and Japan, were surveyed and summarized. In particular, hardware constitutions such as the heating element or compact bentonite, and the experimental procedures, have focused more on reviews than on experimental results in this survey, since their hardware information is very important for the design of the IN-DEBS.

  16. Engineering an in vitro air-blood barrier by 3D bioprinting

    Science.gov (United States)

    Horváth, Lenke; Umehara, Yuki; Jud, Corinne; Blank, Fabian; Petri-Fink, Alke; Rothen-Rutishauser, Barbara

    2015-01-01

    Intensive efforts in recent years to develop and commercialize in vitro alternatives in the field of risk assessment have yielded new promising two- and three dimensional (3D) cell culture models. Nevertheless, a realistic 3D in vitro alveolar model is not available yet. Here we report on the biofabrication of the human air-blood tissue barrier analogue composed of an endothelial cell, basement membrane and epithelial cell layer by using a bioprinting technology. In contrary to the manual method, we demonstrate that this technique enables automatized and reproducible creation of thinner and more homogeneous cell layers, which is required for an optimal air-blood tissue barrier. This bioprinting platform will offer an excellent tool to engineer an advanced 3D lung model for high-throughput screening for safety assessment and drug efficacy testing. PMID:25609567

  17. Test Plan to Assess Fire Effects on the Function of an Engineered Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Anderson L.; Berlin, Gregory T.; Cammann, Jerry W.; Leary, Kevin D.; Link, Steven O.

    2008-09-29

    Wildfire is a frequent perturbation in shrub steppe ecosystems, altering the flora, fauna, atmosphere, and soil of these systems. Research on the fire effects has focused mostly on natural ecosystems with essentially no attention on engineered systems like surface barriers. The scope of the project is to use a simulated wildfire to induce changes in an engineered surface barrier and document the effects on barrier performance. The main objective is to quantify the effects of burning and the resulting post-fire conditions on alterations in soil physical properties; hydrologic response, particularly the water balance; geochemical properties; and biological properties. A secondary objective is to use the lessons learned to maximize fire protection in the design of long-term monitoring systems based on electronic sensors. A simulated wildfire will be initiated, controlled and monitored at the 200-BP-1 barrier in collaboration with the Hanford Fire Department during the fall of 2008. The north half of the barrier will be divided into nine 12 x 12 m plots, each of which will be randomly assigned a fuel load of 2 kg m-2 or 4 kg m-2. Each plot will be ignited around the perimeter and flames allowed to carry to the centre. Any remaining unburned vegetation will be manually burned off using a drip torch. Progress of the fire and its effects will be monitored using point measurements of thermal, hydrologic, and biotic variables. Three measures of fire intensity will be used to characterize fire behavior: (1) flame height, (2) the maximum temperature at three vertical profile levels, and (3) total duration of elevated temperature at these levels. Pre-burn plant information, including species diversity, plant height, and canopy diameter will be measured on shrubs from the plots to be burned and from control plots at the McGee ranch. General assessments of shrub survival, recovery, and recruitment will be made after the fire. Near-surface soil samples will be collected pre- and

  18. Test Plan to Assess Fire Effects on the Function of an Engineered Surface Barrier

    International Nuclear Information System (INIS)

    Ward, Anderson L.; Berlin, Gregory T.; Cammann, Jerry W.; Leary, Kevin D.; Link, Steven O.

    2008-01-01

    Wildfire is a frequent perturbation in shrub steppe ecosystems, altering the flora, fauna, atmosphere, and soil of these systems. Research on the fire effects has focused mostly on natural ecosystems with essentially no attention on engineered systems like surface barriers. The scope of the project is to use a simulated wildfire to induce changes in an engineered surface barrier and document the effects on barrier performance. The main objective is to quantify the effects of burning and the resulting post-fire conditions on alterations in soil physical properties; hydrologic response, particularly the water balance; geochemical properties; and biological properties. A secondary objective is to use the lessons learned to maximize fire protection in the design of long-term monitoring systems based on electronic sensors. A simulated wildfire will be initiated, controlled and monitored at the 200-BP-1 barrier in collaboration with the Hanford Fire Department during the fall of 2008. The north half of the barrier will be divided into nine 12 x 12 m plots, each of which will be randomly assigned a fuel load of 2 kg m-2 or 4 kg m-2. Each plot will be ignited around the perimeter and flames allowed to carry to the centre. Any remaining unburned vegetation will be manually burned off using a drip torch. Progress of the fire and its effects will be monitored using point measurements of thermal, hydrologic, and biotic variables. Three measures of fire intensity will be used to characterize fire behavior: (1) flame height, (2) the maximum temperature at three vertical profile levels, and (3) total duration of elevated temperature at these levels. Pre-burn plant information, including species diversity, plant height, and canopy diameter will be measured on shrubs from the plots to be burned and from control plots at the McGee ranch. General assessments of shrub survival, recovery, and recruitment will be made after the fire. Near-surface soil samples will be collected pre- and

  19. Performance of high level waste forms and engineered barriers under repository conditions

    International Nuclear Information System (INIS)

    1991-02-01

    The IAEA initiated in 1977 a co-ordinated research programme on the ''Evaluation of Solidified High-Level Waste Forms'' which was terminated in 1983. As there was a continuing need for international collaboration in research on solidified high-level waste form and spent fuel, the IAEA initiated a new programme in 1984. The new programme, besides including spent fuel and SYNROC, also placed greater emphasis on the effect of the engineered barriers of future repositories on the properties of the waste form. These engineered barriers included containers, overpacks, buffer and backfill materials etc. as components of the ''near-field'' of the repository. The Co-ordinated Research Programme on the Performance of High-Level Waste Forms and Engineered Barriers Under Repository Conditions had the objectives of promoting the exchange of information on the experience gained by different Member States in experimental performance data and technical model evaluation of solidified high level waste forms, components of the waste package and the complete waste management system under conditions relevant to final repository disposal. The programme includes studies on both irradiated spent fuel and glass and ceramic forms as the final solidified waste forms. The following topics were discussed: Leaching of vitrified high-level wastes, modelling of glass behaviour in clay, salt and granite repositories, environmental impacts of radionuclide release, synroc use for high--level waste solidification, leachate-rock interactions, spent fuel disposal in deep geologic repositories and radionuclide release mechanisms from various fuel types, radiolysis and selective leaching correlated with matrix alteration. Refs, figs and tabs

  20. Engineered barrier systems and canister orientation studies for the Yucca Mountain Project, Nevada

    International Nuclear Information System (INIS)

    Wilder, D.G.

    1990-07-01

    Emplacement borehole orientation directly impacts many aspects of the Engineered Barrier System (EBS) and interactions with the near field environment. This paper considers the impacts of orientation on the hydrologic portion of the environment and its interactions with the EBS. The hydrologic environments is considered from a conceptual standpoint, the numerical analyses are left for subsequent work. As reported in this paper, several aspects of the hydrological environment are more favorable for long term performance of vertically oriented rather than horizontally oriented Waste Packages. 19 refs., 15 figs

  1. Waste form performance assessment in the YUCCA Mountain engineered barrier system, American Nuclear Society

    International Nuclear Information System (INIS)

    Morris, E. E.; Fanning, T. H.; Wigeland, R. A.

    2000-01-01

    This work demonstrates a technique for comparing the performance of waste forms in a repository environment when one or more of the waste forms constitute a small part of the total amount of waste planned for the repository. In applying the technique, it is important to identify radionuclides that are highly soluble in the transport fluid since it is only for these that the release is controlled by the dissolution rate of the waste form matrix. The techniques presented here have been applied to an evaluation of the performance of waste forms from the electrometallurgical treatment of spent fuel in the proposed Yucca Mountain Repository Engineered Barrier System (EBS)

  2. Examining E-Learning Barriers as Perceived by Faculty Members of Engineering Colleges in the Jordanian Universities

    Science.gov (United States)

    Al-Alawneh, Muhammad K.

    2014-01-01

    Employing computer's technology that includes e-learning system in the field of Engineering is a vital issue which needs to be discussed. Therefore, this study purposed to examine e-learning barriers as perceived by faculty members of engineering in three major universities in Jordan (Yarmouk University, Jordan University of Science and…

  3. Identifying the Barriers upon Development of Virtual Education in Engineering Majors (Case Study: The University of Isfahan)

    Science.gov (United States)

    Nikoonezhad, Sepideh; Nili, Mohammadreza; Esfahani, Ahmadreza Nasr

    2015-01-01

    The present study aims at investigating barriers upon development of virtual education in engineering majors at the University of Isfahan. The study has applied a mixed method (qualitative and quantitative) and its population consists all of the department members of the technical and engineering majors at the University of Isfahan including 125…

  4. Clays in natural and engineered barriers for radioactive waste confinement - 4. International meeting. Book of abstracts

    International Nuclear Information System (INIS)

    2010-01-01

    The 4. edition of the International Meeting 'Clays in Natural and Engineered Barriers for Radioactive Waste Confinement' took place at the 'Cite Internationale des Congres' of Nantes (France). Approximately 500 participants (from about 20 different countries) attended the meeting. All the abstracts (oral and poster sessions) are included in these proceedings. The purpose of this 4. international conference is to gather specialists in the different disciplines related to clays and clay minerals, with scientists from organisations engaged in radioactive waste disposal, in order to evaluate the progress of the research conducted in that field. Multidisciplinary approaches including geology, mineralogy, geochemistry, rheology, geomechanics of clays are required in order to provide a detailed characterisation of the geological host formations considered for the disposal of radioactive waste and to assess the behaviour of engineered and natural barriers when submitted to various types of perturbations induced by disposal facilities. The major objectives for the experimental programs are constituted by the performance evaluation for the natural barrier as well as the impact of repository-induced disturbances upon the confinement properties of clay-rich geological formations. This is being or will be conducted in underground research laboratories, for interpreting the subsequent scientific results, for modelling the long-term behaviour of radioactive waste repositories and for carrying out safety assessment exercises. This conference covers all the aspects of clay characterisation and behaviour relevant to the confinement of radionuclides in clay, considered at various time scales and locations, from the descriptions of basic phenomenological processes to the global understanding of the performance and safety at repository and geological scales. Most of the topics covered by the programme of the conference are in line with the general objectives

  5. Investigation and technical reviews of the long term stability and corrosion resistance of engineering barriers

    International Nuclear Information System (INIS)

    Tachikawa, Hirokazu

    2004-03-01

    The Japan Nuclear Fuel Cycle Development Institute submitted 'Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan' to the Japanese government. This report contains investigations of the long term behavior of alteration of bentonite, and of the corrosion life time of overpack on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However some subjects, such as the behavior of the bentonite and overpack under high pH conditions and the behavior of the engineering barrier with change of near-field environmental condition with time for promoting reliability have still been left. To take into account these conditions, expert committees composed of clay science and metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment were investigated and technically reviewed from the view points of long term stability and corrosion resistance of engineering buffer materials. (author)

  6. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

    Science.gov (United States)

    Karthikeya Sharma, T

    2015-11-01

    Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

  7. Barriers and strategies for the clinical translation of advanced orthopaedic tissue engineering protocols.

    Science.gov (United States)

    Madry, H; Alini, M; Stoddart, M J; Evans, C; Miclau, T; Steiner, S

    2014-05-06

    Research in orthopaedic tissue engineering has intensified over the last decade and new protocols continue to emerge. The clinical translation of these new applications, however, remains associated with a number of obstacles. This report highlights the major issues that impede the clinical translation of advanced tissue engineering concepts, discusses strategies to overcome these barriers, and examines the need to increase incentives for translational strategies. The statements are based on presentations and discussions held at the AO Foundation-sponsored symposium "Where Science meets Clinics 2013" held at the Congress Center in Davos, Switzerland, in September, 2013. The event organisers convened a diverse group of over one hundred stakeholders involved in clinical translation of orthopaedic tissue engineering, including scientists, clinicians, healthcare industry professionals and regulatory agency representatives. A major point that emerged from the discussions was that there continues to be a critical need for early trans-disciplinary communication and collaboration in the development and execution of research approaches. Equally importantly was the need to address the shortage of sustained funding programs for multidisciplinary teams conducting translational research. Such detailed discussions between experts contribute towards the development of a roadmap to more successfully advance the clinical translation of novel tissue engineering concepts and ultimately improve patient care in orthopaedic and trauma surgery.

  8. Barriers and strategies for the clinical translation of advanced orthopaedic tissue engineering protocols

    Directory of Open Access Journals (Sweden)

    H Madry

    2014-05-01

    Full Text Available Research in orthopaedic tissue engineering has intensified over the last decade and new protocols continue to emerge. The clinical translation of these new applications, however, remains associated with a number of obstacles. This report highlights the major issues that impede the clinical translation of advanced tissue engineering concepts, discusses strategies to overcome these barriers, and examines the need to increase incentives for translational strategies. The statements are based on presentations and discussions held at the AO Foundation-sponsored symposium "Where Science meets Clinics 2013" held at the Congress Center in Davos, Switzerland, in September, 2013. The event organisers convened a diverse group of over one hundred stakeholders involved in clinical translation of orthopaedic tissue engineering, including scientists, clinicians, healthcare industry professionals and regulatory agency representatives. A major point that emerged from the discussions was that there continues to be a critical need for early trans-disciplinary communication and collaboration in the development and execution of research approaches. Equally importantly was the need to address the shortage of sustained funding programs for multidisciplinary teams conducting translational research. Such detailed discussions between experts contribute towards the development of a roadmap to more successfully advance the clinical translation of novel tissue engineering concepts and ultimately improve patient care in orthopaedic and trauma surgery.

  9. Magnetic Materials: Novel Monitors of Long-Term Evolution of Engineered Barrier Systems

    Directory of Open Access Journals (Sweden)

    Simon L. Harley

    2016-12-01

    Full Text Available Most safety cases for the deep geological disposal of radioactive waste are reliant on the swelling of bentonite in the engineered barrier system as it saturates with groundwater. Assurance of safety therefore requires effective monitoring of bentonite saturation. The time- and fluid-dependent corrosion of synthetic magnets embedded in bentonite is demonstrated here to provide a novel and passive means of monitoring saturation. Experiments have been conducted at 70 °C in which neo magnets, AlNiCo magnets, and ferrite magnets have been reacted with saline (NaCl, KCl, CaCl2 solutions and alkaline fluids (NaOH, KOH, Ca(OH2 solutions; pH = 12 in the presence of bentonite. Nd-Fe-B magnets undergo extensive corrosion that results in a dramatic change from ferromagnetic to superparamagnetic behaviour concomitant with bentonite saturation. AlNiCo magnets in saline solutions show corrosion but only limited decreases in their magnetic intensities, and ferrite magnets are essentially unreactive on the experimental timescales, retaining their initial magnetic properties. For all magnets the impact of their corrosion on bentonite swelling is negligible; alteration of bentonite is essentially governed by the applied fluid composition. In principle, synthetic magnet arrays can, with further development, be designed and embedded in bentonite to monitor its fluid saturation without compromising the integrity of the engineered barrier system itself.

  10. Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes.

    Science.gov (United States)

    Lopez-Fernandez, Margarita; Cherkouk, Andrea; Vilchez-Vargas, Ramiro; Jauregui, Ruy; Pieper, Dietmar; Boon, Nico; Sanchez-Castro, Ivan; Merroun, Mohamed L

    2015-11-01

    The long-term disposal of radioactive wastes in a deep geological repository is the accepted international solution for the treatment and management of these special residues. The microbial community of the selected host rocks and engineered barriers for the deep geological repository may affect the performance and the safety of the radioactive waste disposal. In this work, the bacterial population of bentonite formations of Almeria (Spain), selected as a reference material for bentonite-engineered barriers in the disposal of radioactive wastes, was studied. 16S ribosomal RNA (rRNA) gene-based approaches were used to study the bacterial community of the bentonite samples by traditional clone libraries and Illumina sequencing. Using both techniques, the bacterial diversity analysis revealed similar results, with phylotypes belonging to 14 different bacterial phyla: Acidobacteria, Actinobacteria, Armatimonadetes, Bacteroidetes, Chloroflexi, Cyanobacteria, Deinococcus-Thermus, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria, Nitrospirae, Verrucomicrobia and an unknown phylum. The dominant groups of the community were represented by Proteobacteria and Bacteroidetes. A high diversity was found in three of the studied samples. However, two samples were less diverse and dominated by Betaproteobacteria.

  11. Performance Confirmation for the Engineered Barrier System. Report of a Workshop

    International Nuclear Information System (INIS)

    Bennett, David G.

    2004-08-01

    As part of preparations for review of future license applications, the Swedish Nuclear Power Inspectorate (SKI) organised a workshop on the engineered barrier system for the KBS-3 concept, focused on Performance Confirmation (PC). The workshop was held during 12 - 14 May, 2004 at Oskarshamn. The main purpose of the workshop was to identify key issues relating to the demonstration of long-term safety using a system of engineered barriers. The workshop began with introductory presentations on Performance Confirmation, on monitoring, and on long-term experiments in underground research laboratories. Working groups were then convened to discuss these topics and identify questions to put to the Swedish Nuclear Fuel and Waste Management Company (SKB) the following day. On the second day, SKB made several presentations, mainly on long-term experiments conducted at the Aespoe underground research laboratory. These presentations were followed by an informal session during which the questions identified by the working groups on the first day were discussed with SKB and its representatives. This report includes the questions identified by the working groups and a summary of the workshop discussions. Extended abstracts for the introductory presentations are included in an appendix. The conclusions and viewpoints presented in this report are those of one or several workshop participants. They do not necessarily coincide with those of SKI

  12. Execution techniques for high level radioactive waste disposal. 4. Design and manufacturing procedure of engineered barriers

    International Nuclear Information System (INIS)

    Ogata, Nobuhide; Kosaki, Akio; Ueda, Hiroyoshi; Asano, Hidekazu; Takao, Hajime

    1999-01-01

    Ensuring the physical integrity of engineered barriers for an extremely long time period is necessary for geological disposal of high-level radioactive wastes. This report describes the design process and the designed configurations of both overpack and buffer as engineered barriers. Manufacturing procedure, quality control and inspection methods are also summarized. Carbon steel was selected as a structural material of the overpack and the specification of the overpack was determined assuming disposal in the depths of 1000 m below surface of crystalline rock site. The mixture of bentonite and sand (80% sodium bentonite and 20% silica sand by mass) was selected as material for a buffer from mainly its permeability and characteristics of self-sealing of a gap occurred in construction work. Welding method of a lid onto the main body of the overpack, uniting method of a corrosion-resistance layer and the structural component in the case of a composite overpack and manufacturing procedures of both blocks-type and monolithic-type buffers are also investigated. (author)

  13. Assessment and Measurements of Degradation Processes in the Engineering Barriers of LILW Repository

    International Nuclear Information System (INIS)

    Zeleznik, N.; Sajna, A.; Petkovsek, B.

    2013-01-01

    In 2009 the Slovenian national agency for radwaste management (ARAO) adopted the national spatial plan for the low and intermediate level waste (LILW) repository to be located in Krsko municipality near NPP Krsko. The selected option for disposal was based on a silo type structure for the near surface disposal facility that will be situated close to a saturated aquifer. The soil in the region can be described as silt that extends a few hundred meters deep. The silt also contains sections of sand or clay. As the possibility exists that the natural geological barrier system will not be able to contain radionuclide migration it is a pre requisite that the proposed LILW repository must install engineered barriers. Research on different cementation materials are currently underway in order to find sustainable materials for the manufacturing of engineered barriers for the repository (silo, backfilling, concrete containers). The research also includes the assessment of possible site specific degradation processes in order to provide a methodology for the selection of appropriate locally available materials that will minimize the degradation processes. The research methodology was based on studying the characteristics (workability, compressive strength), durability (resistance to penetration of water, freeze/thaw resistance, resistance to groundwater), rheology (heat of hydration, autogenous and concrete shrinkage) and reinforcement corrosion of different concrete compositions. The characterization results were used to develop a numerical model for degradation processes to be found in the current concrete compositions. Although initial results indicated that the current concrete compositions are satisfactory, the research must be extended to the addition of binder materials to improve the characteristics of the manufactures concrete before degradation processes can be studied. (author)

  14. Development of backfill material as an engineered barrier in the waste package system. Interim topical report

    International Nuclear Information System (INIS)

    Wheelwright, E.J.; Hodges, F.N.; Bray, L.A.; Westsik, J.H. Jr.; Lester, D.H.; Nakai, T.L.; Spaeth, M.E.; Stula, R.T.

    1981-09-01

    A backfill barrier, emplaced between the containerized waste and the host rock, can both protect the other engineered barriers and act as a primary barrier to the release of radionuclides from the waste package. Attributes that a backfill should provide in order to carry out its required function have been identified. Primary attributes are those that have a direct effect upon the release and transport of radionuclides from the waste package. Supportive attributes do not directly affect radionuclide release but are necessary to support the primary attributes. The primary attributes, in order of importance, are: minimize (retard or exclude) the migration of ground water between the host rock and the waste canister system; retard the migration of selected chemical species (corrosive species and radionuclides) in the ground water; control the Eh and pH of the ground water within the waste-package environment. The supportive attributes are: self-seal any cracks or discontinuities in the backfill or interfacing host geology; retain performance properties at all repository temperatures; retain peformance properties during and after receiving repository levels of gamma radiation; conduct heat from the canister system to the host geology; retain mechanical properties and provide resistance to applied mechanical forces; retain morphological stability and compatibility with structural barriers and with the host geology for required period of time. Screening and selection of candidate backfill materials has resulted in a preliminary list of materials for testing. Primary emphasis has been placed on sodium and calcium bentonites and zeolites used in conjunction with quartz sand or crushed host rock. Preliminary laboratory studies have concentrated on permeability, sorption, swelling pressure, and compaction properties of candidate backfill materials

  15. Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

    Directory of Open Access Journals (Sweden)

    A. Salam

    2007-07-01

    Full Text Available The ice nucleation characteristics of montmorillonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric temperatures and relative humidities with a continuous flow diffusion chamber. The montmorillonite particles were exposed to pure (100% and diluted ammonia gas (25 ppm at room temperature in a stainless steel chamber. There was no significant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure ammonia gas exposure enhanced the ice nucleating fraction of montmorillonite mineral dust particles 3 to 8 times at 90% relative humidity with respect to water (RHw and 5 to 8 times at 100% RHw for 120 min exposure time compared to unexposed montmorillonite within our experimental conditions. The percentages of active ice nuclei were 2 to 8 times higher at 90% RHw and 2 to 7 times higher at 100% RHw in 25 ppm ammonia exposed montmorillonite compared to unexposed montmorillonite. All montmorillonite particles are more efficient as ice nuclei with increasing relative humidities and decreasing temperatures. The activation temperature of montmorillonite exposed to 100% pure ammonia was 15°C higher than for unexposed montmorillonite particles at 90% RHw. In the 25 ppm ammonia exposed montmorillonite experiments, the activation temperature was 10°C warmer than unexposed montmorillonite at 90% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmorillonite mineral dust particles suggesting that the ammonia is chemically bound to the montmorillonite particle. This is the first experimental evidence that ammonia gas exposed montmorillonite mineral dust particles can enhance its activation as ice nuclei and that the activation can occur at temperatures warmer than –10°C where natural atmospheric ice nuclei are very scarce.

  16. Adsorption of ferrous ions onto montmorillonites

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Dawei, E-mail: qdw109@163.com [Qilu University of Technology, Jinan, 250353, Shandong (China); Niu, Xia [Qilu University of Technology, Jinan, 250353, Shandong (China); Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao [Shandong SiBang pharmaceutical co., LTD, Jinan, Shandong, 250200 (China)

    2015-04-01

    Highlights: • Adsorption study of ferrous ions on montmorillonites. • Using ascorbic acid as antioxidants in adsorption process. • Fe (II)-MMT had good affinity for phosphate. - Abstract: The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe{sup 2+}/Fe{sub total} ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG{sup 0} and ΔH{sup 0} were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  17. A new luminescent montmorillonite/borane nanocomposite

    Czech Academy of Sciences Publication Activity Database

    Kolská, Z.; Matoušek, J.; Čapková, P.; Braborec, Jakub; Benkocká, M.; Černá, H.; Londesborough, Michael Geoffrey Stephen

    2015-01-01

    Roč. 118, DEC (2015), s. 295-300 ISSN 0169-1317 Institutional support: RVO:61388980 Keywords : Luminophore * Montmorillonite/borane nanocomposite * X-ray photoelectron spectroscopy * X-ray diffraction * UV–Vis spectra Subject RIV: CA - Inorganic Chemistry Impact factor: 2.586, year: 2015

  18. The Effects of Fire on the Function of the 200-BP-1 Engineered Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Anderson L.; Link, Steven O.; Hasan, Nazmul; Draper, Kathryn E.

    2009-09-01

    A critical unknown in use of barrier technology for long-term waste isolation is performance after a major disturbance especially when institutional controls are intact, but there are no resources to implement corrective actions. The objective of this study was to quantify the effects of wild fire on alterations the function of an engineered barrier. A controlled burn September 26, 2008 was used to remove all the vegetation from the north side of the barrier. Flame heights exceeded 9 m and temperatures ranged from 250 oC at 1.5 cm below the surface to over 700 oC at 1 m above the surface. Post-fire analysis of soil properties show significant decreases in wettability, hydraulic conductivity, air entry pressure, organic matter, and porosity relative to pre-fire conditions whereas dry bulk density increased. Decreases in hydraulic conductivity and wettabilty immediately after the fire are implicated in a surface runoff event that occurred in January 2009, the first in 13 years. There was a significant increase in macro-nutrients, pH, and electrical conductivity. After one year, hydrophobicity has returned to pre-burn levels with only 16% of samples still showing signs of decreased wettability. Over the same period, hydraulic conductivity and air entry pressure returned to pre-burn levels at one third of the locations but remained identical to values recorded immediately after the fire at the other two thirds. Soil nutrients, pH, and electrical conductivity remain elevated after 1 year. Species composition on the burned surface changed markedly from prior years and relative to the unburned surface and two analog sites. An increase in the proportion of annuals and biennials is characteristic of burned surfaces that have become dominated by ruderal species. Greenhouse seedling emergence tests conducted to assess the seed bank of pre- and post-burn soils and of two analog sites at the McGee Ranch show no difference in the number of species emerging from soils collected

  19. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    International Nuclear Information System (INIS)

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-01-01

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  20. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    Energy Technology Data Exchange (ETDEWEB)

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  1. Disposal systems evaluations and tool development: Engineered Barrier System (EBS) evaluation

    International Nuclear Information System (INIS)

    Rutqvist, Jonny; Liu, Hui-Hai; Steefel, Carl I.; Serrano de Caro, M.A.; Caporuscio, Florie Andre; Birkholzer, Jens T.; Blink, James A.; Sutton, Mark A.; Xu, Hongwu; Buscheck, Thomas A.; Levy, Schon S.; Tsang, Chin-Fu; Sonnenthal, Eric; Halsey, William G.; Jove-Colon, Carlos F.; Wolery, Thomas J.

    2011-01-01

    Key components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate long-term repository performance. The focus of this report is the following: (1) Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept; (2) Evaluation of key parameters in the characterization of EBS performance; (3) Identification of key knowledge gaps and uncertainties; and (4) Evaluation of tools and modeling approaches for EBS processes and performance. The above topics will be evaluated through the analysis of the following: (1) Overview of EBS concepts for various NW disposal systems; (2) Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments; (3) Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS; and (4) Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems

  2. Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny (LBNL); Liu, Hui-Hai (LBNL); Steefel, Carl I. (LBNL); Serrano de Caro, M. A. (LLNL); Caporuscio, Florie Andre (LANL); Birkholzer, Jens T. (LBNL); Blink, James A. (LLNL); Sutton, Mark A. (LLNL); Xu, Hongwu (LANL); Buscheck, Thomas A. (LLNL); Levy, Schon S. (LANL); Tsang, Chin-Fu (LBNL); Sonnenthal, Eric (LBNL); Halsey, William G. (LLNL); Jove-Colon, Carlos F.; Wolery, Thomas J. (LLNL)

    2011-01-01

    Key components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate long-term repository performance. The focus of this report is the following: (1) Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept; (2) Evaluation of key parameters in the characterization of EBS performance; (3) Identification of key knowledge gaps and uncertainties; and (4) Evaluation of tools and modeling approaches for EBS processes and performance. The above topics will be evaluated through the analysis of the following: (1) Overview of EBS concepts for various NW disposal systems; (2) Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments; (3) Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS; and (4) Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems

  3. Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2012-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

  4. Sensitivity of performance assessment of the engineered barriers to nuances of release rate criteria

    International Nuclear Information System (INIS)

    Oliver, D.L.R.

    1987-01-01

    The United States Nuclear Regulatory Commission (NRC) has established criteria for the long-term performance of proposed high-level waste repositories. As with any regulation, the criteria may be interpreted in several ways. Due to the high capital costs and the emotional political climate associated with any high-level radioactive waste repository, it is important that there be an early consensus regarding interpretations of the criteria, and what assumptions may be used to demonstrate compliance with them. This work uses analytic solutions of mass transport theory to demonstrate how sensitive performance analyses are to various nuances of the NRC release rate criterion for the engineered barriers. The analysis is directed at the proposed repository in basalt at the Hanford site in Washington State

  5. Natural analogue studies of engineered barrier materials at PNC Tokai, Japan

    International Nuclear Information System (INIS)

    Kamei, G.; Yusa, Y.; Yamagata, J.; Inoue, K.

    1991-01-01

    Long-term extrapolations concerning the safety of a nuclear waste repository cannot be satisfactorily made on the sole basis of short-term laboratory tests. Natural analogues, which are the only means by which very slow mechanisms can be identified and by which long-term predictions of models can be tested for pertinence. Our natural analogue studies for the assessment of long-term durability of engineered barrier materials are outlined. Materials of young age and with simple history are the most suitable for the studies as: 1) properties of the materials tend to deteriorate over the longer term; and 2) detailed quantitative data on the term and on the environmental conditions can be obtained. The framework of our studies includes: 1) clarification of alteration phenomena, 2) examination of the environmental conditions, and 3) support experiments. (author)

  6. Engineered Barrier System - Manufacturing, Testing and Quality Assurance. Report from a Workshop

    International Nuclear Information System (INIS)

    2004-06-01

    As part of preparations for review of future license applications, the Swedish Nuclear Power Inspectorate (SKI) organised a workshop on the engineered barrier system for the KBS-3 concept, with the focus on manufacturing, testing and quality assurance. The main purpose of the workshop was to identify critical issues in the demonstration of how long-term safety requirements could be fulfilled for the engineered barriers. The workshop included presentations related to engineered barrier manufacturing and testing held by external experts, and working group sessions to prepare questions to the Swedish Nuclear Fuel and Waste Management Co. (SKB). SKB presentations were followed by an informal questioning and discussion with SKB representatives. This report includes a presentation of the questions posed by the working groups, SKB's replies to these questions as well as a summary of the working group discussions. The conclusions and viewpoints presented in this report are those of one or several workshop participants. During the workshop many issues regarding manufacturing, testing and quality assurance of the engineered barriers were discussed. The central themes in the questions and discussions are summarised as follows: There is a need to specify how the functional requirements for the buffer and backfill will be achieved in practise. Issues of particular interest are material selection, compaction density, initial water content and manufacturing methods for bentonite blocks. A major problem that must be addressed is the long period required to obtain relevant results from large-scale testing. The uncertainties relating to the wetting and subsequent swelling processes of the bentonite buffer have implications for analysis of the canister. It is necessary to know now non-uniform the bentonite swelling pressure could be in a worst case pressure differential, in order to evaluate the sufficiency of 'as tested' canister performance. Regarding the copper shell of the

  7. Biomimetic thermal barrier coating in jet engine to resist volcanic ash deposition

    Science.gov (United States)

    Song, Wenjia; Major, Zsuzsanna; Schulz, Uwe; Muth, Tobias; Lavallée, Yan; Hess, Kai-Uwe; Dingwell, Donald B.

    2017-04-01

    The threat of volcanic ash to aviation safety is attracting extensive attention when several commercial jet aircraft were damaged after flying through volcanic ash clouds from the May 1980 eruptions of Mount St. Helen in Washington, U.S. and especially after the air traffic disruption in 2010 Eyjafjallajökull eruption. A major hazard presented by volcanic ash to aircraft is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Due to the fact ash has a lower melting point, around 1100 °C, than the gas temperature in the hot section (between 1400 to 2000 °C), this cause the ash to melt and potentially stick to the internal components (e.g., combustor and turbine blades), this cause the ash to melt and potentially stick to the internal components of the engine creating, substantial damage or even engine failure after ingestion. Here, inspiring form the natural surface of lotus leaf (exhibiting extreme water repellency, known as 'lotus effect'), we firstly create the multifunctional surface thermal barrier coatings (TBCs) by producing a hierarchical structure with femtosecond laser pulses. In detail, we investigate the effect of one of primary femtosecond laser irradiation process parameter (scanning speed) on the hydrophobicity of water droplets onto the two kinds of TBCs fabricated by electron-beam physical vapor deposition (EB-PVD) and air plasma spray (APS), respectively as well as their corresponding to morphology. It is found that, comparison with the original surface (without femtosecond laser ablation), all of the irradiated samples demonstrate more significant hydrophobic properties due to nanostructuring. On the basis of these preliminary room-temperature results, the wettability of volcanic ash droplets will be analysed at the high temperature to constrain the potential impact of volcanic ash on the jet engines.

  8. Break-up of Ca-montmorillonite particles by Na-montmorillonite

    International Nuclear Information System (INIS)

    Hedstroem, Magnus; Birgersson, Martin

    2012-01-01

    Document available in extended abstract form only. In the Swedish KBS-3 concept for a geological deep storage of spent nuclear fuel, bentonite of high montmorillonite content is proposed to serve as a buffer surrounding copper canisters containing the spent fuel. Montmorillonite has an exceptional affinity for water which results in the build-up of a swelling pressure when bentonite is placed in a confined volume. However, there is a concern that during and after a glaciation, meltwater of low ionic strength may cause the bentonite to swell extensively into fractures and turn into a sol that could be transported away by the seeping water. It is thus warranted to understand the behaviour of montmorillonite at aqueous condition of low ionic strength. Turbidity measurements were used to a large extent in previous work to follow the free swelling or settling process of montmorillonite in various aqueous solutions and thereby give information regarding sol formation. From theory we know that turbidity of a suspension is proportional to the particle concentration. However turbidity is also proportional to V p 2 where V p is the volume of the scattering particle. Thus the fact that turbidity of a Ca-montmorillonite suspension is higher than the turbidity of a Na- montmorillonite suspension of the same clay concentration indicates that Na-montmorillonite separate into smaller particles than Ca-montmorillonite. In this work we make use this size dependence to quantify the difference between Wyoming, Milos and Kutch montmorillonite in particular with respect to how mixed Ca/Na montmorillonite systems behave. Some Ca/Mg, Mg/Na and Na/K systems are also included for comparison. Figure 1 shows the final (stabilized) turbidity response of mixed Wy-Ca/Na montmorillonite as a function of the fraction of Ca 2+ in the clay. Starting material are suspensions of homo-ionic Wy-Ca and Wy-Na montmorillonite at a concentration of 1 g/l. The turbidity of the suspensions of the homo

  9. Parallax barrier engineering for image quality improvement in an autostereoscopic 3D display.

    Science.gov (United States)

    Kim, Sung-Kyu; Yoon, Ki-Hyuk; Yoon, Seon Kyu; Ju, Heongkyu

    2015-05-18

    We present a image quality improvement in a parallax barrier (PB)-based multiview autostereoscopic 3D display system under a real-time tracking of positions of a viewer's eyes. The system presented exploits a parallax barrier engineered to offer significantly improved quality of three-dimensional images for a moving viewer without an eyewear under the dynamic eye tracking. The improved image quality includes enhanced uniformity of image brightness, reduced point crosstalk, and no pseudoscopic effects. We control the relative ratio between two parameters i.e., a pixel size and the aperture of a parallax barrier slit to improve uniformity of image brightness at a viewing zone. The eye tracking that monitors positions of a viewer's eyes enables pixel data control software to turn on only pixels for view images near the viewer's eyes (the other pixels turned off), thus reducing point crosstalk. The eye tracking combined software provides right images for the respective eyes, therefore producing no pseudoscopic effects at its zone boundaries. The viewing zone can be spanned over area larger than the central viewing zone offered by a conventional PB-based multiview autostereoscopic 3D display (no eye tracking). Our 3D display system also provides multiviews for motion parallax under eye tracking. More importantly, we demonstrate substantial reduction of point crosstalk of images at the viewing zone, its level being comparable to that of a commercialized eyewear-assisted 3D display system. The multiview autostereoscopic 3D display presented can greatly resolve the point crosstalk problem, which is one of the critical factors that make it difficult for previous technologies for a multiview autostereoscopic 3D display to replace an eyewear-assisted counterpart.

  10. Anticipated Degradation Modes of Metallic Engineered Barriers for High-Level Nuclear Waste Repositories

    Science.gov (United States)

    Rodríguez, Martín A.

    2014-03-01

    Metallic engineered barriers must provide a period of absolute containment to high-level radioactive waste in geological repositories. Candidate materials include copper alloys, carbon steels, stainless steels, nickel alloys, and titanium alloys. The national programs of nuclear waste management have to identify and assess the anticipated degradation modes of the selected materials in the corresponding repository environment, which evolves in time. Commonly assessed degradation modes include general corrosion, localized corrosion, stress-corrosion cracking, hydrogen-assisted cracking, and microbiologically influenced corrosion. Laboratory testing and modeling in metallurgical and environmental conditions of similar and higher aggressiveness than those expected in service conditions are used to evaluate the corrosion resistance of the materials. This review focuses on the anticipated degradation modes of the selected or reference materials as corrosion-resistant barriers in nuclear repositories. These degradation modes depend not only on the selected alloy but also on the near-field environment. The evolution of the near-field environment varies for saturated and unsaturated repositories considering backfilled and unbackfilled conditions. In saturated repositories, localized corrosion and stress-corrosion cracking may occur in the initial aerobic stage, while general corrosion and hydrogen-assisted cracking are the main degradation modes in the anaerobic stage. Unsaturated repositories would provide an oxidizing environment during the entire repository lifetime. Microbiologically influenced corrosion may be avoided or minimized by selecting an appropriate backfill material. Radiation effects are negligible provided that a thick-walled container or an inner shielding container is used.

  11. NASA GSFC Science Communication Working Group: Addressing Barriers to Scientist and Engineer Participation in Education and Public Outreach Activities

    Science.gov (United States)

    Bleacher, L.; Hsu, B. C.; Campbell, B. A.; Hess, M.

    2011-12-01

    The Science Communication Working Group (SCWG) at NASA Goddard Space Flight Center (GSFC) has been in existence since late 2007. The SCWG is comprised of education and public outreach (E/PO) professionals, public affairs specialists, scientists, and engineers. The goals of the SCWG are to identify barriers to scientist and engineer engagement in E/PO activities and to enable those scientists and engineers who wish to contribute to E/PO to be able to do so. SCWG members have held meetings with scientists and engineers across GSFC to determine barriers to their involvement in E/PO. During these meetings, SCWG members presented examples of successful, ongoing E/PO projects, encouraged active research scientists and engineers to talk about their own E/PO efforts and what worked for them, discussed the E/PO working environment, discussed opportunities for getting involved in E/PO (particularly in high-impact efforts that do not take much time), handed out booklets on effective E/PO, and asked scientists and engineers what they need to engage in E/PO. The identified barriers were consistent among scientists in GSFC's four science divisions (Earth science, planetary science, heliophysics, and astrophysics). Common barriers included 1) lack of time, 2) lack of funding support, 3) lack of value placed on doing E/PO by supervisors, 4) lack of training on doing appropriate/effective E/PO for different audiences, 5) lack of awareness and information about opportunities, 6) lack of understanding of what E/PO really is, and 7) level of effort required to do E/PO. Engineers reported similar issues, but the issues of time and funding support were more pronounced due to their highly structured work day and environment. Since the barriers were identified, the SCWG has taken a number of steps to address and rectify them. Steps have included holding various events to introduce scientists and engineers to E/PO staff and opportunities including an E/PO Open House, brown bag seminars on

  12. Aggregation and transport of rutile titanium dioxide nanoparticles with montmorillonite and diatomite in the presence of phosphate in porous sand.

    Science.gov (United States)

    Guo, Peng; Xu, Nan; Li, Duo; Huangfu, Xinxing; Li, Zuling

    2018-08-01

    Crop soil is inevitably contaminated by the excess of phosphate (P) fertilizers. A large amount of nanoparticle titanium dioxide (nTiO 2 ) entered soils as well due to the wide use of engineered nanomaterials. It is of great urgency and a high priority to investigate the mechanisms of nTiO 2 deposition with the presence of P in crop soils. This study investigated the transport behavior of (1.0 g L -1 ) rutile nTiO 2 with two representative clay particles (montmorillonite or diatomite) in the presence of P through the saturated quartz sand. In 10 mM NaCl electrolyte solution at pH 6.0, the recovery percentage of nTiO 2 was 36.3% from sand column. Nevertheless, it was reduced to 18.6% and 11.1% while montmorillonite and diatomite present in suspensions, respectively. Obviously, the improvement of nTiO 2 retention in sand was more pronounced by diatomite than montmorillonite. The likely mechanism for this result was that large aggregates were formed due to the attachment of nTiO 2 to montmorillonite and diatomite. Moreover, the surface of diatomite with the larger hydrodynamic radius was less negatively charged by comparison with montmorillonite. However, this phenomenon disappeared with the addition of P. P adsorption increases the repulsive force between particles and sand and the fast release of attached nTiO 2 -montmorillonite and diatomite from sand. The two-site kinetic retention model and the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory suggested that the combination of k 1/ k 1d , k 2 and secondary minimum energy can be used to accurately describe the attachment of nTiO 2 -montmorillonite and diatomite to sand in the presence of P. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Examining E-Learning Barriers As Perceived By Faculty 
Members Of Engineering Colleges In The Jordanian Universities

    OpenAIRE

    Muhammad K. AL-ALAWNEH,

    2014-01-01

    Employing computer's technology that includes e-learning system in the field of Engineering is a vital issue which needs to be discussed. Therefore, this study purposed to examine e-learning barriers as perceived by faculty members of engineering in three major universities in Jordan (Yarmouk University, Jordan University of Science and Technology, and Al-Balqaa Applied University) in the second semester of 2012. The study's instrument was distributed to collect the data from a sam...

  14. Technology assessment guide for application of engineered sorbent barriers to low-level radioactive waste disposal sites

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, H.D.; Jones, E.O.; Depner, J.P.

    1989-06-01

    An engineered sorbent barrier (ESB) uses sorbent materials (such as activated carbon or natural zeolites) to restrict migration of radionuclides from low-level waste sites. The permeability of the ESB allows moisture to pass while the sorbent material traps or absorbs contaminants. In contrast, waste sites with impermeable barriers could fill with water, especially those waste sites in humid climates. A sorbent barrier can be a simple, effective, and inexpensive method for restricting radionuclide migration. This report provides information and references to be used in assessing the sorbent barrier technology for low-level waste disposal. The ESB assessment is based on sorbent material and soil properties, site conditions, and waste properties and inventories. These data are used to estimate the thickness of the barrier needed to meet all performance requirements for the waste site. This document addresses the following areas: (1) site information required to assess the need and overall performance of a sorbent barrier; (2) selection and testing of sorbent materials and underlying soils; (3) use of radionuclide transport models to estimate the required barrier thickness and long-term performance under a variety of site conditions; (4) general considerations for construction and quality assurance; and (5) cost estimates for applying the barrier. 37 refs., 6 figs., 2 tabs.

  15. Exploring Barriers to Medication Safety in an Ethiopian Hospital Emergency Department: A Human Factors Engineering Approach

    Directory of Open Access Journals (Sweden)

    Ephrem Abebe

    2018-02-01

    Full Text Available Objective: To describe challenges associated with the medication use process and potential medication safety hazards in an Ethiopian hospital emergency department using a human factors approach. Methods: We conducted a qualitative study employing observations and semi-structured interviews guided by the Systems Engineering Initiative for Patient Safety model of work system as an analytical framework. The study was conducted in the emergency department of a teaching hospital in Ethiopia. Study participants included resident doctors, nurses, and pharmacists. We performed content analysis of the qualitative data using accepted procedures. Results: Organizational barriers included communication failures, limited supervision and support for junior staff contributing to role ambiguity and conflict. Compliance with documentation policy was minimal. Task related barriers included frequent interruptions and work-related stress resulting from job requirements to continuously prioritize the needs of large numbers of patients and family members. Person related barriers included limited training and work experience. Work-related fatigue due to long working hours interfered with staff’s ability to document and review medication orders. Equipment breakdowns were common as were non-calibrated or poorly maintained medical devices contributing to erroneous readings. Key environment related barriers included overcrowding and frequent interruption of staff’s work. Cluttering of the work space compounded the problem by impeding efforts to locate medications, medical supplies or medical charts. Conclusions: Applying a systems based approach allows a context specific understanding of medication safety hazards in EDs from low-income countries. When developing interventions to improve medication and overall patient safety, health leaders should consider the interactions of the different factors. Conflict of Interest We declare no conflicts of interest or

  16. Beyond Bias and Barriers: Fulfilling the Potential of Women in Academic Science and Engineering

    Science.gov (United States)

    Agogino, Alice

    2007-04-01

    Review of the report by the National Academies, with a focus on action strategies in the physical sciences. Women face barriers to hiring and promotion in research universities in many fields of science and engineering; a situation that deprives the United States of an important source of talent as the country faces increasingly stiff global competition in higher education, science and technology, and the marketplace. Eliminating gender bias in universities requires immediate, overarching reform and decisive action by university administrators, professional societies, government agencies, and Congress. Forty years ago, women made up only 3 percent of America's scientific and technical workers, but by 2003 they accounted for nearly one-fifth. In addition, women have earned more than half of the bachelor's degrees awarded in science and engineering since 2000. However, their representation on university and college faculties fails to reflect these gains. Among science and engineering Ph.D.s, four times more men than women hold full-time faculty positions. And minority women with doctorates are less likely than white women or men of any racial or ethnic group to be in tenure positions. The report urges higher education organizations and professional societies to form collaborative, self-monitoring body that would recommend standards for faculty recruitment, retention, and promotion; collect data; and track compliance across institutions. A ``report card'' template is provided in the report. To read the report online, add a comment, or purchase hard copy, go to: http://www.engineeringpathway.com/ep/learningresource/summary/index.jhtml?id=94A4929D-F1B2-432E-8167-63335569CB4E.

  17. Frictional strength of wet and dry montmorillonite

    Science.gov (United States)

    Morrow, C. A.; Moore, D. E.; Lockner, D. A.

    2017-05-01

    Montmorillonite is a common mineral in fault zones, and its low strength relative to other common gouge minerals is important in many models of fault rheology. However, the coefficient of friction, μ, varies with degree of saturation and is not well constrained in the literature due to the difficulty of establishing fully drained or fully dried states in the laboratory. We measured μ of both saturated and oven-dried montmorillonite at normal stresses up to 700 MPa. Care was taken to shear saturated samples slowly enough to avoid pore fluid overpressure. For saturated samples, μ increased from 0.10 to 0.28 with applied effective normal stress, while for dry samples μ decreased from 0.78 to 0.45. The steady state rate dependence of friction, (a - b), was positive, promoting stable sliding. The wide disparity in reported frictional strengths can be attributed to experimental procedures that promote differing degrees of partial saturation or overpressured pore fluid conditions.

  18. Evaluation of Thermal Barrier and PS-200 Self-Lubricating Coatings in an Air-Cooled Rotary Engine

    Science.gov (United States)

    Moller, Paul S.

    1995-01-01

    This project provides an evaluation of the feasibility and desirability of applying a thermal barrier coating overlaid with a wear coating on the internal surfaces of the combustion area of rotary engines. Many experiments were conducted with different combinations of coatings applied to engine components of aluminum, iron and titanium, and the engines were run on a well-instrumented test stand. Significant improvements in specific fuel consumption were achieved and the wear coating, PS-200, which was invented at NASA's Lewis Research Center, held up well under severe test conditions.

  19. Adsorption of ferrous ions onto montmorillonites

    Science.gov (United States)

    Qin, Dawei; Niu, Xia; Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao

    2015-04-01

    The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe2+/Fetotal ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG0 and ΔH0 were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  20. Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

    International Nuclear Information System (INIS)

    Saha, A.R.; Chattopadhyay, S.; Bose, C.; Maiti, C.K.

    2005-01-01

    Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region

  1. Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

    Energy Technology Data Exchange (ETDEWEB)

    Saha, A.R. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)]. E-mail: ars.iitkgp@gmail.com; Chattopadhyay, S. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India); School of Electrical, Electronics and Computer Engineering, University of Newcastle, Newcastle upon Tyne (United Kingdom); Bose, C. [Department of Electronics and Telecommunication Engineering, Jadavpur University, Calcutta 700032 (India); Maiti, C.K. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)

    2005-12-05

    Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region.

  2. Small scale model and underground laboratory study of engineered barrier thermal behaviour

    International Nuclear Information System (INIS)

    Dardaine, M.; Beziat, A.; Gatabin, C.; Lefevre, I.; Plas, F.; Fontan, N.; Moyne, C.

    1991-01-01

    This is the final report of the contract CCE FI1W/0061, which had the objective of studying the thermal behaviour of the engineered barrier having the selected French clay Fo-Ca (natural calcic smectite) as its major constituent. After being installed this barrier was subjected simultaneously to the heat flux dissipated by the container and to a possible rehydration by contact with the host medium. It consists of three parts. The first part is devoted to R and D studies concerning detectors suitable for the point measurement of the water concentration. Among the techniques that can be envisaged, capacitor methods, which are very temperature sensitive, would require a great deal of effort to be satisfactory. On the other hand, the water concentration can, in principle, be derived from the measurement of the thermal conductivity in the transient regime. Although the carrying out of this measurement is somewhat critical, it can give good results under certain conditions. The second part reports experiments carried out in the laboratory concerning both the study of heat transfer during the so-called dry phase of the disposal (without any water being supplied externally) and the study of the phenomenon of fissuration. Finally, the third part describes the in situ experiment BACCHUS, carried out in the underground test facility at Mol (Belgium), in collaboration with the CEN/SCK. In the course of the five months of the thermal phase of this experiment a large variation in the amplitude of the temperature gradients was recorded, which may be explained, on one hand, by the convergence of the medium and, on the other hand, by a much more rapid rehydration than that predicted

  3. Clays in natural and engineered barriers for radioactive waste confinement - 5. International meeting. Book of abstracts

    International Nuclear Information System (INIS)

    2012-10-01

    The purpose of this fifth international meeting is to bring again together specialists in the different disciplines related to clays and clay minerals, with scientists from organizations engaged in disposal of radioactive waste in order to evaluate the progress of the research conducted in that field. Multidisciplinary approaches including geology, mineralogy, geochemistry, rheology, physics and chemistry of clay minerals and assemblages are required in order to provide a detailed characterization of the geological host formations considered for the disposal of radioactive waste and to assess the behaviour of engineered and natural barriers when submitted to various types of perturbations induced by such facilities. The evaluation of the performances of the natural barrier as well as of the impact of repository-induced disturbances upon the confinement properties of clay-rich geological formations constitute major objectives for the experimental programs being and/or to be conducted in underground research laboratories, for interpreting the subsequent scientific results, for modelling the long-term behaviour of radioactive waste repositories and carrying out safety assessment exercises. The meeting covers all the aspects of clay characterization and behaviour considered at various times and space scales relevant to confinement of radionuclides in clay from basic phenomenological processes description, to the global understanding of the performance and safety at repository and geological scales. Special emphasis will be put on the modelling of processes occurring at the mineralogical level within the clay barriers. The topics covered by the program of the meeting are also supposed to be coherent with the general objectives proposed within the Strategic Research Agenda elaborated through the Implementing Geological Disposal of Radioactive Waste Technology Platform (IGD-TP). In this context, the meeting will also offer a particular opportunity to present the more

  4. Hanford Site protective isolation surface barrier: Taking research and development to engineered application

    International Nuclear Information System (INIS)

    Myers, D.R.; Wing, N.R.

    1994-01-01

    The development of the Protective Isolation Surface Barrier has been an ongoing program since 1985. This development effort has focused on several technical areas. These technical areas include water infiltration, biointrusion, human intrusion, erosion/deposition, physical stability, barrier materials, computer modeling, long-term climate effects, natural analogs, and barrier design. This paper briefly reviews the results of the research and development in the technical areas and then explains how the results of this work have influenced the design features of the prototype barrier. A good example of this is to explain how the type and depth of the soil layer used in the barrier is related to water infiltration, biointrusion, modeling, climate, analogs, and barrier materials. Another good example is to explain the relationship of the barrier sideslopes (basalt riprap and native soil) with human intrusion, biointrusion, barrier materials, and barrier design. In general, the design features of the prototype barrier will be explained in terms of the results of the testing and development program. After the basis for prototype barrier design has been established, the paper will close by reviewing the construction of the prototype barrier, sharing the lessons learned during construction, and explaining the ongoing testing and monitoring program which will determine the success or failure of this barrier concept and the need for additional design modifications

  5. Experimental methodology to study radionuclide sorption and migration in geological formations and engineered barriers of waste repositories

    International Nuclear Information System (INIS)

    Rojo Sanz, H.

    2010-01-01

    In Spain, the waste management options include either the possibility of a final storage in a deep geological repository (DGR) or the centralized temporal surface disposal (CTS). DGRs are based in a multi-barrier concept with the geological barrier and including the vitrified waste, the metal containers and engineered barriers such as compacted bentonite and cement-based materials. On the other hand, CTS mainly considers concrete and cement to confine the metal canisters containing the waste. Radionuclide migration will mainly take place by the existence of chemical concentration gradients being thus diffusion the main transport mechanism or by the existence of hydraulic gradients due to the existence of water-conductive fractures. Radionuclide sorption/retention on the materials composing the natural and engineered barriers is the fundamental process controlling contaminant migration. The evaluation of sorption parameters and the understanding of the different mechanisms leading to radionuclide retention are very important issues. The study of diffusion processes is very relevant as well. This paper describes the main experimental methodologies applied to analyse radionuclide transport in the different barriers of radioactive repositories. Particularly we focused on obtaining of retention parameters as distribution coefficients, kd, or retardation factors, Rf, and diffusion coefficients of radionuclides. (Author) 6 refs.

  6. Efficacy of backfilling and other engineered barriers in a radioactive waste repository in salt

    International Nuclear Information System (INIS)

    Claiborne, H.C.

    1982-09-01

    In the United States, investigation of potential host geologic formations was expanded in 1975 to include hard rocks. Potential groundwater intrusion is leading to very conservative and expensive waste package designs. Recent studies have concluded that incentives for engineered barriers and 1000-year canisters probably do not exist for reasonable breach scenarios. The assumption that multibarriers will significantly increase the safety margin is also questioned. Use of a bentonite backfill for surrounding a canister of exotic materials was developed in Sweden and is being considered in the US. The expectation that bentonite will remain essentially unchanged for hundreds of years for US repository designs may be unrealistic. In addition, thick bentonite backfills will increase the canister surface temperature and add much more water around the canister. The use of desiccant materials, such as CaO or MgO, for backfilling seems to be a better method of protecting the canister. An argument can also be made for not using backfill material in salt repositories since the 30-cm-thick space will provide for hole closure for many years and will promote heat transfer via natural convection. It is concluded that expensive safety systems are being considered for repository designs that do not necessarily increase the safety margin. It is recommended that the safety systems for waste repositories in different geologic media be addressed individually and that cost-benefit analyses be performed

  7. Technical basis and programmatic requirements for Engineered Barrier System Field Tests

    International Nuclear Information System (INIS)

    Lin, Wunan.

    1992-11-01

    The purpose of this study plant is to describe tests known as Engineered Barrier System Field Tests (EBSFT), which are to be conducted in the Exploratory Study Facility (ESF) at Yucca Mountain, Nevada. The EBSFT is designed to provide information on the interaction between waste packages (simulated by heated containers), the surrounding rock mass, and its vadose water. The Yucca Mountain site is being characterized to determine its suitability as a potential deep geological repository for high-level nuclear waste. Water is the main medium by which radioactive nuclides travel to the accessible environment. Therefore, the movement of water over the approximate 10,000--year lifetime required for radioactive nuclide decay must be understood. Development of a repository and emplacement of nuclear wastes impose stress loadings on the repository rock mass. The stress loadings include (1) thermal energy and irradiation from the waste packages, and (2) mechanical stress due to the mining of openings, and the transporting of waste canisters. The influence f the thermal stress may extend to all lithological units, including the saturated zone under the ground water table, in Yucca Mountain. In general, the purpose of this study is to investigate the movement of water in the rock mass under the influence of the thermal loading of the waste packages. Specifically, the study will investigate heat flow mechanism, relationship between boiling and dry-out, and the rewetting of the dry-out region when the repository is cooled down

  8. Deformation stresses and mechanical behaviour of engineered barriers in the repository environment

    International Nuclear Information System (INIS)

    Ipatti, A.; Majamaeki, O.

    1991-12-01

    The report surveys functioning of the engineered barriers in the Loviisa repository under deformation stresses of the solidification product and the concrete filling material. The survey is based on the latest estimates of the waste amounts and the corresponding repository plans, and on solidification product compositions and properties. The IVOFEM and NASTRAN software was used in the structural analyses. The materials were supposed to be homogeneous and linearly elastic and dislocations small. Accordingly, the design loads were chosen conservatively so that the impacts of deformation stresses are sufficiently overestimated. A reinforced concrete container lined with cellular plastic remains a watertight structure, meeting the requirements set in view of expansion of a solidification product. In view of the stresses, the decisive time is the intermediate storage stage. The greatest stresses are found in junctions between the container wall and the bottom and cover. The concrete filling between the waste packages cannot resist the drying shrinkage and wetting expansion stresses without cracking. Concrete walls of the repository can withstand the stress caused by wetting expansion of the waste packages only when strongly reinforced. However, the forces against the walls are so big that if cracks in the concrete walls are desired to be restricted, due to reinforcement steel corrosion or wall tightness, the present type of filling material between the waste packages is not necessarily technically the best alternative

  9. Focused feasibility study of engineered barriers for waste management units in the 200 areas

    International Nuclear Information System (INIS)

    1996-08-01

    This Focused Feasibility Study (FFS) evaluates a total of four conceptual barrier designs for different types of waste sites. The Hanford Barrier, the Modified RCRA Subtitle C Barrier, and the Modified RCRA Subtitle D Barrier are being considered as the baseline design for the purpose of the FFS evaluation. A fourth barrier design, the Standard RCRA Subtitle C Barrier, is also evaluated in this FFS; it is commonly applied at other waste sites across the country. These four designs provide a range of cover options to minimize health and environmental risks associated with a site and specific waste categories for active design life periods of 30, 100, 500, and 1,000 years. Design criteria for the 500 and 1,000-year design life barriers include design performance to extend beyond active institutional control and monitoring periods

  10. Novel applications of locally sourced montmorillonite (MMT) clay as ...

    African Journals Online (AJOL)

    This work explores the application of a locally sourced raw material, montmorillonite (MMT) clay, as a disintegrant in the formulation of an analgesic pharmaceutical product - paracetamol. The raw MMT was refined and treated with 0.IM NaCl to yield sodium montmorillonite (NaMMT) and the powder properties established in ...

  11. Performance of engineered barrier materials in near surface disposal facilities for radioactive waste. Results of a co-ordinated research project

    International Nuclear Information System (INIS)

    2001-11-01

    The primary objectives of the CRP were to: promote the sharing of experiences of the Member States in their application of engineered barrier materials for near surface disposal facilities; help enhance their use of engineered barriers by improving techniques and methods for selecting, planning and testing performance of various types of barrier materials for near surface disposal facilities. The objective of this publication is to provide and overview of technical issues related to the engineered barrier systems and a summary of the major findings of each individual research project that was carried out within the framework of the CRP. This publication deals with a general overview of engineered barriers in near surface disposal facilities, key technical information obtained within the CRP and overall conclusions and recommendations for future research and development activities. Appendices presenting individual research accomplishments are also provided. Each of the 13 appendices was indexed separately

  12. Prebiotic RNA Synthesis by Montmorillonite Catalysis

    Directory of Open Access Journals (Sweden)

    Sohan Jheeta

    2014-08-01

    Full Text Available This review summarizes our recent findings on the role of mineral salts in prebiotic RNA synthesis, which is catalyzed by montmorillonite clay minerals. The clay minerals not only catalyze the synthesis of RNA but also facilitate homochiral selection. Preliminary data of these findings have been presented at the “Horizontal Gene Transfer and the Last Universal Common Ancestor (LUCA” conference at the Open University, Milton Keynes, UK, 5–6 September 2013. The objective of this meeting was to recognize the significance of RNA in LUCA. We believe that the prebiotic RNA synthesis from its monomers must have been a simple process. As a first step, it may have required activation of the 5'-end of the mononucleotide with a leaving group, e.g., imidazole in our model reaction (Figure 1. Wide ranges of activating groups are produced from HCN under plausible prebiotic Earth conditions. The final step is clay mineral catalysis in the presence of mineral salts to facilitate selective production of functional RNA. Both the clay minerals and mineral salts would have been abundant on early Earth. We have demonstrated that while montmorillonite (pH 7 produced only dimers from its monomers in water, addition of sodium chloride (1 M enhanced the chain length multifold, as detected by HPLC. The effect of monovalent cations on RNA synthesis was of the following order: Li+ > Na+ > K+. A similar effect was observed with the anions, enhancing catalysis in the following order: Cl− > Br− > I−. The montmorillonite-catalyzed RNA synthesis was not affected by hydrophobic or hydrophilic interactions. We thus show that prebiotic synthesis of RNA from its monomers was a simple process requiring only clay minerals and a small amount of salt.

  13. AN ANALYSIS OF THE THERMAL AND MECHANICAL BEHAVIOR OF ENGINEERED BARRIERS IN A HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    S. KWON

    2013-02-01

    Full Text Available Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high-level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

  14. An analysis of the thermal and mechanical behavior of engineered barriers in a high-level radioactive waste repository

    International Nuclear Information System (INIS)

    Kwon, S.; Cho, W. J.; Lee, J. O.

    2013-01-01

    Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

  15. Effect of thermal barrier coating with various blends of pumpkin seed oil methyl ester in DI diesel engine

    Science.gov (United States)

    Karthickeyan, V.; Balamurugan, P.

    2017-10-01

    The rise in oil prices, dependency on fossil fuels, degradation of non-renewable energy resources and global warming strives to find a low-carbon content alternative fuel to the conventional fuel. In the present work, Partially Stabilized Zirconia (PSZ) was used as a thermal barrier coating in piston head, cylinder head and intake and exhaust valves using plasma spray technique, which provided a rise in combustion chamber temperature. With the present study, the effects of thermal barrier coating on the blends of Pumpkin Seed Oil Methyl Ester (PSOME) were observed in both the coated and uncoated engine. Performance and emission characteristics of the PSOME in coated and uncoated engines were observed and compared. Increased thermal efficiency and reduced fuel consumption were observed for B25 and diesel in coated and uncoated engine. On comparing with the other biodiesel samples, B25 exhibited lower HC, NOx and smoke emissions in thermally coated engine than uncoated engine. After 100 h of operation, no anamolies were found in the thermally coated components except minor cracks were identified in the edges of the piston head.

  16. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

    Directory of Open Access Journals (Sweden)

    T. Karthikeya Sharma

    2015-11-01

    Full Text Available Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE. This paper investigates the effects of using argon (Ar gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied.

  17. 60Co retention by Mexican montmorillonites

    International Nuclear Information System (INIS)

    Pacheco, G.; Martinez, V.; Bosch, P.; Bulbulian, S.

    1995-01-01

    Radioactive elements may be retained by clays. The ability of natural Mexican clays to retain radioactive Co from aqueous solutions, is discussed. Experiments were performed with solutions containing labeled cobalt. The effect of contact time on Co 2+ retention was studied. It was found that the Co 2+ uptake value in dehydrated montmorillonites is between 0.30 and 0.70 meq g -1 of clay. A sorption sequence was obtained for the various clays. The samples were characterized, before and after cobalt exchange, by X-ray diffraction. (author). 7 refs., 3 figs., 3 tabs

  18. Modification of montmorillonite fillers by ionizing radiation

    International Nuclear Information System (INIS)

    Zimek, Z.; Przybytniak, G.; Nowicki, A.; Mirkowski, K.

    2006-01-01

    The mineral fillers can be modified by using unsaturated compounds: styrene, methacrylic acid and maleic anhydride (MA), following by irradiation with high energy electron beam. In presented paper the authors have used this method to change properties of bentonite S pecjal , containing about 70% of pure montmorillonite. It has been shown that: (a) the particles obtained in this process can be good fillers for the production of composites; (b) maleic anhydride reacts via anhydride group with active ionic sites of bentonite, forming a salt-like compound. Irradiation with electron beam leads to the breakage of double bond in maleic anhydride and to the production of new organic phases

  19. Degradation of surfactant-modified montmorillonites in HCl

    International Nuclear Information System (INIS)

    Madejová, Jana; Pálková, Helena; Jankovič, Ľuboš

    2012-01-01

    The effect of surfactant size on the extent of montmorillonites decomposition in HCl was investigated. Na-SAz montmorillonite and tetraalkylammonium salts of alkyl-chains length increasing from methyl- Me 4 N to pentyl- Pe 4 N were used for organo-montmorillonites preparation. Decreasing intensity of d 001 diffraction proved destruction of montmorillonite structure connected with gradual surfactant release. A shift of the SiO stretching band to 1097 cm −1 confirmed formation of amorphous silica phase. A new band near 7315 cm −1 corresponding to SiOH overtone revealed creation of protonated silica. This band was observed in the spectra of all acid-treated samples, also in those with minor decomposition of the structure. The size of the cations significantly affected decomposition of montmorillonites in HCl. The less stable were Na-SAz and Me 4 N-SAz in which the content of octahedral atoms dropped to ∼5% of their original values upon 8 h treatments. Et 4 N-SAz and Pr 4 N-SAz were slightly more resistant mainly at short times. Bu 4 N-SAz and Pe 4 N-SAz showed the least structural modifications, only 50% and 35% of octahedral atoms, respectively, were released into solution within 8 h treatments. This observation proves that bulky alkylammonium cations covering the inner and outer surfaces of montmorillonite prevent effectively the access of protons to the layers protecting the mineral from degradation in the acid. - Highlights: ► Hybrid materials were prepared from montmorillonite and alkylammonium cations with short alkyl chains. ► The effect of surfactant on organo-montmorillonites dissolution in HCl was studied. ► With increasing size of cation the extent of montmorillonite decomposition decreased. ► Bulky surfactants prevent the access of protons to the layers and thus protect montmorillonite from degradation.

  20. Study of waterproof capabilities of the engineered barrier containing bentonite in near surface radioactive waste repositories

    International Nuclear Information System (INIS)

    Luu Cao Nguyen; Nguyen Ba Tien; Doan Thi Thu Hien; Nguyen Van Chinh; Vuong Huu Anh

    2017-01-01

    In Vietnam, the study of nuclear fuel cycle is in first steps, such as the exploitation and uranium processing. These processes generated large amounts of radioactive waste over-timing. The naturally occurring radioactive material and technologically enhanced radioactive material (NORM/TENORM) waste, which would be large, needs to be managed and disposed reasonably by effective methods. These wastes were used to be disposal in the near surface. It was therefore very important to study the model of radioactive waste repository, where bentonite waterproofing layer would be applied for the engineered barrier. The aim of this study was to obtain the preliminary parameters for low-level radioactive waste disposal site being suitable with the conditions of Vietnam. The investigation of the ratio between soil and bentonite was taken part. The experiments with some layers of waterproofing material with the ratio of soil and bentonite as 75/25, 50/50 and 25/75 were carried out to test the moving of uranium nuclide through these waterproofing material layers. Analyzing the uranium content in each layer (0.1 cm) of pressed soil - bentonite mixture (as a block) to determine the uranium nuclide adsorption from solution into the materials in the different ratios at the different times: 1, 2 and 3 months was carried out. The results showed that the calculated average rate of uranium nuclide migration into the soil - bentonite layer was 5.4x10 -10 , 5.4x10 -10 and 3.85x10 -10 m/s corresponding to the waterproofing layer thickness (for 300 years) 4.86 m, 4.86 m and 3.63 m respectively, which was due on the ratio of soil and bentonite 75/25, 50/50, 25/75 to keep the safety for the repository. (author)

  1. Technical Work Plan for: Near Field Environment: Engineered Barrier System: Radionuclide Transport Abstraction Model Report

    International Nuclear Information System (INIS)

    J.D. Schreiber

    2006-01-01

    This technical work plan (TWP) describes work activities to be performed by the Near-Field Environment Team. The objective of the work scope covered by this TWP is to generate Revision 03 of EBS Radionuclide Transport Abstraction, referred to herein as the radionuclide transport abstraction (RTA) report. The RTA report is being revised primarily to address condition reports (CRs), to address issues identified by the Independent Validation Review Team (IVRT), to address the potential impact of transport, aging, and disposal (TAD) canister design on transport models, and to ensure integration with other models that are closely associated with the RTA report and being developed or revised in other analysis/model reports in response to IVRT comments. The RTA report will be developed in accordance with the most current version of LP-SIII.10Q-BSC and will reflect current administrative procedures (LP-3.15Q-BSC, ''Managing Technical Product Inputs''; LP-SIII.2Q-BSC, ''Qualification of Unqualified Data''; etc.), and will develop related Document Input Reference System (DIRS) reports and data qualifications as applicable in accordance with prevailing procedures. The RTA report consists of three models: the engineered barrier system (EBS) flow model, the EBS transport model, and the EBS-unsaturated zone (UZ) interface model. The flux-splitting submodel in the EBS flow model will change, so the EBS flow model will be validated again. The EBS transport model and validation of the model will be substantially revised in Revision 03 of the RTA report, which is the main subject of this TWP. The EBS-UZ interface model may be changed in Revision 03 of the RTA report due to changes in the conceptualization of the UZ transport abstraction model (a particle tracker transport model based on the discrete fracture transfer function will be used instead of the dual-continuum transport model previously used). Validation of the EBS-UZ interface model will be revised to be consistent with

  2. Engineered Barrier System - Long-term Stability of Buffer and Backfill. Synthesis and extended abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Apted, Mick; Arthur, Randy [Monitor Scientific LLC, Denver, CO (United States); Savage, Dave [Quintessa Ltd., Nottingham (GB)] (eds.)

    2005-09-15

    SKI is preparing to review the license applications being developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) for an encapsulation plant and a deep repository for the geological disposal of spent nuclear fuel. As part of its preparation, SKI is conducting a series of technical workshops on key aspects of the Engineered Barrier System (EBS) of the repository. This workshop concerns the longterm stability of the buffer and the backfill. Previous workshops have addressed the overall concept for long-term integrity of the EBS, the manufacturing, testing and QA of the EBS and the performance confirmation for the EBS. The goal of this work is to achieve a comprehensive overview of all aspects of SKB's EBS work prior to the handling of forthcoming license applications. The reports from the EBS workshops will be used as one important basis in future review work. The workshops involve the gathering of a sufficient number of independent experts in different subjects of relevance to the particular aspect of EBS. A workshop starts with presentations and discussions among these experts. Following this, SKB presents recent results and responds to questions as part of an informal hearing. Finally, the independent experts and the SKI staff examine the SKB responses from different viewpoints. This report aims to summarise the issues discussed at the buffer and backfill workshop and to extract the essential viewpoints that have been expressed. The report is not a comprehensive record of the discussions and individual statements made by workshop participants should be regarded as opinions rather than proven facts. This reports includes apart from the workshop synthesis, questions to SKB identified prior or during the workshop, and extended abstracts for introductory presentations.

  3. Engineered Barrier System - Long-term Stability of Buffer and Backfill. Synthesis and extended abstracts

    International Nuclear Information System (INIS)

    Apted, Mick; Arthur, Randy; Savage, Dave

    2005-09-01

    SKI is preparing to review the license applications being developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) for an encapsulation plant and a deep repository for the geological disposal of spent nuclear fuel. As part of its preparation, SKI is conducting a series of technical workshops on key aspects of the Engineered Barrier System (EBS) of the repository. This workshop concerns the longterm stability of the buffer and the backfill. Previous workshops have addressed the overall concept for long-term integrity of the EBS, the manufacturing, testing and QA of the EBS and the performance confirmation for the EBS. The goal of this work is to achieve a comprehensive overview of all aspects of SKB's EBS work prior to the handling of forthcoming license applications. The reports from the EBS workshops will be used as one important basis in future review work. The workshops involve the gathering of a sufficient number of independent experts in different subjects of relevance to the particular aspect of EBS. A workshop starts with presentations and discussions among these experts. Following this, SKB presents recent results and responds to questions as part of an informal hearing. Finally, the independent experts and the SKI staff examine the SKB responses from different viewpoints. This report aims to summarise the issues discussed at the buffer and backfill workshop and to extract the essential viewpoints that have been expressed. The report is not a comprehensive record of the discussions and individual statements made by workshop participants should be regarded as opinions rather than proven facts. This reports includes apart from the workshop synthesis, questions to SKB identified prior or during the workshop, and extended abstracts for introductory presentations

  4. A multi-purpose unit concept to integrate storage, transportation, and the engineered barrier system

    International Nuclear Information System (INIS)

    Hollaway, W.R.; Rozier, R.; Nitti, D.A.; Williams, J.R.

    1993-01-01

    The Multi-Purpose Unit (MPU) is a new concept for standardizing and integrating the waste management functions of spent fuel storage, transportation, and geologic disposal. The MPU concept would use one unit, composed of a relatively thick-walled inner canister with a multi-purpose overpack, to meet the requirements for storage in 10 CFR 72, transportation in 10 CFR 71, and the engineered barrier system in 10 CFR 60. The MPU concept differs from the recently proposed Multi-Purpose Canister (MPC) concept in that the MPU concept uses a single multi-purpose overpack for storage, transportation, and geologic disposal, while the MPC concept uses separate and unique overpacks for each of these system functions. A design concept for the MPU is presented along with an estimate of unit costs. An initial evaluation of overall system cost showed that the MPU concept could be economically competitive with the current reference system. The MPU concept provides the potential for significant reduction, simplification, and standardization of Civilian Radioactive Waste Management (CRWMS) facilities and operations, including those at the utilities, during waste acceptance and transportation, and at the Monitored Retrievable Storage (MRS) facility and the repository. The primary issues for the MPU concept relate to uncertainties with respect to licensing, and the programmatic risks associated with implementing the MPU concept before the repository design is finalized. The strong potential exhibited by the MPU concept demonstrates that this option merits additional development and should be considered in the next phase of work on multi-purpose concepts for the CRWMS

  5. Experimental Studies of Engineered Barrier Systems Conducted at Los Alamos National Laboratory (FY16)

    Energy Technology Data Exchange (ETDEWEB)

    Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maner, James [Univ. of Oklahoma, Norman, OK (United States). School of Geology and Geophysics; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-08-04

    Over the past five years the Used Fuel Campaign has investigated Engineered Barrier Systems (EBS) at higher heat loads (up to 300°C) and pressure (150 bar). This past year experimental work was hindered due to a revamping of the hydrothermal lab. Regardless, two experiments were run this past year, EBS-18 and EBS-19. EBS-18 was run using Low Carbon Steel (LCS) and opalinus clay in addition to the bentonite and opalinus brine. Many of the past results were confirmed in EBS-18, such as the restriction of illite formation due to the bulk chemistry, pyrite degradation, and zeolite formation dependent on the bentonite and opalinus clay. The LCS show vast amounts of pit corrosion (over 100μm of corrosion in six weeks), leading a corrosion rate of 1083 μm/year. In addition, a mineral goethite, an iron-bearing hydroxide, formed in the pits of the LCS. Preliminary results from EBS-19 water chemistry are included but SEM imaging, micro probe and XRD are still needed for further results. Copper corrosion was investigated further and over 850 measurements were taken. It was concluded that pitting and pyrite degradation drastically increase the corrosion rate from 0.12 to 0.39 μm/day. However, the growth of a layer of the mineral chalcocite is thought to subdue the corrosion rate to 0.024 μm/day as observed in the EBS-13, a sixth month experiment. This document presents the findings of this past year.

  6. Women withdrawers in engineering studies : identity formation and learning culture as gendered barriers for persistence?

    OpenAIRE

    Wolffram, Andrea; Derboven, Wibke; Winker, Gabriele

    2009-01-01

    Scholarship on women in engineering education mainly focuses on the question of how to attract more women to this subject. The topic concerning women in engineering education is here guided by the question of why women leave engineering studies. The paper aims to examine the main conflicts women encounter in engineering education and to derive implications for interventions suited for strengthening institutional bonding forces.

  7. Nanocomposites of rice and banana flours blend with montmorillonite: Partial characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Marín, María L.; Bello-Pérez, Luis A. [Centro de Desarrollo de Productos Bióticos, Instituto Politécnico Nacional, Km 6 carr Yautepec-Jojutla, Calle Ceprobi No. 8, Colonia San Isidro, Apartado Postal 24, C.P 62731, Yautepec, Morelos (Mexico); Yee-Madeira, Hernani [Departamento de Física, Escuela Superior de Física y Matemáticas-IPN, Edificio 9, U.P., ‘Adolfo López Mateos’ Col. Lindavista, C.P. 07738, México, D. F. (Mexico); Zhong, Qixin [Department of Food science and Technology, the University of Tennessee, Knoxville (United States); González-Soto, Rosalía A., E-mail: rsoto@ipn.mx [Centro de Desarrollo de Productos Bióticos, Instituto Politécnico Nacional, Km 6 carr Yautepec-Jojutla, Calle Ceprobi No. 8, Colonia San Isidro, Apartado Postal 24, C.P 62731, Yautepec, Morelos (Mexico)

    2013-10-15

    Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. - Highlights: • Flour films presented adequate mechanical and barrier properties. • Addition of montmorillonite modified the mechanical and barrier properties of flour films. • The mechanical properties of the films were influenced by the different components of the flours. • The fiber of the banana flour improved the mechanical properties of the films.

  8. Nanocomposites of rice and banana flours blend with montmorillonite: Partial characterization

    International Nuclear Information System (INIS)

    Rodríguez-Marín, María L.; Bello-Pérez, Luis A.; Yee-Madeira, Hernani; Zhong, Qixin; González-Soto, Rosalía A.

    2013-01-01

    Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. - Highlights: • Flour films presented adequate mechanical and barrier properties. • Addition of montmorillonite modified the mechanical and barrier properties of flour films. • The mechanical properties of the films were influenced by the different components of the flours. • The fiber of the banana flour improved the mechanical properties of the films

  9. Evaluation of Subsurface Engineered Barriers at Waste Sites Volumes 1 and 2

    Science.gov (United States)

    This report provides the U.S. Environmental Protection Agency’s (EPA) waste programs with a national retrospective analysis of barrier field performance, as well as information that useful in developing guidance on the use and evaluation of barrier systems

  10. On different photodecomposition behaviors of rhodamine B on laponite and montmorillonite clay under visible light irradiation

    KAUST Repository

    Wang, Peng

    2013-12-11

    In this study, laponite and montmorillonite clays were found to be able to decompose rhodamine B upon visible light irradiation (λ>420nm). Very interestingly, it was found that rhodamine B on laponite underwent a stepwise N-deethylation and its decomposition was terminated once rhodamine 110, as a decomposition product, was formed, whereas the same phenomenon was not observed for rhodamine B on montmorillonite, whose decomposition involved chromophore destruction. Mechanistic study revealed that the different photodecomposition behaviors of rhodamine B on laponite and montmorillonite were attributed to the oxidation by different reactive oxygen species, with laponite involving HO2/O2- while montmorillonite involving OH. It was also found that the degradation pathway of rhodamine B on laponite switched from N-deethylation to chromophore destruction when solution pH was changed from 7.0 to 3.0, which was attributed to a much higher fraction of HO2 relative to O2- under pH 3.0 than under pH 7.0. Based on the results, a mechanism of rhodamine dye decomposition on clay under visible light was proposed, involving the clay as an electron acceptor, electron relay between the adsorbed dye molecules and oxygen molecules, and subsequent reactions between the generated dye radical cations and different reactive oxygen species. The results of this study shed light on how to best utilize visible light for organic pollutant degradation on clays within engineered treatment systems as well as on many of naturally occurring pollutant degradation processes in soils and air involving clay. © 2013 King Saud University.

  11. Physicochemical and Geotechnical Alterations to MX-80 Bentonite at the Waste Canister Interface in an Engineered Barrier System

    Directory of Open Access Journals (Sweden)

    Christopher W. Davies

    2017-08-01

    Full Text Available The study investigated the basic geomechanical and mineralogical evolution of the bentonite barrier under various experimental boundary conditions which replicated the near-field Thermo-Hydro-Chemico (THC conditions in a repository. The relationships between the physicochemical alterations and changes in the geotechnical properties have seldom been studied, especially on a consistent dataset. This paper attempts to link the physicochemical properties of Na-bentonite (MX-80 to the macro-scale engineering functionality of the bentonite post THC exposure. Experiments investigated the impact of THC variables on the engineering and physicochemical functionality of the bentonite with respect to its application within a High-Level Waste (HLW engineered barrier system. Intrinsic alterations to the MX-80 bentonite under relatively short-term exposure to hydrothermal and chemical conditions were measured. Additionally, two long-term tests were conducted under ambient conditions to consider the impact of exposure duration. The intrinsic measurements were then related to the overall performance of the bentonite as a candidate barrier material for application in a UK geological disposal facility. Findings indicate that exposure to thermo-saline-corrosion conditions (i.e., corrosion products derived from structural grade 275 carbon steel inhibits the free swell capacity and plasticity of the bentonite. However, the measured values remained above the design limits set out for the Swedish multi-barrier concept, from which the UK concept may take a lead. Corrosion alone does not appear to significantly affect the geotechnical measurements compared with the influence of thermal loading and high saline pore water after relatively short-term exposure. Thermal and corrosion exposure displayed no impact on the intrinsic swelling of the smectite component, indicating that no significant structural alteration had occurred. However, when exploring more complex saline

  12. Modeling the Hydrogeochemical Transport of Radionuclides through Engineered Barriers System in the Proposed LLW Disposal Site of Taiwan - 12082

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wen-Sheng [Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan (China); Liu, Chen-Wuing; Tsao, Jui-Hsuan [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan (China); Li, Ming-Hsu [Institute of Hydrological and Oceanic Sciences, National Central University, Jhongli, Taiwan (China)

    2012-07-01

    A proposed site for final disposal of low-level radioactive waste located in Daren Township of Taitung County along the southeastern coast has been on the selected list in Taiwan. The geology of the Daren site consists of argillite and meta-sedimentary rocks. A mined cavern design with a tunnel system of 500 m below the surface is proposed. Concrete is used as the main confinement material for the engineered barrier. To investigate the hydrogeochemical transport of radionuclides through engineered barriers system, HYDROGEOCHEM5.0 model was applied to simulate the complex chemical interactions among radionuclides, the cement minerals of the concrete, groundwater flow, and transport in the proposed site. The simulation results showed that the engineered barriers system with the side ditch efficiently drained the ground water and lowered the concentration of the concrete degradation induced species (e.g., hydrogen ion, sulfate, and chloride). The velocity of groundwater observed at side ditch gradually decreased with time due to the fouling of pore space by the mineral formation of ettringite and thaumasite. The short half-life of Co-60, Sr-90 and Cs-137 significantly reduced the concentrations, whereas the long half-life of I-129(1.57x10{sup 7} years) and Am-241(432 years) remain stable concentrations at the interface of waste canister and concrete barrier after 300 years. The mineral saturation index (SI) was much less than zero due to the low aqueous concentration of radionuclide, so that the precipitation formation of Co-60, Sr-90, I-129, Cs-137 and Am-241 related minerals were not found. The effect of adsorption/desorption (i.e., surface complexation model) could be a crucial geochemical mechanism for the modeling of liquid-solid phase behavior of radionuclide in geochemically dynamic environments. Moreover, the development of advanced numerical models that are coupled with hydrogeochemical transport and dose assessment of radionuclide is required in the future

  13. Combined Effects of JP-8 Fuel and Ceramic Thermal Barrier Coatings on the Performance and Emissions of a DI Diesel Engine

    National Research Council Canada - National Science Library

    Klett, David

    1999-01-01

    .... The experiments were conducted on a Ricardo Hydra single-cylinder DI diesel engine. Thin ceramic thermal barrier coatings were applied to various combustion chamber surfaces including the piston crown, cylinder head, and cylinder liner...

  14. Use of radial basis functions for meshless numerical solutions applied to financial engineering barrier options

    Directory of Open Access Journals (Sweden)

    Gisele Tessari Santos

    2009-08-01

    Full Text Available A large number of financial engineering problems involve non-linear equations with non-linear or time-dependent boundary conditions. Despite available analytical solutions, many classical and modified forms of the well-known Black-Scholes (BS equation require fast and accurate numerical solutions. This work introduces the radial basis function (RBF method as applied to the solution of the BS equation with non-linear boundary conditions, related to path-dependent barrier options. Furthermore, the diffusional method for solving advective-diffusive equations is explored as to its effectiveness to solve BS equations. Cubic and Thin-Plate Spline (TPS radial basis functions were employed and evaluated as to their effectiveness to solve barrier option problems. The numerical results, when compared against analytical solutions, allow affirming that the RBF method is very accurate and easy to be implemented. When the RBF method is applied, the diffusional method leads to the same results as those obtained from the classical formulation of Black-Scholes equation.Muitos problemas de engenharia financeira envolvem equações não-lineares com condições de contorno não-lineares ou dependentes do tempo. Apesar de soluções analíticas disponíveis, várias formas clássicas e modificadas da conhecida equação de Black-Scholes (BS requerem soluções numéricas rápidas e acuradas. Este trabalho introduz o método de função de base radial (RBF aplicado à solução da equação BS com condições de contorno não-lineares relacionadas a opções de barreira dependentes da trajetória. Além disso, explora-se o método difusional para solucionar equações advectivo-difusivas quanto à sua efetividade para solucionar equações BS. Utilizam-se funções de base radial Cúbica e Thin-Plate Spline (TPS, aplicadas à solução de problemas de opções de barreiras. Os resultados numéricos, quando comparados com as soluções analíticas, permitem afirmar

  15. Thermal barrier coatings: Coating methods, performance, and heat engine applications. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-01

    The bibliography contains citations concerning conference proceedings on coating methods, performance evaluations, and applications of thermal barrier coatings as protective coatings for heat engine components against high temperature corrosions and chemical erosions. The developments of thermal barrier coating techniques for high performance and reliable gas turbines, diesel engines, jet engines, and internal combustion engines are presented. Topics include plasma sprayed coating methods, yttria stabilized zirconia coatings, coating life models, coating failure and durability, thermal shock and cycling, and acoustic emission analysis of coatings. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  16. Thermal barrier coatings: Coating methods, performance, and heat engine applications. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-01

    The bibliography contains citations concerning conference proceedings on coating methods, performance evaluations, and applications of thermal barrier coatings as protective coatings for heat engine components against high temperature corrosions and chemical erosions. The developments of thermal barrier coating techniques for high performance and reliable gas turbines, diesel engines, jet engines, and internal combustion engines are presented. Topics include plasma sprayed coating methods, yttria stabilized zirconia coatings, coating life models, coating failure and durability, thermal shock and cycling, and acoustic emission analysis of coatings. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  17. PERFORMANCE ANALYSIS OF 1,4 DIOXANE-ETHANOL-DIESEL BLENDS ON DIESEL ENGINES WITH AND WITHOUT THERMAL BARRIER COATING

    Directory of Open Access Journals (Sweden)

    Chockalingam Sundar Raj

    2010-01-01

    Full Text Available 1,4 dioxane, a new additive allows the splash blending of ethanol in diesel in a clear solution. The objective of this investigation is to first create a stable ethanol-diesel blended fuel with 10% 1,4 dioxane additive, and then to generate performance, combustion and emissions data for evaluation of different ethanol content on a single cylinder diesel engine with and without thermal barrier coating. Results show improved performance with blends compared to neat fuel for all conditions of the engine. Drastic reduction in smoke density is found with the blends as compared to neat diesel and the reduction is still better for coated engine. NOx emissions were found to be high for coated engines than the normal engine for the blends. The oxygen enriched fuel increases the peak pressure and rate of pressure rise with increase in ethanol ratio and is still superior for coated engine. Heat release pattern shows higher premixed combustion rate with the blends. Longer ignition delay and shorter combustion duration are found with all blends than neat diesel fuel.

  18. Synthesis and characterization of nanohybrid of montmorillonite and zinc oxide

    International Nuclear Information System (INIS)

    Chagas, Beatriz S.; Mendes, Luis C.; Brito, Alice S.

    2009-01-01

    Zinc oxide-aluminosilicate nanohybrids through a hydrothermal reaction of a colloidal suspension of exfoliated montmorillonite nanosheets and zinc oxide in acid solution, performed in three different routes, were synthesized. The products were characterized by wide angle X-ray diffraction (WAXD). In all routes, it was found that the intercalation of zinc oxide into the host montmorillonite gallery was successfully performed so that the crystalline peaks of the montmorillonite and zinc oxide were suppressed from the X-ray patterns. The use of ultrasound decreased the reaction time.(author)

  19. Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Powell, Brian [Clemson Univ., SC (United States); Schlautman, Mark [Clemson Univ., SC (United States); Rao, Linfeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nitsche, Heino [Univ. of California, Berkeley, CA (United States); Gregorich, Kenneth [Univ. of California, Berkeley, CA (United States)

    2016-02-02

    The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gaps still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in

  20. Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

    International Nuclear Information System (INIS)

    Powell, Brian; Schlautman, Mark; Rao, Linfeng; Nitsche, Heino; Gregorich, Kenneth

    2016-01-01

    The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gaps still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in

  1. Modelling Coupled Processes in the Evolution of Repository Engineered Barrier Systems using QPAC-EBS

    Energy Technology Data Exchange (ETDEWEB)

    Maul, Philip; Benbow, Steven; Bond, Alex; Robinson, Peter (Quintessa Limited, Henley-on-Thames (United Kingdom))

    2010-08-15

    A satisfactory understanding of the evolution of repository engineered barrier systems (EBS) is an essential part of the safety case for the repository. This involves consideration of coupled Thermal (T), Hydro (H), Mechanical (M) and Chemical (C) processes. Quintessa's general-purpose modelling code QPAC is capable of representing strongly coupled non-linear processes and has been used in a wide range of applications. This code is the basis for software used by Quintessa in studies of the evolution of the EBS in a deep repository for spent nuclear fuel undertaken for SKI and then SSM since 2007. The collection of software components employed has been referred to collectively as QPAC-EBS, consisting of the core QPAC code together with relevant modules for T, H, M and C processes. QPAC-EBS employs a fundamentally different approach from dedicated codes that model such processes (although few codes can represent each type of process), enabling the specification of new processes and the associated governing equations in code input. Studies undertaken to date have demonstrated that QPAC-EBS can be used effectively to investigate both the early evolution of the EBS and important scenarios for the later evolution of the system when buffer erosion and canister corrosion may occur. A key issue for modelling EBS evolution is the satisfactory modelling of the behaviour of the bentonite buffer. Bentonite is a difficult material to model, partly because of the complex coupled mechanical, hydro and chemical processes involved in swelling during resaturation. Models employed to date have generally taken an empirical approach, but a new model developed during the EU THERESA project could be further developed to provide a better representation of these processes. QPAC-EBS could play an important role in supporting SSM.s review of the forthcoming SR-Site assessment by SKB if used by Quintessa in independent supporting calculations. To date radionuclide transport calculations

  2. Evaluating Admission Practices as Potential Barriers to Creating Equitable Access to Undergraduate Engineering Education

    Science.gov (United States)

    Myers, Beth Ann

    2016-01-01

    To create a more competitive and creative engineering workforce, breakthroughs in how we attract and educate more diverse engineers are mandated. Despite a programmatic focus on increasing the representation of women and minorities in engineering during the last few decades, no single solution has been identified and is probably not realistic. But…

  3. Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

    Science.gov (United States)

    Zhu, Dongming

    2018-01-01

    Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

  4. Caffeine adsorption of montmorillonite in coffee extracts.

    Science.gov (United States)

    Shiono, Takashi; Yamamoto, Kenichiro; Yotsumoto, Yuko; Yoshida, Aruto

    2017-08-01

    The growth in health-conscious consumers continues to drive the demand for a wide variety of decaffeinated beverages. We previously developed a new technology using montmorillonite (MMT) in selective decaffeination of tea extract. This study evaluated and compared decaffeination of coffee extract using MMT and activated carbon (AC). MMT adsorbed caffeine without significant adsorption of caffeoylquinic acids (CQAs), feruloylquinic acids (FQAs), dicaffeoylquinic acids (di-CQAs), or caffeoylquinic lactones (CQLs). AC adsorbed caffeine, chlorogenic acids (CGAs) and CQLs simultaneously. The results suggested that the adsorption selectivity for caffeine in coffee extract is higher in MMT than AC. The caffeine adsorption isotherms of MMT in coffee extract fitted well to the Langmuir adsorption model. The adsorption properties in coffee extracts from the same species were comparable, regardless of roasting level and locality of growth. Our findings suggest that MMT is a useful adsorbent in the decaffeination of a wide range of coffee extracts.

  5. ANALYSIS DEGRADATION OF POLYSTYRENE WITH MONTMORILLONITE NANOFILLERS

    Directory of Open Access Journals (Sweden)

    Maria Mihalikova

    2014-01-01

    Full Text Available The paper is focused on the experimental investigation of the montmorillonite nanofillers effect on deformation properties of polystyrene KRASTEN 171. In some cases, combination of a low amount of clay with dispersed polymeric phase may cause synergistic effects leading to very fair balance of mechanical behaviour. This seems to be a consequence of complex influencing the multiphase system by clay such as modification of components (reinforcement and parameters of the interface accompanied by influencing the dynamic phase behaviour, i.e., the compactibilizing effect. The paper analyses the effect of nanocomposites and type of the material on the individual measured parameters, relations between them, strength and deformation behaviour. Deformation was evaluated by non-contact videoextensometry method

  6. Dehydration kinetics of a natural montmorillonite

    International Nuclear Information System (INIS)

    Andreotti, G.; Loria, A.; Mazzega, E.; Valeri, S.

    1978-01-01

    The dehydration mass loss of samples of montmorillonite (a layered hydrated silicate) was measured in an environment at constant temperature and at constant undersatured water vapour content. The hydration curves were analyzed by assuming the model of thermally activated, monoenergetic and first-order process compatible with the experimental results. Two dehydration kinetics with activation energies (0.21+-0.02) eV and (0.34+-0.02) eV were found that can be related to the existence of two kinds of water (structured and nonstructured) in the hydrated silicate interlayers. The possibility of an icelike structure of a fraction of the adsorbed molecules is briefly discussed. The experimental results show, furthermore, that in the investigated hydration range (up to about 10% in mass) the fraction of structured water has a maximum when the hydration is about 6%. (author)

  7. Investigations on uranium sorption on bentonite and montmorillonite, respectively, and uranium in environmental samples; Untersuchungen zur Uransorption an Bentonit bzw. Montmorillonit sowie von Uran in Umweltproben

    Energy Technology Data Exchange (ETDEWEB)

    Azeroual, Mohamed

    2010-09-22

    The geotechnical barrier is an important component of a geological repository and consists of compacted bentonite surrounding radioactive waste containers. Its most important functions are, to retard the radionuclide migration into the biosphere and to prevent groundwater contact with containers. lt is therefore of central importance to investigate the bentonite material on its capacity to sorb radionuclides under near-natural chemical and physical conditions. The purpose of this work was to study the adsorption of uranium(VI) on bentonit and on montmorillonite-standards at high uranium concentrations. Thereby, a special account was given to the calcium-uranyl-carbonate complexation, which leads to the formation of very stable and mobile uncharged Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} complex. Results of batch experiments showed that the dicalcium-uranyl-tricarbonate complexation lowers the uranium(VI) sorption on natural clay (bentonite) by a factor of up to 3. After 21 days of contact time, about 40 % and 20 % of the initial uranium(VI)concentration were sorbed on Na-bentonite and ea-bentonite, respectively, from a solution with Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} dominating the uranium(VI) speciation. On the contrary, about 55 % of the initial uranium(VI)-concentration were sorbed on thes clays from the solution, in which (UO{sub 2}){sub 2}CO{sub 3}(OH){sub 3}{sup -} complex dominated the uranium(VI) speciation. Thus uranium(VI) sorption is more strongly influenced by the solution composition than by bentonite type. Na-bentonite should be used instead of ea-bentonite as a geotechnical barrier, since calcium-uranyl-carbonate complexation may be a realistic scenario. Further SEM-EDX and HREM-EDX studies showed that uranium(VI) sorption occurred predominantly on montmorillonite, which is the main component of bentonite. Uranium(VI) sorption on bentonite's accessory Minerals (pyrite, calcite, mica, and feldspar) was not observed. Investigation of uranium

  8. Application of thermal barrier coating for improving the suitability of Annona biodiesel in a diesel engine

    Directory of Open Access Journals (Sweden)

    Ramalingam Senthil

    2016-01-01

    Full Text Available The Annona biodiesel was produced from Annona oil through transesterification process. The aim of the present study is to analyze the performance and emission characteristics of a single cylinder, direct injection, compression ignition engine using a annona methyl ester as a fuel. They are blended together with the Neat diesel fuel such as 20%, 40%, 60%, 80%, and Neat biodiesel. The performance, emission and combustion characteristics are evaluated by operating the engine at different loads. The performance parameters such as brake thermal efficiency, brake specific fuel consumption. The emission constituents such as carbon monoxide, unburned hydrocarbons, oxides of nitrogen, and smoke were recorded. Then the piston and both exhaust and intake valves of the test engine were coated with 100 µm of NiCrAl as lining layer. Later the same parts were coated with 400 µm material of coating that was the mixture of 88% of ZrO2, 4% of MgO, and 8% of Al2O3. After the engine coating process, the same fuels is tested in the engine at the same engine operation. The same performance and emission parameters were evaluated. Finally, these parameters are compared with uncoated engine in order to find out the changes in the performance and emission parameters of the coated engine. It is concluded that the coating engine resulting in better performance, especially in considerably lower brake specific fuel consumption values. The engine emissions are lowered both through coating and annona methyl ester biodiesel expect the nitrogen oxides emission.

  9. Sorption of tetracycline on organo-montmorillonites

    International Nuclear Information System (INIS)

    Liu, Niu; Wang, Ming-xia; Liu, Ming-ming; Liu, Fan; Weng, Liping; Koopal, Luuk K.; Tan, Wen-feng

    2012-01-01

    Highlights: ► The sorption capacity of tetracycline on Mont. modified with QACs was highly promoted. ► Tetracycline adsorbed on organoclay was affected by the amount and the length of QACs. ► Tetracycline adsorption on organoclay exhibited high pH-dependence below 5. - Abstract: Tetracycline (TC) is a veterinary antibiotic that is frequently detected as pollutant in the environment. Powerful adsorbents are required for removing TC. The present paper compares the TC adsorption capacity of Na-montmorillonite (Na-mont) with six organo-montmorillonites (organo-monts). Three quaternary ammonium cations (QACs) with different alkyl-chain lengths were used as modifiers. Powder X-ray diffraction indicated that the d 001 values of organo-monts increased with increasing the QACs loading and alkyl-chain length. The CECs of the organo-monts were substantially lower than that of Na-mont and decreased with QACs chain length and increased loading. The modeling of the adsorption kinetics revealed that the processes of TC adsorption on the tested samples could be well fitted by the pseudo-second-order equation. The maximum adsorption capacities of TC on the organo-monts (1000–2000 mmol/kg) were considerably higher than that on Na-mont (769 mmol/kg). Both the Langmuir and Freundlich model could fit the adsorption isotherms. The TC adsorption to the organo-monts increase significantly with decreasing the pH below 5.5 because of the electrostatic interaction, and a high QACs loading performed better than a low loading at around pH 3.

  10. Montmorillonite-induced Bacteriophage φ6 Disassembly

    Science.gov (United States)

    Trusiak, A.; Gottlieb, P.; Katz, A.; Alimova, A.; Steiner, J. C.; Block, K. A.

    2012-12-01

    It is estimated that there are 1031 virus particles on Earth making viruses an order of magnitude more prevalent in number than prokaryotes with the vast majority of viruses being bacteriophages. Clays are a major component of soils and aquatic sediments and can react with RNA, proteins and bacterial biofilms. The clays in soils serve as an important moderator between phage and their host bacteria, helping to preserve the evolutionary balance. Studies on the effects of clays on viral infectivity have given somewhat contradictory results; possibly a consequence of clay-virus interactions being dependent on the unique structure of particular viruses. In this work, the interaction between montmorillonite and the bacteriophage φ6 is investigated. φ6 is a member of the cystovirus family that infects Pseudomonas syringe, a common plant pathogen. As a member of the cystovirus family with an enveloped structure, φ6 serves as a model for reoviruses, a human pathogen. Experiments were conducted with φ6 suspended in dilute, purified homoionic commercial-grade montmorillonite over a range of virus:clay ratios. At a 1:100000 virus:clay ratio, the clay reduced viral infectivity by 99%. The minimum clay to virus ratio which results in a measurable reduction of P. syringae infection is 1:1. Electron microscopy demonstrates that mixed suspensions of smectite and virus co-aggregate to form flocs encompassing virions within the smectite. Both free viral particles as well as those imbedded in the flocs are seen in the micrographs to be missing the envelope- leaving only the nucleocapsid (NC) intact; indicating that smectite inactivates the virus by envelope disassembly. These results have strong implications in the evolution of both the φ6 virus and its P. syringae host cells. TEM of aggregate showing several disassembled NCs.

  11. Salinity dependence of 226Ra adsorption on montmorillonite and kaolinite

    International Nuclear Information System (INIS)

    Shuji Tamamura; Takahiro Takada; Seiya Nagao; Masayoshi Yamamoto; Keisuke Fukushi

    2014-01-01

    The effect of NaCl concentration (10.0-1,000 mM) on 226 Ra adsorption was investigated in the presence of montmorillonite and kaolinite. A positive correlation was observed between the dissolved 226 Ra and NaCl concentrations in the presence of these adsorbents. Distribution coefficients decreased from the order of 10 4 to 10 0 (mL g -1 ) with an increase in NaCl concentration. Although the coefficients were higher for montmorillonite than kaolinite at lower NaCl concentrations, the trend was reversed at higher NaCl concentrations (≥500 mM) owing to the sharper reduction of the coefficient for montmorillonite with the increase in NaCl concentration. The rapid reduction was ascribed to higher negative charge density of montmorillonite, which leads the Ra 2+ adsorption mechanism to approach charge-compensating ion exchange. (author)

  12. The evaluation of the effects of buffer thickness and dry density on radionuclides migration in engineered barrier system

    International Nuclear Information System (INIS)

    Kato, Fujitaka; Ishihara, Yoshinao; Makino, Hitoshi; Ishiguro, Katsuhiko

    2000-01-01

    The evaluation of the effects of buffer thickness and dry density, one of the buffer design, on radionuclides migration behavior is important from the viewpoint of performance assessment since they have relation to radionuclides migration retardation. It is also considered to help investigation of buffer design that satisfy both safety and economy to condition of the disposal site, which may be required with development of disposal project in the future. Therefore we have performed a sensitivity analysis used buffer thickness and dry density as parameter and considered their combination in this report. Based on this, we have evaluated the effects of buffer thickness and dry density on radionuclides migration in engineered barrier system. And, we have considered about radionuclides migration retardation quality of the buffer which is based on the design (relationship between thickness and dry density) set in the second progress report on research and development for the geological disposal of HLW in Japan. In results, the maximum release rates from the engineered barrier system for the nuclides which have high distribution coefficients and short half lives are sensitive to changes in buffer thickness and dry density. And, using dose converted from the nuclide release rates from the engineered barrier system as a convenient index, it is almost shown that the maximum of total dose is less than 10 μ Sv/y in the cases which buffer thickness and dry density are based on the buffer design set in the second progress report on research and development for the geological disposal of HLW in Japan. These can be used as an information when design of buffer thickness and dry density is set by synthetically judgement of balance of safety and economy. (author)

  13. PERFORMANCE ANALYSIS OF 1,4 DIOXANE-ETHANOL-DIESEL BLENDS ON DIESEL ENGINES WITH AND WITHOUT THERMAL BARRIER COATING

    OpenAIRE

    Chockalingam Sundar Raj; Sambandam Arul; Subramanian Sendilvelan; Ganapathy Saravanan

    2010-01-01

    1,4 dioxane, a new additive allows the splash blending of ethanol in diesel in a clear solution. The objective of this investigation is to first create a stable ethanol-diesel blended fuel with 10% 1,4 dioxane additive, and then to generate performance, combustion and emissions data for evaluation of different ethanol content on a single cylinder diesel engine with and without thermal barrier coating. Results show improved performance with blends compared to neat fuel for all conditions of th...

  14. Reference analysis on the use of engineered barriers for isolation of spent nuclear fuel in granite and basalt

    International Nuclear Information System (INIS)

    Cloninger, M.O.; Cole, C.R.

    1981-08-01

    This report evaluates the effectiveness of engineered barriers in delaying or reducing the rate of release of radionuclides from spent fuel in geologic respositories in granite and basalt. It was assumed that the major exposure pathway from the respository to humans would be the ground-water system overlying or underlying a site. Hence, this report focuses on ground-water pathways. A geosphere transport model, GETOUT, and the biosphere transport/dose models, ALLDOS and PABLM, were integrated and used to calculate the potential radiological dose that might be received by humans at various times after repository closure

  15. International conference on the performance of engineered barriers. Physical and chemical properties, behaviour and evolution. Short abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Schaefers, Annika; Fahland, Sandra (eds.)

    2014-08-01

    The volume includes the abstracts of the papers presented at the international conference on the performance of engineered barrier systems, their physical and chemical properties, behavior and evolution. The papers cover the topics bentonite buffers, radioactive waste repository safety, geophysical and geochemical property monitoring, repository sealing materials, thermo-hydro-mechanical characterization, gas injection tests, hydration and heating tests, clay-iron interaction experiments, water retention behavior, thermal stability of materials, numerical modeling studies, long-term simulations, thermo-hydrologic phenomena, uncertainty and sensitivity studies, probabilistic assessments, preliminary safety analyses of Gorleben.

  16. Implementation of geomechanical models for engineered clay barriers in multi-physic partial differential equation solvers

    International Nuclear Information System (INIS)

    Navarro, V.; Alonso, J.; Asensio, L.; Yustres, A.; Pintado, X.

    2012-01-01

    when using the mixed method. The constitutive formulation is implemented as a balance equation. This way, the user can freely implement models involving implicit relationships between variables. To illustrate the application of this method, we have analysed the implementation of a modified formulation of the Barcelona Expansive Model, a critical state model (CSM) of reference for expansive clays, as it is the case for bentonite clays for engineered barriers for radioactive nuclear spent fuel confinement. The tool developed was used to satisfactorily model the coupled hydro-mechanical problem of the free-swelling of a MX-80 bentonite disc. The bentonite sample had an initial dry density of 1600 kg/m 3 and a water content of 10% in mass. The initial dimensions of the disk were a height of 15.85 mm and a diameter of 100 mm. The hydration with deionised water applied on the top face of the sample was modelled with a saturation boundary condition. Figure 1 illustrates the case modelled and results obtained on pore water pressure and swelling of the sample at an intermediate time in the simulation. In addition, the modelling results have been compared with the experimental results obtained in the laboratory test carried out by B+TECH, as shown in Figure 2. In conclusion, the present proposal means a useful approach for the introduction of advanced Soil Mechanics models to the modelling of bentonite clays in multi-physics partial differential solvers. The use of it enables to overcome the limitations of some MPDES to integrate state functions defined implicitly. This makes it possible to combine the versatility of MPDES with powerful constitutive grounds. (authors)

  17. Influence of montmorillonite on antimicrobial activity of tetracycline and ciprofloxacin

    Science.gov (United States)

    Lv, Guocheng; Pearce, Cody W.; Gleason, Andrea; Liao, Libing; MacWilliams, Maria P.; Li, Zhaohui

    2013-11-01

    Antibiotics are used not only to fight infections and inhibit bacterial growth, but also as growth promotants in farm livestock. Farm runoff and other farm-linked waste have led to increased antibiotic levels present in the environment, the impact of which is not completely understood. Soil, more specifically clays, that the antibiotic contacts may alter its effectiveness against bacteria. In this study a swelling clay mineral montmorillonite was preloaded with antibiotics tetracycline and ciprofloxacin at varying concentrations and bioassays were conducted to examine whether the antibiotics still inhibited bacterial growth in the presence of montmorillonite. Escherichia coli was incubated with montmorillonite or antibiotic-adsorbed montmorillonite, and then the number of viable bacteria per mL was determined. The antimicrobial activity of tetracycline was affected in the presence of montmorillonite, as the growth of non-resistant bacteria was still found even when extremely high TC doses were used. Conversely, in the presence of montmorillonite, ciprofloxacin did inhibit E. coli bacterial growth at high concentrations. These results suggest that the effectiveness of antimicrobial agents in clayey soils depends on the amount of antibiotic substance present, and on the interactions between the antibiotic and the clays in the soil, as well.

  18. Re-engineering therapeutic antibodies for Alzheimer's disease as blood-brain barrier penetrating bi-specific antibodies.

    Science.gov (United States)

    Pardridge, William M

    2016-12-01

    Therapeutic antibodies are large molecule drugs that do not cross the blood-brain barrier (BBB). Therefore, drug development of therapeutic antibodies for Alzheimer's disease (AD) requires that these molecules be re-engineered to enable BBB delivery. This is possible by joining the therapeutic antibody with a transporter antibody, resulting in the engineering of a BBB-penetrating bispecific antibody (BSA). Areas covered: The manuscript covers transporter antibodies that cross the BBB via receptor-mediated transport systems on the BBB, such as the insulin receptor or transferrin receptor. Furthermore, it highlights therapeutic antibodies for AD that target the Abeta amyloid peptide, beta secretase-1, or the metabotropic glutamate receptor-1. BSAs are comprised of both the transporter antibody and the therapeutic antibody, as well as IgG constant region, which can induce immune tolerance or trigger transport via Fc receptors. Expert opinion: Multiple types of BSA molecular designs have been used to engineer BBB-penetrating BSAs, which differ in valency and spatial orientation of the transporter and therapeutic domains of the BSA. The plasma pharmacokinetics and dosing regimens of BSAs differ from that of conventional therapeutic antibodies. BBB-penetrating BSAs may be engineered in the future as new treatments of AD, as well as other neural disorders.

  19. An assessment of gas impact on geological repository. Methodology and material property of gas migration analysis in engineered barrier system

    International Nuclear Information System (INIS)

    Yamamoto, Mikihiko; Mihara, Morihiro; Ooi, Takao

    2004-01-01

    Gas production in a geological repository has potential hazard, as overpressurisation and enhanced release of radionuclides. Amongst data needed for assessment of gas impact, gas migration properties of engineered barriers, focused on clayey and cementitious material, was evaluated in this report. Gas injection experiments of saturated bentonite sand mixture, mortar and cement paste were carried out. In the experiments, gas entry phenomenon and gas outflow rate were observed for these materials. Based on the experimental results, two-phase flow parameters were evaluated quantitatively. A conventional continuum two-phase flow model, which is only practically used multidimensional multi-phase flow model, was applied to fit the experimental results. The simulation results have been in good agreement with the gas entry time and the outflow flux of gas and water observed in the experiments. It was confirmed that application of the continuum two-phase flow model to gas migration in cementitious materials provides sufficient degree of accuracy for assessment of repository performance. But, for sand bentonite mixture, further extension of basic two-phase flow model is needed especially for effect of stress field. Furthermore, gas migration property of other barrier materials, including rocks, but long-term gas injection test, clarification of influence of chemicals environment and large-scale gas injection test is needed for multi-barrier assessment tool development and their verification. (author)

  20. Field studies of engineered barriers for closure of low level radioactive waste landfills at Los Alamos, New Mexico, USA

    International Nuclear Information System (INIS)

    Nyhan, J.W.; Langhorst, G.J.; Martin, C.E.; Martinez, J.L.; Schofield, T.G.

    1993-01-01

    The Los Alamos National Laboratory examined water balance relationships for four different landfill cover designs containing engineered barriers. These field experiments were performed at Los Alamos, New Mexico, USA, in 1.0- by 10.0-m plots with downhill slopes of 5, 10, 15, and 25%. Field measurements of seepage, precipitation, interflow, runoff, and soil water content were collected in each of the 16 plots representing four slopes each with four cover designs: Conventional, EPA, Loam Capillary Barrier and Clay Loam Capillary Barrier. A seepage collection system was installed beneath each cover design to evaluate the influence of slope length on seepage using a series of four metal pans filled with medium gravel that were placed end-to-end in the bottom of each field plot. An automated water flow data logging system was used to collect hourly seepage, interflow and runoff data and consisted of 100 100-liter tanks, each of which was equipped with an ultrasonic liquid-level sensor and a motor-operated ball valve used to drain the tank. Soil water content was routinely monitored every six hours at each of 212 locations throughout the 16 plots with time domain reflectrometry (TDR) techniques using an automated and multiplexed measurement system. Field data is presented to show the effects of slope and slope length on the performance of each landfill cover design for the first 15 months of this field experiment

  1. Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells

    Science.gov (United States)

    Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

    2016-05-01

    In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm2, an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm2. Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification.

  2. Summary report of research on evaluation of coupled thermo-hydro-mechanical behavior in the engineered barrier

    International Nuclear Information System (INIS)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi; Yamashita, Ryo

    2002-02-01

    After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanisms, infiltration of groundwater from the surrounding rock in to the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltration. In order to recognize and evaluate these coupled thermo-hydro-mechanical (THM) phenomena, it is necessary to make a confidence of the mathematical models and computer codes. Evaluating these coupled THM phenomena is important in order to clarify the initial transient behavior of the EBS within the near field. DECOVALEX project is an international co-operative project for the DEvelopment of COupled models and their VALidation against EXperiments in nuclear waste isolation and it is significance to participate this project and to apply the code for the validation. Therefore, we tried to apply the developed numerical code against the subjects of DECOVALEX. In the above numerical code, swelling phenomenon is modeled as the function of water potential. However it dose no evaluate the experiment results enough. Then, we try to apply the new model. (author)

  3. Analysis on the use of engineered barriers for geologic isolation of spent fuel in a reference salt site repository

    International Nuclear Information System (INIS)

    Cloninger, M.O.; Cole, C.R.; Washburn, J.F.

    1980-12-01

    A perspective on the potential durability and effectiveness requirements for the waste form, container and other engineered barriers for geologic disposal of spent nuclear fuel has been developed. This perspective is based on calculated potential doses to individuals who may be exposed to radioactivity released from a repository via a groundwater transport pathway. These potential dose commitments were calculated with an integrated geosphere transport and bioshpere transport model. A sensitivity analysis was accomplished by varying four important system parameters, namely the waste radionuclide release rate from the repository, the delay prior to groundwater contact with the waste (leach initiation), aquifer flow velocity and flow path length. The nuclide retarding capacity of the geologic media, a major determinant of the isolation effectiveness, was not varied as a parameter but was held constant for a particular reference site. This analysis is limited to looking only at engineered barriers whose net effect is either to delay groundwater contact with the waste form or to limit the rate of release of radionuclides into the groundwater once contact has occurred. The analysis considers only leach incident scenarios, including a water well intrusion into the groundwater near a repository, but does not consider other human intrusion events or catastrophic events. The analysis has so far been applied to a reference salt site repository system and conclusions are presented.Basically, in nearly all cases, the regional geology is the most effective barrier to release of radionuclides to the biosphere; however, for long-lived isotopes of carbon, technetium and iodine, which were poorly sorbed on the geologic media, the geology is not very effective once a leach incident is initiated

  4. Evaluation of Monolithic Ceramics and Ceramic Thermal Barrier Coatings for Diesel Engine Applications

    National Research Council Canada - National Science Library

    Swab, Jeffrey J

    2001-01-01

    The Metals and Ceramics Research Branch (MCRB) of the Weapons and Materials Research Directorate is providing ceramic material characterization and evaluation to the Tank Automotive Research, Development, and Engineering Center (TARDEC...

  5. Montmorillonite stability. With special respect to KBS-3 conditions

    International Nuclear Information System (INIS)

    Karnland, Ola; Birgersson, Martin

    2006-08-01

    The basic advantageous properties, e.g. low hydraulic conductivity and high swelling pressure, of the bentonite buffer in a KBS- repository stem from a strong interaction between water and the montmorillonite mineral in the bentonite. Minerals similar in structure but with substantially lower mineral-water interaction exist in nature. Transformations from montmorillonite to such minerals are observed e.g. in burial diagenesis and in contact metamorphism. A thermodynamic consideration confirms that medium and low charged montmorillonite is not in chemical equilibrium with quartz. From a safety assessment perspective it is therefore of vital importance to quantify the montmorillonite transformation under KBS- conditions. Silica release from the montmorillonite tetrahedral layers is the initial process for several possible transformations. Replacement of silica by aluminum increases the layer charge but maintains the basic atomic structure. A sufficiently high layer charge results in an irreversible collapse of the clay-water structure, i.e. a non-swelling mineral is formed. Compared to other cations, potassium as counter ion leads to a collapse at lower layer charge and the produced phase is generally termed illite. Montmorillonite-to-illite transformation is the most frequently found alteration process in nature. Three different kinetic illitization models are reviewed and the model proposed by Huang et al. is considered the most suitable for quantification in a KBS- repository, since the kinetic rate expression and its associated parameters are systematically determined by laboratory work. The model takes into account temperature, montmorillonite fraction and potassium concentration, but do not include relevant parameters such as pH, temperature gradients and water content. Calculations by use of the Huang illitization model applied for repository conditions yield insignificant montmorillonite transformation also under very pessimistic assumptions. Other non

  6. Montmorillonite stability. With special respect to KBS-3 conditions

    Energy Technology Data Exchange (ETDEWEB)

    Karnland, Ola; Birgersson, Martin [Clay Technology AB, Lund (Sweden)

    2006-08-15

    The basic advantageous properties, e.g. low hydraulic conductivity and high swelling pressure, of the bentonite buffer in a KBS- repository stem from a strong interaction between water and the montmorillonite mineral in the bentonite. Minerals similar in structure but with substantially lower mineral-water interaction exist in nature. Transformations from montmorillonite to such minerals are observed e.g. in burial diagenesis and in contact metamorphism. A thermodynamic consideration confirms that medium and low charged montmorillonite is not in chemical equilibrium with quartz. From a safety assessment perspective it is therefore of vital importance to quantify the montmorillonite transformation under KBS- conditions. Silica release from the montmorillonite tetrahedral layers is the initial process for several possible transformations. Replacement of silica by aluminum increases the layer charge but maintains the basic atomic structure. A sufficiently high layer charge results in an irreversible collapse of the clay-water structure, i.e. a non-swelling mineral is formed. Compared to other cations, potassium as counter ion leads to a collapse at lower layer charge and the produced phase is generally termed illite. Montmorillonite-to-illite transformation is the most frequently found alteration process in nature. Three different kinetic illitization models are reviewed and the model proposed by Huang et al. is considered the most suitable for quantification in a KBS- repository, since the kinetic rate expression and its associated parameters are systematically determined by laboratory work. The model takes into account temperature, montmorillonite fraction and potassium concentration, but do not include relevant parameters such as pH, temperature gradients and water content. Calculations by use of the Huang illitization model applied for repository conditions yield insignificant montmorillonite transformation also under very pessimistic assumptions. Other non

  7. Design studies on the engineered barrier system and on the in-situ experiments under the conditions of geological environment in Horonobe

    International Nuclear Information System (INIS)

    Kurihara, Yuji; Yui, Mikazu; Tanai, Kenji

    2004-04-01

    Following studies have been done in this papers in order to apply the technologies based on H12 report to the actual geological conditions of Horonobe underground research laboratory. 1) Reconsidering the process of repository design, the design process charts of a repository were presented. In the H12 report, the design process of the engineering barrier system was followed by the facility design process. In this paper, the both processes were placed in parallel position. 2) The relation between geological conditions and the performance of engineering barrier systems and the specifications of engineering barrier systems was arranged and the geological information needed for design of engineering barrier were selected. 3) The appropriate form of geological information as input-data for design were showed and the procedure for setting input-data was presented. 4) Based on the state of geological investigations at Horonobe, mechanical input-data were arranged for the design of the in-situ experiments on engineered barrier system at HORONOBE. 5) The stability of the hall for the in-situ experiments was studied by numerical analysis and the results indicated that there are difference in stability between the depth of 500 m and 570 m. (author)

  8. Chemical buffering in natural and engineered barrier systems: Thermodynamic constraints and performance assessment consequences

    International Nuclear Information System (INIS)

    Arthur, R.C.; Wei Zhou

    2000-12-01

    Thermodynamic and kinetic constraints on the chemical buffering properties of natural and engineered-barrier systems are derived in this study from theoretical descriptions, incorporated in the reaction-path model, of reversible and irreversible mass transfer in multicomponent, multiphase systems. The buffering properties of such systems are conditional properties because they refer to a specific aqueous species in a system that is open with respect to a specific reactant. The solution to a mathematical statement of this concept requires evaluation of the dependence of the activity of the buffered species on incremental changes in the overall reaction-progress variable. This dependence can be represented by a truncated Taylor's series expansion, where the values of associated derivatives are calculated using finite-difference techniques and mass-balance, charge-balance and mass-action constraints. Kinetic constraints on buffering behavior can also be described if the relation between reactant flux and reaction rate is well defined. This relation is explicit for the important case of advective groundwater flow and water-rock interaction. We apply the theoretical basis of the chemical buffering concept to processes that could affect the performance of a deep geologic repository for nuclear waste. Specifically, we focus on the likelihood that an inverse relation must exist between the buffer intensity and the migration velocity of reaction fronts in systems involving advective or diffusive mass transport. A quantitative understanding of this relation would provide the basis for evaluating the potential role of chemical buffering in achieving the isolation and retardation functions, of the EBS and geosphere in a KBS-3 repository. Our preliminary evaluation of this role considers the effects of chemical buffering on the propagation velocity of a pH front in both the near- and far field. We use a geochemical modeling technique compatible with the reaction-path model to

  9. Chemical buffering in natural and engineered barrier systems: Thermodynamic constraints and performance assessment consequences

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, R.C.; Wei Zhou [Monitor Scientific, LLC, Denver, CO (United States)

    2000-12-01

    Thermodynamic and kinetic constraints on the chemical buffering properties of natural and engineered-barrier systems are derived in this study from theoretical descriptions, incorporated in the reaction-path model, of reversible and irreversible mass transfer in multicomponent, multiphase systems. The buffering properties of such systems are conditional properties because they refer to a specific aqueous species in a system that is open with respect to a specific reactant. The solution to a mathematical statement of this concept requires evaluation of the dependence of the activity of the buffered species on incremental changes in the overall reaction-progress variable. This dependence can be represented by a truncated Taylor's series expansion, where the values of associated derivatives are calculated using finite-difference techniques and mass-balance, charge-balance and mass-action constraints. Kinetic constraints on buffering behavior can also be described if the relation between reactant flux and reaction rate is well defined. This relation is explicit for the important case of advective groundwater flow and water-rock interaction. We apply the theoretical basis of the chemical buffering concept to processes that could affect the performance of a deep geologic repository for nuclear waste. Specifically, we focus on the likelihood that an inverse relation must exist between the buffer intensity and the migration velocity of reaction fronts in systems involving advective or diffusive mass transport. A quantitative understanding of this relation would provide the basis for evaluating the potential role of chemical buffering in achieving the isolation and retardation functions, of the EBS and geosphere in a KBS-3 repository. Our preliminary evaluation of this role considers the effects of chemical buffering on the propagation velocity of a pH front in both the near- and far field. We use a geochemical modeling technique compatible with the reaction-path model

  10. [Adsorptive Stabilization of Soil Cr (VI) Using HDTMA Modified Montmorillonite].

    Science.gov (United States)

    2016-03-15

    A series of organo-montomorillonites were prepared using Na-montomorillonite and hexadecyl trimethyl ammonium bromide (HDTMA). The organo-montomorillonites were then investigated for the remediation of Cr(VI) contaminated soils. FT-IR, XRD, SEM and N2 -BET, CEC, Zeta potential measurement were conducted to understand the structural changes of montmorillonites as different amounts of HDTMAs were added as modifier. The characterization results indicated that the clay interlayer spacing distance increased from 1. 25 nm to 2. 13 nm, the clay surface roughness decreased, the clay surface area reduced from 38.91 m² · g⁻¹ to 0.42 m² · g⁻¹, the clay exchangeable cation amount reduced from 62 cmol · kg⁻¹ to 9.9 cmol · kg⁻¹ and the clay surface charge changed from -29.1 mV to 5.59 mV as the dosage of HDTMA in montmorillonite was increased. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of Cr(VI). The effects of the initial soil Cr(VI) concentration, montmorillonites dosage, reaction time and HDTMA modification amount were investigated, respectively. The results revealed that modification of montmorillonites would manifest an attenuated physical adsorptive effect and an enhanced electrostatic adsorptive effect on Cr(VI), suggesting electrostatic effect was the major force that resulted in improved Cr(VI) adsorption onto HDTMA modified montmorillonites.

  11. Breaking the Chemical and Engineering Barriers to Lignocellulosic Biofuels: Next Generation Hydroccarbon Biorefineries

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2008-03-01

    This roadmap to “Next Generation Hydrocarbon Biorefineries” outlines a number of novel process pathways for biofuels production based on sound scientific and engineering proofs of concept demonstrated in laboratories around the world. This report was based on the workshop of the same name held June 25-26, 2007 in Washington, DC.

  12. Women's Leadership in Science, Technology, Engineering and Mathematics: Barriers to Participation

    Science.gov (United States)

    McCullough, Laura

    2011-01-01

    Despite gains overall, women are still under-represented in leadership positions in science, technology, engineering, and mathematics (STEM) fields. Data in the US suggest around one-quarter of deans and department heads are women; in science this drops to nearly 1 in 20. Part of this problem of under-representation stems from the population pool:…

  13. Safety evaluation methodology of engineering barriers at repository for low and intermediate level radioactive waste

    International Nuclear Information System (INIS)

    Zarnic, R.; Bokan Bosiljkov, V.; Giacomelli, M.

    2007-01-01

    Analyses of the roles of cement-based barriers in radioactive waste isolation show that models used to estimate their characteristics during the lifetime of the repository must consider the alteration of material properties with time due to degradation processes. Reinforced concrete barriers at repositories shall be designed in such manner that they fulfil besides isolative capabilities also the required functions of mechanical resistance and stability. Key elements of safety evaluation are mainly the correct selection of materials for mineral composites with cement binder (cements, aggregates, mineral additives and chemical admixtures) and their design, execution of construction works and production of precast concrete containers (continuous casting of concrete - no cold joints, limited number of construction joints, proper placing and consolidation, finishing and curing), strict control of used materials and inspection of works, as well as investigation after the construction (visual inspection, non-destructive testing, monitoring, ageing assessment on test containers). According to the methodology presented in this paper the lifetime of the repository can be estimated and, if shorter than 300 years or shorter than the period resulting from safety analysis, appropriate corrective measures shall be taken. (author)

  14. Polymerization of alanine in the presence of a non-swelling montmorillonite

    Science.gov (United States)

    Paecht-Horowitz, M.; Lahav, N.

    1977-01-01

    Alanine, starting from alanine-adenylate, has been polymerized in the presence of non-swelling Al-montmorillonite. The yield of polymerization is much lower than that obtained in the presence of swelling Na-montmorillonite. The possibility that the changing interlayer spacing in Na-montmorillonite might be responsible for its catalytic properties, is discussed.

  15. Identifying barriers to Science, Technology, Society and environment (STSE) educational goals and pedagogy in science education: A case study of UMASS Lowell undergraduate engineering

    Science.gov (United States)

    Phaneuf, Tiffany

    The implementation of sustainable development in higher education is a global trend. Engineers, as gatekeepers of technological innovation, confront increasingly complex world issues ranging from economic and social to political and environmental. Recently, a multitude of government reports have argued that solving such complex problems requires changes in the pedagogy of engineering education, such as that prescribed by the Science, Technology, Society, and education (STS) movement that grew out of the environmental movement in the 70s. In STS students are engaged in the community by understanding that scientific progress is innately a sociopolitical process that involves dimensions of power, wealth and responsibility. United States accreditation criteria now demand "the broad education necessary to understand the impact of engineering solutions in a global, economic, environmental, and societal context" (ABET Engineering Accreditation Commission 2005). With such emphasis on STS education as necessary to address complex world issues, it is vital to assess the barriers in the traditional engineering curriculum that may inhibit the success of such educational reform. This study identifies barriers to STS goals and pedagogy in post secondary science education by using the Francis College of Engineering at UMASS Lowell as a single case study. The study draws on existing literature to develop a theoretical framework for assessing four hypothesized barriers to STS education in undergraduate engineering. Identification of barriers to STS education in engineering generates a critical reflection of post secondary science education and its role in preparing engineers to be active citizens in shaping a rapidly globalizing world. The study offers policy recommendations for enabling post secondary science education to incorporate STS education into its curriculum.

  16. Field tests on migration of TRU-nuclide, (2). Migration test for engineered barrier materials in aerated soil

    International Nuclear Information System (INIS)

    Maeda, Toshikatsu; Tanaka, Tadao; Mukai, Masayuki

    2003-01-01

    Field tests on migration of radionuclides for engineered barrier materials such as bentonite and cementitious materials were performed. The tests were run under both wet conditions with artificial rainfall and dry conditions with natural rainfall. Laboratory experiments such as batch adsorption tests were also conducted to analyze the result of field test. The results of field tests agreed with the predicted moisture conditions and the migration behaviors observed at the laboratory experiment that is reported so far. For bentonite material, the movements of the tracer were calculated using known information such as the results of batch sorption tests and migration mechanism. Comparing the result of field test and calculations, it is suggested that tracer migration behavior in bentonite material in field can be evaluated quantitatively by the known migration mechanism and the results of laboratory experiments such as batch sorption test. (author)

  17. Contribution on the study of microbial effects on the leaching of radionuclides embedded in nuclear waste engineered barriers

    International Nuclear Information System (INIS)

    Spor, H.

    1994-05-01

    The aim of this work is to study the different interactions mechanisms between microorganisms and radioelements in conditions similar to those of a radioactive waste disposal site and to determine all the mechanisms due to microbial effects on the leaching of radionuclides embedded in nuclear waste engineered barriers. In this work are presented the different following points: - a bibliographic study on the microorganisms-radioelements interactions; - the conditions of metabolites production during the microbial growth (influence of the nature of the carbonated source, pH effects, aerobiosis conditions...); the mechanisms of a direct effect for determining the importance of the bio-sorption mechanism by microorganisms; the fact that the microbial biomass can strongly interact with actinides, heavy metals and radioelements; the effects of microorganisms on storage materials (cement and clay) containing radioelements (uranium, cesium); the complexation capacities of the organic and mineral acids produced during the microbial growth. (O.M.)

  18. Summary of activities at the Engineered Barriers Test Facility, October 1, 1995 to January 31, 1997, and initial data

    International Nuclear Information System (INIS)

    Porro, I.; Keck, K.N.

    1997-03-01

    Replicates of two engineered barrier designs (a thick soil barrier and a bio/capillary barrier) were constructed in the test plots of the facility. Prior to placement of any soil in the test plots, instruments were calibrated and attached to plot instrument towers, which were then installed in the test plots. Soil from Spreading Area B was installed in the test plots in lifts and compacted. Instruments attached to the instrument tower were placed in shallow trenches dug in the lifts and buried. Each instrument was checked to make sure it functioned prior to installation of the next lift. Soil samples were collected from each lift in one plot during construction for later determination of physical and hydraulic properties. After completion of the test plots, the data acquisition system was finalized, and data collection began. Appropriate instrument calibration equations and equation coefficients are presented, and data reduction techniques are described. Initial data show test plot soils drying throughout the summer and early fall. This corresponds to low rainfall during this period. Infiltration of water into the test plots was first detected around mid-November with several subsequent episodes in December. Infiltration was verified by corresponding measurements from several different instruments ime domain reflectometry (TDR), neutron probe, thermocouple psychrometers, and heat dissipation sensors Tensiometer data does not appear to corroborate data from the other instruments. Test plots were warmer on the side closest to the access trench indicating a temperature effect from the trench. This resulted in greater soil moisture freezing with less and shallower infiltration on the far side of the plots than on the side closest to the trench. At the end of this monitoring period, infiltration in all but two of the test plots has reached the 155-cm depth. Infiltration in test plots B2 and S3 has reached only the 140-cm depth. The monitored infiltration events have not

  19. Dissolution characteristics of chalcedony under alkaline condition. Study for changes in mineral composition of engineered barrier composed by bentonite

    International Nuclear Information System (INIS)

    Watanabe, Yasutaka; Yokoyama, Shingo

    2016-01-01

    In the engineered barrier of radioactive waste disposal facilities, it is expected that bentonite is exposed to alkaline groundwater which arise from leaching of cementations materials. Minerals contained in the bentonite will be dissolved by reactions of the alkaline groundwater. Some bentonite contains silica such as quartz and chalcedony. Chalcedony is categorized in intermediate silica which is microcrystalline. It is known that dissolution of silica influences to the dissolution of smectite by means of solubility. However, dissolution kinetics of chalcedony in the alkaline condition has not been investigated, which is an uncertainty in geochemical simulations to evaluate a long-term stability of the engineered barrier. Therefore, this study performed flow-through experiments in alkaline conditions using chalcedony in order to obtain the dissolution rate of the chalcedony. The flow-through experiments was performed using NaOH-NaCl solution adjusted to 0.3 mol/L of ionic strength. Initial pH of the solution was from 8.9 to 13.5. As a result, higher pH and higher temperature showed higher Si ion concentrations of reacted solutions. The dissolution rate of the samples was calculated using Si ion concentrations at steady state of the experiment. Note that, the dissolution rate of the chalcedony was almost same as that of quartz at same temperature. After the experiments, SEM observation showed that rough surface of the chalcedony partly changed to smooth surface like quartz. It is supposed that rough surface of chalcedony was rapidly dissolved because of low degree of crystallization. The dissolution rate obtained is supposedly applicable to highly crystalline SiO 2 of chalcedony. (author)

  20. Low-voltage high-speed programming gate-all-around floating gate memory cell with tunnel barrier engineering

    Science.gov (United States)

    Hamzah, Afiq; Ezaila Alias, N.; Ismail, Razali

    2018-06-01

    The aim of this study is to investigate the memory performances of gate-all-around floating gate (GAA-FG) memory cell implementing engineered tunnel barrier concept of variable oxide thickness (VARIOT) of low-k/high-k for several high-k (i.e., Si3N4, Al2O3, HfO2, and ZrO2) with low-k SiO2 using three-dimensional (3D) simulator Silvaco ATLAS. The simulation work is conducted by initially determining the optimized thickness of low-k/high-k barrier-stacked and extracting their Fowler–Nordheim (FN) coefficients. Based on the optimized parameters the device performances of GAA-FG for fast program operation and data retention are assessed using benchmark set by 6 and 8 nm SiO2 tunnel layer respectively. The programming speed has been improved and wide memory window with 30% increment from conventional SiO2 has been obtained using SiO2/Al2O3 tunnel layer due to its thin low-k dielectric thickness. Furthermore, given its high band edges only 1% of charge-loss is expected after 10 years of ‑3.6/3.6 V gate stress.

  1. Barriers to the Uptake of Concurrent Engineering in the Nigerian Construction Industry

    OpenAIRE

    Aniekwu, Nathaniel Anny; Igboanugo, Anthony C.

    2012-01-01

    It is the consensus of scholars that the productivity of the construction industry is very low when compared with other industries. Concurrent Engineering (CE), which has a primary goal of reducing the total time from designing a product to releasing it into the market, while creating better designs as well, has been identified as one of the concepts that has yielded effective adaptation in the construction industry. An exploratory survey was used to identify 63 variables with the capacity to...

  2. Biodegradation of bacterial polysaccharides adsorbed on montmorillonite

    International Nuclear Information System (INIS)

    Guckert, A.; Tok, H.H.; Jacquin, F.

    1977-01-01

    In this research, by means of a model, a study was made of the biodegradation of microbial organic compounds adsorbed on clays, with a parallel experiment on Fontainebleau sand serving as the control. During incubation the three classes of organic matter ( 14 C-labelled glucose, 14 C-labelled polysaccharides and 14 C-labelled microbial cells) mineralize more actively in the presence of sand than in the presence of clay, since the latter provides protection against biodegradation. Mineralization of the adsorbed organic compounds, however, is marked by clear-cut differences after three weeks - glucose (55%)>polysaccharides (43%)>microbial organisms (7.3%). After incubation, chemical extraction of the organo-mineral complexes by alkaline solvents shows only water-soluble and alkali-soluble products in the case of sand; conversely, in that of montmorillonite the bulk of the 14 C was found in the non-extractable fraction or humin (18.1% of the initial 14 C for glucose, 27.3% for the polysaccharides, and 67.6% for the microbial organisms). A second incubation carried out after a phase in which there was drying and remoistening of the organo-mineral complexes, brings to light the important part played by climatic alternations during the biodegradation process. A new mineralization phase is observed, affecting more the bacterial organisms (14.1%) than the polysaccharides (6.3%), with the glucose-base complexes occupying an intermediate position (11.2%). The chemical fractioning of the organo-mineral complexes following re-incubation shows the stability of 14 C in humin very clearly, especially in the case of polysaccharides, where the mineralization phase relates primarily to the products extractable with alkalis. (author)

  3. Modified montmorillonite as vector for gene delivery.

    Science.gov (United States)

    Lin, Feng-Huei; Chen, Chia-Hao; Cheng, Winston T K; Kuo, Tzang-Fu

    2006-06-01

    Currently, gene delivery systems can be divided into two parts: viral or non-viral vectors. In general, viral vectors have a higher efficiency on gene delivery. However, they may sometimes provoke mutagenesis and carcinogenesis once re-activating in human body. Lots of non-viral vectors have been developed that tried to solve the problems happened on viral vectors. Unfortunately, most of non-viral vectors showed relatively lower transfection rate. The aim of this study is to develop a non-viral vector for gene delivery system. Montmorillonite (MMT) is one of clay minerals that consist of hydrated aluminum with Si-O tetrahedrons on the bottom of the layer and Al-O(OH)2 octahedrons on the top. The inter-layer space is about 12 A. The room is not enough to accommodate DNA for gene delivery. In the study, the cationic hexadecyltrimethylammonium (HDTMA) will be intercalated into the interlayer of MMT as a layer expander to expand the layer space for DNA accommodation. The optimal condition for the preparation of DNA-HDTMA-MMT is as follows: 1 mg of 1.5CEC HDTMA-MMT was prepared under pH value of 10.7 and with soaking time for 2 h. The DNA molecules can be protected from nuclease degradation, which can be proven by the electrophoresis analysis. DNA was successfully transfected into the nucleus of human dermal fibroblast and expressed enhanced green fluorescent protein (EGFP) gene with green fluorescence emission. The HDTMA-MMT has a great potential as a vector for gene delivery in the future.

  4. Field plate engineering for GaN-based Schottky barrier diodes

    International Nuclear Information System (INIS)

    Lei Yong; Shi Hongbiao; Lu Hai; Chen Dunjun; Zhang Rong; Zheng Youdou

    2013-01-01

    The practical design of GaN-based Schottky barrier diodes (SBDs) incorporating a field plate (FP) structure necessitates an understanding of their working mechanism and optimization criteria. In this work, the influences of the parameters of FPs upon breakdown of the diode are investigated in detail and the design rules of FP structures for GaN-based SBDs are presented for a wide scale of material and device parameters. By comparing three representative dielectric materials (SiO 2 , Si 3 N 4 and Al 2 O 3 ) selected for fabricating FPs, it is found that the product of dielectric permittivity and critical field strength of a dielectric material could be used as an index to predict its potential performance for FP applications. (semiconductor devices)

  5. Feasibility of using a high-level waste canister as an engineered barrier in disposal

    International Nuclear Information System (INIS)

    Slate, S.C.; Pitman, S.G.; Nesbitt, J.F.; Partain, W.L.

    1982-08-01

    The objective of this report is to evaluate the feasibility of designing a process canister that could also serve as a barrier canister. To do this a general set of performance criteria is assumed and several metal alloys having a high probability of demonstrating high corrosion resistance under repository conditions are evaluated in a qualitative design assessment. This assessment encompasses canister manufacture, the glass-filling process, interim storage, transportation, and to a limited extent, disposal in a repository. A series of scoping tests were carried out on two titanium alloys and Inconel 625 to determine if the high temperature inherent in the glass-fill processing would seriously affect either the strength or corrosion resistance of these metals. This is a process-related concern unique to the barrier canister concept. The material properties were affected by the heat treatments which simulated both the joule-heated glass melter process (titanium alloys and Inconel 625) and the in-can melter (ICM) process (Inconel 625). However, changes in the material properties were generally within 20% of the original specimens. Accelerated corrosion testing of the heat treated coupons in a highly oxygenated brine showed basic corrosion resistance of titanium grade 12 and Inconel 625 to compare favorably with that of the untreated coupons. The titanium grade 2 coupons experienced severe corrosion pitting. These corrosion tests were of a scoping nature and suitable primarily for the detection of gross sensitivity to the heat treatment inherent in the glass-fill process. They are only suggstive of repository performance since the tests do not adequately model the wide range of repository conditions that could conceivably occur

  6. Preparation and characterization of exfoliated polyaniline/montmorillonite nanocomposites

    International Nuclear Information System (INIS)

    Narayanan, Binitha N.; Koodathil, Ranjana; Gangadharan, Tripti; Yaakob, Zahira; Saidu, Femina K.; Chandralayam, Soumini

    2010-01-01

    Transition metal ions were exchanged with the interlamellar cations of montmorillonite clays and polymerization of aniline was done within the layers. The delaminated clay layers upon ion exchange resulted in exfoliated polyaniline/clay nanocomposite formation which has profound effects on polymer structure, properties and electrical conduction mechanisms. Here we offer polyaniline (PANI)/montmorillonite exfoliated nanocomposite synthesized through a simple, cheap route which need not require complicated and less economical organophilic modification. The prepared composites were characterized using XRD, FTIR, and TG/DTA to prove exfoliation.

  7. Preparation and characterization of exfoliated polyaniline/montmorillonite nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Narayanan, Binitha N., E-mail: binithann@yahoo.co.i [Department of Chemistry, Sree Neelakanta Government Sanskrit College, Pattambi, Palakkad 679306, Kerala (India); Department of Chemical and Process Engineering, Faculty of Engineering, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Koodathil, Ranjana; Gangadharan, Tripti [Department of Chemistry, Sree Neelakanta Government Sanskrit College, Pattambi, Palakkad 679306, Kerala (India); Yaakob, Zahira [Department of Chemical and Process Engineering, Faculty of Engineering, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Saidu, Femina K.; Chandralayam, Soumini [Department of Chemistry, Sree Neelakanta Government Sanskrit College, Pattambi, Palakkad 679306, Kerala (India)

    2010-04-15

    Transition metal ions were exchanged with the interlamellar cations of montmorillonite clays and polymerization of aniline was done within the layers. The delaminated clay layers upon ion exchange resulted in exfoliated polyaniline/clay nanocomposite formation which has profound effects on polymer structure, properties and electrical conduction mechanisms. Here we offer polyaniline (PANI)/montmorillonite exfoliated nanocomposite synthesized through a simple, cheap route which need not require complicated and less economical organophilic modification. The prepared composites were characterized using XRD, FTIR, and TG/DTA to prove exfoliation.

  8. Full-scale test on coupled thermo-hydro-mechanical processes in engineered barrier system

    International Nuclear Information System (INIS)

    Moro, Yoshiji; Fujita, Tomoo; Kanno, Takeshi; Kobayashi, Akira.

    1994-01-01

    On dynamic behavior within artificial barrier in ground layer disposal of high level radioactive wastes, some phenomena such as exotherm from the wastes, penetration of groundwater from surrounding base rock, swelling pressure formation of buffer material due to penetration of groundwater, ground pressure change of the surrounding base rock, and so forth are supposed to affect each other. It is one of important problems from a viewpoint of elucidation of near field environment in the property evaluation study to evaluate such thermo-hydro-mechanical coupled phenomena. As results of the investigation from such reason and its application to actual test in accompany with execution of heating and water inserting test in the Big-Ben (Big-Bentonite facility), the following informations were obtained: (1) In heating and water inserting test, data on temperature distribution, water content ratio distribution and swelling pressure of each portion for 5 months could be obtained. (2) water migration due to water slope was divided to migrations due to steam and liquid water, of which models were made according to Fick and Darcy laws, respectively. (3) As a simulation of water migration, water diffusion coefficient due to temperature slope could be expressed almost by a model with nonlinearity to temperature. (G.K.)

  9. A qualitative, interprofessional analysis of barriers to and facilitators of implementation of the Department of Veterans Affairs' Clostridium difficile prevention bundle using a human factors engineering approach.

    Science.gov (United States)

    Yanke, Eric; Moriarty, Helene; Carayon, Pascale; Safdar, Nasia

    2018-03-01

    Clostridium difficile infection (CDI) is increasingly prevalent, severe, and costly. Adherence to infection prevention practices remains suboptimal. More effective strategies to implement guidelines and evidence are needed. Interprofessional focus groups consisting of physicians, resident physicians, nurses, and health technicians were conducted for a quality improvement project evaluating adherence to the Department of Veterans Affairs' (VA) nationally mandated C difficile prevention bundle. Qualitative analysis with a visual matrix display identified barrier and facilitator themes guided by the Systems Engineering Initiative for Patient Safety model, a human factors engineering approach. Several themes, encompassing both barriers and facilitators to bundle adherence, emerged. Rapid turnaround time of C difficile polymerase chain reaction testing was a facilitator of timely diagnosis. Too few, poorly located, and cluttered sinks were barriers to appropriate hand hygiene. Patient care workload and the time-consuming process of contact isolation precautions were also barriers to adherence. Multiple work system components serve as barriers to and facilitators of adherence to the VA CDI prevention bundle among an interprofessional group of health care workers. Organizational factors appear to significantly influence bundle adherence. Interprofessional perspectives are needed to identify barriers to and facilitators of bundle implementation, which is a necessary first step to address adherence to bundled infection prevention practices. Published by Elsevier Inc.

  10. Interface Schottky barrier engineering via strain in metal-semiconductor composites

    Science.gov (United States)

    Ma, Xiangchao; Dai, Ying; Yu, Lin; Huang, Baibiao

    2016-01-01

    The interfacial carrier transfer property, which is dominated by the interface Schottky barrier height (SBH), plays a crucial role in determining the performance of metal-semiconductor heterostructures in a variety of applications. Therefore, artificially controlling the interface SBH is of great importance for their industrial applications. As a model system, the Au/TiO2 (001) heterostructure is studied using first-principles calculations and the tight-binding method in the present study. Our investigation demonstrates that strain can be an effective way to decrease the interface SBH and that the n-type SBH can be more effectively decreased than the p-type SBH. Astonishingly, strain affects the interface SBH mainly by changing the intrinsic properties of Au and TiO2, whereas the interfacial potential alignment is almost independent of strain due to two opposite effects, which are induced by strain at the interfacial region. These observed trends can be understood on the basis of the general free-electron gas model of typical metals, the tight-binding theory and the crystal-field theory, which suggest that similar trends may be generalized for many other metal-semiconductor heterostructures. Given the commonness and tunability of strain in typical heterostructures, we anticipate that the tunability of the interface SBH with strain described here can provide an alternative effective way for realizing more efficient applications of relevant heterostructures.The interfacial carrier transfer property, which is dominated by the interface Schottky barrier height (SBH), plays a crucial role in determining the performance of metal-semiconductor heterostructures in a variety of applications. Therefore, artificially controlling the interface SBH is of great importance for their industrial applications. As a model system, the Au/TiO2 (001) heterostructure is studied using first-principles calculations and the tight-binding method in the present study. Our investigation

  11. Corrosion of high purity copper as engineering barrier in deep geological repositories

    International Nuclear Information System (INIS)

    Ochoa, Maité; Rodríguez Martín, A.; Farina Silvia, B.

    2013-01-01

    Pure copper with oxygen content below 5 ppm (to minimize segregation at grain boundaries) and doped with phosphorus (to increase creep resistance) is the chosen material for the corrosion-resistant barrier of the High Level Radioactive 2 Wastecontainers in the Swedish and Finnish repository models. These models include the construction of the repository below the water table, which is a reducing environment in which copper has excellent resistance to general and localized corrosion in aqueous electrolytes. The aim of this work is contribute to determine the durability of the material, given that deep geological repositories of HLW are designed to ensure the protection of the environment for periods of hundreds of thousands years. As a first step in a more general analysis the effects of chloride, one of the main aggressive species of corrosion, are evaluated. To this purpose corrosion potential was determined and anodic polarization curves were performed in deaerated solutions varying the chloride concentration between 0.01 and 1M and the temperature between 30 and 90°C. Several electrochemical techniques were used: the evolution of corrosion potential was measured, anodic polarization curves were obtained and electrochemical impedance tests were performed. The analysis was complemented with microscopic observations of the type of corrosive attack, as well as determinations of the eventual corrosion products formed using Energy-Dispersive X-ray Analysis (EDS). Results show that the corrosion potential decreases with the increase of temperature and with the increase of chloride concentration. A correlation of the corrosion potential as a function of temperature and chloride concentration was obtained, with the purpose of making predictions in variable conditions.The current density increases both with temperature and with chloride concentration. A pitting potential is observed in certain conditions. (author)

  12. Synthesis of poly(furfuryl alcohol)/montmorillonite nanocomposites ...

    Indian Academy of Sciences (India)

    The purpose of this study was to obtain poly(furfuryl alcohol) nanocomposites with Algerian organically modified clay (termed 12-montmorillonite). The formation of poly(furfuryl alcohol) was confirmed by infrared spectroscopy (IR); the prepared nanocomposites were characterized by X-ray diffraction (XRD), transmission ...

  13. Hybrid structures based on montmorillonite/modified starch intercalate

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena

    2010-01-01

    Roč. 104, č. 9 (2010), s. 885 ISSN 0009-2770. [International Conference on Polysaccharides-Glycoscience /6./. 29.09.2010-1.10.2010, Praha] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505 Keywords : organic/inorganic hybrides * montmorillonite Subject RIV: JI - Composite Materials

  14. Effect of montmorillonite on arsenic accumulation in common carp

    African Journals Online (AJOL)

    Yomi

    2012-02-01

    Feb 1, 2012 ... The effect of montmorillonite (MMT) on dietary arsenic (As(III)) accumulation in tissues of common carp ..... by clay minerals has been primarily attributed to the .... Trace elements (Cu or Zn) concentration in sampled tissues of common carp after .... interactions among mixtures of lead, cadmium and arsenic.

  15. Adsorption of copper ions of natural montmorillonite clay

    Directory of Open Access Journals (Sweden)

    Pimneva Ludmila

    2017-01-01

    Full Text Available The prospects of montmorillonite clay using for the extraction of copper ions from natural and waste waters were determined. Specified chemical and phase composition of natural forms of the montmorillonite clay are shown in the article. Quantitative characteristics of adsorption process of copper ions, the statistical exchange capacity is 1,21 (298 К, 1,25 (313 К, 1,43 (333 К. The authors have studied the balance of copper ions by the method of constructing the isotherms. The description of the adsorption process was carried out by the Langmuir, Freundlich and Temkin models. The calculations showed that the best data for the sorption described by Langmuir model. The nature of the interaction of copper ions with montmorillonite clay in natural form is presented. The calculated thermodynamic parameters of the adsorption process, the obtained values of the Gibbs energy have a negative sign -11,5 (298 К, -15,6 (313 К, -16,2 (333 К кJ/mol, that corresponds to a sustainable consolidation of copper ions on the surface of the montmorillonite clay.

  16. Different level of fluorescence in Raman spectra of montmorillonites

    Czech Academy of Sciences Publication Activity Database

    Ritz, M.; Vaculíková, Lenka; Kupková, J.; Plevová, Eva; Bartoňová, L.

    2016-01-01

    Roč. 84, May 2016 (2016), s. 7-15 ISSN 0924-2031 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : Raman spectroscopy * fluorescence * montmorillonite Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.740, year: 2016

  17. Homoionic inorganic montmorillonites as fillers for Polyamide 6 nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Kadlecová, Z.; Puffr, Rudolf; Baldrian, Josef; Schmidt, Pavel; Roda, J.; Brožek, J.

    2008-01-01

    Roč. 44, č. 9 (2008), s. 2798-2806 ISSN 0014-3057 Institutional research plan: CEZ:AV0Z40500505 Keywords : poly(.epsilon.-caprolactam) nanocomposite * calcium and magnesium montmorillonites * WAX analysis Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.143, year: 2008

  18. Characterization and Identification of Bituminous Materials Modified with Montmorillonite Nanoclay

    NARCIS (Netherlands)

    Liu, G.

    2011-01-01

    Montmorillonite (Mt) nanoclay is a layered silicate mineral with a 2:1-type layer structure, two tetrahedrals sandwiching one octahedral. In recent decades, it is successfully introduced into polymer systems to form polymer-clay nanocomposites (PCN) in which the silicate layers of the Mt are

  19. Improvement in tensile properties of PVC–montmorillonite ...

    Indian Academy of Sciences (India)

    mechanical properties of PVC–montmorillonite materials are also currently of huge ... Its hard form can withstand a tensile stress in the order of 46–52 MPa before .... 2θ at 25 mA and 40 kV using Cu-Kα radiation. X-ray diffraction patterns of the ...

  20. Processing and properties of polyethylene/montmorillonite nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Měřínská, D.; Kubisova, H.; Kalendová, A.; Svoboda, P.; Hromádková, Jiřina

    2012-01-01

    Roč. 25, č. 1 (2012), s. 115-131 ISSN 0892-7057 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer nanocomposite * montmorillonite * polyethylene Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.750, year: 2012

  1. Integrated programme of research into the behaviour of the clay engineered barrier: an example from Nagra's Grimsel test site

    International Nuclear Information System (INIS)

    Biggin, C.; Alexander, R.; Kickmaier, W.; McKinley, I.G.

    2003-01-01

    Many designs for the disposal of higher activity radioactive wastes include bentonite clay as part of the engineered barrier system (EBS). Generally, the EBS is characterised by the use of large quantities of rather simple, well-understood materials, leading to increased confidence in the predicted long-term behaviour of the EBS (see, for example, Alexander and McKinley, 1999). Despite this, several open questions remain and some of these are being examined at Nagra's Grimsel Test Site (GTS) in the central Swiss Alps as part of an integrated, international study programme (GTS Phase V: see www.grimsel.com for details). Three specific projects within GTS Phase V are currently investigating the performance assessment (PA) implications of the behaviour of bentonite in the EBS. In the first, demonstration of the overall practicability of the Spanish reference disposal concept (where canisters are placed horizontally in bentonite backfilled tunnels) for high level waste (HLW) is amongst the goals of ENRESA's Full-scale Engineered Barrier EXperiment (FEBEX). In the second, RWMC are examining the potential effects of gas migration through a bentonite-sand mixture surrounding a concrete silo in the Japanese concept for intermediate level waste (ILW) in a large-scale EBS experiment (GMT, Gas Migration Test). Finally, Nagra, in the CRR (Colloid and Radionuclide Retardation) project, is investigating the effects of bentonite colloids on migration of radionuclides at the EBS / geosphere boundary, where bentonite colloids could be produced by erosion of the bentonite backfill. Although all three projects have produced significant advances in the understanding of the behaviour of the clay EBS under in situ conditions, they are based on first generation conceptual designs and so, in the planned Phase VI of the GTS, it is proposed to move on and consider more optimised EBS designs and emplacement techniques. To facilitate integration, the focus of Phase VI will be narrowed to

  2. Modeling of irradiated graphite {sup 14}C transfer through engineered barriers of a generic geological repository in crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Poskas, Povilas; Grigaliuniene, Dalia, E-mail: Dalia.Grigaliuniene@lei.lt; Narkuniene, Asta; Kilda, Raimondas; Justinavicius, Darius

    2016-11-01

    There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of {sup 14}C. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the {sup 14}C transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released {sup 14}C into organic and inorganic compounds as well as the most recent information on {sup 14}C source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic {sup 14}C into the geosphere can vary from 10{sup −} {sup 11} y{sup −} {sup 1} (for non-encapsulated graphite) to 10{sup −} {sup 12} y{sup −} {sup 1} (for encapsulated graphite) while of organic {sup 14}C it was about 10{sup −} {sup 3} y{sup −} {sup 1} of its inventory. Such difference demonstrates that investigations on the {sup 14}C inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic {sup 14}C transfer was the sorption coefficient in the backfill and for organic {sup 14}C transfer – the backfill hydraulic conductivity. - Highlights: • Graphite moderated nuclear reactors are being decommissioned. • We studied interaction of disposed material with surrounding environment. • Specifically {sup 14}C transfer through engineered barriers of a geological repository. • Organic {sup 14}C flux to geosphere is considerably higher than inorganic

  3. Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

    International Nuclear Information System (INIS)

    Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

    2016-01-01

    Highlights: • Composite membranes are prepared with different montmorillonites and nafion solution. • Proton conductivities of the composite membranes are between 36.0 mS/cm and 38.5 mS/cm. • Ethanol permeability is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s. • Water uptake is approximately 24.30 mass%. - Abstract: The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s.

  4. Intended long term performances of cementitious engineered barriers for future storage and disposal facilities for radioactive wastes in Romania

    Directory of Open Access Journals (Sweden)

    Sociu F.

    2013-07-01

    Full Text Available Considering the EU statements, Romania is engaged to endorse in the near future the IAEA relevant publications on geological repository (CNCANa, to update the Medium and Long Term National Strategy for Safe Management of Radioactive Waste and to approve the Road Map for Geological Repository Development. Currently, for example, spent fuel is wet stored for 6 years and after this period it is transported to dry storage in MACSTOR-200 (a concrete monolithic module where it is intended to remain at least 50 years. The present situation for radioactive waste management in Romania is reviewed in the present paper. Focus will be done on existent disposal facilities but, also, on future facilities planned for storage / disposal of radioactive wastes. Considering specific data for Romanian radioactive waste inventory, authors are reviewing the advance in the radioactive waste management in Romania considering its particularities. The team tries to highlight the expected limitations and unknown data related with cementitious engineered barriers that has to be faced in the near future incase of interim storage or for the upcoming long periods of disposal.

  5. A consistent approach for the development of a comprehensive data base of time-dependent parameters for concrete engineered barriers

    Energy Technology Data Exchange (ETDEWEB)

    Seetharam, Suresh C; Perko, Janez; Jacques, Diederik [Belgian Nuclear Research Centre SCK-CEN, Mol (Belgium); Mallants, Dirk [CSIRO Land and Water, Urrbrae (Australia)

    2013-07-01

    This paper presents a consistent approach for the development of a comprehensive data base of time-dependent hydraulic and transport parameters for concrete engineered barriers of the future Dessel near surface repository for low level waste. The parameter derivation is based on integration of selected data obtained through an extensive literature review, data from experimental studies on cementitious materials specific for the Dessel repository and numerical modelling using physically-based models of water and mass transport. Best estimate parameter values for assessment calculations are derived, together with source and expert range and their probability density function wherever the data was sufficient. We further discuss a numerical method for up-scaling laboratory derived parameter values to the repository scale; the resulting large-scale effective parameters are commensurate with numerical grids used in models for radionuclide migration. To accommodate different levels of conservatism in the various assessment calculations defined by ONDRAF/NIRAS, several sets of parameter values have been derived based on assumptions that introduce different degrees of conservatism. For pertinent parameters, the time evolution of such properties due to the long-term concrete degradation is also addressed. The implementation of the consistent approach is demonstrated by considering the pore water diffusion coefficient as an example. (authors)

  6. Influence of Cracks in Cementitious Engineered Barriers in a Near-Surface Disposal System: Assessment Analysis of the Belgian Case

    International Nuclear Information System (INIS)

    Perko, Janez; Seetharam, Suresh C.; Jacques, Diederik; Mallants, Dirk; Cool, Wim; Vermarien, Elise

    2013-01-01

    In large cement-based structures such as a near surface disposal facility for radioactive waste voids and cracks are inevitable. However, the pattern and nature of cracks are very difficult to predict reliably. Cracks facilitate preferential water flow through the facility because their saturated hydraulic conductivity is generally higher than the conductivity of the cementitious matrix. Moreover, sorption within the crack is expected to be lower than in the matrix and hence cracks in engineered barriers can act as a bypass for radionuclides. Consequently, understanding the effects of crack characteristics on contaminant fluxes from the facility is of utmost importance in a safety assessment. In this paper we numerically studied radionuclide leaching from a crack-containing cementitious containment system. First, the effect of cracks on radionuclide fluxes is assessed for a single repository component which contains a radionuclide source (i.e. conditioned radwaste). These analyses reveal the influence of cracks on radionuclide release from the source. The second set of calculations deals with the safety assessment results for the planned near-surface disposal facility for low-level radioactive waste in Dessel (Belgium); our focus is on the analysis of total system behaviour in regards to release of radionuclide fluxes from the facility. Simulation results are interpreted through a complementary safety indicator (radiotoxicity flux). We discuss the possible consequences from different scenarios of cracks and voids. (authors)

  7. Corrosion of similar and dissimilar metal crevices in the engineered barrier system of a potential nuclear waste repository

    International Nuclear Information System (INIS)

    He, X.; Dunn, D.S.; Csontos, A.A.

    2007-01-01

    Crevice corrosion is considered possible if the corrosion potential (E corr ) exceeds the repassivation potential for crevice corrosion (E rcrev ). In this study, potentiodynamic polarization and potentiostatic hold were used to determine the E rcrev of similar and dissimilar metal crevices in the engineered barrier system of the potential Yucca Mountain repository in 0.5 M NaCl, 4 M NaCl, and 4 M MgCl 2 solutions at 95 deg. C. The results were compared with data previously obtained using crevices formed between Alloy 22 and polytetrafluoroethylene. It was observed that, except for Type 316L stainless steel, all other metal-to-metal crevices were less susceptible to crevice corrosion than the corresponding metal-to-polytetrafluoroethylene crevices. Measurements of galvanic coupling were used to evaluate the crevice corrosion propagation behavior in 5 M NaCl solution at 95 deg. C. The crevice specimens were coupled to either an Alloy 22 or a Titanium Grade 7 plate using metal or polytetrafluoroethylene crevice washers. Crevice corrosion of Type 316L stainless steel propagated without repassivation. For all the tests using a polytetrafluoroethylene crevice washer, crevice corrosion of Alloy 22 was initiated at open circuit potential by the addition of CuCl 2 as an oxidant, whereas no crevice corrosion of Alloy 22 was initiated for all the tests using Alloy 22 or Titanium Grade 7 metals as crevice washer. However, crevice corrosion propagation was found to be very limited under such test conditions

  8. Study on mechanical stability of engineered barrier system for deep geological isolation of high-level radioactive waste

    International Nuclear Information System (INIS)

    Saotome, A.; Hara, K.; Fujita, T.; Sasaki, N.

    1991-01-01

    The evaluation of mechanical and hydraulic behavior of buffer material of engineered barrier system under water uptake was carried out by applying swelling-elasto-plastic model to the buffer material, of which swelling pressure was described by swelling coefficient. The result is that displacement of overpack and deformation of buffer material are negligibly small. The analysis on overpack sinking behavior within buffer material was carried out as the creep deformation of the buffer material. The analysis shows that creep sinking of overpack within buffer material is negligibly small if the density of buffer material is taken to some extent. The effects of dilatation of corrosion products by hydrogen-generating corrosion of carbon steel overpack was studied, because the dilatation is not negligible in a long-term period of time. As the results of elasto-plastic analysis, stress generated by the dilatation is absorbed within buffer material and dose not affect the host rock if the buffer material is packed to some extent in thickness. It is important to assess the migration of hydrogen within the buffer material. Based on the results of thermal calculations in the near-field maximum temperature acceptable to the buffer material can be controlled by the spacing of the waste package. The temperature in the near-field in case of avoiding the illitization of the buffer material is not so high as to affect the waste glass and the host rock. (author)

  9. Technical note. SR-Site Independent Modelling of Engineered Barrier Evolution and Coupled THMC. Contribution to the Initial Review Phase

    Energy Technology Data Exchange (ETDEWEB)

    Benbow, Steven; Metcalfe, Richard; Watson, Claire; Bond, Alex [Quintessa Ltd, Henley on Thames (United Kingdom)

    2012-11-01

    This review has focussed mainly on the modelling of the Engineered Barrier System (EBS) evolution, which includes coupled thermal, hydraulic, mechanical and chemical (THMC) processes. Additionally, the role of the EBS in the wider safety case was reviewed, including its treatment in scenarios and its representation in conceptual models since this provided the motivation for the modelling work that was undertaken by SKB. The scope of the work described here was to: 1. Review relevant documents concerning SKB's modelling; and 2. Check one particular modelling area that was judged to be important, based on this review, with a limited set of independent modelling/calculations. The review covers the early resaturation and swelling / homogenisation of the buffer; the longer-term chemical evolution of the buffer and backfill, corrosion of the copper canister and the chemical and hydrogeological boundary conditions provided by the surrounding host rock. The reviewers consider that SKB's modelling of engineered barrier performance generally supports their conclusion that the barriers will perform as required. However, there remain issues that are not addressed and uncertainties that are not explored adequately by SKB's modelling. The thermo-hydro-mechanical modelling of buffer resaturation that is performed by SKB is based on demonstrating a fit to measurements from the in-situ Canister Retrieval Test (CRT) experiment. The modelling reproduces some of the experimental observations very well, but some key experimental measurements are not considered. In particular, investigation of the fit to the measured rates of water inflow, which are a critical factor controlling the rate at which the buffer will resaturate, is not given, Furthermore, the water supply boundary conditions imposed on the CRT are not considered to be representative of those that might be expected in repository conditions. From the information that it is presented it is therefore not possible

  10. Mont Terri Project - Heater experiment, engineered barriers emplacement and ventilations tests. No 1 - Swiss Geological Survey, Bern, 2007

    International Nuclear Information System (INIS)

    Bossart, P.; Nussbaum, C.

    2007-01-01

    The international Mont Terri project started in January 1996. Research is carried out in the Mont Terri rock laboratory, an underground facility near the security gallery of the Mont Terri motorway tunnel (vicinity of St-Ursanne, Canton of Jura, Switzerland). The aim of the project is the geological, hydrogeological, geochemical and geotechnical characterisation of a clay formation, specifically of the Opalinus Clay. Twelve Partners from European countries and Japan participate in the project. These are ANDRA, BGR, CRIEPI, ENRESA, GRS, HSK, IRSN, JAEA, NAGRA, OBAYASHI, SCK.CEN and swisstopo. Since 2006, swisstopo acts as operator of the rock laboratory and is responsible for the implementation of the research programme decided by the partners. The three following reports are milestones in the research history of the Mont Terri project. It was the first time that an in-situ heating test with about 20 observation boreholes over a time span of several years was carried out in a clay formation. The engineered barrier emplacement experiment has been extended due to very encouraging measurement results and is still going on. The ventilation test was and is a challenge, especially in the very narrow microtunnel. All three projects were financially supported by the European Commission and the Swiss State Secretariat for Education and Research. The three important scientific and technical reports, which are presented in the following, have been provided by a number of scientists, engineers and technicians from the Partners, but also from national research organisations and private contractors. Many fruitful meetings where held, at the rock laboratory and at other facilities, not to forget the weeks and months of installation and testing work carried out by the technicians and engineers. The corresponding names and organisations are listed in detail in the reports. Special thanks are going to the co-ordinators of the three projects for their motivation of the team during

  11. Self-Assembly of Alkylammonium Chains on Montmorillonite: Effect of Interlayer Cations, CEC, and Chain Length

    Science.gov (United States)

    Chen, Hua; Li, Yingjun; Zhou, Yuanlin; Wang, Shanqiang; Zheng, Jian; He, Jiacai

    2017-12-01

    Recently, polymeric materials have been filled with synthetic or natural inorganic compounds in order to improve their properties. Especially, polymer clay nanocomposites have attracted both academic and industrial attention. Currently, the structure and physical phenomena of organoclays at molecular level are difficultly explained by existing experimental techniques. In this work, molecular dynamics (MD) simulation was executed using the CLAYFF and CHARMM force fields to evaluate the structural properties of organoclay such as basal spacing, interlayer density, energy and the arrangement of alkyl chains in the interlayer spacing. Our results are in good agreement with available experimental or other simulation data. The effects of interlayer cations (Na+, K+, Ca2+), the cation exchange capacity, and the alkyl chain length on the basal spacing and the structural properties are estimated. These simulations are expected to presage the microstructure of organo-montmorillonite and lead relevant engineering applications.

  12. Mont Terri Project - Engineered barrier emplacement experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories

    International Nuclear Information System (INIS)

    Mayor, J. C.; Garcia-Sineriz, J.; Alonso, E.; Alheid, H.-J.; Bluemling, P.

    2007-01-01

    The Engineered Barrier (EB) experiment was a full-scale test for the demonstration, in a horizontal drift, of an emplacement technics of the clay barrier, using a granular bentonite material in the upper part of this barrier and bentonite blocks at the bottom. The test has been carried out in a 6 m long section of a niche excavated in Opalinus Clay of the Mont Terri underground laboratory. A steel dummy canister, with the same dimensions and weight as the real reference canisters, was placed on top of a bed of highly compacted bentonite blocks (in turn lying on a concrete bed), and the rest of the clay barrier volume was backfilled with a Granular Bentonite Material (GBM), made of very highly compacted pellets of different sizes. Hydro-mechanical instrumentation and an artificial hydration system (to accelerate the saturation of the clay barrier) were installed, and the test section sealed with a concrete plug. The evolution of the hydro-mechanical parameters along the hydration, both in the barrier and in the clayey rock formation, has been monitored during about 1.5 years, and modelled using the CODE-BRIGHT code. The EB experiment has proved that fully automated production of a Granular Bentonite Material (GBM) is possible and large quantities can be produced in due time in the required quality. Only minor modifications of existing production lines in industry for other applications were necessary to achieve this result. In the EB test section, a dry density of 1.36 g/cm 3 of the emplaced GBM has been obtained. With this value it is estimated that the hydraulic conductivity of this material is lower than 5 x 10 -12 m/s and the swelling pressure is about 1.3 MPa. Even though the EB test section conditions are now not considered as representative of a true demonstration, it is deemed that the model emplacement testing results (dry density of about 1.40 g/cm 3 ) serve well to demonstrate the achievable densities expected in the real world setting. The artificial

  13. Mont Terri Project - Engineered barrier emplacement experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories

    Energy Technology Data Exchange (ETDEWEB)

    Mayor, J. C. [Empresa Nacional de Residuos Radioactivos SA (ENRESA), Madrid (Spain); Garcia-Sineriz, J. [Asociacion para la Investigacion y Desarollo Industrial de los Recursos Naturales (AITEMIN), Madrid (Spain); Alonso, E. [Centre Internacional de Metodos Numerics en Ingenyeria (CIMNE), Barcelona (Spain); Alheid, H.-J. [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany); Bluemling, P. [National Cooperative for the Disposal of Radioactive Waste (Nagra), Wettingen (Switzerland)

    2007-07-01

    The Engineered Barrier (EB) experiment was a full-scale test for the demonstration, in a horizontal drift, of an emplacement technics of the clay barrier, using a granular bentonite material in the upper part of this barrier and bentonite blocks at the bottom. The test has been carried out in a 6 m long section of a niche excavated in Opalinus Clay of the Mont Terri underground laboratory. A steel dummy canister, with the same dimensions and weight as the real reference canisters, was placed on top of a bed of highly compacted bentonite blocks (in turn lying on a concrete bed), and the rest of the clay barrier volume was backfilled with a Granular Bentonite Material (GBM), made of very highly compacted pellets of different sizes. Hydro-mechanical instrumentation and an artificial hydration system (to accelerate the saturation of the clay barrier) were installed, and the test section sealed with a concrete plug. The evolution of the hydro-mechanical parameters along the hydration, both in the barrier and in the clayey rock formation, has been monitored during about 1.5 years, and modelled using the CODE-BRIGHT code. The EB experiment has proved that fully automated production of a Granular Bentonite Material (GBM) is possible and large quantities can be produced in due time in the required quality. Only minor modifications of existing production lines in industry for other applications were necessary to achieve this result. In the EB test section, a dry density of 1.36 g/cm{sup 3} of the emplaced GBM has been obtained. With this value it is estimated that the hydraulic conductivity of this material is lower than 5 x 10{sup -12} m/s and the swelling pressure is about 1.3 MPa. Even though the EB test section conditions are now not considered as representative of a true demonstration, it is deemed that the model emplacement testing results (dry density of about 1.40 g/cm{sup 3}) serve well to demonstrate the achievable densities expected in the real world setting. The

  14. THERMODINAMIC PARAMETERS ON THE SORPTION OF PHOSPHATE IONS BY MONTMORILLONITE

    Directory of Open Access Journals (Sweden)

    Ikhsan Jaslin

    2016-04-01

    Full Text Available The sorption of phosphate by montmorillonite at 10, 30, and 50 oC were investigated aiming to mainly determine thermodynamic parameters for the formation of surface complexes in the adsorption of phosphate ions by montmorillonite. Data were collected by adsorption edge experiments investigating the effect of pH, adsorption isotherms enabling the effect of sorbate concentration, and acid-base titration calculating protons released or taken up by adsorption process. Data analysis was carried out using surface complexation model to fit the data collected in this study using the parameters obtained from previous study, as well as to calculate the values of ΔH and ΔS. Previous study reported that phosphate ions formed two outer-sphere surface complexes with active sites of montmorillonite through hydrogen bonding. In the first complex,  [(XH0– H2L─]─, the phosphate was held to permanent-charge X─ sites on the tetrahedral siloxane faces, and the second complex, [[(SO─(SOH]– – [H2L]─] 2─ was formed through the interaction between the phosphate and variable charge surface hydroxyl groups at the edges of montmorillonite crystals and on the octahedral alumina faces. The values of ΔH for the first and second reactions are 39.756 and 3.765x10-7 kJ mol‒1 respectively. Since both reactions have positive enthalpy values, it can be concluded that the reactions are endothermic. Large energy for the first reaction is needed by X─  sites (permanent negatively charge sites of montmorillonite to be partially desolvated, on which K+ or other surface cations are replaced by H+ ions in the surface protonated process, and are then ready to interact phosphate ions in the solution. Small values of ΔH for the second reactions indicates that hydrogen bonds formed by phosphate and SOH sites in the second reaction are easily broken out, and the phosphate can easily desorbed from the surface. The values of ΔS for the first and second reactions are

  15. Development of mechanistic sorption model and treatment of uncertainties for Ni sorption on montmorillonite/bentonite

    International Nuclear Information System (INIS)

    Ochs, Michael; Ganter, Charlotte; Tachi, Yukio; Suyama, Tadahiro; Yui, Mikazu

    2011-02-01

    Sorption and diffusion of radionuclides in buffer materials (bentonite) are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in this barrier is expected to be diffusion-controlled and retarded by sorption processes. It is therefore necessary to understand the detailed/coupled processes of sorption and diffusion in compacted bentonite and develop mechanistic /predictive models, so that reliable parameters can be set under a variety of geochemical conditions relevant to performance assessment (PA). For this purpose, JAEA has developed the integrated sorption and diffusion (ISD) model/database in montmorillonite/bentonite systems. The main goal of the mechanistic model/database development is to provide a tool for a consistent explanation, prediction, and uncertainty assessment of K d as well as diffusion parameters needed for the quantification of radionuclide transport. The present report focuses on developing the thermodynamic sorption model (TSM) and on the quantification and handling of model uncertainties in applications, based on illustrating by example of Ni sorption on montmorillonite/bentonite. This includes 1) a summary of the present state of the art of thermodynamic sorption modeling, 2) a discussion of the selection of surface species and model design appropriate for the present purpose, 3) possible sources and representations of TSM uncertainties, and 4) details of modeling, testing and uncertainty evaluation for Ni sorption. Two fundamentally different approaches are presented and compared for representing TSM uncertainties: 1) TSM parameter uncertainties calculated by FITEQL optimization routines and some statistical procedure, 2) overall error estimated by direct comparison of modeled and experimental K d values. The overall error in K d is viewed as the best representation of model uncertainty in ISD model/database development. (author)

  16. Sorption behavior of thorium onto montmorillonite and illite

    International Nuclear Information System (INIS)

    Iida, Yoshihisa; Barr, Logan; Yamaguchi, Tetsuji; Hemmi, Ko

    2016-01-01

    Thorium (Th)-229 is one of the important radionuclides for the performance assessment calculations for high-level radioactive waste repositories. The sorption behavior of Th onto montmorillonite and illite were investigated by batch sorption experiments. Experiments were carried out under variable pH and carbonate concentrations. The sorbability of montmorillonite was higher than that of illite. Distribution coefficients, K d (m 3 kg -1 ), decreased with increased carbonate concentrations and showed the minimal value at around pH 10. The sorption behaviors of Th were analyzed by the non-electrostatic surface complex model with PHREEQC computer program. The model calculations were able to explain the experimental results reasonably well. The decreases of K d was likely due to the stabilization of aqueous species by hydroxo-carbonate complexations in the solutions. (author) [ja

  17. Use of the montmorillonite as crosslink agents for chitosan

    International Nuclear Information System (INIS)

    Barbosa, Rossemberg C.; Lima, Rosemary S. Cunha; Braga, Carla R. Costa; Fook, Marcus V. Lia; Silva, Suedina M. Lima

    2009-01-01

    The montmorillonite (the main constituent of bentonite) has been the most commonly used inorganic load in the formation of nanocomposites chitosan / layered silicate. To evaluate its effect as an agent for the reticulation of chitosan, a sodium montmorillonite, Cloisite Na + , supplied by Southern Clay Products, Texas, USA, was used. For the reticulation of chitosan dispersions of chitosan / Cloisite Na + were prepared in different proportions and the obtained films characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TG). The results indicated that the Cloisite Na + was for efficient and the reticulation of the chitosan and can be used in place of sulfuric acid, which is one of the most common reticulants for chitosan. (author)

  18. Silver nanoparticles in montmorillonite to application in polymeric materials

    International Nuclear Information System (INIS)

    Morita, R.Y.; Barbosa, R.V.; Kloss, J.R.; Schnitzler, M.; Garcia, J.

    2012-01-01

    This work presents the preparation of silver nanoparticles (AgNPs) through industrially viable methodologies and free of organic solvents, and their insertion in montmorillonite, to produce a nanomaterial with bactericidal properties. The modified montmorillonite was characterized through the techniques of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and x-ray diffraction (XRD). The FTIR and Raman spectrum's showed specific bands of involving stretching silver. In the XRD analyses was observed the occurrence of the following crystallographic planes (111), (200) e (220) silver related. For application in low density polyethylene, the mechanical tests showed no loss in the mechanical properties, when the AgNPs is present, this fact is important and indicate that the nanomaterial can be inserted in this polymer matrix with considerable technology interest. (author)

  19. Nontronite and Montmorillonite as Nutrient Sources for Life on Mars

    Science.gov (United States)

    Craig, P. I.; Mickol, R. L.; Archer, P. D.; Kral, T. A.

    2017-01-01

    Clay minerals have been identified on Mars' oldest (Noachian) terrain and their presence suggests long-term water-rock interactions. The most commonly identified clay minerals on Mars to date are nontronite (Fe-smectite) and montmorillonite (Al-smectite) [1], both of which contain variable amounts of water both adsorbed on their surface and within their structural layers. Over Mars' history, these clay miner-al-water assemblages may have served as nutrient sources for microbial life.

  20. Assessment of the Effectiveness of Clay Soil Covers as Engineered Barriers in Waste Disposal Facilities with Emphasis on Modeling Cracking Behavior

    Science.gov (United States)

    2008-06-01

    standard proctor hammer (ASTM D698), which was dropped a sufficient number of times to achieve the desired dry density ERDC TR-08-7 34 Figure...using a standard proctor hammer to an equivalent dry density as was found in Experiment 1. ERDC TR-08-7 45 Figure 25. Sample container for...ER D C TR -0 8- 7 Assessment of the Effectiveness of Clay Soil Covers as Engineered Barriers in Waste Disposal Facilities with Emphasis

  1. Engineered Barrier System - Mechanical Integrity of KBS-3 Spent Fuel Canisters. Report from a Workshop. Synthesis and extended abstracts

    Energy Technology Data Exchange (ETDEWEB)

    2007-09-15

    SKI is preparing to review the license applications being developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) for a final repository for the geological disposal of spent nuclear fuel in the year 2009. As part of its preparation, SKI is conducting a series of technical workshops on key aspects of the Engineered Barrier System (EBS). The workshop reported here mainly dealt with the mechanical integrity of KBS-3 spent fuel canisters. This included assessment and review of various loading conditions, structural integrity models and mechanical properties of the copper shell and the cast iron insert. Degradation mechanisms such as stress corrosion cracking and brittle creep fracture were also briefly addressed. Previous workshops have addressed the overall concept for long-term integrity of the EBS, the manufacturing, testing and QA of the EBS, the performance confirmation for the EBS, long-term stability of the buffer and the backfill, corrosion properties of copper canisters and the spent fuel dissolution and source term modelling. The goal of ongoing review work in connection of the workshop series is to achieve a comprehensive overview of all aspects of SKB's EBS and spent fuel work prior to the handling of the forthcoming license application. This report aims to summarise the issues discussed at the workshop and to extract the essential viewpoints that have been expressed. The report is not a comprehensive record of all the discussions at the workshop, and individual statements made by workshop participants should be regarded as personal opinions rather than SKI viewpoints. Results from the EBS workshops series will be used as one important basis in future review work. This reports includes in addition to the workshop synthesis, questions to SKB identified prior to the workshop, and extended abstracts for introductory presentations

  2. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chih-Jen [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, University of Wisconsin - Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jean, Jiin-Shuh; Liu, Chia-Chuan [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2010-11-15

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca{sup 2+} as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK{sub a2} (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d{sub 001}) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  3. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    International Nuclear Information System (INIS)

    Wang, Chih-Jen; Li, Zhaohui; Jiang, Wei-Teh; Jean, Jiin-Shuh; Liu, Chia-Chuan

    2010-01-01

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca 2+ as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK a2 (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d 001 ) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  4. Controlled release of agrochemicals intercalated into montmorillonite interlayer space.

    Science.gov (United States)

    Wanyika, Harrison

    2014-01-01

    Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil.

  5. Ability of Cu2+-montmorillonite to accept an toxic pollutants

    International Nuclear Information System (INIS)

    Janikova, V.; Jona, E.; Janik, R.; Pavlik, V.

    2015-01-01

    It is global problem that toxic pollutants are in the permanent contact to people through soil and water. Nowadays, it is important to eliminate these pollutants for future generations and to keep environment in the health condition. In relation to this article, aromatic organic compounds like benzene, phenol and aniline were chosen. These are used in various branches of industry, mainly in rubber industry or for production of dyes and in addition, phenol is commonly used in cosmetics or in food industry. Montmorillonite is clay mineral consisting of 2:1 sheets (tetrahedral:octahedral) and interlayer space where exchangeable cations and water molecules are present. Due to its structure, montmorillonite is able to accept some compounds or pollutants. This is the reason why it is mainly used as the covering material of radioactive waste in order to remove toxic pollutants. For investigation of toxic pollutants removing, XRD powder diffraction, infrared spectroscopy and thermal analysis were used. Our results show that Cu 2+ -montmorillonite is able to accept toxic benzene ring-based pollutants into interlayer. This mentioned ability can be proven on the basis of the investigation results relating to difference of interlayer distance, typical frequencies of -OH group or -NH 2 group, while these results were supplemented by thermal properties. (authors)

  6. Characterization of poly pyrrole/montmorillonite electro polymerised onto Pt

    International Nuclear Information System (INIS)

    Castagno, K.R.L.; Azambuja, D.S.; Dalmoro, V.; Mauller, R.S.

    2010-01-01

    In this study films of polypyrrole/montmorillonite (PPy/MT) were electropolymerized on platinum in order to evaluate the performance of this technique in the preparation of nanocomposite materials and to determine the thermal properties and conductivity of the composites. The films were synthesized from a solution containing pyrrole, dodecylbenzene sulfonate, acid and two types of clays: montmorillonite-Na + (MT-Na) and montmorillonite-30B (MT-M). The characterization of the films we have used FT-IR, TEM, XRD, TGA, DSC and resistivity measurement by the four-point van der Pauw method. The study showed that the adopted method of exfoliation and the electropolymerization method used, allows obtaining nanocomposite materials. Analyses of FT-IR, TEM and XRD show that the clays are exfoliated in the polymer matrix. Thermal analysis of the films indicates that the addition of clay reflects an enhancement in the thermal properties of the matrix of PPy, but decreases the conductivity of the same. (author)

  7. Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

    Science.gov (United States)

    Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

    2016-12-01

    The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10-6 cm2/s and 2.67 × 10-6 cm2/s.

  8. Synthesis of a Biglucoside and Its Application as Montmorillonite Hydration Inhibitor

    Directory of Open Access Journals (Sweden)

    Xin-chun Zhang

    2014-01-01

    Full Text Available A biglucoside (BG was synthesized with glucose and epichlorohydrin as raw materials. The inhibition of BG against montmorillonite swelling was investigated by various methods including montmorillonite linear expansion test, mud ball immersing test, thermogravimetric analysis, and scanning electron microscopy. The results show that the BG has good inhibition ability to the hydration swelling and dispersion of montmorillonite. Under the same condition, the linear expansion ratio of montmorillonite in BG solution is much lower than that of MEG. The particle distribution measurement, thermogravimetric analysis, FT-IR, and scanning electron microscopy results all prove the efficient inhibition of BG.

  9. Effects of thermal barrier coating on gas emissions and performance of a LHR engine with different injection timings and valve adjustments

    International Nuclear Information System (INIS)

    Bueyuekkaya, Ekrem; Engin, Tahsin; Cerit, Muhammet

    2006-01-01

    Tests were performed on a six cylinder, direct injection, turbocharged Diesel engine whose pistons were coated with a 350 μm thickness of MgZrO 3 over a 150 μm thickness of NiCrAl bond coat. CaZrO 3 was employed as the coating material for the cylinder head and valves. The working conditions for the standard engine (uncovered) and low heat rejection (LHR) engine were kept exactly the same to ensure a realistic comparison between the two configurations of the engine. Comparisons between the standard engine and its LHR version were made based on engine performance, exhaust gas emissions, injection timing and valve adjustment. The results showed that 1-8% reduction in brake specific fuel consumption could be achieved by the combined effect of the thermal barrier coating (TBC) and injection timing. On the other hand, NO x emissions were obtained below those of the base engine by 11% for 18 o BTDC injection timing

  10. Montmorillonite dissolution kinetics: Experimental and reactive transport modeling interpretation

    Science.gov (United States)

    Cappelli, Chiara; Yokoyama, Shingo; Cama, Jordi; Huertas, F. Javier

    2018-04-01

    The dissolution kinetics of K-montmorillonite was studied at 25 °C, acidic pH (2-4) and 0.01 M ionic strength by means of well-mixed flow-through experiments. The variations of Si, Al and Mg over time resulted in high releases of Si and Mg and Al deficit, which yielded long periods of incongruent dissolution before reaching stoichiometric steady state. This behavior was caused by simultaneous dissolution of nanoparticles and cation exchange between the interlayer K and released Ca, Mg and Al and H. Since Si was only involved in the dissolution reaction, it was used to calculate steady-state dissolution rates, RSi, over a wide solution saturation state (ΔGr ranged from -5 to -40 kcal mol-1). The effects of pH and the degree of undersaturation (ΔGr) on the K-montmorillonite dissolution rate were determined using RSi. Employing dissolution rates farthest from equilibrium, the catalytic pH effect on the K-montmorillonite dissolution rate was expressed as Rdiss = k·aH0.56±0.05 whereas using all dissolution rates, the ΔGr effect was expressed as a non-linear f(ΔGr) function Rdiss = k · [1 - exp(-3.8 × 10-4 · (|ΔGr|/RT)2.13)] The functionality of this expression is similar to the equations reported for dissolution of Na-montmorillonite at pH 3 and 50 °C (Metz, 2001) and Na-K-Ca-montmorillonite at pH 9 and 80 °C (Cama et al., 2000; Marty et al., 2011), which lends support to the use of a single f(ΔGr) term to calculate the rate over the pH range 0-14. Thus, we propose a rate law that also accounts for the effect of pOH and temperature by using the pOH-rate dependence and the apparent activation energy proposed by Rozalén et al. (2008) and Amram and Ganor (2005), respectively, and normalizing the dissolution rate constant with the edge surface area of the K-montmorillonite. 1D reactive transport simulations of the experimental data were performed using the Crunchflow code (Steefel et al., 2015) to quantitatively interpret the evolution of the released cations

  11. The field migration tests of 237Np, 238Pu, 241Am and 90Sr in aerated loess, aquifer and engineering barrier materials

    International Nuclear Information System (INIS)

    Li Shushen; Wang Zhiming; Zhao Yingjie; Fan Zhiwen; Liu Chunli; An Yongfeng; Yang Yue'e; Wu Qinghua

    2003-01-01

    This paper introduces the field migration tests of 237 Np, 238 Pu, 241 Am and 90 Sr in aerated loess, aquifer and engineering barrier materials. The tests in the aerated loess and engineering barrier materials were carried out under both natural and artificial sprinkling (15 mm/d) conditions. The tests in aquifer were carried out in both assemblies packed with undisturbed aquifer media and a definite undisturbed area. The results indicate that after 3 years tests no significant migrations were seen for all nuclides in engineering barrier materials under two kinds of conditions and in aerated loess under natural conditions. For the aerated loess under artificial sprinkling conditions, 2.7 cm (center of mass) migration in the area directly below the sand tracer layer (named as area 1) and 13 cm (peak) migration in the area outside the area 1 for 90 Sr were observed; There was no migration for 237 Np, 238 Pu and 241 Am. It was discovered that the sand layer used as carrier of nuclide tracer has barrier effect on unsaturated water and an influence on nuclide migration. This has been demonstrated by the inter comparison experiment with both sand and loess as tracer carrier. In the tracer tests of undisturbed aquifer area there was no significant migration of 237 Np, 238 Pu, 241 Am and 90 Sr after 1023 days. In the assembly 8 there was no significant migration for 238 Pu and 241 Am and a small backward migration 0.95 cm for 237 Np and 4.7 cm migration (center of mass) for 90 Sr were observed. The tests also indicate that there is no significant difference of nuclide migration in ordinary and degraded cement

  12. Influence of temperature on pentavalent Np Sorption and desorption onto Goethite, Montmorillonite

    International Nuclear Information System (INIS)

    Vial, M.A.; Sherman, C; Czerwinski, K.R.; Reed, D.

    2002-01-01

    Yucca Mountain Site has been selected by the United States Department of Energy as the repository for disposing the US HLW. The performance allocation analysis on a multi-barrier system for high-level radioactive waste disposal has pointed 237 Np as the dominant hazard at the inlet of the biosphere [1J. 2JNp is present in high-level radioactive wastes (HLW), although in smaller amounts in comparison to other radionuclides. Because of its long half-life of 2.14 million years and its mobile nature under aerobic conditions due to the high chemical stability of its pentavalent state, it is considered a possible long-term pollutant of the ecosystem. Understanding Np behavior is required in order to quantitatively describe its transport in surface groundwater systems. In the repository, many components are known to play an important role in Np and other actinides speciation through adsorption-, complexation-, dissolution-, precipitation- and, colloids or pseudocolloids generation reactions [1]. Inorganic Ligands (C0 3 - , OH - ), present in nearly all natural water at various degree, and organic ligands (humic acid) can react with Np and consequently affect its leachability through the formation of numerous compounds. The solubility limits of radionuclides may act as an initial barrier to radionuclide migration from the potential repository at Yucca Mountain for some radionuclides. However, once radionuclides have dissolved in water infiltrating the site, sorption of these radionuclides onto the surrounding mineral phases becomes a potentially important second barrier. The study of retardation of Np and other key actinides is of major importance in assessing the performance of the potential repository. Among the soil of interest montmorillonite and iron-based materials have generated lots of researches. Nagasaki et al. [2] recent researches on sorption equilibrium and kinetics of NpO 2 + on dispersed particles of Na-montmorillonite and Na-illite (batch experiments at p

  13. Wheat gluten/montmorillonite biocomposites: Effect of pH on the mechanical properties and clay dispersion

    Directory of Open Access Journals (Sweden)

    E. Cortes-Trivino

    2018-07-01

    Full Text Available The addition of inorganic fillers into a bioplastic could increase its mechanical properties, which will be influenced strongly by the type of the clay dispersion. In this work, we have used montmorillonite nanoclays (MMT to prepare biocomposites by means of an extrusion process. We present herein the effect of the pH and the addition of montmorillonite nanoclays (MMT on the barrier and mechanical properties of wheat gluten based bioplastics. The pH of the samples was modified by adding aqueous solution of a strong acid or base (H2SO4 and NaOH. Tensile, dynamic mechanical thermal analysis (DMTA, water absorption and X-ray tests were carried out to study the influence of the above-mentioned variables on the physicochemical properties and rheological behaviour of bioplastics and biocomposites obtained. Tensile results showed that both Young’s modulus and tensile strength are higher at unmodified pH. However, the addition of MMT to an alkaline biopolymer matrix produced remarkable improvements in the rheological and mechanical properties because of a high exfoliation of the nanoclay noticeable in X-ray results. To summarise, extrusion process and the use of nanoclays present an excellent opportunity to develop wheat gluten bioplastics able to replace conventional products.

  14. Women Break an Engineering Barrier: While Other Engineering Disciplines Stumble, BME Represents a Success Story in Attracting American Women to a Male-Dominated Field.

    Science.gov (United States)

    Gutierrez, Claudia; Paulosky, Meaghan; Aguinaldo, Angeline; Gerhart, Jackie

    2017-01-01

    While the field of engineering as a whole is largely male-dominated, biomedical engineering (BME) is one area poised to overturn this trend. Women in the United States were awarded only 20% of all engineering B.S. degrees in 2015; in BME, however, 40.9% of the degree recipients were women. This stands in stark contrast to the more traditional fields of mechanical and electrical engineering, where women were awarded just 13.2% and 12.5% of B.S. degrees, respectively. This trend toward more female participation in BME continues at both the M.S. and Ph.D. degree levels. In fact, in 2015, BME had the highest percentage of female engineering M.S. degree recipients in the United States of all engineering disciplines, according to the American Society for Engineering Education (Figure 1).

  15. Sorption of prioritized elements on montmorillonite colloids and their potential to transport radionuclides

    International Nuclear Information System (INIS)

    Wold, Susanna

    2010-04-01

    Due to colloids potential to bind radionuclides (RN) and even mobilise sorbed RN, colloid transport of RN should be taken into account when modeling radionuclide transport in the scenario of a leaking canister in a deep bedrock repository of spent nuclear fuel. Colloids are always present in natural waters and the concentrations are controlled by the groundwater chemistry where specifically the ionic strength is of major importance. In many deep bedrock groundwaters, the ionic strength is fairly high (above the Critical Coagulation Concentration) and therefore colloids are not likely to be stable. In these types of groundwaters colloid concentrations up to 100 μg/l could be expected, and clay colloids organic degradation products and bacteria and viruses represent can be found. In a long time perspective cycles of glaciations can be expected in Sweden as in other Nordic countries. It can not be excluded that glacial melt water can intrude to repository depth with high flows. In this scenario the groundwater conditions may drastically change. In contact with dilute groundwater the bentonite barrier can start to propagate a bentonite gel and further release montmorillonite colloids into water bearing fractures. The concentration of colloids in vicinity of the bentonite barrier can then increase drastically. In contact with Grimsel groundwater types with [Na] and [Ca] of 0.001 and 0.0001 M respectively a montmorillonite concentration of a maximum of 20 mg/l is expected. Further, the groundwater chemistry of Grimsel seems to be representative for glacial meltwater when comparing with the water chemistry data on meltwaters from existing glaciers. A key to be able to model colloid transport of radionuclides is the sorption strength and the sorption reversibility. To facilitate this, a compilation of literature K d -values and an inventory of available sorption kinetic data has been composed for the prioritized elements Pu, Th, Am, Pb, Pa, Ra, Np, Cm, Ac, Tc, Cs, Nb, Ni

  16. Sorption of prioritized elements on montmorillonite colloids and their potential to transport radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Wold, Susanna (Royal Inst. of Technology, Stockholm (Sweden). School of Chemical Science and Engineering, Nuclear Chemistry)

    2010-04-15

    Due to colloids potential to bind radionuclides (RN) and even mobilise sorbed RN, colloid transport of RN should be taken into account when modeling radionuclide transport in the scenario of a leaking canister in a deep bedrock repository of spent nuclear fuel. Colloids are always present in natural waters and the concentrations are controlled by the groundwater chemistry where specifically the ionic strength is of major importance. In many deep bedrock groundwaters, the ionic strength is fairly high (above the Critical Coagulation Concentration) and therefore colloids are not likely to be stable. In these types of groundwaters colloid concentrations up to 100 mug/l could be expected, and clay colloids organic degradation products and bacteria and viruses represent can be found. In a long time perspective cycles of glaciations can be expected in Sweden as in other Nordic countries. It can not be excluded that glacial melt water can intrude to repository depth with high flows. In this scenario the groundwater conditions may drastically change. In contact with dilute groundwater the bentonite barrier can start to propagate a bentonite gel and further release montmorillonite colloids into water bearing fractures. The concentration of colloids in vicinity of the bentonite barrier can then increase drastically. In contact with Grimsel groundwater types with [Na] and [Ca] of 0.001 and 0.0001 M respectively a montmorillonite concentration of a maximum of 20 mg/l is expected. Further, the groundwater chemistry of Grimsel seems to be representative for glacial meltwater when comparing with the water chemistry data on meltwaters from existing glaciers. A key to be able to model colloid transport of radionuclides is the sorption strength and the sorption reversibility. To facilitate this, a compilation of literature K{sub d}-values and an inventory of available sorption kinetic data has been composed for the prioritized elements Pu, Th, Am, Pb, Pa, Ra, Np, Cm, Ac, Tc, Cs, Nb

  17. Effects of humidity and interlayer cations on the frictional strength of montmorillonite

    Science.gov (United States)

    Tetsuka, Hiroshi; Katayama, Ikuo; Sakuma, Hiroshi; Tamura, Kenji

    2018-04-01

    We developed a humidity control system in a biaxial friction testing machine to investigate the effect of relative humidity and interlayer cations on the frictional strength of montmorillonite. We carried out the frictional experiments on Na- and Ca-montmorillonite under controlled relative humidities (ca. 10, 30, 50, 70, and 90%) and at a constant temperature (95 °C). Our experimental results show that frictional strengths of both Na- and Ca-montmorillonite decrease systematically with increasing relative humidity. The friction coefficients of Na-montmorillonite decrease from 0.33 (at relative humidity of 10%) to 0.06 (at relative humidity of 93%) and those of Ca-montmorillonite decrease from 0.22 (at relative humidity of 11%) to 0.04 (at relative humidity of 91%). Our results also show that the frictional strength of Na-montmorillonite is higher than that of Ca-montmorillonite at a given relative humidity. These results reveal that the frictional strength of montmorillonite is sensitive to hydration state and interlayer cation species, suggesting that the strength of faults containing these clay minerals depends on the physical and chemical environment.[Figure not available: see fulltext.

  18. The application of modified montmorillonite in the processes of baromembrane purification of water from U (VI)

    International Nuclear Information System (INIS)

    Yurlova, L.Yu.; Krivoruchko, A.P.

    2010-01-01

    The processes of uranium-containing water purification by ultra- and nanofiltration methods combined with the use of montmorillonite modified by polyethyleneimine are studied. It is shown that the application of montmorillonite allows one to obtain the high indices of the uranium-containing water purification by baromembrane methods.

  19. Fixation of enzyme protein in soil by the clay mineral montmorillonite

    DEFF Research Database (Denmark)

    Sørensen, L.H.

    1969-01-01

    Aminosäureverbindungen, die im Boden während des biologischen Abbaus von Kohlehydraten gebildet und vom Tonmineral Montmorillonit stabilisiert werden, haben Enzymcharakter und sind folglich Proteine.......Aminosäureverbindungen, die im Boden während des biologischen Abbaus von Kohlehydraten gebildet und vom Tonmineral Montmorillonit stabilisiert werden, haben Enzymcharakter und sind folglich Proteine....

  20. Preparation and Characterization of Modified Montmorillonite/Paraffin Phase Change Microcapsules for Energy Storage

    Directory of Open Access Journals (Sweden)

    LIN Sen

    2017-03-01

    Full Text Available The phase change microcapsules of modified montmorillonite/paraffin were prepared by Pickering emulsion method. Analytic techniques of optical microscopy, scanning electron microscopy(SEM, infrared spectroscopy(FTIR, differential scanning calorimetry(DSC and thermogravimetry(TG were utilized for characterizing chemical structure, morphology and thermal properties. Results show that modified montmorillonite as a new type wall material has excellent performance for protecting core material of paraffin. FTIR spectra of phase change of modified montmorillonite/paraffin microcapsules shows that their characteristic peaks match with corresponding peaks of pure paraffin and modified montmorillonite. DSC results indicate that modified montmorillonite/paraffin microcapsules have similar solid-liquid phase change temperature with pure paraffin. The phase transition enthalpy values of microcapsules with paraffin contents varying from 55% to 80% are 110.5-147.2J/g, indicating that microcapsules have excellent thermal storage performance and the phase change properties can be adjusted by changing contents of paraffin. TG results confirm that modified montmorillonite/paraffin microcapsules have outstanding thermal stability. The presented study indicates that modified montmorillonite is a suitable wall material for preparing paraffin microcapsule. Modified montmorillonite/paraffin microcapsules have advantages of low cost and high performance with a great application potential in the field of thermal storage.

  1. Adsorption of Carbon Dioxide, Methane, and Their Mixtute by Montmorillonite in the Presence of Water

    KAUST Repository

    Kadoura, Ahmad Salim; Nair, Arun Kumar Narayanan; Sun, Shuyu

    2016-01-01

    Using grand canonical Monte Carlo (GCMC) simulations, we study the adsorption behavior of CH4, CO2, and their mixture at 298.15 K and pressures up to 50 bar in Na-, Cs-, and Ca-montmorillonite clays in the presence of water. Montmorillonite clays

  2. Poro-elasto-plastic behaviour of dry compacted Fo-Ca clay: experiment and modelling. Application to the re-saturation of an engineered clay barrier

    International Nuclear Information System (INIS)

    Lassabatere, Th.; Imbert, Ch.; Etile, M.A.

    1999-01-01

    Many projects of underground repositories for high level radioactive waste involve an engineered clay barrier, placed between the waste canister and the surrounding rock. When hydrated, this barrier seals the gap and provides a good watertightness. The natural clay powder, dried and compacted, exhibits hydro-mechanical couplings during the hydration. Such a coupled behaviour, interesting for the industrial application, has been clearly demonstrated by many studies and laboratory experiments. But the modelling of this behaviour, in order to predict the hydration of the clay barrier, is difficult. A coupled modelling, based, at a macroscopic scale, on the thermodynamics of unsaturated porous media, is proposed. This thermodynamical model founds a general framework for non linear poro-elastic and poro-elasto-plastic coupled behaviours. The symmetries of this coupling, induced by this thermodynamical framework, let us take into account the often neglected influence of the mechanical state on the hydraulic problem of the re-saturation of the clay. The complete resolution of the flow problem, coupled with the mechanical behaviour, leads us to study the influence of the rheological behaviour chosen for the clay (elastic - linear or no linear -, or elastoplastic) on the evaluation of the duration of the re-saturation of the clay barrier). (authors)

  3. Transcytosis in the blood–cerebrospinal fluid barrier of the mouse brain with an engineered receptor/ligand system

    Directory of Open Access Journals (Sweden)

    Héctor R Méndez-Gómez

    Full Text Available Crossing the blood–brain and the blood–cerebrospinal fluid barriers (BCSFB is one of the fundamental challenges in the development of new therapeutic molecules for brain disorders because these barriers prevent entry of most drugs from the blood into the brain. However, some large molecules, like the protein transferrin, cross these barriers using a specific receptor that transports them into the brain. Based on this mechanism, we engineered a receptor/ligand system to overcome the brain barriers by combining the human transferrin receptor with the cohesin domain from Clostridium thermocellum, and we tested the hybrid receptor in the choroid plexus of the mouse brain with a dockerin ligand. By expressing our receptor in choroidal ependymocytes, which are part of the BCSFB, we found that our systemically administrated ligand was able to bind to the receptor and accumulate in ependymocytes, where some of the ligand was transported from the blood side to the brain side.

  4. Preparation of Polypropylene/Montmorillonite Nanocomposites Using Ionizing Radiation

    International Nuclear Information System (INIS)

    Güven, Olgun; Zengin, Fatma

    2011-01-01

    Polymer/clay nanocomposites are new generation materials that bring significant changes in mechanical, thermal and permeation properties of base polymers by low clay loading. In this study, polypropylene/montmorillonite nanocomposites were prepared by melt intercalation method by using batch type mixer. Two polypropylene samples with different melt flow indexes are used as the matrix, maleic anhydride grafted polypropylene (PP-g-MAH), and polypropylene granules oxidized by radiation/ozone are used as compatibilizer and unmodified clay (Na + montmorillonite, MMT) as the filler. Aim of this study is to examine the effect of different compatibilizers in the mechanical properties of polypropylene composite. Firstly, PP/clay samples were prepared and the effect of clay was examined, then 5, 10, 20kGy oxidized/degraded polypropylenes were used as compatibilizer and, 10 kGy was determined to be the most suitable irradiation dose for the best compatibilizing effect. Polypropylene granules were ozonated until they contained carbonyl groups equivalent to 10kGy oxidized PP, which was checked by FTIR-ATR spectroscopy. UV-visible reflectance measurements were also made on film samples and no significant changes were observed in visible region. Nano structures of some nanocomposites were characterized by PALS (Positron Annihilation Lifetime Spectroscopy) where it was observed that the addition of clay decreased the number of free volume holes and free volume hole radia. The dispersion state of MMT within polymer matrix was analyzed by XRD (X-ray diffraction). Tensile tests were made and the effect of the addition of clay and compatibilizers investigated. At low melt flow index PP, 1% MMT of PP/10kGyPP/MMT nanocomposite showed an increase in E-modulus 26% and in tensile strength 8% as compared to those of pristine PP. In conclusion radiation degraded (chain scissioned and oxidized) PP has been found to show very good compatibilizing effect for the natural montmorillonite

  5. Acidity of edge surface sites of montmorillonite and kaolinite

    Science.gov (United States)

    Liu, Xiandong; Lu, Xiancai; Sprik, Michiel; Cheng, Jun; Meijer, Evert Jan; Wang, Rucheng

    2013-09-01

    Acid-base chemistry of clay minerals is central to their interfacial properties, but up to now a quantitative understanding on the surface acidity is still lacking. In this study, with first principles molecular dynamics (FPMD) based vertical energy gap technique, we calculate the acidity constants of surface groups on (0 1 0)-type edges of montmorillonite and kaolinite, which are representatives of 2:1 and 1:1-type clay minerals, respectively. It shows that tbnd Si-OH and tbnd Al-OH2OH groups of kaolinite have pKas of 6.9 and 5.7 and those of montmorillonite have pKas of 7.0 and 8.3, respectively. For each mineral, the calculated pKas are consistent with the experimental ranges derived from fittings of titration curves, indicating that tbnd Si-OH and tbnd Al-OH2OH groups are the major acidic sites responsible to pH-dependent experimental observations. The effect of Mg substitution in montmorillonite is investigated and it is found that Mg substitution increases the pKas of the neighboring tbnd Si-OH and tbnd Si-OH2 groups by 2-3 pKa units. Furthermore, our calculation shows that the pKa of edge tbnd Mg-(OH2)2 is as high as 13.2, indicating the protonated state dominates under common pH. Together with previous adsorption experiments, our derived acidity constants suggest that tbnd Si-O- and tbnd Al-(OH)2 groups are the most probable edge sites for complexing heavy metal cations.

  6. Coagulation processes of kaolinite and montmorillonite in calm, saline water

    Science.gov (United States)

    Zhang, Jin-Feng; Zhang, Qing-He; Maa, Jerome P.-Y.

    2018-03-01

    A three dimensional numerical model for simulating the coagulation processes of colloids has been performed by monitoring the time evolution of particle number concentration, the size distribution of aggregates, the averaged settling velocity, the collision frequency, and the collision efficiency in quiescent water with selected salinities. This model directly simulates all interaction forces between particles based on the lattice Boltzmann method (LBM) and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and thus, can reveal the collision and coagulation processes of colloidal suspensions. Although using perfect spherical particles in the modeling, the results were compared with those for kaolinite and montmorillonite suspensions to demonstrate the capability of simulating the responses of these particles with highly irregular shape. The averaged settling velocity of kaolinite aggregates in quiescent saline water reached a maximum of 0.16 mm/s when the salinity increasing to about 3, and then, exhibited little dependence on salinity thereafter. Model simulations results (by choosing specific values that represent kaolinite's characteristics) indicate a similar trend: rapid decrease of the particle number concentration (i.e., rapidly flocculated, and thus, settling velocity also increases rapidly) when salinity increases from 0 to 2, and then, only increased slightly when salinity was further increased from 5 to 20. The collision frequency for kaolinite only decreases slightly with increasing salinity because that the fluid density and viscosity increase slightly in sea water. It suggests that the collision efficiency for kaolinite rises rapidly at low salinities and levels off at high salinity. For montmorillonite, the settling velocity of aggregates in quiescent saline water continuedly increases to 0.022 mm/s over the whole salinity range 0-20, and the collision efficiency for montmorillonite rises with increasing salinities.

  7. Preparation of Polypropylene/Montmorillonite Nanocomposites Using Ionizing Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Güven, Olgun; Zengin, Fatma

    2011-07-01

    Polymer/clay nanocomposites are new generation materials that bring significant changes in mechanical, thermal and permeation properties of base polymers by low clay loading. In this study, polypropylene/montmorillonite nanocomposites were prepared by melt intercalation method by using batch type mixer. Two polypropylene samples with different melt flow indexes are used as the matrix, maleic anhydride grafted polypropylene (PP-g-MAH), and polypropylene granules oxidized by radiation/ozone are used as compatibilizer and unmodified clay (Na{sup +} montmorillonite, MMT) as the filler. Aim of this study is to examine the effect of different compatibilizers in the mechanical properties of polypropylene composite. Firstly, PP/clay samples were prepared and the effect of clay was examined, then 5, 10, 20kGy oxidized/degraded polypropylenes were used as compatibilizer and, 10 kGy was determined to be the most suitable irradiation dose for the best compatibilizing effect. Polypropylene granules were ozonated until they contained carbonyl groups equivalent to 10kGy oxidized PP, which was checked by FTIR-ATR spectroscopy. UV-visible reflectance measurements were also made on film samples and no significant changes were observed in visible region. Nano structures of some nanocomposites were characterized by PALS (Positron Annihilation Lifetime Spectroscopy) where it was observed that the addition of clay decreased the number of free volume holes and free volume hole radia. The dispersion state of MMT within polymer matrix was analyzed by XRD (X-ray diffraction). Tensile tests were made and the effect of the addition of clay and compatibilizers investigated. At low melt flow index PP, 1% MMT of PP/10kGyPP/MMT nanocomposite showed an increase in E-modulus 26% and in tensile strength 8% as compared to those of pristine PP. In conclusion radiation degraded (chain scissioned and oxidized) PP has been found to show very good compatibilizing effect for the natural montmorillonite

  8. Nanocomposites chitosan/montmorillonite for drug delivery system

    International Nuclear Information System (INIS)

    Braga, Carla R. Costa; Barbosa, Rossemberg C.; Lima, Rosemary S. Cunha; Fook, Marcus V. Lia; Silva, Suedina M. Lima

    2009-01-01

    In drugs delivery system the incorporation of an inorganic nanophase in polymer matrix, i.e. production of an inorganic-organic nanocomposite is an attractive alternative to obtain a constant release rate for a prolonged time. This study was performed to obtain films of nanocomposites Chitosan/montmorillonite intercalation by the technique of solution in the proportions of 1:1, 5:1 and 10:1. The nanocomposites were characterized by infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The results indicated that the feasibility of obtaining films of nanocomposites exfoliate. Among the suggested applications for films developed in this study includes them use for drugs delivery system. (author)

  9. Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiu-Wen, E-mail: wuxw2008@163.com [School of Science, China University of Geosciences, Beijing 100083 (China); National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083 (China); Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang [School of Science, China University of Geosciences, Beijing 100083 (China)

    2016-12-01

    Highlights: • Composite membranes are prepared with different montmorillonites and nafion solution. • Proton conductivities of the composite membranes are between 36.0 mS/cm and 38.5 mS/cm. • Ethanol permeability is between 0.69 × 10{sup −6} cm{sup 2}/s and 2.67 × 10{sup −6} cm{sup 2}/s. • Water uptake is approximately 24.30 mass%. - Abstract: The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10{sup −6} cm{sup 2}/s and 2.67 × 10{sup −6} cm{sup 2}/s.

  10. Heterogeneous reactions of dioctahedral smectites in illite-smectite and kaolinite-smectite mixed-layers: applications to clay materials for engineered barriers

    International Nuclear Information System (INIS)

    Meunier, A.; Proust, D.; Beaufort, D.; Lajudie, A.; Petit, J.-C.

    1992-01-01

    The clay materials selected for use in the engineered barriers of the French nuclear waste isolation programme are mainly composed of dioctahedral smectite, either bentonite of Wyoming type or kaolinite-smectites most often consist of randomly stacked layers with low and high charges. In the case of the Wyoming-type bentonite, these two differently charged layers do not react in the same way when subjected to hydrothermal alteration. Overall, the low-charge smectite layers react to form high-charge smectite layers + quartz + kaolinite. Then, fixing K ions, the high-charge smectite layers are transformed into illite-smectite mixed-layers (I/S) when the temperature conditions increase. A symmetrical process is observed in natural or experimental hydrothermal conditions when the high-charge smectite layers of I/S minerals react with quartz and/or kaolinite to produce low-charge smectite layers. The chemical properties of the bentonite-engineered barriers clearly depend on the low charge/high charge smectite layer proportion, which is in turn controlled by the temperature-dependent reactions in the vicinity of the waste disposal. Although there are fewer published data on the kaolinite-smectite mixed-layered minerals (K/S), a similar low charge-high charge reaction appears to affect their smectite component. The experimental alteration of K/S leads to the formation of a low-charge beidellite with an increase in the cation-exchange capacity and in the expandability of the clay material. Thus, the properties of the engineered barrier seems to be improved after hydrothermal alteration. (Author)

  11. Reactive barriers for 137Cs retention

    International Nuclear Information System (INIS)

    Krumhansl, James L.; Brady, Patrick V.; Anderson, Howard L.

    2000-01-01

    137 Cs was dispersed globally by cold war activities and, more recently, by the Chernobyl accident. Engineered extraction of 137 Cs from soils and groundwaters is exceedingly difficult. Because the half life of 137 Cs is only 30.2 years, remediation might be more effective (and less costly) if 137 Cs bioavailability could be demonstrably limited for even a few decades by use of a reactive barrier. Essentially permanent isolation must be demonstrated in those few settings where high nuclear level wastes contaminated the environment with 135 Cs (half life 2.3x10 6 years) in addition to 137 Cs. Clays are potentially a low-cost barrier to Cs movement, though their long-term effectiveness remains untested. To identify optimal clays for Cs retention Cs resorption was measured for five common clays: Wyoming Montmorillonite (SWy-1), Georgia Kaolinites (KGa-1 and KGa-2), Fithian Illite (F-Ill), and K-Metabentonite (K-Mbt). Exchange sites were pre-saturated with 0.16 M CsCl for 14 days and readily exchangeable Cs was removed by a series of LiNO 3 and LiCl washes. Washed clay were then placed into dialysis bags and the Cs release to the deionized water outside the bags measured. Release rates from 75 to 139 days for SWy-1, K-Mbt and F- 111 were similar; 0.017 to 0.021% sorbed Cs released per day. Both kaolinites released Cs more rapidly (0.12 to 0.05% of the sorbed Cs per day). In a second set of experiments, clays were doped for 110 days and subjected to an extreme and prolonged rinsing process. All the clays exhibited some capacity for irreversible Cs uptake so most soils have some limited ability to act as a natural barrier to Cs migration. However, the residual loading was greatest on K-Mbt (∼ 0.33 wt% Cs). Thus, this clay would be the optimal material for constructing artificial reactive barriers

  12. Hydraulic interaction of engineered and natural barriers. Task 8b-8d and 8f of SKB

    Energy Technology Data Exchange (ETDEWEB)

    Kroehn, Klaus-Peter

    2017-04-15

    The Task Force on Groundwater Flow and Transport of Solutes (TF GWFTS) and the Task Force on Engineered Barrier Systems (TF EBS) both established by the Svensk Kaernbraenslehantering AB (SKB) have defined the so-called Task 8 to investigate the hydraulic interaction of the granitic host rock at the Hard Rock Laboratory at Aespoeand the bentonite clay buffer in a deep geological repository. Task 8 a-d ran parallel to the related BRIE-project (Bentonite Rock Interaction Experiment) at the AespoeHard Rock Laboratory (HRL). The BRIE-project was concerned with an in-situ test where two boreholes were drilled from a tunnel floor and filled with compacted bentonite. Task 8 encompassed obviously characterizing the groundwater flow field as well as simulating bentonite re-saturation. Described here is an approach to solve the problem by decoupling both aspects. Groundwater flow was simplified to a steady-state single-phase flow model including discretely described large fractures. Modelling was performed with the code d{sup 3}f. Outflow data from the rock was then assigned to the inflow boundary of the alternative re-saturation model realized in the experimental code VIPER. With increasing knowledge about the site the upcoming data and the accompanying flow modelling indicated an inherent problem with predictions for the site and borehole characterization. Specific (deterministic) answers were sought from a flow domain that contains a relevant water-bearing fracture network which is only known in terms of geostatistics. While the overall flow regime could be represented in the final model the results were therefore not detailed below the scale of the boreholes. Early data from the flow model had indicated that water uptake of the bentonite at the bentonite-matrix contact would occur under restricted access to water. This had not been considered in laboratory tests up to then and also not in VIPER. A new appropriate boundary condition was developed and implemented. The time

  13. Modification of montmorillonite with alkyltrimethylammonium bromides. Effect of thermal and ultrasonic treatment upon the structure of montmorillonite

    International Nuclear Information System (INIS)

    Rodriguez M, F.J.; Galotto Lopez, M.J.; Guarda M, A.

    2009-01-01

    The aim of this work was synthesized organo clays using different methodologies oriented to improve the cationic interchange between montmorillonite and organic salts. Thermal and thermal-ultrasonic methods were studied. According to obtained results, the ultrasonic application improved the interchange between organic ammonium and sodium ion of the clay. On the other hand, an important effect of molecular weight of organic surfactant was observed. Formation of organo clays was evidenced through ray-X diffraction (RXD), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). (author)

  14. Combined effects of thermal barrier coating and blending with diesel fuel on usability of vegetable oils in diesel engines

    International Nuclear Information System (INIS)

    Aydin, Hüseyin

    2013-01-01

    The possibility of using pure vegetable oils in a thermally insulated diesel engine has been experimentally investigated. Initially, the standard diesel fuel was tested in the engine, as base experiment for comparison. Then the engine was thermally insulated by coating some parts of it, such as piston, exhaust and intake valves surfaces with zirconium oxide (ZrO 2 ). The main purpose of engine coating was to reduce heat rejection from the walls of combustion chamber and to increase thermal efficiency and thus to increase performance of the engine that using vegetable oil blends. Another aim of the study was to improve the usability of pure vegetable oils in diesel engines without performing any fuel treatments such as pyrolysis, emulsification and transesterification. Pure inedible cottonseed oil and sunflower oil were blended with diesel fuel. Blends and diesel fuel were then tested in the coated diesel engine. Experimental results proved that the main purpose of this study was achieved as the engine performance parameters such as power and torque were increased with simultaneous decrease in fuel consumption (bsfc). Furthermore, exhaust emission parameters such as CO, HC, and Smoke opacity were decreased. Also, sunflower oil blends presented better performance and emission parameters than cottonseed oil blends. -- Highlights: ► Usability of two different vegetable oils in a coated diesel engine was experimentally investigated. ► A diesel engine was coated with ZrO 2 layer to make the combustion chamber insulated. ► Test results showed significant improvements in performance parameters. ► While only minor reductions were observed in emissions with coated engine operation

  15. Bentonite erosion: effects on the long term performance of the engineered barrier and radionuclide transport - The BELBAR project

    International Nuclear Information System (INIS)

    Sellin, P.; Sundman, D.; Bailey, L.; Missana, T.; Schaefer, T.; Cervinka, R.; Koskinen, K.

    2012-01-01

    Document available in extended abstract form only. BELBaR is a Collaborative Project within the Seventh Framework Programme of the European Atomic Energy Community (Euratom) for nuclear research and training activities. The main aim of BELBaR is to increase knowledge of the processes that control clay colloid stability, generation and its ability to transport radionuclides. The overall purpose of the project is to come up with a new way of treating issues in long-term safety/performance assessment. The project started March 1, 2012 and has a duration of 48 months. The project has 14 partners from seven European countries. The main aim of BELBaR is to reduce the uncertainties in the description of the effect of clay colloids on the long term performance of the engineered barrier and on radionuclide transport as illustrated in Figure 1. This is done by: - Improving the understanding on when bentonite colloids are unstable. For a given site/site evolution, this is critical information, since it determines whether or not clay colloids need to be included in the long-term assessment. - Improving the quantitative models for erosion on the bentonite barrier for the cases when the colloids are stable - Improving the understanding of how radionuclides attach to clay colloids. This information will be used to formulate improved transport models for the assessment of radionuclide transport in the geosphere. To meet the main aim a number of experimental and modelling activities will be undertaken within the project. BELBaR consists of six RTD (research and technical development) work packages and one project management work package. WP1 will have the responsibility to ensure that that the type and values of the parameters selected for experimental and modelling work are those that represent as much as possible the full range of conditions and situations that can be expected in a repository. Drawing on the work undertaken in WP 2 to 5, the general objective of this work package

  16. A mathematical model for the performance assessment of engineering barriers of a typical near surface radioactive waste disposal facility

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, Raphaela N.; Rotunno Filho, Otto C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Lab. de Hidrologia e Estudos do Meio Ambiente]. E-mail: otto@hidro.ufrj.br; Ruperti Junior, Nerbe J.; Lavalle Filho, Paulo F. Heilbron [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)]. E-mail: nruperti@cnen.gov.br

    2005-07-01

    This work proposes a mathematical model for the performance assessment of a typical radioactive waste disposal facility based on the consideration of a multiple barrier concept. The Generalized Integral Transform Technique is employed to solve the Advection-Dispersion mass transfer equation under the assumption of saturated one-dimensional flow, to obtain solute concentrations at given times and locations within the medium. A test-case is chosen in order to illustrate the performance assessment of several configurations of a multi barrier system adopted for the containment of sand contaminated with Ra-226 within a trench. (author)

  17. A mathematical model for the performance assessment of engineering barriers of a typical near surface radioactive waste disposal facility

    International Nuclear Information System (INIS)

    Antonio, Raphaela N.; Rotunno Filho, Otto C.

    2005-01-01

    This work proposes a mathematical model for the performance assessment of a typical radioactive waste disposal facility based on the consideration of a multiple barrier concept. The Generalized Integral Transform Technique is employed to solve the Advection-Dispersion mass transfer equation under the assumption of saturated one-dimensional flow, to obtain solute concentrations at given times and locations within the medium. A test-case is chosen in order to illustrate the performance assessment of several configurations of a multi barrier system adopted for the containment of sand contaminated with Ra-226 within a trench. (author)

  18. Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells

    OpenAIRE

    Fangming Jin; Zisheng Su; Bei Chu; Pengfei Cheng; Junbo Wang; Haifeng Zhao; Yuan Gao; Xingwu Yan; Wenlian Li

    2016-01-01

    In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59?mA/cm2, an open-circuit voltage (Voc) of 1.06?V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5?G solar illumination at 100?mW/cm2. Device performance was substantiall...

  19. Controlled swelling and adsorption properties of polyacrylate/montmorillonite composites

    Energy Technology Data Exchange (ETDEWEB)

    Natkanski, Piotr [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Kustrowski, Piotr, E-mail: kustrows@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Bialas, Anna; Piwowarska, Zofia [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Michalik, Marek [Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, 30-063 Krakow (Poland)

    2012-10-15

    A series of novel polyacrylate/montmorillonite composites was synthesized by in situ polymerization in aqueous slurry of clay. Dissociated (obtained by adding ammonium or sodium hydroxide) and undissociated forms of acrylic acid were used as monomers in the hydrogel synthesis. The structure and composition of the samples were studied by powder X-ray diffraction, diffuse reflectance infra-red Fourier transform spectroscopy, thermogravimetry and elemental analysis. It has been found that the kind of monomer influences strongly the location of a polymer chain in the formed composite. Complete intercalation of hydrogel into the interlayer space of montmorillonite was observed for sodium polyacrylate, whereas polyacrylic acid and ammonium polyacrylate mainly occupied the outer surface of the clay. The position of hydrogel determined the swelling and adsorption properties of the studied composites. The important factor influencing the kinetics of Fe(III) cation adsorption was pH. The analysis of adsorption isotherms allowed to propose the mechanism of Fe(III) cation adsorption. Highlights: Black-Right-Pointing-Pointer Polyacrylate hydrogels can be introduced into the interlayers of clay. Black-Right-Pointing-Pointer The position of hydrogel in the composite depends on the polymer type. Black-Right-Pointing-Pointer Ammonium polyacrylate places outside the clay, sodium one is intercalated into it. Black-Right-Pointing-Pointer Swelling and adsorption capacities can be controlled by the polymer position. Black-Right-Pointing-Pointer High adsorption efficiency in Fe(III) removal was observed.

  20. Preparation and characterization of nano gold supported over montmorillonite clays

    International Nuclear Information System (INIS)

    Suraja, P.V.; Binitha, N.N.; Yaakob, Z.; Silija, P.P.

    2009-01-01

    Full text: The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl 4 ·3H 2 O by deposition-precipitation (DP) methods. However, it is difficult to prepare nano scale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. Here there is no need of increasing the pH of the solution to reduce the Au 3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-Vis Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method. (author)

  1. QINS studies of water diffusion in Na-Montmorillonite

    International Nuclear Information System (INIS)

    Gay-Duchosal, M.

    1999-01-01

    Complete text of publication follows. The rotational and translational motion of interlayer water was investigated in Na-Montmorillonite as a function of the humidity (one-, two- and three-layers). Partially orientated samples produced by deposition onto a filter under pressure were used. Measurements were made at two different resolutions 120 μeV and 36 μeV. In order to observe the anisotropy, measurements with sample orientations of 135 and 45 degree were made with respect to the incident beam corresponding to Q-parallel and Q-perpendicular to the clay layers. The fitting procedure consists of an elastic term based on a fit to an analogous D 2 O hydrated sample and a quasielastic term containing both rotational and translational contributions (1). At low resolution with Q-parallel a rotational broadening was observed that increases, indicating increasing water mobility, as the water content and hence the layer spacing increases. For the three-layer hydrate with the two different orientations the broadening is the same showing no measurable anisotropy of the rotational motion. At high resolution an additional broadening was seen due to translational diffusion of a similar magnitude to that measured previously for Li-Montmorillonite (2). We are currently refining our data analysis in order to determine whether the anisotropy of the translational motion with respect to the orientation of the clay is measurable. (author)

  2. Preparation and Characterization of Nano Gold Supported over Montmorillonite Clays

    Energy Technology Data Exchange (ETDEWEB)

    Suraja, P V; Binitha, N N; Yaakob, Z; Silija, P P, E-mail: binithann@yahoo.co.in [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2011-02-15

    The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl4{center_dot}3H2O by deposition-precipitation (DP) methods. However, it is difficult to prepare nanoscale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. There is no need of increasing the pH of the solution to reduce the Au3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-VIS Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method.

  3. Characterization of polyurethane/organophilic montmorillonite nanocomposites by low field NMR

    International Nuclear Information System (INIS)

    Silva, Marcos Anacleto da; Tavares, Maria I.B.; Nascimento, Suelen A.M.; Rodrigues, Elton J. da R

    2012-01-01

    Polyurethanes are important and versatile materials, mainly due to some of their properties, such as high resistance to abrasion and tearing, excellent absorption of mechanical shocks and good flexibility and elasticity. However, they have some drawbacks as well, such as low thermal stability and barrier properties. To overcome these disadvantages, various studies have been conducted involving organophilic polyurethane/montmorillonite nanocomposites. The investigation of the structure of polyurethane/clay nanocomposites has mainly been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay nanocomposite films obtained by solution intercalation were studied. The nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (LF-NMR). The LF-NMR measurements, with determination of the spin-lattice relaxation time of the hydrogen nucleus, supplied important information about the molecular dynamics of these nanocomposites. The X-ray diffraction measurements validated the results found by NMR. The thermal stability of the material was also determined by thermogravimetric analysis (TGA) under an inert atmosphere. A slight improvement in this stability was observed in the nanocomposite in comparison with polyurethane (author)

  4. Effect of seawater on consistency, infiltration rate and swelling characteristics of montmorillonite clay

    Directory of Open Access Journals (Sweden)

    Mohie Eldin Elmashad

    2016-08-01

    Full Text Available This paper presents the results of an experimental investigation performed to quantify the effect of mixing clayey soils with saltwater on consistency and swelling characteristics of clays. Massive natural clay deposits and compacted clay backfills either exist or are used in certain important and sensitive applications such as dams, liners, barriers and buffers in waste disposal facilities. In many cases, the clay deposits in these applications are subjected to saltwater. However, in standard laboratory classification tests, distilled or potable water are usually used in mixing test samples. This may lead to faulty interpretation of the actual in-situ consistency and volume change behaviors. In this research, an attempt is made to quantify the changes in consistency and swelling of clay soils from various locations around the Nile valley and possessing a wide range of consistency, when mixed with natural seawater with different salt concentrations. The results showed that the increase of the salt concentration of the mixing water may result in major decrease in the liquid limit and swelling characteristics of high plasticity montmorillonite clays. The reduction in the swelling of the clay soils is also proportional to the rate of saltwater infiltration. In an attempt to correlate the swelling of clays to the rate of water infiltration, a new simplified laboratory apparatus is proposed where swelling and infiltration are measured in one simple test “the swelling infiltrometer”.

  5. Fabrication and Characterization of Cellulose Acetate/Montmorillonite Composite Nanofibers by Electrospinning

    Directory of Open Access Journals (Sweden)

    Se Wook Kim

    2015-01-01

    Full Text Available Nanofibers composed of cellulose acetate (CA and montmorillonite (MMT were prepared by electrospinning method. MMT was first dispersed in water and mixed with an acetic acid solution of CA. The viscosity and conductivity of the CA/MMT solutions with different MMT contents were measured to compare with those of the CA solution. The CA/MMT solutions were electrospun to fabricate the CA/MMT composite nanofibers. The morphology, thermal stability, and crystalline and mechanical properties of the composite nanofibers were characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, energy dispersive X-ray spectroscopy (EDX, thermogravimetric analysis (TGA, X-ray diffraction (XRD, and tensile test. The average diameters of the CA/MMT composite nanofibers obtained by electrospinning 18 wt% CA/MMT solutions in a mixed acetic acid/water (75/25, w/w solvent ranged from 150~350 nm. The nanofiber diameter decreased with increasing MMT content. TEM indicated the coexistence of CA nanofibers. The CA/MMT composite nanofibers showed improved tensile strength compared to the CA nanofiber due to the physical protective barriers of the silicate clay layers. MMT could be incorporated into the CA nanofibers resulting in about 400% improvement in tensile strength for the CA sample containing 5 wt% MMT.

  6. Nanocomposites of rice and banana flours blend with montmorillonite: partial characterization.

    Science.gov (United States)

    Rodríguez-Marín, María L; Bello-Pérez, Luis A; Yee-Madeira, Hernani; Zhong, Qixin; González-Soto, Rosalía A

    2013-10-01

    Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Barrier layer engineering: Performance evaluation of E-mode InGaN/AlGaN/GaN HEMT

    Science.gov (United States)

    Majumdar, Shubhankar; Das, S.; Biswas, D.

    2015-08-01

    Impact on DC characteristics of InGaN/AlGaN/GaN HEMT due to variation in the hetero-structure parameters i.e. molar fraction of Al and thickness of AlGaN barrier layer is presented in this paper. Gate controllability over the channel is dependent on barrier layer thickness, and molar fraction has an impact on band offset and 2DEG, which further affects the current. HEMT device that is simulated in SILVACO has InGaN cap layer of 2 nm thickness with 15% In molar fraction, variation of Al percentage and thickness of the AlGaN barrier layer are taken as 15-45% and 5-20nm, respectively. A tremendous change in threshold voltage (Vth), maximum transconductance (Gmmax) and subthreshold swing is found due to variation in hetero-structure parameter of barrier layer and the values are typically 1.3-0.1 V, 0.6-0.44 S/mm and 75-135 mV/dec respectively.

  8. Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite.

    Science.gov (United States)

    Kumar, P; Sandeep, K P; Alavi, S; Truong, V D; Gorga, R E

    2010-06-01

    The nonbiodegradable and nonrenewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified montmorillonite (MMT) were prepared using melt extrusion. The effect of different type (Cloisite 20A and Cloisite 30B) and content (0% to 15%) of modified MMT on the structure (degree of intercalation and exfoliation) and properties (color, mechanical, dynamic mechanical, thermal stability, and water vapor permeability) of SPI-MMT bio-nanocomposite films were investigated. Extrusion of SPI and modified MMTs resulted in bio-nanocomposites with exfoliated structures at lower MMT content (5%). At higher MMT content (15%), the structure of bio-nanocomposites ranged from intercalated for Cloisite 20A to disordered intercalated for Cloisite 30B. At an MMT content of 5%, bio-nanocomposite films based on modified MMTs (Cloisite 20A and Cloisite 30B) had better mechanical (tensile strength and percent elongation at break), dynamic mechanical (glass transition temperature and storage modulus), and water barrier properties as compared to those based on natural MMT (Cloisite Na(+)). Bio-nanocomposite films based on 10% Cloisite 30B had mechanical properties comparable to those of some of the plastics that are currently used in food packaging applications. However, much higher WVP values of these films as compared to those of existing plastics might limit the application of these films to packaging of high moisture foods such as fresh fruits and vegetables.

  9. Collection of measurement data from in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory. FY2014

    International Nuclear Information System (INIS)

    Nakayama, Masashi; Ohno, Hirokazu; Nakayama, Mariko; Kobayashi, Masato

    2015-09-01

    The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, “Geoscientific Research” and “Research and Development on Geological Disposal Technologies”, and proceeds in three overlapping phases, “Phase I: Surface-based investigations”, “Phase II: Investigations during tunnel excavation” and “Phase III: Investigations in the underground facilities”, over a period of around 20 years. Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at G.L.-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal – Hydrological – Mechanical – Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the EBS experiment from December, 2014 to March, 2015. The summarized data of the EBS experiment will be published periodically. A CD-ROM is attached as an appendix. (J.P.N)

  10. Collection of measurement data from in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory. FY2015

    International Nuclear Information System (INIS)

    Nakayama, Masashi; Ohno, Hirokazu; Nakayama, Mariko; Kobayashi, Masato

    2016-07-01

    The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, 'Geoscientific Research' and 'Research and Development on Geological Disposal Technologies', and proceeds in three overlapping phases, 'Phase I: Surface-based investigations', 'Phase II: Investigations during tunnel excavation' and 'Phase III: Investigations in the underground facilities', over a period of around 20 years. Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at G.L.-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal - Hydrological - Mechanical - Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the EBS experiment from December, 2014 to March, 2016. The summarized data of the EBS experiment will be published periodically. A CD-ROM is attached as an appendix. (J.P.N)

  11. Osmotic pressure in Ca/Na montmorillonite dispersions: Monte Carlo simulations

    International Nuclear Information System (INIS)

    Joensson, Bo; Aakesson, T.; Segad, M.; Cabane, B.

    2010-01-01

    Document available in extended abstract form only. In the past, clay-water systems have been extensively studied. due to its importance in agricultural as well as technological applications. A more recent use of clay is as sealing material for nuclear waste. The success for such a containment depends on the clay structure and its swelling properties. This means that the clay should be able to sustain considerable changes in the surrounding ground water including salinities of glacial melt water as well as sea water, while still being an effective hydraulic barrier. We have approached this problem using statistical mechanical simulation techniques. The osmotic pressure in Ca/Na montmorillonite dispersions has been calculated via Monte Carlo simulations. For a clay system in equilibrium with pure water, Monte Carlo simulations predict a large swelling when the clay counterions are monovalent, while in presence of divalent counterions a limited swelling is predicted with an aqueous layer between the clay lamellae of about 1 nm - in excellent agreement with SAXS data. Montmorillonite in contact with a salt reservoir with e.g. both Na and Ca counterions will only show a modest swelling unless the Na + concentration in the bulk is several orders of magnitude larger than the Ca 2+ concentration. This is true both for a clay repository surrounded by ground water as well as sea water of high salinity. The limited swelling of clay in presence of divalent counterions is a consequence of ion-ion correlations, which both reduce the entropic repulsion and give rise to an attractive component in the total osmotic pressure. Ion-ion correlations also favour divalent counterions when competing with monovalent ones. This is an important aspect for the retention of radioactive charged species. A more fundamental result of ion-ion correlations is that the osmotic pressure as a function of clay sheet separation becomes non-monotonic - which indicates the possibility of a phase

  12. A study of the fixing of phosphoric ions by zirconium-montmorillonite; Etude de la fixation d'ions phosphoriques par la montmorillonite-zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Bittel, R; Boursat, C; Platzer, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    In connection with the research carried out on the purification of nuclear reactor water, we have undertaken a study of the ion-exchange properties of acid montmorillonite. In a previous paper, we described the preparation of zirconium-montmorillonite small plate. The present article aims to study some of the properties of the clay obtained. We have observed that zirconium-montmorillonite fixes very strongly the phosphorus from solutions of phosphoric acid or of phosphates: on 1 g of clay it is possible to fix 1,2 milli-atoms-gram of zirconium and the zirconium montmorillonite itself fixes 2,1 milli-atoms-gram of phosphorus. An explanation of these experimental results, which is as much chemical as mineralogical, is the hypothesis that the fixing of phosphoric ions modifies the distribution of the ions between the platelets and precipitates a very slightly soluble product of the type diphospho-zirconic acid. (author) [French] En rapport avec des recherches sur I'epuration de l'eau des reacteurs nucleaires nous avons entrepris une etude sur les proprietes d'echangeur d'ions de la montmorillonite-acide. Dans une precedente publication, nous avons decrit la preparation des plaquettes de montmorillonite-zirconium. La presente communication a pour but d'etudier quelques proprietes de l'argile obtenue. Nous avons constate que la montmorilionite-zirconium fixe le phosphore de solutions d'acide phosphorique ou de phosphate avec une grande intensite: sur 1 g d'argile, on peut fixer 1,2 atomes-gramme de zirconium, et la montmorillonite-zirconium fixe a son tour 2,1 milli-atomesgramme de phosphore. Une explication des resultats experimentaux, tant d'ordre chimique que d'ordre mineralogique, consiste en l'hypothese suivant laquelle la fixation d'ions phosphoriques modifierait la repartition des ions entre les feuillets avec precipitation du compose tres peu soluble (type: acide diphosphozirconique). (auteur)

  13. Synthesis of Poly aniline-Montmorillonite Nano composites Using H2O2 as the Oxidant

    International Nuclear Information System (INIS)

    Binitha, N.; Binitha, N.; Suraja, V.; Zahira Yaakob; Sugunan, S.

    2011-01-01

    Poly aniline montmorillonite nano composite was prepared using H 2 O 2 as the oxidant. The catalytic environment of montmorillonite favours polymerization. Intercalation and composite formation was proven from various techniques such as XRD, FTIR, DRS and thermal analysis. XRD patterns give the dimension of the intercalated PANI, from the shift of 2θ values, which is in the nano range. FTIR showed that PANI composite formation occurred without affecting the basic clay layer structure. Thus the successful development of an alternative cheap route for poly aniline-montmorillonite nano composite was well established. (author)

  14. Characterization of synthesized polyurethane/montmorillonite nanocomposites foams

    International Nuclear Information System (INIS)

    Ansari, Farahnaz; Njuguna, James; Sachse, Sophia; Kavosh, Masoud; Michalowski, S; Pielichowski, Krzysztof

    2014-01-01

    Nanophased hybrid composites based on polyurethane/montmorillonite (PU/MMT) have been fabricated. The nanocomposite which was formed by the addition of a polyol premix with 4,4'-diphenylmethane diisocyanate to obtain nanophased polyurethane foams which were then used for fabrication of nanocomposite panels has been shown to have raised strength, stiffness and thermal insulation properties. The nanophased polyurethane foam was characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM) measurements and X-ray diffraction (XRD). TEM and SEM analysis indicated that nanophased particles are dispersed homogeneously in the polyurethane matrix on the nanometer scale indicating that PU/MMT is an intercalated nanocomposite with a 2-3 nm nanolayer thickness

  15. Molecular dynamics simulation of polyacrylamides in potassium montmorillonite clay hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Junfang [CSIRO Petroleum Resources, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168 (Australia); Rivero, Mayela [CSIRO Petroleum, PO Box 1130, Bentley, Western Australia, 6102 (Australia); Choi, S K [CSIRO Petroleum Resources, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168 (Australia)

    2007-02-14

    We present molecular dynamics simulation results for polyacrylamide in potassium montmorillonite clay-aqueous systems. Interlayer molecular structure and dynamics properties are investigated. The number density profile, radial distribution function, root-mean-square deviation (RMSD), mean-square displacement (MSD) and diffusion coefficient are reported. The calculations are conducted in constant NVT ensembles, at T = 300 K and with layer spacing of 40 A. Our simulation results showed that polyacrylamides had little impact on the structure of interlayer water. Density profiles and radial distribution function indicated that hydration shells were formed. In the presence of polyacrylamides more potassium counterions move close to the clay surface while water molecules move away, indicating that potassium counterions are hydrated to a lesser extent than the system in which no polyacrylamides were added. The diffusion coefficients for potassium and water decreased when polyacrylamides were added.

  16. Samarium ion exchanged montmorillonite for high temperature cumene cracking reaction

    International Nuclear Information System (INIS)

    Binitha, N.N.

    2009-01-01

    Full text: Nano material Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using TPD of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Bronsted acidity is confirmed from high selectivity to benzene. (author)

  17. Genotoxicity of unmodified and organo-modified montmorillonite

    DEFF Research Database (Denmark)

    Sharma, Anoop Kumar; Schmidt, Bjørn; Frandsen, Henrik Lauritz

    2010-01-01

    absent in the filtered samples, which was independently confirmed by dynamic light-scattering measurements. Detection and identification of free quaternary ammonium modifier in the filtered sample was carried out by HPLC-Q-TOF/MS and revealed a total concentration of a mixture of quaternary ammonium...... assay, none of the clays produced ROS in a cell-free test system (the DCFH-DA assay). Inductively coupled plasma mass-spectrometry (ICP-MS) was used to detect clay particles in the filtered samples using aluminium as a tracer element characteristic to clay. The results indicated that clay particles were...... analogues of 1.57 mu g/ml. These findings suggest that the genotoxicity of organo-modified montmorillonite was caused by the organo-modifier. The detected organo-modifier mixture was synthesized and comet-assay results showed that the genotoxic potency of this synthesized organo-modifier was in the same...

  18. Montmorillonite based artificial nacre prepared via a drying process

    International Nuclear Information System (INIS)

    Bennadji-Gridi, Fayza; Smith, Agnes; Bonnet, Jean-Pierre

    2006-01-01

    Taking advantage of the specific behaviour of Na/Ca montmorillonite in aqueous dispersion, textured films were prepared by progressive evaporation of dispersions with low concentrations of delaminated platelets. The increase of the concentration of ions during evaporation changes the nature of the clay mineral platelet face interactions from repulsive to attractive. After complete drying, a dense brick-like structure is obtained when a sodium salt is used as deflocculant. The bending strength of the textured film is strongly affected by cracks formation during drying, specially when the sample thickness increases. After optimisation, crack-free textured samples with a 140 μm thickness, 20 cm x 25 cm area and 120 MPa bending strength were obtained

  19. Mechanism of amitriptyline adsorption on Ca-montmorillonite (SAz-2)

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Po-Hsiang [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Geosciences, University of Wisconsin – Parkside, 900 Wood Road, Kenosha, WI 53144 (United States); Kuo, Chung-Yih [Department of Public Health, College of Health Care and Management, Chung Shan Medical University, No. 110, Sec. 1, Chien-kuo N Road, Taichung 40242, Taiwan (China); Jean, Jiin-Shuh [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Chen, Wan-Ru [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Lv, Guocheng [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China)

    2014-07-30

    Graphical abstract: XRD patterns to show AMI intercalation into SAz-2 vs. direct mixing of the same amount of AMI with SAz-2. - Highlights: • Ca-montmorillonite is proven to be an efficient adsorbent or sink for amitriptyline. • The high adsorption capacity is accompanied with intercalation into interlayers. • The adsorption is mainly governed by a cation exchange mechanism. • Horizontal mono- and bi-layer conformations occur at low and high adsorption levels. • The process is an endothermic physisorption at high adsorption levels. - Abstract: The uptake of amitriptyline (AMI) from aqueous environment by Ca-montmorillonite (SAz-2) was studied in a batch system under different physicochemical conditions. The adsorbent was characterized by X-ray diffraction and Fourier transform infrared (FTIR) analyses. The AMI adsorption on SAz-2 obeyed the Langmuir isotherm with a capacity of 330 mg/g (1.05 mmol/g) at pH 6–7. The adsorption kinetics was fast, almost reaching equilibrium in 2 h, and followed a pseudo-second-order kinetic model. Desorption of exchangeable cations correlated with the AMI adsorption well, indicating that cation exchange was the major mechanism. X-ray diffraction patterns showing significant expansions of the d{sub 0} {sub 0} {sub 1} spacing and characteristic FTIR band shifts toward higher frequencies after AMI adsorption onto SAz-2 indicated that the adsorbed AMI molecules were intercalated into the interlayers of the mineral. Thermodynamic parameters based on partitioning coefficients suggested that the AMI adsorption was an endothermic physisorption at high adsorption levels. At low and higher AMI adsorption levels, the intercalated AMI molecules take a horizontal monolayer and bilayer conformation, respectively. The higher adsorption capacity suggested that SAz-2 could be a good candidate to remove AMI from wastewater and would be an important environmental sink for the fate and transport of AMI in soils and groundwater.

  20. Interstratified Illite/Montmorillonite in Kamojang Geothermal Field, Indonesia

    Directory of Open Access Journals (Sweden)

    D. F. Yudiantoro

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i4.167Kamojang geothermal field located in West Java Province, falls under the Pangkalan Subregency, Bandung Regency. The researched area is a geothermal field located in the Quaternary volcanic caldera system of about 0.452 to 1.2 Ma. The volcanic activity generated hydrothermal fluids, interacting with rocks producing mineral alteration. The minerals formed in the areas of research are interstratified illite/montmorillonite (I/M. Analyses to identify interstratified I/M have been performed by X-ray diffraction using ethylene glycol, while the determination of the type and percentage of interstratified I/M was based on the calculation method of Watanabe. The methodology was applied on core and cutting samples from Wells KMJ-8, 9, 11, 13, 16, 23, 49, 51, and 54. The result of analysis of the samples shows that the type of clay is interstratified illite/montmorillonite and the minerals are formed at temperatures ranging from 180 to 220° C. The type of interstratified I/M in the studied area is S = 0 and S = 1. The percentage of illite type S = 0 is between 20 - 35% illite, whereas type S = 1 has about 45 - 72% illite. Along with the increasing depth, the percentage of illite is getting greater. This is consistent with the vertical distribution of temperature which increases according to the depth. This correlation results in an interpretation that the upflow zone of the geothermal reservoir is located in the centre of the Kamojang geothermal field.

  1. Mechanism of amitriptyline adsorption on Ca-montmorillonite (SAz-2)

    International Nuclear Information System (INIS)

    Chang, Po-Hsiang; Jiang, Wei-Teh; Li, Zhaohui; Kuo, Chung-Yih; Jean, Jiin-Shuh; Chen, Wan-Ru; Lv, Guocheng

    2014-01-01

    Graphical abstract: XRD patterns to show AMI intercalation into SAz-2 vs. direct mixing of the same amount of AMI with SAz-2. - Highlights: • Ca-montmorillonite is proven to be an efficient adsorbent or sink for amitriptyline. • The high adsorption capacity is accompanied with intercalation into interlayers. • The adsorption is mainly governed by a cation exchange mechanism. • Horizontal mono- and bi-layer conformations occur at low and high adsorption levels. • The process is an endothermic physisorption at high adsorption levels. - Abstract: The uptake of amitriptyline (AMI) from aqueous environment by Ca-montmorillonite (SAz-2) was studied in a batch system under different physicochemical conditions. The adsorbent was characterized by X-ray diffraction and Fourier transform infrared (FTIR) analyses. The AMI adsorption on SAz-2 obeyed the Langmuir isotherm with a capacity of 330 mg/g (1.05 mmol/g) at pH 6–7. The adsorption kinetics was fast, almost reaching equilibrium in 2 h, and followed a pseudo-second-order kinetic model. Desorption of exchangeable cations correlated with the AMI adsorption well, indicating that cation exchange was the major mechanism. X-ray diffraction patterns showing significant expansions of the d 0 0 1 spacing and characteristic FTIR band shifts toward higher frequencies after AMI adsorption onto SAz-2 indicated that the adsorbed AMI molecules were intercalated into the interlayers of the mineral. Thermodynamic parameters based on partitioning coefficients suggested that the AMI adsorption was an endothermic physisorption at high adsorption levels. At low and higher AMI adsorption levels, the intercalated AMI molecules take a horizontal monolayer and bilayer conformation, respectively. The higher adsorption capacity suggested that SAz-2 could be a good candidate to remove AMI from wastewater and would be an important environmental sink for the fate and transport of AMI in soils and groundwater

  2. Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior

    Directory of Open Access Journals (Sweden)

    Shameli K

    2011-03-01

    Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Mohsen Zargar2, Wan Md Zin Wan Yunus1, Abdolhossein Rustaiyan3, Nor Azowa Ibrahim11Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Department of Biology, Faculty of Science, Islamic Azad University, Qom Branch, Qom, Iran; 3Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IranAbstract: Silver nanoparticles (Ag NPs were synthesized by the chemical reducing method in the external and interlamellar space of montmorillonite (MMT as a solid support at room temperature. AgNO3 and NaBH4 were used as a silver precursor and reducing agent, respectively. The most favorable experimental conditions for synthesizing Ag NPs in the MMT are described in terms of the initial concentration of AgNO3. The interlamellar space limits changed little (d-spacing = 1.24–1.47 nm; therefore, Ag NPs formed on the MMT suspension with d-average = 4.19–8.53 nm diameter. The Ag/MMT nanocomposites (NCs, formed from AgNO3/MMT suspension, were characterizations with different instruments, for example UV-visible, PXRD, TEM, SEM, EDXRF, FT-IR, and ICP-OES analyzer. The antibacterial activity of different sizes of Ag NPs in MMT were investigated against Gram-positive, ie, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA and Gram-negative bacteria, ie, Escherichia coli, Escherichia coli O157:H7, and Klebsiella pneumoniae, by the disk diffusion method using Mueller-Hinton agar (MHA. The smaller Ag NPs were found to have significantly higher antibacterial activity. These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications.Keywords: silver nanoparticles, nanoparticles, montmorillonite, antibacterial activity, Mueller-Hinton agar 

  3. Exhaust purification of DI spark ignition engines by means of barrier discharge. Final report; Abgasreinigung von DI-Ottomotoren durch Barrierenentladungen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Wolters, P.; Lepperhoff, G.; Baumgarten, H.; Scharr, D.; Neff, W.; Trompeter, F.J.; Seiwert, S.; Kamp, J.; Pochner, K.

    2000-07-01

    Dielectric barrier discharge offers the advantage to excite and dissociate molecules in the exhaust gas stream. Those dissociated and excited species are oxidizing or reducing harmful exhaust gas components. The advantage of a plasma chemical system in comparison to a catalytic converter is the instantaneous activity at ambient temperature from the turn key of the engine. The investigations presented here focus on the plasma chemical oxidation of hydrocarbons in the exhaust gas stream during cold start conditions. The article concerns the design and development of a plasma system in order to decrease the hydrocarbon emissions from engine start till catalyst light off. Vehicle results in the new European driving cycle show a hydrocarbon conversion of more than 43% in the first 11 seconds from engine start. In this period nearly all types of hydrocarbon were reduced. The exhaust back pressure of the sytem is comparable to the conventional muffler. Further system improvement can be achieved by an optimization of the disk electrode design. [German] Um die strengen zukuenftigen Schadstoffemissionsgrenzwerte von Ottomotoren in der EU oder den USA einhalten zu koennen, werden derzeit weltweit auch plasmachemische Methoden zur Abgasnachbehandlung in Betracht gezogen. Insbesondere nichtthermische Atmosphaerendruck-Gasentladungen, wie die Barrierenentladung, zeigen Chancen auf, die Betriebsbedingungen und Grenzen gegenwaertiger katalytischer Techniken zu erweitern. In diesem Vorhaben wurde die Barrierenentladung zur plasmachemischen Umsetzung von Schadstoffen im Abgas eines mager betriebenen Ottomotors im Serienautomobil untersucht, um das Potential zur Abgasreinigung zu bewerten und auszuweiten. (orig.)

  4. Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions

    International Nuclear Information System (INIS)

    Samanta, Archana; Takkar, Sonam; Kulshreshtha, Ritu; Nandan, Bhanu; Srivastava, Rajiv K.

    2016-01-01

    The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. - Highlights: • Tenside free, clay stabilized Pickering emulsion of PCL is made with minimal organic solvent. • Organic–inorganic composite fibrous matrices were produced via emulsion electrospinning. • Fiber fineness was efficiently controlled by variation in emulsion formulation. • Fibrous matrices of high tensile strength and modulus were obtained in comparison to neat PCL matrix. • PCL/clay matrices showed effective cell proliferation as a neat PCL matrix.

  5. Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions.

    Science.gov (United States)

    Samanta, Archana; Takkar, Sonam; Kulshreshtha, Ritu; Nandan, Bhanu; Srivastava, Rajiv K

    2016-12-01

    The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Archana [Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Takkar, Sonam; Kulshreshtha, Ritu [Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Nandan, Bhanu [Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Srivastava, Rajiv K., E-mail: rajiv@textile.iitd.ac.in [Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

    2016-12-01

    The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. - Highlights: • Tenside free, clay stabilized Pickering emulsion of PCL is made with minimal organic solvent. • Organic–inorganic composite fibrous matrices were produced via emulsion electrospinning. • Fiber fineness was efficiently controlled by variation in emulsion formulation. • Fibrous matrices of high tensile strength and modulus were obtained in comparison to neat PCL matrix. • PCL/clay matrices showed effective cell proliferation as a neat PCL matrix.

  7. Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite as a potential adsorbent for Cr (VI) removal

    CSIR Research Space (South Africa)

    Setshedi, KZ

    2013-01-01

    Full Text Available Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite (PPy OMMT NC), was prepared as a potential adsorbent, via in situ polymerization of pyrrole monomer for adsorption of toxic Cr(VI) from aqueous solution. The WAXD...

  8. Mössbauer study of pH dependence of iron-intercalation in montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E., E-mail: kuzmann@caesar.elte.hu [Eötvös Loránd University, Institute of Chemistry (Hungary); Garg, V. K.; Singh, H.; Oliveira, A. C. de; Pati, S. S. [University of Brasília, Institute of Physics (Brazil); Homonnay, Z.; Rudolf, M. [Eötvös Loránd University, Institute of Chemistry (Hungary); Molnár, Á. M.; Kovács, E. M. [University of Debrecen, Imre Lajos Isotope Laboratory, Department of Colloid and Environmental Chemistry (Hungary); Baranyai, E. [University of Debrecen, Department of Inorganic and Analytical Chemistry (Hungary); Kubuki, S. [Tokyo Metropolitan University, Department of Chemistry (Japan); Nagy, N. M.; Kónya, J. [University of Debrecen, Imre Lajos Isotope Laboratory, Department of Colloid and Environmental Chemistry (Hungary)

    2016-12-15

    {sup 57}Fe Mössbauer spectroscopy and XRD have successfully been applied to show the incorporation of Fe ion into the interlayer space of montmorillonite via treatment with FeCl {sub 3} in acetone. The 78K {sup 57}Fe Mössbauer spectra of montmorillonite samples reflected magnetically split spectrum part indicating the intercalation of iron into the interlayer of montmorillonite via the treatment with FeCl {sub 3}+acetone and washed with water until the initial pH=2.3 increased to pH=4.14. It was found that the occurrence of intercalated iron in the form of oxide-oxihydroxide in montmorillonite increases with the pH. Intercalation was confirmed by the gradual increase in the basal spacing d{sub 001} with pH.

  9. Eco-Friendly Magnetic Iron Oxide Pillared Montmorillonite for Advanced Catalytic Degradation of Dichlorophenol

    Science.gov (United States)

    Eco-friendly pillared montmorillonites, in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties that are applicable for environmental decontamination. Completely “green” and effective composite was synthesized using mild reactio...

  10. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    Energy Technology Data Exchange (ETDEWEB)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed [Sharif University of Technology, Tehran (Iran, Islamic Republic of). Dept. of Chemistry]. E-mail: mhashemi@sharif.edu

    2005-09-15

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  11. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    International Nuclear Information System (INIS)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed

    2005-01-01

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  12. Solvent Free Preparation of p-Cymene from Limonene Using Vietnamese Montmorillonite

    DEFF Research Database (Denmark)

    Nguyen, Thao-Tran Thi; Duus, Fritz; Le, Thach Ngoc

    2013-01-01

    p-Cymene, an important intermediate in industrial chemistry, has been prepared in good yields by thermally induced dehydrogenation of limonene under solvent-free reaction conditions using Vietnamese montmorillonite as an efficient green catalyst.......p-Cymene, an important intermediate in industrial chemistry, has been prepared in good yields by thermally induced dehydrogenation of limonene under solvent-free reaction conditions using Vietnamese montmorillonite as an efficient green catalyst....

  13. Seawater Durability of Nano-Montmorillonite Modified Single-Lap Joining Epoxy Composite Laminates

    OpenAIRE

    ULUS, Hasan; KAYBAL, Halil Burak; DEMİR, Okan; TATAR, Ahmet Caner; SENYURT, Muhammed Ali; AVCI, Ahmet

    2018-01-01

    The objective of this study was to investigate of nano-montmorillonite modified epoxy composite single-lap bonded joints, after being exposed to seawater immersion in order to understand the effect of seawater environment on their performance. To prepare the nano adhesives, nano montmorillonite (2 wt %) was incorporated into epoxy resin. Composite bonded specimens which manufactured with VARIM (Vacuum Assisted Resin Infusion Method) were prepared accordance with ASTM D5868-01 and immersed in ...

  14. Adsorption of Carbon Dioxide, Methane, and Their Mixtute by Montmorillonite in the Presence of Water

    KAUST Repository

    Kadoura, Ahmad Salim

    2016-01-16

    Using grand canonical Monte Carlo (GCMC) simulations, we study the adsorption behavior of CH4, CO2, and their mixture at 298.15 K and pressures up to 50 bar in Na-, Cs-, and Ca-montmorillonite clays in the presence of water. Montmorillonite clays in the presence of preadsorbed water, preferentially adsorb CO2 over CH4 during both pure component and mixture adsorption. The atomistic model we have used, gives good agreement with available single-component experimental adsorption isotherms, for CH4 and CO2 molecules adsorbed onto montmorillonite clays in the presence of water. We observe the general trend that the presence of increasing preadsorbed water content in the clay interlayers, reduced adsorption amounts of pure CH4 and CO2 molecules. With a relatively large basal spacing (d= 30 Å), the favorability of adsorption of CO2 by montmorillonite at relatively low pressures and intermediate water contents has been demonstrated using simulations. GCMC simulation is also used to assess the effect of water on the adsorption of N2/CH4, H2 S/CH4, CO2/N2, and CO2/H2 S binary mixtures in Na-montmorillonite clay. The ideal adsorbed solution theory is shown to agree well with the observed adsorption capacities and selectivities of mixtures in Na-montmorillonite clay.

  15. Montmorillonite ameliorates hyperthyroidism of rats and mice attributed to its adsorptive effect.

    Science.gov (United States)

    Cai, Yan; Meng, Xin-fang; Cao, Yong-xiao; Lu, Hua; Zhu, Shao-fei; Zhou, Liang-zhen

    2006-12-03

    The present study aims to evaluate the adsorbing effect of montmorillonite on thyroid hormone in the entero-hepatic circulation. The concentration of thyroid hormone in the serum of hyperthyroidism model rats and in solution was measured by radioimmunoassay and ultraviolet spectrometry, respectively. The body weight, temperature, and consumption of food and water were observed in hyperthyroidism model rats. Furthermore, hypoxia tolerance, sodium-pentobarbital-induced sleep time, spontaneous activities were measured on hyperthyroidism model mice after being treated with montmorillonite. Results showed that montmorillonite adsorbed thyroxin (T(4)) and triiodothyronine (T(3)) in vitro. Montmorillonite at dosage of 1.0 g/kg and 0.3 g/kg decreased thyroid hormone levels on hyperthyroidism model rats; Montmorillonite (2.0 g/kg and 0.6 g/kg) prolonged the sleep time, improved the hypoxia tolerant capacity and reduced the spontaneous activities of the hyperthyroidism model mice. These results suggest montmorillonite has anti-hyperthyroidism effect attributed to its adsorptive effect.

  16. Confirmation tests of construction method and initial performance quality for low permeable engineered barrier in side part of radioactive waste disposal facilities

    International Nuclear Information System (INIS)

    Yamada, Atsuo; Chijimatsu, Masakazu; Akiyama, Yoshihiro; Komine, Hideo; Iizuka, Atsushi

    2016-01-01

    As for the low permeable layer, important functions are expected as an engineered barrier of radioactive waste disposal for low-level waste with comparatively high radiation levels. On examining the construction methods of this low permeable layer, it is important to confirm the possibility of the construction in the conditions similar to the actual constructed conditions with a true scale size. Therefore, the construction examination for the side part of the low permeable layer by bentonite and the performance check test of the low permeable layer were carried out. The result of the construction examination showed that the possibility of the construction were confirmed, and the result of performance check test showed that it was possible to ensure the required performance of the low permeable layer, such as hydraulic conductivity. (author)

  17. The in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory. Examination of backfill material using muck from URL construction

    International Nuclear Information System (INIS)

    Nakayama, Masashi; Ohno, Hirokazu; Tanai, Kenji; Fujita, Tomoo; Sugita, Yutaka

    2016-06-01

    The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, “Geoscientific Research” and “Research and Development on Geological Disposal Technologies”, and proceeds in three overlapping phases, “Phase I: Surface-based investigations”, “Phase II: Investigations during tunnel excavation” and “Phase III: Investigations in the underground facilities”, over a period of around 20 years. Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) was prepared from 2013 to 2014 fiscal year at G.L.-350m gallery (Niche No.4), and heating by electric heater in simulated overpack started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal – Hydrological – Mechanical – Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. In EBS experiment, the backfill material using mixture of bentonite and muck from Horonobe URL construction was used for backfilling a part of Niche No.4. This report shows the results of properties of the backfill material, confirmation test of compaction method and making backfill material block, and so on. From these results, it was confirmed that the backfill material would satisfy target value of the permeability and the swelling pressure. (author)

  18. Waste package/engineered barrier system design concepts for the direct disposal of spent fuel in the potential United States' repository at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Stahl, D.; Harrison, D.J.

    1993-01-01

    The goal of the US Department of Energy's (DOE) Yucca Mountain Site Characterization Project (YMP) waste package development program is to design a waste package and associated engineered barrier system (EBS) that meets the applicable regulatory requirements for safe disposal of spent nuclear fuel and solidified high-level waste (HLW) in a geologic repository. Attainment of this goal relies on a multi-barrier approach, the unsaturated nature of the Yucca Mountain site, consideration of technical alternatives, and sufficient resolution of technical and regulatory uncertainties. To accomplish this, an iterative system engineering approach will be used. The NWPA of 1982 limits the content of the first US repository to 70,000 metric tons of heavy metal (MTHM). The DOE Mission Plan describes the implementation of the provisions of the NWPA for the waste management system. The Draft 1988 approach will involve selecting candidate designs, evaluating them against performance requirements, and then selecting one or two preferred designs for further detailed evaluation and final design. The reference design of the waste package described in the YMP Site Characterization Plan is a thin-walled, vertical borehole-emplaced waste package with an air gap between the package and the rock wall. The reference design appeared to meet the design requirement. However, the degree of uncertainty was large. This uncertainty led to considering several more-robust design concepts during the Advanced Conceptual Design phase of the program that include small, drift-emplaced packages and higher capacity, drift-emplaced packages, both partially and totally self-shielded. Metallic as well as ceramic materials are being considered

  19. Laboratory Testing of a MEMS Sensor System for In-Situ Monitoring of the Engineered Barrier in a Geological Disposal Facility

    Directory of Open Access Journals (Sweden)

    Wenbin Yang

    2017-05-01

    Full Text Available Geological disposal facilities for radioactive waste pose significant challenges for robust monitoring of environmental conditions within the engineered barriers that surround the waste canister. Temperatures are elevated, due to the presence of heat generating waste, relative humidity varies from 20% to 100%, and swelling pressures within the bentonite barrier can typically be 2–10 MPa. Here, we test the robustness of a bespoke design MEMS sensor-based monitoring system, which we encapsulate in polyurethane resin. We place the sensor within an oedometer cell and show that despite a rise in swelling pressure to 2 MPa, our relative humidity (RH measurements are unaffected. We then test the sensing system against a traditional RH sensor, using saturated bentonite with a range of RH values between 50% and 100%. Measurements differ, on average, by 2.87% RH, and are particularly far apart for values of RH greater than 98%. However, bespoke calibration of the MEMS sensing system using saturated solutions of known RH, reduces the measurement difference to an average of 1.97% RH, greatly increasing the accuracy for RH values close to 100%.

  20. Sorption/Desorption Interactions of Plutonium with Montmorillonite

    Science.gov (United States)

    Begg, J.; Zavarin, M.; Zhao, P.; Kersting, A. B.

    2012-12-01

    Plutonium (Pu) release to the environment through nuclear weapon development and the nuclear fuel cycle is an unfortunate legacy of the nuclear age. In part due to public health concerns over the risk of Pu contamination of drinking water, predicting the behavior of Pu in both surface and sub-surface water is a topic of continued interest. Typically it was assumed that Pu mobility in groundwater would be severely restricted, as laboratory adsorption studies commonly show that naturally occurring minerals can effectively remove plutonium from solution. However, evidence for the transport of Pu over significant distances at field sites highlights a relative lack of understanding of the fundamental processes controlling plutonium behavior in natural systems. At several field locations, enhanced mobility is due to Pu association with colloidal particles that serve to increase the transport of sorbed contaminants (Kersting et al., 1999; Santschi et al., 2002, Novikov et al., 2006). The ability for mineral colloids to transport Pu is in part controlled by its oxidation state and the rate of plutonium adsorption to, and desorption from, the mineral surface. Previously we have investigated the adsorption affinity of Pu for montmorillonite colloids, finding affinities to be similar over a wide range of Pu concentrations. In the present study we examine the stability of adsorbed Pu on the mineral surface. Pu(IV) at an initial concentration of 10-10 M was pre-equilibrated with montmorillonite in a background electrolyte at pH values of 4, 6 and 8. Following equilibration, aliquots of the suspensions were placed in a flow cell and Pu-free background electrolyte at the relevant pH was passed through the system. Flow rates were varied in order to investigate the kinetics of desorption and hence gain a mechanistic understanding of the desorption process. The flow cell experiments demonstrate that desorption of Pu from the montmorillonite surface cannot be modeled as a simple

  1. Schottky barrier and band edge engineering via the interfacial structure and strain for the Pt/TiO2 heterostructure.

    Science.gov (United States)

    Ma, Xiangchao; Wu, Xin; Wang, Yucheng; Dai, Ying

    2017-07-19

    Charge transfer across the Pt/TiO 2 interface, which is mainly determined by the interface Schottky barrier height (SBH), is an important process in the (photo)catalytic and electronic applications of the Pt/TiO 2 composite. Therefore, systematic investigation of the factors that affect the interface SBH is indispensable for understanding and optimizing its performance. In this work, a systematic study of the effects of the interfacial structure and strain on the SBH of the Pt/TiO 2 (001) interface has been carried out based on the first-principles calculations. The results of interface adhesion energy show that two different interfacial structures for the Pt/TiO 2 (001) heterointerface may exist experimentally, namely, O-Pt bonding and Ti-Pt bonding. Moreover, the interfacial structures result in not only different values for the SBH, but also different dependences of the SBH on strain. Detailed investigations show that these versatile modulations of the SBH with the structure and strain are mainly attributed to the strong dependence of the band edges of TiO 2 and the interfacial potential alignments on the strain and structure, suggesting that these results are general and may be applicable to other metal/TiO 2 heterostructures.

  2. Charge plasma based source/drain engineered Schottky Barrier MOSFET: Ambipolar suppression and improvement of the RF performance

    Science.gov (United States)

    Kale, Sumit; Kondekar, Pravin N.

    2018-01-01

    This paper reports a novel device structure for charge plasma based Schottky Barrier (SB) MOSFET on ultrathin SOI to suppress the ambipolar leakage current and improvement of the radio frequency (RF) performance. In the proposed device, we employ dual material for the source and drain formation. Therefore, source/drain is divided into two parts as main source/drain and source/drain extension. Erbium silicide (ErSi1.7) is used as main source/drain material and Hafnium metal is used as source/drain extension material. The source extension induces the electron plasma in the ultrathin SOI body resulting reduction of SB width at the source side. Similarly, drain extension also induces the electron plasma at the drain side. This significantly increases the SB width due to increased depletion at the drain end. As a result, the ambipolar leakage current can be suppressed. In addition, drain extension also reduces the parasitic capacitances of the proposed device to improve the RF performance. The optimization of length and work function of metal used in the drain extension is performed to achieve improvement in device performance. Moreover, the proposed device makes fabrication simpler, requires low thermal budget and free from random dopant fluctuations.

  3. Characterisation, in vitro release study, and antibacterial activity of montmorillonite-gentamicin complex material

    International Nuclear Information System (INIS)

    Rapacz-Kmita, A.; Bućko, M.M.; Stodolak-Zych, E.; Mikołajczyk, M.; Dudek, P.; nd Department of Surgery, Kopernika 21, 31-501 Krakow (Poland))" data-affiliation=" (Jagiellonian University, Medical College, 2nd Department of Surgery, Kopernika 21, 31-501 Krakow (Poland))" >Trybus, M.

    2017-01-01

    The present paper concerns the potential use of montmorillonite as a drug carrier and focusses on the intercalation of the studied clay with gentamicin (an aminoglycoside antibiotic) at various temperatures (20, 50 and 80 °C). The experiments were performed to identify the temperature required for the optimum intercalation of gentamicin into the interlayer of montmorillonite. The structural and microstructural properties of gentamicin and the potential for introducing it between smectite clay layers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopic techniques, and SEM with EDS analysis. Additionally, the in vitro drug release behaviour of the montmorillonite-gentamicin complex and its antibacterial activity against Escherichia coli (E. coli) bacteria was investigated. Based on these studies, the impact of temperature on the intercalation of the drug between layers of smectite was evaluated. It was found that an intercalation temperature of 50 °C resulted in the highest shift in the position of principle peak d (001) as measured by XRD, suggesting, that the greatest amount of gentamicin had been introduced into the interlayer space of montmorillonite at this temperature. Subsequently, the montmorillonite-gentamicin complex material obtained at 50 °C revealed the greatest capacity for killing E. coli bacteria during an in vitro test. - Highlights: • A novel montmorillonite-gentamicin hybrid materials was prepared as potential drug carrier. • Optimal conditions for the intercalation of gentamicin into the interlayer space of montmorillonite were tested. • The MMT-G complex material obtained at 50 °C revealed the greatest capacity for killing E. coli during the inhibitory zone test. • Modulating drug delivery was monitored and confirmed in in vitro drug release study.

  4. Effects of Graded Levels of Montmorillonite on Performance, Hematological Parameters and Bone Mineralization in Weaned Pigs

    Directory of Open Access Journals (Sweden)

    Q. W. Duan

    2013-11-01

    Full Text Available The aim of this study was to investigate the effects of graded levels of montmorillonite, a constituent of clay, on performance, hematological parameters and bone mineralization in weaned pigs. One hundred and twenty, 35-d-old crossbred pigs (Duroc×Large White×Landrace, 10.50±1.20 kg were used in a 28-d experiment and fed either an unsupplemented corn-soybean meal basal diet or similar diets supplemented with 0.5, 1.0, 2.5 or 5.0% montmorillonite added at the expense of wheat bran. Each treatment was replicated six times with four pigs (two barrows and two gilts per replicate. Feed intake declined (linear and quadratic effect, p< 0.01 with increasing level of montmorillonite while feed conversion was improved (linear and quadratic effect, p<0.01. Daily gain was unaffected by dietary treatment. Plasma myeloperoxidase declined linearly (p = 0.03 with increasing dietary level of montmorillonite. Plasma malondialdehyde and nitric oxide levels were quadratically affected (p<0.01 by montmorillonite with increases observed for pigs fed the 0.5 and 1.0% levels which then declined for pigs fed the 2.5 and 5.0% treatments. In bone, the content of potassium, sodium, copper, iron, manganese and magnesium were decreased (linear and quadratic effect, p<0.01 in response to an increase of dietary montmorillonite. These results suggest that dietary inclusion of montmorillonite at levels as high as 5.0% does not result in overt toxicity but could induce potential oxidative damage and reduce bone mineralization in pigs.

  5. Characterisation, in vitro release study, and antibacterial activity of montmorillonite-gentamicin complex material

    Energy Technology Data Exchange (ETDEWEB)

    Rapacz-Kmita, A., E-mail: kmita@agh.edu.pl [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza 30, 30-059 Krakow (Poland); Bućko, M.M.; Stodolak-Zych, E. [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza 30, 30-059 Krakow (Poland); Mikołajczyk, M. [The University Hospital in Krakow, Division of Microbiology, Kopernika 19, 31-501 Krakow (Poland); Dudek, P. [AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Mickiewicza 30, 30-059 Krakow (Poland); Trybus, M. [Jagiellonian University, Medical College, 2" n" d Department of Surgery, Kopernika 21, 31-501 Krakow (Poland)

    2017-01-01

    The present paper concerns the potential use of montmorillonite as a drug carrier and focusses on the intercalation of the studied clay with gentamicin (an aminoglycoside antibiotic) at various temperatures (20, 50 and 80 °C). The experiments were performed to identify the temperature required for the optimum intercalation of gentamicin into the interlayer of montmorillonite. The structural and microstructural properties of gentamicin and the potential for introducing it between smectite clay layers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopic techniques, and SEM with EDS analysis. Additionally, the in vitro drug release behaviour of the montmorillonite-gentamicin complex and its antibacterial activity against Escherichia coli (E. coli) bacteria was investigated. Based on these studies, the impact of temperature on the intercalation of the drug between layers of smectite was evaluated. It was found that an intercalation temperature of 50 °C resulted in the highest shift in the position of principle peak d{sub (001)} as measured by XRD, suggesting, that the greatest amount of gentamicin had been introduced into the interlayer space of montmorillonite at this temperature. Subsequently, the montmorillonite-gentamicin complex material obtained at 50 °C revealed the greatest capacity for killing E. coli bacteria during an in vitro test. - Highlights: • A novel montmorillonite-gentamicin hybrid materials was prepared as potential drug carrier. • Optimal conditions for the intercalation of gentamicin into the interlayer space of montmorillonite were tested. • The MMT-G complex material obtained at 50 °C revealed the greatest capacity for killing E. coli during the inhibitory zone test. • Modulating drug delivery was monitored and confirmed in in vitro drug release study.

  6. The effect of exchangeable cations in clinoptilolite and montmorillonite on the adsorption of aflatoxin B1

    Directory of Open Access Journals (Sweden)

    DRAGAN STOJSIC

    2001-08-01

    Full Text Available The adsorption of aflatoxin B1 (AFB1 by cation-exchanged clinoptilolite zeolitic tuff and montmorillonite was investigated at 37°C and pH 3.8 from an aqueous electrolyte having a composition similar to that of gastric juices of animals. Both minerals were exchanged from the natural form to the sodium form and then to the Cu2+, Zn2+ and Co2+-rich forms. The cation exchange was different for the different cations, but in all cases the exchanges were larger on montmorillonite than on clinoptilolite. The degree of exchange on montmorillonite was 76 % for copper (from a total of CEC 0.95 meq/g, Cu2+ –0.73 meq/g and 85 % for zinc and cobalt. Under the same conditions (concentration, temperature, pH, contact time, the degree of exchange on zeolitic tuff was 12 % for Cu2+ (from a total CEC of 1.46 meq/g, Cu2+ –0.17 meq/g, 8 % for Zn2+ and 10 % for Co2+. Both groups of mineral adsorbents showed high AFB1 chemisorption indexes (ca. For the montmorillonite forms, ca ranged from 0.75 for the Cu-exchanged montmorillonite to 0.89 for the natural Ca-form, 0.90 for the Zn-exchanged form and 0.93 for the Co-exchanged montmorillonite. The adsorption of AFB1 on the different exchanged forms of clinoptilolite gave similar values of ca for the Cu and Ca forms (0.90 and values of 0.94 and 0.95 for the Zn- and Co-exchanged form. The impact of the mineral adsorbents on the reduction of essential nutrients present in animal feed (Cu, Zn, Mn and Co showed that the Ca-rich montmorillonite had a higher capability for the reduction of the microelements than the Ca-rich clinoptilolite.

  7. Behind adhesion of uranyl onto montmorillonite surface: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.; Zaoui, A., E-mail: azaoui@polytech-lille.fr

    2013-10-15

    Highlights: • We investigated the adsorption of uranyl onto Montmorillonite surface. • We studied the surface energy between layered Montmorillonite sheets. • We studied the work of adhesion between radionuclide and charged Montmorillonite. -- Abstract: We have performed molecular dynamics simulations to investigate the adsorption of radionuclide elements species onto substituted Montmorillonite (001) surface in the presence of different counterions. The structure and the dynamics of uranyl ion as well as its aquo, chloride ion, and carbonate complexes are analyzed. In addition, we have studied the surface energy between layered Montmorillonite sheets and the work of adhesion between radionuclide and charged Montmorillonite. The clay model used here is a Wyoming-type Montmorillonite with 0.75e negative charge per unit cell resulting from substitutions in Octahedral and Tetrahedral sheets. The system model was constructed based on CLAYFF force field potential model. To evaluate the thermodynamic work of adhesion, each surface and clay layer regions are converted to a thin film model. One and two species of radionuclide elements (UO{sub 2}(H{sub 2}O){sub 5},UO{sub 2}CO{sub 3}(H{sub 2}O){sub 5}, and UO{sub 2}Cl{sub 2}(H{sub 2}O){sub 5}) were deposited near the clay surface in a pseudo-two-dimensional periodic cell. Analysis shows that the uranyl ion structure is preserved with two axial oxygen atoms detected at 1.8 Å. Radial distribution functions results indicate that average U-O{sub w} distances are 2.45–2.61 Å, and 2.29–2.40 Å for U-O{sub c} distance. Average U-Cl distances are 2.78–3.08 Å, which is relatively larger than that of Uranium atom-Oxygen atom because of electrostatic factors.

  8. Highly Controlled Diffusion Drug Release from Ureasil-Poly(ethylene oxide)-Na+-Montmorillonite Hybrid Hydrogel Nanocomposites.

    Science.gov (United States)

    Jesus, Celso R N; Molina, Eduardo F; Pulcinelli, Sandra H; Santilli, Celso V

    2018-06-06

    In this work, we report the effects of incorporation of variable amounts (1-20 wt %) of sodium montmorillonite (MMT) into a siloxane-poly(ethylene oxide) hybrid hydrogel prepared by the sol-gel route. The aim was to control the nanostructural features of the nanocomposite, improve the release profile of the sodium diclofenac (SDCF) drug, and optimize the swelling behavior of the hydrophilic matrix. The nanoscopic characteristics of the siloxane-cross-linked poly(ethylene oxide) network, the semicrystallinity of the hybrid, and the intercalated or exfoliated structure of the clay were investigated by X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. The correlation between the nanoscopic features of nanocomposites containing different amounts of MMT and the swelling behavior revealed the key role of exfoliated silicate in controlling the water uptake by means of a flow barrier effect. The release of the drug from the nanocomposite displayed a stepped pattern kinetically controlled by the diffusion of SDCF molecules through the mass transport barrier created by the exfoliated silicate. The sustained SDCF release provided by the hybrid hydrogel nanocomposite could be useful for the prolonged treatment of painful conditions, such as arthritis, sprains and strains, gout, migraine, and pain after surgical procedures.

  9. Experimental Study on the Interaction Between Contacting Barrier Materials for Containment of Radioactive Wastes

    Science.gov (United States)

    Huang, W. H.; Chang, H. C.

    2017-12-01

    The disposal of low- and intermediate-level radioactive wastes requires use of multi-barriers for isolation of the wastes from the biosphere. Typically, the engineered barriers are composed of a concrete vault, buffer and backfill materials. Zhishin clay and Black Hill bentonite were used as raw clay material in making buffer and backfill materials in this study. These clays were compacted to make buffer material, or mixed with Taitung area argillite to produce backfill material for potential application as barriers for the disposal of low- and intermediate-level radioactive wastes. The interaction between concrete barrier and the buffer/backfill material is simulated by an accelerated migration test to investigate the effect of contacting concrete on the expected functions of buffer/backfill material. The results show buffer material close to the contact with concrete exhibits significant change in the ratio of calcium/sodium exchange capacity, due to the move of calcium ions released from the concrete. The shorter the distance from the contacting interface, the ratio of the calcium/sodium concentration in buffer/backfill materials increases. The longer the distance from the interface, the effect of the contact on alteration in clays become less significant. Also, some decreases in swelling capacity in the buffer/backfill material near the concrete-backfill interface are noted. Finally, a comparison is made between Zhisin clay and Balck Hill bentonite on the interaction between concrete and the two clays. Black Hill bentonite was found to be influenced more by the interaction, because of the higher content of montmorillonite. On the other hand, being a mixture of clay and sand, backfill material is less affected by the decalsification of concrete at the contact than buffer material.

  10. Adsorption of Benzene by “Green” functionalization of Montmorillonite

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    Anjum Hirra

    2018-01-01

    Full Text Available The capacity of organically modified Montmorillonite (MMT clay to adsorb nonpolar organic compound (benzene in an aqueous solution, was investigated under the batch process. MMT was pretreated (centrifuged and then functionalized with green intercalating agent i.e. 1-hexyl-3-methyl imadazolium chloride [HMim][Cl]. The characterization through Fourir Transoform Infrared Spectroscopy (FTIR, Differential Scanning Calorimeter (DSC and Field Emission Scanning Electron Microscope (FE-SEM confirmed the presence of the oxygen containing functional groups, changes in melting point and variation in the morphological properties. The governing parameters for the sorption of benzene such as the effect of contact time, pH, adsorbent dose and rotation were studied. The kinetic data conformed to pseuodo 2nd order kinetic model and the isotherm experimental data were a better fit to Langmuir model with maximum adsorption capacity of 588.23mg/g under experimental conditions. Overall, MMT intercalated with 1-hexyl-3-methyl imadazolium chloride is a promising environmental friendly adsorbent for the abatement of benzene in an aqueous solution.

  11. Sorption of 241Am onto montmorillonite, illite and hematite colloids

    International Nuclear Information System (INIS)

    Degueldre, C.; Ulrich, H.J.; Silby, H.

    1994-01-01

    Actinide sorption on colloids may be described as a competition between the formation of complexes in solution and the build up of surface complexes. The role of particle and of carbonate concentrations on the sorption/desorption of 241 Am on montmorillonite, illite and hematite colloids is investigated. Since the partition coefficient (K p ) values are virtually independent of the colloid concentrations, within the range 1 to 300 ppm, no significant aggregation takes place in the sorption/desorption experiment. At pH 8, a slight decrease of K p is observed if the concentration of total carbonate exceeds 10 -2 M. The formation of the carbonato- (and hydroxo-carbonato-) complexes in the solution competes with the formation of surface complexes on the colloids. A relationship between the sorption coefficient and the complexation of 241 Am in the solution has been found. This leads to the conclusion that, besides free americium cation, the hydroxo-, and carbonato- as well as the mixed hydroxo-carbonato-complexes are sorbed. Only when the tricarbonatocomplex [Am(CO 3 ) 3 ] 3- prevails (total carbonate concentration > 10 -2 M), a significant decrease of the distribution coefficient is observed. At pH 10 this decrease disappears because under these conditions the strong hydroxo-complexes dominate. A pragmatic and relatively simple application of surface complexation model describes the observed features. (orig.)

  12. Catalytic Ethanol Dehydration over Different Acid-activated Montmorillonite Clays.

    Science.gov (United States)

    Krutpijit, Chadaporn; Jongsomjit, Bunjerd

    2016-01-01

    In the present study, the catalytic dehydration of ethanol to obtain ethylene over montmorillonite clays (MMT) with mineral acid activation including H2SO4 (SA-MMT), HCl (HA-MMT) and HNO3 (NA-MMT) was investigated at temperature range of 200 to 400°C. It revealed that HA-MMT exhibited the highest catalytic activity. Ethanol conversion and ethylene selectivity were found to increase with increased reaction temperature. At 400°C, the HA-MMT yielded 82% of ethanol conversion having 78% of ethylene yield. At lower temperature (i.e. 200 to 300°C), diethyl ether (DEE) was a major product. The highest activity obtained from HA-MMT can be attributed to an increase of weak acid sites and acid density by the activation of MMT with HCl. It can be also proven by various characterization techniques that in most case, the main structure of MMT did not alter by acid activation (excepted for NA-MMT). Upon the stability test for 72 h during the reaction, the MMT and HA-MMT showed only slight deactivation due to carbon deposition. Hence, the acid activation of MMT by HCl is promising to enhance the catalytic dehydration of ethanol.

  13. Experimental and theoretical study of Co sorption in clay montmorillonites

    Science.gov (United States)

    Gil Rebaza, A. V.; Montes, M. L.; Taylor, M. A.; Errico, L. A.; Alonso, R. E.

    2018-03-01

    Montmorillonite (MMT) clays are 2:1 layered structures which in natural state may allocate different hydrated cations such as M-nH2O (M = Na, Ca, Fe, etc) in its interlayer space. Depending on the capability for ion sorption, these materials are interesting for environmental remediation. In this work we experimentally study the Co sorption in a natural Na-MMT using UV-visible spectrometry and XRD on semi-oriented samples, and then analyze the sorption ability of this clay by means of ab initio calculation performed on pristine MMT. The structural properties of Na-MMT and Co-adsorbed MMT, and the hyperfine parameters at different atomic sites were analyzed and compared with the experimental ones for the first, and for the case of the hyperfine parameters, presented for the first time for the last. The theoretical predictions based on total energy considerations confirm that Co incorporation replacing Na is energetically favorable. Also, the basal spacing d001 experimentally obtained is well reproduced.

  14. Montmorillonite polyaniline nanocomposites: Preparation, characterization and investigation of mechanical properties

    International Nuclear Information System (INIS)

    Soundararajah, Q.Y.; Karunaratne, B.S.B.; Rajapakse, R.M.G.

    2009-01-01

    The interest in clay polymer nanocomposites (CPN) materials, initially developed by researchers at Toyota, has grown dramatically over the last decade. They have attracted great interest, both in industry and in academia, because they often exhibit remarkable improvement in materials' properties when compared with virgin polymer or conventional micro- and macro-composites. These improvements can include high moduli, increased strength and heat resistance, decreased gas permeability and flammability, optical transparency and increased biodegradability of biodegradable polymers. Such enhancement in the properties of nanocomposites occurs mostly due to their unique phase morphology and improved interfacial properties. Because of these enhanced properties they find applications in the fields of electronics, automobile industry, packaging, and construction. This study aims at investigating the mechanical property enhancement of polyaniline (PANI) intercalated with montmorillonite (MMT) clay. The MMT-PANI nanocomposites displayed improved mechanical properties compared to the neat polymer or clay. The enhancement was achieved at low clay content probably due to its exfoliated structure. The increased interfacial areas and improved bond characteristics may attribute to the mechanical property enhancement

  15. Confinement effects and mechanistic aspects for montmorillonite nanopores.

    Science.gov (United States)

    Li, Xiong; Zhu, Chang; Jia, Zengqiang; Yang, Gang

    2018-08-01

    Owing to the ubiquity, critical importance and special properties, confined microenvironments have recently triggered overwhelming interest. In this work, all-atom molecular dynamics simulations have been conducted to address the confinement effects and ion-specific effects for electrolyte solutions within montmorillonite nanopores, where the pore widths vary with a wide range. The adsorption number, structure, dynamics and stability of inner- and outer-sphere metal ions are affected by the change of pore widths (confinement effects), while the extents are significantly dependent on the type of adsorbed species. The type of adsorbed species is, however, not altered by the magnitude of confinement effects, and confinement effects are similar for different electrolyte concentrations. Ion-specific effects are pronounced for all magnitudes of confinement effects (from non- to strong confined conditions), and Hofmeister sequences of outer-sphere species are closely associated with the magnitude of confinement effects while those of inner-sphere species remain consistent. In addition, mechanistic aspects of confinement have been posed using the electrical double layer theories, and the results can be generalized to other confined systems that are ubiquitous in biology, chemistry, geology and nanotechnology. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Sorption of cesium on montmorillonite and effect of salt concentration

    International Nuclear Information System (INIS)

    Atun, G.; Bilgin, B.; Mardinli, A.

    1996-01-01

    The sorption behavior of cesium on montmorillonite type[e clay was studied by using radioactivity measurements. Concentrations of Cs + ions ranged from 10 -6 to 10 -2 M. Cesium retention reduced with increasing salt concentration which was varied between 10 -4 and 10 -1 M. Selectivity coefficients K CsNa for the exchange between Cs and Na were calculated for different equivalent fractions of Cs on the solid phase. Using the K CsNa values, free energy change was found to be 7.8 kJ/mol. The data could be fitted to a Freundlich isotherm, and empirical Freundlich parameters enabled the generation of a site distribution function. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm, a mean energy of sorption of 8.6kJ/mole was calculated which corresponds to the energy of ion exchange reactions. The values of energy changes calculated by using two different methods were in good agreement. (author)

  17. The effect of dispersion technique of montmorillonite on polyisocyanurate nanocomposites

    Science.gov (United States)

    Cabulis, U.; Fridrihsone, A.; Andersons, J.; Vlcek, T.

    2014-05-01

    The biomass represents an abundant, renewable, competitive and low cost resource that can play an alternative role to petrochemical resources. The central topic of the research activity reported is the use of rape seed oil (RO) as a raw material for the production of rigid polyisocyanurate foams (PIR). The content of the renewable resource-derived polymers achieved in ready foams is up to 20%. By using biopolymers as a matrix, a prospective way is to reinforce them with nanoparticles, organically modified clays, for improvement of mechanical properties while, at the same time, replacing petrochemical raw materials. Organoclay Cloisite® 15A was tested as a filler of PIR foams. Three different techniques - ultrasonification, mixing by three-roll mills, and high-pressure homogenization were used for dispergation of nanoclays in polyols. Composite polyisocyanurate foams and solid polymer samples were produced and tested for stiffness and strength. This paper discusses the studies into the use of RO as a renewable source in rigid PIR foams filled with organomodified montmorillonite clay with loadings from 1 to 5% by weight.

  18. Characterization of Polylactic Acid/ Microcrystalline Cellulose/ Montmorillonite Hybrid Composites

    International Nuclear Information System (INIS)

    Reza Arjmandi; Azman Hassan; Haafiz, M.K.M.; Zainoha Zakaria; Inuwa, I.M.

    2014-01-01

    The objective of this study is to investigate the effect of montmorillonite (MMT)/ microcrystalline cellulose (MCC) hybrid fillers on mechanical properties and morphological characteristics of polylactic acid (PLA) composites. PLA/ MMT nano composites and PLA/ MMT/ MCC hybrid composites were prepared by solution casting method. Morphology and tensile properties of PLA composites were investigated using Field emission scanning electron microscopy and Instron tensile testing machine. The maximum tensile strength of PLA/ MMT nano composites was obtained with 5 phr contents of MMT, which corresponding to 30.75 MPa. Based on optimized formulation of PLA/ MMT nano composites (5 phr MMT contents), various amounts of MCC (0 to 7 phr) were added into optimum formulation of PLA/ MMT in order to produce PLA/ MMT/ MCC hybrid composites. Fourier transform infrared spectroscopy revealed some level of interaction between PLA and both MMT and MCC in the hybrid composites. However, the percent elongation at break of the hybrid composites was generally higher than PLA/ MMT nano composites. Additionally, Young's modulus of the PLA/ MMT/ MCC hybrid composites increased gradually with increasing of MCC contents and was higher than PLA/ MMT at all compositions. The present results are the first among a series of experiments that have been designed in order to probe the effect of MMT and MCC in the PLA. (author)

  19. The influence of interfacial barrier engineering on the resistance switching of In2O3:SnO2/TiO2/In2O3:SnO2 device

    International Nuclear Information System (INIS)

    Liu Zi-Yu; Zhang Pei-Jian; Meng Yang; Li Dong; Meng Qing-Yu; Li Jian-Qi; Zhao Hong-Wu

    2012-01-01

    The I—V characteristics of In 2 O 3 :SnO 2 /TiO 2 /In 2 O 3 :SnO 2 junctions with different interfacial barriers are investigated by comparing experiments. A two-step resistance switching process is found for samples with two interfacial barriers produced by specific thermal treatment on the interfaces. The nonsynchronous occurrence of conducting filament formation through the oxide bulk and the reduction in the interfacial barrier due to the migration of oxygen vacancies under the electric field is supposed to explain the two-step resistive switching process. The unique switching properties of the device, based on interfacial barrier engineering, could be exploited for novel applications in nonvolatile memory devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Sensitivity of the engineered barrier system (EBS) release rate to alternative conceptual models of advective release from waste packages under dripping fractures

    International Nuclear Information System (INIS)

    Lee, J.H.; Atkins, J.E.; McNeish, J.A.; Vallikat, V.

    1996-01-01

    Simulations were conducted to analyze the sensitivity of the engineered barrier system (EBS) release rate to alternative conceptual models of the advective release from waste packages under dripping fractures. The first conceptual model assumed that dripping water directly contacts the waste form inside the 'failed' waste package, and radionuclides are released from the EBS by advection. The second conceptual model assumed that dripping water is diverted around the 'failed' waste package (because of the presence of corrosion products plugging the perforations) and dripping water is prevented from directly contacting the waste form. In the second model, radionuclides were assumed to transport through the perforations by diffusion, and, once outside the waste package, to be released from the EBS by advection. The second model was to incorporate more realism into the EBS release calculations. For the case with the second EBS release model, most radionuclides had significantly lower peak EBS release rates (from at least one to several orders of magnitude) than with the first EBS release model. The impacts of the alternative EBS release models were greater for the radionuclides with a low solubility (or solubility-limited radionuclides) than for the radionuclides with a high solubility (or waste form dissolution-limited radionuclides). The analyses indicated that the EBS release model representing advection through a 'failed' waste package (the first EBS release model) may be too conservative in predicting the EBS performance. One major implication from this sensitivity study was that a 'failed' waste package container with multiple perforations may still be able to perform effectively as an important barrier to radionuclide release. (author)

  1. Effect of humidity and interlayer cation on frictional strength of montmorillonite

    Science.gov (United States)

    Tetsuka, H.; Katayama, I.; Sakuma, H.; Tamura, K.

    2016-12-01

    Smectite has been ubiquitously seen in fault gouge (Schleicher et al., 2006; Kuo et al., 2009; Si et al., 2014; Kameda, 2015) and is characteristic by low frictional coefficient (Saffer et al., 2001; Ikari et al., 2007); consequently, it has a key role in fault dynamics. The frictional strength of montmorillonite (a typical type of smectite) is affected by mainly two factors, 1) hydration state and 2) interlayer cation. Previous laboratory experiments have shown that the frictional strength of montmorillonite changes with hydration state (Ikari et al., 2007) and with interlayer cation (Behnsen and Faulkner, 2013). However, experimental study for frictional strengths of interlayer cation-exchanged montmorillonite under controlled hydration state has not been reported. We are developing humidity control system in biaxial friction testing machine and try to investigate the effect of relative humidity and interlayer cation on frictional strength of montmorillonite. The humidity control system consists of two units, 1) the pressure vessel (core holder) unit controlled by a constant temperature and 2) the vapor generating unit controlled by variable temperature. We control relative humidity around sample, which is calculated from the temperature around sample and the vapor pressure at vapor generating unit. Preliminary experiments under controlled humidity show frictional coefficient of montmorillonite decrease with increasing relative humidity. In the meeting, we will report the systematic study of frictional coefficient as function of relative humidity and interlayer cation species.

  2. The influence of montmorillonite content on the kinetics of curing of epoxy nanocomposites

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2012-01-01

    Full Text Available In this work, the attention was paid at the investigation of montmorillonite dispersion in epoxy/amine systems due to improved final properties of the nanocomposites. The influence of different montmorillonite content on the kinetics of curing of epoxy/Jeffamine D-230 systems was followed by differential scanning calorimetry (DSC. The curing of epoxy nanocomposites was performed using dynamic regime at three different heating rates: 5, 10 and 20°C/min. Three isoconversional methods were applied: two integral (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods and one differential (Friedman method. The presence of montmorillonite (MMT causes the beginning of curing at lower temperatures. The shape of the DSC curves has been changed by the addition of MMT, supporting the hypothesis of a change in the reaction mechanism. For hybrids with 3 and 5 wt.% of MMT, the Eα dependence is very similar to those found for the reference system (epoxy/Jeffamine D-230 for the curing degree less than 60%. The hybrid with 10 wt.% of MMT has lower energy activation in regard to the referent system without montmorillonite. Greater differences are observed in the second part of the reaction, where it is known that the curing process is more controlled by diffusion (α>0.60. The Ea value increases at the end of the reaction (α→1, which was observed for all systems, and is more pronounced in the presence of montmorillonite. [Projekat Ministarstva nauke Republike Srbije, br. III45022

  3. XRD, TEM, and thermal analysis of Arizona Ca-montmorillonites modified with didodecyldimethylammonium bromide.

    Science.gov (United States)

    Sun, Zhiming; Park, Yuri; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L

    2013-10-15

    An Arizona SAz-2 calcium montmorillonite was modified by a typical dialkyl cationic surfactant (didodecyldimethylammonium bromide, abbreviated to DDDMA) through direct ion exchange. The obtained organoclays were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), high-resolution thermogravimetric analysis (HR-TG), and infrared emission spectroscopy (IES). The intercalation of surfactants greatly increased the basal spacing of the interlayers and the conformation arrangement of the loaded surfactant were assessed based on the XRD and TEM measurements. This work shows that the dialkyl surfactant can be directly intercalated into the montmorillonite without first undergoing Na(+) exchange. Moreover, the thermal stability of organoclays and the different arrangements of the surfactant molecules intercalated in the SAz-2 Ca-montmorillonite were determined by a combination of TG and IES techniques. The detailed conformational ordering of different intercalated surfactants under different conditions was also studied. The surfactant molecule DDDMA has proved to be thermally stable even at 400°C which indicates that the prepared organoclay is stable to significantly high temperatures. This study offers new insights into the structure and thermal stabilities of SAz-2 Ca-montmorillonite modified with DDDMA. The experimental results also confirm the potential applications of organic SAz-2 Ca-montmorillonites as adsorbents and polymer-clay nanocomposites. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Evaluation of particle release from montmorillonite gel by flowing groundwater based on the DLVO theory

    International Nuclear Information System (INIS)

    Kurosawa, Susumu; Nagasaki, Shinya; Tanaka, Satoru

    2007-01-01

    Theoretical study has been performed to clarify the ability of colloid release form the montmorillonite gel by the flowing groundwater. Evaluation of montmorillonite colloidal particles release from the bentonite buffer material is important for the performance assessment of radioactive waste disposal because the colloids may influence the radionuclide transport. In this study, the minimum groundwater flow rate required to tear off montmorillonite particles from surface of bentonite buffer was estimated from the shear stress on the gel front, which was calculated by the DLVO theory. The estimated shear force was converted to corresponding groundwater velocity by using Stoke's equation. The results indicated that groundwater velocity in a range of about 10 -5 to 10 -4 m/s would be necessary to release montmorillonite particles. This range is higher than the groundwater flow velocity found generally in deep geological media in Japan. This study suggests that the effect of montmorillonite particles release from the bentonite buffer on radionuclide transport is likely to be negligible in the performance assessment of high-level radioactive waste geological disposal. (author)

  5. Study of scenario 'mistake in determination of adsorbing properties of radionuclides on the materials of engineering barriers and host rock'

    International Nuclear Information System (INIS)

    Amosov, P.V.; Novozhilova, N.V.

    2008-01-01

    During investigations within the framework of this ASE of a storage facility, conceptual and mathematical models remained the same, as in SNE. Basic provisions of models, a solution 'tool' for diffusion equation taking into account radioactive decay and the chosen boundary conditions are presented in paper. The 79 Se isotope is chosen as basic analyzed radionuclide within the framework of the accepted ASE. The selection of this isotope can be substantiated by the following reasons: 1) Migration parameters of this radionuclide, in particular, the distribution coefficient of 79 Se isotope has specific enough values. For example, in granitoid formations (according to different research groups from Sweden, Finland, Switzerland during rather a small time range of experiments carrying out) the values of distribution coefficient vary within 20 times and thus its numerical value is small enough (0.0005 - 0.01 m 3 /kg). At the same time, the situation is reverse with cement materials: from references accessible to us only in one the value of this parameter is cited. 2) Performing calculations for the full list of radio-nuclides (in the SNE there were 8 of them) will require considerable labor expenditures and computer facilities resources: much processor time and much memory on a hard disk to store information. Since, when considering the selected ASE of facility there are accepted 4 areas of materials (the source, concrete, bentonite, the host rock) generally, it means practically a fourfold increase of all specified expenses in comparison with similar expenses for a SNE of facility. The main conclusions are: There are considered possible variants of error, which consequence is the 79 Se isotope transition in the category of a non-sorbing one in respective barrier of the near field that can conservatively lead to an increase of the facility hazard. If there is an error in selection of sorption parameters of 79 Se isotope in the host rock an increase in pollution of the

  6. Diffusion of helium and estimated diffusion coefficients of hydrogen dissolved in water-saturated, compacted Ca-montmorillonite

    International Nuclear Information System (INIS)

    Higashihara, Tomohiro; Sato, Seichi; Ohashi, Hiroshi; Otsuka, Teppei

    2001-01-01

    The diffusion coefficients of hydrogen gas dissolved in water-saturated, compacted montmorillonite are required to estimate the performance of bentonite buffer materials for geological disposal of nuclear waste. As part of the effort to determine the diffusion coefficients, the diffusion coefficients of helium in water-saturated, compacted calcium montmorillonite (Ca-montmorillonite) were determined as a function of dry density, 0.78 to 1.37x10 3 kg m -3 , by a transient diffusion method. The diffusion coefficients were from 8.3x10 -10 m 2 s -1 at 0.78x10 3 kgm -3 to 2.8x10 -10 m 2 s -1 at 1.37x10 3 kgm -3 . The data obtained by this diffusion experiment of helium were highly reproducible. The diffusion coefficients of helium in Ca-montmorillonite were somewhat larger than those previously obtained for helium in sodium montmorillonite (Na-montmorillonite). The diffusion coefficients of hydrogen gas in the montmorillonites were roughly estimated using the diffusion coefficients of helium. These estimates were based on assumptions that both helium and hydrogen molecules are non-adsorptive and that the geometric factors in the compacted montmorillonites are approximately the same for diffusion of helium and diffusion of hydrogen. (author)

  7. Experimental methodology to study radionuclide sorption and migration in geological formations and engineered barriers of waste repositories; Metodologia experimental para estudios de sorcion y migracion de radionucleidos en formaciones geologicas y barreras de almacenamientos de residuos

    Energy Technology Data Exchange (ETDEWEB)

    Rojo Sanz, H.

    2010-07-01

    In Spain, the waste management options include either the possibility of a final storage in a deep geological repository (DGR) or the centralized temporal surface disposal (CTS). DGRs are based in a multi-barrier concept with the geological barrier and including the vitrified waste, the metal containers and engineered barriers such as compacted bentonite and cement-based materials. On the other hand, CTS mainly considers concrete and cement to confine the metal canisters containing the waste. Radionuclide migration will mainly take place by the existence of chemical concentration gradients being thus diffusion the main transport mechanism or by the existence of hydraulic gradients due to the existence of water-conductive fractures. Radionuclide sorption/retention on the materials composing the natural and engineered barriers is the fundamental process controlling contaminant migration. The evaluation of sorption parameters and the understanding of the different mechanisms leading to radionuclide retention are very important issues. The study of diffusion processes is very relevant as well. This paper describes the main experimental methodologies applied to analyse radionuclide transport in the different barriers of radioactive repositories. Particularly we focused on obtaining of retention parameters as distribution coefficients, kd, or retardation factors, Rf, and diffusion coefficients of radionuclides. (Author) 6 refs.

  8. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

    International Nuclear Information System (INIS)

    Debiagi, Flavia; Mali, Suzana

    2011-01-01

    The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

  9. A curcumin activated carboxymethyl cellulose-montmorillonite clay nanocomposite having enhanced curcumin release in aqueous media.

    Science.gov (United States)

    Madusanka, Nadeesh; de Silva, K M Nalin; Amaratunga, Gehan

    2015-12-10

    A novel curcumin activated carboxymethylcellulose-montmorillonite nanocomposite is reported. A superabsorbent biopolymer; carboxymethyl cellulose (CMC) was used as an emulsifier for curcumin which is a turmeric derived water insoluble polyphenolic compound with antibacterial/anti-cancer properties. Montmorillonite (MMT) nanoclay was incorporated in the formulation as a matrix material which also plays a role in release kinetics. It was observed that water solubility of curcumin in the nanocomposite has significantly increased (60% release within 2h and 30 min in distilled water at pH 5.4) compared to pure curcumin. The prepared curcumin activated carboxymethylcellulose-montmorillonite nanocomposite is suitable as a curcumin carrier having enhanced release and structural properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Esterification of phenyl acetic acid with p-cresol using metal cation exchanged montmorillonite nanoclay catalysts.

    Science.gov (United States)

    Bhaskar, M; Surekha, M; Suma, N

    2018-02-01

    The liquid phase esterification of phenyl acetic acid with p -cresol over different metal cation exchanged montmorillonite nanoclays yields p -cresyl phenyl acetate. Different metal cation exchanged montmorillonite nanoclays (M n +  = Al 3+ , Zn 2+ , Mn 2+ , Fe 3+ , Cu 2+ ) were prepared and the catalytic activity was studied. The esterification reaction was conducted by varying molar ratio of the reactants, reaction time and catalyst amount on the yield of the ester. Among the different metal cation exchanged catalysts used, Al 3+ -montmorillonite nanoclay was found to be more active. The characterization of the material used was studied under different techniques, namely X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. The product obtained, p -cresyl phenyl acetate, was identified by thin-layer chromotography and confirmed by Fourier transform infrared, 1 H NMR and 13 C NMR. The regeneration activity of used catalyst was also investigated up to fourth generation.

  11. Physico-mechanical properties of silanized-montmorillonite reinforced chitosan-co-poly(maleic anhydride) composites

    Science.gov (United States)

    Saputra, O. A.; Fajrin, A.; Nauqinida, M.; Suryanti, V.; Pramono, E.

    2017-07-01

    To solve the problems of dependence on petroleum as starting material in the manufacturing of plastics in Indonesia, green plastic from biopolymer like chitosan to be one of promising options and alternative to replace the conventional plastics. However, to overcome the mechanical and physical properties of chitosan, the addition of reinforcement agent was introduced. In this study, silanized-montmorillonite (sMMt) has been prepared as a reinforcement agent in the chitosan-co-poly(maleic anhydride) (referred as Cs-MAH) matrix. Silanizing of montmorillonite is one of strategy to improve the interaction between montmorillonite and chitosan, consequently, the mechanical properties, tensile strength of composites contained 6 phr of sMMt improved 56.5% to chitosan. Moreover, the presence both MAH and sMMt on the comosites also reduced swelling degree and swelling area by 20.6% and 26.7%.

  12. Carbon nanotube/paraffin/montmorillonite composite phase change material for thermal energy storage.

    Science.gov (United States)

    Li, Min; Guo, Qiangang; Nutt, Steven

    2017-04-01

    A composite phase change material (PCM) comprised of organic montmorillonite (OMMT)/paraffin/grafted multi-walled nanotube (MWNT) is synthesized via ultrasonic dispersion and liquid intercalation. The microstructure of the composite PCM has been characterized to determine the phase distribution, and thermal properties (latent heat and thermal conductivity) have been measured by differential scanning calorimetry (DSC) and a thermal constant analyzer. The results show that paraffin molecules are intercalated in the montmorillonite layers and the grafted MWNTs are dispersed in the montmorillonite layers. The latent heat is 47.1 J/g, and the thermal conductivity of the OMMT/paraffin/grafted MWNT composites is 34% higher than that of the OMMT/paraffin composites and 65% higher than that of paraffin.

  13. Effect of milling time on the structure, particle size, and morphology of montmorillonite

    International Nuclear Information System (INIS)

    Abareshi, M.

    2017-01-01

    In the current research, effect of milling on the structure, particle size and morphology of montmorillonite was investigated. For this purpose, the montmorillonite was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the montmorillonite was milled using high energy planetary ball mill at different milling times (1-60 hours). After that, the structure, particle size and morphology of all samples were investigated by XRD, FTIR, SEM, and transmission electron microscopy. Results showed that the ball milling causes the particle size reduction of clay and separation of the clay layers. Moreover, ball milling increases the overall structural disorder and transforms the crystalline structure into an amorphous phase. Also, the morphology of clay particle changes from layered to aggregates of almost rounded particles after 60 hours of milling.

  14. Synthesis and Optical Properties of MnS–ZnS and MnS–CdS Nanoparticles in Montmorillonite.

    Science.gov (United States)

    Kabilaphat, Jirabhorn; Poosimma, Poonsuk; Khaorapapong, Nithima; Intachai, Sonchai; Ogawa, Makoto

    2017-02-01

    The incorporation of metal sulfide mixture, manganese sulfide and zinc sulfide (MnS–ZnS) or manganese sulfide and cadmium sulfide (MnS–CdS), in two types of montmorillonites (sodium montmorillonite and cetyltrimethylammonium modified montmorillonite) was investigated. The hybrids were characterized by powder X-ray diffraction, thermogravimetric-differential thermal analysis, transmission electron microscopy (TEM), and Raman, UV-visible and photoluminescence spectroscopies. The experimental evidences such as the expansion of the interlayer spaces and the presence of the absorption and photoluminescence due to MnS, ZnS and/or CdS revealed that the mixed metal sulfides formed in the interlayer space of montmorillonites. TEM images of the hybrids showed diskor plate-shaped nanoparticles with a mean diameter of ca. 2 nm. The increase of the luminescence intensities of the hybrids was assumed to be caused by quantum confinement effect in the interlayer space of montmorillonite.

  15. Waste Isolation Pilot Plant Materials Interface Interactions Test: Papers presented at the Commission of European Communities workshop on in situ testing of radioactive waste forms and engineered barriers

    International Nuclear Information System (INIS)

    Molecke, M.A.; Sorensen, N.R.

    1993-08-01

    The three papers in this report were presented at the second international workshop to feature the Waste Isolation Pilot Plant (WIPP) Materials Interface Interactions Test (MIIT). This Workshop on In Situ Tests on Radioactive Waste Forms and Engineered Barriers was held in Corsendonk, Belgium, on October 13--16, 1992, and was sponsored by the Commission of the European Communities (CEC). The Studiecentrum voor Kernenergie/Centre D'Energie Nucleaire (SCK/CEN, Belgium), and the US Department of Energy (via Savannah River) also cosponsored this workshop. Workshop participants from Belgium, France, Germany, Sweden, and the United States gathered to discuss the status, results and overviews of the MIIT program. Nine of the twenty-five total workshop papers were presented on the status and results from the WIPP MIIT program after the five-year in situ conclusion of the program. The total number of published MIIT papers is now up to almost forty. Posttest laboratory analyses are still in progress at multiple participating laboratories. The first MIIT paper in this document, by Wicks and Molecke, provides an overview of the entire test program and focuses on the waste form samples. The second paper, by Molecke and Wicks, concentrates on technical details and repository relevant observations on the in situ conduct, sampling, and termination operations of the MIIT. The third paper, by Sorensen and Molecke, presents and summarizes the available laboratory, posttest corrosion data and results for all of the candidate waste container or overpack metal specimens included in the MIIT program

  16. Effect of temperature on the crevice corrosion resistance of Ni-Cr-Mo alloys as engineered barriers in nuclear waste repositories

    International Nuclear Information System (INIS)

    Hornus, Edgard C.; Rodríguez, Martin A.

    2011-01-01

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly corrosive environments. Alloys 625, C-22, C-22HS and Hybrid-BC1 are considered among candidates as engineered barriers of nuclear repositories. The objective of the present work was to assess the effect of temperature on the crevice corrosion resistance of these alloys. The crevice corrosion re-passivation potential (E CO ) of the tested alloys was determined by the Potentiodynamic-Galvanostatic-Potentiodynamic (PD-GS-PD) method. Alloy Hybrid-BC1 was the most resistant to chloride-induced crevice corrosion, followed by alloys C-22HS, C-22 and 625. E CO showed a linear decrease with temperature. There is a temperature above which E CO does not decrease anymore, reaching a minimum value. This E CO value is a strong parameter for assessing the localized corrosion susceptibility of a material in a long term timescale, since it is independent of temperature, chloride concentration and geometrical variables such as crevicing mechanism, crevice gap and type of crevice formers. (author) [es

  17. FEBEX project: full-scale engineered barriers experiment for a deep geological repository for high level radioactive waste in crystalline host rock. Final report

    International Nuclear Information System (INIS)

    Alberdi, J.; Barcala, J. M.; Campos, R.; Cuevas, A. M.; Fernandez, E.

    2000-01-01

    FEBEX has the multiple objective of demonstrating the feasibility of manufacturing, handling and constructing the engineered barriers and of developing codes for the thermo-hydro-mechanical and thermo-hydro-geochemical performance assessment of a deep geological repository for high level radioactive wastes. These objectives require integrated theoretical and experimental development work. The experimental work consists of three parts: an in situ test, a mock-up test and a series of laboratory tests. The experiments is based on the Spanish reference concept for crystalline rock, in which the waste capsules are placed horizontally in drifts surround by high density compacted bentonite blocks. In the two large-scale tests, the thermal effects of the wastes were simulated by means of heaters; hydration was natural in the in situ test and controlled in the mock-up test. The large-scale tests, with their monitoring systems, have been in operation for more than two years. the demonstration has been achieved in the in situ test and there are great expectation that numerical models sufficiently validated for the near-field performance assessment will be achieved. (Author)

  18. Review of Studies of Clay Minerals as Significant Component of Potential Host Rocks or Engineering Barriers for Radioactive Waste Disposals Performed at Comenius University in Bratislava

    International Nuclear Information System (INIS)

    Peter, Uhlik; Vladimir, Sucha; Maria, Caplovicova; Igor, Stricek

    2013-01-01

    About 50 % of electric power is produced by nuclear power plants in Slovakia. In spite of the significant production of nuclear waste, Slovakia has not defined basic strategy of radioactive-waste isolation. However, some pilot projects and studies have been carried out. Five areas were determined as prospective sites for construction of deep geological repository (DGR). Two of them are situated in the south of Slovakia. Szecseny schlier (mixture of siltstones and Clay-stones) of Lucenec Formation (Egerian) is one of the most prospective host rocks from lithological, structural and spatial perspective. Besides the investigation of potential host rock for DGR the studies of bentonite properties as important part of engineering barriers for radioactive waste disposals were performed. Detailed mineral and structural analyses of smectites from the bentonitic material exposed to laboratory Mock-Up test were realised. Particular interest has been focused on interaction between Fe and smectites. Other field of interest is investigation of sorption of Cs and Sr on natural and modified bentonites, including irradiation. Purpose of this work is to present a short review of other studies done by our group with partial focusing to interaction of organic dye (Rhoda-mine 6G) with smectite that is connected with changes of layer charge after treatment; possibilities to measure preferential orientation of clays after compaction by TEM and to effort to use X-ray micro-tomography for inner structure of sediments. (authors)

  19. FEBEX project: full-scale engineered barriers experiment for a deep geological repository for high level radioactive waste in crystalline host rock

    Energy Technology Data Exchange (ETDEWEB)

    Alberid, J; Barcala, J M; Campos, R; Cuevas, A M; Fernandez, E [Ciemat. Madrid (Spain)

    2000-07-01

    FEBEX has the multiple objective of demonstrating the feasibility of manufacturing, handling and constructing the engineered barriers and of developing codes for the thermo-hydro-mechanical and thermo-hydro-geochemical performance assessment of a deep geological repository for high level radioactive wastes. These objectives require integrated theoretical and experimental development work. The experimental work consists of three parts: an in situ test, a mock-up test and a series of laboratory tests. The experiments is based on the Spanish reference concept for crystalline rock, in which the waste capsules are placed horizontally in drifts surround by high density compacted bentonite blocks. In the two large-scale tests, the thermal effects of the wastes were simulated by means of heaters; hydration was natural in the in situ test and controlled in the mock-up test. The large-scale tests, with their monitoring systems, have been in operation for more than two years. the demonstration has been achieved in the in situ test and there are great expectation that numerical models sufficiently validated for the near-field performance assessment will be achieved. (Author)

  20. Scoping calculation of nuclides migration in engineering barrier system for effect of volume expansion due to overpack corrosion and intrusion of the buffer material

    International Nuclear Information System (INIS)

    Yoshita, Takashi; Ishihara, Yoshinao; Ishiguro, Katsuhiko; Ohi, Takao; Nakajima, Kunihiko

    1999-11-01

    Corrosion of the carbon steel overpack leads to a volume expansion since the specific gravity of corrosion products is smaller than carbon steel. The buffer material is compressed due to the corrosive swelling, reducing its thickness and porosity. On the other hand, buffer material may be extruded into fractures of the surrounding rock and this may lead to a deterioration of the planned functions of the buffer, including retardation of nuclides migration and colloid filtration. In this study, the sensitivity analyses for the effect of volume expansion and intrusion of the buffer material on nuclide migration in the engineering barrier system are carried out. The sensitivity analyses were performed on the decrease in the thickness of the buffer material in the radial direction caused by the corrosive swelling, and the change in the porosity and dry density of the buffer caused by both compacting due to corrosive swelling and intrusion of buffer material. As results, it was found the maximum release rates of relatively shorter half-life nuclides from the outside of the buffer material decreased for taking into account of a volume expansion due to overpack corrosion. On the other hand, the maximum release rates increased when the intrusion of buffer material was also taking into account. It was, however, the maximum release rates of longer half-life nuclides, such as Cs-137 and Np-237, were insensitive to the change of buffer material thickness, and porosity and dry density of buffer. (author)

  1. Technical note 5. SR-Site Independent Modelling of Engineered Barrier Evolution and Coupled THMC. Contribution to the Initial Review Phase

    International Nuclear Information System (INIS)

    Benbow, Steven; Metcalfe, Richard; Watson, Claire; Bond, Alex

    2012-06-01

    This review has focussed mainly on the modelling of the Engineered Barrier System (EBS) evolution, which includes coupled thermal, hydraulic, mechanical and chemical (THMC) processes. Additionally, the role of the EBS in the wider safety case was reviewed, including its treatment in scenarios and its representation in conceptual models since this provided the motivation for the modelling work that was undertaken by SKB. The scope of the work described here was to: 1. Review relevant documents concerning SKB's modelling; and 2. Check one particular modelling area that was judged to be important, based on this review, with a limited set of independent modelling/calculations. The review covers the early resaturation and swelling / homogenisation of the buffer; the longer-term chemical evolution of the buffer and backfill, corrosion of the copper canister and the chemical and hydrogeological boundary conditions provided by the surrounding host rock. The reviewers consider that SKB's modelling of engineered barrier performance generally supports their conclusion that the barriers will perform as required. However, there remain issues that are not addressed and uncertainties that are not explored adequately by SKB's modelling. The thermo-hydro-mechanical modelling of buffer resaturation that is performed by SKB is based on demonstrating a fit to measurements from the in-situ Canister Retrieval Test (CRT) experiment. The modelling reproduces some of the experimental observations very well, but some key experimental measurements are not considered. In particular, investigation of the fit to the measured rates of water inflow, which are a critical factor controlling the rate at which the buffer will resaturate, is not given, Furthermore, the water supply boundary conditions imposed on the CRT are not considered to be representative of those that might be expected in repository conditions. From the information that it is presented it is therefore not possible to be confident

  2. FEBEX-DP. Dismantling the ''full-scale engineered barrier experiment'' after 18 years of operation at the Grimsel Test Site, Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Kober, Florian; Gaus, Irina [Nagra, Wettingen (Switzerland)

    2015-07-01

    The FEBEX experiment at the Grimsel Test Site (GTS) consists of an in-situ full-scale engineered barrier system (EBS) test for the disposal of high-level waste (HLW). It is performed under natural conditions in crystalline rock in which the canisters are placed horizontally in drifts and are surrounded by a clay barrier constructed of highly compacted bentonite blocks. A partial dismantling and sampling of the EBS was carried out during 2002. Heating of the FEBEX started in 1997 and since then a constant temperature of 100 deg C has been maintained, while the bentonite buffer has been slowly hydrating in a natural way. A total of 632 sensors in the bentonite barrier, the rock mass, the heaters and the service zone record temperature, water saturation, humidity, total pressure, displacement, and water pressure. The hydration pattern is relatively symmetric, with no major differences along the axis. Although the host rock is characterized by heterogeneities with zones of higher permeability, the resaturation process is driven by the suction of the bentonite rather than by the availability of water in the rock, especially in the early phase. After 17 years, the water content in the buffer close to the heater still continues to increase slowly. The hydraulic pore pressures in the buffer and the geosphere have practically stabilized. The total pressure in general continues to increase in most points into the buffer, where in some parts pressures of over 6 MPa are registered. The long monitoring phase and the partial dismantling in 2002 indicate that the EBS has largely performed as expected and the major processes and couplings affecting the buffer saturation during the initial thermal period identified prior to the start of the experiment have been confirmed. A comprehensive report documents and reviews the state of the FEBEX (Lanyon and Gaus, 2013). After 18 years of operation the experiment will be excavated and dismantled in 2015. The main objectives of the FEBEX

  3. Geophysical characterization of subsurface barriers

    International Nuclear Information System (INIS)

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier

  4. Thermodynamic of hydration of a Wyoming montmorillonite saturated with Ca, Mg, Na and K

    International Nuclear Information System (INIS)

    Vieillard, P.; Blanc, P.; Gailhanou, H.; Gaboreau, S.; Giffaut, E.

    2010-01-01

    Document available in extended abstract form only. In the context of a disposal within clayey formations (Callovo-Oxfordian argillite) or using clayey barriers, the assessment of the long-term behavior of clay materials by geochemical modeling, requires thermodynamic properties of clay minerals. The Thermochimie database has been created by ANDRA in 1996 in order to provide coherent thermodynamic data of many minerals of interests with regards to this context, such as clay minerals. However, the thermodynamic properties of clay minerals, which govern the stability of these minerals in solution are still poorly understood. Indeed, there is little experimental data available in the literature concerning the hydration of smectites. On the other hand, it is not possible to acquire all the experimental thermodynamic hydration properties of clay minerals involved in natural systems or likely to be in the implementation of a deep disposal. In this study, we propose a method to estimate the thermodynamic hydration properties of a clay mineral. By considering the following reaction: Smectite nm H 2 O Smectite (0 H 2 O) + nm H 2 O (l), the hydration of smectite is calculated from an equilibrium condition involving anhydrous and hydrous components in which nm is the maximal number of moles of water in the fully hydrated end-member. By using a solid-solution formalism, the variation of the hydration state of a smectite with temperature or [H 2 O] can be possible. Analysis of experimental data indicates that solid solutions of hydrous and anhydrous smectite components at 25 deg. C and 1 bar are not ideal but can be expressed in terms of regular solution theory by considering the excess molal enthalpy of mixing (Hxs), the excess molal entropy of mixing (Sxs) and excess molal Gibbs free energy of mixing (Gxs) for binary solid solutions of homologous hydrous and anhydrous smectite components expressed in terms of Margules parameters W1 and W2. A compilation of measurements of

  5. Corrosion resistance of cast irons and titanium alloys as reference engineered metal barriers for use in basalt geologic storage: a literature assessment

    International Nuclear Information System (INIS)

    Charlot, L.A.; Westerman, R.E.

    1981-07-01

    A survey and assessment of the literature on the corrosion resistance of cast irons and low-alloy titanium are presented. Selected engineering properties of cast iron and titanium are briefly described; however, the corrosion resistance of cast iron and titanium in aqueous solutions or in soils and their use in a basalt repository are emphasized. In evaluating the potential use of cast iron and titanium as structural barrier materials for long-lived nuclear waste packages, it is assumed that titanium has the general corrosion resistance to be used in relatively thin cross sections whereas the cost and availability of cast iron allows its use even in very thick cross sections. Based on this assumption, the survey showed that: The uniform corrosion of low-alloy titanium in a basalt environment is expected to be extremely low. A linear extrapolation of general corrosion rates with an added corrosion allowance suggests that a 3.2- to 6.4-mm-thick wall may have a life of 1000 yr. Pitting and crevice corrosion are not likely corrosion modes in basalt ground waters. It is also unlikely that stress corrosion cracking (SCC) will occur in the commercially pure (CP) titanium alloy or in palladiumor molybdenum-alloyed titanium materials. Low-alloy cast irons may be used as barrier metals if the environment surrounding the metal keeps the alloy in the passive range. The solubility of the corrosion product and the semipermeable nature of the oxide film allow significant uniform corrosion over long time periods. A linear extrapolation of high-temperature corrosion rates on carbon steels and corrosion rates of cast irons in soils gives an estimated metal penetration of 51 to 64 mm after 1000 yr. A corrosion allowance of 3 to 5 times that suggests that an acceptable cast iron wall may be from 178 to 305 mm thick. Although they cannot be fully assessed, pitting and crevice corrosion should not affect cast iron due to the ground-water chemistry of basalt

  6. Development of plasticised nano-biocomposites of poly(hydroxybutyrate-co-hydroxyvalerate)/montmorillonite organically modified (PHBV/OMMT)

    International Nuclear Information System (INIS)

    Correa, M.C.; Pollet, E.; Averous, L.; Agnell, J.A.M.; Nascente, P.A.P.

    2010-01-01

    Several studies have aimed to improve the properties of biopolymers by the incorporation of nano-sized fillers, such as organo-modified montmorillonite (OMMT), to form nano-biocomposites. The objective of this work is to investigate the influence of acetyl tributyl citrate (ATBC) plasticizer with PHBV/OMMT nano-biocomposites aiming at improving their behavior. The materials PHBV, OMMT (C30B), and ATBC were provided by PHB Industrial S/A (Brazil), Southern Clay Products (USA), and Scandiflex S/A (Brazil), respectively. In this study the processing parameters and the formulations were controlled, pursuing materials with good mechanical and barrier properties with high biodegradability and with greater ease of processing. The analysis of the results obtained by TGA, GPC, WAXS, DSC, mechanical properties, and biodegradability lead to the conclusion that the addition of plasticizer in nanobiocomposites improved processability and did not influence the state of nano-sized load dispersion. It can be concluded that the addition of plasticizer is a good alternative to the processability of nanocomposites of PHAs. (author)

  7. Effect of kaolinite and Ca-montmorillonite on the alleviation of soil water repellency

    Czech Academy of Sciences Publication Activity Database

    Dlapa, P.; Doerr, S. H.; Lichner, Ľ.; Šír, Miloslav; Tesař, Miroslav

    2004-01-01

    Roč. 50, č. 8 (2004), s. 358-363 ISSN 0370-663X R&D Projects: GA AV ČR IAA3042301; GA AV ČR IBS2060104 Keywords : water repellency * kaolinite * Ca-montmorillonite Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.379, year: 2004

  8. Properties and Semicrystalline Structure Evolution of Polypropylene/Montmorillonite Nanocomposites under Mechanical Load

    DEFF Research Database (Denmark)

    Stribeck, Norbert; Zeinolebadi, Ahmad; Ganjaee Sari, Morteza

    2012-01-01

    Small-angle X-ray scattering (SAXS) monitors tensile and load-cycling tests of metallocene isotactic polypropylene (PP), a blend of PP and montmorillonite (MMT), and two block copolymer compatibilized PP/MMT nanocomposites. Mechanical properties of the materials are similar, but the semicrystalline......%. Other results concern the evolution of Strobl’s block structure and void formation during tensile loading....

  9. Electrochemical and radiochemical material transport examinations in humate-containing montmorillonite a bentonite thin layers

    International Nuclear Information System (INIS)

    Antal, K.; Joo, P.

    1999-01-01

    Various humate-containing H-bentonite layers were investigated using 137 Cs ion transport and radio absorption measuring method. These processes can model radioactive contamination migration in soils exposed to acid rains. Experiment using montmorillonite and bentonite layers are discussed, and the results obtained with electrochemical and radioisotope absorption techniques are presented. (R.P.)

  10. Molecular Simulation Study of Montmorillonite in Contact with Variably Wet Supercritical Carbon Dioxide

    KAUST Repository

    Kadoura, Ahmad Salim; Nair, Arun Kumar Narayanan; Sun, Shuyu

    2017-01-01

    We perform grand canonical Monte Carlo simulations to study the detailed molecular mechanism of intercalation behavior of CO2 in Na-, Ca-, and Mg- montmorillonite exposed to variably hydrated supercritical CO2 at 323.15 K and 90 bar, The simulations

  11. On different photodecomposition behaviors of rhodamine B on laponite and montmorillonite clay under visible light irradiation

    KAUST Repository

    Wang, Peng; Cheng, Mingming; Zhang, Zhonghai

    2013-01-01

    In this study, laponite and montmorillonite clays were found to be able to decompose rhodamine B upon visible light irradiation (λ>420nm). Very interestingly, it was found that rhodamine B on laponite underwent a stepwise N-deethylation and its

  12. Study on intercalation of ionic liquid into montmorillonite and its property evaluation

    International Nuclear Information System (INIS)

    Takahashi, Chisato; Shirai, Takashi; Fuji, Masayoshi

    2012-01-01

    Present study report fabrication of a solid–liquid intercalated compound using montmorillonite and ionic liquid [IL; 1-Butyl-3-methylimidazolium tetrafluoroborate; ([BMIM][BF 4 ])]. The intercalation of IL into the interlayer of montmorillonite was revealed by swelling behavior measured by X-ray diffraction (XRD) and cation exchange capacity (CEC). The crystal swelling structure of intercalation compound was further evidenced by transmission electron microscope (TEM). From these results, the arrangement of [BMIM] + ions (cationic part of IL) into the unit layer were proposed. Furthermore, the montmorillonite showed electrical conductivity with the aid of IL. This demonstrates a successful attempt to fabricate a solid–liquid state nano-structure compound as possible transparent electrically conducting thin film. -- Highlights: ► Direct intercalation of ionic liquid into the montmorillonite was studied. ► The crystal swelling structure in liquid state was successfully characterized by TEM. ► We proposed the atomic arrangement of intercalated compound using ionic liquid. ► Ionic liquid is useful for fabricating an intercalated compound with electrical-conductivity.

  13. Microstructures and physical properties of "backfill" clays: comparison of residua and sedimentary montmorillonite clays

    Czech Academy of Sciences Publication Activity Database

    Přikryl, R.; Ryndová, T.; Boháč, J.; Weishauptová, Zuzana

    2003-01-01

    Roč. 23, 1-4 (2003), s. 149-156 ISSN 0169-1317 R&D Projects: GA AV ČR IAA2046101 Institutional research plan: CEZ:AV0Z3046908 Keywords : bentonite * montmorillonite-rich clay * hydrophysical properties Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.287, year: 2003

  14. Green Synthesis of Carvenone by Montmorillonite-Catalyzed Isomerization of 1,2-Limonene Oxide

    DEFF Research Database (Denmark)

    Nguyen, Thao-Tran Thi; Chau, Duy-Khiem Nguyen; Duus, Fritz

    2013-01-01

    Montmorillonite was considered as a good heterogeneous catalyst for the isomerization of 1,2-limonene oxide into car-venone under solvent-free condition. Both conventional heating and green activations were tested in this research. The microwave-assisted isomerization afforded carvenone in high...

  15. Polyaniline-sodium montmorillonite clay nanocomposites: effect of clay concentration on thermal, structural, and electrical properties

    Czech Academy of Sciences Publication Activity Database

    Kazim, Samrana; Ahmad, S.; Pfleger, Jiří; Pleštil, Josef; Joshi, Y. M.

    2012-01-01

    Roč. 47, č. 1 (2012), s. 420-428 ISSN 0022-2461 R&D Projects: GA MŠk 7E10040 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyaniline * conductive polymer * montmorillonite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.163, year: 2012

  16. Localization of cesium on montmorillonite surface investigated by frequency modulation atomic force microscopy

    Science.gov (United States)

    Araki, Yuki; Satoh, Hisao; Okumura, Masahiko; Onishi, Hiroshi

    2017-11-01

    Cation exchange of clay mineral is typically analyzed without microscopic study of the clay surfaces. In order to reveal the distribution of exchangeable cations at the clay surface, we performed in situ atomic-scale observations of the surface changes in Na-rich montmorillonite due to exchange with Cs cations using frequency modulation atomic force microscopy (FM-AFM). Lines of protrusion were observed on the surface in aqueous CsCl solution. The amount of Cs of the montmorillonite particles analyzed by energy dispersive X-ray spectrometry was consistent with the ratio of the number of linear protrusions to all protrusions in the FM-AFM images. The results showed that the protrusions represent adsorbed Cs cations. The images indicated that Cs cations at the surface were immobile, and their occupancy remained constant at 10% of the cation sites at the surface with different immersion times in the CsCl solution. This suggests that the mobility and the number of Cs cations at the surface are controlled by the permanent charge of montmorillonite; however, the Cs distribution at the surface is independent of the charge distribution of the inner silicate layer. Our atomic-scale observations demonstrate that surface cations are distributed in different ways in montmorillonite and mica.

  17. Calcium montmorillonite clay for the reduction of aflatoxin residues in milk and dairy products

    Science.gov (United States)

    In this study, dairy cows were treated with calcium montmorillonite clay (NovaSil Plus (NSP); BASF Corp., Ludwigshaven, Germany) in a replicated 5x5 Lati