WorldWideScience

Sample records for chalks

  1. Chalk as a reservoir

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    chalk intervals are to some extent cemented and cannot compact mechanically at realistic effective stresses and only deform elastically. All chalk intervals though, may react by fracturing to changes in shear stress. So where natural fractures are not prevalent, fractures may be generated hydraulically....... Fractures play a significant role in the production of hydrocarbons from chalk reservoirs....

  2. Chalk as a reservoir

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    Reservoir properties of chalk depend on the primary sediment composition as well as on subsequent diagenesis and tectonic events. Chalks of the North Sea almost exclusively have mudstone or wackestone texture. Microfossils may have retained their porosity where degree of diagenesis is low, or be......, and the best reservoir properties are typically found in mudstone intervals. Chalk mudstones vary a lot though. The best mudstones are purely calcitic, well sorted and may have been redeposited by traction currents. Other mudstones are rich in very fine grained silica, which takes up pore space and...... thus reduces porosity at the same time as it increases specific surface and thus cause permeability to be low. In the Central North Sea the silica is quartzitic. Silica rich chalk intervals are typically found in the Ekofisk and Hod formations. In addition to silica, Upper Cretaceous and Palæogene...

  3. Permeability prediction in chalks

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Prasad, Manika

    2011-01-01

    The velocity of elastic waves is the primary datum available for acquiring information about subsurface characteristics such as lithology and porosity. Cheap and quick (spatial coverage, ease of measurement) information of permeability can be achieved, if sonic velocity is used for permeability...... prediction, so we have investigated the use of velocity data to predict permeability. The compressional velocity fromwireline logs and core plugs of the chalk reservoir in the South Arne field, North Sea, has been used for this study. We compared various methods of permeability prediction from velocities....... The relationships between permeability and porosity from core data were first examined using Kozeny’s equation. The data were analyzed for any correlations to the specific surface of the grain, Sg, and to the hydraulic property defined as the flow zone indicator (FZI). These two methods use two...

  4. Less chalk more action

    Science.gov (United States)

    Mitriceski Andelkovic, Bojana; Jovic, Sladjana

    2016-04-01

    Less chalk more action Education should not be a mechanical system that operates according to the principles of the orders and implementation. Education should respect the basic laws of the develop and progress. Curiosity is the engine of achievement and children spontaneously and happily learn only if they get interested, if teacher wake up and stimulate their creativity and individuality. We would like to present classes that are realized as thematic teaching with several subjects involved: chemistry, geography, math, art and biology. Classes were organized for students at age from 10 to 13 years, every month during autumn and winter 2015. Better students identified themselves as teachers and presented peer education .Teachers were monitoring the process of teaching and help to develop links between younger and older students, where older students were educators to younger students. Also one student with special needs was involved in this activities and was supported by other students during the workshops The benefit from this project will be represented with evaluation marks. Evaluation table shows that group of ten students(age 10 to13 years) which are selected in October as children with lack of motivation for learning, got better marks, at the end of January , then they had it in the beginning of the semester.

  5. Ecologically acceptable flows in Chalk rivers

    OpenAIRE

    Acreman, Mike; Dunbar, Michael

    2010-01-01

    The term ‘Chalk rivers’ is used to describe all those water courses dominated by groundwater discharge from Chalk geology. Natural conditions and historical modification have generated an ecosystem, with rich and unique assemblages and with high value to society (e.g. SACs, SSSIs, visual amenity and fisheries. Chalk rivers are considered to be sensitive to hydrological and morphological change and there is concern that flood defence and land drainage schemes, catchment agriculture, urbanisati...

  6. Self Compacting Concrete with Chalk Filler

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

    2007-01-01

    Utilisation of Danish chalk filler has been investigated as a means to produce self compacting concrete (SCC) at lower strength levels for service in non aggressive environments. Stable SCC mixtures were prepared at chalk filler contents up to 60% by volume of binder to yield compressive strengths...

  7. Decommissioning Experience: Chalk River, Canada

    International Nuclear Information System (INIS)

    Full text: Atomic Energy of Canada Limited has reported that work has continued on the decommissioning of old structures on the Chalk River laboratory site. An environmental assessment was approved in 2006 for the decommissioning of the NRX reactor fuel bays (A and B). The regulator approved two work packages for the removal of water and the wooden structure over the bays. The A bays were cleaned as far as possible and were emptied in 2007. Decontamination work will continue. Sections of the B bays were filled with sand and other parts filled with water. NRX is currently in storage (i.e. a dormant state) with surveillance. (author)

  8. Elastic behaviour of North Sea chalk

    DEFF Research Database (Denmark)

    Gommesen, Lars; Fabricius, Ida Lykke; Mukerji, T.;

    2007-01-01

    We present two different elastic models for, respectively, cemented and uncemented North Sea chalk well-log data. We find that low Biot coefficients correlate with anomalously low cementation factors from resistivity measurements at low porosity and we interpret this as an indication of cementation......-saturated North Sea reservoir chalk. In the acoustic impedance–Poisson's ratio plane, we forecast variations in porosity and hydrocarbon saturation from their influence on the elastic behaviour of the chalk. The Gassmann model and the self-consistent approximation give roughly similar predictions of the effect of...... filtrate. The amplitude-versus-angle (AVA) response for the general North Sea sequence of shale overlying chalk is predicted as a function of porosity and pore-fill. The AVA response of both cemented and uncemented chalk generally shows a declining reflectivity coefficient versus offset and a decreasing...

  9. Reactor loops at Chalk River

    International Nuclear Information System (INIS)

    This report describes broadly the nine in-reactor loops, and their components, located in and around the NRX and NRU reactors at Chalk River. First an introduction and general description is given of the loops and their function, supplemented with a table outlining some loop specifications and nine simplified flow sheets, one for each individual loop. The report then proceeds to classify each loop into two categories, the 'main loop circuit' and the 'auxiliary circuit', and descriptions are given of each circuit's components in turn. These components, in part, are comprised of the main loop pumps, the test section, loop heaters, loop coolers, delayed-neutron monitors, surge tank, Dowtherm coolers, loop piping. Here again photographs, drawings and tables are included to provide a clearer understanding of the descriptive literature and to include, in tables, some specifications of the more important components in each loop. (author)

  10. The North Sea reservoir chalk characterization

    OpenAIRE

    Kallesten, Emanuela

    2015-01-01

    A significant amount of the hydrocarbon production in the North Sea is related to chalk reservoirs. Since 1969, the chalk play remains one of the most important oil sources in Norway. With the initial expected recovery factor 17%, development in technologies and methods contributed to a substantial increase in oil recovery to an approximately 40%. Much of the reserves in place are yet to be extracted, and secondary and tertiary recovery methods need to advance in order to mobilize the remaini...

  11. Chalk: composition, diagenesis and physical properties

    OpenAIRE

    Fabricius, Ida Lykke

    2007-01-01

    Chalk is a sedimentary rock of unusually high homogeneity on the scale where physical properties are measured, but the properties fall in wide ranges. Chalk may thus be seen as the ideal starting point for a physical understanding of rocks in general. Properties as porosity, permeability, capillary entry pressure, and elastic moduli are consequences of primary sediment composition and ofsubsequent diagenetic history as caused by microbial action, burial stress, temperature, and pore pressure....

  12. Subsidence and capillary effects in chalks

    OpenAIRE

    Delage, Pierre; Schroeder, Christian; Cui, Yu-Jun

    1996-01-01

    Based on the concepts of the mechanics of unsaturated soils where capillary phenomena arise between the wetting fluid (water) and the non-wetting one (air), the subsidence of chalks containing oil (non-wetting fluid) during water injection (wetting fluid) is analysed. It is shown that the collapse phenomenon of unsaturated soils under wetting provides a physical explanation and a satisfactory prediction of the order of magnitude of the subsidence of the chalk. The use of a well established co...

  13. Adsorption of hydrocarbons in chalk reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, L.

    1996-12-31

    The present work is a study on the wettability of hydrocarbon bearing chalk reservoirs. Wettability is a major factor that influences flow, location and distribution of oil and water in the reservoir. The wettability of the hydrocarbon reservoirs depends on how and to what extent the organic compounds are adsorbed onto the surfaces of calcite, quartz and clay. Organic compounds such as carboxylic acids are found in formation waters from various hydrocarbon reservoirs and in crude oils. In the present investigation the wetting behaviour of chalk is studied by the adsorption of the carboxylic acids onto synthetic calcite, kaolinite, quartz, {alpha}-alumina, and chalk dispersed in an aqueous phase and an organic phase. In the aqueous phase the results clearly demonstrate the differences between the adsorption behaviour of benzoic acid and hexanoic acid onto the surfaces of oxide minerals and carbonates. With NaCl concentration of 0.1 M and with pH {approx_equal} 6 the maximum adsorption of benzoic acid decreases in the order: quartz, {alpha}-alumina, kaolinite. For synthetic calcite and chalk no detectable adsorption was obtaind. In the organic phase the order is reversed. The maximum adsorption of benzoic acid onto the different surfaces decreases in the order: synthetic calcite, chalk, kaolinite and quartz. Also a marked difference in adsorption behaviour between probes with different functional groups onto synthetic calcite from organic phase is observed. The maximum adsorption decreases in the order: benzoic acid, benzyl alcohol and benzylamine. (au) 54 refs.

  14. Chalk Formations as Natural Barriers towards Radionuclide Migration

    DEFF Research Database (Denmark)

    Pedersen, Walther Batsberg; Carlsen, Lars; Jensen, Bror Skytte

    1985-01-01

    A series of chalk samples from the cretaceous formation overlying the Erslev salt dome have been studied in order to establish permeabilities, porosities, dispersion-, diffusion-, and sorption characteristics of the chalk. The chalk was found to be porous (∊≈0.4), however, of rather low permeabil...

  15. Microdeformation and subcritical cracking in chalk

    Science.gov (United States)

    Bergsaker, Anne; Dysthe, Dag Kristian

    2016-04-01

    Deformation processes in chalks, both in relation to changing pore fluids and stress conditions has been of great interest as chalk is an important reservoir rock for both hydrocarbons and ground water. Lately it has also gained interest as a potential reservoir rock for captured CO2. Chalks are composed of large amounts of biogenic calcite grains, the skeletal debris of marine microorganisms. Its deformation is highly time and stress dependent, and governed by a transition from distributed to localized deformation at the onset of yield, affected by mechanisms such as subcritical crack growth and pore collapse. We present a microdeformation rig which makes use of thermal expansion as a means of subjecting small samples to strictly controlled tensile stresses. High resolution imaging provides resolutions down to 0.5 micrometers, enabling study of pore scale processes during slow deformation. Examples of localized and distributed deformation are presented.

  16. Elastic behaviour of North Sea chalk

    DEFF Research Database (Denmark)

    Gommesen, Lars; Fabricius, Ida Lykke; Mukerji, T.;

    2007-01-01

    We present two different elastic models for, respectively, cemented and uncemented North Sea chalk well-log data. We find that low Biot coefficients correlate with anomalously low cementation factors from resistivity measurements at low porosity and we interpret this as an indication of cementation...... self-consistent approximation, which here represents the unrelaxed scenario where the pore spaces of the rock are assumed to be isolated, and the Gassmann theory, which assumes that pore spaces are connected, as tools for predicting the effect of hydrocarbons from the elastic properties of brine......-saturated North Sea reservoir chalk. In the acoustic impedance–Poisson's ratio plane, we forecast variations in porosity and hydrocarbon saturation from their influence on the elastic behaviour of the chalk. The Gassmann model and the self-consistent approximation give roughly similar predictions of the effect of...

  17. Adsorption Properties of Chalk Reservoir Materials

    DEFF Research Database (Denmark)

    Okhrimenko, Denis

    Understanding adsorption energetics and wetting properties of calcium carbonate surfaces is essential for developing remediation strategies for aquifers, improving oil recovery, minimising risk in CO2 storage and optimising industrial processes. This PhD was focussed on comparing the vapour....../gas adsorption properties of synthetic calcium carbonate phases (calcite, vaterite and aragonite) with chalk, which is composed of biogenic calcite (>98%). In combination with data from nanotechniques, the results demonstrate the complexity of chalk behavior and the role of nanoscale clay particles. The results...

  18. Late Maastrichtian chalk mounds, Stevns Klint, Denmark

    DEFF Research Database (Denmark)

    Anderskouv, Kresten; Damholt, Tove; Surlyk, Finn

    controlling the depositional thickness variation across a mound and thus mound growth pattern. Relatively long wave-length wavy-bedded chalk shows gentle convex-up geometries and would probably be described as sediment waves if recognized in seismic sections. The chalk waves were deposited under weaker......-member processes: those that were purely physical and related to the interaction between available grain sizes and hydrodynamics, and those that were largely biological and associated with benthic growth and sediment trapping mainly by bryozoans. The succession was deposited on the upper part of the flank of a 3...

  19. Late Maastrichtian chalk mounds, Stevns Klint, Denmark

    DEFF Research Database (Denmark)

    Anderskouv, Kresten; Damholt, Tove; Surlyk, Finn

    2007-01-01

    determine depositional thickness across a mound and thus mound growth pattern. Relatively long wavelength wavy-bedded chalk show gentle convex-up geometries and would probably be described as sediment waves if recognized in seismic sections. The chalk waves were deposited under weaker current velocities...... the depositional architecture indicates a complex and   dynamic environment. The depositional style seems to be controlled by the interplay and relative importance of two end-member processes; those that were purely physical and related to the interaction between available grain sizes and...

  20. Aquifer properties of the Chalk of England

    OpenAIRE

    MacDonald, Alan M.; Allen, David J

    2001-01-01

    Aquifer properties data from 2100 pumping tests carried out in the Chalk aquifer have been collated as part of a joint British Geological Survey/Environment Agency project. The dataset is highly biased: most pumping tests have been undertaken in valley areas where the yield of the Chalk is highest. Transmissivity values from measured sites give the appearance of log-normality, but are not truly log-normal. The median of available data is 540 m2/d and the 25th and 75th percentiles 190 m2/d and...

  1. Chalk aquifer study : permeability and fractures in the English Chalk : a review of hydrogeological literature

    OpenAIRE

    Allen, D J

    1995-01-01

    The purpose of this report is to provide a review of the hydrogeological literature concerning the hydraulically significant fractures in the Chalk aquifer in England. The review discusses only the effect of the fractures on the permeability of the aquifer; it does not address the question of storage, nor the properties of the matrix. The report charts the evolution of ideas regarding the nature, occurrence and causes of hydraulically significant fractures in the Chalk and atte...

  2. Poroelasticity of high porosity chalk under depletion

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2013-01-01

    The theory of poroelasticity for the elastic region below pore collapse by means of three different loading paths gives the possibility to compare the static and dynami-cally determined Biot coefficient for a set of experimental data with uniaxial loading on outcrop chalk performed with different...

  3. Slope failure of chalk channel margins

    DEFF Research Database (Denmark)

    Gale, A.; Anderskouv, Kresten; Surlyk, Finn;

    2015-01-01

    The importance of mass transport and bottom currents is now widely recognized in the Upper Cretaceous Chalk Group of Northern Europe. The detailed dynamics and interaction of the two phenomena are difficult to study as most evidence is based on seismic data and drill core. Here, field observations...

  4. Nickel adsorption on chalk and calcite

    DEFF Research Database (Denmark)

    Belova, Dina Alexandrovna; Lakshtanov, Leonid; Carneiro, J.F.;

    2014-01-01

    Nickel uptake from solution by two types of chalk and calcite was investigated in batch sorption studies. The goal was to understand the difference in sorption behavior between synthetic and biogenic calcite. Experiments at atmospheric partial pressure of CO2, in solutions equilibrated with calcite...

  5. Competitive sorption of organic contaminants in chalk

    Science.gov (United States)

    Graber, E. R.; Borisover, M.

    2003-12-01

    In the Negev desert, Israel, a chemical industrial complex is located over fractured Eocene chalk formations where transfer of water and solutes between fracture voids and matrix pores affects migration of contaminants in the fractures due to diffusion into the chalk matrix. This study tests sorption and sorption competition between contaminants in the chalk matrix to make it possible to evaluate the potential for contaminant attenuation during transport in fractures. Single solute sorption isotherms on chalk matrix material for five common contaminants ( m-xylene, ametryn, 1,2-dichloroethane, phenanthrene, and 2,4,6-tribromophenol) were found to be nonlinear, as confirmed in plots of Kd versus initial solution concentration. Over the studied concentration ranges, m-xylene Kd varied by more than a factor of 100, ametryn Kd by a factor of 4, 1,2-dichloroethane Kd by more than a factor of 3, phenanthrene Kd by about a factor of 2, and 2,4,6-tribromophenol Kd by a factor of 10. It was earlier found that sorption is to the organic matter component of the chalk matrix and not to the mineral phases (Chemosphere 44 (2001) 1121). Nonlinear sorption isotherms indicate that there is at least some finite sorption domain. Bi-solute competition experiments with 2,4,6-tribromophenol as the competitor were designed to explore the nature of the finite sorption domain. All of the isotherms in the bi-solute experiments are more linear than in the single solute experiments, as confirmed by smaller variations in Kd as a function of initial solution concentration. For both m-xylene and ametryn, there is a small nonlinear component or domain that was apparently not susceptible to competition by 2,4,6-tribromophenol. The nonlinear sorption domain(s) is best expressed at low solution concentrations. Inert-solvent-normalized single and bi-solute sorption isotherms demonstrate that ametryn undergoes specific force interactions with the chalk sorbent. The volume percent of phenanthrene

  6. Effect of Fluid Dynamic Viscosity on the Strength of Chalk

    DEFF Research Database (Denmark)

    Hedegaard, K.; Fabricius, Ida Lykke

    The mechanical strength of high porosity and weakly cemented chalk is affected by the fluid in the pores. In this study, the effect of the dynamic viscosity of non-polar fluids has been measured on outcrop chalk from Sigerslev Quarry, Stevns, Denmark. The outcome is that the measured strength of...... the chalk decreases with increasing dynamic viscosity. The proposed qualitative explanation is that pressure difference supports and enhances the generation of microscopic shear and tensile failures....

  7. Water in chalk reservoirs: 'friend or foe?'

    International Nuclear Information System (INIS)

    Most of the petroleum fields in the Norwegian sector of the North Sea are sandstone reservoirs; the oil and gas are trapped in different species of sandstone. But the Ekofisk Field is a chalk reservoir, which really challenges the operator companies. When oil is produced from chalk reservoirs, water usually gets in and the reservoir subsides. The subsidence may be expensive for the oil companies or be used to advantage by increasing the recovery rate. Since 60 per cent of the world's petroleum reserves are located in carbonate reservoirs, it is important to understand what happens as oil and gas are pumped out. Comprehensive studies at the Department of Petroleum Technology and Applied Geophysics at Stavanger University College in Norway show that the mechanical properties of chalk are considerably altered when the pores in the rock become saturated with oil/gas or water under different stress conditions. The processes are extremely complex. The article also maintains that the effects of injecting carbon dioxide from gas power plants into petroleum reservoirs should be carefully studied before this is done extensively

  8. Compaction of microfossil and clay-rich chalk sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2001-01-01

    The aim of this study was to evaluate the role of microfossils and clay in the compaction of chalk facies sediments. To meet this aim, chalk sediments with varying micro texture were studied. The sediments have been tested uniaxially confined in a stainless-steel compaction cell. The sediments ar...

  9. Compaction of North-sea chalk

    Science.gov (United States)

    Keszthelyi, Dániel; Dysthe, Dag Kristian; Jamtveit, Bjørn

    2014-05-01

    The Ekofisk field is the largest petroleum field in the Norwegian North Sea territory where oil is produced from chalk formations. Early stage of oil production caused considerable changes in pore fluid pressure which led to a reservoir compaction. Pore collapse mechanism caused by the dramatic increase of effective stress, which in turn was caused by the pressure reduction by hydrocarbon depletion, was early identified as a principal reason for the reservoir compaction (Sulak et al. 1991). There have been several attempts to model this compaction. They performed with variable success on predicting the Ekofisk subsidence. However, the most of these models are based on empirical relations and do not investigate in detail the phenomena involved in the compaction. In sake of predicting the Ekofisk subsidence while using only independently measurable variables we used a chalk compaction model valid on geological time-scales (Japsen et al. 2011) assuming plastic pore-collapse mechanism at a threshold effective stress level. We identified the phenomena involved in the pore collapse. By putting them in a sequential order we created a simple statistical analytical model. We also investigated the time-dependence of the phenomena involved and by assuming that one of the phenomena is rate-limiting we could make estimations of the compaction rate at smaller length-scales. By carefully investigating the nature of pressure propagation we could upscale our model to reservoir scale. We found that the predicted compaction rates are close enough to the measured rates. We believe that we could further increase accuracy by refining our model. Sulak, R. M., Thomas, L. K., Boade R. R. (1991) 3D reservoir simulation of Ekofisk compaction drive. Journal of Petroleum Technology, 43(10):1272-1278, 1991. Japsen, P., Dysthe, D. K., Hartz, E. H., Stipp, S. L. S., Yarushina, V. M., Jamtveit. (2011) A compaction front in North Sea chalk. Journal of Geophysical Research: Solid Earth (1978

  10. Chalk effect on PVC cross-linking under irradiation

    International Nuclear Information System (INIS)

    Effect of nonmodified and modified chalk on curing degree of polymer matrix was studied under-irradiation of PVC-compositions. Films of the compositions (100 mass part 7 PVC, 0-100 mas.part of chalk, 2.5 - lead sulfate, 1.5 - lead stearate and 0.3 - glycerin) were irradiated up to absorbed dose 0.1 MGy in an inert medium. Content of gel-fraction after boiling in THF was determined with use of IR spectroscopy. It was established, that intensive dehydrochlorination and polymer curing took place on chalk particle surface. Network fixed strongly chalk particles. However, chalk inhibited processes of dehydrochlorination and PVC curing, increasing amount of noncured PVC in polymer matrix

  11. Kolmanda aastatuhande piraadid / kommenteerinud Peter Chalk ja Gordan Van Hook

    Index Scriptorium Estoniae

    2009-01-01

    Piraatlusest Somaalia piirkonnas ja rahvusvahelistest dokumentidest piraatluse vastu võitlemiseks 21. sajandil. Kommenteerivad uurimiskeskuse RAND Corporation vanempoliitanalüütik Peter Chalk ja transpordikompanii Maersk Line innovatsiooni ja arenduse vanemdirektor Gordan Van Hook

  12. The invertebrate ecology of the Chalk aquifer in England (UK)

    Science.gov (United States)

    Maurice, L.; Robertson, A. R.; White, D.; Knight, L.; Johns, T.; Edwards, F.; Arietti, M.; Sorensen, J. P. R.; Weitowitz, D.; Marchant, B. P.; Bloomfield, J. P.

    2016-03-01

    The Chalk is an important water supply aquifer, yet ecosystems within it remain poorly understood. Boreholes (198) in seven areas of England (UK) were sampled to determine the importance of the Chalk aquifer as a habitat, and to improve understanding of how species are distributed. Stygobitic macro-invertebrates were remarkably common, and were recorded in 67 % of boreholes in unconcealed Chalk, although they were not recorded in Chalk that is concealed by low-permeability strata and thus likely to be confined. Most species were found in shallow boreholes (50 m) water tables, indicating that the habitat is vertically extensive. Stygobites were present in more boreholes in southern England than northern England (77 % compared to 38 %). Only two species were found in northern England compared to six in southern England, but overall seven of the eight stygobitic macro-invertebrate species found in England were detected in the Chalk. Two species are common in southern England, but absent from northern England despite the presence of a continuous habitat prior to the Devensian glaciation. This suggests that either they did not survive glaciations in the north where glaciers were more extensive, or dispersal rates are slow and they have never colonised northern England. Subsurface ecosystems comprising aquatic macro-invertebrates and meiofauna, as well as the microbial organisms they interact with, are likely to be widespread in the Chalk aquifer. They represent an important contribution to biodiversity, and may influence biogeochemical cycles and provide other ecosystem services.

  13. The Chalk River Tritium Extraction Plant

    International Nuclear Information System (INIS)

    The Chalk River Tritium Extraction Plant for removal of tritium from heavy water is described. Tritium is present in the heavy water from research reactors in the form of DTO at a concentration in the range of 1-35 Ci/kg. It is removed by a combination of catalytic exchange to transfer the tritium from DTO to DT, followed by cryogenic distillation to separate and concentrate the tritium to T2. The tritium product is reacted with titanium and packaged for transportation and storage as titanium tritide. The plant processes heavy water at a rate of 25 kg/h and removes 80% of the tritium and 90% of the protium per pass. Catalytic exchange is carried out in the liquid phase using a proprietary wetproofed catalyst. The plant serves two roles in the Canadian fusion program: it produces pure tritium for use in fusion research and development, and it demonstrates on an industrial scale many of the tritium technologies that are common to the tritium systems in fusion reactors (author)

  14. Inverse modeling of Chalk River block

    International Nuclear Information System (INIS)

    Within the framework of the international project HYDROCOIN, a block of fractured monzonitic gneiss within the facilities of Chalk River National Laboratories, Canada, was selected as a test case to study and develop strategies for the calibration and validation of groundwater flow models. Adopting a quasi-three dimensional formulation, the fractures were simulated by two-dimensional finite elements and the rock mass was simulated by strings of line elements. The models were calibrated using, first, steady-state data and, second, transient data. Model calibration involved both identification of model parameters and model structure. Model parameters were obtained by automatic estimation based on measures of the model response and prior information about the model parameters. Excellent agreement between measured and computed heads was obtained for the transient runs. However, such match was only fair in steady-state. Model Structures Identification criteria were used to rank the performance of several model structures. In the steady state the model structure identification criteria did not strongly support increasing the model complexity. However, it is also believed that the information content of the steady state data was quite poor. In contrast, the transient data being both more numerous and more informative than steady-state data, allowed the model structure identification criteria to suggest more complex models. The validation runs were performed on data corresponding to interference pump tests different from the ones used for calibration. The prediction errors in these runs were relatively small and consistent with the calibration uncertainty. Furthermore, the ranking of the models performances during validation runs was the same as the one obtained at the calibration stage, using Model Structure Identification Criteria. (author) 26 figs., 17 tabs., 39 refs

  15. Burial diagenesis of deep sea chalk as reflected in Biot's coefficient

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Alam, Mohammad Monzurul

    2013-01-01

    Burial diagenesis of chalk has been widely studied, but little agreement has been reached on by which mechanism porosity declines, and on how to calculate the deforming stress in the most informative way. Data from Ocean Drilling Program show that calcareous ooze transforms to chalk and chalk to ...

  16. Biot Critical Frequency Applied as Common Friction Factor for Chalk with Different Pore Fluids and Temperatures

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    Injection of water into chalk hydrocarbon reservoirs has lead to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. Water has a significant softening effect on elastic...... highly influenced by temperature....

  17. Influence of effective stress coefficient on mechanical failure of chalk

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Hjuler, M.L.;

    2012-01-01

    The Effective stress coefficient is a measure of how chalk grains are connected with each other. The stiffness of chalk may decrease if the amount of contact cements between the grains decreases, which may lead to an increase of the effective stress coefficient. We performed CO2 injection in chalk......, as this process could affect the grain contact cement. If this happens, the effective stress at the grain contacts in a reservoir will change according to the effective stress principle of Biot. In a p′-q space for failure analysis, we observed that a higher effective stress coefficient reduces the...... elastic region and vice versa. However, as the effective stress working on the rock decreases with increased effective stress coefficient, the reduction of elastic region will have less effect on pore collapse strength if we consider the change in the effective stress coefficient. This finding will help...

  18. Chemical and Mechanical processes during burial diagenesis of chalk

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine; Lind, Ida

    1998-01-01

    equal or larger influence on the textural development. In the chalk interval below, compaction is not the only porosity reducing agent but it has a larger influence on texture than concurrent recrystallization. Below 850 m grain-bridging cementation becomes important resulting in a lithified limestone......Burial diagenesis of chalk is a combination of mechanical compaction and chemical recrystallization as well as cementation. We have predicted the characteristic trends in specific surface resulting from these processes. The specific surface is normally measured by nitrogen adsorption but is here...... the Pacific, where a > 1 km thick package of chalk facies sediments accumulated from the Cretaceous to the present. In the upper 200-300 m the sediment is unconsolidated carbonate ooze, throughout this depth interval compaction is the principal porosity reducing agent, but recrystallization has an...

  19. Province of Ontario nuclear emergency plan part V - Chalk River

    International Nuclear Information System (INIS)

    The aim of Part 5 of the Provincial Nuclear Emergency Plan is to describe the measures that shall be undertaken to deal with a nuclear emergency caused by the Chalk River Laboratories. This plan deals mainly with actions at the Provincial level and shall by supplemented by the appropriate Municipal Plan. The Townships of Rolph, Buchanan, Wylie, and McKay, the Town of Deep River and the Village of Chalk River are the designated municipalities with respect to CRL. 2 tabs., 5 figs

  20. Initial field measurements on the Chalk River superconducting cyclotron

    International Nuclear Information System (INIS)

    The midplane magnetic field of the Chalk River superconducting cyclotron has been mapped in detail over the full operating range of 2.5 to 5 tesla. The field measuring apparatus is described and results given include measurements of the field stability, reproducibility and harmonic content. (author)

  1. Chalk porosity and sonic velocity versus burial depth

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Gommesen, Lars; Krogsbøll, Anette Susanne;

    2008-01-01

    Seventy chalk samples from four formations in the overpressured Danish central North Sea have been analyzed to investigate how correlations of porosity and sonic velocity with burial depth are affected by varying mineralogy, fluid pressure, and early introduction of petroleum. The results show th...

  2. Nano sized clay detected on chalk particle surfaces

    DEFF Research Database (Denmark)

    Skovbjerg, Lone; Hassenkam, Tue; Makovicky, Emil;

    2012-01-01

    that in calcite saturated water, both the polar and the nonpolar functional groups adhere to the nano sized clay particles but not to calcite. This is fundamentally important information for the development of conceptual and chemical models to explain wettability alterations in chalk reservoirs...

  3. Specific surface as a measure of burial diagenesis of chalk

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine; Lind, Ida; Mortensen, Jeanette

    ODP Leg 130, Site 807, in the western equatorial Pacific, penetrates a sequence of pelagic carbonate ooze, chalk and limestone. Compaction, recrystallisation and cementation of the carbonate matrix are diagenetic processes expected to be taking place more or less simultaneously. In order to assess...

  4. Quantitative 1D saturation profiles on chalk by NMR

    DEFF Research Database (Denmark)

    Olsen, Dan; Topp, Simon; Stensgaard, Anders;

    1996-01-01

    Quantitative one-dimensional saturation profiles showing the distribution of water and oil in chalk core samples are calculated from NMR measurements utilizing a 1D CSI spectroscopy pulse sequence. Saturation profiles may be acquired under conditions of fluid flow through the sample. Results reveal...

  5. Groundwater conversion areas in chalk in the southern Frankish Alps

    International Nuclear Information System (INIS)

    In order to collect hydro-geological data, chalk water marking was done and/or interpreted, water balances were produced, the contents tritium, oxygen 18, calcium, magnesium and the groundwater temperatures and electrolytic conductivity of the groundwater were examined and the dry weather drainage of individual sources was analysed. (orig./PW)

  6. Ekofisk chalk: core measurements, stochastic reconstruction, network modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, Saifullah

    2002-07-01

    This dissertation deals with (1) experimental measurements on petrophysical, reservoir engineering and morphological properties of Ekofisk chalk, (2) numerical simulation of core flood experiments to analyze and improve relative permeability data, (3) stochastic reconstruction of chalk samples from limited morphological information, (4) extraction of pore space parameters from the reconstructed samples, development of network model using pore space information, and computation of petrophysical and reservoir engineering properties from network model, and (5) development of 2D and 3D idealized fractured reservoir models and verification of the applicability of several widely used conventional up scaling techniques in fractured reservoir simulation. Experiments have been conducted on eight Ekofisk chalk samples and porosity, absolute permeability, formation factor, and oil-water relative permeability, capillary pressure and resistivity index are measured at laboratory conditions. Mercury porosimetry data and backscatter scanning electron microscope images have also been acquired for the samples. A numerical simulation technique involving history matching of the production profiles is employed to improve the relative permeability curves and to analyze hysteresis of the Ekofisk chalk samples. The technique was found to be a powerful tool to supplement the uncertainties in experimental measurements. Porosity and correlation statistics obtained from backscatter scanning electron microscope images are used to reconstruct microstructures of chalk and particulate media. The reconstruction technique involves a simulated annealing algorithm, which can be constrained by an arbitrary number of morphological parameters. This flexibility of the algorithm is exploited to successfully reconstruct particulate media and chalk samples using more than one correlation functions. A technique based on conditional simulated annealing has been introduced for exact reproduction of vuggy

  7. Horizontal wells up odds for profit in Giddings Austin chalk

    International Nuclear Information System (INIS)

    This paper reports on horizontal drilling in the Giddings field Austin chalk which has significantly improved average well recoveries and more than offset increased drilling costs. Although not the panacea originally promoted, horizontal drilling, in Giddings field, offers economic profits to the average investor. Economic analysis indicates that the typical investor is making money by earning returns in excess of market values. Field-wide development will, therefore, remain active unless oil prices or average well recoveries fall below $12/bbl or 112,000 bbl of oil equivalent (BOE), respectively. The application of technological innovation in the Giddings field may culminate in the drilling of over 2,000 horizontal Austin chalk wells, and has conceivably increased recoverable reserves by 400 million BOE

  8. Widespread methanotrophic primary production in lowland chalk rivers

    OpenAIRE

    Shelley, Felicity; Grey, Jonathan; Trimmer, Mark

    2014-01-01

    Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight geographically widespread methanotrophic carbon fixation within the gravel riverbeds of over 30 chalk...

  9. Widespread methanotrophic primary production in lowland chalk rivers.

    Science.gov (United States)

    Shelley, Felicity; Grey, Jonathan; Trimmer, Mark

    2014-05-22

    Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight geographically widespread methanotrophic carbon fixation within the gravel riverbeds of over 30 chalk rivers. In 15 of these, the potential for methane oxidation (methanotrophy) was also compared with photosynthesis. In addition, we performed detailed concurrent measurements of photosynthesis and methanotrophy in one large chalk river over a complete annual cycle, where we found methanotrophy to be active to at least 15 cm into the riverbed and to be strongly substrate limited. The seasonal trend in methanotrophic activity reflected that of the riverine methane concentrations, and thus the highest rates were measured in mid-summer. At the sediment surface, photosynthesis was limited by light for most of the year with heavy shading induced by dense beds of aquatic macrophytes. Across 15 rivers, in late summer, we conservatively calculated that net methanotrophy was equivalent to between 1% and 46% of benthic net photosynthetic production within the gravel riverbed, with a median value of 4%. Hence, riverbed chemosynthesis, coupled to the oxidation of methane, is widespread and significant in English chalk rivers. PMID:24695425

  10. Diagenetic Variations between Upper Cretaceous Outcrop and Deeply Buried Reservoir Chalks of the North Sea Area

    DEFF Research Database (Denmark)

    Hjuler, Morten Leth; Fabricius, Ida Lykke

    2007-01-01

    -particle connections and less altered particle shapes. The non-carbonate mineralogy of outcrop chalks is dominated by quartz, occasionally opal-CT and clinoptilolite, and the clay mineral smectite. In offshore chalks quartz still dominates, opal-CT has recrystallized into submicron-size quartz crystals and smectite...

  11. Current oil and gas production from North American Upper Cretaceous Chalks

    Energy Technology Data Exchange (ETDEWEB)

    Scholle, P.A.

    1977-01-01

    Production of oil and natural gas from North American chalks has increased significantly during the past five years. Chalk reservoirs have been discovered in the Gulf Coast in the Austin Group, Saratoga and Annona Chalks, Ozan Formation, Selma Group, Monroe gas rock, (an informal unit of Navarro age), and other Upper Cretaceous units. In the Western Interior, production has been obtained from the Cretaceous Niobrara and Greenhorn Formations. Significant discoveries of natural gas and gas condensate also have been made in the Upper Cretaceous Wyandot Formation on the Scotian Shelf of eastern Canada. All North American chalk units share a similar depositional and diagenetic history. The diagenetic history of a chalk is critical in determining its reservoir potential. All chalk has a stable composition (low-Mg calcite) and very high primary porosity. With subsequent burial, mechanical and chemical (solution-transfer) compaction can reduce or completely eliminate pore space. The degree of loss of primary porosity in chalk sections is normally a direct function of the maximum depth to which it has been buried. Pore-water chemistry, pore-fluid pressures, and tectonic stresses also influence rates of cementation. Oil or gas reservoirs of North American chalk fall into three main groups: 1. Areas with thin overburden and significant primary porosity retention. 2. Areas with thicker overburden but considerable fracturing. 3. Areas with thick overburden in which marine pore fluids have been retained.

  12. Dynamic up-scaling of relative permeability in chalk

    Energy Technology Data Exchange (ETDEWEB)

    Frykman, P.; Lindgaard, H.F.

    1997-12-31

    This paper describes how fine-scale geo-statistic reservoir models can be utilised for the up-scaling of two-phase flow properties, including both relative permeability and capillary pressure function. The procedure is applied to a North Sea chalk carbonate reservoir example, which is a high-porosity/low-permeability reservoir type. The study focuses on waterflooding as the main recovery scheme and for the given flow regime in the reservoir. The main purpose of the paper is to demonstrate the use of dynamic multi-step up-scaling methods in the preparation of detailed geological information for full field reservoir simulation studies. (au) EFP-96. 39 refs.

  13. Mortality among long-term Chalk River employees

    International Nuclear Information System (INIS)

    Mortality among Chalk River Nuclear Laboratory (CRNL) employees who died during employment or after retirement has been updated to 1985 December 31. Data in tabular form are presented for overall mortality for male and female employees, for the participants in the clean-up for the NRX and NRU reactor accidents and for a group of CRNL staff with lifetime accumulative doses in excess of 0.2 Sv. Data are also presented on the different types of cancer causing death among male employees. No statistically significant increases in cancer deaths were found in any of the groups analyzed. 25 refs

  14. Recent developments in waste characterization at Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    The waste characterization program (WCP) at Chalk River Nuclear Laboratories (CRNL) was initiated in 1982 to determine the physical, chemical and radiological properties of wastes intended for disposal in IRUS (Intrusion Resistant Underground Structure), a belowground vault to be constructed at CRNL. During the last year, work on the WCP has centered on determining the radionuclide inventories in candidate wastes for IRUS by gamma-ray monitoring and destructive radiochemical analysis. This paper presents the technical problems associated with monitoring various waste forms (geometry considerations, shielding problems, operating environment, etc.) and also presents details of the destructive radiochemical analysis program

  15. The Effect of Bacteria Penetration on Chalk Permeability

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Shapiro, Alexander; Nielsen, Sidsel Marie;

    , the spore forming Bacillus licheniformis 421 and the non-spore forming Pseudomonas putida K12, were used. The core plugs were Stevns Klint outcrop with initial permeability at 2-4 mD. The results revealed that bacteria were able to penetrate and to be transported through the chalk. Furthermore, a...... higher number of B. licheniformis was detected on the effluent compared with P. putida. However, in the experiment with B. licheniformis mainly spores were detected in the effluent. The core permeability decreased rapidly during injection of bacteria and a starvation period of 12 days did not allow the...... permeability to return to initial condition....

  16. Advanced waterflooding in chalk reservoirs: Understanding of underlying mechanisms

    DEFF Research Database (Denmark)

    Zahid, Adeel; Sandersen, Sara Bülow; Stenby, Erling Halfdan;

    2011-01-01

    pressure. We have also observed formation of a microemulsion phase between brine and oil with the increase in sulfate ion concentration at high temperature and pressure. In addition, sulfate ions can reduce interfacial tension (IFT) between oil and water. We propose that the decrease in viscosity and...... formation of a microemulsion phase could be the possible reasons for the observed increase in oil recovery with sulfate ions at high temperature in chalk reservoirs besides the mechanism of the rock wettability alteration, which has been reported in most previous studies....

  17. Origin of channel systems in the Upper Cretaceous chalk group of the Paris Basin

    DEFF Research Database (Denmark)

    Esmerode, E. V.; Surlyk, Finn

    2009-01-01

    presence of at least two distinct intra-chalk discordant reflections: a Top Santonian and a Mid-Campanian reflection. These reflections are in places associated with up to 120-m-deep channel-like structures trending preferentially N-S and NW-SE. The Mid-Campanian reflection is also sporadically associated......The Upper Cretaceous Chalk Group of the Anglo-Paris Basin is known to show wedging beds and channel-like features which disrupt the quietly deposited pelagic chalk that covered most of NW Europe in the Late Cretaceous. Two-D reflection seismic data from the Brie region, SE of Paris, show the...... collapse of the Cenozoic succession over the channel-like features as a result of intra-chalk dissolution. Both reflections correlate with indurated chalk layers and hardgrounds, and represent real unconformities. The Mid-Campanian reflection is furthermore associated with a stratigraphic hiatus. A...

  18. Improved Oil Recovery in Chalk. Spontaneous Imbibition affected by Wettability, Rock Framework and Interfacial Tension

    Energy Technology Data Exchange (ETDEWEB)

    Milter, J.

    1996-12-31

    The author of this doctoral thesis aims to improve the oil recovery from fractured chalk reservoirs, i.e., maximize the area of swept zones and their displacement efficiencies. In order to identify an improved oil recovery method in chalk, it is necessary to study wettability of calcium carbonate and spontaneous imbibition potential. The thesis contains an investigation of thin films and wettability of single calcite surfaces. The results of thin film experiments are used to evaluate spontaneous imbibition experiments in different chalk types. The chalk types were described detailed enough to permit considering the influence of texture, pore size and pore throat size distributions, pore geometry, and surface roughness on wettability and spontaneous imbibition. Finally, impacts of interfacial tension by adding anionic and cationic surfactants to the imbibing water phase are studied at different wettabilities of a well known chalk material. 232 refs., 97 figs., 13 tabs.

  19. Geochemical criteria for reservoir quality variations in chalk from the North Sea

    International Nuclear Information System (INIS)

    The influence of chalk geochemistry on petrophysical parameters determining porosity and permeability is investigated. The central well TWB-8 and eastern marginal well E-lx of the North Sea Tyra gas field were chosen. Drill core sections of Upper Maastrichtian and Danian chalk were selected. Chemical data on chalk samples were gathered by using X-ray fluorescence and instrumental neutron activation. Geochemical data are compared with the well-logging results. Geophysical logging suggests that there is reduced porosity in the Danian reservoir units LDP and UDT in both wells. The chalk drill core samples from the section with reduced porosity also show a lower Ca content. A high Si content is observed in these samples and a number of trace elements in chalk show a similar distribution with depth. Reservoir porosity may be estimated from the Si content of chalk. Chalk permeability may also be elements Al, Fe and Sc show the same trends as that for Si. Diagenetic changes in chalk also include clay minerals. The gas zone in TWB-8 is characterized by low contents of Na and Cl, i.e. lower water saturation is indicated. Low concentrations of rare earths in all chalk samples show a shale-normalized pattern that is characteristic of marine sediments laid down under oxic conditions. Some changes that occur with depth in the Ce anomaly may indicate a slight change in the depositional environment. The content of manganese continuously decreases with depth, from Danian (about 2000 ppm) to Maastrichtian strata (less than 200 ppm). In this respect, no other chemical element in chalk correlates with Mn. There is no indication as to which mineral or mineral phase one is likely to find in the element. (AB) 14 tabs., 49 ills., 147 refs

  20. Solute transport in the unsaturated zone of the Chalk

    International Nuclear Information System (INIS)

    Groundwater is a major source of public supply in England and Wales, where it meets about 30% of the demand. In some areas, particularly south-east England, it is the major source. Much concern has been expressed in recent years about the pollution of groundwater resources by nitrates, and the Water Research Centre has undertaken an extensive programme of drilling and sampling to determine the reason for the rise in nitrate levels and to assess future trends. To assist with the interpretation of field data, mechanisms of water and solute movement through the unsaturated zone have been investigated, and the Chalk, our major aquifer, has received particular attention. The dating of groundwater by tritium measurements has led to considerable speculation regarding flow processes in the Chalk, and the additional information gained from the nitrates investigations has led to the formulation of a flow model in which water and its solutes move at very different velocities. It has been deduced that in the unsaturated zone water moves downwards through the fissure system at about 0.7 m/d, while any solutes carried from the land surface move downwards at about 1 m/a. Laboratory experiments have yielded evidence in support of this hypothesis, though further research is needed before a comprehensive model of the flow mechanism can be established. A similar flow mechanism is expected to be operative in many other aquifers, and has important implications for groundwater pollution trends. (author)

  1. Performance of the Chalk River 36Cl AMS system

    International Nuclear Information System (INIS)

    The MP Tandem Injector of the Chalk River TASCC (Tandem Accelerator Superconducting Cyclotron) Facility is being used for 36Cl determinations in studies relating to hydrology and low and high level nuclear waste management. In addition to the accelerator, the computer controlled system comprises a multiple-sample, medium-current ion source, a high resolution injector, a low resolution velocity filter, a gas filled magnet and a Bragg-type particle detection/identification system. Accuracies of 5--10% have been achieved with good suppression of 36S and background levels as low as 5x10-1536Cl/Cl. Following a brief overview of the system, detailed results are presented for the performance of the gas-filled magnet and particle detector as well as for sources of background including ion source memory effects

  2. Advanced fuel cycle development at Chalk River Laboratories

    International Nuclear Information System (INIS)

    Chalk River Laboratories (CRL) has a mandate from the Canadian government to develop nuclear technologies that support generation of clean, safe energy. This includes the development of advanced nuclear fuel technologies to ensure sustainable energy sources for Canadians. The Fuel Development Branch leads CRL's development of advanced nuclear-reactor fuels. CRL capabilities include fuel fabrication development, irradiation testing, post-irradiation examination (PIE), materials characterization and code development (modeling). This paper provides an overview of these capabilities and describes recent development activities that support fuel-cycle flexibility in heavy-water reactors. This includes a review of irradiation testing and PIE for mixed-oxide, thoria, high-burnup UO2 and low-void reactivity fuels and burnable neutron absorbers. Fabrication development, material characterizations and modeling associated with these tests are also described. (author)

  3. Experience at Chalk River with a cw electron accelerator

    International Nuclear Information System (INIS)

    For several years a group at Chalk River has been studying the behaviour of structures operated in the cw mode under heavy beam loading. Three side-coupled structures, modelled on the LAMPF design, have been built and tests up to 50% beam loading have been performed on two of them. Control systems have been developed to regulate the disturbances arising from high average power in a multi-tank accelerator and procedures worked out to handle beam currents up to 20 mA at 4 MeV. A pancake-coupled structure has been designed for high power operation and results of low power tests on an aluminum model are presented. Tests at high power with a 50 mA electron beam are planned. (author)

  4. A parameter identifiability study of two chalk tracer tests

    Directory of Open Access Journals (Sweden)

    S. A. Mathias

    2006-08-01

    Full Text Available As with most fractured rock formations, Chalk is highly heterogeneous. Therefore, meaningful estimates of model parameters must be obtained at a scale comparable with the process of concern. These are frequently obtained by calibrating an appropriate model to observed concentration-time data from radially convergent tracer tests (RCTT. Arguably, an appropriate model should consider radially convergent dispersion (RCD and Fickian matrix diffusion. Such a model requires the estimation of at least four parameters. A question arises as to whether or not this level of model complexity is supported by the information contained within the calibration data. Generally modellers have not answered this question due to the calibration techniques employed. A dual-porosity model with RCD was calibrated to two tracer test datasets from different UK Chalk aquifers. A multivariate sensitivity analysis, which assumed only a priori upper and lower bounds for each model parameter, was undertaken. Rather than looking at measures of uncertainty, the shape of the multivariate objective function surface was used to determine whether a parameter was identifiable. Non-identifiable parameters were then removed and the procedure was repeated until all remaining parameters were identifiable.

    It was found that the single fracture model (SFM (which ignores mechanical dispersion obtained the best mass recovery, excellent model performance and best parameter identifiability in both the tests studied. However, there was no objective evidence suggesting that mechanical dispersion was negligible. Moreover, the SFM (with just two parameters was found to be good at approximating the Single Fracture Dispersion Model SFDM (with three parameters when different, and potentially erroneous parameters, were used. Overall, this study emphasises the importance of adequate temporal sampling of breakthrough curve data prior to peak concentrations, to ensure adequate characterisation of

  5. Biot Critical Frequency Applied as Common Friction Factor for Chalk with Different Pore Fluids and Temperatures

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    Injection of water into chalk hydrocarbon reservoirs has lead to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. Water has a significant softening effect on elastic...... we propose that the fluid effect on mechanical properties of highly porous chalk may be the result of liquid‐solid friction. Applying a different strain or stress rate is influencing the rock strength and needs to be included. The resulting function is shown to relate to the material dependent and...... rate independent b-factor used when describing the time dependent mechanical properties of soft rock or soils. As a consequence it is then possible to further characterize the material constant from the porosity and permeability of the rock as well as from pore fluid density and viscosity which is...

  6. Hydro-chemistry of paleontology of depression of Tajikistan in Late chalk period

    International Nuclear Information System (INIS)

    In this chapter authors made conclusion that on formation of clayey layers of upper chalk did influence following factors: shallow sea basin and its relatively small dimensions, climate aridity, relatively nearness nutrition areas, frequent change sea transgressions its recessions

  7. The role of alluvial valley deposits in groundwater–surface water exchange in a Chalk river

    OpenAIRE

    Abesser, Corinna; Shand, Paul; Gooddy, Daren; Peach, Denis

    2008-01-01

    To understand the processes of surface water–groundwater exchange in Chalk catchments, a detailed hydrogeochemical study was carried out in the Lambourn catchment in southeast England. Monthly monitoring of river flow and groundwater levels and water chemistry has highlighted a large degree of heterogeneity at the river-corridor scale. The data suggest an irregular connection between the river, the alluvial deposits, and the Chalk aquifer at the study site. The groundwaters in the alluvial gr...

  8. Change of Static and Dynamic Elastic Properties due to CO² Injection in North Sea Chalk

    OpenAIRE

    Alam, Mohammad Monzurul; Hjuler, M.L.; Christensen, H.F.; Fabricius, Ida Lykke

    2012-01-01

    Reservoir modeling and monitoring uses dynamic data for predicting and determining static changes. Dynamic data are achieved from the propagation velocity of elastic waves in rock while static data are obtained from the mechanical deformation. Reservoir simulation and monitoring are particularly importantin enhanced oil recovery by CO2 injection (CO2-EOR) in chalk as, chalk reservoirs are vulnerable to compaction under changed stress and pore fluid. From South Arne field, North Sea, we used E...

  9. Investigated Miscible CO2 Flooding for Enhancing Oil Recovery in Wettability Altered Chalk and Sandstone Rocks

    OpenAIRE

    Tabrizy, Vahid Alipour

    2012-01-01

    The thesis addresses oil recovery by miscible CO2 flooding from modified sandstone and chalk rocks. Calcite mineral surface is modified with stearic acid (SA) and asphaltene, and the silicate mineral surfaces are modified with N,N-dimethyldodecylamine (NN-DMDA) and asphaltene. The stability of adsorbed polar components in presence of SO4 2- and Mg2 + ions is also investigated. Recovery from sandstone cores is consistently lower than that from chalk cores saturated with...

  10. Persistent and emerging micro-organic contaminants in Chalk groundwater of England and France

    International Nuclear Information System (INIS)

    The Chalk aquifer of Northern Europe is an internationally important source of drinking water and sustains baseflow for surface water ecosystems. The areal distribution of microorganic (MO) contaminants, particularly non-regulated emerging MOs, in this aquifer is poorly understood. This study presents results from a reconnaissance survey of MOs in Chalk groundwater, including pharmaceuticals, personal care products and pesticides and their transformation products, conducted across the major Chalk aquifers of England and France. Data from a total of 345 sites collected during 2011 were included in this study to provide a representative baseline assessment of MO occurrence in groundwater. A suite of 42 MOs were analysed for at each site including industrial compounds (n = 16), pesticides (n = 14) and pharmaceuticals, personal care and lifestyle products (n = 12). Occurrence data is evaluated in relation to land use, aquifer exposure, well depth and depth to groundwater to provide an understanding of vulnerable groundwater settings. - Highlights: • Broad range of microorganics detected in Chalk groundwater in England and France. • Plasticisers, pesticides, BPA and THM detected at the highest concentrations. • Pesticides higher in outcrop Chalk, caffeine and BPA at concealed sites. • Occurrences show some relationship to land use, borehole depth and water level. - Broad screening reveals for the first time the extent of emerging microorganic pollution in Chalk groundwater sources across England and France

  11. A novel representation of chalk hydrology in a land surface model

    Science.gov (United States)

    Rahman, Mostaquimur; Rosolem, Rafael

    2016-04-01

    Unconfined chalk aquifers contain a significant portion of water in the United Kingdom. In order to optimize the assessment and management practices of water resources in the region, modelling and monitoring of soil moisture in the unsaturated zone of the chalk aquifers are of utmost importance. However, efficient simulation of soil moisture in such aquifers is difficult mainly due to the fractured nature of chalk, which creates high-velocity preferential flow paths in the unsaturated zone. In this study, the Joint UK Land Environment Simulator (JULES) is applied on a study area encompassing the Kennet catchment in Southern England. The fluxes and states of the coupled water and energy cycles are simulated for 10 consecutive years (2001-2010). We hypothesize that explicit representation for the soil-chalk layers and the inclusion of preferential flow in the fractured chalk aquifers improves the reproduction of the hydrological processes in JULES. In order to test this hypothesis, we propose a new parametrization for preferential flow in JULES. This parametrization explicitly describes the flow of water in soil matrices and preferential flow paths using a simplified approach which can be beneficial for large-scale hydrometeorological applications. We also define the overlaying soil properties obtained from the Harmonized World Soil Database (HWSD) in the model. Our simulation results are compared across spatial scales with measured soil moisture and river discharge, indicating the importance of accounting for the physical properties of the medium while simulating hydrological processes in the chalk aquifers.

  12. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    Science.gov (United States)

    Maruthi, Y. A.; Das, N. Lakshmana; Ramprasad, S.; Ram, S. S.; Sudarshan, M.

    2015-08-01

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk

  13. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    International Nuclear Information System (INIS)

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk

  14. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    Energy Technology Data Exchange (ETDEWEB)

    Maruthi, Y. A., E-mail: ymjournal2014@gmail.com [Associate professor, Dept of Environmental Studies, GITAM Institute of Science, GITAM University, Visakhapatnam, A.P (India); Das, N. Lakshmana, E-mail: nldas9@gmail.com [Professor, Dept of Physics, GITAM Institute of Science, GITAM University, Visakhapatnam, A.P (India); Ramprasad, S., E-mail: ramprasadsurakala@gmail.com [Research Scholar, Dept of Environmental science, GITAM Institute of Science, GITAM University, Visakhapatnam, A.P (India); Ram, S. S., E-mail: tracebio@gmail.com [Research Scholar, Dept of Trace element research, UGC-DAE Consortium Centre, Kolkata centre India (India); Sudarshan, M., E-mail: sude@alpha.iuc.res.in [Scientist-F, Dept of Trace element research, UGC-DAE Consortium Centre, Kolkata centre India (India)

    2015-08-28

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk.

  15. Impact of supercritical CO2 injection on petrophysical and rock mechanics properties of chalk: an experimental study on chalk from South Arne field, North Sea

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, Morten Leth; Christensen, Helle Foged;

    2011-01-01

    Changes in chalk due to EOR by injecting supercritical CO2 (CO2-EOR) can ideally be predicted by applying geophysical methods designed from laboratory-determined petrophysical and rock mechanics properties. A series of petrophysical and rock mechanics tests were performed on Ekofisk Formation and...

  16. Anthropogenic radionuclides in Ottawa River sediment near Chalk River Laboratories

    International Nuclear Information System (INIS)

    The Ottawa River has received nuclear reactor effluent from Chalk River Laboratories (CRL) for more than 60 years, including releases from a NRX accident in 1952. Recent interest in the potential impact of these historical releases and the possible need for remediation of a small region immediately downstream from the release point has led to comprehensive studies to assess risk to people and wildlife. In this paper, the results of an extensive survey of gamma-emitting anthropogenic radionuclides in Ottawa River sediment in the vicinity of CRL are presented. Anthropogenic radionuclides detected in Ottawa River sediment include 60Co, 94Nb, 137Cs, 152Eu, 154Eu, 155Eu and 241Am. Concentrations of all anthropogenic radionuclides decline rapidly with distance downstream of the process outfall, reaching stable concentrations about 2 km downstream. All of these radionuclides are found at some sites within 2 km upstream of the process outfall suggesting limited upstream transport and sedimentation. Comparison of anthropogenic radionuclides with several representative primordial radionuclides shows that with the exception of sites at the process outfall and within 2 km downstream of the process outfall, primordial radionuclide concentrations greatly exceed CRL derived anthropogenic radionuclide concentrations. Thus, over 60 years of radionuclide releases from operations at CRL have had little impact on radionuclide concentrations in Ottawa River sediment, except at a few sites immediately adjacent to the process outfall. (author)

  17. Effects of the restoration mortar on chalk stone buildings

    Science.gov (United States)

    Ion, R. M.; Teodorescu, S.; Ştirbescu, R. M.; Dulamă, I. D.; Şuică-Bunghez, I. R.; Bucurică, I. A.; Fierăscu, R. C.; Fierscu, I.; Ion, M. L.

    2016-06-01

    The monument buildings as components of cultural heritage are exposed to degradation of surfaces and chemical and mechanical degradation, often associated to soiling and irreversible deterioration of the building. In many conservative and restorative works, a cement-based mortar was used without knowing all the adverse effects of this material on the building. This paper deals with the study of the effects of natural cement used in restorative works in the particular case of the Basarabi-Murfatlar Churches Ensemble. Cement-based materials exposed to sulfate present in the chalk stone - gypsum (CaSO4.2H2O), can induce signs of deterioration, due to ettringite ([Ca3Al (OH)612H2O]2(SO4)32H2O) or thaumasite (Ca3[Si(OH)612H2O](CO3)SO4) formation. These phases contribute to strain within the material, inducing expansion, strength loss, spalling and severe degradation. Several combined techniques (XRD, EDXRF, ICP-AES, SEM, EDS, sulphates content, FT-IR and Raman analysis were carried out to put into evidence the effects of them on the building walls.

  18. Molten fuel moderator interaction program at Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Nitheanandan, T.; Kyle, G.; O' Connor, R.; Sanderson, D.B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2006-12-15

    The Canadian nuclear power generation industry, represented by the CANDU Owners Group (COG), has been funding an experimental program at Chalk River Laboratories (CRL) to study the interaction between molten material ejected from a fuel channel and the moderator. These experiments were designed to address one of the very low probability postulated accident events considered for CANDU Pressurized Heavy Water Reactors. The reactor consists of an array of horizontal fuel channels that contain the UO{sub 2}, nuclear fuel and high-temperature, high-pressure heavy water coolant. Under severely restricted flow blockage conditions, approaching 100% reduction of the flow area, postulated in a fuel channel, the temperature excursion could result in fuel melting, consequential failure of the fuel channel, and ejection of the molten fuel at high pressures into the heavy water moderator at near atmospheric pressure. In preparation for these tests, a chemical mixture called a thermite, that could produce a simulated molten fuel when ignited, was developed in partnership with Argonne National Laboratory (USA). Following this thermite development, two base-case reference tests were completed. The two base-case reference tests, with no molten material present, were performed in the Molten-Fuel Moderator-Interaction (MFMI) facility at CRL. Following the base-case reference tests, a high-pressure melt ejection test using prototypical corium was conducted. The objectives of this paper are to provide an overview of the MFMI program and present the results obtained from thermite development, base-case and melt ejection experiments. (author)

  19. Molten fuel moderator interaction program at Chalk River Laboratories

    International Nuclear Information System (INIS)

    The Canadian nuclear power generation industry, represented by the CANDU Owners Group (COG), has been funding an experimental program at Chalk River Laboratories (CRL) to study the interaction between molten material ejected from a fuel channel and the moderator. These experiments were designed to address one of the very low probability postulated accident events considered for CANDU Pressurized Heavy Water Reactors. The reactor consists of an array of horizontal fuel channels that contain the UO2, nuclear fuel and high-temperature, high-pressure heavy water coolant. Under severely restricted flow blockage conditions, approaching 100% reduction of the flow area, postulated in a fuel channel, the temperature excursion could result in fuel melting, consequential failure of the fuel channel, and ejection of the molten fuel at high pressures into the heavy water moderator at near atmospheric pressure. In preparation for these tests, a chemical mixture called a thermite, that could produce a simulated molten fuel when ignited, was developed in partnership with Argonne National Laboratory (USA). Following this thermite development, two base-case reference tests were completed. The two base-case reference tests, with no molten material present, were performed in the Molten-Fuel Moderator-Interaction (MFMI) facility at CRL. Following the base-case reference tests, a high-pressure melt ejection test using prototypical corium was conducted. The objectives of this paper are to provide an overview of the MFMI program and present the results obtained from thermite development, base-case and melt ejection experiments. (author)

  20. Climate change impacts on Chalk groundwater resources in eastern England

    Science.gov (United States)

    Hiscock, K.; Sandhu, C.; Conway, D.

    2004-05-01

    Climate change is expected to cause higher summer temperatures, less summer rainfall and more evapotranspiration in eastern England during this century, thereby increasing the stress on the underlying Chalk aquifer. This study, funded by the Tyndall Centre for Climate Change Research, investigates how future scenarios of climate change will influence groundwater availability in this major regional aquifer in terms of groundwater levels and river baseflow quantities. To examine these scenarios, a two-layer regional groundwater model was constructed with Visual MODFLOW for the Wensum and Nar river catchments in northern East Anglia. The UKCIP02 database for the `2020s High' and `2050s High and Low' gas emission scenarios was used to define selected future climate conditions. Historic recharge (1981-90) to the model is calculated separately, using the FAO approved method incorporating dominant land cover (crop type) and soil moisture content. Future recharge to the model is estimated by perturbing historic rainfall and evapotranspiration with scaling factors relating average monthly simulated future and baseline (1961-90) meteorological parameters. The model results predict an overall decrease in recharge for all three scenarios, with a maximum decrease in October of 62% and 91%, for both the 2020s High and 2050s High scenarios, respectively. The future drier summer periods are likely to cause a delay in the onset of recharge by a month, due to a corresponding overall increase in the evapotranspiration for all scenarios. Faced with these conditions, water companies are planning for less reliable groundwater resources within an overall risk-based approach to managing future water supply and demand.

  1. The Canadian HT dispersion experiment at Chalk River - June 1987

    International Nuclear Information System (INIS)

    A trace amount (3.54TBq) of tritiated hydrogen, HT, was released to the atmosphere at an experimental field at the Chalk River Laboratories on June 10, 1987 in order to study the environmental behaviour of HT. Experimental results showed that direct oxidation of HT in the atmosphere was small and confirmed that surface soils convert atmospheric HT to HTO. The HTO formed in the soil was slowly emitted to the atmosphere giving rise to the small concentrations of HTO observed in the air during the release and for a period of several weeks thereafter. HTO/HT ratios in air during the plume passage increased with downwind distance from a value of order 10-5 at 5 m to values between 4 x 10-4 and 8 x 10-4 at 400 m. Deposition velocities for HT to soil were in the range 10-4 to 10-3 m s-1. Rates of reemission of tritium from the soil to the atmosphere were typically a few percent per hour within one to two days of the release, declining to less than one percent per hour over two weeks. Tritium deposition velocities and reemission rates determined for soils in the field agreed well with laboratory measurements on field samples, and were similar in range to previous exposure chamber experiments carried out in various countries in the laboratory and field under non-winter conditions. Direct uptake of HT by vegetation was not detected. The time history of vegetation tritium was consistent with uptake of HTO from soil and atmosphere and with incorporation of tritium into the organically bound form through photosynthesis. The experiment provides an extensive data base suitable for the detailed evaluation of mathematical models describing the short range dispersion of tritium. The results indicate that the short range dose from a release of HT would be much less than the dose from an equivalent release of HTO

  2. Contaminated groundwater characterization at the Chalk River Laboratories, Ontario, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Schilk, A.J.; Robertson, D.E.; Thomas, C.W.; Lepel, E.A. [Pacific Northwest National Lab., Richland, WA (United States); Champ, D.R.; Killey, R.W.D.; Young, J.L.; Cooper, E.L. [Chalk River Labs., Chalk River, Ontario (Canada)

    1993-03-01

    The licensing requirements for the disposal of low-level radioactive waste (10 CFR 61) specify the performance objectives and technical requisites for federal and commercial land disposal facilities, the ultimate goal of which is to contain the buried wastes so that the general population is adequately protected from harmful exposure to any released radioactive materials. A major concern in the operation of existing and projected waste disposal sites is subterranean radionuclide transport by saturated or unsaturated flow, which could lead to the contamination of groundwater systems as well as uptake by the surrounding biosphere, thereby directly exposing the general public to such materials. Radionuclide transport in groundwater has been observed at numerous commercial and federal waste disposal sites [including several locations within the waste management area of Chalk River Laboratories (CRL)], yet the physico-chemical processes that lead to such migration are still not completely understood. In an attempt to assist in the characterization of these processes, an intensive study was initiated at CRL to identify and quantify the mobile radionuclide species originating from three separate disposal sites: (a) the Chemical Pit, which has received aqueous wastes containing various radioisotopes, acids, alkalis, complexing agents and salts since 1956, (b) the Reactor Pit, which has received low-level aqueous wastes from a reactor rod storage bay since 1956, and (c) the Waste Management Area C, a thirty-year-old series of trenches that contains contaminated solid wastes from CRL and various regional medical facilities. Water samples were drawn downgradient from each of the above sites and passed through a series of filters and ion-exchange resins to retain any particulate and dissolved or colloidal radionuclide species, which were subsequently identified and quantified via radiochemical separations and gamma spectroscopy. These groundwaters were also analyzed for anions

  3. Waste management activities at Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    Low-level radioactive waste-management operations at the Chalk River Nuclear Laboratories (CRNL) of Atomic Energy of Canada Limited began in 1946 and currently include waste processing and interim storage in engineered facilities built in unsaturated sandy overburden. In addition, an R and D program has been underway for about ten years directed at preparations for a transition from the current storage mode to one of permanent disposal for the management of about 5000 m3/a (as-generated volume) of low- and intermediate-level solid wastes generated on the CRNL site or shipped there from the nuclear industry, radioisotope producers and users across Canada. The first phase of the disposal program was the development and demonstration of selected waste processing methods for the volume reduction and immobilization of solid and liquid low-level wastes. This phase is now nearing completion with the construction, commissioning and operation of the CRNL Waste Treatment Centre. The Centre consists of a controlled-air incinerator for combustible solid and liquid wastes, ultrafiltration, reverse-osmosis, and evaporator systems for aqueous wastes, and wipe-film and ribbon-blender bituminizers for immobilizing the ash and waste concentrates. The second phase of the program is directed at further advances in waste characterization and processing, and at the development of two disposal concepts potentially suitable for the local geological situation - Intrusion-resistant shallow land burial and excavated rock cavities at shallow depth. Also included is the preparation of safety-assessment methodologies for the two concepts. The intent is to carry one or both disposal concepts through the constriction and operation of prototype facilities at CRNL as a qualified component of an evolving integrated disposal strategy for the current inventory and future arisings of wastes to be managed

  4. Managing Injected Water Composition To Improve Oil Recovery: A Case Study of North Sea Chalk Reservoirs

    DEFF Research Database (Denmark)

    Zahid, Adeel; Shapiro, Alexander; Stenby, Erling Halfdan;

    2012-01-01

    with the following injecting fluids: distilled water, brine with and without sulfate, and brine containing only magnesium ions. The total oil recovery, recovery rate, and interaction mechanisms of ions with rock were studied for different injecting fluids at different temperatures and wettability...... only the injection brine composition but also the formation water composition affected the oil recovery at high temperatures from the Stevns Klint chalk rock.......In recent years, many core displacement experiments of oil by seawater performed on chalk rock samples have reported SO42–, Ca2+, and Mg2+ as potential determining ions for improving oil recovery. Most of these studies were carried out with outcrop chalk core plugs. The objective of this study is...

  5. Full-waveform Inversion of Crosshole GPR Data Collected in Strongly Heterogeneous Chalk

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Zibar, Majken Caroline Looms; Nielsen, Lars;

    2015-01-01

    in an old chalk quarry in Eastern Denmark. Based on core data (including plug samples and televiewer logging data) collected in our four ~15-m-deep boreholes and results from previous related studies, it is apparent that the studied chalk is strongly heterogeneous. The upper ~7 m consist of variable coarse...... all the information contained in the data and is able to provide significantly improved images. Here, we apply full-waveform inversion to crosshole GPR data to image strong heterogeneity of the chalk related to changes in lithology and porosity. We have collected a crosshole tomography dataset...... address the importance of (i) adequate starting models, both in terms of the dielectric permittivity and the electrical conductivity, (ii) the estimation of the source wavelet, (iii) and the effects of data sampling density when imaging this rock type. Moreover, we discuss the resolution of the bedding...

  6. Biot Critical Frequency Applied to Description of Failure and Yield of Highly Porous Chalk with Different Pore Fluids

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    nature of dissolved salts have an effect.Water has a significant softening effect on elastic properties of chalk as calculated from wave data, and the softening increases with increasing critical frequency as defined by Biot. The critical frequency is the highest frequency where elastic wave propagation......Injection of water into chalk hydrocarbon reservoirs has led to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. In case of water-saturated samples, the concentration and...... data include chalk samples that were tested at temperatures from 20 °C to 130 °C with the following pore fluids: fresh water, synthetic seawater, glycol, and oil of varying viscosity. The critical frequency is calculated for each experiment. For each specimen, we calculate the thickness to the slipping...

  7. Correlation of carbon isotope events in the Danish Upper Cretaceous chalk

    Energy Technology Data Exchange (ETDEWEB)

    Schovsbo, N.H.; Rasmussen, Susanne L.; Sheldon, E. (Geological Survey of Denmark and Greenland, Copenhagen (Denmark)); Stemmerik, L. (Univ. of Copenhagen, Dept. of Geography and Geology, Copenhagen (Denmark))

    2008-07-15

    A high resolution carbon isotope (delta13C) profile through the upper Campanian to Maastrichtian chalk was recently completed based on material from the Stevns-1 core from the Stevns peninsula, eastern Denmark. The delta13C variation of marine carbonates essentially reflects global perturbations in the carbon cycle, i.e. the burial fluxes of carbonate carbon versus organic carbon. It is widely observed that the delta13C variation broadly tracks the eustatic sea-level curve, and that delta13C curves can be used for stratigraphic correlation. In the Stevns-1 core, a total of 29 notable isotope changes have been identified in the upper Campanian to Maastrichtian succession. In order to evaluate the stratigraphic significance of the isotope changes, the variation in delta13C values of the mid-Maastrichtian chalk from cores in eastern Denmark and the Danish North Sea, and from outcrops at Roerdal, northern Jylland has been examined. The selected interval is characterised by distinct chalk and marl cycles in the Stevns-1 and Karlslunde-1 cores and in the Roerdal quarry, where as a non-cyclic clean chalk is found in the M-10X well from the North Sea. In the Roerdal quarry, the chalk-marl unit spans the upper-lower Maastrichtian boundary in the Boreal brachiopod and belemnite stratigraphies. In Stevns-1 and Karlslunde-1 the chalk-marl unit was deposited during the younger part of nannofossil subzone UC20b. This paper presents preliminary results of a high-resolution study of carbon isotopes, carried out by the Geological Survey of Denmark and Greenland (GEUS) in co-operation with partners from the Department of Geography and Geology at the University of Copenhagen. This paper is a product of the Cretaceous Research Centre (CRC) at Geocenter Denmark. (au)

  8. Grain size distributions of chalk from image analysis of electron micrographs

    DEFF Research Database (Denmark)

    Røgen, Birte; Gommesen, Lars; Fabricius, Ida Lykke

    2001-01-01

    from image analysis due to rim effects inherent in backscatter images at high magnification. Thus, in order to obtain a consistent interpretation, we use total (He) porosity and insoluble residue as measured in the laboratory. We find that the volume density of larger grains (cross section larger than...... image analysis. The chalk is composed of a fine-grained matrix of nannofossils and predominantlycalcitic fossil debris with larger microfossil grains, but the chalk may also contain significant amounts of silica and siliciclastic clay. For image analysis, we used backscatter electron images of epoxy...

  9. Measuring and Modeling the Displacement of Connate Water in Chalk Core Plugs during Water Injection

    DEFF Research Database (Denmark)

    Korsbech, Uffe C C; Aage, Helle Karina; Andersen, Bertel Lohmann; Hedegaard, Kathrine; Springer, Niels

    2006-01-01

    The movement of connate water spiked with gamma emitting 22Na was studied during laboratory water flooding of oil saturated chalk from a North Sea oil reservoir. Using a one dimensional gamma monitoring technique is was observed that connate water is piled-up at the front of the injection water and...... forms a mixed water bank with almost 100% connate water in the front behind which a gradual transition to pure injection water occurs. This result underpins log interpretations from waterflooded chalk reservoirs. An ad hoc model was set up by use of the results, and the process was examined...

  10. Change of Static and Dynamic Elastic Properties due to CO² Injection in North Sea Chalk

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, M.L.; Christensen, H.F.;

    2012-01-01

    % non-carbonate. We studied difference in static and dynamic behavior. Furthermore, brine saturated data were compared with CO2 injected data to reveal the effect of supercritical CO2 injection in both static and dynamic elastic properties. We used strain gauges and LVDTs to measure static deformation....... We observed lower dynamic elastic modulus for chalk with higher non-carbonate content at porosities lower than 30%. In 30% porosity chalk, dynamic compressional and bulk modulus were found significantly higher than the static modulus. Static measurements with LVDT were found lowest. The effect of CO2...

  11. Rock physical aspects of CO{sub 2} injection in chalk

    Energy Technology Data Exchange (ETDEWEB)

    Alam, M.M.

    2011-04-15

    Impact of supercritical CO{sub 2} on the petrophysical and rock-mechanics properties of Ekofisk Formation and Tor Formation chalk from South Arne field, Danish North Sea, chalk was investigated. A series of laboratory experiments was performed on core material collected from the reservoir zone of the South Arne field in order to reveal the changes with respect to porosity, specific surface, pore stiffness, wettability, mineralogy and mechanical failure. In addition, a theoretical rock physical background was also established in order to be able to make sensible interpretation of laboratory data. Sound wave velocity was used as the central tool to study any change in petrophysical and rock mechanical properties. The main focus was to achieve a better understanding of effective stress coefficient (also known as Biot's coefficient); by means of which effective stress can be predicted more accurately. Independent theoretical studies were made on diagenesis, surface properties and stiffness of chalk and their relation with sonic velocity (or Biot's coefficient calculated from sonic velocity). The knowledge and experience from these studies was combined to achieve the main research objective of monitoring changes in hydrocarbon reservoirs in chalk due to CO{sub 2} injection. In order to understand the development of chalk from calcareous ooze and achieving pore stiffness, the diagenesis process of a sedimentary sequence from Kerguelen Plateau in the Indian Ocean was studied. The principal objective of the study was to explore how different porosity reduction mechanisms change the strength of these deep sea carbonate-rich sediments and how these mechanisms can be traced from the change in Biot's coefficient, alpha. In calcareous ooze, alpha was found close to one. Mechanical compaction reduces porosity, but only leads to a minor decrease in alpha. Recrystallization process renders particles smoother, but do not lead to reduction in alpha unless it gives

  12. ACE - an algebraic compiler and encoder for the Chalk River datatron computer

    International Nuclear Information System (INIS)

    ACE is a program written for the Chalk River Datatron (Burroughs 205) Computer to enable the machine to compile a program for solving a problem from instructions supplied by the user in a notation related much more closely to algebra than to the machine's own code. (author)

  13. Strength and Biot's coefficient for high-porosity oil- or water-saturated chalk

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling

    during hydrostatic loading. The hypothesis is that the Biot coefficient and the theory of poroelasticity may cover the fluid effect by including the increased fluid bulk modulus from oil to water. A high number of test results for both oil- and water-saturated high-porosity outcrop chalk show correlation...

  14. Ultrasonic velocities of North Sea chalk samples: influence of porosity, fluid content and texture

    DEFF Research Database (Denmark)

    Rogen, B.; Fabricius, Ida Lykke; Japsen, P.; Høier, Camilla Kruse; Mavko, G.; Pedersen, J.M.

    2005-01-01

    the South Arne Field than from the Dan Field for identical porosities. This difference may be due to textural differences between the chalk at the two locations because we observe that large grains (i.e. filled microfossils and fossil fragments) that occur more frequently in samples from the Dan Field...

  15. WIMS-CRNL: A user's manual for the Chalk River version of WIMS

    International Nuclear Information System (INIS)

    This report describes the preparation of the input for WIMS-CRNL, the Chalk River version of the WIMS lattice code. Also included are notes on the operation of the code, contents of the associated libraries, and the relation of WIMS-CRNL to other versions of the code

  16. Nuclear magnetic resonance and sound velocity measurements of chalk saturated with magnesium rich brine

    DEFF Research Database (Denmark)

    Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    The use of low field Nuclear Magnetic Resonance (NMR) to determine petrophysical properties of reservoirs has proved to be a good technique. Together with sonic and electrical resistivity measurements, NMR can contribute to illustrate the changes on chalk elasticity due to different pore water...

  17. The surface reactivity of chalk (biogenic calcite) with hydrophilic and hydrophobic functional groups

    Science.gov (United States)

    Okhrimenko, D. V.; Dalby, K. N.; Skovbjerg, L. L.; Bovet, N.; Christensen, J. H.; Stipp, S. L. S.

    2014-03-01

    The surface properties of calcium carbonate minerals play an important role in a number of industrial and biological processes. Properties such as wettability and adsorption control liquid-solid interface behaviour and thus have a strong influence on processes such as biomineralisation, remediation of aquifers and oil recovery. We investigated how two model molecules of different polarity, namely water and ethanol, interact with reservoir and outcrop chalk samples and we compared their behaviour with that of pure, inorganically precipitated calcite. Thermodynamic quantities, such as the work of wetting, surface energy and isosteric adsorption enthalpy, were determined from vapour adsorption isotherms. The chalks were studied fresh and after extraction of organic residues that were originally present in these samples. The work of wetting correlates with the amount of organic matter present in the chalk samples but we observed a fundamental difference between the adsorption properties of chalk and pure, inorganically precipitated calcite toward the less polar, ethanol molecule. Further analysis of the chemical composition of the organic matter extracted from the chalk samples was made by gas chromatography (GC-MS). Monitoring surface composition by X-ray photoelectron spectroscopy (XPS) before and after extraction of the organic material, and with atomic force microscopy (AFM), showed that nanometer sized clay crystals observed on the chalk particle surfaces could be an important part of the reason for the differences. Removal of the extractable portion of the hydrocarbons liberates adsorption sites that have different wetting properties than the rest of the chalk and these have an energy distribution that is similar to clays. Thus, the results exemplify the complexity of biogenic calcite adsorption behaviour and demonstrate that chalk wetting in drinking water aquifers as well as oil reservoirs is controlled partly by the nanoparticles of clay that have grown on the

  18. Seismic stratigraphy and sedimentary architecture of the Chalk Group in south-west Denmark

    DEFF Research Database (Denmark)

    Larsen, Connie; Ineson, Jon; Boldreel, Lars Ole

    2014-01-01

    The article focuses on a study undertaken by the Chalk Group on the western onshore region of the Danish Basin in Eastern Denmark related on the seismic stratigraphy and sedimentary architecture of the region. The study is undertaken through subdividing the northern North German Basin and the south...

  19. SNG-log in borehole P7 in Faxe Chalk Quarry

    DEFF Research Database (Denmark)

    Korsbech, Uffe C C

    1996-01-01

    A spectral natural gamma-ray log in a 190 m borehole in Faxe chalk quarry confirms that Danish bryozoan and corallic limestones contain very low levels of natural radioactivity. Due to the low content of natural radioactivity it has been possible to observe the influence from cosmic radiation. The...

  20. Nuclear Magnetic Resonance and Elastic Wave Velocity of Chalk Saturated with Brines Containing Divalent Ions

    DEFF Research Database (Denmark)

    Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    Nuclear magnetic resonance (NMR) has proven a good technique for measuring pore size distribution in reservoir rocks. The use of low field NMR together with sonic and electrical resistivity measurements, can contribute to illustrate the effect of adsorbing ions on chalk elasticity. NMR is useful...

  1. Nuclear magnetic resonance and sound velocity measurements of chalk saturated with magnesium rich brine

    DEFF Research Database (Denmark)

    Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    2013-01-01

    The use of low field Nuclear Magnetic Resonance (NMR) to determine petrophysical properties of reservoirs has proved to be a good technique. Together with sonic and electrical resistivity measurements, NMR can contribute to illustrate the changes on chalk elasticity due to different pore water...

  2. Using Raman spectroscopic imaging for non-destructive analysis of filler distribution in chalk filled polypropylene

    DEFF Research Database (Denmark)

    Boros, Evelin; Porse, Peter Bak; Nielsen, Inga;

    2016-01-01

    A feasibility study on using Raman spectral imaging for visualization and analysis of filler distribution in chalk filled poly-propylene samples has been carried out. The spectral images were acquired using a Raman spectrometer with 785 nm light source.Eight injection-molded samples with...

  3. Measuring and Modeling the Displacement of Connate Water in Chalk Core Plugs during Water Injection

    DEFF Research Database (Denmark)

    Korsbech, Uffe C C; Aage, Helle Karina; Andersen, Bertel Lohmann;

    2006-01-01

    The movement of connate water spiked with gamma emitting 22Na was studied during laboratory water flooding of oil saturated chalk from a North Sea oil reservoir. Using a one dimensional gamma monitoring technique is was observed that connate water is piled-up at the front of the injection water a...

  4. How burial diagenesis of chalk sediments controls sonic velocity and porosity

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2003-01-01

    , whereby IF increases and chalk forms. Rock mechanical tests show that when compaction requires more than in-situ stress, porosity reduction is arrested. During subsequent burial, crystals and pores grow in size as a consequence of the continuing recrystallization. ne lack of porosity loss during...

  5. Effective-stress-law behavior of Austin chalk rocks for deformation and fracture conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Warpinski, N.R.; Teufel, L.W.

    1994-08-01

    Austin chalk core has been tested to determine the effective law for deformation of the matrix material and the stress-sensitive conductivity of the natural fractures. For deformation behavior, two samples provided data on the variations of the poroelastic parameter, {alpha}, for Austin chalk, giving values around 0.4. The effective-stress-law behavior of a Saratoga limestone sample was also measured for the purpose of obtaining a comparison with a somewhat more porous carbonate rock. {alpha} for this rock was found to be near 0.9. The low {alpha} for the Austin chalk suggests that stresses in the reservoir, or around the wellbore, will not change much with changes in pore pressure, as the contribution of the fluid pressure is small. Three natural fractures from the Austin chalk were tested, but two of the fractures were very tight and probably do not contribute much to production. The third sample was highly conductive and showed some stress sensitivity with a factor of three reduction in conductivity over a net stress increase of 3000 psi. Natural fractures also showed a propensity for permanent damage when net stressed exceeded about 3000 psi. This damage was irreversible and significantly affected conductivity. {alpha} was difficult to determine and most tests were inconclusive, although the results from one sample suggested that {alpha} was near unity.

  6. Investigation of spore forming bacterial flooding for enhanced oil recovery in a North Sea chalk Reservoir

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Nielsen, Sidsel Marie; Eliasson Lantz, Anna;

    2015-01-01

    Little has been done to study microbial enhanced oil recovery (MEOR) in chalk reservoirs. The present study focuses on core flooding experiments designed to see microbial plugging and its effect on oil recovery. A pressure tapped core holder was used for this purpose. A spore forming bacteria Bac...

  7. Probing the intrinsically oil-wet surfaces of pores in North Sea chalk at subpore resolution

    DEFF Research Database (Denmark)

    Hassenkam, Tue; Skovbjerg, Lone Lindbæk; Stipp, Susan Louise Svane

    2009-01-01

    of the controlling factors for the effectiveness of water flooding, one of the most common methods to improve oil recovery in Chalk reservoirs. Understanding surface wetting and its variability at scales smaller than the pore dimension will potentially provide clues for more effective oil production...

  8. Late Maastrichtian chalk mounds, Stevns Klint, Denmark — Combined physical and biogenic structures

    Science.gov (United States)

    Anderskouv, Kresten; Damholt, Tove; Surlyk, Finn

    2007-08-01

    Upper Maastrichtian chalk exposed at the Sigerslev quarry, Stevns Klint, Denmark is characterized by wavy and mound-like bedding geometries outlined by bands of black flint nodules. Four morphological elements are recognized, although bedding geometries are highly variable: southward migrating mounds, eastward migrating mounds, chalk waves and evenly bedded chalk. The mounds are interpreted as having been formed by currents carrying fine-grained suspended sediment which was primarily deposited on the up-current mound flanks. Bryozoans were prolific on the up-current flanks and mound summits, which stabilized the mounds, increased bed roughness and the overall accumulation rate. However, accumulation thicknesses do not correlate consistently with bryozoan density. The bryozoans were therefore important for the formation of the mounds, but the distribution of bryozoans did not solely determine depositional thickness across a mound and thus mound growth pattern. Relatively long wavelength wavy-bedded chalk show gentle convex-up geometries and would probably be described as sediment waves if recognized in seismic sections. The chalk waves were deposited under weaker current velocities than those active during mound formation. The exposed succession is topped by more evenly bedded chalk which was deposited by quiet pelagic fall-out of fine-grained material. The whole succession was deposited on the upper part of the northern flank of a large WNW-ESE trending 3 km wide depositional ridge with an amplitude of 35-40 m formed by contour-parallel WNW-ward flowing bottom currents. The mounds may have been deposited by regional bottom currents, or by spill-over currents from the valley south of the large ridge. The succession was deposited during varying bottom current intensities and the depositional architecture indicates a complex and dynamic environment. The depositional style seems to be controlled by the interplay and relative importance of two end-member processes

  9. Laboratory measurements of the electrokinetic and electrochemical potential in chalk, with application to monitoring of saline intrusion in the UK chalk aquifer

    Science.gov (United States)

    MacAllister, D.; Jackson, M.; Butler, A. P.; Vinogradov, J.

    2012-12-01

    Saline intrusion is a global phenomenon affecting the availability of freshwater in coastal aquifers. The aim of this work is to investigate whether measurements of spontaneous potential (SP) can be used to monitor the intrusion of seawater into coastal aquifers, with specific application to the chalk aquifer near Brighton on the south coast of the UK. SP arises to maintain electrical neutrality when a separation of charge occurs due to gradients in pressure (electrokinetic or streaming potential), concentration (electrochemical potential) and temperature (thermoelectric potential). Concentration gradients are a characteristic feature of saline intrusion and may give rise to a measureable electrochemical potential (EC). In addition the electrokinetic potential (EK) will arise during abstraction and up-coning of the saline front. The intruding saline front could therefore be detected and monitored continuously, with SP measurements in boreholes and at the surface providing dense monitoring in space and time. To determine the likely magnitude of EK and EC signals during saline intrusion into the chalk aquifer, we measured EK and EC potentials in samples of Seaford chalk saturated with (i) natural, potable groundwater from the aquifer and (ii) seawater sampled from the English Channel. The EK coupling coefficient, which relates the gradient in voltage to the gradient in water pressure when the total current is zero, was found to be -60 mV/MPa in samples saturated with groundwater. In seawater saturated samples it was found to be only -1 mV/MPa. This result agrees with earlier work suggesting the EK potential is suppressed in high salinity environments due to a compressed electrical double layer. The EK coupling coefficient was negative in both cases, suggesting that the surface charge of Seaford chalk is negative when in contact with groundwater and seawater. The electrochemical experiments involved establishing a concentration gradient across the chalk samples

  10. Benthic macrofauna variations and community structure in Cenomanian cyclic chalk-marl from Southerham Grey Pit, SE England

    DEFF Research Database (Denmark)

    Lauridsen, Bodil Wesenberg; Gale, A. S.; Surlyk, Finn

    2009-01-01

    . The material comprises washing residues of 24 bulk samples collected from chalk and marl half-cycles. A total of 5055 invertebrate specimens were retrieved and referred to 68 species, forming the basis for the recognition of six guilds. In general, the fauna is more diverse in marl than in chalk, but...... clearly well adapted to both facies and thus to the fine grain size of the substrate rather than to lithology. The systematic difference in diversity between chalk and marl samples was possibly caused by long-term climatic and oceanographic changes and thus could represent a biological response to...

  11. Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea

    DEFF Research Database (Denmark)

    Røgen, Birte; Fabricius, Ida Lykke

    2002-01-01

    The permeability and capillary entry pressure of chalk reservoirs are controlled by their porosity and specific surface area. Measured permeabilities are in the range 0.025-5.3 mD and are successfully predicted by use of the Kozeny equation. In this paper we focus on the factors that control...... specific surface area. Fifty-nine Tor and Ekofisk Formation chalk samples from five North Sea chalk reservoirs were investigated. All contain quartz and clay minerals, most commonly kaolinite and smectite, with trace amounts of illite. The contents of calcite and quartz are inversely correlated and both...

  12. Porosity and sonic velocity depth trends of Eocene chalk in Atlantic Ocean: Influence of effective stress and temperature

    DEFF Research Database (Denmark)

    Awedalkarim, Ahmed; Fabricius, Ida Lykke

    2014-01-01

    We aimed to relate changes in porosity and sonic velocity data, measured on water-saturated Eocene chalks from 36 Ocean Drilling Program drill sites in the Atlantic Ocean, to vertical effective stress and thermal maturity. We considered only chalk of Eocene age to avoid possible influence of...... geological age on chalk compaction trends. For each depth, vertical effective stresses as defined by Terzaghi and by Biot were calculated. We used bottom-hole temperature data to calculate the time–temperature index of thermal maturity (TTI) as defined by Lopatin. Porosity and compressional wave velocity...

  13. NMR response of non-reservoir fluids in sandstone and chalk.

    Science.gov (United States)

    van der Zwaag, C H; Stallmach, F; Skjetne, T; Veliyulin, E

    2001-01-01

    Transverse (T2) NMR relaxation time at 2 MHz proton resonance frequency was measured on core plug samples from two different lithologies, sandstone and chalk, before and after exposure to selected drilling fluids. The results show that NMR signal response was significantly altered after displacing 50% of the original pore fluids, crude oil and water, by drilling fluid filtrate. Relaxation spectra of the rock samples invaded by water-based filtrate shift to significantly shorter T2-values. This shift yields an underestimation of the free-fluid volumes when selecting cut-off values of 33 ms and 100 ms for sandstone and chalk, respectively. In opposite, rock samples affected by oil-based filtrate respond with a signal indicating significantly larger free-fluid volumes than present before exposure. NMR-permeability calculated based on the Timur-Coates Free Fluid model altered in some cases by one order of magnitude. PMID:11445352

  14. Investigation of Lecturer's Chalk by X-Ray Florescence and Fast Neutron Activation Techniques

    International Nuclear Information System (INIS)

    Different samples of lecturer's chalk were studied, using X-ray florescence (XRF) and Fast Neutron Activation Analysis (FNAA) techniques to ensure the safety of its use. The K (X-rays) and the gamma-rays were measured, using Si(Li) and high-purity germanium (HPGe) spectrometers to detect and determine qualitatively and quantitatively the constituents of the studied samples. For the investigated bulk chalk samples, the XRF was used for determination the average neutron flux of 2×107 n/cm2 sec. The concentrations of the elements (Ca and small traces of Al, Fe, Mg and Si) were measured and their presence was confirmed by γ-ray, lifetime and/or XRF measurements.

  15. Seismic architecture of the Chalk Group from onshore reflection data in eastern Denmark

    DEFF Research Database (Denmark)

    Moreau, Julien; Anderskouv, Kresten; Boldreel, Lars Ole;

    The Upper Cretaceous-Danian chalk is well exposed in the 14 km long coastal cliff of Stevns Klint (eastern Denmark). The cliff is a world renowned for its spectacular exposure of the Cretaceous-Palaeogene boundary. Based on regional geological knowledge of the field and cores, the characteristics...... completed with the acquisition of an extensive set of subsurface data. The data include high resolution 2D multichannel seismics onshore and offshore, a seismic refraction profile, two entirely cored boreholes including wireline logs, GPR cross-hole tomography, thermographic analysis, etc. We intend...... to compile and merge the geological and geophysical datasets to investigate the variation of the Chalk Group properties and their signature in the subsurface. In this communication, the seismic reflection data are being analysed. Very high resolution litho-, bio- and cyclostratigraphy can be correlated...

  16. Gas compositions and processes in the unsaturated zone of the chalk and triassic sandstone aquifers, England

    International Nuclear Information System (INIS)

    Comparatively little is known about the nature of gas sources, sinks and transport in the unsaturated zone, yet this topic is of importance to a wide range of activities extending from agriculture to the construction industry. The composition of the unsaturated zone atmosphere in two different English aquifer types (Chalk and Triassic sandstone) was investigated by the construction of gas sampling boreholes with depths of up to 25 m. Monitoring took place at approximately 1-2 month intervals over 12-24 months. No significant seasonal variations in gas composition were noted. The following mean concentrations of gases was observed (Chalk, sandstone): N2 (77.7%, 77.7%), O2 (19.5%, 19.8%), CO2 (1.5%, 1.5%), N2O (4.2 ppmv, 2.4 ppmv), CH4 (0.1 ppmv, 0.3 ppmv), and δ13C-CO2 (-25.3 per mille, -19.9 per mille). The factor of 50 increase in CO2 reflects production from soil organic matter, supplemented in the sandstone by some CO2 from acidification or carbonate material. The decrease in O2 of little more than 1% absolute from atmospheric concentration indicates the persistence of oxidizing conditions in both unsaturated zones, and the relatively high concentrations of N2O therefore appear likely to have been derived from nitrification rather than denitrification. The limited magnitude of denitrification processes is further illustrated by N2/Ar and δ15N data. To understand better the rate of movement of gases in the unsaturated zone of a fissured aquifer, a tracer test using SF6 was carried out at the Chalk site. The results indicate a diffusion rate up to 103 times higher than that expected for the Chalk matrix alone. (author)

  17. Probing the intrinsically oil-wet surfaces of pores in North Sea chalk at subpore resolution

    OpenAIRE

    Hassenkam, T.; Skovbjerg, L. L.; Stipp, S. L. S.

    2009-01-01

    Pore surface properties control oil recovery. This is especially true for chalk reservoirs, where pores are particularly small. Wettability, the tendency for a surface to cover itself with fluid, is traditionally defined by the angle a droplet makes with a surface, but this macroscopic definition is meaningless when the particles are smaller than even the smallest droplet. Understanding surface wetting, at the pore scale, will provide clues for more effective oil recovery. We used a special m...

  18. Overview of research in physics and health sciences at the Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    Toxicology research was a logical extension of existing program at Chalk River. Research in radiotoxicology has been going on there since the early forties. An overview of the existing physics and health sciences research programs operating at the Research Company of Atomic Energy of Canada Limited was presented. Programs in nuclear physics, heavy ion nuclear physics, astrophysical neutrino physics, condensed matter physics, fusion, biology, dosimetry, and environmental sciences were briefly described. In addition, a description of the research company organization was provided

  19. Rock physics interpolation Used for velocity modeling of chalks: Ontong Java plateau example

    OpenAIRE

    Saberi, Mohammad Reza; Johansen, Tor Arne; Sælen, Gunnar

    2010-01-01

    Chalks are pelagic carbonate sediments that are deposited in deep-water environments. Their elastic behaviour is controlled by a combination of depositional conditions and subsequent diagenesis. In this paper, we incorporate geological information into rock physics modeling by constraining the pore structure (aspect ratio) variability. The strategy is to define a pore-model that reflects lithology, porosity and velocity. Then, a background velocity cube is constructed based on inf...

  20. Investigated Miscible CO2 Flooding for Enhancing Oil Recovery in Wettability Altered Chalk and Sandstone Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Tabrizy, Vahid Alipour

    2012-07-01

    The thesis addresses oil recovery by miscible CO2 flooding from modified sandstone and chalk rocks. Calcite mineral surface is modified with stearic acid (SA) and asphaltene, and the silicate mineral surfaces are modified with N,N-dimethyldodecylamine (NN-DMDA) and asphaltene. The stability of adsorbed polar components in presence of SO4 2- and Mg2 + ions is also investigated. Recovery from sandstone cores is consistently lower than that from chalk cores saturated with the same oil and flooded with CO2 at all miscible flooding conditions. This may be due to the larger permeability contrasts in sandstone cores, which promote the fingering phenomenon. Miscible CO2 flooding for chalk and sandstone cores with distilled water, as initial water saturation, shows also lower oil recovery than cores saturated with different ions. At higher miscible flooding conditions, higher oil recovery is obtained. However, presence of light components (such as C1 or C3) in oil reduced the recovery. Oil recovery in presence of methane (C1) is lower than that in presence of methane and propane (C1/C3). A ternary diagram was constructed in order to understand the CO2 flooding mechanism(s) at the different flooding conditions and in presence of light components. The side effect of the flooding with CO2 is the probability for asphaltene deposition. An approach based on solubility parameter in the liquid, is used to assess the risk for asphaltene deposition during CO2 miscible flooding. The light components (C1/C3) and higher flooding conditions enhanced the risk for asphaltene instability. It is also shown higher amount of asphaltene deposition in chalk cores than that in sandstone cores at similar miscibility conditions.(au)

  1. Palaeo-ages of groundwaters in a fissured chalk aquifer, United Kingdom

    International Nuclear Information System (INIS)

    The Chalk aquifer in southeast England has a classic dual-porosity structure, with bulk advection occurring primarily in fractures/fissures, and largely immobile storage in the highly porous matrix blocks. For pumped samples, estimates of groundwater residence times using traditional geochemical correction models with 14C-dating, and assuming that ages reflect mobile fissure water signatures, indicate late-glacial recharge (≥25ka BP, pre-dating the Last Glacial Maximum (LGM) in the UK c.18 ka BP) for groundwaters in the centre of the basin. Cooler recharge temperatures than for modem waters evidenced in environmental isotopic (δ2H, δ18O) and dissolved noble gas (Ne, Ar, Kr, Xe) contents confirm their palaeowater status. However, hydraulic age estimates for transit times from recharge are much younger (tens of years). Closer consideration of solute transport in the Chalk allows reconciliation of these apparently discordant ages. It is argued that, on the regional aquifer scale, environmental tracers in the fissured Chalk move as though in an Equivalent Porous Medium (EPM), with significant tracer retardation due to sorption and/or matrix diffusion effects. Downgradient trends in δ18O and noble gases as independent tracers of past climatic changes can then be used to further constrain the groundwater ages better than for 14C-dating alone. This approach points to a significant revision of groundwater ages in the aquifer; all ages are seen to reflect post-glacial recharge having occurred ≤13 ka BP. An important consequence of this revision is that it is suggested that traditional geochemical models potentially undercorrect for the full effect of hydrodynamic processes on tracer ages in fissured porous media like the Chalk. (author)

  2. Biot critical frequency applied as common friction factor for pore collapse and failure of chalk with different pore fluids and temperatures

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke; Foged, Niels Nielsen

    2011-01-01

    A fluid effect toward higher strengths for oil-saturated chalk compared with water-saturated chalk has previously been identified and labeled the "water-weakening phenomenon," but has not been further characterized physically. The hypothesis of this paper is that the Biot critical frequency with ...... present a new test series on Stevns chalk with unconfined compression and Brazilian strength results. Copyright © 2011 Society of Petroleum Engineers....

  3. Late Cretaceous (late Campanian-Maastrichtian) sea-surface temperature record of the Boreal Chalk Sea

    Science.gov (United States)

    Thibault, Nicolas; Harlou, Rikke; Schovsbo, Niels H.; Stemmerik, Lars; Surlyk, Finn

    2016-02-01

    The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr) sea-surface temperature (SST) changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark), tied to an astronomical timescale of the late Campanian-Maastrichtian (74 to 66 Ma). Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian-Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  4. Late Cretaceous (Late Campanian–Maastrichtian sea surface temperature record of the Boreal Chalk Sea

    Directory of Open Access Journals (Sweden)

    N. Thibault

    2015-11-01

    Full Text Available The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr sea-surface temperature (SST changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark, tied to an astronomical time scale of the late Campanian–Maastrichtian (74 to 66 Myr. Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian–Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  5. Late Cretaceous (Late Campanian-Maastrichtian) sea surface temperature record of the Boreal Chalk Sea

    Science.gov (United States)

    Thibault, N.; Harlou, R.; Schovsbo, N. H.; Stemmerik, L.; Surlyk, F.

    2015-11-01

    The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr) sea-surface temperature (SST) changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark), tied to an astronomical time scale of the late Campanian-Maastrichtian (74 to 66 Myr). Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian-Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  6. The effect of divalent ions on the elasticity and pore collapse of chalk evaluated from compressional wave velocity and low-field Nuclear Magnetic Resonance (NMR)

    DEFF Research Database (Denmark)

    Katika, Konstantina; Addassi, Mouadh; Alam, Mohammad Monzurul;

    2015-01-01

    The effects of divalent ions on the elasticity and the pore collapse of chalk were studied through rock-mechanical testing and low-field Nuclear Magnetic Resonance (NMR) measurements. Chalk samples saturated with deionized water and brines containing sodium, magnesium, calcium and sulfate ions were...

  7. High resolution microgravity investigations for the detection and characterisation of subsidence associated with abandoned, coal, chalk and salt mines

    Energy Technology Data Exchange (ETDEWEB)

    Styles, P.; Toon, S.; Branston, M.; England, R. [Keele Univ., Applied And Environmental Geophysics Group, School of Physical and Geographical Sciences (United Kingdom); Thomas, E.; Mcgrath, R. [Geotechnology, Neath (United Kingdom)

    2005-07-01

    The closure and decay of industrial activity involving mining has scarred the landscape of urban areas and geo-hazards posed by subsurface cavities are ubiquitous throughout Europe. Features of concern consist of natural solution cavities (e.g. swallow holes and sinkholes in limestone gypsum and chalk) and man-made cavities (mine workings, shafts) in a great variety of post mining environments, including coal, salt, gypsum, anhydrite, tin and chalk. These problems restrict land utilisation, hinder regeneration, pose a threat to life, seriously damage property and services and blight property values. This paper outlines the application of microgravity techniques to characterise abandoned mining hazard in case studies from Coal, Chalk and Salt Mining environments in the UK. (authors)

  8. High resolution microgravity investigations for the detection and characterisation of subsidence associated with abandoned, coal, chalk and salt mines

    International Nuclear Information System (INIS)

    The closure and decay of industrial activity involving mining has scarred the landscape of urban areas and geo-hazards posed by subsurface cavities are ubiquitous throughout Europe. Features of concern consist of natural solution cavities (e.g. swallow holes and sinkholes in limestone gypsum and chalk) and man-made cavities (mine workings, shafts) in a great variety of post mining environments, including coal, salt, gypsum, anhydrite, tin and chalk. These problems restrict land utilisation, hinder regeneration, pose a threat to life, seriously damage property and services and blight property values. This paper outlines the application of microgravity techniques to characterise abandoned mining hazard in case studies from Coal, Chalk and Salt Mining environments in the UK. (authors)

  9. Response of invertebrates from the hyporheic zone of chalk rivers to eutrophication and land use.

    Science.gov (United States)

    Pacioglu, Octavian; Moldovan, Oana Teodora

    2016-03-01

    Whereas the response of lotic benthic macroinvertebrates to different environmental stressors is a widespread practice nowadays in assessing the water and habitat quality, the use of hyporheic zone invertebrates is still in its infancy. In this study, classification and regression trees analysis were employed in order to assess the ecological requirements and the potential as bioindicators for the hyporheic zone invertebrates inhabiting four lowland chalk rivers (south England) with contrasting eutrophication levels (based on surface nitrate concentrations) and magnitude of land use (based on percentage of fine sediments load and median interstitial space). Samples of fauna, water and sediment were sampled twice, during low (summer) and high (winter) groundwater level, at depths of 20 and 35 cm. Certain groups of invertebrates (Glossosomatidae and Psychomyiidae caddisflies, and riffle beetles) proved to be good indicators of rural catchments, moderately eutrophic and with high fine sediment load. A diverse community dominated by microcrustaceans (copepods and ostracods) were found as good indicators of highly eutrophic urban streams, with moderate-high fine sediment load. However, the use of other taxonomic groups (e.g. chironomids, oligochaetes, nematodes, water mites and the amphipod Gammarus pulex), very widespread in the hyporheic zone of all sampled rivers, is of limited use because of their high tolerance to the analysed stressors. We recommend the use of certain taxonomic groups (comprising both meiofauna and macroinvertebrates) dwelling in the chalk hyporheic zone as indicators of eutrophication and colmation and, along with routine benthic sampling protocols, for a more comprehensive water and habitat quality assessment of chalk rivers. PMID:26531711

  10. Understanding heterogeneity in UK Chalk catchments and its influence on groundwater flooding

    Science.gov (United States)

    Peach, D. W.; Vounaki, T.; Jackson, C. R.; Hughes, A. G.; Wheater, H. S.

    2008-12-01

    The numerical simulation of groundwater flooding is increasingly necessary as this problem is gaining recognition from government and regulators and climate change may bring more extreme events. The Natural Environment Research Council of the UK is funding the British Geological Survey, Imperial College, and the Centre for Ecology and Hydrology to examine the problem of groundwater flooding in the Cretaceous Chalk of Berkshire, 50 kilometres west of London. Typically regional resource issues can be examined using traditional groundwater models that do not consider in detail the influence of flow in the unsaturated zone, but the delays in recharge transmission through this zone to the water table may be very significant in terms of flood timing and prediction. The position of ground elevation relative to water table is clearly important but not often considered in groundwater resource modelling. Groundwater level and stream (and flood) flow responses are important data that may be hard to gather from typical groundwater monitoring systems. These problems have been examined in a Chalk catchment in Berkshire where good records of the 2000-1 and 2003 flooding events have been collected, including flooded extent, rainfall, groundwater levels, river and spring flows. From this analysis, it appears that two groundwater mounds develop in the upper part of the Pang and Lambourn catchments. These mounds intersect dry valleys, which flowed for several months, the consequent flooding causing considerably disruption. Modelling of these events is providing new insight into the heterogeneity of Chalk transmissivity and storage parameters, enhanced knowledge of its dual permeability and porosity and demonstrating the importance of understanding the post-depositional hydrogeological history of the aquifer.

  11. Marine macrofossil communities in the uppermost Maastrichtian chalk of Stevns Klint, Denmark

    DEFF Research Database (Denmark)

    Hansen, Thomas; Surlyk, Finn

    2014-01-01

    -erosive bottom currents. It is draped by the upper Sigerslev Member, which was laid down in deeper water than any other chalk known from onshore Denmark. Deposition took place under quiet conditions, apparently not influenced by bottom currents. The sparse level-bottom community lived on a seafloor with low...... similarly mound-bedded lower Sigerslev Member. The number of polychaete species is also greater in the Højerup Member. The faunal differences reflect the shallower-water setting and a higher influx of food during deposition of the latter unit. The final Maastrichtian benthic macrofossil community at Stevns...

  12. Optimization of Spore Forming Bacteria Flooding for Enhanced Oil Recovery in North Sea Chalk Reservoir

    OpenAIRE

    Halim, Amalia Yunita; Nielsen, Sidsel Marie; Eliasson Lantz, Anna; Shapiro, Alexander

    2015-01-01

    Little has been done to study microbial enhanced oil recovery (MEOR) in chalk reservoirs. The present study focused on core flooding experiments to see microbial plugging and its effect on oil recovery. A pressure tapped core holder with pressure ports at 1.2 cm, 3.8 cm, and 6.3 cm from the inlet was used for this purpose. A spore forming bacterium, Bacillus licheniformis 421, was used as it was shown to be a good candidate in the previous study. Bacterial spore can penetrate deeper into the ...

  13. Prospects of Microbial Enhanced Oil Recovery  in Danish chalk rocks

    DEFF Research Database (Denmark)

    Rudyk, Svetlana Nikolayevna; Jørgensen, Leif Wagner; Bah Awasi, Ismail

      Microbial Enhanced Oil Recovery (MEOR) uses bacteria, producing gas (CO2), polymers or surfactants to help recover residual oil after the water injection depletes its possibilities. Two strains of Clostridia tyrobutiricum were investigated as possible candidates for MEOR  implementation in Danish...... chalk reservoir rocks. Parameters such as high salinity, low permeability, high temperature and toxic elements, being typical characteristics of Danish fields can cause limiting effects on MEOR applications. The work fulfilled showed that microbes can be adapted to higher salinities through a serial...

  14. Field burial results and SIMS analysis of the Chalk River glass blocks

    International Nuclear Information System (INIS)

    In 1959, 25 2-kg hemispherical blocks of aluminosilicate glass, each containing ∼90 MBq/g of mixed fission products, were buried in a sandy soil aquifer in the waste management area at the Chalk River Nuclear Laboratories. A second set of blocks, containing ∼260 MBq/g mixed fission products, was buried in 1960. One block from each test was retrieved in 1978 to undergo chemical and surface analysis. This report reviews the migration of the 90Sr and 137Cs plume in the soil and presents the results of SIMS depth profiling of the surface of a glass block. (author)

  15. CO2-foaming agent retention in fractured chalk models: Experiments and simulations

    OpenAIRE

    Kvæstad, Ann Helen

    2011-01-01

    Injection of CO2-gas can improve the oil recovery. In naturally fractured reservoirs such as chalk, injection of CO2-gas can result in early gas breakthrough because the gas can use the fractures as pathways from the injector to the producer. The pressure, temperature and oil properties in the reservoir can also lead to an unfavorable mobility for the gas. This can lead to low total sweep efficiency for the process. One method to increase the total sweep efficiency in the fractured reservoir ...

  16. Optimization of Spore Forming Bacteria Flooding for Enhanced Oil Recovery in North Sea Chalk Reservoir

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Nielsen, Sidsel Marie; Eliasson Lantz, Anna;

    2015-01-01

    was used for this purpose. A spore forming bacterium, Bacillus licheniformis 421, was used as it was shown to be a good candidate in the previous study. Bacterial spore can penetrate deeper into the chalk rock, squeezing through the pore throats. Our results show that B. licheniformis 421 when......-1.2 cm and 1.2-3.8 cm) during bacteria injection. Further seawater flooding after three days shut in period showed that permeability gradually increased in the first two sections of the core and started to decrease in the third section of the core (3.8-6.3 cm). Complete plugging was never observed in our...

  17. Burial diagenesis of deep sea chalk as reflected in Biot’s coefficient

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Alam, Mohammad Monzurul

    particles apparently is low and not correlated with porosity, probably because the pore-filling cementation in this interval causes Biot’s coefficient to decline as burial increases. Limestone from the water zone of the North sea Chalk Group follows the same stress trend as deep sea limestone. These results...... limestone as burial increases and porosity decreases. The porosity decrease is accompanied by an increasing velocity to elastic waves, and consequently a decreasing Biot’s coefficient, as estimated from velocity and density of core samples. When the effective burial stress is normalized to total horizontal...

  18. Burial diagenesis of deep sea chalk as reflected in Biot's coefficient

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Alam, Mohammad Monzurul

    particles apparently is low and not correlated with porosity, probably because the pore-filling cementation in this interval causes Biot's coefficient to decline as burial increases. Limestone from the water zone of the North sea Chalk Group follows the same stress trend as deep sea limestone. These results...... limestone as burial increases and porosity decreases. The porosity decrease is accompanied by an increasing velocity to elastic waves, and consequently a decreasing Biot's coefficient, as estimated from velocity and density of core samples. When the effective burial stress is normalized to total horizontal...

  19. Tracking selenium in the Chalk aquifer of northern France: Sr isotope constraints

    International Nuclear Information System (INIS)

    Highlights: • We report the chemistry of the Chalk groundwater affected by Se contamination. • Strontium isotopes were used to identify the groundwater bodies and their mixings. • The spatial and temporal Se variability is mainly linked to the presence of Se-rich clays. • Saturation or desaturation of Se-rich clays control Se mobility. - Abstract: Groundwater at the southern and eastern edges of France’s Paris Basin has a selenium content that at times exceeds the European Framework Directive’s drinking-water limit value of 10 μg/L. To better understand the dynamics of the Chalk groundwater being tapped to supply the city of Lille and the Se origins, we used a combination of geochemical and isotopic tools. Strontium isotopes, coupled with Ca/Sr, Mg/Sr and Se/Sr ratios, were used to identify the main groundwater bodies and their mixings, with the Mg/Sr and Se/Sr ratios constraining a ternary system. Groundwater in the agricultural aquifer-recharge zone represents a first end-member and displays the youngest water ages of the catchment along with the highest Sr isotopic signature (0.70842) and low Se contents. Anaerobic groundwater constitutes a second major end-member affected by water-rock interactions over a long residence time, with the lowest Sr isotopic signature (0.70789) and the lowest Se content, its low SF6 content confirming the contribution of old water. Se-rich groundwater containing up to 30 μg/L of Se represents a third major end-member, with an intermediate Sr isotopic ratio (0.70826), and is mainly constrained by the clayey Se-rich formation overlying the Chalk aquifer. The spatial and temporal Se variability in the groundwater is clearly linked to the presence of this formation identified as Tertiary and also to the hydrological conditions; saturation of the Se-rich clays by oxygenated groundwater enhances Se mobility and also Sr adsorption onto the clays. This multi-tool study including Sr isotopes successfully identified the Se

  20. Full-waveform Inversion of Crosshole GPR Data Collected in Strongly Heterogeneous Chalk: Challenges and Pitfalls

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Zibar, Majken Caroline Looms; Nielsen, Lars; Klotzsche, Anja; van der Kruk, Jan; Moreau, Julien; Stemmerik, Lars; Holliger, Klaus

    Chalk is an important reservoir rock for hydrocarbons and for groundwater resources for many major cities. Therefore, this rock type has been extensively investigated using both geological and geophysical methods. Many applications of crosshole GPR tomography rely on the ray approximation and...... address the importance of (i) adequate starting models, both in terms of the dielectric permittivity and the electrical conductivity, (ii) the estimation of the source wavelet, (iii) and the effects of data sampling density when imaging this rock type. Moreover, we discuss the resolution of the bedding...

  1. Field burial results and SIMS analysis of the Chalk River glass blocks

    International Nuclear Information System (INIS)

    In 1959, 25 2-kg hemispherical blocks of aluminosilicate glass, each containing ∼90 MBq/g of mixed fission products, were buried in a sandy soil aquifer in the waste management area at the Chalk River Nuclear Laboratories. A second set of blocks, containing ∼260 MBq/g mixed fission products, was buried in 1960. One block from each test was retrieved in 1978 to undergo chemical and surface analysis. This report reviews the migration of the /sup 90/Sr and /sup 137/Cs plume in the soil and presents the results of SIMS depth profiling of the surface of a glass block

  2. Waveform analysis of crosshole GPR data collected in heterogeneous chalk deposits

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Nielsen, Lars; Zibar, Majken Caroline Looms;

    2014-01-01

    be divided into two main units based on the traveltime analysis and interpretation of the cored material from the boreholes. The lower unit consists mainly of porous calcareous mudstone with occasional occurrences of flint nodules. The upper succession is c. 8 m thick and is fairly heterogeneous...... methods are highly dependent on the quality of the starting models (usually obtained from ray-based tomography), as well as on the assumptions made regarding the source signal. Adequate estimation of starting models and source waveform is, however, a challenging task for the strongly heterogeneous chalk...

  3. Environmental isotope studies related to groundwater flow and saline encroachment in the chalk aquifer of Lincolnshire, England

    International Nuclear Information System (INIS)

    The isotopes of tritium and carbon are used to study part of the North Lincolnshire Chalk aquifer in England. The tritium data support the view that the aquifer is a thin fissure system and indicate that some changes in flow direction have occurred owing to recent abstraction. The data are also consistent with other chemical data in elucidating groundwater entering the Chalk from deeper aquifers. Carbon isotopes are used to distinguish between saline water bodies and suggest that saline water was entrapped within the aquifer in the Eemian and Flandrian stages of the Pleistocene. (author)

  4. Deep saltwater in Chalk of North-West Europe: origin, interface characteristics and development over geological time

    DEFF Research Database (Denmark)

    Bonnesen, Ellen Prip; Larsen, F.; Sonnenborg, T.O.;

    2009-01-01

    location, saline water in the Chalk resides at depths from 40 to 80m and salinity increases with depth. Concentrations of chloride up to ca. 30,000ppm have been observed at depths of 400m. Measured vertical hydraulic heads in open boreholes suggest that advective groundwater flow is now restricted in...... deeper parts of the Chalk formation and diffusive transport is thus the predominant transport mechanism. Laboratory-measured porosity and effective diffusion coefficients were used as input to a numerical 1D diffusion model of the interface between freshwater in an upper, fractured aquifer and modified...

  5. The relation among porosity, permeability, and specific surface of chalk from the Gorm field, Danish North Sea

    DEFF Research Database (Denmark)

    Jeanette, Mortensen; Engstrøm, Finn; Lind, Ida

    1998-01-01

    The origin to the difference in the relationship between permeability and porosity for Danian and Maastrichtian chalk from the Gorm field offshore Denmark has been investigated. The investigation was based on 300 sets of core data (He-expansion porosity and air permeability) from the well Gorm N-22...... surface. Furthermore it was found that the nature of porosity (intrafossil, intergranular, etc.) had no significant influence on the air permeability, so that the permeability of the chalk can be calculated from total porosity and specific surface. Kozeny's empirical constant, c, was here determined...... analytically from a simple porosity model and Poiseuilles law....

  6. Proceedings of a workshop on geophysical and related geoscientific research at Chalk River, Ontario

    International Nuclear Information System (INIS)

    A large part of the Canadian Nuclear Fuel Waste Management Program is geoscience research and development aimed at obtaining information to quantify the transport of radionuclides through the geosphere and at determining the geotechnical properties required for disposal vault design. The geosphere at potential disposal sites is characterized in part by the use of remote sensing (geophysical) methods. In 1977 public concern about the disposal of radioactive waste resulted in field work being restricted to the site of Chalk River Nuclear Laboratories, which was used to develop, evaluate and compare various techniques in order to optimize the methods for obtaining geoscience information. Methods tested at Chalk River are to be applied at other research sites. Most investigations have been carried out around Maskinonge Lake, using about thirty boreholes sink into bedrock. The boreholes provide subsurface geological information that can be used as a reference to compare the responses of various geophysical methods and equipment. Regional studies, including airborne geophysical surveys, have also been conducted. The 25 papers presented at this workshop provide comprehensive documentation of the most significant results of geophysical studies. The workshop also provided an evaluation of geophysical techniques and their utility to the Nuclear Fuel Waste Management Program

  7. What are the governing processes during low-flows in a chalk catchment?

    Science.gov (United States)

    Lubega Musuuza, Jude; Coxon, Gemma; Hutton, Chris; Howden, Nicholas; Woods, Ross; Freer, Jim; Wagener, Thorsten

    2016-04-01

    Low flows are important because they lead to the prioritisation of different consumptive water usages, imposition of restrictions and bans, raising of water tariffs and higher production costs to industry. The partitioning of precipitation into evaporation, storage and runoff depends on the local variability in meteorological variables and site-specific characteristics e.g., topography, soils and vegetation. The response of chalk catchments to meteorological forcing especially precipitation is of particular interest because of the preferential flow through the weathered formation. This makes the observed stream discharge groundwater-dominated and hence, out of phase with precipitation. One relevant question is how sensitive the low flow characteristics of such a chalk catchment is to changes in climate and land use. It is thus important to understand all the factors that control low stream discharge periods. In this study we present the results from numerical sensitivity analysis experiments performed with a detailed physically-based model on the Kennet, a sub-catchment of the River Thames, in the UK during the historical drought years of the 1970's.

  8. Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea

    DEFF Research Database (Denmark)

    Røgen, Birte; Fabricius, Ida Lykke

    2002-01-01

    The permeability and capillary entry pressure of chalk reservoirs are controlled by their porosity and specific surface area. Measured permeabilities are in the range 0.025-5.3 mD and are successfully predicted by use of the Kozeny equation. In this paper we focus on the factors that control spec...

  9. Estimation of groundwater recharge to chalk and sandstone aquifers using simple soil models

    Science.gov (United States)

    Ragab, R.; Finch, J.; Harding, R.

    1997-03-01

    On the assumption that the water draining below the root zone is potentially available for groundwater recharge, two current UK methods for estimating annual groundwater recharge have been compared with a new soil model using data from four sites under permanent grass in the UK: two sites representative of the Chalk aquifer at Bridgest Farm (Hampshire) and Fleam Dyke (Cambridgeshire), and two sites on the Triassic sandstone at Bicton College (Devon) and Bacon Hall (Shropshire). A Four Root Layers Model (FRLM), the Penman-Grindley model and the UK Meteorological Office Rainfall and Evaporation Calculation System (MORECS) were used. The new soil model was run with potential evaporation as input both from the MORECS and from the Penman-Monteith equation. The models were run for the Chalk sites both with and without a bypass flow of 15% of rainfall. Bypass was not considered for the sandstone sites. The performance of the models was tested against neutron probes measurements of soil moisture deficits. In addition, the annual groundwater recharge estimated from the models was compared with the published values obtained from the 'zero flux plane' method. Generally, the Penman-Grindley model was more successful in predicting the time for soil to return to its field capacity than in predicting the magnitude of the soil moisture deficit. The annual groundwater recharge was predicted with reasonable accuracy. The MORECS relatively tended to overestimate the soil moisture deficits and to delay the time at which the soil returns to its field capacity. The consequences were underestimates of annual groundwater recharge, owing either to the higher values of potential evaporation calculated from the MORECS or tothe high available water capacity values associated with the soils under consideration. The new soil model (FRLM) predicts the soil moisture deficits successfully and hence is reliable in estimating the annual groundwater recharge. The model is capable of doing this with

  10. Magnetic field related mechanical tolerances for the proposed Chalk River superconducting heavy-ion cyclotron

    International Nuclear Information System (INIS)

    A four sector azimuthally varying field cyclotron with superconducting main coils has been proposed as a heavy-ion post-accelerator for the Chalk River MP Tandem van de Graaff. The radial profile of the average axial field will be variable using movable steel trim rods. The field errors due to coil, trim rod and flutter pole imperfections are calculated. Those considered are errors in the axial field, first and second azimuthal harmonic axial fields, transverse field and first azimuthal harmonic transverse field. Such fields induce phase slip, axial or radial coherent oscillations and can result in axial or radial beam instability. The allowed imperfections (tolerances) required to retain stability and maintain acceptably small coherent oscillation amplitudes are calculated. (author)

  11. Water temperatures within spawning beds in two chalk streams and implications for salmonid egg development

    Science.gov (United States)

    Acornley, R. M.

    1999-02-01

    Water temperatures within brown trout (Salmo trutta L.) spawning gravels were measured in two Hampshire chalk streams from October 1995 to April 1996 inclusive. During the winter, mean intra-gravel water temperatures were higher than those in the stream, and increased with depth in the gravel bed. The amplitude of diel fluctuations in water temperature decreased with depth in the gravel bed, although diel fluctuations were still evident at a depth of 30 cm. Differences in intra-gravel temperature gradients between the two study sites were attributed to differences in the amplitude of stream water temperature fluctuations and there was no evidence that either of the study sites were located in zones of upwelling groundwater. Published equations are used to predict, from temperature, the timing of important stages in the development of brown trout embryos (eyeing, hatching and emergence) for eggs spawned in the autumn and winter and buried at different depths in the gravel bed.

  12. Isotope and dissolved gas evidence for nitrogen attenuation in landfill leachate dispersing into a chalk aquifer

    International Nuclear Information System (INIS)

    The authors present data for the chemical, stable isotope (13C/12C, 15N/14N and 34S/32S), and dissolved gas (N2, Ar, O2 and CH4) composition of groundwaters sampled in and around a landfill site in Cambridgeshire, England. Decomposition of 3 x 106 m3 of largely domestic waste, placed in unlined quarries, has given rise to the formation of an NH4-rich leachate dispersing as a plume into the surrounding Middle Chalk aquifer. In addition to identifying zones of methanogenesis and SO4 reduction, the data indicate processes of NH4 transformation by either assimilation or oxidation, and losses by formation of N2. Depending on the mixing ratio between leachate and background water, it may be possible to account for all NH4 loss by combined nitrification + denitrification in a system where there are abrupt temporal and spatial changes in redox conditions

  13. Multi isotopic tools to understand selenium origins in groundwaters of the Chalk aquifer in Northern France

    Science.gov (United States)

    Cary, Lise; Gourcy, Laurence; Benabderraziq, Hind; Elkhattabi, Jamal; Laurent, Alexandra; Négrel, Philippe

    2013-04-01

    Four field wells exploiting the Chalk aquifer supply Lille city in water. The little catchment area is submitted to quantitative and qualitative pressure from industrial, urban and agriculture origins. Selenium (Se) concentrations are often higher than EU standards (0.12 µmol.L-1) for potable drinking water and can reach 0.4 μmol.L-1 leading to exploitation restrictions. An integrated study was settled to determine the water sources and dynamics of elements, with a focus on Se, with the goal of managing both water quality and quantity. After a large chemical characterisation of the system, a monthly sampling campaign was held in 2012 in four wells and in the close Deûle channel. In situ physical and chemical parameters, chemical analysis of major and trace elements with a special focus on redox-sensitive elements including SeIV, SeVI, FeII, stable water isotopes (δ18O, δ2H) and δ34S and δ18O of sulphates measures were undertaken. The chemical composition of solids sampled at various depths at vicinity of the four wells was analysed. Se concentrations in groundwaters and in the solid phase vary significantly. In the northern part of the Ansereuilles north of the Deûle channel, where the highest Se concentrations in solids was found in a 13 m alluvial clay deposit above the chalk, a first main type of waters can be defined with the variable and locally highest Se concentrations (0.19 to 0.4 µmol.L-1), relatively high and stable sulphate concentrations (2.5 µmol/L), no nitrates, dissolved Fe and Mn, negative δ34S (around -20 ‰) and δ18O typical of evaporated waters. A second main type of waters can be described at Houplin, south of the Deûle channel, where the geological profile show less than 1 mg/kg of Se, with intermediate Se concentrations (0.1 to 0.2 µmol/L), variable nitrate concentrations (0.4 to 1.2 mmol/L), not quantified dissolved Fe and Mn, sulphate concentrations close to 1.5 mmol/L, variable negative δ34S (-8 to -24 ‰) and δ18O in the

  14. Tracking selenium behaviour in chalk aquifer (northern France): Sr and 34S-sulphates isotopes constraints.

    Science.gov (United States)

    Cary, Lise; Benabderraziq, Hind; Elkhattabi, Jamal; Parmentier, Marc; Gourcy, Laurence; Négrel, Philippe

    2014-05-01

    Groundwaters in parts of the Paris Basin (France) are facing increasing selenium (Se) contents that can exceed the drinking water limit of 10 μg/L according to the European Framework Directive in the field of water policy (2000/60/EC). To better understand the groundwater origins and the selenium dynamics, the water chemistry of the Chalk aquifer supplying drinkable water to Lille city was studied. This area is submitted to quantitative and qualitative pressure from industrial, urban and agriculture origins. An integrated study was settled to determine the water sources and dynamics of elements, with a focus on Se. After a large chemical characterisation of the groundwater chemistry in the four field wells, a monthly monitoring was held in four wells and in the Deûle channel. Chemical analysis of major and trace elements, stable isotopes (δ18O, δ2H), strontium isotopes, and δ34S and δ18O of sulphates were realised. The chemical composition of solids sampled at various depths at vicinity of the four wells was also analysed. The specific geochemical signature of groundwater as revealed by Sr isotopes, in addition to element concentrations ratios like Mg/Sr and Se/Sr, highlighted mixture of three main groundwaters bodies: (1) the upstream groundwaters in the recharge area with the most radiogenic 87Sr/86Sr isotopic signature; (2) the confined groundwaters with high Sr concentrations due to water-rock interactions and the lowest 87Sr/86Sr isotopic signature close to the one of the chalk in Paris and London basins; (3) the Se-rich formations of Tertiary and Quaternary. The contents of Se, mainly present as SeV I (and locally as SeIV ), displayed spatial and temporal disparities that can be explained by geological and hydrogeological conditions. Se-rich clayed sediments originating from the dismantling of Se-rich tertiary formations (i.e. Ypresian) overlay the chalk formation and can be found in saturated conditions depending of the water table level. Oxidation of

  15. A description of the tritium facility at the Chalk River Laboratories

    International Nuclear Information System (INIS)

    AECL's Tritium Facility is located at its Chalk River Laboratories (CRL). The Tritium Facility was originally built to support the tritium technology needs for CANDU reactors and Canadian fusion program. The Tritium Facility commenced its operation in 1979. Since its inception, it has been involved in the development of heavy water detritiation and upgrading processes, development and testing of tritium-breeder materials and design and testing of fusion-fuel cleanup systems for fusion reactor applications, investigation of tritium-materials interactions, tritium storage getters etc. The Tritium Facility also contributed to the design, construction and commissioning activities of the Combined Electrolysis and Catalytic Exchange Upgrading and Detritiation (CECE-UD) Facility at CRL and the Wolsong Tritium Removal Facility (WTRF) in Korea. This paper describes the general set-up of the laboratory, its capabilities and the current tritium-related activities. (author)

  16. Sediment transport and siltation of brown trout (Salmo trutta L.) spawning gravels in chalk streams

    Science.gov (United States)

    Acornley, R. M.; Sear, D. A.

    1999-02-01

    Deposition rates of fine sediment into brown trout spawning gravels were measured at monthly intervals for a period of one year in a small channel of the River Test, Hampshire. Data were also collected on stream discharge, water depth, flow velocity and suspended sediment concentrations. Deposition rates followed a seasonal pattern and were maximal during periods of high discharge in the late winter/early spring when suspended sediment concentrations were high. The material deposited in the spawning gravels included silts and fine sands (<250 m) that were transported in suspension and coarser fragments of low density tufa-like material that were transported as bed load. The ecological implications of fine sediment deposition for salmonid egg survival in chalk streams are considered.

  17. Change in Biot's effective stress coefficient of chalk during pore collapse

    DEFF Research Database (Denmark)

    Alam, M. Monzurul; Fabricius, Ida Lykke

    2013-01-01

    grains could also change during elastic deformation of the grains in a rock mechanics test. Diagenetic change in grain contact cement of chalk can be compared with stress-induced change in the laboratory. The change in porosity is studied with reference to the change in effective stress on grain contacts...... porosity reduces at a slower rate. We noticed that presence of non carbonates and hydrocarbon could increase σ'm. During rock mechanics test in the lab, with increased applied stress, σ'm increases, Biot's effective stress coefficient shows a decreasing trend, while a minor porosity reduction was observed......Biot's effective stress coefficient (α) is a measure of how well grains in the rocks are connected with each other. The amount of contact cements between the grains determines the stiffness of rocks. Change in grain contact occurs during natural diagenesis of sedimentary rock. Contact between the...

  18. Water weakening of chalk explaied from a fluid-solid friction factor

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    to the macroscale failure and pore collapse properties. The Biot critical frequency incorporates the porosity, permeability, fluid density and fluid viscosity, where the latter is highly temperature dependent – it does not include the applied sound velocity frequency. The listed parameters are usually determined......The hypothesis behind this paper proposal is that the Biot critical frequency can be used to characterize the water weakening phenomenon physically. The Biot critical frequency determines the transition from where an applied sound velocity on a saturated porous chalk is dominated by viscous forces...... were tested at temperatures from 20°C to 130°C with the following pore fluids: fresh water, synthetic seawater of different chemical compositions, methanol, glycol, and oil of varying viscosity. The data was evaluated according to failure lines and yield envelopes for all fluids and temperatures while...

  19. Organically bound tritium (OBT) in soil at different depths around Chalk River Laboratories (CRL), Canada

    International Nuclear Information System (INIS)

    Atomic Energy of Canada Limited (AECL) Chalk River Laboratories (CRL) is a large nuclear research and test establishment with nuclear and non-nuclear facilities located in Chalk River, Ontario. The CRL Environmental Monitoring Program is designed to demonstrate that radiological exposure resulting from releases from the CRL site remain below the public dose limit specified in the regulations (1 mSv/year). This study was conducted to consolidate environmental effects following a continuous atmospheric tritium release observed at CRL. Soil samples were collected at depths of up to 20 cm using soil probes at the CRL site and surrounding areas. The samples were sectioned at 5 cm intervals, and HTO and OBT concentrations were measured in the samples. Prevailing winds at CRL are from NW and SE, which was suggested to be in close relationship with tritium distribution in environmental samples such as soils and plant leaves. The HTO concentration was the highest in surface soil water and plant leaves at a given sampling point. This result suggests that the concentration of tritium in surface soil water and in plants tissue free water essentially reflects the surrounding atmospheric tritium concentration. OBT concentrations in soil were measured at the historical HT release site, Plant Road, Mattawa Road and three background sites near CRL. The top layer of soil generally had the highest OBT concentration among collected soil samples. This result suggests that OBT concentrations are different from HTO concentrations at the same site and can be representative of previously released environmental tritium at the sampling point. The relationship between the OBT concentration in soil and the amount of tritium released into the environment will be useful for the evaluation of environmental tritium effects and the fate of tritium in the terrestrial ecosystem. The study points out that HTO shows shorter-term dynamic conditions, whereas OBT shows longer-term steady-state conditions

  20. Managing extremes in groundwater-dominated catchments: the Chalk of SE England (Invited)

    Science.gov (United States)

    Wheater, H. S.

    2009-12-01

    The Chalk aquifers of Southern and Eastern England are a dominant local and regional water resource, and rivers located on the Chalk outcrop have a characteristic behaviour and support valuable and protected aquatic ecosystems. In these catchments, typically less than 2% of rainfall is translated into stormflow response. Infiltration occurs into an unsaturated zone that varies in depth from zero at the stream to 100m at the interfluve. Seasonal groundwater recharge is translated into a seasonal river hydrograph, and the length of flowing river expands and contracts seasonally - so-called ‘bourne’ behaviour. Groundwater catchment areas also vary temporally, and stream-aquifer interactions can be complex. Extensive and long duration flooding in 2000/2001 highlighted the vulnerability of these systems to extremes of long duration rainfall (weeks and months). Source areas for runoff expand into dry valleys, springs break out in ‘new’ locations and given the normally low %runoff, highly non-linear flow response occurs. Conversely, droughts are also of major concern, particularly given scenarios of climate change for SE England. Water quality issues are also important, particularly nutrient pollution. These management concerns have focussed attention on the need for improved understanding, and for appropriate modelling tools for flood risk assessment and drought and water quality management. The paper addresses recent research into the historic behaviour of these systems under extremes, the relative roles of fracture and porous matrix flow in the unsaturated zone under extremes, and the nature of stream-aquifer interactions, including detailed experimental studies. Challenges for modelling are identified; for groundwater flooding conventional flood design approaches are inadequate, but groundwater models lack appropriate topographic constraints and the required spatial and temporal resolution; for drought, recharge estimation and diffuse pollution, better

  1. Environmental assessment of Chalk Point cooling tower drift and vapor emissions

    Energy Technology Data Exchange (ETDEWEB)

    Davis, E.A.

    1979-03-01

    An assessment is provided of selected environmental effects of operating the cooling towers and stacks of Units No. 3 and No. 4 of the Potomac Electric Power Company's generating station at Chalk Point, Maryland. The emphasis is on the magnitude of salt deposition to the area surrounding the cooling tower due to saline water drift. A secondary but important consideration is the magnitude of salt loading due to saline drift from the stack which uses saline river water in scrubbing flue gases. This salt loading together with that of the ambient salt background is assessed for its effects on soils, crops, native vegetation and man-made structures. Other atmospheric effects examined are: enhancement of ground level fogging and icing, enhancement of precipitation, and the flight hazards to aircraft. A numerical model of drift deposition has been developed and validated against the data collected in the Dyed Drift Experiment at Chalk Point. Use of the available data model predictions indicate that with fulltime, full load operation of both 600 MW(e) units significant levels of salt deposition occur only on the plant site within 0.4 km of the source. The predicted maximum salt deposition rates are given. The effects on soils, crops and native vegetation are predicted to be negligible at off-site locations. Significant effects to foliage of dogwood is predicted to occur at the most impacted on-site locations. Corrosion of structures at these locations could be enhanced under conditions of heavy plant operation. Enhancement of ground-level fogging, icing, and precipitation is expected to be negligible for all conditions of plant use. Hazards to aircraft because of restricted visibility, turbulence, and icing of structures and engines are estimated to be very slight and of no consequence.

  2. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea

    Directory of Open Access Journals (Sweden)

    Finn Surlyk

    2011-12-01

    Full Text Available The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab¬sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four dif¬ferent turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are rep¬resented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in

  3. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea: Plate 1

    Directory of Open Access Journals (Sweden)

    Surlyk, Finn

    2011-12-01

    Full Text Available The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab¬sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four dif¬ferent turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are rep¬resented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in

  4. The use of resistivity and gamma logging in lithostratigraphical studies of the chalk in Lincolnshire and South Humberside

    International Nuclear Information System (INIS)

    Electrical resistivity and natural gamma logs obtained from 70 boreholes in Lincolnshire and South Humberside can be interpreted in terms of lithology and show excellent agreement with the detailed lithostratigraphical divisions of the Chalk, obtained by Wood and Smith (1978) from the study of surface exposures. As, to the best of our knowledge, this sequence is complete, for the first time a direct correlation between continuous borehole logs and a detailed lithostratigraphical succession is possible. Important marl bands and some erosion surfaces and flint bands can be identified on the resistivity and gamma logs and traced over most of the study area. Stratigraphical positions of the logged boreholes can be determined and formation thicknesses measured. This information has enabled the construction of an accurate contour map of the elevation of the base of the Chalk and the eastward extension of the Caistor Monocline has been identified. (author)

  5. Changes in Specific Surface as observed by NMR, caused by saturation of Chalk with porewater bearing divalent Ions

    DEFF Research Database (Denmark)

    Katika, Konstantina; Addassi, Mouadh; Alam, Mohammad Monzurul;

    2014-01-01

    Nuclear Magnetic Resonance (NMR) spectrometry has proved to be a good technique for determining the petrophysical properties of reservoir rocks; such as porosity and pore size distribution. We investigated how pore water rich in divalent ions affect the NMR signal from chalk with two different...... depositional textures. We compared two cases. The first experiments on outcrop chalk with high salinity brines showed that saturation with divalent ions (Mg2+,Ca2+and SO42-) cause major shifts in the T2 distribution curve, probably due to precipitation in the pore space. In a second set of experiments, fluid......-to-volume ratio of the pore space. The results of this work could benefit the ongoing study on the optimization of the water composition for Enhanced Oil Recovery (EOR) methods and shed light on how it can affect the mechanical and physical properties of the rock....

  6. Using environmental tracers to assess the extent of river-groundwater interaction in a quarried area of the English Chalk

    Energy Technology Data Exchange (ETDEWEB)

    Darling, W.G., E-mail: wgd@bgs.ac.uk [British Geological Survey, Maclean Building, Wallingford OX10 8BB (United Kingdom); Gooddy, D.C. [British Geological Survey, Maclean Building, Wallingford OX10 8BB (United Kingdom); Riches, J. [Thames Water Utilities Limited, Rose Kiln Court, Rose Kiln Lane, Reading RG2 0BY (United Kingdom); Wallis, I. [British Geological Survey, Maclean Building, Wallingford OX10 8BB (United Kingdom)

    2010-07-15

    The Swanscombe area of Kent, SE England represents a typical example of a heavily quarried Chalk area currently undergoing re-development. Because the Chalk is also an important aquifer, a good understanding of groundwater movement is required if environmental impacts are to be minimised and the water resource maximised. In particular, the nature of the relationship between the River Darent and groundwater in the Swanscombe Chalk Block requires better characterisation. Here, 'environmental tracers' in the form of ambient concentrations of stable isotopes, chlorofluorocarbons (CFCs), sulphur hexafluoride (SF{sub 6}) and tritium ({sup 3}H) are used to investigate this and other aspects of groundwater movement in the vicinity of the quarries. Stable isotopic contrasts indicate little evidence for widespread river infiltration to the regional Chalk aquifer, although stable isotope and {sup 3}H data suggest that 20-35% of the abstraction by river-valley public water supply boreholes may be derived from the river. The CFCs, while present at above-modern concentrations in almost all groundwaters, can be used as tracers, indicating basically S-N flowpaths in the area south of the quarries, though sub-karstic conduits associated with areas of Palaeogene cover add a level of uncertainty at the local scale. Simple piston flow residence times based on SF{sub 6} range from 1 to 17 a, but the data are probably better interpreted in terms of mixing between varying amounts of modern recharge derived from the south and deeper stored groundwater. The information gained from environmental tracers can therefore contribute to effective resource management.

  7. PowerPoint or chalk and talk: Perceptions of medical students versus dental students in a medical college in India

    OpenAIRE

    Vikas Seth; Prerna Upadhyaya; Mushtaq Ahmad; et al, ...

    2010-01-01

    Vikas Seth, Prerna Upadhyaya, Mushtaq Ahmad, Vijay MogheDepartment of Pharmacology, Mahatma Gandhi Medical College, Jaipur, Rajasthan, IndiaPurpose: To assess students’ perceptions of the impact of PowerPoint (PPT) presentations in lectures in comparison to the traditional chalk and talk method and lectures using ­transparencies and overhead projector (TOHP). The study analyzes the preferences for teaching aids of medical students versus dental students.Methods: Second year ...

  8. Controls on the spatial and temporal variability of Rn-222 in riparian groundwater in a lowland Chalk catchment.

    OpenAIRE

    Mullinger, Neil J.; Pates, Jackie M.; Binley, Andrew M.; Crook, N. P.

    2009-01-01

    Radon is a powerful tracer of stream-aquifer interactions. However, it is important to consider the source and behaviour of radon in groundwater when interpreting observations of river radon in relation to groundwater discharge. Here we characterise the variability in groundwater radon concentrations in the riparian zone of a Chalk catchment. Groundwater 222Rn (radon) concentrations were determined in riparian zone boreholes at two sites in the Lambourn catchment, Berkshire, UK, over a two ye...

  9. Mass-transport deposits and reservoir quality of Upper Cretaceous Chalk within the German Central Graben, North Sea

    Science.gov (United States)

    Arfai, Jashar; Lutz, Rüdiger; Franke, Dieter; Gaedicke, Christoph; Kley, Jonas

    2016-04-01

    The architecture of intra-chalk deposits in the `Entenschnabel' area of the German North Sea is studied based on 3D seismic data. Adapted from seismic reflection characteristics, four types of mass-transport deposits (MTDs) are distinguished, i.e. slumps, slides, channels and frontal splay deposits. The development of these systems can be linked to inversion tectonics and halotectonic movements of Zechstein salt. Tectonic uplift is interpreted to have caused repeated tilting of the sea floor. This triggered large-scale slump deposition during Turonian-Santonian times. Slump deposits are characterised by chaotic reflection patterns interpreted to result from significant stratal distortion. The south-eastern study area is characterised by a large-scale frontal splay complex. This comprises a network of shallow channel systems arranged in a distributive pattern. Several slide complexes are observed near the Top Chalk in Maastrichtian and Danian sediments. These slides are commonly associated with large incisions into the sediments below. Best reservoir properties with high producible porosities are found in the reworked chalk strata, e.g. Danish North Sea, therefore MTDs detected in the study area are regarded as potential hydrocarbon reservoirs and considered as exploration targets.

  10. Edibility of sport fishes in the Ottawa River near Chalk River Laboratories

    International Nuclear Information System (INIS)

    To address the question of edibility of fish in the Ottawa River near Chalk River Laboratories (CRL), 123 game fish were collected for analysis from four locations: Mackey and Rolphton (45 km and 35 km upstream of Chalk River Laboratories (CRL), respectively), the Sandspit (Pointe au Bapteme) and Cotnam Island (1.6 km and 45 km downstream of CRL, respectively). Twenty-six to thirty-six game fish were collected at each location in 2007 and samples of flesh or bone were analyzed. Trap nets were used to collect only the fish required, allowing release of management-sensitive species. The focus was on walleye (Sander vitreus) because they are abundant and popular among anglers. A few northern pike (Esox lucius) and a smaller number of smallmouth bass (Micropterus dolomieui) were also collected at three of the four sites. Samples of the fish were analyzed for cesium-137 (137Cs), strontium-90 (90Sr), mercury (Hg), and selected organo-chlorine compounds. Concentrations of 137Cs in the flesh and 90Sr in the bones of sport fish were low and similar at all four locations and appear to reflect the global residuals from nuclear weapons testing (primarily in the 1960's) as opposed to releases from CRL. Possible explanations are: 1) Reductions in radionuclide releases from CRL in recent decades and 2) Relatively large foraging ranges of sport fish. Mercury concentrations were elevated in fishes in the Ottawa River and were significantly higher at the Sandspit and Rolphton than at Mackey and Cotnam Island (p<0.001). Mercury concentrations from the four sites are comparable to concentrations in other Ontario and Quebec lakes. It is advisable therefore, that consumers follow the fish consumption guidelines issued by provincial authorities when eating fish from the Ottawa River. Organo-chlorine compounds were not detected in walleye; however, they were detected in all eight of the pike collected at Cotnam Island. The highest organo-chlorine concentrations were measured in two of the

  11. Development of an Integrated Waste Plan for Chalk River Laboratories - 13376

    International Nuclear Information System (INIS)

    To further its Strategic Planning, the Atomic Energy of Canada Limited (AECL) required an effective approach to developing a fully integrated waste plan for its Chalk River Laboratories (CRL) site. Production of the first Integrated Waste Plan (IWP) for Chalk River was a substantial task involving representatives from each of the major internal stakeholders. Since then, a second revision has been produced and a third is underway. The IWP remains an Interim IWP until all gaps have been resolved and all pathways are at an acceptable level of detail. Full completion will involve a number of iterations, typically annually for up to six years. The end result of completing this process is a comprehensive document and supporting information that includes: - An Integrated Waste Plan document summarizing the entire waste management picture in one place; - Details of all the wastes required to be managed, including volume and timings by waste stream; - Detailed waste stream pathway maps for the whole life-cycle for each waste stream to be managed from pre-generation planning through to final disposition; and - Critical decision points, i.e. decisions that need to be made and timings by when they need to be made. A waste inventory has been constructed that serves as the master reference inventory of all waste that has been or is committed to be managed at CRL. In the past, only the waste that is in storage has been effectively captured, and future predictions of wastes requiring to be managed were not available in one place. The IWP has also provided a detailed baseline plan at the current level of refinement. Waste flow maps for all identified waste streams, for the full waste life cycle complete to disposition have been constructed. The maps identify areas requiring further development, and show the complexities and inter-relationships between waste streams. Knowledge of these inter-dependencies is necessary in order to perform effective options studies for enabling

  12. Edibility of sport fishes in the Ottawa River near Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.R.; Chaput, T.; Miller, A.; Wills, C.A., E-mail: leed@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2013-12-15

    To address the question of edibility of fish in the Ottawa River near Chalk River Laboratories (CRL), 123 game fish were collected for analysis from four locations: Mackey and Rolphton (45 km and 35 km upstream of Chalk River Laboratories (CRL), respectively), the Sandspit (Pointe au Bapteme) and Cotnam Island (1.6 km and 45 km downstream of CRL, respectively). Twenty-six to thirty-six game fish were collected at each location in 2007 and samples of flesh or bone were analyzed. Trap nets were used to collect only the fish required, allowing release of management-sensitive species. The focus was on walleye (Sander vitreus) because they are abundant and popular among anglers. A few northern pike (Esox lucius) and a smaller number of smallmouth bass (Micropterus dolomieui) were also collected at three of the four sites. Samples of the fish were analyzed for cesium-137 ({sup 137}Cs), strontium-90 ({sup 90}Sr), mercury (Hg), and selected organo-chlorine compounds. Concentrations of {sup 137}Cs in the flesh and {sup 90}Sr in the bones of sport fish were low and similar at all four locations and appear to reflect the global residuals from nuclear weapons testing (primarily in the 1960's) as opposed to releases from CRL. Possible explanations are: 1) Reductions in radionuclide releases from CRL in recent decades and 2) Relatively large foraging ranges of sport fish. Mercury concentrations were elevated in fishes in the Ottawa River and were significantly higher at the Sandspit and Rolphton than at Mackey and Cotnam Island (p<0.001). Mercury concentrations from the four sites are comparable to concentrations in other Ontario and Quebec lakes. It is advisable therefore, that consumers follow the fish consumption guidelines issued by provincial authorities when eating fish from the Ottawa River. Organo-chlorine compounds were not detected in walleye; however, they were detected in all eight of the pike collected at Cotnam Island. The highest organo

  13. Lithology, fracture intensity, and fracture filling of drill core from Chalk River research area, Ontario

    International Nuclear Information System (INIS)

    In 1977, 1978, and 1979, nine inclined cored boreholes, ranging in length from 113 to 704 m, were drilled in the Chalk River Research Area in order to define the geological subsurface characteristics of the rock mass at several selected test areas. A total of 2,458 metres of NQ-3 and HQ-3 core was obtained from the nine boreholes. Orthogneiss was the most predominant rock type intersected by the boreholes. Pyroxenite, amphibolite, metagabbro and dykes of diabase, pegmatite and aplite were also encountered. The crosscutting relationships and textures within the rocks indicate that the relative ages of the rock units, from youngest to oldest, are diabase; aplite and pegmatite dykes with no defined fabric; pyroxenite; meta-ferrogabbro; amphibolite; aplite and pegmatite dykes and pegmatite pods with a defined fabric; and orthogneiss. Textural characteristics and mineral assemblages indicate that the orthogneisses in the Chalk River Area are a product of regional, medium to high-grade metamorphism and belong to the upper amphibilite to granulite facies. A total of 35,597 fractures (an average of 14.5 fractures per metre) was observed in the core. Brecciated zones and open fractures were noted in the core from all of the boreholes, and major faults were identified in four of the nine boreholes. Nearly all of the fractures have a thickness between 0.4 and 1.2 mm and contain one or more types of filling. Chlorite and calcite are the most common types of filling. Epidote, hematite, clays, sulphides, talc, sericite, and rock fragments also occur in the fractures. The crosscutting relationships between fractures and the sequence of filling layers within the fractures indicate that several episodes of fracturing have occurred and that fractures containing more than one filling have probably been reactivated. A comparison of the geological logs from one of the boreholes with natural gamma, neutron-neutron and magnetic susceptibility logs indicates that certain rock types and

  14. Determination of transmissivity and dispersion in a confined chalk aquifer by simulation of field experiments with three tracers

    International Nuclear Information System (INIS)

    Storage and repumping of thermal energy in chalk aquifers during periods of surplus and deficit production respectively might be an economically feasible method to meet man's need for heating. To be able to evaluate the temporal and spatial variations of thermal energy transfer between water, which mainly flows in the chalk fissures, and the chalk matrix itself it is necessary to know the transmissivity and dispersion parameters of the aquifer. Based on this background, field tests with pumping of water and tracers have been carried out as shown. The fissured chalk aquifer of magnitude H = 16 m is confined by almost impervious top and bottom layers. Two wells with distance L = 101 m were established. A steady flow with Q1 Q2 = 10.9 m3/h was established within a period of 24 h. The radioactive tracers 3H and 82Br and the fluorescent tracer R-WT (rhodamine-water tracer) were injected at known concentrations within a period of 5 min. At time = 24 h valve V0 was opened and V2 closed and within the following 320 h a single well repumping (Q1 = -10.9 m3/h, Q2 = 0) and temporal detection of tracer concentrations were carried out until practically all concentrations were zero. The three concentration curves show a time to peak of about 12 h and a temporal distribution of the relative concentrations (peak concentration = 100% for all tracers) which is almost identical. The total repumped amount of tracer (with correction for radioactive decay) was 63%, 93% and 53% for 3H, 82Br and R-WT, respectively. The corresponding peak concentrations relative to injected concentrations were 1088, 1745 and 737 ppm. These data indicate a strong adsorption to the chalk matrix for R-WT and 3H but weak for 82Br. The simulation of measured concentration curves will be done by means of at least two models, M1-M2, which both include linear adsorption. With respect to permeability and dispersion M1 and M2 differ as follows: M1. Constant coefficients k and D for permeability and dispersion

  15. Inventory of radioactivity in Ottawa River-bed sediments near the Chalk River Laboratories

    International Nuclear Information System (INIS)

    AECL's Chalk River Laboratories (CRL) are situated on the Ontario side of the Ottawa River about 200 km NW of the City of Ottawa. Since 1947, water for cooling CRL's research reactors has been piped from and returned to the Ottawa River. From 1952 to the present time, cooling water has been discharged through the Process Sewer at a rate of 1.5 to 2 m3/s. The Outfall, which is the discharge from the Process Sewer, is in 18 m of water, 65 m offshore. Flow is directed toward the river surface through three 'diffuser vents,' creating a turbulent swirl at the surface and maintaining a patch of open water in winter. In addition to cooling water, the Outfall has, over the years, included small additional effluents from a heavy water recovery plant, a decontamination centre and a waste treatment centre. Although the effluent has been monitored and has met applicable regulatory requirements, investigations of the riverbed near the Outfall revealed radioactivity. In 2001, a riverbed reconnaissance and a detailed coring program were initiated for the purpose of determining the inventory of residual radioactivity. (author)

  16. Post-irradiation examination of the 37M fuel bundle at Chalk River Laboratories (AECL)

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Daniels, T. [Ontario Power Generation, Pickering, Ontario (Canada); Montin, J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2014-03-15

    The modified (-element (37M) fuel bundle was designed by Ontario Power Generation (OPG) to improve Critical Heat Flux (CHF) performance in ageing pressure tubes. A modification of the conventional 37-element fuel bundle design, the 37M fuel bundle allows more coolant flow through the interior sub-channels by way of a smaller central element. A demonstration irradiation (DI) of thirty-two fuel bundles was completed in 2011 at OPG's Darlington Nuclear Generating Station to confirm the suitability of the 37M fuel bundles for full core implementation. In support of the DI, fuel elements were examined in the Chalk River Laboratories Hot Cells. Inspection activities included: Bundle and element visual examination; Bundle and element dimensional measurements; Verification of bundle and element integrity; and Internal Gas Volume Measurements. The inspection results for 37M were comparable to that of conventional 37-element CANDU fuel. Fuel performance parameters of the 37M DI fuel bundle and fuel elements were within the range observed for similarly operated conventional 37-element CANDU fuel. Based on these Post Irradiation Examination (PIE) results, 37M fuel performed satisfactorily. (author)

  17. Stratigraphy and palaeoceanography of upper Masstrichtian chalks, southern Danish Central Graben

    Energy Technology Data Exchange (ETDEWEB)

    Ineson, J.R.; Buchardt, B.; Lassen, Susanne; Rasmussen, Jan A.; Schioeler, P.; Schovsbo, N.H.; Sheldon, E.; Surlyk, F. [Geological Survey of Denmark and Greenland, Copenhagen (Denmark)

    2006-07-01

    Upper Maastrichtian chalks form important hydrocarbon reservoirs in the Danish sector of the North Sea and have been intensively studied, yet their lithological uniformity can frustrate attempts to develop a high-resolution stratigraphic subdivision and a genetic understanding of the factors controlling production and sedimentation of the pelagic carbonate ooze. Recent research into these topics, by means of a multidisciplinary study involving quantitative/semiquantitative palynology, micropalaeontology (nannofossils, foraminifers) and isotope geochemistry, integrated with detailed sedimentology. Two key wells were selected, the M-1OX well from the Dan Field and the E-5X well from the Tyra SE Field, based on the extensive core coverage in these wells and on their position in the southern part of the Danish Central Graben where evidence of large-scale resedimentation (and consequent stratigraphic complexity) is uncommon within the Maastrichtian section. This study concentrated on a number of palaeoceanographic signals that can be derived from the sedimentary record. Planktonic organisms, both phytoplankton (e.g. coccolithophores, some dinoflagellates) and zooplankton (e.g. foraminifers) provide a record of conditions in the upper watermasses, largely within the photic zone, while bottom conditions are indicated by epifaunal/infaunal organisms (e.g. benthic foraminifers) and bioturbation, and by the sedimentological evidence of depositional processes at the sea floor. (LN)

  18. Water recharge and solute transport through the vadose zone of fractured chalk under desert conditions

    International Nuclear Information System (INIS)

    In the present study the inferred mechanism of groundwater recharge and contamination was studied using tracer concentrations in the fractured vadose zone of the Avdat chalk. The results of this study are important for an evaluation of groundwater contamination from existing and planned facilities in the northern Negev desert in Israel. This study focused on the vicinity of the Ramat Hovav industrial chemical complex in the northern Negev, which also includes the national site for hazardous waste. Water recharge and solute migration rates were examined in five core holes and one borehole which penetrate the entire vadose zone and enabled the collection of rock samples for chemical and isotopic analyses, and an observation of fracture distribution with depth. Tritium profiles were used to estimate water percolation rates through the vadose zone, chloride profiles were used to assess the migration rate of nonreactive solutes, and bromide profiles were also used to evaluate the migration rate of nonreactive contaminants. Deuterium and oxygen 18 profiles were used to assess the evaporation of the infiltrating water at and near land surface

  19. Canadian fusion breeder blanket program: Irradiation facilities at chalk river*1

    Science.gov (United States)

    Hastings, I. J.; Burton, D. G.; Celli, A.; Delaney, R. D.; Fehrenbach, P. J.; Howe, L. M.; Larson, L. L.; MacEwen, S. R.; Miller, J. M.; Naeem, T. A.; Sawicki, J. A.; Swanson, M. L.; Verrall, R. A.; Zee, R. H.

    1986-11-01

    The major irradiation facility at Chalk River Nuclear Laboratories (CRNL) is the NRU research reactor. Both unvented and vented capsule experiments on candidate blanket ceramics can be performed. In the unvented tests, tritium release data (HT-to-HTO ratio, tritium retention) are obtained by post-irradiation heating of the breeder ceramic in the presence of a sweep gas. Four tests have been completed on Li 2O and LiAlO 2. Effects of sweep gas composition, extraction vessel material and ceramic properties have been determined. Two unvented irradiations under the BEATRIX international breeder exchange program have been completed; analysis is underway. The vented tests involve long-term irradiation of candidate blanket materials. CRITIC-I, scheduled for mid-1986 under BEATRIX, will examine ANL-fabricated Li 2O in a six-month irradiation at 700-1200 K, varying sweep gas composition, with on-line HT/HTO measurement. Additionally, accelerator simulation techniques are available, using 70 kV and 2.0 MV mass separators, a 2.5 MV Van de Graaff accelerator and a tandem accelerator super-conducting cyclotron, the latter allowing irradiation with protons, deuterons or helium at 18-20 MeV.

  20. An overview of the waste characterization program at Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    In the last five years, Chalk River Nuclear Laboratories (CRNL) placed 17,000 m3 of wastes into storage (excluding contaminated soil and fill). Almost half of the waste was generated off-site. CRNL is now developing IRUS, an Intrusion Resistant Underground Structure, and the IST, an Improved Sand Trench, to replace storage with safe, permanent disposal. IRUS will be used to dispose of wastes with radiologically hazardous lifetimes between 150 and 500 years duration and the IST will be used for wastes with radiologically hazardous lifetimes of less than 150 years. A comprehensive Waste Characterization Program (WCP) is in place to support disposal projects. The WCP is responsible for (1) specifying the manifests for waste shipments; (2) developing and maintaining central databases for waste inventories and analytical data; and (3) developing the technologies and procedures to characterize the radiological and the physical/chemical properties of wastes. WCP work is being performed under the umbrella of a newly developed waste management quality assurance (QA) program. This paper gives an overview of the WCP with an emphasis on the requirements for determining radionuclide inventories in wastes, for implementing record-keeping systems and for maintaining a QA program for disposal operations

  1. Paleomagnetism of late Cretaceous and Eocene limestones and chalks from Haiti - tectonic interpretations

    Science.gov (United States)

    van Fossen, Mickey C.; Channell, James E. T.

    1988-06-01

    We have conducted a paleomagnetic study of limestones and chalks from Haiti which suggests that the island of Hispaniola is a composite of at least two tectonically independent blocks. Sampling sites are distributed among three widely separated localities, namely: Les Cayes (nine sites; 18.3°N. Latitude; 73.6°W. Longitude) and Beloc (five sites; 18.4°N. Latitude; 72.6°W. Longitude) which are located on the southern peninsula of Haiti, and a northern locality, Ennery (six sites; 19.5°N. Latitude; 72.5°W. Longitude). Stable magnetization components of dual polarity and moderately high blocking temperature were revealed through progressive thermal demagnetization of samples from all of the Beloc and Ennery sites, while seven of the nine Les Cayes sites possessed unstable magnetizations. Mean paleolatitudes calculated from Beloc and Ennery data show 8° of latitudinal separation that is of at least Eocene age. Pole positions (Beloc: 43.2°N. Latitude; 185.8°E. Longitude, α95=25.1° and Ennery: 66.1°N. Latitude; 31.3°E. Longitude, α95=19.7°) show both colatitudinal and angular discordance with the North American apparent polar wander path. Based on these disparities, we demonstrate that the implied tectonic displacements tend to support some aspects of previously published Caribbean plate tectonic models.

  2. The reduction of sample memory effects in the Chalk River AMS ion source

    International Nuclear Information System (INIS)

    The mechanism underlying Cl and I sample-to-sample interference in the new Chalk River AMS ion source has been studied and compared with the interference observed in an earlier ion source of different internal geometry. The distribution of sputtered material and its degree of migration was measured with the radioactive tracer, 82Br. The temperature dependence of the surface constituents was measured with the elastic recoil detection (ERD) technique and the effect of sample geometry and ion source cleaning was studied with elevated (5 x 10-10) 36Cl/Cl and 129I/I samples. These measurements indicate that a hot (> 350oC) aperture plate ahead of the sample can prevent the sputtering of contaminated regions near the sample. The plate itself remains relatively free of Cl or I itself since these elements or their Cs-gettered compounds are desorbed at this temperature. A small, fixed quantity of Cl or I on this surface is observed, which if sputtered by Cs+ ions, may contribute to ion source memory. Relative sample-to-sample interference for both Cl and I is about 10-3 after 20 min or l0-4 after 60 min. (author)

  3. Simulating Heterogeneous Infiltration and Contaminant leaching Processes at Chalk River, Ontario

    Science.gov (United States)

    Ali, M. A.; Ireson, A. M.; Keim, D.

    2015-12-01

    A study is conducted at a waste management area in Chalk River, Ontario to characterize flow and contaminant transport with the aim of contributing to improved hydrogeological risk assessment in the context of waste management. Field monitoring has been performed to gain insights into the unsaturated zone characteristics, moisture dynamics, and contaminant transport rates. The objective is to provide quantitative estimates of surface fluxes (quantification of infiltration and evaporation) and investigations of unsaturated zone processes controlling water infiltration and spatial variability in head distributions and flow rates. One particular issue is to examine the effectiveness of the clayey soil cap installed to prevent infiltration of water into the waste repository and the top sand soil cover above the clayey layer to divert the infiltrated water laterally. The spatial variability in the unsaturated zone properties and associated effects on water flow and contaminant transport observed at the site, have led to a concerted effort to develop improved model of flow and transport based on stochastic concepts. Results obtained through the unsaturated zone model investigations are combined with the hydrogeological and geochemical components and develop predictive tools to assess the long term fate of the contaminants at the waste management site.

  4. MAGS low level waste storage at Atomic Energy of Canada Limited's Chalk River Laboratories

    International Nuclear Information System (INIS)

    The recent introduction of Modular Above Ground Storage (MAGS) constitutes a substantial improvement in the way solid Low-Level Radioactive Waste (LLRW) is handled and stored at AECL's Chalk River Laboratories (CRL). The LLRW generally contains items such as lightly contaminated clothing, paper towels, glassware, used equipment and building materials produced at CRL, or received from Canadian hospitals, universities and other waste generators. These materials, previously stored in unlined sand trenches, are now being stored in a dry, monitored and more easily retrievable state in steel containers in MAGS storage buildings. The MAGS project involved design and construction of three elements: a Waste Handling Building, the first of a series of pre-engineered steel storage buildings, and a new Waste Management Area to house the storage buildings and containers of bulk waste. This project was well received by the local municipalities during the public consultation conducted as a part of the licensing process. The MAGS system entered service in 2002 and has operated satisfactorily since then. A second storage building was completed in 2003. (author)

  5. A critical assessment of simple recharge models: application to the UK Chalk

    Directory of Open Access Journals (Sweden)

    A. M. Ireson

    2012-10-01

    Full Text Available A framework for the rigorous quantification of the timing and magnitude of groundwater recharge is proposed. This involves developing a physically based model for the flow processes in the unsaturated and saturated zones that is consistent with the conceptualisation of the system, and with field observations. Subsequently, the essential behaviour of this model is emulated using a simpler model that can be applied within operational groundwater models. We take a UK Chalk aquifer as a case study. Flow processes are simulated convincingly using a dual permeability, equivalent continuum, Richards' equation model, applied to a 2-D hillslope transect along which four monitoring wells recorded water levels in the unconfined aquifer. A simple conventional recharge model that has been widely used was calibrated to reproduce the water table response simulated by the physically based model. The performance in reproducing the water table was surprisingly good, given the known discrepancies between the actual processes and the model representation. However, comparisons of recharge fluxes simulated by each model highlighted problems with the recharge processes in the simple model. Specifically, artificial bypass flow events during the summer were compensating for recharge that should have come from slow, continual drainage of the unsaturated zone. Such a model may still be useful for assessment of groundwater resources on a monthly basis, under non-extreme climatic conditions. However, under extreme wet or dry conditions, or under a changed climate the predictive capacity of such models is likely to be inadequate.

  6. Geologic feasibility of selected chalk-bearing sequences within the conterminous United States with regard to siting of radioactive-waste repositories

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, S.

    1975-11-01

    Various geologic and hydrologic parameters are evaluated in relation to assessing the potential for repository storage of high-level radioactive wastes within several stratigraphic sequences dominated by chalks and chalky limestones. The former lithology is defined as a carbonate rock consisting mainly of very fine-grained particles of micritic calcite. Although chalks also contain coarser-grained particles such as shells of fossil foraminifera and non-calcitic minerals like quartz, most contain more than 90 percent micritic material. The latter represents broken fossil coccolith plates. The chalk-dominated formations discussed are exposed and underlie two different physiographic provinces which nevertheless display a general similarity in both being regions of extensive plains. The Niobrara Formation occurs mainly within the Great Plains province, while the Austin Chalk of Texas and the Selma Group of Alabama and Mississippi are located in the western and eastern Gulf Coastal Plain, respectively. The preliminary assessment is that chalk-bearing sequences show some promise and are deserving of added consideration and evaluation. Containment for hundreds of thousands of years would seem possible given certain assumptions. The most promising units from the three studied are the Niobrara Formation and Selma Group. Regional and local conditions make the Austin more suspect.

  7. Groundwater monitoring and plume discharge zone characterization for the NRX radiostrontium plume at Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Olfert, J.M.; Audet, M.; Killey, D., E-mail: olfertjm@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2013-12-15

    Groundwater is the principal pathway for the migration of most radiological and non-radiological compounds from past and present operating areas at Atomic Energy of Canada Limited's Chalk River Laboratories (CRL). The CRL Groundwater Monitoring Program (GWMP) was established to measure the groundwater quality around the perimeters of areas affected, or potentially affected, by groundwater plumes. One of these is the NRX Rod Bays plume, a legacy plume that originated from the fuel storage bays of the National Research Experimental (NRX) reactor. This plume contains primarily {sup 90}Sr migrating along the groundwater flow system to the Ottawa River. A characterization study of the shoreline region was completed recently to map the plume discharge zone by collecting samples from mini-piezometers and groundwater seeps (springs) during a period of low river level. Analysis of discharging groundwaters determined that the {sup 90}Sr concentrations were very similar to those sampled from nearby (upgradient) GWMP monitoring wells. With this favorable correlation, the high density of seep and mini-piezometer sampling along the shoreline allowed refinements to be made in defining the northerly and southerly boundaries of the radiostrontium plume. The seep and mini-piezometer sampling also provided evidence that the monitoring wells sampled routinely within the CRL GWMP are positioned appropriately for providing representative sampling of the plume. Shoreline seep and mini-piezometer sampling can lead to refinements in the conceptual site model for plumes with limited effort and cost. The supplemental characterization work can also potentially identify other targets for routine groundwater monitoring. (author)

  8. Current status of the waste identification program at AECL's Chalk River Laboratories

    International Nuclear Information System (INIS)

    The management of routine operating waste by Waste Management and Decommissioning (WM and D) at Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories (CRL) is supported by the Waste Identification (WI) Program. The principal purpose of the WI Program is to minimize the cost and the effort associated with waste characterization and waste tracking, which are needed to optimize waste handling, storage and disposal. The major steps in the WI Program are: (1) identify and characterize the processes that generate the routine radioactive wastes accepted by WM and D - radioisotope production, radioisotope use, reactor operation, fuel fabrication, et cetera (2) identify and characterize the routine blocks of waste generated by each process or activity - the initial characterization is based on inference (process knowledge) (3) prepare customized, template data sheets for each routine waste block - templates contain information such as package type, waste material, waste type, solidifying agent, the average non-radiological contaminant inventory, the average radiological contaminant inventory, and the waste class (4) ensure generators 'use the right piece of paper with the right waste' when they transfer waste to WM and D - that is they use the correct template data sheets to transfer routine wastes, by: identifying and marking waste collection points in the generator's facility; ensuring that generators implement effective waste collection/segregation procedures; implementing standard procedures to transfer waste to WM and D; and, auditing waste collection and segregation within a generator's facility (5) determine any additional waste block characterization requirements (is anything needed beyond the original characterization by process knowledge?) This paper describes the WI Program, it provides an example of its implementation, and it summarizes the current status of its implementation for both CRL and non-CRL waste generators. (author)

  9. Magnetic susceptibility of rocks from boreholes CR-1 to CR-9 at Chalk River

    International Nuclear Information System (INIS)

    Magnetic susceptibility measurements made on rock cores obtained from boreholes at the Chalk River Research Area indicate that the foliated, granitic to granodioritic gneisses are weakly magnetic. Susceptibility values are about 5 x 10-4 S.I., two orders of magnitude less than average values for the Atikokan or Lac du Bonnet granites. Interpretation of the variations recorded in the gneisses in all cores is difficult because the average magnetic susceptibility level is near the limit of resolution of the measuring instrument used. However, in CR-6 and CR-9, mafic units intersect the boreholes and high magnetic susceptibility zones are seen. In CR-9 susceptibility values of the order of 5 x 10-2 S.I. characterize a dyke at depths of 40 to 60 m. A second high-susceptibility zone, distinctly different from the shallower one, is recorded at depths of 580 to 670 m with susceptibility of the orders of 5 x 10-3 S.I. This difference in susceptibility suggests mineralogical differences between the two units. The distinctive susceptibility signatures of these two units are better differentiated than signatures obtained from the other geophysical logs. In CR-6 only one high-susceptibility zone (of the order of 5 x 10-2 S.I.) is recorded in CR-6, at depths of 200 to 290 m. Its signature is similar in shape and intensity to the shallower unit observed in CR-9. Preliminary interpretation suggest continuity between these two zones. In CR-2 and CR-5, significant correlations exist among magnetic susceptibility, temperature anomalies and fracture occurrences. Contrary to observations at other research areas, fracture signatures in these two holes correspond to slight increases in susceptibility values. Alteration products associated with the fractures have higher susceptibility than the gneisses. Even though most of the recorded variations of the magnetic susceptibility are near the detection limit of the measuring instrument, significant features were observed and are discussed in

  10. Characterising the vertical variations in hydraulic conductivity within the Chalk aquifer

    Science.gov (United States)

    Williams, A.; Bloomfield, J.; Griffiths, K.; Butler, A.

    2006-10-01

    SummaryVarious field methods have been used to examine and quantify the vertical variations in aquifer properties within the Chalk aquifer at a LOCAR site in Berkshire, UK. The site contains three 100 m open boreholes and three sets of two nested piezometers within an area of about 100 m 2. There is also an 86 m deep abstraction borehole about 40 m from the site. The techniques that have been used at the site include: geophysical logging, borehole imaging, packer testing, dilution testing and pumping tests. The packer test results show that the permeability of the aquifer varies by three orders of magnitude over the 70 m of tested material with a strongly non-linear decrease with depth below ground level. Comparison with the borehole images show that some of the highly permeable zones appear to be associated with obvious fractures. However, large fractures can be seen in zones which have much lower permeability while some highly permeable zones appear to be associated with poorly developed fractures. Single borehole dilution tests have shown that there are differences in flow velocity depth profiles over a few tens of meters across the site. These are inferred to be because the different boreholes, although of similar drilled depth and very close proximity, intersect slightly different parts of the fracture network and hence the groundwater flow system. In particular, a flowing feature at the base of one borehole is not intersected by the second, which is drilled from a slightly higher elevation. A dilution test carried out whilst the aquifer was being pumped shows that different fractures become active when the aquifer is stressed. This has implications for the interpretation of flow logs performed under pumping.

  11. A compartment model for 90Sr contamination in a wetland at the Chalk River Laboratories

    International Nuclear Information System (INIS)

    Radioactive wastes originating from Canada's nuclear research and development program have been managed at the Atomic Energy of Canada Limited (AECL) Chalk River Laboratories (CRL) since 1946. In 1953 an area called Waste Management Area 'B' (WMA B) was developed to contain low and intermediate level solid waste (LLW and ILW respectively). Initially, all of the wastes were buried in unlined sand trenches or in asphalt lined trenches. These early trenches have been releasing strontium-90 (90Sr) to groundwater since 1954, resulting in an underground contaminant plume. A treatment system was constructed in 1994 and as a result the plume is being intercepted and treated for removal of 90SR. Prior to the establishment of the treatment system the plume extended south and discharged into a watercourse called 'Spring B', then into a wetland area called 'West Swamp'. Routine monitoring of Spring B and the West Swamp outflows for 90Sr has been conducted since the 1960s. A compartment model of the West Swamp was developed and validated against monitoring data for Spring B. The purpose of developing the model was to determine if a standard compartment model could describe 90Sr dynamics in a wetland to support environmental decision making. The model employed mass balance calculations to describe the movement/distribution of 90Sr between the primary system compartments: water/peat, sediment, vegetation and litter. This paper describes how the compartment model was developed and validated. The model can be used as a tool to evaluate remediation alternatives and to provide input to CRL site decommissioning plans. (author)

  12. Full-waveform inversion of cross-hole GPR data collected in a strongly heterogeneous chalk reservoir analogue with sharp permittivity and conductivity contrasts

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Zibar, Majken Caroline Looms; Moreau, Julien;

    2014-01-01

    Chalk sediments form an important reservoir for groundwater onshore and for hydrocarbons in the Danish sector of the North Sea. Cross-hole Ground-penetrating radar (GPR) tomography is an efficient method to investigate subtle porosity variations in the chalk. Traditional ray-based inversion...... techniques provide models that are overly smooth and have relatively low resolution. We present preliminary results from full-waveform inversion of data collected in strongly heterogeneous chalk. The resolution of the tomograms has improved significantly compared to models obtained from travel......-time tomography. The new models also reflect the variability seen in 1D drill core analysis. The results indicate that full-waveform inversion is a well-suited inversion technique for high-resolution time-lapse-based flow characterization. Read More: http://library.seg.org/doi/abs/10.1190/segam2014-1199.1...

  13. Hydrochemical trends, palaeorecharge and groundwater ages in the fissured Chalk aquifer of the London and Berkshire Basins, UK

    International Nuclear Information System (INIS)

    The hydrochemical, radiochemical, stable isotope, 14C and dissolved noble gas composition of groundwaters has been determined along two profiles across the confined, fissured Chalk aquifer of the London Basin of southern England, and for selected sites in the adjacent Berkshire Basin. During downgradient flow in the London Basin aquifer, the groundwater chemistry is modified by water-rock interactions: congruent and incongruent reaction of the carbonate lithology resulting in enhanced Mg/Ca and Sr/Ca ratios and 13C contents with increased residence times; redox and ion exchange reactions; and towards the centre of the Basin, mixing with a residual saline connate water stored in the Chalk matrix. There is evidence from anomalous water chemistries for a component of vertical leakage from overlying Tertiary beds into the confined aquifer as a result of historical dewatering of the aquifer. Dissolved noble gas contents indicate the climate was up to 4.5C cooler than at present during recharge of the waters now found in the centres of both Basins; stable isotope (2H and 18O) depletions correspond to this recharge temperature change. For evolved waters having δ13 -8per thousand PDB a negative linear correlation is demonstrated between derived recharge temperatures and δ13C values, which is interpreted as mixing between relatively warm, light isotopic, fracture-borne waters and cooler stored waters of the matrix having a 13C signature more or less equilibrated with the Chalk. From geochemical (14C, 4He) age estimates, the abstracted water is interpreted as being either of wholly Holocene/post-Devensian glacial origin, or an admixture of Holocene and Late Pleistocene pre-glacial (cold stage interstadial) recharge. Devensian pleniglacial stage waters of the Last Glacial Maximum are not represented. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Mechanical and chemical processes affecting the chalk during burial, insights from combined reflection seismics, well data and field work

    DEFF Research Database (Denmark)

    Moreau, Julien; Boussaha, Myriam; Thibault, Nicolas Rudolph;

    2014-01-01

    works have been performed with astronomical calibration based on stable isotope stratigraphy, wireline logs as well as several palaeontological proxies and detailed sedimentological analysis. Since a couple of decades, a specific kind of fractures has been described in the Chalk of Denmark, the so...... along the fractures (the compaction bands). The link between these different features has been realised thanks to the simultaneous analyses of large-scale geophysical data and small-scale core and field geological observations, providing a better understanding of the complex processes of lithification...

  15. Management of legacy spent nuclear fuel wastes at the Chalk River Laboratories: the challenges and innovative solutions implemented

    International Nuclear Information System (INIS)

    AECL has operated research reactors at the Chalk River Laboratories (CRL) site since 1947, for the purpose of nuclear energy and scientific research and for the production of radioisotopes. During the 1950s and 60s, a variety of spent nuclear fuel wastes were produced by irradiating metallic uranium and other prototype fuels. These legacy waste fuels were initially stored in water-filled fuel storage bays for a period of several years before being placed in storage containers and transferred to the CRL Waste Management Areas (WMAs), where they have been stored in below-grade, vertical cylindrical steel and concrete structures called 'tile holes'. (author)

  16. Canada, Atomic Energy of Canada Limited (AECL), Chalk River Labs: Reuse and Licence Termination of a Number of Facilities at the Chalk River Labs to Allow for Refurbishment of the Site. Annex A. I-1

    International Nuclear Information System (INIS)

    Chalk River Labs is located along the Ottawa River in Ontario, Canada, approximately 200 km north-west of Ottawa. The site began construction in 1944 following the expropriation of approximately 1 500 ha of land. A number of research reactors were constructed at the site along with numerous nuclear labs, hot cells and administrative facilities in support of the research and development work planned for the site. The principal occupants of the Chalk River site are AECL employees with a strong presence from National Resources Canada (NRC) and other small research groups. The site is undergoing substantial changes with an emphasis on minimizing the impact of increasing the builtup area footprint in conjunction with site upgrades and new build projects. To accomplish this task, a number of refurbishment and decommissioning projects were planned. Decommissioning projects were initiated to make room for new development through a number of initiatives. The decommissioning mandate includes the removal of a select group of original deteriorating facilities to make room for new construction and to decommission other facilities to facilitate redevelopment and reuse of the available space. In Canada, the Canadian Nuclear Safety Commission (CNSC) issues nuclear licences. The licensees must demonstrate that it is safe to continue operations of the nuclear site and request a renewal of their licence. CNSC will issue a new operating licence for a specific period of time at which the licensee must demonstrate that it is safe to proceed with a licence renewal. A request to terminate a licensable activity must be submitted to the CNSC. Upon approval to proceed, it must be demonstrated that the licensable activities have ceased and the facility has been appropriately decommissioned. Licence termination requires a demonstration that the land or previous activities presents a low risk and that the process can be used to support redevelopment because it results in a scrutinized

  17. Monitoring debris flow induced channel morphodynamics with terrestrial laser scanning, Chalk Cliffs, CO (Invited)

    Science.gov (United States)

    Wasklewicz, T. A.; Staley, D. M.

    2010-12-01

    Debris flows are important geomorphic agents in alpine drainages. They have been linked with channel initiation in headwater streams, connectivity of organic material and sediment through drainage basins, and as hazards to human development in and adjacent to steep watersheds. Debris flows also significantly alter channel morphometry at a variety of spatial scales. Of particular interest are topographic changes associated with multiple surge fronts within a debris flow as well as between several debris flows. An unnamed tributary stream to Chalk Creek, CO has over the last decade experienced one to four debris flow events annually. Four field sampling campaigns were conducted in the summer and fall of 2009. A Leica ScanStation 2, in conjunction with a robust local control network, were used to capture channel morphodynamics along five stream reaches prior to the debris flow season and after three debris flows. Point cloud data from the scanner permit the generation of two centimeter planimetric resolution digital terrain models (DTM). DTM-of-difference analyses and measures of slope, roughness, sediment transport volumes and channel dimensions were employed to detect spatial and temporal morphometric changes. The first debris flow occurred on unsaturated bed material and resulted in aggradation along 3 of the 5 reaches. One reach, a bedrock step, remained relatively unchanged, while the final reach saw significant erosion along boulder steps in the channel and an associated mass failure adjacent to the stream bank through this section. The second debris flow resulted in net aggradation along all of the reaches. The third and largest debris flow took place on saturated bed materials. The flow produced net erosion along all reaches. Significant channel changes were associated with the headward erosion of debris flow snouts and bank failures associated with undercutting of angle-of-repose slopes during debris flow erosion. Analysis of the potential relationships

  18. Spatial analysis of Carbon-14 dynamics in a wetland ecosystem (Duke Swamp, Chalk River Laboratories, Canada)

    International Nuclear Information System (INIS)

    A detailed survey was conducted to quantify the spatial distribution of 14C in Sphagnum moss and underlying soil collected in Duke Swamp. This wetland environment receives 14C via groundwater pathways from a historic radioactive Waste Management Area (WMA) on Atomic Energy Canada Limited (AECL)'s Chalk River Laboratories (CRL) site. Trends in 14C specific activities were evaluated with distance from the sampling location with the maximum 14C specific activity (DSS-35), which was situated adjacent to the WMA and close to an area of groundwater discharge. Based on a spatial evaluation of the data, an east-to-west 14C gradient was found, due to the influence of the WMA on 14C specific activities in the swamp. In addition, it was possible to identify two groups of sites, each showing significant exponential declines with distance from the groundwater source area. One of the groups showed relatively more elevated 14C specific activities at a given distance from source, likely due to their proximity to the WMA, the location of the sub-surface plume originating from the WMA, the presence of marsh and swamp habitat types, which facilitated 14C transport to the atmosphere, and possibly, 14C air dispersion patterns along the eastern edge of the swamp. The other group, which had lower 14C specific activities at a given distance from the groundwater source area, included locations that were more distant from the WMA and the sub-surface plume, and contained fen habitat, which is known to act as barrier to groundwater flow. The findings suggest that proximity to source, groundwater flow patterns and habitat physical characteristics can play an important role in the dynamics of 14C being carried by discharging groundwater into terrestrial and wetland environments. - Highlights: • Groundwater represents an important source of volatile radionuclides to wetlands. • Habitat type influenced 14C transport from sub-surface to surface environments. • C-14 specific activity

  19. Radon levels in dwellings in chalk terrain. Development and analysis of distributional and causal models

    International Nuclear Information System (INIS)

    This thesis investigates the range, distribution and causes of high radon levels in dwellings in the Brighton area of Southeast England. Indoor radon levels were measured in more than 1000 homes. The results show that high radon levels can arise in an area previously considered to offer low radon potential from local geological sources. Climate and building-related factors were found to affect significantly the radon levels in dwellings. Multiple regression was used to determine the influence of the various factors on indoor radon levels and an empirical model develop to predict indoor radon levels. The radon hazard, independent of building-related effects, was determined for each surveyed location by adjusting the radon measurement to that expected on the ground floor of a 'model' dwelling. This standardised set of radon levels was entered into a geographical information system (GIS) and related to surface geology. The geometric mean radon level for each lithological unit was plotted to produce a radon hazard map for the area. The highest radon levels were found to be associated with the youngest Chalk Formations, particularly where they meet overlying Tertiary deposits, and with Clay-with-Flints Quaternary deposits in the area. The results were also converted to the radon activity equivalent to that expected from the NRPB's standard dual-detector dwelling survey method and analysed by lognormal modelling to estimate the proportion of dwellings likely to exceed the UK Action Level of 200 Bq/m3 for each lithological unit. The likely percentages of dwellings affected by radon thus obtained were mapped to lithological boundaries to produce a radon potential map. The radon hazard map and the empirical radon model facilitate the prediction of radon levels in dwellings of comparable construction and above similar geology and should further the understanding of the behaviour of radon gas in buildings to allow indoor radon concentrations to be controlled. The radon

  20. Laboratory and field measurements of the self-potential (SP) in chalk, with application to monitoring of saline intrusion

    Science.gov (United States)

    MacAllister, D.; Jackson, M.; Butler, A. P.; Vinogradov, J.

    2013-12-01

    Saline intrusion is a global phenomenon, affecting the availability of freshwater in coastal aquifers. The aim of this work is to investigate whether measurements of self-potential (SP) can be used to monitor the intrusion of seawater into coastal aquifers, with specific application to the UK chalk aquifer in the vicinity of Brighton on the south coast of the UK. The SP arises to maintain electrical neutrality when a separation of charge occurs due to gradients in pressure (electrokinetic (EK) or streaming potential) and concentration (electrochemical (EC) potential). Concentration gradients are a characteristic feature of saline intrusion and may give rise to a measureable EC potential. In addition, an EK potential will arise during abstraction. Laboratory and field SP measurements are used to investigate the magnitude of the EK and EC potentials in the UK chalk aquifer during saline intrusion. Laboratory measurements yield an EK coupling coefficient, relating the gradient in voltage to the gradient in pressure when the total current is zero, of -60 mV/MPa in samples saturated with groundwater, and -1 mV/MPa in samples saturated with seawater. This result agrees with earlier work suggesting the EK potential is suppressed at high salinity due to a compressed electrical double layer. The EC coupling is dominated by diffusion potentials arising from the concentration gradient across the saline front. Field experiments suggest that the EK component of the SP in the chalk is very small under ambient conditions, even in freshwater zones, because gradients in hydraulic head are small owing to the high conductivity of the pervasive fracture networks. However, a pumping test conducted in the chalk aquifer at a field site in Berkshire induced a measureable EK response with a coupling coefficient of magnitude consistent with the freshwater EK coupling coefficient obtained in the laboratory. SP monitoring at an observation borehole near Brighton reveals semi-diurnal SP

  1. Validity of chalk and bentonite application in soil and water on reducing the absorption of ratio-strontium and radio-cerium by crop

    International Nuclear Information System (INIS)

    Effects of the chalk and bentonite application in soil and surface water respectively on reducing the absorption of 89Sr and 141Ce by crop (especially in the edible part of crop) were studied by using isotope tracer techniques. The results showed that the specific activity of 89Sr in the ryegrass and Chinese cabbage could be decreased significantly by chalk application in the soil. The reduced ratio of 89Sr absorption of Chinese cabbage and ryegrass reached 77.7% and 35.2% respectively with the chalk application of 20 g/kg soil. The specific activity of 89Sr in ryegrass and Chinese cabbage followed obvious negative linear correlation with the quantity of application chalk in the soil. The specific activity of 141Ce in surface water, chaff and brown rice decreased by application bentonite in the surface water, which led to the lower accumulation of 141Ce in paddy. However, the absorption and accumulation of 141Ce in root and straw could not be changed. The specific activity of 141Ce in soil followed a negative exponential relation with depth of soil profile

  2. The role of diagenisis in the hydrogeological stratification of carbonate aquifers: an example from the chalk at Fair Cross, Berkshire, UK

    Directory of Open Access Journals (Sweden)

    J. Bloomfield

    1997-01-01

    Full Text Available Carbonate rocks form important aquifers in many parts of the world and in north-west Europe the Chalk is a primary source of potable water. When flushed with relatively fresh groundwaters, the Chalk may undergo significant diagenetic alteration at relatively shallow depths resulting in a physically and hydrogeochemically stratified aquifer. Diagenetic affects may have important implications for the effective exploitable thickness of the Chalk aquifer and for water quality. In order to assess the affects of diagenesis on the properties of carbonate aquifers, matrix porosity, permeability, pore water and rock chemistry profiles have been analysed for a 300 m deep borehole through the Chalk at the western end of the London Basin. An abrupt change in the matrix porosity profile at 155 mbgl indicates a change in dominant mode of historic diagenesis from mechanical compaction above 155 mbgl to predominantly pressure solution compaction below 155 mbgl. Pore water and rock chemistry profiles also change abruptly across this depth interval, suggesting that the present day hydrogeology is controlled by historic diagenetic trends. Below 155 mbgl, pore waters are relatively saline and there is no evidence for groundwater flow; above 155 mbgl pore waters are relatively fresh and geochemical evidence for incon-gruent carbonate dissolution indicates contemporary groundwater circulation. Possible physical and chemical evolution paths for the Chalk at Fair Cross are discussed. The results provide a hydrogeological context for other studies of the long-term response of carbonate aquifers to base-line changes in sea-level and pore water chemistry and also enable studies with relatively short time-frames or of localized phenomena to be placed in the broader context of the evolution of carbonate aquifers.

  3. Simulations of Two-Well Tracer Tests in Stratified Aquifers at the Chalk River and the Mobile Sites

    Science.gov (United States)

    Huyakorn, Peter S.; Andersen, Peter F.; Molz, Fred J.; Güven, Oktay; Melville, Joel G.

    1986-07-01

    A simulation study of two-well injection-withdrawal tracer tests in stratified granular aquifers at two widely separated sites is presented. The first site is located near the Chalk River Nuclear Laboratories in Canada, and the second site is located in Mobile, Alabama. Field data and test conditions at these sites are substantially different in terms of vertical distributions of hydraulic conductivity, well spacings, flow rates, test durations, and tracer travel distances. Furthermore, the test at the Chalk River site was conducted in a recirculating mode, whereas the test at the Mobile site was conducted in a nonrecirculating mode. Simulations of these tests were performed in three dimensions using the curvilinear finite element model developed in the previous paper of this series. The simulations incorporated measured vertical variations in relative hydraulic conductivity and local dispersivity values that are small fractions (between 1/1000 and 1/100) of the spacing between the injection and the withdrawal wells. The local dispersivities are used to account for local hydrodynamic dispersion and are chosen independently so that they are not affected by the scales of the tests. Simulation results obtained from the model are presented. Interpretation of these results is made in conjunction with measured breakthrough curves at the withdrawal well and multilevel observation wells. For the Chalk River site, predicted and measured breakthrough curves at the withdrawal well are in good agreement over the earlier part of the test duration. Deviation of the field data from the model prediction occurs over the second part, where the predicted breakthrough curves show a declining trend but the field data plot does not. For the Mobile site, predicted and measured breakthrough curves at the withdrawal well show similar trends throughout the entire test duration and are in good agreement overall. Model predictions of the effect of hydraulic conductivity stratification on

  4. Analysis and applications of microorganisms from a chalk oil reservoir in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Kaster, Krista Michelle

    2009-03-15

    Ekofisk a chalk oil reservoir in the Norwegian sector of the North Sea was found to harbour an active and diverse microbial community. Microbial actives may be deleterious in nature as in reservoir souring or maybe advantageous as in microbial enhanced oil recovery. The aim of this study was to characterise the microbial communities in the Ekofisk oil reservoir and to gain insight into the microbial mechanisms important for the a) control of reservoir souring, and b) which can be utilized in enhanced oil recovery. Produced water samples from the Ekofisk oil reservoir were analysed using both culture-dependent and -independent techniques. The Ekofisk microbial community was found to be dominated by thermophilic microorganisms many of which were capable of either sulphidogenic or methanogenic physiologies. They were similar to organisms that have been previously identified from oil reservoir fluids. The dominant organisms identified directly from the produced water samples had sequences similar to members of the genera Thermotoga, Caminicella, Thermoanaerobacter, Archaeoglobus, Thermococcus, and Methanobulbus. Enrichment cultures obtained from the produced water samples were dominated by sheathed rods. Sequence analyses of the cultures indicated predominance of the genera Petrotoga, Arcobacter, Archaeoglobus and Thermococcus. Reservoir souring caused by sulphide production due the activity of sulphate reducing prokaryotes (SRP) may be reduced by the injection of nitrate or nitrite. Nitrate or nitrite mitigates sulphide production either by the stimulation of nitrate reducing bacteria (NRB) through nitrate addition or via metabolic inhibition of the reduction of sulphite to sulphide by nitrite. Here we found that nitrate addition was ineffective at controlling souring whereas nitrite proved very effective at inhibiting sulphate reduction even at very low concentrations (0.25 mM - 1 mM) in both batch culture and bioreactor studies. To investigate microbial utilization

  5. High frequency seismic monitoring of debris flows at Chalk Cliffs (CO), USA

    Science.gov (United States)

    Coviello, Velio; Kean, Jason; Smith, Joel; Coe, Jeffrey; Arattano, Massimo; McCoy, Scott

    2015-04-01

    A growing number of studies adopt passive seismic monitoring techniques to investigate slope instabilities and landslide processes. These techniques are attractive and convenient because large areas can be monitored from a safe distance. This is particularly true when the phenomena under investigation are rapid and infrequent mass movements like debris flows. Different types of devices are used to monitor debris flow processes, but among them ground vibration detectors (GVDs) present several, specific advantages that encourage their use. These advantages include: (i) the possibility to be installed outside the channel bed, (ii) the high adaptability to different and harsh field conditions, and (iii) the capability to detect the debris flow front arrival tens of seconds earlier than contact and stage sensors. Ground vibration data can provide relevant information on the dynamics of debris flows such as timing and velocity of the main surges. However, the processing of the raw seismic signal is usually needed, both to obtain a more effective representation of waveforms and to decrease the amount of data that need to be recorded and analyzed. With this objective, the methods of Amplitude and Impulses are commonly adopted to transform the raw signal to a 1-Hz signal that allows for a more useful representation of the phenomenon. In that way, peaks and other features become more visible and comparable with data obtained from other monitoring devices. In this work, we present the first debris flows seismic recordings gathered in the Chalk Cliffs instrumented basin, central Colorado, USA. In May 2014, two 4.5-Hz, three-axial geophones were installed in the upper part of the catchment. Seismic data are sampled at 333 Hz and then recorded by a standalone recording unit. One geophone is directly installed on bedrock, the other one mounted on a 1-m boulder partially buried in colluvium. This latter sensor integrates a heavily instrumented cross-section consisting of a 225 cm2

  6. Assessing inventories of past radioactive waste arisings at Chalk River Laboratories

    International Nuclear Information System (INIS)

    Internationally, a great deal of progress has been made in improving the management of currently accumulating and anticipated future radioactive wastes. Progress includes improved waste collection, segregation, characterization and documentation in support of disposal facility licensing and operation. These improvements are not often very helpful for assessing the hazards of wastes collected prior to their implementation, since, internationally, historic radioactive wastes were not managed and documented according to today's methods. This paper provides an overview of Atomic Energy of Canada Limited's (AECL) unique approach to managing its currently accumulating, low-level radioactive wastes at Chalk River Laboratories (CRL) and it describes the novel method AECL-CRL has developed to assess its historic radioactive wastes. Instead of estimating the characteristics of current radioactive wastes on a package-by-package basis, process knowledge is used to infer the average characteristics of most wastes. This approach defers, and potentially avoids, the use of expensive analytical technologies to characterize wastes until a reasonable certainty is gained about their ultimate disposition (Canada does not yet have a licensed radioactive waste disposal facility). Once the ultimate disposition is decided, performance assessments determine if inference characterization is adequate or if additional characterization is required. This process should result in significant cost savings to AECL since expensive, resource-intensive, up-front characterization may not be required for low-impact wastes. In addition, as technological improvements take place, the unit cost of characterization usually declines, making it less expensive to perform any additional characterization for current radioactive wastes. The WIP-III data management system is used at CRL to 'warehouse' the average characteristics of current radioactive wastes. This paper describes how this 'warehouse of information

  7. Investigation of CO2 Enhanced Oil Recovery Using Dimensionless Groups in Wettability Modified Chalk and Sandstone Rocks

    Directory of Open Access Journals (Sweden)

    Vahid Alipour Tabrizy

    2014-01-01

    Full Text Available The paper addresses enhanced oil recovery in chalk and sandstone rocks by CO2 injection, with different wettability, porosity, and permeability as well as injection rate and flooding conditions. Results indicate that an increase in Bond number has a positive effect on oil recovery whereas for capillary number, there is a limit in which recovery is improving. This limit is estimated when the pressure drop by viscous force is approximately equal to the threshold balance between capillary and gravity forces. A dimensionless group is proposed that combines the effect of capillarity, injection rate, permeability, and CO2 diffusion on the oil recovery. Recovery from all experiments in this study and reported data in the literature shows a satisfactory relationship with the proposed group.

  8. Influence of coal mine tips on the chalk aquifer. Sampling methods for three dimensional sulphate infiltration study

    Energy Technology Data Exchange (ETDEWEB)

    Barrez, F.; Mania, J. [Polytech' Lille, Dept. Genie Civil, UMR CNRS 8107 (LML), 59 - Villeneuve d' Ascq (France); Mansy, J.L. [Lille-1 Univ., Lab. de Sedimentologie et de Geodynamique, UMR CNRS 8110 (PBDS), 59 - Villeneuve d' Ascq (France); Piwakowski, B. [Ecole Centrale de Lille, Groupe Electronique Acoustique IEMN-DOAE, UMR CNRS 8520, 59 - Villeneuve d' Ascq (France)

    2005-07-01

    The coal basin of the Nord-Pas-de-Calais region (France) shows a very strong deterioration of the Chalk aquifer quality. In order to better model the hydro-dynamism and to improve knowledge on the chemical interactions, sampling according to depth of the groundwater is undertaken. The low-flow sampling and the profiles of the in-situ physicochemical parameters allow the observation of various vertical heterogeneities of the aquifer. The areas where the coal mine tips are localised appear very interesting to study. The sulphates released by the pyrite oxidation allow a 'artificial tracing' and give a visualization of the flow as well as information on the implied chemical processes between the oxidizing and reducing zones. (authors)

  9. Drivers of abundance and community composition of benthic macroinvertebrates in Ottawa River sediment near Chalk River Laboratories

    International Nuclear Information System (INIS)

    The Ottawa River has received effluent from Chalk River Laboratories (CRL) for more than 60 years. Some radionuclides and contaminants released in effluents are bound rapidly to particles and deposited in bottom sediments where they may be biologically available to benthic invertebrates and other aquatic biota. As part of a larger ecological assessment, we assess the potential impact of contaminated sediments in the vicinity of CRL on local benthic community structure. Using bivariate and multivariate approaches, we demonstrate that CRL operations have had little impact on the local benthic community. Despite elevated anthropogenic radionuclide activity concentrations in sediment near CRL's process outfall, the benthic community is no less abundant or diverse than what is observed upstream at background levels. The Ottawa River benthic invertebrate community is structured predominantly by natural physical and biological conditions in the sediment, specifically sediment water content and organic content. These natural habitat conditions have a stronger influence on macroinvertebrate communities than sediment contamination. (author)

  10. Radon hazard and risk in Sussex, England and the factors affecting radon levels in dwellings in chalk terrain

    International Nuclear Information System (INIS)

    A survey was undertaken of radon levels in 1013 dwellings in Sussex, UK. A number of dwellings were identified with high radon levels in an area previously considered to offer low radon risk from geological sources. Multiple regression was used to determine the relative influence of the various geographical and building-related factors on indoor radon levels. The radon hazard, independent of building-related effects, was determined for each surveyed location by standardising radon measurements to a 'model' dwelling. These were entered into a geographic information system and related to surface geology. The highest radon levels were found to be associated with the youngest Chalk formations, Tertiary deposits and Clay-with-flints Quaternary deposits in the area. Radon potentials were also determined for the area which can be used to estimate radon risk and assist in environmental planning and development control. (authors)

  11. Influence of coal mine tips on the chalk aquifer. Sampling methods for three dimensional sulphate infiltration study

    International Nuclear Information System (INIS)

    The coal basin of the Nord-Pas-de-Calais region (France) shows a very strong deterioration of the Chalk aquifer quality. In order to better model the hydro-dynamism and to improve knowledge on the chemical interactions, sampling according to depth of the groundwater is undertaken. The low-flow sampling and the profiles of the in-situ physicochemical parameters allow the observation of various vertical heterogeneities of the aquifer. The areas where the coal mine tips are localised appear very interesting to study. The sulphates released by the pyrite oxidation allow a 'artificial tracing' and give a visualization of the flow as well as information on the implied chemical processes between the oxidizing and reducing zones. (authors)

  12. Drivers of abundance and community composition of benthic macroinvertebrates in Ottawa River sediment near Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Bond, M.J.; Rowan, D.; Silke, R.; Carr, J., E-mail: bondm@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2013-12-15

    The Ottawa River has received effluent from Chalk River Laboratories (CRL) for more than 60 years. Some radionuclides and contaminants released in effluents are bound rapidly to particles and deposited in bottom sediments where they may be biologically available to benthic invertebrates and other aquatic biota. As part of a larger ecological assessment, we assess the potential impact of contaminated sediments in the vicinity of CRL on local benthic community structure. Using bivariate and multivariate approaches, we demonstrate that CRL operations have had little impact on the local benthic community. Despite elevated anthropogenic radionuclide activity concentrations in sediment near CRL's process outfall, the benthic community is no less abundant or diverse than what is observed upstream at background levels. The Ottawa River benthic invertebrate community is structured predominantly by natural physical and biological conditions in the sediment, specifically sediment water content and organic content. These natural habitat conditions have a stronger influence on macroinvertebrate communities than sediment contamination. (author)

  13. Tilting oil-water contact in the chalk of Tyra Field as interpreted from capillary pressure data

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Rana, M.A.

    2010-01-01

    logging data in the remaining wells. A westerly dipping oil–water contact was found from logging data. Comparison of the depth-wise trends in normalized water saturation among the different wells indicates a regional pattern: in the western side of the field, the trends correspond to a situation of...... imbibition, where the free water level overlies an interval of residual oil, whereas in the eastern part of the field, the depth-wise trends in normalized water saturation correspond to a situation of drainage. The free water level apparently dips to the east due either to hydrodynamic action or to pressure......The Tyra Field in the central North Sea is located in Palaeogene and Upper Cretaceous chalk. It contains a natural gas zone underlain by an oil leg. Based on analysis of logs and core data from ten wells drilled prior to the field being put into production, normalized water saturation depth...

  14. 15N isotope biogeochemistry and natural denitrification process in groundwater: Application to the chalk aquifer of norther France

    International Nuclear Information System (INIS)

    The use of 15N natural isotope tracing in an aquifer contained within chalk rocks in northern France indicates that, under certain hydrogeological conditions, major denitrification occurs. At the boundary where the aquifer becomes confined, the nitrate concentrations decrease in the direction of groundwater flow accompanied by an exponential increase in 15N (expressed in δ15N) of the residual nitrate. This is characteristic of kinetic isotope effects, which accompany the reduction of the nitrate ion during denitrification. Hydrogeochemical and bacteriological observations confirm this process. Natural isotope tracing also permits this process to be distinguished from local dilution with nitrate-free water, which would entail a major drop in nitrate values without 15N isotopic enrichment. A model is proposed to explain the relatively small observed magnitude of the isotopic fractionation effect

  15. Contribution of piezometric measurement to knowledge and management of low water levels: examples on the chalk aquifer in the Champagne Ardennes region

    OpenAIRE

    Stollsteiner, P.; Bessiere, H.; Nicolas, J.; Allier, D.; Berthet, O.

    2015-01-01

    This article is based on a BRGM study on piezometric indicators, threshold values of discharge and groundwater levels for the assessment of potentially-exploitable water resources of chalky watersheds. A method for estimating low water levels based on groundwater levels is presented from three examples representing chalk aquifers with different cycles: annual, combined and interannual. The first is located in Picardy and the two others in the Champagne-Ardennes region. Piezometers with...

  16. Integrated seismic analysis of the Chalk Group in eastern Denmark—Implications for estimates of maximum palaeo-burial in southwest Scandinavia

    DEFF Research Database (Denmark)

    Nielsen, Lars; Boldreel, Lars Ole; Hansen, Thomas Mejer;

    2011-01-01

    The origin of the topography of southwest Scandinavia is subject to discussion. Analysis of borehole seismic velocity has formed the basis for interpretation of several hundred metres of Neogene uplift in parts of Denmark.Here, refraction seismic data constrain a 7.5km long P-wave velocity model of...... velocities are systematically higher than values of a chalk velocity curve determined in previous studies, and it is estimated that a significant part of the velocity anomaly may be explained by the presence of clay. The remaining velocity anomaly can be explained by 450–500m palaeo-burial of the Chalk Group....... The burial anomaly will be over-estimated by ~150–200m if the analysis is based on the average Chalk Group velocity and clay content is disregarded. Burial anomaly values of ~450–600m result if the strongest velocity contrast at ~600–650m depth is interpreted to be a result of diagenetic effects...

  17. Integrated seismic analysis of the Chalk Group in eastern Denmark—Implications for estimates of maximum palaeo-burial in southwest Scandinavia

    DEFF Research Database (Denmark)

    Nielsen, Lars; Boldreel, Lars Ole; Hansen, Thomas Mejer; Lykke-Andersen, Holger; Stemmerik, Lars; Surlyk, Finn; Thybo, Hans

    . The burial anomaly will be over-estimated by ~150–200m if the analysis is based on the average Chalk Group velocity and clay content is disregarded. Burial anomaly values of ~450–600m result if the strongest velocity contrast at ~600–650m depth is interpreted to be a result of diagenetic effects......The origin of the topography of southwest Scandinavia is subject to discussion. Analysis of borehole seismic velocity has formed the basis for interpretation of several hundred metres of Neogene uplift in parts of Denmark.Here, refraction seismic data constrain a 7.5km long P-wave velocity model of...... the Chalk Group below the Stevns peninsula, eastern part of the Danish Basin. The model contains four layers in the ~860m thick Chalk Group with mean velocities of 2.2km/s, 2.4km/s, 3.1km/s, and 3.9–4.3km/s. Sonic and gamma wireline log data from two cored boreholes represent the upper ~450m of the...

  18. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Final report, March 1996--September 1998

    Energy Technology Data Exchange (ETDEWEB)

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Carroll, R.E.; Groshong, R.H.; Jin, G.

    1998-12-01

    This project was designed to analyze the structure of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas to suggest ways in which oil recovery can be improved. The Eutaw Formation comprises 7 major flow units and is dominated by low-resistivity, low-contrast play that is difficult to characterize quantitatively. Selma chalk produces strictly from fault-related fractures that were mineralized as warm fluid migrated from deep sources. Resistivity, dipmeter, and fracture identification logs corroborate that deformation is concentrated in the hanging-wall drag zones. New area balancing techniques were developed to characterize growth strata and confirm that strain is concentrated in hanging-wall drag zones. Curvature analysis indicates that the faults contain numerous fault bends that influence fracture distribution. Eutaw oil is produced strictly from footwall uplifts, whereas Selma oil is produced from fault-related fractures. Clay smear and mineralization may be significant trapping mechanisms in the Eutaw Formation. The critical seal for Selma reservoirs, by contrast, is where Tertiary clay in the hanging wall is juxtaposed with poorly fractured Selma chalk in the footwall. Gilbertown Field can be revitalized by infill drilling and recompletion of existing wells. Directional drilling may be a viable technique for recovering untapped oil from Selma chalk. Revitalization is now underway, and the first new production wells since 1985 are being drilled in the western part of the field.

  19. COMPARISON OF THE TRADITIONAL CHALK AND BOARD LECTURE SYSTEM VERSUS POWER POINT PRESENTATION AS A TEACHING TECHNIQUE FOR TEACHING GROSS ANATOMY TO THE FIRST PROFESSIONAL MEDICAL STUDENTS

    Directory of Open Access Journals (Sweden)

    Nusrat

    2015-02-01

    Full Text Available Traditionally and conventionally, gross anatomy is taught by lectures and cadaveric dissection and the lectures are taken with chalk and board (C&B or chalk and talk method in, India. But there is always a debate over the most effective method of lecture delivery. AIM : The aim of this study was to compare the role and effectiveness chalk and board method versus power point presentation ( S tudent’s perception as a lecture delivering method for teaching gross anatomy. METHODS: This was a questionnaire based study where 140 out of 150 first professional MBBS students of Medical College Jammu, were asked to fill anonymously a questionnaire about their perceptions of these two lecture delivery methods. The results were analyzed to see if there was any preference of students for any particular method. RESULTS: The majority of the medical students (90.7% preferred PPT presentations, while only 9.3% of students preferred the lectures using chalkboard method. CONCLUSION: Most of the students clearly preferred and accepted the use of PPT presentations, as compared to conventional board teaching for delivery method. So teaching gross anatomy should be carefully amalgamated with use of power point in lecture hall.

  20. Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France)

    International Nuclear Information System (INIS)

    With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium (234U et 238U), thorium (230Th et 232Th), 226Ra and 222Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during α-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and α-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

  1. Impacts of climate change on in-stream nitrogen in a lowland chalk stream. An appraisal of adaptation strategies

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, P.G.; Butterfield, D.; Wade, A.J. [Aquatic Environments Research Centre, Department of Geography, University of Reading, Reading, RG6 6AB (United Kingdom); Wilby, R.L. [Environment Agency, Trentside Office, Scarrington Road, West Bridgford, Nottingham, NG2 5FA (United Kingdom)

    2006-07-15

    The impacts of climate change on nitrogen (N) in a lowland chalk stream are investigated using a dynamic modelling approach. The INCA-N model is used to simulate transient daily hydrology and water quality in the River Kennet using temperature and precipitation scenarios downscaled from the General Circulation Model (GCM) output for the period 1961-2100. The three GCMs (CGCM2, CSIRO and HadCM3) yield very different river flow regimes with the latter projecting significant periods of drought in the second half of the 21st century. Stream-water N concentrations increase over time as higher temperatures enhance N release from the soil, and lower river flows reduce the dilution capacity of the river. Particular problems are shown to occur following severe droughts when N mineralization is high and the subsequent breaking of the drought releases high nitrate loads into the river system. Possible strategies for reducing climate-driven N loads are explored using INCA-N. The measures include land use change or fertiliser reduction, reduction in atmospheric nitrate and ammonium deposition, and the introduction of water meadows or connected wetlands adjacent to the river. The most effective strategy is to change land use or reduce fertiliser use, followed by water meadow creation, and atmospheric pollution controls. Finally, a combined approach involving all three strategies is investigated and shown to reduce in-stream nitrate concentrations to those pre-1950s even under climate change. (author)

  2. Identification of a New Hesperornithiform from the Cretaceous Niobrara Chalk and Implications for Ecologic Diversity among Early Diving Birds.

    Directory of Open Access Journals (Sweden)

    Alyssa Bell

    Full Text Available The Smoky Hill Member of the Niobrara Chalk in Kansas (USA has yielded the remains of numerous members of the Hesperornithiformes, toothed diving birds from the late Early to Late Cretaceous. This study presents a new taxon of hesperornithiform from the Smoky Hill Member, Fumicollis hoffmani, the holotype of which is among the more complete hesperornithiform skeletons. Fumicollis has a unique combination of primitive (e.g. proximal and distal ends of femur not expanded, elongate pre-acetabular ilium, small and pyramidal patella and derived (e.g. dorsal ridge on metatarsal IV, plantarly-projected curve in the distal shaft of phalanx III:1 hesperornithiform characters, suggesting it was more specialized than small hesperornithiforms like Baptornis advenus but not as highly derived as the larger Hesperornis regalis. The identification of Fumicollis highlights once again the significant diversity of hesperornithiforms that existed in the Late Cretaceous Western Interior Seaway. This diversity points to the existence of a complex ecosystem, perhaps with a high degree of niche partitioning, as indicated by the varying degrees of diving specializations among these birds.

  3. Pre-operational HTO/HT surveys in the vicinity of the Chalk River Laboratories tritium extraction plant

    International Nuclear Information System (INIS)

    Surveys of the concentrations of HT and HTO in the atmosphere downwind of the Chalk River Laboratories reactor facilities were carried out in 1986 November, and in 1989 March, April and September under different conditions of air temperature, wind direction, and snow or vegetative cover. HT usually amounted to 1-5% of total tritium, but values up to 20% were observed, probably resulting from preferential removal of HTO. In all of the surveys, the greater persistence in the atmosphere of HT than of HTO was evident. The existing levels of HT are such that they will not be augmented significantly by chronic releases from the Tritium Extraction Plant (TEP) when it comes into operation. Hence, operation of the TEP will not facilitate studies of the environmental behaviour of chronically released HT. However, longer term studies of the distribution of HT from the existing facilities would be worthwhile. Soil and vegetation HTO levels in the study area are reported. Further studies of the distribution of tritium between the air, soil and vegetation in areas subjected to chronic exposure would be valuable

  4. Management of Legacy Spent Nuclear Fuel Wastes at the Chalk River Laboratories: The Challenges and Innovative Solutions Implemented - 13301

    International Nuclear Information System (INIS)

    AECL's Fuel Packaging and Storage (FPS) Project was initiated in 2004 to retrieve, transfer, and stabilize an identified inventory of degraded research reactor fuel that had been emplaced within in-ground 'Tile Hole' structures in Chalk River Laboratories' Waste Management Area in the 1950's and 60's. Ongoing monitoring of the legacy fuel storage conditions had identified that moisture present in the storage structures had contributed to corrosion of both the fuel and the storage containers. This prompted the initiation of the FPS Project which has as its objective to design, construct, and commission equipment and systems that would allow for the ongoing safe storage of this fuel until a final long-term management, or disposition, pathway was available. The FPS Project provides systems and technologies to retrieve and transfer the fuel from the Waste Management Area to a new facility that will repackage, dry, safely store and monitor the fuel for a period of 50 years. All equipment and the new storage facility are designed and constructed to meet the requirements for Class 1 Nuclear Facilities in Canada. (authors)

  5. Borehole television surveys and acoustic televiewer logging at the National Hydrology Research Institute's hydrogeological research area in Chalk River, Ontario

    International Nuclear Information System (INIS)

    This paper presents the results of studies of the fracture distribution and fracture orientation encountered in 23 boreholes at the National Hydrology Research Institute's Hydrogeological Research Area in Chalk River. Borehole television camera and acoustic televiewer data were used to determine: the fracture distribution as a function of depth; the aperture distribution as a function of depth; and, the predominant fracture sets. Fracture frameworks of the rock mass were constructed based on these data. The rock mass was found to be moderately to well fractured. Many open fractures were detected in the CR-series boreholes, especially in the upper 70 m. Three interconnecting, highly fractured zones are intersected by the CR-series boreholes between elevations of 96.80 m and 56.56 m, 34.91 m and -22.42 m, and -56.56 m and -61.31 m, while two interconnecting fracture zones are encountered by the FS-series boreholes between elevations 103.89 m and 96.64 m, and 108.20 m and 95.08 m. The predominant fracture sets strike east-west, northwest and indeterminably subhorizontal. The predominant set of veins strikes to the south. The subsurface fracture patterns and vein patterns were found to be similar to those observed on surface outcrops

  6. US team measurements during the June 1987 experimental HT release at the Chalk River Nuclear Laboratories, Ontario, Canada

    International Nuclear Information System (INIS)

    In June 1987, an experiment was performed at the Chalk River Nuclear Laboratories in Ontario, Canada, to study the oxidation of HT in the environment. The experiment involved a 30-minute release of 100 Ci of HT to the atmosphere at an elevation of one meter. The HTOHT ratios were shown to slowly increase downwind (/approximately/4 /times/ 10/sup /minus/5/ at 50 meters to almost 10/sup /minus/3 at 400 meters) as conversion of HT takes place. For several days after the release, HTO concentrations in the atmosphere remained elevated. Freeze-dried water from vegetation samples was found to be very low in HTO immediately after the release suggesting a very low direct uptake of HTO in air by vegetation. The tritiated water concentration increased during the first day, peaking during the second day (about 400 to 600 pCiml of water at 50 meters from the source) and decreasing by the end of the second day. The organically bound tritium continued to accumulate during the period following exposure (about 10 pCigm dry weight at 50 meters after two days). 4 refs., 6 figs., 2 tabs

  7. Diagnosing hydrological limitations of a land surface model: application of JULES to a deep-groundwater chalk basin

    Science.gov (United States)

    Le Vine, N.; Butler, A.; McIntyre, N.; Jackson, C.

    2016-01-01

    Land surface models (LSMs) are prospective starting points to develop a global hyper-resolution model of the terrestrial water, energy, and biogeochemical cycles. However, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. A diagnostic approach to model evaluation and improvement is taken here that exploits hydrological expert knowledge to detect LSM inadequacies through consideration of the major behavioural functions of a hydrological system: overall water balance, vertical water redistribution in the unsaturated zone, temporal water redistribution, and spatial water redistribution over the catchment's groundwater and surface-water systems. Three types of information are utilized to improve the model's hydrology: (a) observations, (b) information about expected response from regionalized data, and (c) information from an independent physics-based model. The study considers the JULES (Joint UK Land Environmental Simulator) LSM applied to a deep-groundwater chalk catchment in the UK. The diagnosed hydrological limitations and the proposed ways to address them are indicative of the challenges faced while transitioning to a global high resolution model of the water cycle.

  8. Projecting impacts of climate change on hydrological conditions and biotic responses in a chalk valley riparian wetland

    Science.gov (United States)

    House, A. R.; Thompson, J. R.; Acreman, M. C.

    2016-03-01

    Projected changes in climate are likely to substantially impact wetland hydrological conditions that will in turn have implications for wetland ecology. Assessing ecohydrological impacts of climate change requires models that can accurately simulate water levels at the fine-scale resolution to which species and communities respond. Hydrological conditions within the Lambourn Observatory at Boxford, Berkshire, UK were simulated using the physically based, distributed model MIKE SHE, calibrated to contemporary surface and groundwater levels. The site is a 10 ha lowland riparian wetland where complex geological conditions and channel management exert strong influences on the hydrological regime. Projected changes in precipitation, potential evapotranspiration, channel discharge and groundwater level were derived from the UK Climate Projections 2009 ensemble of climate models for the 2080s under different scenarios. Hydrological impacts of climate change differ through the wetland over short distances depending on the degree of groundwater/surface-water interaction. Discrete areas of groundwater upwelling are associated with an exaggerated response of water levels to climate change compared to non-upwelling areas. These are coincident with regions where a weathered chalk layer, which otherwise separates two main aquifers, is absent. Simulated water levels were linked to requirements of the MG8 plant community and Desmoulin's whorl snail (Vertigo moulinsiana) for which the site is designated. Impacts on each are shown to differ spatially and in line with hydrological impacts. Differences in water level requirements for this vegetation community and single species highlight the need for separate management strategies in distinct areas of the wetland.

  9. Hydrogeochemical processes affecting the migration of radionuclides in a fluvial sand aquifer at the Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    In the mid-1950's two experimental disposals of liquid radioactive waste containing about 700 curries of strontium-90 and cesium-137 were made into pits in sandy ground at one of the disposal areas at Chalk River Nuclear Laboratories. Since then, the wastes have migrated into two nearby aquifers and have chromatographically separated into strontium-90 and cesium-137 plumes moving at velocities less than that of the transporting groundwater. Analysis of radioactively contaminated aquifer sediments showed that most of the strontium-90 is exchangeably adsorbed, primarily to feldspars and layer silicates (mainly biotite); the rest is either specifically adsorbed to iron (III) and perhaps manganese (IV) oxhydroxides or fixed to unknown sinks. Less than one half of adsorbed cesium-137 is exchangeable with 0.5 m calcium chloride; the high levels of cesium-137 adsorption and fixation are probably due to its reaction with micaceous minerals. Complexation of strontium-90 and cesium-137 does not appear to be an important factor affecting their transport or adsorption. In studies of groundwater quality or pollution, dissolved oxygen and sulfide should be measured in addition to the redox potential since it allows independent assessment of the redox levels. The latter were found to affect the mobility of multivalent transition metals and nonmetals. (DN)

  10. PowerPoint or chalk and talk: Perceptions of medical students versus dental students in a medical college in India

    Directory of Open Access Journals (Sweden)

    Vikas Seth

    2010-08-01

    Full Text Available Vikas Seth, Prerna Upadhyaya, Mushtaq Ahmad, Vijay MogheDepartment of Pharmacology, Mahatma Gandhi Medical College, Jaipur, Rajasthan, IndiaPurpose: To assess students’ perceptions of the impact of PowerPoint (PPT presentations in lectures in comparison to the traditional chalk and talk method and lectures using ­transparencies and overhead projector (TOHP. The study analyzes the preferences for teaching aids of medical students versus dental students.Methods: Second year medical and dental undergraduates were asked to fill in a nine-item questionnaire about their perceptions of the three lecture delivery methods. Following analysis of the questionnaire the students were interviewed further. The results were analyzed separately for medical and dental students to see if there was any difference in their perceptions.Results: The majority of the medical students (65.33% preferred PPT presentations, while 15.16% of students preferred the lectures using chalkboard, and 19.51% preferred TOHP for teaching (P < 0.001. Of the dental students: 41.84% preferred chalkboard, 31.21% preferred TOHP, and 25.85% students preferred PPT presentations in the lectures (P < 0.05. Some important comments of the students were also recorded on interview which could be valuable for the medical teachers.Conclusion: The medical students clearly preferred the use of PPT presentations while the dental students did not. The study does not bring out evidence based superiority of any lecture delivery method. It appears that in the hands of a trained teacher any teaching aid would be appropriate and effective. This highlights the need for formal training in teaching technologies to develop good presentation skills and thus motivate the students.Keywords: audiovisual aids, medical education, lecture delivery methods, PowerPoint presentations, OHP, chalkboard

  11. Evaluation of five surface EM techniques for fracture detection and mapping at the Chalk River research area, Ontario

    International Nuclear Information System (INIS)

    Experimental field surveys were carried out with five surface electromagnetic (EM) systems at the Chalk River research area in 1980 and 1981. The purpose of the surveys was to test the usefulness of some new and a few existing EM systems for mapping fracture and shear zones in the highly resistive monzonite gneiss in the survey area. Fractures in the gneiss are often filled with water rich in ions, making the fractures medium to poor-grade conductors. The detection of these fractures by surface electromagnetic surveys depends on their conductance values (product of conductivity (s) and thickness (t)), the conductivity of the host rock, depth of the conductors, and strength, orientation, and frequency of the exciting field. The five EM systems used in the test surveys were: the local loop VLF-EM system; Max-Min II horizontal loop EM system; geonics EM-34 ground-mapping system; geonics EM-37; and, Maxi-Probe systems. Analysis of the field results shows that: the local loop VLF transmitter is a suitable substitute for Navy VLF stations; VLF and Max-Min II systems can detect poor conductors coincident with geologically defined lineaments and fracture zones, however, it is difficult at the moment to distinguish between near-vertical conductors in the bedrock and conductive overburden filling depressions in the bedrock surface; geonics EM-34 is not suitable in highly resistive terrain or in the presence of near-vertical conductors; and, the geonics EM-37 and Maxi-Probe systems detected possible subhorizontal conductors at depths of over 200 m. The presence of these could not be verified because of the lack of borehole control in those areas. An evaluation of the five systems indicates that VLF-EM and Max-Min II systems are most useful for detection of vertical and near-vertical fracture zones in the top 100 m, while EM-37 and Maxi-Probe systems are useful for detecting fracture zones at greater depths

  12. Understanding groundwater, surface water, and hyporheic zone biogeochemical processes in a Chalk catchment using fluorescence properties of dissolved and colloidal organic matter

    Science.gov (United States)

    Lapworth, D. J.; Gooddy, D. C.; Allen, D.; Old, G. H.

    2009-09-01

    Understanding groundwater-surface water (GW-SW) interaction in Chalk catchments is complicated by the degree of geological heterogeneity. At this study site, in southern United Kingdom, alluvial deposits in the riparian zone can be considered as a patchwork of varying grades and types with an equally varied lateral connectivity. Some display good connection with the river system and others good connection with the groundwater system and, by definition, poorer connectivity with the surface water. By coupling tangential flow fractionation (TFF) with fluorescence analysis we were able to characterize the organic matter in the river and hyporheic zone. There is a significant proportion of particulate and colloidal fluorescent organic matter (FOM) within the river system and at depth within the gravels beneath the river channel. At depth in the hyporheic zone, the surface water inputs are dampened by mixing with deeper groundwater FOM. The shallow (0-0.5 m below river bed) hyporheic zone is highly dynamic as a result of changing surface water inputs from upstream processes. Labile C in the form of protein-like FOM appears to be attenuated preferentially compared to fulvic-like fluorescence in the hyporheic zone compared to the adjacent gravel and sand deposits. These preliminary findings have important implications for understanding nutrient and trace element mobility and attenuation within the groundwater, surface water, and hyporheic zone of permeable Chalk catchments. Fluorescence analysis of dissolved organic matter has been shown to be a useful environmental tracer that can be used in conjunction with other methods to understand GW-SW processes within a permeable Chalk catchment.

  13. The impact of broadleaved woodland on water resources in lowland UK: I. Soil water changes below beech woodland and grass on chalk sites in Hampshire

    Directory of Open Access Journals (Sweden)

    J. Roberts

    2005-01-01

    Full Text Available The possible effects of broadleaved woodland on recharge to the UK Chalk aquifer have led to a study of evaporation and transpiration from beech woodland (Black Wood and pasture (Bridgets Farm, growing in shallow soils above chalk in Hampshire. Eddy correlation measurements of energy balance components above both the forest and the grassland enabled calculation of latent heat flux (evaporation and transpiration as a residual. Comparative measurements of soil water content and soil water potential in 9 m profiles under both forest and grassland found changes in soil water content down to 6 m at both sites; however, the soil water potential measurements showed upward movement of water only above a depth of about 2 m. Below this depth, water continued to drain and the soil water potential measurements showed downward movement of water at both sites, notwithstanding significant negative soil water potentials in the chalk and soil above. Seasonal differences occur in the soil water content profiles under broadleaved woodland and grass. Before the woodland foliage emerges, greater drying beneath the grassland is offset in late spring and early summer by increased drying under the forest. Yet, when the change in soil water profiles is at a maximum, in late summer, the profiles below woodland and grass are very similar. A comparison of soil water balances for Black Wood and Bridgets Farm using changes in soil water contents, local rainfall and evaporation measured by the energy balance approach allowed drainage to be calculated at each site. Although seasonal differences occurred, the difference in cumulative drainage below broadleaved woodland and grass was small.

  14. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Annual report, March 1996--March 1997

    Energy Technology Data Exchange (ETDEWEB)

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Groshong, R.H.

    1997-08-01

    Gilbertown Field is the oldest oil field in Alabama and produces oil from chalk of the Upper Cretaceous Selma Group and from sandstone of the Eutaw Formation along the southern margin of the Gilbertown fault system. Most of the field has been in primary recovery since establishment, but production has declined to marginally economic levels. This investigation applies advanced geologic concepts designed to aid implementation of improved recovery programs. The Gilbertown fault system is detached at the base of Jurassic salt. The fault system began forming as a half graben and evolved in to a full graben by the Late Cretaceous. Conventional trapping mechanisms are effective in Eutaw sandstone, whereas oil in Selma chalk is trapped in faults and fault-related fractures. Burial modeling establishes that the subsidence history of the Gilbertown area is typical of extensional basins and includes a major component of sediment loading and compaction. Surface mapping and fracture analysis indicate that faults offset strata as young as Miocene and that joints may be related to regional uplift postdating fault movement. Preliminary balanced structural models of the Gilbertown fault system indicate that synsedimentary growth factors need to be incorporated into the basic equations of area balance to model strain and predict fractures in Selma and Eutaw reservoirs.

  15. Advection dispersion modeling of tritium and chloride migration in a shallow sandy aquifer at the Chalk River Laboratories

    International Nuclear Information System (INIS)

    Elevated tritium, helium-3 and chloride concentrations have been measured in groundwaters in a shallow sandy aquifer draining a small lake at the Chalk River Laboratories (CRL), Ontario, Canada. The chloride in the lakewater recharge is 25 times greater than precipitation recharge and forms a continuous, concentrated source of contamination to the aquifer. Tritium (3H) concentrations in both lake and precipitation recharge are elevated owing to the operation of a research reactor on the CRL site and form a continuous spatially distributed source of contamination. The transport of tritium and chloride over the 600 m groundwater flowpath from the lake to the discharge zone are simulated using a 3-D advection-dispersion model. The model requires information on the contaminant input concentrations, the velocity field, dispersion parameters, hydrostratigraphy and boundary conditions. The two independent sets of concentration data provide complementary information to minimize problems associated with the unknown input concentration. The velocity field was estimated from a 3-D simulation of the groundwater flow system; dispersion parameters were estimated from analysis of a controlled natural-gradient tracer test performed previously at the site. The hydrostratigraphy and boundary geometry was characterized by visual logging of borehole sediments, grain size analyses and ground penetrating radar surveys. The abundance of hydrogeologic and geophysical information allowed simulation of the spatial distribution of chloride concentrations with a remarkable degree of accuracy. Simulated and measured peak chloride concentrations differed by less than 15%. The excellent agreement between the simulated and observed chloride concentrations facilitated further modelling of the source and migrational behavior of 3H within this aquifer. We have solved the inverse problem for the 3H source function and successfully modelled the 3H source as a stepwise function. Estimates of

  16. Implementation of agronomical and geochemical modules into a 3D groundwater code for assessing nitrate storage and transport through unconfined Chalk aquifer

    Science.gov (United States)

    Picot-Colbeaux, Géraldine; Devau, Nicolas; Thiéry, Dominique; Pettenati, Marie; Surdyk, Nicolas; Parmentier, Marc; Amraoui, Nadia; Crastes de Paulet, François; André, Laurent

    2016-04-01

    Chalk aquifer is the main water resource for domestic water supply in many parts in northern France. In same basin, groundwater is frequently affected by quality problems concerning nitrates. Often close to or above the drinking water standards, nitrate concentration in groundwater is mainly due to historical agriculture practices, combined with leakage and aquifer recharge through the vadose zone. The complexity of processes occurring into such an environment leads to take into account a lot of knowledge on agronomy, geochemistry and hydrogeology in order to understand, model and predict the spatiotemporal evolution of nitrate content and provide a decision support tool for the water producers and stakeholders. To succeed in this challenge, conceptual and numerical models representing accurately the Chalk aquifer specificity need to be developed. A multidisciplinary approach is developed to simulate storage and transport from the ground surface until groundwater. This involves a new agronomic module "NITRATE" (NItrogen TRansfer for Arable soil to groundwaTEr), a soil-crop model allowing to calculate nitrogen mass balance in arable soil, and the "PHREEQC" numerical code for geochemical calculations, both coupled with the 3D transient groundwater numerical code "MARTHE". Otherwise, new development achieved on MARTHE code allows the use of dual porosity and permeability calculations needed in the fissured Chalk aquifer context. This method concerning the integration of existing multi-disciplinary tools is a real challenge to reduce the number of parameters by selecting the relevant equations and simplifying the equations without altering the signal. The robustness and the validity of these numerical developments are tested step by step with several simulations constrained by climate forcing, land use and nitrogen inputs over several decades. In the first time, simulations are performed in a 1D vertical unsaturated soil column for representing experimental nitrates

  17. Chalk and computers

    DEFF Research Database (Denmark)

    Rasmussen, Lisa Rosén

    Since 1970 school books have first been supplemented by photocopies and later PDF files and the use of Internet sites. Chalkboards have been replaced by Smart Boards and notebooks by laptops and IPADS. Digital media has made its way into the classroom and into everyday school life. This has been...... highly connected to technological innovation that across the period has inspired hope as well as fear in teachers, pupils and parents. I take my starting point in the changing teaching aids of everyday school life to analyse how the technological development has been dealt with in the Danish school in...... the period 1970-2011. I wish to discuss how the analysis can benefit from a focus on the parallel introduction of thoughts concerning children’s culture, the competent child and the linkage of ‘Play & learn’. Looking at everyday life I also aim at discussing how the introduction of the new teaching...

  18. Mortality study of Canadian military personnel exposed to radiation: atomic test blasts and Chalk River nuclear reactor clean-ups, 1950's

    International Nuclear Information System (INIS)

    This report describes a historical cohort study of the group of Canadian military personnel exposed to radiation in the 1950s at atomic bomb test blasts in the U.S. and Australia, and at clean-up operations at the Chalk River Nuclear Laboratories. Overall and cause-specific mortality in the exposed group was compared to that of the control cohort of unexposed military personnel, matched on age, service, rank and trade. Analyses indicated no elevation in the exposed cohort, in overall or cause-specific mortality due to diseases associated with radiation. Since this study was restricted to an investigation of mortality, we must stress that we cannot generalize these results or conclusions to current morbidity experienced by the exposed cohort

  19. Development and maintenance of a telescoping debris flow fan in response to human-induced fan surface channelization, Chalk Creek Valley Natural Debris Flow Laboratory, Colorado, USA

    Science.gov (United States)

    Wasklewicz, T.; Scheinert, C.

    2016-01-01

    Channel change has been a constant theme throughout William L. Graf's research career. Graf's work has examined channel changes in the context of natural environmental fluctuations, but more often has focused on quantifying channel change in the context of anthropogenic modifications. Here, we consider how channelization of a debris flows along a bajada has perpetuated and sustained the development of 'telescoping' alluvial fan. Two-dimensional debris-flow modeling shows the importance of the deeply entrenched channelized flow in the development of a telescoping alluvial fan. GIS analyses of repeat (five different debris flows), high-resolution (5 cm) digital elevation models (DEMs) generated from repeat terrestrial laser scanning (TLS) data elucidate sediment and topographic dynamics of the new telescoping portion of the alluvial fan (the embryonic fan). Flow constriction from channelization helps to perpetuate debris-flow runout and to maintain the embryonic fan and telescoping nature of the alluvial fan complex. Embryonic fan development, in response to five debris flows, proceeds with a major portion of the flows depositing on the southern portion of the embryonic fan. The third through the fifth debris flows also begin to shift some deposition to the northern portion of the embryonic. The transfer of sediment from a higher portion of the embryonic fan to a lower portion continues currently on the embryonic fan. While channelized flow has been shown to be critical to the maintenance of the telescoping fan, the flow constriction has led to higher than background levels of sediment deposition in Chalk Creek, a tributary of the Arkansas River. A majority of the sediment from each debris flow is incorporated into Chalk Creek as opposed to being stored on the embryonic fan.

  20. The results from the second high-pressure melt ejection test completed in the Molten Fuel Moderator Interaction Facility at Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Nitheanandan, T.; Kyle, G.; O' Connor, R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2007-09-15

    The Canadian nuclear power generation industry, represented by the CANDU Owners Group (COG), is funding an experimental program at Chalk River Laboratories to study the interaction between the molten material ejected from the fuel channel and the moderator. These experiments are designed to address one of the very low probability postulated accident events considered for CANDU Pressurized Heavy Water Reactors (PHWRs), where an array of fuel channels contain the nuclear fuel and high-temperature, high-pressure coolant. Under severely restricted flow blockage conditions postulated in a fuel channel, the temperature excursion could result in fuel melting, consequential failure of the fuel channel, and ejection of the molten fuel at high pressures into the heavy water moderator at near atmospheric pressure. The objective of the experimental program is to demonstrate that a highly energetic Molten Fuel Moderator Interaction (MFMI) and associated high-pressure pulse can be ruled out. The second high-pressure melt ejection test using 22 kg of prototypical corium was completed recently at Chalk River Laboratories. The second test consisted of heating a thermite mixture of U, U{sub 3}O{sub 8}, Zr, and CrO{sub 3}, simulating the molten material expected in a fuel channel, inside a 1 m length of insulated pressure tube. Once the molten material reached the desired temperature of {approx}2400{sup o}C, the molten material was ejected into the surrounding tank of 63{sup o}C water. At the time of melt ejection, the static pressure in the test section was 3.35 MPa. The confinement vessel pressure reached a peak volume of 201 kPa following the rupture of the test section. The peak dynamic pressure measured on the inner vessel walls ranged between 0.7 MPa and 1 MPa. The dynamic pressure history, debris size, and the effects of the material interacting with tubes representing neighbouring fuel channels were investigated. (author)

  1. The results from the second high-pressure melt ejection test completed in the Molten Fuel Moderator Interaction Facility at Chalk River Laboratories

    International Nuclear Information System (INIS)

    The Canadian nuclear power generation industry, represented by the CANDU Owners Group (COG), is funding an experimental program at Chalk River Laboratories to study the interaction between the molten material ejected from the fuel channel and the moderator. These experiments are designed to address one of the very low probability postulated accident events considered for CANDU Pressurized Heavy Water Reactors (PHWRs), where an array of fuel channels contain the nuclear fuel and high-temperature, high-pressure coolant. Under severely restricted flow blockage conditions postulated in a fuel channel, the temperature excursion could result in fuel melting, consequential failure of the fuel channel, and ejection of the molten fuel at high pressures into the heavy water moderator at near atmospheric pressure. The objective of the experimental program is to demonstrate that a highly energetic Molten Fuel Moderator Interaction (MFMI) and associated high-pressure pulse can be ruled out. The second high-pressure melt ejection test using 22 kg of prototypical corium was completed recently at Chalk River Laboratories. The second test consisted of heating a thermite mixture of U, U3O8, Zr, and CrO3, simulating the molten material expected in a fuel channel, inside a 1 m length of insulated pressure tube. Once the molten material reached the desired temperature of ∼2400oC, the molten material was ejected into the surrounding tank of 63oC water. At the time of melt ejection, the static pressure in the test section was 3.35 MPa. The confinement vessel pressure reached a peak volume of 201 kPa following the rupture of the test section. The peak dynamic pressure measured on the inner vessel walls ranged between 0.7 MPa and 1 MPa. The dynamic pressure history, debris size, and the effects of the material interacting with tubes representing neighbouring fuel channels were investigated. (author)

  2. Risk-based Prioritization of Facility Decommissioning and Environmental Restoration Projects in the National Nuclear Legacy Liabilities Program at the Chalk River Laboratory - 13564

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Jerel G.; Kruzic, Michael [WorleyParsons, Mississauga, ON, L4W 4H2 (United States); Castillo, Carlos [WorleyParsons, Las Vegas, NV 89128 (United States); Pavey, Todd [WorleyParsons, Idaho Falls, ID 83402 (United States); Alexan, Tamer [WorleyParsons, Burnaby, BC, V5C 6S7 (United States); Bainbridge, Ian [Atomic Energy Canada Limited, Chalk River Laboratories, Chalk River, ON, K0J1J0 (Canada)

    2013-07-01

    Chalk River Laboratory (CRL), located in Ontario Canada, has a large number of remediation projects currently in the Nuclear Legacy Liabilities Program (NLLP), including hundreds of facility decommissioning projects and over one hundred environmental remediation projects, all to be executed over the next 70 years. Atomic Energy of Canada Limited (AECL) utilized WorleyParsons to prioritize the NLLP projects at the CRL through a risk-based prioritization and ranking process, using the WorleyParsons Sequencing Unit Prioritization and Estimating Risk Model (SUPERmodel). The prioritization project made use of the SUPERmodel which has been previously used for other large-scale site prioritization and sequencing of facilities at nuclear laboratories in the United States. The process included development and vetting of risk parameter matrices as well as confirmation/validation of project risks. Detailed sensitivity studies were also conducted to understand the impacts that risk parameter weighting and scoring had on prioritization. The repeatable prioritization process yielded an objective, risk-based and technically defendable process for prioritization that gained concurrence from all stakeholders, including Natural Resources Canada (NRCan) who is responsible for the oversight of the NLLP. (authors)

  3. Risk-based Prioritization of Facility Decommissioning and Environmental Restoration Projects in the National Nuclear Legacy Liabilities Program at the Chalk River Laboratory - 13564

    International Nuclear Information System (INIS)

    Chalk River Laboratory (CRL), located in Ontario Canada, has a large number of remediation projects currently in the Nuclear Legacy Liabilities Program (NLLP), including hundreds of facility decommissioning projects and over one hundred environmental remediation projects, all to be executed over the next 70 years. Atomic Energy of Canada Limited (AECL) utilized WorleyParsons to prioritize the NLLP projects at the CRL through a risk-based prioritization and ranking process, using the WorleyParsons Sequencing Unit Prioritization and Estimating Risk Model (SUPERmodel). The prioritization project made use of the SUPERmodel which has been previously used for other large-scale site prioritization and sequencing of facilities at nuclear laboratories in the United States. The process included development and vetting of risk parameter matrices as well as confirmation/validation of project risks. Detailed sensitivity studies were also conducted to understand the impacts that risk parameter weighting and scoring had on prioritization. The repeatable prioritization process yielded an objective, risk-based and technically defendable process for prioritization that gained concurrence from all stakeholders, including Natural Resources Canada (NRCan) who is responsible for the oversight of the NLLP. (authors)

  4. Model description of CHERPAC (Chalk River Environmental Research Pathways Analysis Code); results of testing with post-Chernobyl data from Finland

    International Nuclear Information System (INIS)

    CHERPAC (Chalk River Environmental Research Pathways Analysis Code), a time-dependent code for assessing doses from accidental and routine releases of radionuclides, has been under development since 1987. A complete model description is provide here with equations, parameter values, assumptions and information on parameter distributions for uncertainty analysis. Concurrently, CHERPAC has been used to participate in the two internal model validation exercises BIOMOVS (BIOspheric MOdel Validation Study) and VAMP (VAlidation of Assessment Model Predictions, a co-ordinated research program of the International Atomic Energy Agency). CHERPAC has been tested for predictions of concentrations of 137Cs in foodstuffs, body burden and dose over time using data collected after the Chernobyl accident of 1986 April. CHERPAC's results for the recent VAMP scenario for southern Finland are particularly accurate and should represent what the code can do under Canadian conditions. CHERPAC's predictions are compared with the observations from Finland for four and one-half years after the accident as well as with the results of the other participating models from nine countries. (author). 18 refs., 23 figs., 2 appendices

  5. Experimental study and mechanical modelling of the effects of water-driving in an oil saturated chalk. Application to the petroleum industry; Etude experimentale et modelisation mecanique des effets du balayage a l'eau dans une craie saturee d'huile. Application a l'industrie petroliere

    Energy Technology Data Exchange (ETDEWEB)

    Mata, C.

    2001-01-01

    The production of hydrocarbons may sometimes lead to compaction of the oil-reservoir layers with substantial collapse of the soil surface; this mechanism is usually mentioned as Subsidence. Classical remedy to this problem is to sustain the fluid pressure with the help of water injection. However, in presence of high porosity chalk (porosity > 30%), this technique does not give effective results: the subsidence rate at North Sea reservoirs (Ekofisk field), after injection, has remained unchanged. Some justify the subsistence in the chalk as caused by phenomena of dissolution of the carbonates; others think it is connected to the destruction of capillary menisci. In this research, we follow this second approach. This study is finalized to a better understanding of the compaction mechanisms in pure carbonates when water is injected. This is done by proposing -in micro-scale first and in macro-scale after- a physical model that agrees with empirical observations. In order to meet this target, IFP skills and experience in physical and chemical measurements (taken before, after and during mechanical tests) have proficiently joined ENPC laboratory (CERMMO) knowledge of micro and macro modelling. The soft rock studied is a Paris basin's white chalk (Craie de Guerville). Its physical and chemical characterisation (i.e.: silica content, porosity, permeability) is very similar to North Sea chalk, but Guerville chalk has never been in contact with oil and generally it crops out of the ground surface. Strength parameters of this rock have been first determined by standard triaxial tests. Three different saturation configurations have been examined: dry, fully oil-saturated and fully water-saturated. As literature clearly state, dry chalk is stronger than oil saturated chalk and the first two are largely stronger than water saturated chalk. Therefore uniaxial strain water injection tests have been performed on oil saturated samples. Results, coupled with previous physical

  6. U–Pb, Rb–Sr, and U-series isotope geochemistry of rocks and fracture minerals from the Chalk River Laboratories site, Grenville Province, Ontario, Canada

    International Nuclear Information System (INIS)

    Highlights: • AECL evaluates Chalk River Laboratories site as potential nuclear waste repository. • Isotope-geochemical data for rocks and fracture minerals at CRL site are reported. • Zircons from gneiss and granite yielded U–Pb ages of 1472 ± 14 and 1045 ± 6 Ma. • WR Rb–Sr and Pb–Pb systems do not show substantial large-scale isotopic mobility. • U-series and REE data do not support oxidizing conditions at depth in the past 1 Ma. - Abstract: As part of the Geologic Waste Management Facility feasibility study, Atomic Energy of Canada Ltd. (AECL) is evaluating the suitability of the Chalk River Laboratories (CRL) site in Ontario, situated in crystalline rock of the southwestern Grenville Province, for the possible development of an underground repository for low- and intermediate-level nuclear waste. This paper presents petrographic and trace element analyses, U–Pb zircon dating results, and Rb–Sr, U–Pb and U-series isotopic analyses of gneissic drill core samples from the deep CRG-series characterization boreholes at the CRL site. The main rock types intersected in the boreholes include hornblende–biotite (±pyroxene) gneisses of granitic to granodioritic composition, leucocratic granitic gneisses with sparse mafic minerals, and garnet-bearing gneisses with variable amounts of biotite and/or hornblende. The trace element data for whole-rock samples plot in the fields of within-plate, syn-collision, and volcanic arc-type granites in discrimination diagrams used for the tectonic interpretation of granitic rocks. Zircons separated from biotite gneiss and metagranite samples yielded SHRIMP-RG U–Pb ages of 1472 ± 14 (2σ) and 1045 ± 6 Ma, respectively, in very good agreement with widespread Early Mesoproterozoic plutonic ages and Ottawan orogeny ages in the Central Gneiss Belt. The Rb–Sr, U–Pb, and Pb–Pb whole-rock errorchron apparent ages of most of the CRL gneiss samples are consistent with zircon U–Pb age and do not indicate

  7. Contribution of piezometric measurement to knowledge and management of low water levels: examples on the chalk aquifer in the Champagne Ardennes region

    Science.gov (United States)

    Stollsteiner, P.; Bessiere, H.; Nicolas, J.; Allier, D.; Berthet, O.

    2015-04-01

    This article is based on a BRGM study on piezometric indicators, threshold values of discharge and groundwater levels for the assessment of potentially-exploitable water resources of chalky watersheds. A method for estimating low water levels based on groundwater levels is presented from three examples representing chalk aquifers with different cycles: annual, combined and interannual. The first is located in Picardy and the two others in the Champagne-Ardennes region. Piezometers with annual cycles, used in these examples, are supposed to be representative of the aquifer hydro-dynamics. Except for multi-annual systems, the analysis between discharge measurements at a hydrometric station and groundwater levels measured at a piezometer representative of the main aquifer, leads to relatively precise and satisfactory relationships within a chalky context. These relationships may be useful for monitoring, validation, extension or reconstruction of the low water flow data. On the one hand, they allow definition of the piezometric levels corresponding to the different alert thresholds of river discharges. On the other hand, they clarify the proportions of low surface water flow from runoff or drainage of the aquifer. Finally, these correlations give an assessment of the minimum flow for the coming weeks. However, these correlations cannot be used to optimize the value of the exploitable water resource because it seems to be difficult to integrate the value of the effective rainfall that could occur during the draining period. Moreover, in the case of multi-annual systems, the solution is to attempt a comprehensive system modelling and, if it is satisfactory, using the simulated values to get rid of parasites or running the model for forecasting purposes.

  8. Results of detailed ground geophysical surveys for locating and differentiating waste structures in waste management area 'A' at Chalk River Laboratories, Ontario

    International Nuclear Information System (INIS)

    Waste Management Area 'A' (WMA 'A'), located in the outer area of the Chalk River Laboratories (CRL) was in use as a waste burial site from 1946 to 1955. Waste management structures include debris-filled trenches, concrete bunkers and miscellaneous contaminated solid materials, and ditches and pits used for liquid dispersal. In order to update historical records, it was proposed to conduct detailed ground geophysical surveys to define the locations of waste management structures in WMA 'A', assist in planning of the drilling and sampling program to provide ground truth for the geophysics investigation and to predict the nature and locations of unknown/undefined shallow structures. A detailed ground geophysical survey grid was established with a total of 127 grid lines, oriented NNE and spaced one metre apart. The geophysical surveys were carried out during August and September, 1996. The combination of geophysical tools used included the Geonics EM61 metal detector, the GSM-19 magnetometer/gradiometer and a RAMAC high frequency ground penetrating radar system. The geophysical surveys were successful in identifying waste management structures and in characterizing to some extent, the composition of the waste. The geophysical surveys are able to determine the presence of most of the known waste management structures, especially in the western and central portions of the grid which contain the majority of the metallic waste. The eastern portion of the grid has a completely different geophysical character. While historical records show that trenches were dug, they are far less evident in the geophysical record. There is clear evidence for a trench running between lines 30E and 63E at 70 m. There are indications from the radar survey of other trench-like structures in the eastern portion. EM61 data clearly show that there is far less metallic debris in the eastern portion. The geophysical surveys were also successful in identifying previously unknown locations of waste

  9. The results from the second high-pressure melt ejection test completed in the molten fuel moderator interaction facility at Chalk River Laboratories

    International Nuclear Information System (INIS)

    For a Candu reactor and under severely restricted flow blockage conditions postulated in a fuel channel, the temperature excursion could result in fuel melting, consequential failure of the fuel channel, and ejection of the molten fuel at high pressures into the heavy water moderator at near atmospheric pressure. The objective of the experimental program is to demonstrate that a highly energetic Molten Fuel Moderator Interaction (MFMI) and associated high-pressure pulse can be ruled out for a Candu reactor. The second high-pressure melt ejection test using 22 kg of prototypical corium was completed recently at Chalk River Laboratories. The second test consisted in heating a thermite mixture of U, U3O8, Zr, and CrO3, simulating the molten material expected in a fuel channel, inside a 1 m length of insulated pressure tube. Once the molten material reached the desired temperature of about 2400 C degrees, the molten material was ejected into the surrounding tank of 63 C water. At the time of melt ejection, the static pressure in the test section was 3.35 MPa. The confinement vessel pressure reached a peak value of 201 kPa following the rupture of the test section. The peak dynamic pressure measured on the inner vessel walls ranged between 0.7 MPa and 1 MPa. The total debris collected inside the tank was 22.65 kg. The debris inside the inner tank consists of corium, quartz and Zircar. The majority of the corium particles were less than 1 mm in diameter and the calculated value of the mean size of the debris appears to be 0.581 mm. An analysis of the confinement vessel gas inventory indicated 17.6% hydrogen

  10. The results from the second high-pressure melt ejection test completed in the molten fuel moderator interaction facility at Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Nitheanandan, T.; Kyle, G.; O' Connor, R. [Chalk River Laboratories, Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2007-07-01

    For a Candu reactor and under severely restricted flow blockage conditions postulated in a fuel channel, the temperature excursion could result in fuel melting, consequential failure of the fuel channel, and ejection of the molten fuel at high pressures into the heavy water moderator at near atmospheric pressure. The objective of the experimental program is to demonstrate that a highly energetic Molten Fuel Moderator Interaction (MFMI) and associated high-pressure pulse can be ruled out for a Candu reactor. The second high-pressure melt ejection test using 22 kg of prototypical corium was completed recently at Chalk River Laboratories. The second test consisted in heating a thermite mixture of U, U{sub 3}O{sub 8}, Zr, and CrO{sub 3}, simulating the molten material expected in a fuel channel, inside a 1 m length of insulated pressure tube. Once the molten material reached the desired temperature of about 2400 C degrees, the molten material was ejected into the surrounding tank of 63 C water. At the time of melt ejection, the static pressure in the test section was 3.35 MPa. The confinement vessel pressure reached a peak value of 201 kPa following the rupture of the test section. The peak dynamic pressure measured on the inner vessel walls ranged between 0.7 MPa and 1 MPa. The total debris collected inside the tank was 22.65 kg. The debris inside the inner tank consists of corium, quartz and Zircar. The majority of the corium particles were less than 1 mm in diameter and the calculated value of the mean size of the debris appears to be 0.581 mm. An analysis of the confinement vessel gas inventory indicated 17.6% hydrogen.

  11. Impedance imaging in core analysis. Imaging of phase distributions in samples of natural cores of North Sea chalk containing conducting as well as non-conducting fluids. Part: 1-3

    Energy Technology Data Exchange (ETDEWEB)

    Laursen, S. [DTU, Inst. for Kemi (Denmark)] Moeller Nielsen, C. [DTU, Inst. for Energiteknik (Denmark)

    1997-12-31

    The present report documents the efforts to develop an impedance method for determining the distribution of the water saturation in a chalk core sample. Measurement of this distribution during a displacement process will make it possible to make numerical simulations of the process which may in turn reveal important rock parameters. The impedance method is one among other methods to determine saturation profiles in a research programme on rock parameters with participants from Danmarks Tekniske Universitet, DTU, and Danmarks og Groenlands Geologiske Undersoegelse, GEUS. The other methods investigated are nmr-scanning and {gamma}-logging. (au)

  12. Results of detailed ground geophysical surveys for locating and differentiating waste structures in waste management area 'A' at Chalk River Laboratories, Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Tomsons, D.K.; Street, P.J.; Lodha, G.S

    1999-07-01

    Waste Management Area 'A' (WMA 'A'), located in the outer area of the Chalk River Laboratories (CRL) was in use as a waste burial site from 1946 to 1955. Waste management structures include debris-filled trenches, concrete bunkers and miscellaneous contaminated solid materials, and ditches and pits used for liquid dispersal. In order to update historical records, it was proposed to conduct detailed ground geophysical surveys to define the locations of waste management structures in WMA 'A', assist in planning of the drilling and sampling program to provide ground truth for the geophysics investigation and to predict the nature and locations of unknown/undefined shallow structures. A detailed ground geophysical survey grid was established with a total of 127 grid lines, oriented NNE and spaced one metre apart. The geophysical surveys were carried out during August and September, 1996. The combination of geophysical tools used included the Geonics EM61 metal detector, the GSM-19 magnetometer/gradiometer and a RAMAC high frequency ground penetrating radar system. The geophysical surveys were successful in identifying waste management structures and in characterizing to some extent, the composition of the waste. The geophysical surveys are able to determine the presence of most of the known waste management structures, especially in the western and central portions of the grid which contain the majority of the metallic waste. The eastern portion of the grid has a completely different geophysical character. While historical records show that trenches were dug, they are far less evident in the geophysical record. There is clear evidence for a trench running between lines 30E and 63E at 70 m. There are indications from the radar survey of other trench-like structures in the eastern portion. EM61 data clearly show that there is far less metallic debris in the eastern portion. The geophysical surveys were also successful in identifying

  13. Results from the fourth high-pressure melt ejection test completed in the molten fuel moderator interaction facility at Chalk River Laboratories

    International Nuclear Information System (INIS)

    The fourth high-pressure melt ejection test using prototypical corium was completed at Chalk River Laboratories. This test was one of four tests planned by Atomic Energy of Canada Limited to study the potential for energetic interaction between molten fuel and water. The experiments were designed to address one of the very low probability postulated accident events considered for Candu Pressurized Heavy Water Reactors (PHWRs). The accident event considered is the severe reduction in the coolant flow to a single channel. This reduction could result from a blockage in the flow or a break in the inlet piping to a fuel channel. If the reduction in the flow is severe (approaching complete cessation of the flow), the fuel channel will overheat and fail. Such a failure is not predicted to propagate to other fuel channels; the scenario is terminated with the emergency coolant injection. Under severely restricted flow blockage conditions, the temperature excursion could result in fuel melting. Conservative safety analysis assessments consider the implications of the worst-case scenario, which can involve the ejection of the molten material from the fuel channel into the heavy-water moderator. The predictions are that the melt will be finely fragmented and will transfer energy to the moderator as it is dispersed, creating a modest pressure pulse in the calandria vessel. The high-pressure melt ejection experiments funded by the Candu Owners Group have been performed to confirm these predictions and to show that a highly energetic 'steam explosion, ' and associated high-pressure pulse, is not possible. The high-pressure melt ejection test described here consisted of heating 12.5 kg of a thermite mixture U, UO2, Zr, and CrO3, representing the molten material in a fuel channel, inside an insulated pressure tube. When the molten material reached the desired temperature of ∼2400 deg.C, the pressure inside the tube was raised to about 10.5 MP a, and the pressure tube failed due

  14. Low-level radioactive river sediment particles originating from the Chalk river nuclear site carry a mixture of radionuclides and metals

    Energy Technology Data Exchange (ETDEWEB)

    Lind, Ole Christian; Cagno, Simone; Salbu, Brit [Norwegian University of Life Sciences - NMBU, Center of Excellence in Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Aas (Norway); Falkenberg, Gerald [Photon science, DESY, Hamburg (Germany); Janssens, Koen; Nuyts, Gert; Vanmeert, Frederik [AXIL, Department of Chemistry, University of Antwerpen (Belgium); Jaroszewicz, Jakub [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Priest, Nicholas D.; Audet, Marc [Nuclear Science Division, AECL Chalk River Laboratories (Canada)

    2014-07-01

    The Chalk River Laboratory of Atomic Energy of Canada Ltd., site is located on the Ottawa River approximately 200 km northwest of Ottawa, Canada. The site has two large research reactors: NRX, which operated from 1947 to 1991 and NRU, which continues to operate and is used to produce a significant fraction of the world's supply of medical isotopes. During the course of the operation of the NRX reactor small quantities of radioactive particles were discharged to the Ottawa River through a process sewer discharge pipe. These are now located in river bed sediments within a 0.08 km² area close to the discharge pipe. In the present study, selected particles were isolated from riverbed sediments. These were then characterized by environmental scanning electron microscopy with energy dispersive micro X-ray analysis (ESEM-EDX). This was undertaken to obtain information on particle size, structure and the distribution of elements across particle surfaces. Based on the results of ESEM-EDX, particles were selected for X-ray absorption nano-tomography analysis, which provides videos showing the 3D density distribution of the particles. Furthermore, 2D and 3D Synchrotron Radiation based X-ray techniques (micro-X-ray fluorescence; micro-XRF, micro-X-ray absorption near edge spectroscopy; micro-XANES and micro-X-ray diffraction; micro-XRD) with submicron resolution (beam size 0.5 μm) were employed to investigate the elemental and phase composition (micro-XRF/XRD) and oxidation states (micro-XANES) of matrix elements with high spatial resolution and sensitivity. Results show that the particles investigated so far varied according to: 1) <~40 μm diameter sized U fuel particles similar in structure to particles observed from Chernobyl and Krasnoyarsk-26 and 2) larger particles with diameters up to several hundred μm. The larger particles comprised a matrix of low density, sediment material with high density inclusions that contained a range of metals including Cu, Cr, As

  15. An Investigation into the Transportation of Irradiated Uranium/Aluminum Targets from a Foreign Nuclear Reactor to the Chalk River Laboratories Site in Ontario, Canada - 12249

    International Nuclear Information System (INIS)

    This investigation required the selection of a suitable cask and development of a device to hold and transport irradiated targets from a foreign nuclear reactor to the Chalk River Laboratories in Ontario, Canada. The main challenge was to design and validate a target holder to protect the irradiated HEU-Al target pencils during transit. Each of the targets was estimated to have an initial decay heat of 118 W prior to transit. As the targets have little thermal mass the potential for high temperature damage and possibly melting was high. Thus, the primary design objective was to conceive a target holder to dissipate heat from the targets. Other design requirements included securing the targets during transportation and providing a simple means to load and unload the targets while submerged five metres under water. A unique target holder (patent pending) was designed and manufactured together with special purpose experimental apparatus including a representative cask. Aluminum dummy targets were fabricated to accept cartridge heaters, to simulate decay heat. Thermocouples were used to measure the temperature of the test targets and selected areas within the target holder and test cask. After obtaining test results, calculations were performed to compensate for differences between experimental and real life conditions. Taking compensation into consideration the maximum target temperature reached was 231 deg. C which was below the designated maximum of 250 deg. C. The design of the aluminum target holder also allowed generous clearance to insert and unload the targets. This clearance was designed to close up as the target holder is placed into the cavity of the transport cask. Springs served to retain and restrain the targets from movement during transportation as well as to facilitate conductive heat transfer. The target holder met the design requirements and as such provided data supporting the feasibility of transporting targets over a relatively long period of time

  16. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama -- Year 2. Annual report, March 1997--March 1998

    Energy Technology Data Exchange (ETDEWEB)

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Carroll, R.E.

    1998-09-01

    Gilbertown Field is the oldest oil field in Alabama and has produced oil from fractured chalk of the Cretaceous Selma Group and glauconitic sandstone of the Eutaw Formation. Nearly all of Gilbertown Field is still in primary recovery, although waterflooding has been attempted locally. The objective of this project is to analyze the geologic structure and burial history of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas in order to suggest ways in which oil recovery can be improved. Indeed, the decline of oil production to marginally economic levels in recent years has made this type of analysis timely and practical. Key technical advancements being sought include understanding the relationship of requisite strain to production in Gilbertown reservoirs, incorporation of synsedimentary growth factors into models of area balance, quantification of the relationship between requisite strain and bed curvature, determination of the timing of hydrocarbon generation, and identification of the avenues and mechanisms of fluid transport.

  17. Impedance imaging in core analysis. Imaging of phase distributions in samples of natural cores of North Sea chalk containing conducting as well as non-conducting fluids. Part 1: Development of prototype measurement cell

    Energy Technology Data Exchange (ETDEWEB)

    Moeller Nielsen, C. [DTU, Inst. for Kemi (Denmark); Lauersen, S. [DTU, Lab. for Energiteknik (Denmark)

    1996-12-31

    To make reservoir simulations it is necessary to know such parameter functions as the capillary pressure curve, relative permeabilities etc. These are difficult to measure in chalk by means of traditional techniques because of the low permeability. In the present approach a displacement process is studied in detail and computer simulation with reservoir simulators can be used to determine parameter functions. To do this, however, it is necessary to know the developments of saturation profiles during the experiment. Different methods are tested in the programme. NMR-scanning and {gamma}-logging are methods where straight rays penetrate the sample and are partly absorbed. In electric current imaging an electric field is induced in the sample and detected at the surface. There are several benefits of this method compared with the others: There are no special safety requirements in contrast to work with radiation; No expensive and limited available equipment is needed unlike NMR; There are no intrinsic procedures slowing the method. There are, however, also drawbacks: Making measurements on a core sample implies the application of a large number of minute electrodes. To do this an implementation has to be derived from scratch; The inverse problem, i.e. the determination of the field inside the sample from surface measurements, is more difficult than the inverse problem of straight ray absorption. In the present report the development of an experimental technique is described. In part II of the report the interpretation of the experimental results will be discussed. (EG) 21 refs.

  18. Importance du phénomène de dissolution-cristallisation sur le fluage d'une craie blanche Importance of the Dissolution-Crystallization Phenomenon on Creep in a White Chalk

    Directory of Open Access Journals (Sweden)

    Djebbi M.

    2006-11-01

    Full Text Available Une étude de fluage de craie blanche a été menée pour des contraintes de confinement allant jusqu'à 12 MPa dans des configurations de contrainte isotrope ou avec léger déviateur. Il est montré l'importance du phénomène de dissolution sur la variation de volume locale du système. Celle-ci suit une loi du type At alpha avec alpha de l'ordre de 0,5 lorsqu'il n'y a pas d'écoulement, et de l'ordre de 0,65 quand l'échantillon est soumis à un écoulement. Il est alors proposé le modèle de Bathurst comme mécanisme de déformation. Creep in a white chalk was analyzed for confining pressures of up to 12 MPa in isotropic stress configurations or with a slight deviatoric stress. The importance of this dissolution phenomenon was shown for the local variation in the volume of the system. This variation follows a law of the At alpha type, with alpha being a 0. 5 order when there is no flow and a 0. 65 order when the sample is subjected to flow. The Bathurst model is then proposed as the deformation mechanism.

  19. Use of borehole-geophysical logs and hydrologic tests to characterize crystalline rock for nuclear-waste storage, Whiteshell Nuclear Research Establishment, Manitoba, and Chalk River Nuclear Laboratory, Ontario, Canada

    International Nuclear Information System (INIS)

    A number of borehole methods were used in the investigation of crystalline rocks at Whiteshell Nuclear Research Establishment and Chalk River Nuclear Laboratory in Canada. The selection of a crystalline-rock mass for the storage of nuclear waste likely will require the drilling and testing of a number of deep investigative boreholes in the rock mass. Although coring of at least one hole in each new area is essential, methods for making in-situ geophysical and hydrologic measurements can substitute for widespread coring and result in significant savings in time and money. Borehole-geophysical logging techniques permit the lateral extrapolation of data from a core hole. Log response is related to rock type, alteration, and the location and character of fractures. The geophysical logs that particularly are useful for these purposes are the acoustic televiewer and acoustic waveform, neutron and gamma, resistivity, temperature, and caliper. The acoustic-televiewer log of the borehole wall can provide high resolution data on the orientation and apparent width of fractures. In situ hydraulic tests of single fractures or fracture zones isolated by packers provide quantitative information on permeability, extent, and interconnection. The computer analysis of digitized acoustic waveforms has identified a part of the waveform that has amplitude variations related to permeabilities measured in the boreholes by packer tests. 38 refs., 37 figs., 4 tabs

  20. 27 CFR 9.52 - Chalk Hill.

    Science.gov (United States)

    2010-04-01

    ... Quadrangle Map”; (10) Then northerly for approximately 1.3 miles along Mark West Road (which becomes Porter Creek Road), then northeasterly for approximately 1.7 miles on Porter Creek Road to its intersection with the unnamed medium duty road that parallels Porter Creek in Section 12, T. 8 N., R. 8 W.;...

  1. Chalk: composition, diagenesis and physical properties

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2007-01-01

    entry pressure, and elastic moduli are consequences of primary sediment composition and of subsequent diagenetic history as caused by microbial action, burial stress, temperature, and pore pressure. Porosity is a main determining factor for other properties. For a given porosity, the specific surface of...... the sediment controls permeability and capillary entry pressure. As diagenesis progresses, the specific surface is less and less due to the calcite component and more and more due to the fine-grained silicates, as a reflection of the coarsening and cementation of the calcite crystals. The elastic...... depth, rate of burial, and over-pressuring. These factors cause the stress, temperature and pore-pressure to increase at different rates during burial in different localities....

  2. Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France); Desequilibres des series de l'uranium dans les aquiferes: quantification des mecanismes de transport de l'uranium et de ses descendants: cas de l'aquifere de la craie (Champagne, France)

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, A

    2005-09-15

    With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium ({sup 234}U et {sup 238}U), thorium ({sup 230}Th et {sup 232}Th), {sup 226}Ra and {sup 222}Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during {alpha}-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and {alpha}-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

  3. Elaboration of an Elasto-Plastic Model for High Porosity Chalks. Application to the Compaction of Petroleum Reservoirs Elaboration d'un modèle de comportement élasto-plastique pour les craies très poreuses. Application à la compaction des réservoirs pétroliers

    Directory of Open Access Journals (Sweden)

    Shahrour I.

    2006-11-01

    Full Text Available This paper presents a study of the compaction of petroleum reservoirs applied to very porous carbonate rocks such as chalk. In production estimates made in reservoir engineering, the processing of the mechanical problem is often greatly simplified. Good modelling of how materials behave gives special consideration to the influence of mechanical deformations on fluid recovery. After an analysis of the mechanical behaviour of very porous chalks, an elastoplastic behaviour model is derived so as to reproduce the principal experimental observations. This behaviour model can then be used to perform local simulations of the mechanical behaviour of a reservoir under- going depletion and thus to demonstrate the importance of the stress path and the initial stress state on the deformation of materials and hence on the recovery rate. Dans les applications pétrolières, les études de la compaction des roches réservoirs interviennent dans l'estimation des quantités de fluide récupérables et de la subsidence induite par la déplétion du champ de production. Dans la première partie du travail, nous montrons qu'à partir de l'équation linéarisée de la conservation de la masse de fluide, il est possible d'exprimer un taux de récupération distinguant les contributions respectives du fluide et de la roche. En ingénierie de réservoirs, l'hypothèse d'un chemin de contrainte prépondérant dans le milieu de production permet d'exprimer la contribution de la déformation de la roche au moyen de la compressibilité volumique des pores selon ce chemin. Le taux de récupération obtenu est alors dépendant du chemin de contrainte. Lorsque le chemin de contrainte dans le réservoir n'est pas homogène, il est alors nécessaire de connaître la loi de comportement mécanique du matériau étudié. Dans le cas des carbonates très poreux, nous désirons montrer l'influence liée au choix du chemin de contrainte sur les estimations obtenues par une m

  4. Magnetic field measurements on the Chalk River superconducting cyclotron

    International Nuclear Information System (INIS)

    Midplane magnetic fields have been measured for the modified flutter pole geometry of the cyclotron magnet at forty-eight excitations with mean inductions spanning the range two to five tesla. Midplane fringing fields have been measured both through the cryostat and beyond the yoke at selected excitations. Measurements of yoke temperature effects and hysteresis are also described

  5. Who Teaches with More Than Chalk and Talk?

    OpenAIRE

    Cynthia Lay Harter; Becker, William E.; Michael Watts

    1999-01-01

    Probit analysis is used to investigate factors that affect instructors' choices of teaching methodologies in introductory economics. The results show that instructor gender, percent of work time devoted to teaching, and the school's Carnegie classification are important determinants. Also, although class size is not an important determinant in the choice of instructional techniques used in the classroom, it is important in the choice of print materials and out-of-class assignments.

  6. The Chalk River Nuclear Laboratories contingency plan -a brief description

    International Nuclear Information System (INIS)

    A brief description of the contingency plan which deals with both the on-site and off-site consequences of a serious nuclear accident is given. The off-site consequences of different size releases and the subsequent action taken by employees, radiation protection experts, municipal, Provincial and Federal authorities is described and the interaction of the various groups is discussed. (author)

  7. Facilities for Waste Management at Chalk River, Canada

    International Nuclear Information System (INIS)

    The waste disposal areas used by the Atomic Energy of Canada Limited are situated in a rock basin filled with glacial till and sand, draining into the Ottawa River. Low-activity liquid effluent is run into pits in the sand, which are filled with small rocks to prevent contact of liquid with the air. Medium- level liquid is mixed with cement in drums which are stacked and totally enclosed in concrete trenches; medium-level solids are buried in concrete-lined trenches; high-level solids are placed in holes lined with steel or concrete piping. Special facilities are provided for organic liquids and bottled wastes. Details will be given of the structural work and procedures, with an outline of the results of environmental monitoring. (author)

  8. Stylolites, porosity, depositional texture, and silicates in chalk facies sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Borre, Mai K.

    2007-01-01

    matrix shows recrystallization but only minor pore-filling cement, whereas microfossils are cemented. Cementation in Gorm and Tyra is thus partial and has apparently not been retarded by opal-controlled pore-water. A possible explanation is that, due to the relatively high temperature, silica has...

  9. Higher education institutions: as different as chalk and cheese?

    NARCIS (Netherlands)

    Huisman, Jeroen

    2000-01-01

    Asserting that there is a lack of attention to operationalising and measuring institutional diversity in higher education, this paper attempts to fill the gap. Bearing on the use of the concept of diversity in biology, a model is proposed to conceptualise and measure diversity. The basic principles

  10. Fluid substitution studies for North Sea chalk logging data

    DEFF Research Database (Denmark)

    Gommesen, Lars; Mavko, G.; Mukerji, T.;

    2002-01-01

    show that the Kuster-Toksöz model fails to predict the presence of hydrocarbons. The Gassmann prediction for the near and potentially invaded zone corresponds more closely to logging data, than the Gassmann prediction for the far, virgin zone. We hereby conclude that the Gassmann theory predicts...

  11. Nuclear safety review process at Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    Atomic Energy of Canada has a extensive health and safety organization in place to protect its facilities and employees, and the public in general. This consists of the operating groups who have the primary responsibility for safety, and a network of safety advisory groups and safety review committees for providing the broadest possible overview of facility safety. A rigorous multi-stage nuclear safety review process is specified by Company policies and procedures to ensure that all activities have undergone thorough review and have satisfied predetermined requirements. For major facilities, this includes up to five distinct safety review and licensing stages with approvals being required from both the Atomic Energy Control Board and AECL Nuclear Safety Advisory Committee for the major steps in the process. In addition, each approved operating facility, including its experimental program, undergoes regular independent safety review and assessment of ongoing operation. The role of the AECL Safety and Reliability Directorate in these activities is described. Other aspects of the overall safety review process including the development of safety criteria, the development of standard safety documentation, and the application of quality assurance to safety assessment activities are discussed. Some thinking is presented on possible future directions in the continuing evolution of these overall safety processes

  12. Elastic and electric properties of North Sea Chalk

    DEFF Research Database (Denmark)

    Olsen, Casper

    bjergartsfysiske modeller til forudsigelse af Biot’s koefficient ud fra porøsitet og én lydhastighed og hans resultater tyder på at Berryman’s udbredte ”Selfconsistent Model” er mindre velegnet til det formål, mens at de simplere Isoframe og Bound-averaging metoder giver bedre resultater. Dvorkin’s partikel...

  13. The Turnover Process at Chalk River Laboratories from Operations to Decommissioning

    International Nuclear Information System (INIS)

    Canadian Nuclear Laboratories (CNL) has 200 facilities that account for approximately 2 million square feet of building space. Currently there are 23 facilities undergoing various stages of Decommissioning. An additional 30 facilities are scheduled to be turned over to Decommissioning in 2016. CNL is currently restructuring to transition to a Government Owned/Contractor Operated (GoCo) organization and there will be a focus to accelerate the Decommissioning of legacy facilities on site. In the past, facilities were shutdown and left in various configurations with limited documentation or limited staff knowledge of the status of the facility at the start of Decommissioning. Recently, guidelines have been developed to ensure that any facility being turned over is put into a proper and documented safe shutdown configuration. This paper will look at CNL's process for turnover of facilities from Operations to Decommissioning and identify some of the key Lessons Learned. The turnover of nuclear facilities, administrative and support buildings, components or areas from Operations to Decommissioning needs to be documented and managed to ensure Health, Safety, Security and Environmental (HSSE) risks are identified, eliminated or effectively controlled. At CNL, the turnover document Table of Contents is: Introduction and Purpose; Facility Boundaries; Known Deficiencies; Facility Status; Shutdown Status; Hazards; System/Equipment; Drawings/Maps/Records; Significant Environmental Aspects (SEAs); Interface; and other Transfer Documentation. The transfer documentation specifically covers: - Defined boundaries of the facility, building, component or area at the time of turnover; - Identification of all deficiencies associated with the facility, building, component or area and the person, after turnover, who will be responsible for correcting them; - Confirmation of the status of the facility, building, component or area at the time of turnover with respect to: - The status of the Preliminary Decommissioning Plan (PDP). If the PDP is not current then it should be revised before Facilities Decommissioning accepts full responsibility for the facility, building, component or area; - Details of Shutdown activities (e.g. isolations, draining, decontamination, etc.); - Hazards that remain; - Significant environmental aspects and operational controls; - Details of system/equipment that remain energized or continue to perform their design function (e.g. holding tank still containing radiological liquid, etc.); - Updated drawings and equipment specifications; - Status of Engineering Change Control (ECC) that are in progress; - Safety Related Systems (SRS) list; - Fire code and building code violations or deficiencies; - Maintenance schedule; - Inventory of Nuclear Materials; - Governing documents e.g. Criticality Safety Document, Preliminary Decommissioning Plan, Environmental Assessment, Safety Analysis Report, Facility Authorization, etc.; - Outstanding Regulatory commitments; - Information on any required amendments to the Site License; and - Listing of all documentation and records to be included with the Transfer Certificate. Key responsibilities are laid out defining what is required from each party and other groups involved in the transfer of the facility. (authors)

  14. Updated follow-up of long-term Chalk River employees

    International Nuclear Information System (INIS)

    Data on the follow-up of CRNL employees who died during employment or after retirement have been updated to 1982 December 31. Updated tables on mortality for AECL participants in the 1953 NRX clean-up and in the 1958 NRU decontamination are also included in this report. Preliminary mortality data on two other groups are presented here for (a) female employees of CRNL, 1966-1982 and (b) male employees of CRNL who have accumulated lifetime occupational doses of 0.2 Sv (20 rem) or more. Data on types of fatal cancer recorded for long-term male CRNL employees over the period 1966-1982 are also given. No statistically significant increases in cancer deaths were found in any of the groups analyzed

  15. How burial diagenesis of chalk sediments controls sonic velocity and porosity

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2003-01-01

    higher. Upon burial, the sediments lose porosity by mechanical compaction, and concurrently, the calcite particles recrystallize into progressively more equant shapes. High compaction rates may keep the particles in relative motion, whereas low compaction rates allow the formation of contact cement...

  16. Summary of loops in the Chalk River NRX and NRU reactors

    International Nuclear Information System (INIS)

    The design and operating parameters of the high pressure, high temperature light water loops in the NRX and NRU reactors are presented to assist experimenters reviewing these facilities for their experiments. The NRX and NRU reactor design and operating data of interest to the experimenters are also presented. (author)

  17. Calcareous nannofossils from the Boreal upper Campanian-Maastrichtian Chalk of Denmark

    DEFF Research Database (Denmark)

    Thibault, Nicolas Rudolph

    2010-01-01

    , the Rordal-1 borehole and the Rordal quarry section, North Jylland. The moderately-preserved nannofossil assemblages consist of a total of 138 species, comprising several rarely-documented species. several species that were recently described from lower latitudes, two new species of heterococcolith...

  18. From ooze to sedimentary rock, the first diagenetic processes affecting the chalk of eastern Denmark

    DEFF Research Database (Denmark)

    Moreau, Julien; Boussaha, Myriam; Nielsen, Lars;

    -resolution seismic reflection profiles, high-resolution wireline logs and sedimentological data from a fully cored borehole, and field information from quarry and coastal cliff exposures were taken to inform about early diagenetic features. This integrated approach for the first time enabled placing different...

  19. Fair Use or Copyright Infringement: Off-Air Video in the Classroom. Chalk Talk.

    Science.gov (United States)

    Journal of Law and Education, 1996

    1996-01-01

    Educators today have access to technologies that provide both new information sources and new methods of copying, adapting, and transporting information into the classroom. The purpose of this article is to help educators properly interpret and apply copyright law to the use of video as an instructional tool. (38 footnotes) (MLF)

  20. Implementing the AECL decommissioning quality assurance program at the Chalk River and Whiteshell Laboratories

    International Nuclear Information System (INIS)

    This paper describes the approach and progress in developing, implementing and maintaining a quality assurance (QA) program for decommissioning at the nuclear facilities managed by Atomic Energy of Canada Limited (AECL). Decommissioning activities conducted by AECL are varied in nature, so the QA program must provide adequate flexibility, while maintaining consistency with accepted quality standards. Well-written documentation adhering to the applicable decommissioning standards is a key factor. Manager commitment and input during the writing of the documentation are also important to ensure relevance of the QA program and effectiveness of implementation. Training in the use of the quality assurance plan and procedures is vital to the understanding of the QA program. Beyond the training aspect there is a need for the quality assurance program to be supported by a QA subject expert who is able to advise the group in implementing the Quality Program with consistency over the range of decommissioning work activities and to provide continual assessment of the quality assurance program for efficiency and effectiveness, with a concomitant continuous improvement process. (author)

  1. Radiochemistry Lab Decommissioning and Dismantlement. AECL, Chalk River Labs, Ontario, Canada

    International Nuclear Information System (INIS)

    Atomic Energy of Canada (AECL) was originally founded in the mid 1940's to perform research in radiation and nuclear areas under the Canadian Defense Department. In the mid 50's The Canadian government embarked on several research and development programs for the development of the Candu Reactor. AECL was initially built as a temporary site and is now faced with many redundant buildings. Prior to 2004 small amounts of Decommissioning work was in progress. Many reasons for deferring decommissioning activities were used with the predominant ones being: 1. Reduction in radiation doses to workers during the final dismantlement, 2. Development of a long-term solution for the management of radioactive wastes in Canada, 3. Financial constraints presented by the number of facilities shutdown that would require decommissioning funds and the absence of an approved funding strategy. This has led to the development of a comprehensive decommissioning plan that is all inclusive of AECL's current and legacy liabilities. Canada does not have a long-term disposal site; therefore waste minimization becomes the driving factor behind decontamination for decommissioning before and during dismantlement. This decommissioning job was a great learning experience for decommissioning and the associated contractors who worked on this project. Throughout the life of the project there was a constant focus on waste minimization. This focus was constantly in conflict with regulatory compliance primarily with respect to fire regulations and protecting the facility along with adjacent facilities during the decommissioning activities. Discrepancies in historical documents forced the project to treat every space as a contaminated space until proven differently. Decommissioning and dismantlement within an operating site adds to the complexity of the tasks especially when it is being conducted in the heart of the plant. This project was very successful with no lost time accidents in over one hundred thousand hours worked, on schedule and under budget despite some significant changes throughout the decommissioning phases. The actual cost to decommission this building will come in under 9 million dollars vs. an estimated 14.5 million dollars. This paper will cover some of the unique aspects of dismantling a radioactive building that has seen pretty much every element of the periodic table pass through it with the client requirement focused on minimization of radioactive waste volumes

  2. Importance of fines in smart water enhanced oil recovery (SmW-EOR) for chalk outcrops

    DEFF Research Database (Denmark)

    Chakravarty, Krishna Hara; Fosbøl, Philip Loldrup; Thomsen, Kaj

    2015-01-01

    In SmW-EOR it is generally believed that precipitation of brines must be avoided since it can have a negative impact on the SmW sweep efficiency. But substitution of Mg2+ by Ca2+ on calcite surfaces (a well-accepted phenomenon) can change the brine combination and enhance the possibility of fine ...

  3. Uncertainty of climate change impact on groundwater reserves - Application to a chalk aquifer

    Science.gov (United States)

    Goderniaux, Pascal; Brouyère, Serge; Wildemeersch, Samuel; Therrien, René; Dassargues, Alain

    2015-09-01

    Recent studies have evaluated the impact of climate change on groundwater resources for different geographical and climatic contexts. However, most studies have either not estimated the uncertainty around projected impacts or have limited the analysis to the uncertainty related to climate models. In this study, the uncertainties around impact projections from several sources (climate models, natural variability of the weather, hydrological model calibration) are calculated and compared for the Geer catchment (465 km2) in Belgium. We use a surface-subsurface integrated model implemented using the finite element code HydroGeoSphere, coupled with climate change scenarios (2010-2085) and the UCODE_2005 inverse model, to assess the uncertainty related to the calibration of the hydrological model. This integrated model provides a more realistic representation of the water exchanges between surface and subsurface domains and constrains more the calibration with the use of both surface and subsurface observed data. Sensitivity and uncertainty analyses were performed on predictions. The linear uncertainty analysis is approximate for this nonlinear system, but it provides some measure of uncertainty for computationally demanding models. Results show that, for the Geer catchment, the most important uncertainty is related to calibration of the hydrological model. The total uncertainty associated with the prediction of groundwater levels remains large. By the end of the century, however, the uncertainty becomes smaller than the predicted decline in groundwater levels.

  4. Electrical tortuosity, Kozeny’s factor and cementation factor modelled for chalk

    DEFF Research Database (Denmark)

    Katika, Konstantina; Fabricius, Ida Lykke

    2015-01-01

    calculate permeability based on electrical resistivity data. We also calculate the permeability based on a simple porosity model. Finally, we redefine Kozeny’s factor, c, using Carman’s model based on tortuosity and the model based on porosity. This resulted in a third modelled permeability, which describes...

  5. Genetic architecture of grain chalk in rice and interactions with a low phytic acid locus

    Science.gov (United States)

    Grain quality characteristics have a major impact on the value of the harvested rice crop. In addition to grain dimensions which determine market classes, translucency is also required for the highest grain quality. Over the last several years, the USA rice industry has been concerned about the incr...

  6. Liberal And General Studies In Further Education: Voices From The ‘Chalk Face’

    OpenAIRE

    Simmons, Robin; Waugh, Colin; Hopkins, Mike; Perry, Liz; Stafford, Roy

    2014-01-01

    This paper presents initial findings from research investigating an important but largely neglected facet of the history of Further Education (FE) – the Liberal Studies and General Studies (LS/GS) movement. Drawing on historical documents and interview data from a group of former LS/GS lecturers, the paper provides important insights into some of the key events and initiatives between the 1950s-1980s, which led to the rise and eventual fall of the LS/GS movement, and seeks to capture the voic...

  7. OE Management at Research Technology Operations, Chalk River Laboratories, AECL, Canada

    International Nuclear Information System (INIS)

    Brief description of nuclear facility. A nuclear installation consisting of a 130 MW research reactor and 13 licensed nuclear facilities, staffed by ∼2600 employees, on three distinct sites. Main activities include: (1) Reactor development; (2) CRL nuclear operations; (3) Research and development; (4) Isotope production; (5) Waste management and decommissioning. Overview of OE arrangements. A centralized OE group that is permanently resourced and trained to support the organization. The group is spread over two time zones and supported by a cadre of permanently dedicated OE coordinators and action tracking coordinators throughout the organization

  8. Suction and time effects on the behaviour of a reservoir chalk

    OpenAIRE

    Priol, Grégoire; De Gennaro, Vincenzo; Delage, Pierre; COLLIN, Frédéric; Charlier, Robert

    2006-01-01

    Oil reservoir rocks contain various immiscible fluids (oil, water and gas) and they are submitted to elevated temperatures in the oilfield. Hence, they exhibit a typical coupled behaviour where multiphysics and coupled Thermo-Hydro-Mechanical aspects are predominant. This paper presents some results from researches carried out within the PASACHALK 2 European funded collaborative research. In this research dedicated to subsidence problems in the North sea Ekofisk oilfield, the behaviour of a r...

  9. The ecology of chalk-stream invertebrates studied in a recirculating stream

    OpenAIRE

    LADLE M.; Welton, J. S.

    1984-01-01

    To study and qualify the factors influencing interactions between various trophic levels in natural hard-water streams, a recirculating artificial stream channel was constructed. This structure has enabled patterns of population change of stream fauna to be observed under partially controlled physical and chemical conditions. Initial colonization of the substratum by invertebrates and subsequent succession was studied along with depth distribution and growth and production studies of inverteb...

  10. The movement of tritium from the Chalk River Liquid Disposal Area

    International Nuclear Information System (INIS)

    A groundwater survey has shown that tritium, as tritiated water, has migrated from the Liquid Disposal Area and spread beneath 70 acres of adjoining land. An estimated 8,250 curies beneath South Swamp and Perch Lake Swamp are advancing towards Perch Lake. A weak 'front' has already reached the lake but the concentrations are expected to rise to ten times the present value in two years. A further increase is anticipated in four years time. (author)

  11. Porosity Variation in Cenozoic and Upper Chalk from the Ontong Java Pleateau

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine

    1997-01-01

    Porosity was obtained from matrix- and intraparticle porosity assessed from image analysis of backscattered electron micrographs of 3000x and 300x magnification. Comparing porosity assessed from image analysis with porosity measured by index properties, it was seen that image analysis data at 3000x...

  12. Results from impression packer technique for location of fissures in boreholes in white chalk, Mors, Denmark

    International Nuclear Information System (INIS)

    In connection with site investigations to evaluate the possibility of geological disposal of radioactive waste in a salt dome a Hydrogeological Programme was carried out. A number of bore holes were drilled to depths of 550 m. Geological and hydrogeological investigations were performed. The hydrogeological tests were carried out as packer tests, bottomhole tests using one packer, or straddle-packer test using two packers. In connection with these tests a rubber sleeve was installed over the packer and sidewall impressions of the hole were taken. Irregularities such as faults and fissures and possibly solution features were localized. The paper describes the method, procedure, equipment and the results achieved

  13. Beyond Chalk and Talk: Strategies for a New Introductory Economics Curriculum.

    Science.gov (United States)

    Rishi, Meenakshi

    1998-01-01

    Factors in development of a new introductory economics course, primarily for nonmajors, are discussed. These include selection of course content to capture student interest and reflect societal change, creation of a more stimulating classroom environment, and use of three cooperative learning activities on poverty, inflation, and budget deficits.…

  14. Phosphorus dynamics and productivity in a sewage-impacted lowland chalk stream

    Science.gov (United States)

    Palmer-Felgate, Elizabeth J.; Jarvie, Helen P.; Williams, Richard J.; Mortimer, Robert J. G.; Loewenthal, Matthew; Neal, Colin

    2008-03-01

    SummaryHourly in situ phosphorus, conductivity, turbidity, dissolved oxygen, pH, and chlorophyll measurements were collected from January 2004 to November 2006 for the River Kennet, 2 km downstream of a sewage effluent inlet. Excess carbon dioxide pressure (EpCO 2) was calculated from continuous pH and spot alkalinity measurements. EpCO 2 and dissolved oxygen were used to estimate rates of photosynthesis and respiration. These parameters were examined alongside flow, water temperature and solar radiation to explore controls on phosphorus dynamics and in-stream productivity. Diurnal, event and seasonal patterns were observed in phosphorus concentrations. The diurnal and seasonal variations appeared to be related to the upstream sewage treatment works. The event patterns coincided with periods of high flow, and were attributed to diffuse sources. Chlorophyll behaved independently of phosphorus concentration and returned to baseline levels before photosynthesis rate. This indicated that, during the period of study, in-stream productivity was primarily controlled by aquatic plants other than phytoplankton.

  15. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge

    DEFF Research Database (Denmark)

    Anderskouv, Kresten; Surlyk, Finn

    2011-01-01

    , including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab­sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites...

  16. NMR permeability estimators in "chalk" carbonate rocks obtained under different relaxation times and MICP size scalings

    Science.gov (United States)

    Rios, Edmilson Helton; Figueiredo, Irineu; Moss, Adam Keith; Pritchard, Timothy Neil; Glassborow, Brent Anthony; Domingues, Ana Beatriz Guedes; Azeredo, Rodrigo Bagueira de Vasconcellos

    2016-04-01

    The effect of the selection of different nuclear magnetic resonance (NMR) relaxation times for permeability estimation is investigated for a set of fully brine-saturated rocks acquired from Cretaceous carbonate reservoirs in the North Sea and Middle East. Estimators that are obtained from the relaxation times based on the Pythagorean means are compared with estimators that are obtained from the relaxation times based on the concept of a cumulative saturation cutoff. Select portions of the longitudinal (T1) and transverse (T2) relaxation-time distributions are systematically evaluated by applying various cutoffs, analogous to the Winland-Pittman approach for mercury injection capillary pressure (MICP) curves. Finally, different approaches to matching the NMR and MICP distributions using different mean-based scaling factors are validated based on the performance of the related size-scaled estimators. The good results that were obtained demonstrate possible alternatives to the commonly adopted logarithmic mean estimator and reinforce the importance of NMR-MICP integration to improving carbonate permeability estimates.

  17. Development and irradiation testing of Al-U3Si2 at Chalk River Laboratories

    International Nuclear Information System (INIS)

    Mini-elements containing Al-64 wt% U3Si2 (3.15 gU/cm3), with three discrete U3Si2 particle-size distributions, have been irradiated up to 93 at% burnup in the NRU reactor. The uranium silicide (U-7.0Si) was used in the as-cast condition, and contained up to 4 wt% free uranium in the U3Si2 matrix. Post-irradiation examinations (PIE) of the high-burnup elements have been recently completed. PIE included underwater and hot-cell examinations, immersion density measurements, neutron radiography, optical and scanning electron microscopy (SEM) with wavelength dispersion X-ray (WDX) analysis, and computerized image analysis of the fission-gas bubble-size distributions. The results show that the Al-U3Si2 swelled less than Al-U3Si fuel previously irradiated under similar conditions in NRU, and no significant swelling dependence on particle-size distribution was observed. Al-U3Si2 core volume increases ranged from 4.2 to 4.7 vol%, compared to 5.8 to 6.8 vol% for Al-U3Si fuel with identical uranium loadings. SEM examinations revealed that the U3Si2 (U-7.0Si) particles contained regions with relatively ordered, very dense populations of sub-micron fission-gas bubbles. In contrast, the gas bubbles are randomly distributed within U3Si (U-3.96Si) particles, vary widely in size, and small bubbles coalesce to form larger bubbles. The capability of U3Si2 to retain fission gas in small bubbles accounts for the lower swelling. (author)

  18. Teaching Principles of Economics without "Chalk and Talk": The Experience of CNU Online.

    Science.gov (United States)

    Vachris, Michelle Albert

    1999-01-01

    Discusses the Christopher Newport University (Virginia) [CNU] online program in which students can complete their general education required courses and earn four-year undergraduate degrees online. Addresses the effects of technology on students and the problems encountered in an online environment. Includes reactions by George Bredon and Howard…

  19. Diagenesis of silica-rich mounded chalk, the Coniacian Arnager Limestone, Denmark

    DEFF Research Database (Denmark)

    Buus Madsen, Heine; Stemmerik, Lars; Surlyk, Finn

    precipitation of opal-CT. The opal-CT formed at temperatures around 17°C, the precipitation lowered the silica activity and the Si/Al ratio of the pore water, resulting in precipitation of clinoptilolite, feldspar and smectite. Calcite formed synchronouslywith the latest clinoptilolite.Minoramounts of quartz...... precipitated in pore water with low silica activity during maximum burial, probably to depths of 200-250 m. The dissolution of sponge spicules and decomposition of the sponge tissue also resulted in the release of Ba2+, Sr2+,Mg2+, Ca2+ and CO3 2-, facilitating precipitation of barite and dolomite...... consist of twomicrofacies, spiculiticwackestone and bioturbated spiculitic wackestone, containing 10-22% and 7-12% moulds after spicules, respectively. Subsequent to deposition and shallow burial, dissolution of siliceous sponge spicules increased the silica activity of the pore water and initiated...

  20. Experience with low-level waste incineration at Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    Construction of a full-scale Waste Treatment Center to volume reduce, stabilize and immobilize CRNL's low-level radioactive wastes for improved storage or disposal is essentially complete. A batch-operated starved-air incinerator for solid combustible waste is one of the processes installed in this facility. Commissioning of this prototype incinerator with inactive waste began in 1980 August and concluded in 1981 December; twenty-two 1-tonne charges (i.e. ''burns'') were completed during that phase. Since then, it has routinely processed most of the current arisings of combustible low-level radioactive waste (LLW) at CRNL. To date, about 1400 m3 of LLW containing up to about 20 mCi/m3 (740 MBq/m3) of mixed activity have been incinerated in 113 burns. Overall performance has remained good during the nearly 3000 h of service with LLW feed. All operational and maintenance functions have been performed without contamination or exposure problems. Particulate beta-gamma stack releases have routinely remained less than 1 /sigma phi/Ci (37 kBq) per burn. The incinerator consistently produces a fully satisfactory inert ash product to an average volume reduction factor greater than 150:1

  1. Analysis and Applications of Microorganisms from a Chalk Oil Reservoir in the North Sea

    OpenAIRE

    Kaster, Krista Michelle

    2009-01-01

    Ekofisk er et krittsteinsreservoar i den norske sektoren av Nordsjøen, og dette reservoaret inneholdt aktive og diverse mikrobielle samfunn. Mikrobielle aktiviteter kan medføre skadelige effekter som surgjøring av reservoarer, men også ha nytteeffekter som ved økt oljeutvinning. Formålet med dette studiet var å karakterisere mikrobielle samfunn i Ekofisk reservoaret, samt å framskaffe innsikt i mikrobielle mekanismer som var viktige for a) å kontrollere reservoarforsuring og b) kunne medvirke...

  2. Diagenesis of Flint and Porcellanite in the Maastrichtian Chalk at Stevns Klint, Denmark

    DEFF Research Database (Denmark)

    Buus Madsen, Heine; Stemmerik, Lars

    2010-01-01

    more stable and ordered megaquartz in irregular voids indicates that silica gel and/or opal-CT transformed to the -quartz phases, microquartz, lutecite, chalcedony, and megaquartz, through the dissolution–precipitation process (Ostwald ripening). These results motivate a conceptual model in which the...... that precipitation of the flint precursor can be controlled by a combination of an abundant biosiliceous source and high microbial activity in the sediments immediately below the seafloor. Flint is therefore likely to reflect deposition in a narrow interval at relatively shallow depths and therefore...

  3. Experimental Study of Bacterial Penetration into Chalk Rock: Mechanisms and Effect on Permeability

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Shapiro, Alexander; Eliasson Lantz, Anna;

    2014-01-01

    Bacterial selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery, as bacteria can plug the water-swept zones of a reservoir, thus altering the flow paths and improving sweep efficiency. However, complete understanding of the penetration...

  4. Oxidation and dispersion of HT in the environment: The August 1986 field experiment at Chalk River

    International Nuclear Information System (INIS)

    The short-range environmental dispersion and oxidation of a release of tritiated hydrogen (HT) to the atmosphere has been studied in a field experiment. Emphasis was placed on the processes leading to the appearance of tritiated water (HTO) vapor in the atmosphere because HTO is much more radiotoxic than HT. The following conclusions were reached: No evidence was found for the rapid conversion of HT to HTO in the atmosphere; HTO observed in air, during and after the release, arose mainly from HT oxidation in the soil followed by emission of HTO; HT deposition velocities to soil ranged from 0.041 cm s-1 to 0.13 cm s-1, consistent with previous chamber measurements; the rate of HTO loss from soil, averaged over 21 d, was less than 1% h-1; and HTO concentrations in vegetation water initially increased with time after the release, then by 48 h decreased exponentially at a rate similar to soils

  5. Chemical properties of organic soils developed from lacustrine chalk near the lakes Strzeszowskie, Sitno, and Sierakowo (Western Pomerania, north Poland)

    OpenAIRE

    Jarnuszewski Grzegorz

    2015-01-01

    The genesis of organic soils is closely connected with water. The occurrence of carbonate deposits in the central and lower part of organic soil profile points to the link between their genesis and post-glacial lakes. The studies conducted in the years 2009–2012 focused on organic soils near lakes: Strzeszowskie, Sitno (Myśliborskie Lakeland) and Sierakowo (Ińskie Lakeland), north Poland. The goal of the present study was to characterize chemical properties of organic soils developed on carbo...

  6. Modeling Various Teaching Methods in a Faculty of Education in Science Education: Chalk and Talk, Virtual Labs or Hovercrafts

    Science.gov (United States)

    Laronde, Gerald; MacLeod, Katarin

    2012-01-01

    This research was conducted with 291 Junior/Intermediate (J/I) pre-service teachers in a ubiquitous laptop Bachelor of Education program at Nipissing University. The authors modeled a lesson using three different teaching styles using flight as the content medium, a specific expectation found in the Ontario Ministry of Education grade six Science…

  7. Dealing with Historical Discrepancies: The Recovery of National Research Experiment (NRX) Reactor Fuel Rods at Chalk River Laboratories (CRL) - 13324

    International Nuclear Information System (INIS)

    Following the 1952 National Research Experiment (NRX) Reactor accident, fuel rods which had short irradiation histories were 'temporarily' buried in wooden boxes at the 'disposal grounds' during the cleanup effort. The Nuclear Legacy Liabilities Program (NLLP), funded by Natural Resources Canada (NRCan), strategically retrieves legacy waste and restores lands affected by Atomic Energy of Canada Limited (AECL) early operations. Thus under this program the recovery of still buried NRX reactor fuel rods and their relocation to modern fuel storage was identified as a priority. A suspect inventory of NRX fuels was compiled from historical records and various research activities. Site characterization in 2005 verified the physical location of the fuel rods and determined the wooden boxes they were buried in had degraded such that the fuel rods were in direct contact with the soil. The fuel rods were recovered and transferred to a modern fuel storage facility in 2007. Recovered identification tags and measured radiation fields were used to identify the inventory of these fuels. During the retrieval activity, a discrepancy was discovered between the anticipated number of fuel rods and the number found during the retrieval. A total of 32 fuel rods and cans of cut end pieces were recovered from the specified site, which was greater than the anticipated 19 fuel rods and cans. This discovery delayed the completion of the project, increased the associated costs, and required more than anticipated storage space in the modern fuel storage facility. A number of lessons learned were identified following completion of this project, the most significant of which was the potential for discrepancies within the historical records. Historical discrepancies are more likely to be resolved by comprehensive historical record searches and site characterizations. It was also recommended that a complete review of the wastes generated, and the total affected lands as a result of this historic 1952 NRX accident be undertaken. These lessons and recommendations have lead to changes in how the NLLP is executed in the CRL waste management areas. (authors)

  8. Trace fossils of a cyclic chalk-marl succession; the upper Maastrichtian Rørdal Member, Denmark

    DEFF Research Database (Denmark)

    Lauridsen, Bodil Wesenberg; Surlyk, Finn; Bromley, Richard Granville

    2011-01-01

    Trace fossils from an upper Maastrichtian cyclic chalk–marl succession, the Rørdal Member, exposed in the Rørdal quarry, Denmark, are analysed in order to test whether the changes in substrate lithology exerted any control over the ichnodiversity, tiering complexity, and density of the infauna. The...

  9. Report on interlaboratory comparisons of 14C measurements organized by the environmental research branch, Chalk River Laboratories

    International Nuclear Information System (INIS)

    The need for increased quality assurance for measurements performed by the monitoring laboratories at nuclear stations has spurred the introduction of a number of laboratory intercomparisons. This report provides details of two intercomparisons of 14C measurements, including the preparation of potential secondary reference materials, the range of analytical techniques in use at the participating laboratories, and a statistical analysis of the results reported. The agreement evident in the two sets of materials - milk and vegetation - was good. (author)

  10. How Primary and Secondary School Systems Are Dealing with the Internet Paradox: Educational Value vs. Liability Preservation. Chalk Talk.

    Science.gov (United States)

    Journal of Law and Education, 1996

    1996-01-01

    Educators today see the vast network of online information resources known as the Internet as the key to a lifetime of educational learning and development. Discusses pornography, obscenity, defamation, and intellectual property issues, especially the uploading and downloading of information. Concludes with the Shelby County (Kentucky) Schools…

  11. Dose-effects relationships in wild populations of the aquatic snail Campeloma decisum at Chalk River Laboratories

    International Nuclear Information System (INIS)

    In the last decade regulatory bodies worldwide have implemented standards to protect populations of non-human biota (NHB) from the consequences of radiation exposure. This is a departure from previous regulatory frameworks, which were concerned only with protecting man. The implementation of these new standards initiated an ongoing discussion concerning appropriate dose-rate limits for NHB. For the most part, the data utilized for estimating appropriately protective dose-rate limits has come from data collected via the irradiation of NHB in a laboratory setting. While some dose-effects studies have been performed under field conditions, such experiments represent a minority of the available data. This deficit in the literature has resulted in challenges to the established paradigm, with researchers reporting increased radiosensitivity in NHB under field conditions. However, many such studies overlook critical components of dose-effects analysis: lacking either robust ecological technique or dosimetric rigor. The study cited herein provides rigorous analysis of factors affecting populations of aquatic snails and is intended as a framework for identifying those factors statistically indicative of snail population. These benchmarks (e.g., number of snails, mass of individuals) were employed as proxies for snail population health, and how it was impacted by over two dozen environmental variables. Dose-rates were calculated via a novel voxel model, developed for this study to estimate internal dose rates for the species of interest. A linear regression model was employed to tease out the relationship between individual snails, their environment, and radiation dose rate. There was no evidence that snail population health was influenced by radiation exposure (p=0.70) at the observed dose rates. Of the environmental variables tested, water concentration of Ca was well correlated with snail mass size (p<0.001), while water concentration of P was well correlated with the number of snails lured to a trap (p<0.001). The protocols and procedures developed as a part of this study represent novel, robust techniques for evaluating the relationship between radiation dose and population effects in NHB. Oregon State University would like to gratefully acknowledge funding from Atomic Energy of Canada Limited for this project. Document available in abstract form only. (authors)

  12. Infrared spectroscopy and density functional theory investigation of calcite, chalk, and coccoliths-do we observe the mineral surface?

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Hem, Caroline Piper; Schultz, Logan Nicholas;

    2014-01-01

    broadening from macroscopic dielectric effects. We detect water adsorbed on the high surface area synthetic calcite, which permits observation of the chemistry of thin liquid films on calcite using transmission infrared spectroscopy. The combination of infrared spectroscopy and density functional theory also...... asymmetric for the coccoliths and the synthetic calcite prepared using the carbonation method. It can be very well fitted by two peaks: a narrow Lorenzian at lower frequency and a broader Gaussian at higher frequency. These two samples both have a high specific surface area. Density functional theory for...

  13. Measured and computed solute transport behaviour in the saturated zone of a fractured and slightly karstified chalk aquifer

    OpenAIRE

    Dassargues, Alain; Goderniaux, Pascal; Daoudi, Moubarak; Orban, Philippe

    2011-01-01

    Solute transport in the saturated zone of a micro-fissured, fractured and even locally slightly karstified aquifer has been studied by multi-tracer tests in groundwater convergent flow conditions to pumping wells or towards a collecting gallery. Different behaviour has been detected that can be described by three kinds of typical breakthrough curves: (a) transport with a dominant advective component, producing narrow and symmetrical observed breakthrough curves, characteristic of solute trans...

  14. PCI fuel failure analysis: a report on a cooperative program undertaken by Pacific Northwest Laboratory and Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    Reactor fuel failure data sets in the form of initial power (P/sub i/), final power (P/sub f/), transient increase in power (ΔP), and burnup (Bu) were obtained for pressurized heavy water reactors (PHWRs), boiling water reactors (BWRs), and pressurized water reactors (PWRs). These data sets were evaluated and used as the basis for developing two predictive fuel failure models, a graphical concept called the PCI-OGRAM, and a nonlinear regression based model called PROFIT. The PCI-OGRAM is an extension of the FUELOGRAM developed by AECL. It is based on a critical threshold concept for stress dependent stress corrosion cracking. The PROFIT model, developed at Pacific Northwest Laboratory, is the result of applying standard statistical regression methods to the available PCI fuel failure data and an analysis of the environmental and strain rate dependent stress-strain properties of the Zircaloy cladding

  15. From Chalk and Talk to Walking the Walk: Facilitating Dynamic Learning Contexts for Entrepreneurship Students in Fast-Tracking Innovations

    Science.gov (United States)

    Gilbert, David H.

    2012-01-01

    Purpose: The purpose of this paper is to examine the notion of designing and developing applied, industry-engaged learning environments that embrace ambiguity and uncertainty in overcoming pedagogical inertia in educating young entrepreneurs and innovators. The research reported on proposes a solution to the dual expectations of producing…

  16. "A Chrome Yellow Blackboard with Blue Chalk": New Education and the New Architecture--Modernism at Koornong School

    Science.gov (United States)

    Goad, Philip

    2010-01-01

    This paper examines, through one school's location in Australia, the international reach and nature of the networks associated with New Education; the aims and ideals of Clive and Janet Nield, the main protagonists behind the venture of Koornong School; what transformations they brought to progressive education; and the deliberate assembling of a…

  17. Teaching without a Blackboard and Chalk: Conflicting Attitudes towards Using ICTs in Higher Education Teaching and Learning

    Science.gov (United States)

    Tummons, Jonathan; Fournier, Cathy; Kits, Olga; MacLeod, Anna

    2016-01-01

    This article, derived from a three-year ethnography of distributed medical education provision in a Canadian university, explores the ways in which information and communication technologies are used by teachers and students in their everyday work within technologically rich teaching environments. The environments being researched are two…

  18. Differential early diagenetic low-Mg calcite cementation and rhythmic hardground development in Campanian-Maastrichtian chalk

    DEFF Research Database (Denmark)

    Molenaar, Nicolaas; J.J.P., Zijlstra

    1997-01-01

    and differences in the degree of early diagenesis. Cemented layers and hardgrounds are the result of differential early marine calcite cementation. In these limestones early calcite cementation cannot be explained by the supply of cementing materials from saturated seawater, An alternative model for...... early marine calcite cementation is proposed, in which early calcite cementation occurred within the sediment at some distance below the seafloor as a result of organic matter degradation and internal redistribution of bioclastic carbonate. Bacterial organic matter degradation caused dissolution of...... relatively unstable high-Mg calcite (and/or aragonite) in the oxic zone followed by precipitation of calcite cement as a consequence of bacterial iron reduction. During periods with a lower sedimentation rate, any significant early cementation and replacement of high-Mg calcite occurred when younger oxic...

  19. Summary record of the twenty-third meeting, (technical sessions), Chalk River, Canada, 27 Sep - 1 Oct 1982

    International Nuclear Information System (INIS)

    The technical sessions deal with advances in nuclear data measurements and newer facilities (with special attention paid to data for fission and fusion reactors); advances in nuclear data evaluations (regional activities and joint evaluated file); activities of nuclear data centres; report on recent NEA meetings; subcommittee reports

  20. Proceedings of the Fetal Dosimetry Workshop held in Chalk River, ON (Canada), 25-26 June 1991

    International Nuclear Information System (INIS)

    It is important to ensure adequate protection of the developing embryo or fetus in situations where the parent, usually the mother, is potentially exposed to radionuclides. An embryo or fetus can be exposed to ionizing radiation by external or internal sources. The dose from external sources can be assessed relatively easily. There is considerable uncertainty as to what the fetal doses are following maternal intakes, and whether low doses of radiation to the fetus cause childhood cancer. This workshop was held to help address these issues. Discussions centered in particular on the biokinetics of the distribution and retention of radionuclides in the fetus and newborn, effects of incorporated radionuclides in the embryo or fetus, metabolic and dosimetric models, and radioprotection considerations. Eleven papers were presented

  1. Microarthropods inventory in a range of forests

    NARCIS (Netherlands)

    Jagers Op Akkerhuis, G.A.J.M.; Dimmers, W.J.

    2014-01-01

    May-June 2005, inventory of microarthropod fauna on experimental plots in 20 forests divided over The Netherlands using a split-tube-sampler. Treatments are chalk-no chalk and fertilizer-no fertilizer

  2. Fractures and Rock Mechanics, Phase 1

    DEFF Research Database (Denmark)

    Havmøller, Ole; Krogsbøll, Anette

    1997-01-01

    The main objectives of the project are to combine geological description of fractures, chalk types and rock mechanical properties, and to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. Five chalk types, representing two outcrop localities: Stevns and...

  3. Electric dewatering and drying of fine-grained products; Elektrisk afvanding og toerring af finkornede produkter

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, H.K.; Villumsen, A.

    2001-07-01

    The aim of the project was to elucidate four aspects related to using electric direct current to find an energy saving alternative to existing methods within dewatering of fine-grained products. The four aspects were a) electrophoresis forced sedimentation of chalk slurry, b) electro osmotic dewatering of chalk slurry, c) electro osmotic dewatering of agricultural chalk and d) electro osmotic dewatering of liquid organic wastes. (EHS)

  4. Geohydrologic-engineering geology evaluation of the Selma Group in western Alabama and northeast Mississippi for possible radioactive waste disposal

    International Nuclear Information System (INIS)

    The following topics are discussed: regional stratigraphy, lithologic characteristic-chalk sequences, structural geology settting, earthquakes and historical seismicity, regional geomorphology, recovery of geological resources, and groundwater hydrology

  5. Particle diffusion in complex nanoscale pore networks

    DEFF Research Database (Denmark)

    Müter, Dirk; Sørensen, Henning Osholm; Bock, H.;

    2015-01-01

    We studied the diffusion of particles in the highly irregular pore networks of chalk, a very fine-grained rock, by combining three-dimensional X-ray imaging and dissipative particle dynamics (DPD) simulations. X-ray imaging data were collected at 25 nm voxel dimension for two chalk samples...

  6. Decomposition and reduction of N2O over Limestone under FBC Conditions

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Jensen, Anker; Vaaben, Rikke;

    1997-01-01

    The addition of limestone for sulfur retention in FBC has in many cases been observed to influence the emission of N2O. The catalytic activity of N2O over calcined Stevns Chalk for decomposition of N2O in a laboratory fixed bed quartz reactor was measured. It was found that calcined Stevns Chalk ...

  7. Eelgrass fairy rings: sulfide as inhibiting agent

    DEFF Research Database (Denmark)

    Borum, Jens; Raun, Ane-Marie Løvendahl; Hasler-Sheetal, Harald; Pedersen, Mia Østergaard; Pedersen, Ole; Holmer, Marianne

    2014-01-01

    Distinct ‘fairy rings’ consisting of narrow fringes of eelgrass (Zostera marina l.) expand radially over a bottom of chalk plates outside the calcium carbon- ate cliffs of the island of Møn, Denmark. We conducted a survey to evaluate possible explanations for the formation of the rings and, more...... expanded over the bare chalk plates. On the inner side, shoots were smaller, had lower absolute and specific leaf growth, shoot density was lower and the sediment eroded leaving the bare chalk with scattered boulders behind. Sediment organic matter and nutrients and tissue nutrient contents were not...

  8. Smaller Calcite Lattice Deformation Caused by Occluded Organic Material in Coccoliths than in Mollusk Shell

    DEFF Research Database (Denmark)

    Froelich, Simon; Sørensen, H.O.; Hakim, S.S.;

    2015-01-01

    The growth and nucleation of biominerals are directed and affected by associated biological molecules. In this paper, we investigate the influence of occluded biomolecules on biogenic calcite from the coccolithophorid Pleurochrysis carterae and from chalk, a rock composed predominantly of fossil...... suggests that the interaction between biomolecules and calcite is not as tight in the coccoliths as in the shell. Although the shape of chalk has been preserved over millions of years, no major influence on the crystal lattice was observed in the chalk samples....

  9. Wastewater filtration and re-use: An alternative water source for London

    International Nuclear Information System (INIS)

    The rapid growth and climate of the Greater London region have contributed towards large deficits in water supply. Inexpensive, energy-efficient and sustainable water resource schemes are increasingly sought as a means to boost supply. Here, we propose a small-scale recycling scheme whereby tertiary-treated wastewater is pumped to the Cretaceous chalk of the London Basin. By taking advantage of the natural filtration properties of the underlying chalk, contaminants can be effectively attenuated over relatively short length scales to result in pure water. The problem is approached from four different scales. First, we define two localities in London where such a pumping scheme might operate; regions which combine a thick unsaturated zone and high chalk transmissivity, both essential to ensure maximum contaminant removal and minimum environmental impact. Secondly, the effects of pumping fluid into the Chalk at the two localities are quantified using a finite-difference groundwater flow model. We show that rivers impose a regular groundwater flow regime, whereas pre-existing abstraction wells will lead to less predictable results. Thirdly, we consider the effect of fractures on channelling rapid fluid flow within the rock mass. By digitising a fracture map based upon outcrop measurements from chalk exposed on the Kent coast similar to that beneath London, we quantify transport patterns of wastewater after injection. Imbibition to the chalk matrix (and therefore filtration) will occur where fluid pressure gradients are highest, for instance around disconnected fracture tips. Finally we demonstrate the efficacy of chalk in contaminant removal by injecting an analogue ‘effluent’ through a chalk core. ICP-AES analysis on the recovered solution shows the contaminants (viz. a suite of heavy metals) are arrested or removed over relatively small time- and length-scales. Numerical and analytical solutions fit the data poorly, shedding some light on the importance of

  10. An accident involving transport of radioactive materials, Canada 1994 March

    International Nuclear Information System (INIS)

    AECL-Chalk River Laboratories (CRL) located at Chalk River, Ontario, routinely ships radioisotopes in bulk to Nordion International Inc. in Kanata, Ontario. On 1994 March 22, an AECL vehicle carrying three packages containing radioisotopes collided with a tractor trailer carrying steel, approximately 15 km east of the Chalk River Laboratories. The AECL-CRL emergency response plan was activated. A series of post-accident meetings were held to evaluate the effectiveness of the plan and to address any identified deficiencies. AECL-CRL is continuing to work towards addressing the identified deficiencies. (author). 2 figs

  11. Um bocado de sexo, pouco giz, quase nada de apagador e muitas provas: cenas escolares envolvendo questões de gênero e sexualidade A lot of sex, a little chalk, almost no eraser and many tests: school scenes involving gender and sexuality

    OpenAIRE

    Fernando Seffner

    2011-01-01

    O texto está centrado no relato e na análise de cenas escolares, fruto de etnografia em salas de aula do ensino fundamental e do ensino médio na cidade de Porto Alegre, onde questões de gênero e sexualidade estão implicadas. O roteiro de cenas selecionadas permite transitar entre temas que envolvem autonomia pedagógica da escola; aprendizagem científica e processos de socialização no ambiente escolar; educação pública laica; valorização da diversidade; estratégias de inclusão; políticas de eq...

  12. Um bocado de sexo, pouco giz, quase nada de apagador e muitas provas: cenas escolares envolvendo questões de gênero e sexualidade A lot of sex, a little chalk, almost no eraser and many tests: school scenes involving gender and sexuality

    Directory of Open Access Journals (Sweden)

    Fernando Seffner

    2011-08-01

    Full Text Available O texto está centrado no relato e na análise de cenas escolares, fruto de etnografia em salas de aula do ensino fundamental e do ensino médio na cidade de Porto Alegre, onde questões de gênero e sexualidade estão implicadas. O roteiro de cenas selecionadas permite transitar entre temas que envolvem autonomia pedagógica da escola; aprendizagem científica e processos de socialização no ambiente escolar; educação pública laica; valorização da diversidade; estratégias de inclusão; políticas de equidade de gênero; qualidade das aprendizagens escolares; papel do professor como um adulto de referência; e especificidades da educação pública. Privilegiam-se atravessamentos de gênero e sexualidade com raça, classe social, pertencimento religioso, moralidades familiares e geração. Ao final, estabelecemos alguns princípios gerais para o trabalho com gênero e sexualidade na escola.The text focuses on reporting and analyzing school scenes, as a result of ethnography in elementary and middle school classrooms in Porto Alegre, Brazil. In these scenes questions of gender and sexuality are involved. The scenes selected deal with issues involving the school's educational autonomy; scientific learning and socialization processes in the school environment; secular public education; appreciation of diversity; inclusion strategies; policies of gender equity; quality of school learning; role of the teacher as an adult reference; specificities of public education. Preference is given to intersections of gender and sexuality with race, social class, religion, morals and family generation. In the end, we establish some general principles for working with gender and sexuality in school.

  13. Acid Raindrops Keep Fallin' in My Lake.

    Science.gov (United States)

    Journal of Chemical Education, 2003

    2003-01-01

    Demonstrates acid rain falling into lakes using vinegar and explores the effects on different types of solids such as chalk, sand, and lime. Includes instructor information and student worksheets. (YDS)

  14. Progress report: Physical Sciences - TASCC Division, 1992 July 01 -December 31

    International Nuclear Information System (INIS)

    This report summarizes operations and research activities in the Nuclear Physics Branch and the TASCC Accelerators and Development Branch at Chalk River Laboratories during the last half of 1992. 27 figs., 10 tabs

  15. Geohydrologic-engineering geology evaluation of the Selma Group in western Alabama and northeast Mississippi for possible radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, S.

    1975-06-01

    The following topics are discussed: regional stratigraphy, lithologic characteristic-chalk sequences, structural geology settting, earthquakes and historical seismicity, regional geomorphology, recovery of geological resources, and groundwater hydrology. (LK)

  16. Progress report: Physical Sciences - Physics Division, 1992 July 01 -December 31

    International Nuclear Information System (INIS)

    This report summarizes operations and research activities in the Accelerator Physics, Neutron and Condensed Matter Science and Theoretical Physics branches at Chalk River Laboratories during the last half of 1992. 21 figs., 3 tabs

  17. Channelling versus inversion

    DEFF Research Database (Denmark)

    Gale, A.S.; Surlyk, Finn; Anderskouv, Kresten

    2013-01-01

    . Within this channel were smaller erosional structures (<10 m deep) that truncate originally horizontal bedding, are floored by hardgrounds, and locally have a basal fill of granular phosphorite. The entire channel system was progressively infilled by chalk, as demonstrated by the expanded succession of...... the lower Campanian Culver Chalk Formation. The beds of the channel fill are cut by small step faults, resulting from gravitational collapse. Complete burial had taken place by the base of the upper Campanian Portsdown Chalk Formation, which is of even thickness across the region. The structures are......Evidence from regional stratigraphical patterns in Santonian−Campanian chalk is used to infer the presence of a very broad channel system (5 km across) with a depth of at least 50 m, running NNW−SSE across the eastern Isle of Wight; only the western part of the channel wall and fill is exposed...

  18. TASCC newsletter volume 5 no. 5

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this May issue is information on a workshop for material science studies, a facility report and operating record and the experiments conducted. 1 fig

  19. Rõõm muusikast / Mati Märtin

    Index Scriptorium Estoniae

    Märtin, Mati

    2005-01-01

    Ülestõusmispühade-kontsertidest Tallinna kirikutes: Päästearmee Londoni puhkpilliorkestri Chalk Farm Band kontserdist Kaarli kirikus, Eesti Muusikaakadeemia õpilaste kontserdist Jaani kirikus, Leedsi Filharmoonia Segakoori kontserdist Kaarli kirikus

  20. TASCC newsletter volume 6 no. 6

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this June issue is a report on operator training, operating record and facility report and a listing of experiments conducted in June

  1. TASCC newsletter volume 9 no. 4

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this April issue of TASCC is an update of the facility, analysis of Chernobyl samples, staff changes, Internet availability and a listing of April's experiments. 1 fig

  2. Пираты третьего тысячелетия / коммент. Питер Чалк, Гордан Ван Хук

    Index Scriptorium Estoniae

    2009-01-01

    Piraatlusest Somaalia piirkonnas ja rahvusvahelistest alusdokumentidest piraatluse vastu võitlemiseks 21. sajandil. Kommenteerivad uurimiskeskuse RAND Corporation vanempoliitanalüütik Peter Chalk ja transpordikompanii Maersk Line innovatsiooni ja arenduse vanemdirektor Gordan Van Hook

  3. Fractures and Rock Mechanics, Phase 1

    DEFF Research Database (Denmark)

    Krogsbøll, Anette; Jakobsen, Finn; Madsen, Lena

    1997-01-01

    The main objective of the project is to combine geological descriptions of fractures, chalk types and rock mechanical properties in order to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. This report deals with 1) geological descriptions of outcrop locality ...... Hillerslev quarry, 2) Classification and description of all samples (normal and large scale) and 3) Evaluation of stress- and deformation history....

  4. Experience in handling concentrated tritium

    International Nuclear Information System (INIS)

    The notes describe the experience in handling concentrated tritium in the hydrogen form accumulated in the Chalk River Nuclear Laboratories Tritium Laboratory. The techniques of box operation, pumping systems, hydriding and dehydriding operations, and analysis of tritium are discussed. Information on the Chalk River Tritium Extraction Plant is included as a collection of reprints of papers presented at the Dayton Meeting on Tritium Technology, 1985 April 30 - May 2

  5. Comments on nuclear reactor safety in Ontario

    International Nuclear Information System (INIS)

    The Chalk River Technicians and Technologists Union representing 500 technical employees at the Chalk River Nuclear Laboratories of AECL submit comments on nuclear reactor safety to the Ontario Nuclear Safety Review. Issues identified by the Review Commissioner are addressed from the perspective of both a labour organization and experience in the nuclear R and D field. In general, Local 1568 believes Ontario's CANDU nuclear reactors are not only safe but also essential to the continued economic prosperity of the province

  6. In situ Observation of Nucleated Polymer Crystallization in Polyoxymethylene Sandwich Composites

    OpenAIRE

    Slouf, Miroslav; Krejcikova, Sabina; Vackova, Tatana; Kratochvil, Jaroslav; Novak, Libor

    2015-01-01

    We introduce a dynamic sandwich method, which can be used for in situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM) composites with three nucleating agents: talc micropowder (POM/mTalc), chalk nanopowder (POM/nChalk), and titanate nanotubes (POM/TiNT). The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtom...

  7. In-situ observation of nucleated polymer crystallization in polyoxymethylene sandwich composites

    OpenAIRE

    Miroslav eSlouf; Sabina eKrejcikova; Tatana eVackova; Jaroslav eKratochvil; Libor eNovak

    2015-01-01

    We introduce a dynamic sandwich method, which can be used for in-situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM) composites with three nucleating agents: talc micropowder (POM/mTalc), chalk nanopowder (POM/nChalk) and titanate nanotubes (POM/TiNT). The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtome...

  8. LABORATORY INVESTIGATIONS OF SILICATE MUD CONTAMINATION WITH CALCIUM

    OpenAIRE

    Nediljka Gaurina-Međimurec; Katarina Simon; Davorin Matanović

    2004-01-01

    The silicate-based drilling fluid is a low solids KCl/polymer system with the addition of soluble sodium or potassium silicate to enhance inhibition and wellbore stability. Silicate-based drilling fluids exhibit remarkable shale and chalk stabilizing properties, resulting in gauge hole and the formation of firm cuttings when drilling reactive shales and soft chalks. Silicates protect shales by in-situ gellation when exposed to the neutral pore fluid and precipitation, which occurs on contact ...

  9. Clay cortex in epikarst forms as an indicator of age and morphogenesis-case studies from Lublin-Volhynia chalkland (East Poland, West Ukraine)

    Science.gov (United States)

    Dobrowolski, Radosław; Mroczek, Przemysław

    2015-10-01

    Clay cortex from the contact zone between the host rock (chalk) and infilling deposits were examined in paleokarst forms (pockets, pipes, and dolines of different age) from the Lublin-Volhynia chalk karst region. In light of the sedimentological and micromorphological analyses, it seems possible to work out a model as the basis for genetic and stratigraphic discussions. (1) Dolines with the Paleogene or Neogene mineral infills are characterized by (a) homogeneous, residual type of massive clay gradually passing into the chalk monolith, and at the same time (b) relatively thick weathered zone. (2) Pipes with glacigenic mineral infill from the Saalian Glacial are characterized by (a) sharp contact between host rock and clay, (b) narrow weathering zone of chalk, (c) diffuse nature of the contact zone between residual clay and mineral infill, and (d) contamination of clay by clastic material. (3) Pockets with glacigenic mineral infill and traces of the Weichselian periglacial transformation are characterized by (a) strong contamination of chalk by quartz grains, (b) diffuse transition between clay and infill: from clayey matrix with single quartz grains (at the contact with chalk) to clayey coatings and intergranular bridges (in the infill), (c) intensive weathering (cracking) of mineral grains in the infill.

  10. POWERPOINT PRESENTATION VS BLACKBOARD TEACHING: A COMPARATIVE STUDY AND EVALUATION IN GOVERNMENT MEDICAL COLLEGE, ANANTHAPURAMU, ANDHRA PRADESH FOR II M.B.B.S STUDENTS: A QUESTIONNAIRE BASED STUDY

    Directory of Open Access Journals (Sweden)

    Ramachandrudu

    2016-03-01

    Full Text Available Chalk talk lecture is the oldest and most commonly used teaching technique. However, it is also common to use PowerPoint presentations after the introduction of digitalized teaching in medical colleges. This study is done to compare effectiveness of PowerPoint lecture with Conventional chalk talk lecture. AIM This study is designed to determine effectiveness of Chalk Talk Teaching vs. PowerPoint Teaching in medical education. METHODS This study was done on three successive batches of II M.B.B.S students from the year August 2013–December 2015 (Total 300 students in Government Medical College, Ananthapuramu, Andhra Pradesh, after getting approved by Institutional Ethical committee and informed consent from the students. During regular Pharmacology Lectures, the students were divided into 2 classes. One class (150 had a chalk talk lecture, while the other class (150 had PowerPoint lecture. At the end of each lecture, a questionnaire (Containing 10 open ended Questions is given to all the students of the class. STATISTICS Descriptive statistics was used to analyse data and results were expressed in terms of percentage. RESULTS Students of both the groups answered questions related to memory and calculations well. However, the students of PowerPoint group answered in a better way to questions related to “Understanding and memorizing.” In this study, 85% of the students preferred PowerPoint and only 15% preferred conventional chalk talk.

  11. Influence of pH and Oxidant Ozone to Amount of Bacterium Coliform at Hospital Waste

    International Nuclear Information System (INIS)

    Influence of pH and oxidant ozone to amount of bacterium coliform at hospital waste have been done. As sample is liquid waste Public Hospital of town (RSUD) Yogyakarta. Sample waste processed by 3 kinds of treatment, that is first certain ozone waste during, that is waste given by the third and just chalk of waste given by the certain and ozonization chalk during. From third the treatment, in the reality third treatment which can give the maximal result, that is waste given the chalk until pH waste 8.5 and ozonization during 40 minute give the following result : bacterium coliform from 810.000 MPN become 0 MPN ( cell / 100 mL). This result have fulfilled the conditions as according to decision of Governor of DIY no. 65 year 1999 for the waste of faction II, that is waste used for the irrigation of fishery and agriculture. (author)

  12. Dynamic rock fragmentation: thresholds for long runout rock avalanches

    Directory of Open Access Journals (Sweden)

    E.T. Bowman

    2014-10-01

    Full Text Available The dynamic fragmentation of rock within rock avalanches is examined using the fragmentation concepts introduced by Grady and co-workers. The analyses use typical material values for weak chalk and limestone in order to determine theoretical strain rate thresholds for dynamic fragmentation and resulting fragment sizes. These are found to compare favourably with data obtained from field observations of long runout rock avalanches and chalk cliff collapses in spite of the simplicity of the approach used. The results provide insight as to the energy requirements to develop long runout behaviour and hence may help to explain the observed similarities between large rock avalanches and much smaller scale chalk cliff collapses as seen in Europe.

  13. Hydrogeology of Mors

    International Nuclear Information System (INIS)

    The covering layers protect the salt in the dome. Ground water velocities are small and the chalk exhibits good retention properties for the radionuclides. As ground water velocities below 500 m are small, knowledge of hydrogeology over only a small area over the dome is necessary (1 km horizontal transport takes about 15 mill. years). Additionally if the retention properties of the chalk together with radioactive decay are taken into account, it becomes obvious that the nuclides can travel only a few metres into the chalk, before they have decayed to safe radioactive levels. Therefore it does not appear to be necessary to investigate the hydrogeology beyond a few metres from the disposal area. The hydrogeological investigations that have been carried out, although they cover only a limited area, thus give an excellent and sufficient basis for a safety evaluation for determining the suitability of the Mors salt dome for waste disposal. (EG)

  14. Method of analyzing gas sorbed by rock

    Energy Technology Data Exchange (ETDEWEB)

    Nesterenko, L.T.; Denisova S.N.; Mikhal' kov, P.V.

    1981-03-07

    The invention is related to the area of the analysis of gas and can be used in geological prospecting for oil and gas. Its purpose is to increase the accuracy of analysis by increasing the completeness of hydrocarbon extraction from the samples of clays. This is achieved by adding chalk to the aqueous suspension of clay, and the obtained suspension of chalk and clay in water are subjected to reaction with hydrochloric acid, after which NaCl is added to the solution until saturation. This method permits practically all hydrocarbon gas to be displaced from the suspended clay solution.

  15. Brine Distribution after Vacuum Saturation

    DEFF Research Database (Denmark)

    Hedegaard, Kathrine; Andersen, Bertel Lohmann

    1999-01-01

    Experiments with the vacuum saturation method for brine in plugs of chalk showed that a homogeneous distribution of brine cannot be ensured at saturations below 20% volume. Instead of a homogeneous volume distribution the brine becomes concentrated close to the surfaces of the plugs......Experiments with the vacuum saturation method for brine in plugs of chalk showed that a homogeneous distribution of brine cannot be ensured at saturations below 20% volume. Instead of a homogeneous volume distribution the brine becomes concentrated close to the surfaces of the plugs...

  16. Production of Calcareous Nannofossil Ooze for Sedimentological Experiments

    DEFF Research Database (Denmark)

    Buls, Toms; Anderskouv, Kresten; Fabricius, Ida Lykke;

    2015-01-01

    subject. However, the use of modern calcareous nannofossil ooze as an analogue for Cretaceous ooze is associated with a number of disadvantages such as generally higher noncarbonate content and smaller coccolith size of modern oozes. Here, we document a preparation method for the production of calcareous......, laser diffraction granulometry, and smear slides. The Upper Cretaceous chalk chosen for disaggregation is highly friable due to delicate contact cement and has a low noncarbonate content (<2 wt %), a high porosity, friability, and good nannofossil and microfossil preservation. These characteristics...... validating the use of the freeze-thaw method for production of experimental ooze to model the basic depositional behavior of Cretaceous chalk....

  17. Mise en évidence de fortes circulations verticales temporaires entre zones humides et aquifères alluviaux et régionaux

    Science.gov (United States)

    Weng, Philippe; Coudrain-Ribstein, Anne; Kao, Cyril; Bendjoudi, Hocine; Marsily, Ghislain de

    1999-08-01

    Tensiometric and piezometric values were recorded in an alluvial valley of the Seine wetland from February to November 1998. As a consequence of two flood events, the groundwater head once rose above the soil surface. When the water level in the Seine decreased, the vertical hydraulic gradient between the underlying Senonian chalk and the alluvia increased to 16 %o. During the few days of recession the alluvial wetlands were fed by an upward flow from the regional chalk aquifer and drained towards the river through a more permeable alluvial layer (1.5 m to 7 m below soil surface).

  18. The Skælskør structure in eastern Denmark – wrench-related anticline or primary Late Cretaceous sea-floor topography?

    DEFF Research Database (Denmark)

    Surlyk, Finn; Boldreel, Lars Ole; Lykke-Andersen, Holger;

    2010-01-01

    seismic studies of the Chalk Group in Øresund and Kattegat have shown that similar highs actually represent topographic highs on the Late Cretaceous – Danian seafloor formed by strong contourparallel bottom currents. Reflection seismic data collected over the Skælskør structure in order to test the...... Ringkøbing Fyn High into the Danish Basin. The elevated position is maintained due to reduced subsidence as compared with the Danish Basin north of the high. The hypothesis of wrench tectonics as origin can be refuted. The seismic data show that the upper part of the Chalk Group is characterised by irregular...

  19. The use of in-situ deployments to examine the success of water quality mitigation measures on a watercress farm

    OpenAIRE

    Dixon, M J; Shaw, P. J.

    2009-01-01

    Watercress has long been believed to affect macroinvertebrate communities in chalk streams. Harvesting and washing watercress damages plant tissues and releases isothiocyanates which are potential toxicants to Gammarus pulex (L.). This study examined whether impacts on G. pulex of watercress farm factory wash water could be mitigated by treating via recirculation through the watercress beds.

  20. Progress report: Physics Division, 1982 April 1 - June 30

    International Nuclear Information System (INIS)

    Nuclear physics studies that took place at Chalk River Nuclear Laboratories during the second quarter of 1982 are described, as well as work in solid state and theoretical physics. The MP Tandem accelerator was shut down to prepare for the installation of a superconducting cyclotron. Computer codes developed during the period and the operation of the computer facilities are described

  1. Physics case for a multiparticle detector system

    International Nuclear Information System (INIS)

    This report is an examination of the physics which would be accessible to a large multiparticle detector system when used with heavy ion beams of 10 to 50 MeV/u from the Chalk River Tandem Accelerator Superconducting Cyclotron Complex (TASCC)

  2. Dosimetric research at CRNL

    International Nuclear Information System (INIS)

    This paper gives a broad overview of dosimetric research being carried out at Chalk River Nuclear Laboratories. At the time of the report this research group consisted of 8 professionals and approximately 20 support staff. Areas of research discussed are: 1) dosimetry service; 2) dosimeter and monitor development; and 3) dosimetry calculations

  3. Learning through Equity Trading Simulation

    Science.gov (United States)

    Moffit, Timothy; Stull, Charles; McKinney, Hannah

    2010-01-01

    Over the past several decades, colleges and universities have moved away from the traditional chalk-and-talk lecture. Professors have experimented with a myriad of methods to engage students more fully. Some of the innovations that have been used have succeeded in improving student performance and satisfaction. In this paper we report the learning…

  4. Apprentices train for nuclear maintenance

    International Nuclear Information System (INIS)

    A combination of in-plant training, the Ontario provincial apprenticeship training program, and supplementary home study training programs are being combined in an extensive training program for apprentices at Chalk River Nuclear Laboratories. The unusual scope of the laboratory's work and the challenging jobs are valuable in preparing the apprentice for work in nuclear industry. (R.A.)

  5. Palaeoenvironmental changes across the Danian–Selandian boundary in the North Sea Basin

    DEFF Research Database (Denmark)

    Clemmensen, Anne; Thomsen, Erik

    2005-01-01

    southern and eastern part of the North Sea Basin resulted in a huge influx of reworked Cretaceous chalk and an almost complete stop of carbonate production. Finally, later in the early Selandian, in connection to a general sea-level rise and a reduction in the gateway between the North Sea Basin and the...

  6. Nieuwe vondsten van Bryum torquescens (zonneknikmos) in Zuid-Limburg

    OpenAIRE

    Bijlsma, R.J.; During, H. J.

    2005-01-01

    In the Netherlands Bryum torquescens is known mainly from calcareous soils and limestone in the southernmost part of the country. Most records date from the 19th century. The species was rediscovered in chalk grasslands in this same area (1995 and 2002) and in adjacent Belgium (1987).

  7. A Lesson on Evolution & Natural Selection

    Science.gov (United States)

    Curtis, Anthony D.

    2010-01-01

    I describe three activities that allow students to explore the ideas of evolution, natural selection, extinction, mass extinction, and rates of evolutionary change by engaging a simple model using paper, pens, chalk, and a chalkboard. As a culminating activity that supports expository writing in the sciences, the students write an essay on mass…

  8. Bacteria in ice may record climate change

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ To many people, bacteria and climate change are like chalk and cheese: the srnallest creature versus one of the biggest phenomena on Earth. Not really.Scientists with the CAS Institute of Tibetan Plateau Research (ITP) and coworkers recently reported that small bugs deposited in ice and snow might tell how our climate has been changing.

  9. Connecting to the Future

    Science.gov (United States)

    Kennedy, Mike

    2010-01-01

    For the generation of people whose classroom memories consist of chalk squeaking on a blackboard, weather-beaten textbooks and a ready supply of sharpened No. 2 pencils, the resources available to students in many 21st-century American schools may seem unfamiliar, even amazing. Computer networks with access to the Internet--wired or wireless--have…

  10. A review of analytical techniques for the determination of carbon-14 in environmental samples

    International Nuclear Information System (INIS)

    This report contains a brief summary of analytical techniques commonly used for the determination of radiocarbon in a variety of environmental samples. Details of the applicable procedures developed and tested in the Environmental Research Branch at Chalk River Laboratories are appended

  11. Use of GeoGebra in Primary Math Education in Lithuania: An Exploratory Study from Teachers' Perspective

    Science.gov (United States)

    Žilinskiene, Inga; Demirbilek, Muhammet

    2015-01-01

    With the advance of information and communications technologies, new teaching tools are becoming more pervasive. These tools can be utilized in a variety of ways to improve and enhance math teaching. Considering the integration of technology in teaching mathematics, it is clear that the replacement of board and chalk with digital presentation…

  12. Thinking Images: Doing Philosophy in Film and Video

    Science.gov (United States)

    Parkes, Graham

    2009-01-01

    Over the past several decades film and video have been steadily infiltrating the philosophy curriculum at colleges and universities. Traditionally, teachers of philosophy have not made much use of "audiovisual aids" in the classroom beyond the chalk board or overhead projector, with only the more adventurous playing audiotapes, for example, or…

  13. Closing Canada's ‘universal’ reactor

    Science.gov (United States)

    Asghar, M.; Rogge, R.

    2015-08-01

    In reply to a post on the physicsworld.com blog about the forthcoming closure of the National Research Universal reactor at Chalk River, Ontario, Canada (“Lament for ‘the reactor that can do everything’”, 16 June, http://ow.ly/On9VN).

  14. Materials R and D with neutron beams - how the NRU reactor serves Canada further as a unique resource for science and industry

    International Nuclear Information System (INIS)

    This presentation discusses the use of NRU reactor for materials research and development with neutron beams at the Canadian Neutron Beam Centre at the Chalk River Laboratories. The facility has 5 beams for research and development on hard materials, 1 beam for research and development on nano-film and 1 beam for research and development on nano-solution, still under development.

  15. Materials R and D with neutron beams - how the NRU reactor serves Canada further as a unique resource for science and industry

    Energy Technology Data Exchange (ETDEWEB)

    Root, J. [National Research Council Canada, Canadian Neutron Beam Centre, Ottawa, Ontario (Canada)

    2010-07-01

    This presentation discusses the use of NRU reactor for materials research and development with neutron beams at the Canadian Neutron Beam Centre at the Chalk River Laboratories. The facility has 5 beams for research and development on hard materials, 1 beam for research and development on nano-film and 1 beam for research and development on nano-solution, still under development.

  16. 76 FR 12088 - Notice of Intent To Prepare an Environmental Impact Statement for a Proposed Federal Loan...

    Science.gov (United States)

    2011-03-04

    ..., using a High Voltage Direct Current (HVDC) transmission system. The EIS will evaluate the potential... proposed 500 kilovolt (kV) alternating current (AC) transmission line from the existing Chalk Point Substation, in Prince George's County, Maryland, crossing the Patuxent River to a proposed...

  17. TASCC newsletter volume 8 no. 8

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this August issue of TASCC is an update of the facility, personnel changes at TASCC, awards to TASCC personnel, workshop on deflectors, beam calculations on PC's and a listing of August's experiments. 2 figs

  18. Vlasov B. Natural properties of Karst lakes in Belarus / B. Vlasov // Lakes and artificial water reservoirs – functioning, revitalization and protection. – Cosnowiec, 2005. – Р. 249–255.

    OpenAIRE

    Vlasov, Boris

    2005-01-01

    Abstract: Karst lakes of Belarus belong to the azonal type and are distributed in Polesje region in the area of superficial deposition of chalk rocks. Specific features of these type lakes include: small water surface, tunneled form of a hollow, low water exchange rate and increased level of water mineralization; the lakes refer to mesotrophic or eutrophic types.

  19. Mestermærker på flamske 1600-tals tavlemalerier

    DEFF Research Database (Denmark)

    Wadum, Jørgen

    1989-01-01

    , with the aid of a UV lamp, on the backs of panel paintings in the Winter Room, Rosenberg Castle, Copenhagen, as well as in some art galleries and collection in France. The habit of marking with red chalk seems to have been a normal practice at the same time as marking with matrices stamped into the...

  20. Progress report - Physical and Environmental Sciences - TASCC Division -1995 January 1 to June 30

    International Nuclear Information System (INIS)

    Included in this progress report of the TASCC division at Chalk River Nuclear Laboratories is the research and development being carried out at this time and a listing of the relevant publications, reports. lectures and conference contributions. 15 tabs. 19 figs

  1. TASCC newsletter volume 9 no. 7

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this July issue of TASCC is an update of the facility, submission of report by the Program Advisory Committee, government program review begins at AECL, awards to TASCC personnel and a listing of July's experiments. 2 figs

  2. TASCC newsletter Volume 10 no.11/12: final issue

    International Nuclear Information System (INIS)

    A final issue of a newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this final issue is news of TASCC's closure on March 31, 1997, including the dispersement of staff and equipment, also included is a facility report and a listing of experiments conducted in November and December

  3. Adsorption of Carboxylic Acids on Reservoir Minerals from Organic and Aqueous Phase

    DEFF Research Database (Denmark)

    Madsen, Lene; Lind, Ida

    1998-01-01

    Adsorption of organic acids onto North Sea chalk and pure minerals from a hydrocarbon phase and an aqueous phase show that the maximum adsorption is larger for calcite than for silicate surfaces in the hydrocarbon phase. The opposite is observed, however, in the aqueous phase. This suggests that...

  4. TASCC newsletter volume 7 no. 9

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this September issue is an update on the facility report, doppler dispersion, major proposals submitted to NSERC to be situated at TASCC, RCE resonances, beam transport for SNO test, and a listing of September's experiments. 2 figs

  5. Progress report physics division, 1983 July 1 - December 31

    International Nuclear Information System (INIS)

    This report summarizes work carried out during the last half of 1983 in the Physics Division of the Chalk River Nuclear Laboratories in the areas of superconducting cyclotron facility development, nuclear physics research, applied physics, solid state physics, and applied mathematics and computation

  6. De Centauriebremraap (Orobanche elatior Sutton) in Zuid-Limburg: een nieuwe soort voor de Nederlandse flora

    OpenAIRE

    Kreutz, C.A.J.

    1989-01-01

    From 1973 onwards an Orobanche species was found repeatedly (though at intervals of several years) on a chalk slope in the South of Limburg. At first the plant was identified as O. lutea, but the author argues that in fact it is O. elatior. Presumably its host is Centaurea scabiosa.

  7. The olistostroms and cretaceous-Paleocene olistoplakes in sediments of Northern part of Tajik depression

    International Nuclear Information System (INIS)

    In sediments of Northern part of Tajikistan the great amount of massives without foundation and accumulated blocks without order were found. These sediments are from rock of chalk-Palaeogene period. They belong to olistostrom and olistoplaka category. They are found inside neogenic cut

  8. AECL research programs in life sciences

    International Nuclear Information System (INIS)

    The present report summarizes the current research activities in life sciences in the Atomic Energy of Canada Limited-Research Company. The research is carried out at its two main research sites: the Chalk River Nuclear Laboratories and the Whiteshell Nuclear Research Establishment. The summaries cover the following areas of research: radiation biology, medical biophysics, epidemiology, environmental research and dosimetry. (author)

  9. In-situ observation of nucleated polymer crystallization in polyoxymethylene sandwich composites

    Science.gov (United States)

    Slouf, Miroslav; Krejcikova, Sabina; Vackova, Tatana; Kratochvil, Jaroslav; Novak, Libor

    2015-03-01

    We introduce a dynamic sandwich method, which can be used for in-situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM) composites with three nucleating agents: talc micropowder (POM/mTalc), chalk nanopowder (POM/nChalk) and titanate nanotubes (POM/TiNT). The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtomed cross-sections were observed during isothermal crystallization by polarized light microscopy. As the intensity of polarized light was shown to be proportional to the relative crystallinity, the PLM results could be fitted to Avrami equation and the nucleating activity of all investigated particles could be quantified by means of Avrami parameters (n, k). The crystallization half-times increased reproducibly in the following order: POM/nChalk < POM/mTalc < POM/TiNT ~ POM. For strong nucleating agents (mTalc, nChalk), the crystallization kinetics corresponded to spontaneous crystallization starting from central nucleating layer, which was verified by computer simulations. The results were also confirmed by DSC. We concluded that the sandwich method is an efficient microscopic technique for detailed evaluation of nucleating activity of arbitrary micro/nanoparticles in polymer systems.

  10. In-situ observation of nucleated polymer crystallization in polyoxymethylene sandwich composites

    Directory of Open Access Journals (Sweden)

    Miroslav eSlouf

    2015-03-01

    Full Text Available We introduce a dynamic sandwich method, which can be used for in-situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM composites with three nucleating agents: talc micropowder (POM/mTalc, chalk nanopowder (POM/nChalk and titanate nanotubes (POM/TiNT. The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtomed cross-sections were observed during isothermal crystallization by polarized light microscopy. As the intensity of polarized light was shown to be proportional to the relative crystallinity, the PLM results could be fitted to Avrami equation and the nucleating activity of all investigated particles could be quantified by means of Avrami parameters (n, k. The crystallization half-times increased reproducibly in the following order: POM/nChalk < POM/mTalc < POM/TiNT ~ POM. For strong nucleating agents (mTalc, nChalk, the crystallization kinetics corresponded to spontaneous crystallization starting from central nucleating layer, which was verified by computer simulations. The results were also confirmed by DSC. We concluded that the sandwich method is an efficient microscopic technique for detailed evaluation of nucleating activity of arbitrary micro/nanoparticles in polymer systems.

  11. Techniques of Teaching Arabic as a Foreign Language through Constructivist Paradigm: Malaysian Perspective

    Science.gov (United States)

    Faryadi, Qais

    2007-01-01

    This analysis discusses the constructivist paradigm of teaching Arabic as a foreign language in Malaysian settings. This review examines the role of interactive multimedia in enhancing the chalk and talk methods of teaching Arabic in Malaysian schools. This paper also investigates the importance of Arabic Language in Malaysia. Furthermore, the…

  12. An isotope separation magnet for the injector test experiment (MITE)

    International Nuclear Information System (INIS)

    A magnet has been designed for space-charge neutralization studies on the Injector Test Experiment at the Chalk River Nuclear Laboratories. Augmented by suitable collectors, the magnet could also be used for pilot-scale isotope separations. The present report documents the design of this particular magnet and illustrates the process of designing beam transport magnets in general

  13. Pesticide sorption by low organic carbon sediments: A sceening for seven herbicides

    DEFF Research Database (Denmark)

    Madsen, Lene; Lindhardt, Bo; Rosenberg, Per;

    2000-01-01

    The sorption of seven pesticides in 10 Danish aquifer sediments has been studied. These sediments all have a total organic carbon (TOC) content below 1 g kg(-1), and include carbonate-bearing and carbonate-free Quatenary sand deposits and a Cretaceous chalk aquifer. Batch experiments were carried...

  14. TASCC newsletter volume 7 no. 4

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in the April issue is information on damage tests of satellite instrumentation, general news on success of beams achieved, assessment by NPPAP panel on TASCC programs, staff changes and a listing of April's experiments. 2 figs

  15. LABORATORY INVESTIGATIONS OF SILICATE MUD CONTAMINATION WITH CALCIUM

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2004-12-01

    Full Text Available The silicate-based drilling fluid is a low solids KCl/polymer system with the addition of soluble sodium or potassium silicate to enhance inhibition and wellbore stability. Silicate-based drilling fluids exhibit remarkable shale and chalk stabilizing properties, resulting in gauge hole and the formation of firm cuttings when drilling reactive shales and soft chalks. Silicates protect shales by in-situ gellation when exposed to the neutral pore fluid and precipitation, which occurs on contact with divalent ions present at the surface of the shale. Also, silicates prevent the dispersion and washouts when drilling soft chalk by reacting with the Ca2+ ions present on chalk surfaces of cutting and wellbore to form a protective film. The silicate-based drilling fluid can be used during drilling hole section through shale interbeded anhydrite formations because of its superior shale stabilizing characteristics. However, drilling through the anhydrite can decrease the silicate concentration and change rheological and filtration fluid properties. So, the critical concentration of calcium ions should be investigated by lab tests. This paper details the mechanism of shale inhibition using silicate-based drilling fluid, and presents results of lab tests conducted to ascertain the effect of Ca2+ ions on silicate level in the fluid and the fluid properties.

  16. TASCC newsletter volume 7 no. 11

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this November issue of TASCC is an update of the facility, news of a purchase of phase-shifters and a listing of experiments run in November. 2 figs

  17. Powerpoint Presentation in Learning Physiology by Undergraduates with Different Learning Styles

    Science.gov (United States)

    Ankad, Roopa B.; Shashikala, G. V.; Herur, Anita; Manjula, R.; Chinagudi, Surekharani; Patil, Shailaja

    2015-01-01

    PowerPoint presentations (PPTs) have become routine in medical colleges because of their flexible and varied presentation capabilities. Research indicates that students prefer PPTs over the chalk-and-talk method, and there is a lot of debate over advantages and disadvantages of PPTs. However, there is no clear evidence that PPTs improve student…

  18. TASCC newsletter volume 8 no. 9

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this September issue of TASCC is an update of the facility, winner of Nobel prize, dating of fossil seeds using Chlorine 36, promotion of TASCC at a local fair and a listing of September's experiments. 1 fig

  19. Radurisation in commerce

    International Nuclear Information System (INIS)

    Another international achievement was chalked up when South African private enterprise commissioned world's first multipurpose food irradiation plant earlier this year. The development of food irradiation in South Africa from the early days at Pelindaba up to the commissioning of the world's first fully commercial radurisation facility at Tzaneen is briefly traced

  20. Change of MMP dependent on temperature

    DEFF Research Database (Denmark)

    Rudyk, Svetlana Nikolayevna; Søgaard, Erik Gydesen; Akwansa, Eugene

    2008-01-01

       The experiment was conducted with the purpose to investigate how Minimum Miscibility Pressure (MMP) changes at different temperatures. MMP was measured in a high pressure unit. An original oil saturated chalk core plug from the Danish oil field in North Sea was under investigation. The plug...

  1. The Impact of Virtual Reality Programs in Career and Technical Education

    Science.gov (United States)

    Catterson, Anna J.

    2013-01-01

    Instructional technology has evolved from blackboards with chalk to in some cases three-dimensional virtual reality environments in which students are interacting and engaging with other students worldwide. The use of this new instructional methodology, known as "virtual reality," has experienced substantial growth in higher education…

  2. Progress report chemistry and materials division 1984 January 1 - June 30

    International Nuclear Information System (INIS)

    During the first half of 1984 work in the Chemistry and Materials Division of Chalk River Nuclear Laboratories concentrated on studies of ion penetration phenomena, surface phenomena, radiation damage, radiochemical analysis, recycle fuel analysis, gamma spectrometry, mass spectrometry of fuels and moderators, analysis of hydrogen in zirconium alloys, burnup analysis, radiolysis, hydrogen isotope separation, hydrogen adsorption, zirconium corrosion, and metal physics studies of zirconium

  3. Where the sea bed is sinking; Reservoir geology; Der havbunnen synker

    Energy Technology Data Exchange (ETDEWEB)

    Mathiesen, Eric; Njaa, Steinar; Gundersen, Ina

    2007-07-01

    Subsidence of the sea bed was one of the main causes for the evacuation of personnel from Ekofisk and Valhall in the North Sea, the autumn of 2007. A brief presentation of what happens to reservoirs when large amounts of fluids and gases are removed, chalk fields are particularly in focus

  4. Radiation chemistry in the nuclear power reactor environment: from laboratory study to practical application

    International Nuclear Information System (INIS)

    This paper discusses the work carried out at the Chalk River Nuclear Laboratories in underlying and applied radiation chemical research performed to optimise the processes occurring in the four aqueous systems in and around the core. The aqueous systems subject to radiolysis in CANDU reactors are Heat Transport System, Moderator, Liquid Zone Controls and End Shields.

  5. Coincidence of needs in radiological and toxicological protection

    International Nuclear Information System (INIS)

    Research needs for radiological protection and research programs that have evolved to meet these needs parallel closely those in the chemical toxicology field. The similarity of these needs is described as perceived from the radiological side. Further, the frame work for radiologically-related research, out lines of the research programs, and the development of the facilities at Chalk River Nuclear Labs were presented

  6. TASCC newsletter volume 9 no. 8

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this August issue of TASCC is an update of the facility, improvement in memory effects by the AMS at TASCC, personnel news and a listing of August's experiments. 3 figs

  7. TASCC newsletter volume 9 no. 12

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this December issued of TASCC is an update of the facility, a year -end review of TASCC by the director and a listing of December's experiments. 1 fig

  8. Biot's coefficient as an indicator of strength and porosity reduction: Calcareous sediments from Kerguelen Plateau

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Borre, Mai Kirstine; Fabricius, Ida Lykke;

    2010-01-01

    Chalk develops as a result of diagenesis of pelagic calcareous ooze. In a newly deposited ooze sediment, porosity ranges from 60% to 80% but porosity reduces with burial. We studied how different porosity reduction mechanisms change the strength of these deep sea carbonate-rich sediments and effe...

  9. Application of inorganic sorbents for waste waters purification in paper production

    International Nuclear Information System (INIS)

    Present work is devoted to application of inorganic sorbents for waste waters purification in paper production. Therefore as sorbents for waste waters purification of paper production inorganic materials (hydroxides of different elements, bentonite, chalk) are tested. The optimal conditions of sorption are defined.

  10. Energy model in regional energy system

    International Nuclear Information System (INIS)

    In this report is presented a computational model for analysis of energy, materials and mass flux in a complex energy system, at regional scale level. Specifically is described a calculation model of electric power generation for emission forecasting of CO2, SOx, NOx, particulate matter, ashes, limestone, chalks

  11. Total Quality Applied in the Classroom: Students in Virginia Beach Find Early Gains from New Instructional Practices.

    Science.gov (United States)

    Konopnicki, Patrick

    1996-01-01

    After hours of introducing team training, facilitation skills, and Total Quality Management tools, the old classroom practices of "chalk and talk" faded in Virginia Beach schools' technical and career education classes. Academic teachers also improved instruction, using innovative TQM tools such as nominal group voting, course mission statements,…

  12. Using Visualisations in Secondary School Physics Teaching and Learning: Evaluating the Efficacy of an Instructional Program to Facilitate Understanding of Gas and Liquid Pressure Concepts

    Science.gov (United States)

    Oh, Elisabeth Yian Yian; Treagust, David F.; Koh, Thiam Seng; Phang, Wei Lian; Ng, Shuh Lit; Sim, Gary; Chandrasegaran, A. L.

    2012-01-01

    An instructional program using four simulation applets was used to facilitate understanding of gas and liquid pressure concepts among twenty-two students in a Year 9 class from an independent secondary school in Singapore. A comparison group consisting of twenty-two students was taught using traditional didactic, chalk-and-talk instruction.…

  13. Teaching Design in the First Years of a Traditional Mechanical Engineering Degree: Methods, Issues and Future Perspectives

    Science.gov (United States)

    Silva, Arlindo; Fontul, Mihail; Henriques, Elsa

    2015-01-01

    Engineering design is known as an answer to an ill-defined problem. As any answer to an ill-defined problem, it can never be completely right or absolutely wrong. The methods that universities use to teach engineering design, as a consequence of this, suffer from the same fate. However, the accumulated experience with the "chalk and…

  14. E-learning in Type 1 Medical Universities of Iran

    Science.gov (United States)

    Rokni, Mohammad Bagher

    2005-01-01

    Nowadays the Internet is the technological pedestal of organization in the information society and one of the main applications that the Internet offers is the Digital Library (DL). Each society, especially those that claim training of the public, predictably need implementation and endorsement these systems. The time of chalk and board is passed…

  15. TASCC newsletter volume 7 no. 8

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this August issue is information on the status of the TRC's written report, visitors to TASCC, the facility report and new intruder bands that were discovered, as well as a listing of August 's experiments. 2 figs

  16. TASCC newsletter volume 6 no. 7-8

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this summer issue is a report on channeling, news of research talks, personnel changes to TASCC, a facility report and operating record and a listing of July/August experiments

  17. University Students' Conceptions of Bonding in Melting and Dissolving Phenomena

    Science.gov (United States)

    Smith, K. Christopher; Nakhleh, Mary B.

    2011-01-01

    Undergraduate and graduate students' predictions and submicroscopic level explanations for the melting of four materials (salt, chalk, sugar, and butter), and for the mixing of these solutes in two solvents (water and cooking oil) were collected. Twenty-three undergraduate students and seven graduate students participated in the study, and data…

  18. MNR - the beginnings and innovations

    International Nuclear Information System (INIS)

    This paper describes the history of the slowpoke reactor which was built in 1959 at McMaster University. It outlines the history of medical isotope development and production. It produces half the world supply of I-125 used in treatment of prostate cancer and also produced Mo-99 three decades ago during an extended shutdown at Chalk River.

  19. Teaching Economics to the Best Undergraduates: What Are the Problems?

    Science.gov (United States)

    Andreopoulos, Giuliana Campanelli; Panayides, Alexandros

    2009-01-01

    Economics is usually perceived as a difficult subject among undergraduate students with negative repercussions on their performance. The literature suggests that the students' problems with principles of economics are mainly related to the style and method of teaching together with the course content. Particularly attacked are the chalk and talk…

  20. Does Student Quality Matter in the Teaching of Economic Principles?

    Science.gov (United States)

    Andreopoulos, Giuliana Campanelli; Panayides, Alexandros

    2010-01-01

    Economics is usually perceived as a difficult subject among undergraduate students and the literature suggests that the student's problems with principles of economics are mainly related to the chalk and talk type of teaching, the simplicity of economic models, limited discussions on current economic issues, and on race, gender, and other types of…

  1. Spectacular Skies

    Science.gov (United States)

    Nickerson, Jessica

    2008-01-01

    Marbling paper is a favorite in many elementary classrooms. The marbling project described in this article, using a sunset and silhouette concept, is foolproof, inexpensive, and engaging. After looking at images of incredible sunsets for inspiration, each student uses marbling paper, black construction paper, three colors of chalk, and a tub of…

  2. TASCC newsletter volume 8 no. 5

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this May issue of TASCC is an update of the facility, a visit by the Nuclear Physics Technical Review Committee, sizing of meteors, Deep River Science Academy on TASCC projects and a listing of May's experiments. 2 figs

  3. TASCC newsletter volume 9 no. 1

    International Nuclear Information System (INIS)

    A newsletter produced by Chalk River's Tandem Accelerator Superconducting Cyclotron Facility. Included in this January issue of TASCC is an update of the facility, news on distribution of Nuclear Physics News International, installation of the Penning trap mass spectrometer, workshop to be held in June on nuclear physics research, and a listing of January's experiments. 1 fig

  4. Detection of defects in logs using computer assisted tomography (CAT) scanning

    International Nuclear Information System (INIS)

    The Chalk River Nuclear Laboratories of AECL have performed a preliminary feasibility study on the applicability of computer assisted tomographic techniques to detect the internal structure of logs. Cross sections of three logs have been obtained using a medical CAT scanner. The results show that knots, rot and growth rings are easily recognized in both dry and wet logs

  5. Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water

    Science.gov (United States)

    Poston, S. W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  6. Upper Campanian−Maastrichtian holostratigraphy of the eastern Danish Basin

    DEFF Research Database (Denmark)

    Surlyk, Finn; Rasmussen, Susanne Lil; Boussaha, Myriam;

    2013-01-01

    changes in chalk facies, water depths and sea-water temperatures. Combined lithological data, a suite of petrophysical logs including gamma ray (GR) logs, nannofossil and dinoflagellate palaeontology, stable carbon isotopes, seismic reflection and refraction sections form the basis for the definition of...

  7. 76 FR 72405 - Notice of Receipt of Requests to Voluntarily Cancel Certain Pesticide Registrations

    Science.gov (United States)

    2011-11-23

    ... (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only accepted during the Docket....), 2777 S. Crystal Dr., Arlington, VA. The hours of operation of this Docket Facility are from 8:30 a.m...-(Thiocyanomethylthio) benzothiazole Methylene bis (thiocyanate). 065092-00001 ZE LIN Chen Chalk Tralomethrin....

  8. 77 FR 8863 - Product Cancellation Order for Certain Pesticide Registrations

    Science.gov (United States)

    2012-02-15

    ... published for comment in the Federal Register issue of November 23, 2011 (76 FR 72405) (FRL-9327-2). The... Potomac Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. The hours of operation of this Docket...) benzothiazole, Preservative. Methylene bis (thiocyanate). 065092-00001 ZE LIN Chen Chalk Tralomethrin....

  9. Progress report - Physical and Environmental Sciences - TASCC Division -1995 July 1 to December 31

    International Nuclear Information System (INIS)

    Included in this progress report of the TASCC division at Chalk River Nuclear Laboratories is the research and development being carried out at this time and a listing of the relevant publications, reports, lectures and conference contributions. The TASCC staff is also detailed. 8 tabs.,16 figs

  10. Dosimetric Implications of Atmospheric Dispersal of Tritium Near a Heavy-water Research Reactor Facility

    International Nuclear Information System (INIS)

    An estimate of the tritium dose to the public in the vicinity of the heavy water research reactor facility at AECL-Chalk River Laboratories, Ontario, Canada, has largely been accomplished from analyses on regularly-collected samples of air, precipitation, drinking water and foodstuffs (pasture, fruit, vegetables and milk) and environmental dose models. To increase the confidence with which public doses are calculated, tritium doses were estimated directly from the ratio of tritiated species in urine samples from members of the general public. Single cumulative 24 h urine samples from a few adults living in the vicinity of the heavy-water research reactor facility at Chalk River Laboratories, Canada were collected and analysed for tritiated water and organically bound tritium. The participants were from Ottawa (200 km east), Deep River (10 km west) and Chalk River Laboratories. Tritiated water concentrations in urine ranged from 6.5 Bq.l-1 for the Ottawa resident to 15.9 Bq.l-1 for the Deep River resident, and were comparable to the ambient levels of tritium-in-precipitation at their locations. The ultra-low levels of organically bound tritium in urine from these same individuals were measured by 3He-ingrowth mass spectrometry and were 0.06 Bq.l-1 (Ottawa) and 0.29 Bq.l-1 (Deep River). For Chalk River Laboratories workers, tritiated water concentrations in urine ranged from 32 Bq.l-1 to 9.2x104 Bq.l-1, depending on the ambient levels of tritium in their workplace. The organically bound tritium concentrations in urine from the same workers were between 0.08 Bq.l-1 and 350 Bq.l-1. With a model based on the ratio of tritiated water to organically bound tritium in urine, the estimated dose arising from organically bound tritium in the body for the Ottawa and Deep River residents was about 26% and 50%, respectively, of the body water tritium dose. The workers in a reactor building at Chalk River Laboratories has less than 10% dose contribution from organically bound

  11. Accelerated weathering of carbonate rocks following the 2010 forest wildfire on Mt. Carmel, Israel

    Science.gov (United States)

    Shtober-Zisu, Nurit; Tessler, Naama; Tsatskin, Alexander; Greenbaum, Noam

    2015-04-01

    Massive destruction of carbonate rocks occurred on the slopes of Mt. Carmel, during the severe forest fire in 2010. The bedrock surfaces exhibited extensive exfoliation into flakes and spalls covering up to 80%-100% of the exposed rocks; detached boulders were totally fractured or disintegrated. The fire affected six carbonate units -- various types of chalk, limestone, and dolomite. The burned flakes show a consistent tendency towards flatness, in all lithologies, as 85%-95% of the flakes were detached in the form of blades, plates, and slabs. The effects of the fire depend to a large extent on the rocks' physical properties and vary with lithology: the most severe response was found in the chalk formations which are covered by calcrete (Nari crusts). These rocks reacted by extreme exfoliation, at an average depth of 7.7 to 9.6 cm and a maximum depth of 20 cm. The flakes formed in chalk were thicker, longer, and wider than those of limestone or dolomite formations. Moreover, the chalk outcrops were exfoliated in a laminar structure, one above the other, to a depth of 10 cm and more. Their shape also tended to be blockier or rod-like. In contrast, the limestone flakes were the thinnest, with 99% of them shaped like blades and plates. Scorched and blackened faces under the upper layer of spalls provided strong evidence that chalk breakdown took place at an early stage of the fire. The extreme response of the chalks can be explained by the laminar structure of the Nari, which served as planes of weakness for the rock destruction. Three years after the fire, the rocks continue to exfoliate and break down internally. As the harder surface of the Nari was removed, the more brittle underlying chalk is exposed to erosion. If fires can obliterate boulders in a single wildfire event, it follows that wildfires may serve as limiting agents in the geomorphic evolution of slopes. However, it is difficult to estimate the frequency of high-intensity fires in the Carmel region

  12. Short geological description of the Inkai uranium deposit in South Kazakstan

    International Nuclear Information System (INIS)

    The Inkai deposit is located in the territory of the Suzakski region of South Kazakhstan, at 160 km from the railroad station Kzyl-Orda, at the south-western part of Chu-Saryssu uranium ore province. The Chu-Saryssuiskaya depression presents an artesian basin which was formed by water-bearing complexes of upper chalk and of Paleocene-Eocene. During the neotectonic stage of the later Oligocene-Quarternary period, the artesian basin was developed mainly in infiltration regime, this fact led to comprehensive developing of stratum oxidation zones, the boundaries of which are forming regional fronts systems in ore-enclosing complexes horizons. Industrial uranium mineralization is linked with boundaries of stratum oxidation zones in water-bearing horizons (from lower Turonian to middle Eocene ones). The most significant industrial objectives are: in Paleocene sediments -deposits: Uvanas, Kanzhugan, Moinkum; in chalk sediments - Mynkuduk, Zhalpak and the deposit discovered in recent years - Inkai. (author)

  13. Transformation of Heavy Metal Compounds during the Remediation of Contaminated Soils

    Directory of Open Access Journals (Sweden)

    Tatiana Minkina

    2011-03-01

    Full Text Available The effect of ameliorants, chalk, glauconite and semidecomposed cattle manure, on ordinary chernozem contaminated with Zn and Pb was studied in a long-term field experiment. The application of ameliorants significantly decreased the mobility of metals. Their effect depended on the ameliorant and was most significant at the simultaneous application of chalk and manure. This effect was presumably due to the strong binding of metals by carbonates through chemisorption and formation of lowsoluble Zn and Pb compounds and to the additional fixation in the form of complexes at the addition of organic material. The share of loosely bound metal compounds in the contaminated soils decreased to the level typical for the clean soils or even below. The general evolution of the transformation of metal compounds (from less to more firmly bound compounds accelerated by ameliorants remained for both metals.

  14. Ensuring reliable medical isotope supply

    International Nuclear Information System (INIS)

    This paper describes the role of MDS Nordion and AECL in ensuring a reliable global supply of medical isotopes. The First part of the paper discusses the uses of medical isotopes, their importance to the medical community, and the benefits to patients of a secure supply of medical isotopes. The second part describes the role of the NRU reactor and the future role of the MAPLE reactors and New Processing Facility being commissioned at AECL's Chalk River Laboratories for production of medical isotopes to meet the world market demand for the next 40 years. MDS Nordion is the world's leading supplier of medical isotopes. These isotopes are used to conduct some 34,000 nuclear medicine procedures performed every day around the world, such as determining the severity of heart disease, the spread of cancer, and diagnosing brain disorders. These medical isotopes are currently produced primarily by AECL in the NRU reactor at Chalk River, Ontario, Canada. (author)

  15. Modelling of N2O Reduction in a Circulating Fluidized Bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars Erik; Dam-Johansen, Kim;

    1996-01-01

    The addition of limestone for sulphur retention in Fluidized Bed Combustion (FBC) has been observed to influence the emission of N2O, and in many cases a lower emission was observed. The catalytic activity of a Danish limestone (Stevns Chalk) for decomposition of N2O in a laboratory fixed bed...... quartz reactor was measured. It was found that calcined Stevns Chalk is a very active catalyst for N2O decomposition in an inert atmosphere compared to bed material, i.e. a mixture of ash and sand. However, in FBC the limestone is exposed to a mixture of gases, including CO, CO2 and SO2, and sulphation...... uncalcined or recarbonated limestone had negligible activity. Sulphation of the calcined limestone under oxidizing conditions lowered the activity, however sulphidation under reducing conditions showed that CaS is an active catalyst for the reduction of N2O by CO. Without CO present a gas solid reaction...

  16. Decomposition and Reduction of N2O over Limestone under FBC Conditions

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Jensen, Anker; Vaaben, Rikke;

    1997-01-01

    The addition of limestone for sulfur retention in fluidized bed combustion (FBC) has in many cases been observed to influence the emission of N2O. The catalytic activity of N2O over calcined Stevns Chalk for decomposition of N2O in a laboratory fixed bed quartz reactor was measured. It was found...... that calcined Stevns Chalk is an active catalyst for N2O decomposition in an inert atmosphere at FBC temperatures, and the presence of 3 vol% CO increased the rate of N2O destruction by a factor of 5 due to the catalytic reduction of N2O by CO. The activity decreased with increasing CO2 concentration...... reaction between N2O and CaS takes place and SO2 is released....

  17. Automated extraction of faults and porous reservoir bodies. Examples from the Vallhall Field

    Energy Technology Data Exchange (ETDEWEB)

    Barkved, Olav Inge; Whitman, Doug; Kunz, Tim

    1998-12-31

    The Norwegian Vahall field is located 250 km South-West of Stavanger. The production is primarily from the highly porous and fractured chalk, the Tor formation. Fractures, evidently play a significant role in enhancing flow properties as well as production rates, are significantly higher than expected from matrix permeability alone. The fractures are primarily tectonically induced and related to faulting. Syn-depositional faulting is believed to be a controlling factor on reservoir thickness variations observed across the field. Due to the low acoustic contrast and weak appearance of the highly porous chalk, direct evidence of faulting in well bore logs is limited. The seismic data quality in the most central area of the field is very poor due to tertiary gas charging, but in the flank area of the field, the quality is excellent. 1 ref., 5 figs.

  18. Installation and test results of a high-power, CW klystrode amplifier at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    The Chalk River Laboratory (CRL) 1.25 MeV, 267 MHz CW radio frequency quadrupole (RFQ) project has been moved to Los Alamos AOT Division as a collaborative effort between Los Alamos and Chalk River Laboratories. The RF part of this project includes two 267 MHz, 0.25 MW, CW klystrode transmitters. The klystrode is a relatively new type of RF source that combines the input structure from a conventional gridded tube and the output structure of a klystron. It is widely used within the UHF television band at reduced power (60 kW at peak of sync). However, this is the first application of a high power klystrode for a particle accelerator. This paper will describe the experimental configuration at Los Alamos, provide block diagrams of the klystrode transmitter, discuss the attributes of the klystrode which make it a desirable candidate for high efficiency CW accelerators, and present relevant test results

  19. Testing models of basin inversion in the eastern North Sea using exceptionally accurate thermal and maturity data

    DEFF Research Database (Denmark)

    Nielsen, S.B.; Clausen, O.R.; Gallagher, Kerry; Balling, N.

    One difficulty of testing models of basin inversion against data is that erosion has erased the stratigraphic record along the inversion ridge. The depth of erosion therefore cannot be determined. However, thermal maturity data may contain a signal of deeper burial in the past. Here we consider the...... background heat flow, matrix thermal conductivity of sand, shale and chalk, and depositional and erosional episodes during the Cenozoic hiatus. The results show that the data are consistent with none or very limited deposition and erosion during the Cenozoic hiatus after the late Cretaceous compressional...... Cretaceous. A thick (c. 1600 m) late Cretaceous and Danian chalk sequence has recorded the associated marginal trough formation. A hiatus of duration c. 60 Myr follows until the deposition of thin Quaternary sediments. The question we address here is if the thermal data from the wells contain information...

  20. The influence of filler on the properties of elastomeric materials based on poly(ethylene-co-propylene-co-2-ehylidene-5-norbornene rubber

    Directory of Open Access Journals (Sweden)

    Budinski-Simendić Jaroslava

    2006-01-01

    Full Text Available Crosslinked samples based on poly(ethylene-co-propylene-co-2-ehylidene5-norbornene EPDM rubber, carbon black as active filler and natural chalk as inactive filler were cured with sulphur. The content of carbon black was varied from 100 to 200 pph. The content of chalk was varied from 0 to 100 pph. The content of paraffin oil was also varied in some samples. The compounds were prepared by mixing ingredients on a laboratory two-roll mill. Vulcanizates were prepared by curing at 180°C. Various methods were used for the physical and mechanical characterizations. The dynamic mechanical properties of the elastomers were measured in the temperature range from -120 to 80°C.

  1. Shallow, low-permeability reservoirs of northern Great Plains - assessment of their natural gas resources.

    Science.gov (United States)

    Rice, D.D.; Shurr, G.W.

    1980-01-01

    Major resources of natural gas are entrapped in low-permeability, low-pressure reservoirs at depths less than 1200m in the N.Great Plains. This shallow gas is the product of the immature stage of hydrocarbon generation and is referred to as biogenic gas. Prospective low-permeability, gas-bearing reservoirs range in age from late Early to Late Cretaceous. The following facies were identified and mapped: nonmarine rocks, coastal sandstones, shelf sandstones, siltstones, shales, and chalks. The most promising low-permeability reservoirs are developed in the shelf sandstone, siltstone, and chalk facies. Reservoirs within these facies are particularly attractive because they are enveloped by thick sequences of shale which serve as both a source and a seal for the gas.-from Author

  2. The stepwise development of gas production from the Danish North Sea

    International Nuclear Information System (INIS)

    The first hydrocarbon discovery in the entire North Sea was made by the Danish Underground Consortium (DUC) in the Danish sector in 1996 and production was initiated in 1992. Since then, ten fields have been developed in the Danish North Sea by Maersk Olie og Gas AS as operator for DUC and production has reached a level where Denmark has become a net exporter of both oil and gas. So far, all production is from chalk reservoirs. The special properties of low permeability chalk represent a major challenge for field development and production. Technological innovations including horizontal well technology and the simple STAR platform have been key factors in reaching today's production levels. From 1997, annual gas deliveries of some 7.5 x 109 m3 are planned. (au)

  3. A preliminary study of synchrotron light sources for x-ray lithography

    International Nuclear Information System (INIS)

    A preliminary study of synchrotron light sources has been made, primarily oriented toward x-ray lithography. X-ray lithography is being pursued vigorously in several countries, with a goal of manufacturing high-density computer chips (0.25 μm feature sizes), and may attain commercial success in the next decade. Many other applications of soft x-rays appear worthy of investigation as well. The study group visited synchrotron radiation facilities and had discussions with members of the synchrotron radiation community, particularly Canadians. It concluded that accelerator technology for a conventional synchrotron light source appropriate for x-ray lithography is well established and is consistent with skills and experience at Chalk River Nuclear Laboratories. Compact superconducting systems are being developed also. Their technical requirements overlap with capabilities at Chalk River. (32 refs)

  4. Mathematical modelling of fracture hydrology

    International Nuclear Information System (INIS)

    This progress report contains notes on four aspects of hydrological modelling. The first three describe the development of transport models for solute moving with groundwater in fractured rock and the application of the models to field experiments in Cornwall, UK and Chalk River, Canada. The fourth section describes network models which have been used to estimate hydrodynamic dispersion and are in process of being extended to three dimensional systems. (author)

  5. A prototype NDT inspection data bank

    International Nuclear Information System (INIS)

    Existing reliability data banks provide information on items with catastrophic failure modes. However, many system components in a nuclear generating station, e.g., the steam generators, have a time-dependent degradation failure mode. Non-destructive tests associated with this failure mode require a different data base to permit predictive estimates of the component service life and performance. A data base suitable for this failure mode is presently being tested at Chalk River Nuclear Laboratories. (author)

  6. КОАГУЛЯЦИОННАЯ СТРУКТУРА ЦЕМЕНТНОГО ШЛАМА С РАЗНОВИДНОСТЯМИ ГЛИНИСТОГО КОМПОНЕНТА

    OpenAIRE

    Дорогань, Н.

    2013-01-01

    The features of the coagulation structure formation in water dispersed systems – chalk-based cement slurry in the use of clay components with different chemical and mineralogical composition and dispersion are shown. The comparisons of properties of polymineral clay for Portland cement production with the varieties of kaolins, used for white cement production are given. It is noted that varying of the types of clay components in raw mixtures for Portland cement clinker production with the pre...

  7. Fingerprinting groundwater pollution in catchments with contrasting contaminant sources using microorganic compounds

    OpenAIRE

    Stuart, Marianne E.; Lapworth, Dan J.; Thomas, Jenny; Edwards, Laura

    2013-01-01

    Evaluating the occurrence of microorganics helps to understand sources and processes which may be controlling the transport and fate of emerging contaminants (ECs). A study was carried out at the contrasting instrumented environmental observatory sites at Oxford, on the peri-urban floodplain gravel aquifer of the River Thames and Boxford, in the rural valley of the River Lambourn on the chalk aquifer, in Southern England to explore the use of ECs to fingerprint contaminant sources and flow pa...

  8. Hydrogeochemistry of aquifer storage and recovery in the Lower Greensand (London, UK) for seasonal and drought public supply

    OpenAIRE

    Riches, J.; Batey, J.; Jones, M; Butcher, A.S.; Newell, A. J.; Gale, I.N.

    2007-01-01

    Investigations are in progress to determine the potential for ASR, in the Cretaceous Lower Greensand aquifer at Horton Kirby, to meet demand during droughts of up to 2 years, whilst also meeting normal seasonal demands. The sands and sandstones are glauconitic and ferruginous so an understanding of the hydro geochemistry is needed to predict the responses to injection of aerobic water from the overlying Chalk aquifer. Pumped and pore water from the aquifers have been characterised, microcosm ...

  9. Perception and preferences of teaching and learning methods among second year medical students: a cross sectional survey in a rural tertiary care teaching hospital

    Directory of Open Access Journals (Sweden)

    Manu G

    2016-06-01

    Conclusions: Chalk and board teaching remains the best preferred teaching aid which can be supplemented with PPT and OHP to improve medical teaching. Small group discussion is the most preferred learning method when compared with tutorial, student's seminar and lectures indicating that students are more interested in active teaching and learning methods. [Int J Basic Clin Pharmacol 2016; 5(3.000: 1006-1010

  10. Does teaching methods and availability of Teaching resources influence pupils’ Performance: evidence from four Districts in Uganda

    OpenAIRE

    Guloba, Madina; Wokadala, James; Bategeka, Lawrence

    2010-01-01

    This paper explores ways of improving education quality in Universal Primary Education (UPE) schools in Uganda. Following the introduction of UPE in Uganda in 1997, primary school enrolment increased tremendously, leading to a strain on existing teaching resources such as classrooms, teachers’ accommodation, toilets, teachers, chalk, and students’ furniture among others. The inadequacy of teaching resources partly attributes to the low quality of education in UPE schools as reflected in the P...

  11. Rémanence des utilisations anciennes et gestion conservatoire des pelouses calcicoles en France

    Directory of Open Access Journals (Sweden)

    Trivelly E.

    2005-01-01

    Full Text Available Persistence of former land-uses and conservation management of calcareous grasslands in France. In Europe, a lot of chalk grasslands are managed for the conservation of their great biodiversity. However, traditional agricultural practices are at the origin of their existence and maintained them. Although these practices are becoming well documented, very few studies are carried out on the links between traditional agricultural practices and long-term vegetation dynamics. Most of these practices have been abandoned during the last centuries. The aims of our study were to identify the traditional agricultural practices and their impacts on the composition, structure and dynamics of chalk grassland vegetation in interaction with the influence of new management systems created for their biological conservation. Three study sites were chosen in a gradient from North-West France to South-East France. In the chalk grasslands of Upper-Normandy (NW, our results showed that the species which disappeared or are about to disappear from the above-ground vegetation are arable weed species of the 19th century cultivated plots and not typical species of nowadays chalk grasslands. In the centre of France, our results showed that,whatever the present disturbance regimes, old calcareous grasslands always have a higher species richness than grasslands close to former cultivated plots. In South-Eastern France, our results showed that formerly cultivated plots have a very different floristic composition than grazed grasslands. Also, their species-richness is always significantly lower than that of grazed grasslands even after 35 years of abandonment and with the same present disturbance regime. Dry grasslands are not resilient to punctual disturbances taking place within centennial disturbance regimes. Managers must take into account these parameters to set their management priorities. Concurrently to ecological diagnosis and biodiversity inventories, they must carry

  12. Field test of wireless sensor network in the nuclear environment

    International Nuclear Information System (INIS)

    Wireless sensor networks (WSNs) are appealing options for the health monitoring of nuclear power plants due to their low cost and flexibility. Before they can be used in highly regulated nuclear environments, their reliability in the nuclear environment and compatibility with existing devices have to be assessed. In situ electromagnetic interference tests, wireless signal propagation tests, and nuclear radiation hardness tests conducted on candidate WSN systems at AECL Chalk River Labs are presented. The results are favourable to WSN in nuclear applications. (author)

  13. NRX and NRU reactor research facilities and irradiation and examination charges

    International Nuclear Information System (INIS)

    This report details the irradiation and examination charges on the NRX and NRU reactors at the Chalk River Nuclear Labs. It describes the NRX and NRU research facilities available to external users. It describes the various experimental holes and loops available for research. It also outlines the method used to calculate the facilities charges and the procedure for applying to use the facilities as well as the billing procedures.

  14. Isotope shortage triggers delays for patients

    Science.gov (United States)

    Gould, Paula

    2009-07-01

    An unplanned shutdown of a nuclear reactor in Canada is disrupting the supply of medical isotopes across North America and forcing some hospitals to cancel or postpone patients' tests. The closure of the National Research Universal (NRU) reactor in Chalk River, Ontario, has also embarrassed Canadian officials, including a senior government minister who was forced to apologize after calling the isotope shortage a "sexy" career challenge.

  15. A calculational model for the NRU reactor

    International Nuclear Information System (INIS)

    A new computer model to calculate neutronic properties of the NRU research reactor is being implemented at the Chalk River Nuclear Laboratories (CRNL). The model is founded on numerous theoretical studies, on analysis of NRU support experiments done in a zero power reactor, and on comparison with measurements in the NRU reactor. This paper examines the elements of the new calculational model, concentrating on the unique features of NRU and their influences on neutron behaviour

  16. Molybdenum targets for production of 99mTc by a medical cyclotron

    OpenAIRE

    Matei, L.; McRae, G.; Gelbart, W.; Niculae, D.; Craciun, L.; Abeysekera, B.; Johnson, R. R.

    2015-01-01

    Introduction Alternative methods for producing the medical imaging isotope 99mTc are actively being developed around the world in anticipation of the imminent shutdown of the National Research Universal (NRU) reactor in Chalk River, Ontario, Canada and the high flux reactor (HFR) in Petten, Holland that together currently produce up to 80 % of the world’s supply through fission. The most promising alternative methods involve accelerators that focus Bremsstrahlung radiation or protons on me...

  17. NRU turns 50{exclamation_point} World's best research reactor still going strong after a half century

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, F. [Canadian Nuclear Society, Toronto, Ontario (Canada)

    2007-12-15

    This article gives a history of the NRU reactor at Chalk River Nuclear Labs (CRL), Atomic Energy of Canada Ltd. The NRU reactor design was started in 1949 when CRL was Atomic Energy Project of the National Research Council. It was and still is a national facility used by scientists across Canada. As well as providing a source of neutrons for research, it was a home for much of the research required to develop the CANDU reactor design for nuclear power stations.

  18. NRU turns 50! World's best research reactor still going strong after a half century

    International Nuclear Information System (INIS)

    This article gives a history of the NRU reactor at Chalk River Nuclear Labs (CRL), Atomic Energy of Canada Ltd. The NRU reactor design was started in 1949 when CRL was Atomic Energy Project of the National Research Council. It was and still is a national facility used by scientists across Canada. As well as providing a source of neutrons for research, it was a home for much of the research required to develop the CANDU reactor design for nuclear power stations.

  19. A calculational model for the NRU reactor

    International Nuclear Information System (INIS)

    A new computer model to calculate neutronic properties of the NRU research reactor is being implemented at the Chalk River Nuclear Laboratories (CRNL). The model is founded on numerous theoretical studies, on analysis of NRU support experiments done in a zero power reactor, and on comparison with measurement in the NRU reactor. This paper examines the elements of the new calculational model, concentrating on the unique features of NRU and their influences on neutron behaviour

  20. Sympatric speciation revealed by genome-wide divergence in the blind mole rat Spalax.

    Science.gov (United States)

    Li, Kexin; Hong, Wei; Jiao, Hengwu; Wang, Guo-Dong; Rodriguez, Karl A; Buffenstein, Rochelle; Zhao, Yang; Nevo, Eviatar; Zhao, Huabin

    2015-09-22

    Sympatric speciation (SS), i.e., speciation within a freely breeding population or in contiguous populations, was first proposed by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection] and is still controversial despite theoretical support [Gavrilets S (2004) Fitness Landscapes and the Origin of Species (MPB-41)] and mounting empirical evidence. Speciation of subterranean mammals generally, including the genus Spalax, was considered hitherto allopatric, whereby new species arise primarily through geographic isolation. Here we show in Spalax a case of genome-wide divergence analysis in mammals, demonstrating that SS in continuous populations, with gene flow, encompasses multiple widespread genomic adaptive complexes, associated with the sharply divergent ecologies. The two abutting soil populations of S. galili in northern Israel habituate the ancestral Senonian chalk population and abutting derivative Plio-Pleistocene basalt population. Population divergence originated ∼0.2-0.4 Mya based on both nuclear and mitochondrial genome analyses. Population structure analysis displayed two distinctly divergent clusters of chalk and basalt populations. Natural selection has acted on 300+ genes across the genome, diverging Spalax chalk and basalt soil populations. Gene ontology enrichment analysis highlights strong but differential soil population adaptive complexes: in basalt, sensory perception, musculature, metabolism, and energetics, and in chalk, nutrition and neurogenetics are outstanding. Population differentiation of chemoreceptor genes suggests intersoil population's mate and habitat choice substantiating SS. Importantly, distinctions in protein degradation may also contribute to SS. Natural selection and natural genetic engineering [Shapiro JA (2011) Evolution: A View From the 21st Century] overrule gene flow, evolving divergent ecological adaptive complexes. Sharp ecological divergences abound in nature; therefore, SS appears to be an

  1. Groundwater flood or groundwater-induced flood?

    OpenAIRE

    Robins, N.S.; Finch, J. W.

    2012-01-01

    A number of ‘groundwater flood’ events have been recorded over the Chalk aquifer in southern England since the 1994 occurrence at Chichester, Sussex. Reporting of this event and subsequent groundwater floods indicates that there are two types of groundwater flood event. Type 1 is the true groundwater flood in which the water table elevation rises above the ground elevation, and Type 2 occurs when intense groundwater discharge via bourne springs and highly permeable shallow horizons discharges...

  2. Proceedings of the fifth international conference on CANDU fuel. V.1,2

    Energy Technology Data Exchange (ETDEWEB)

    Lau, J.H. [ed.

    1997-07-01

    The First International Conference on CANDU Fuel was held in Chalk River in 1986. The CANDU Fuel community has gathered every three years since. The papers presented include topics on international experience, CANFLEX fuel bundles, Fuel design, Fuel modelling, Manufacturing and Quality assurance, Fuel performance and Safety, Fuel cycles and Spent Fuel management. Volume One was published in advance of the conference and Volume Two was printed after the conference.

  3. Más sobre alfabetización informacional

    OpenAIRE

    Licea de Arenas, Judith; Gómez Hernández, José Antonio; Valles Valenzuela, Francisco Javier

    2009-01-01

    The search for incentives to promote the use of information resources, their identification, evaluation, understanding and usage amongst library users and non users is not new. However, the expression information literacy is relatively new and quite common nowadays because of the Internet and the accessibility to intranets and extranets. In this context librarians have to exert good practices in order to contribute to the elimination of teaching activities based on the chalk and the blackboar...

  4. A Novel Architecture for Intrusion Detection in Mobile Ad hoc Network

    OpenAIRE

    Atul Patel; Ruchi Kansara; Dr. Paresh Virparia

    2011-01-01

    Today’s wireless networks are vulnerable in many ways including illegal use, unauthorized access, denial of service attacks, eavesdropping so called war chalking. These problems are one of the main issues for wider uses of wireless network. On wired network intruder can access by wire but in wireless it has possibilities to access the computer anywhere in neighborhood. However, securing MANETs is highly challenging issue due to their inherent characteristics. Intrusion detection is an importa...

  5. Progress report: Physics Division, 1982 January 1 to March 1

    International Nuclear Information System (INIS)

    The work of the Physics Division at Chalk River Nuclear Laboratories during the quarter is presented. Areas of interest include nuclear physics, neutron sources, the development of a superconducting cyclotron, high current proton accelerators and electron accelerators, diffraction studies and other solid state physics work in organic and inorganic substances, and computer codes. The operation of the MP tandem accelerator and the computer facilities is reviewed

  6. Multi-model comparison of a major flood in the groundwater-fed basin of the Somme River (France)

    OpenAIRE

    Habets, F.; S. Gascoin; S. Korkmaz; Thiéry, D.; Zribi, M.; Amraoui, N.; Carli, M; Ducharne, A; E. Leblois; E. Ledoux; martin, E.; Noilhan, J.; Ottlé, C; Viennot, P.

    2010-01-01

    The Somme River Basin is located above a chalk aquifer and the discharge of the somme River is highly influenced by groundwater inflow (90% of river discharge is baseflow). In 2001, the Somme River Basin suffered from a major flood causing damages estimated to 100 million euro (Deneux and Martin, 2001). The purpose of the present research is to evaluate the ability of four hydrologic models to reproduce flood events in the Somme River Basin over an 18-year period, by comparison...

  7. Aerated concrete on basis of volcanic rocks waste as efficient thermal insulation material

    OpenAIRE

    Harutyunyan, Anahit

    2015-01-01

    Construction materials and particularly construction items make 50-60% of overall construction costs. Choosing of effective environmentally friendly building materials based on resource and energy-saving technologies enables to significantly reduce prime cost of construction. Raw materials for manufacturing of construction items should be environmentally friendly widespread and cheap. And therefore raw materials like water, sand and carbonate minerals (limestone, chalk, marl) as well as produ...

  8. Medical isotopes and emerging nuclear medicine technologies

    International Nuclear Information System (INIS)

    This presentation discusses medical isotopes and the emerging nuclear medicine technologies as well as the impact of Chalk River reactor shutdown on patient management and diseases. It outlines the chain of supply of isotopes across the globe and isotope shortage impact. It recommends the following mitigating strategies: modifications of scanning techniques, adjustment of patient scheduling, optimization of Tc-99m generator use, patient prioritization, alternate procedures and PET scanning.

  9. Modelling relationships between habitat and dynamics of a wild brown trout (Salmo trutta L.) population in the River Piddle, Dorset, UK

    OpenAIRE

    Burrows, Andrew

    2006-01-01

    The status of "wild" brown trout (Salmo trutta, L. 1758) populations in the UK is increasingly giving cause for concern (Giles, 1989; Crisp; 1993). Declines in freshwater stocks are often associated with anthropogenic influences destructive to river channel structure and ecosystem function which are contributing to widespread loss of salmonid habitats (Crisp, 1989; White, 2002). Chalk streams are subject to considerable habitat degradation such that rehabilitation requires management actions ...

  10. ‘Good Building’: Bertolt Brecht’s Utopian Historical Optimism at the End of World War II

    OpenAIRE

    2011-01-01

    The article focuses on the works of Bertolt Brecht which depicts his insights regarding the reconstruction of Germany. Such works include the story "The City Builder" and the plays "Caucasian Chalk Circle" and "The Days of the Commune." It discusses his principles of what he considers as good building as well as the three criteria addressed in good building which include size, time, and beauty.

  11. Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss in insect biodiversity

    OpenAIRE

    Brooks, David R; Bater, John E.; Clark, Suzanne J.; Monteith, Don T.; Andrews, Christopher; Corbett, Stuart J.; Beaumont, Deborah A.; Chapman, Jason W.

    2012-01-01

    1. Carabid beetles are important functional components of many terrestrial ecosystems. Here, we describe the first long-term, wide-scale and quantitative assessment of temporal changes in UK carabid communities, to inform nationwide management aimed at their conservation. 2. Multivariate and mixed models were used to assess temporal trends over a 15-year period,across eleven sites in the UK Environmental Change Network. Sites covered pasture, field margins, chalk downland, woodland and hed...

  12. Assessing the drivers of dissolved organic matter export from two contrasting lowland catchments, U.K.

    Science.gov (United States)

    Yates, Christopher A; Johnes, Penny J; Spencer, Robert G M

    2016-11-01

    Two lowland catchments in the U.K. were sampled throughout 2010-11 to investigate the dominant controls on dissolved organic matter quantity and composition. The catchments had marked differences in terms of nutrient status, land cover and contrasting lithologies resulting in differences in the dominant flow pathways (groundwater vs. surface water dominated). The Upper Wylye is a chalk stream with a baseflow index of 0.98, draining a catchment dominated by intensive agricultural production. Millersford Brook is a lowland peat catchment with a baseflow index of 0.43, draining a semi-natural catchment with heather moorland and coniferous forest. Samples were collected weekly between October 2010 and September 2011 from eleven sampling locations. Samples were analysed to determine dissolved organic carbon, nitrogen and phosphorus fractions with DOM composition evaluated via the DOC:DON ratio, DOC:DOP ratio, specific UV absorption at 254nm, absorbance ratio (a250:a365) and the spectral slope parameter between 350 and 400nm (S350-400). Significant differences were observed in all determinands between the catchments, over time, and spatially along nutrient enrichment and geoclimatic gradients. Seasonal variation in preferential flow pathways mobilising groundwater-derived DOM were identified as likely controls on the delivery of DOM in the permeable chalk dominated catchment. Steeper S350-400 values and elevated a250:a365 ratios in this catchment suggest material of a lower bulk aromatic C content and molecular weight delivered during the winter months when compared to the summer. DOC:DON ratios were markedly lower in the chalk catchment than the peatland catchment, reflecting the paucity of organic matter within the mineral soils of the chalk landscape, and higher fertiliser application rates. This manuscript highlights that DOM composition varies according to catchment landscape character and hydrological function. PMID:27422728

  13. ‘Good Building’: Bertolt Brecht’s Utopian Historical Optimism at the End of World War II

    Directory of Open Access Journals (Sweden)

    Gerhard Fischer

    2011-04-01

    Full Text Available The article focuses on the works of Bertolt Brecht which depicts his insights regarding the reconstruction of Germany. Such works include the story "The City Builder" and the plays "Caucasian Chalk Circle" and "The Days of the Commune." It discusses his principles of what he considers as good building as well as the three criteria addressed in good building which include size, time, and beauty.

  14. Combined rock slope stability and shallow landslide susceptibility assessment of the Jasmund cliff area (Rügen Island, Germany)

    OpenAIRE

    Günther, A.; Thiel, C

    2009-01-01

    In this contribution we evaluated both the structurally-controlled failure susceptibility of the fractured Cretaceous chalk rocks and the topographically-controlled shallow landslide susceptibility of the overlying glacial sediments for the Jasmund cliff area on Rügen Island, Germany. We employed a combined methodology involving spatially distributed kinematical rock slope failure testing with tectonic fabric data, and both physically- and inventory-based shallow landslide susceptibility anal...

  15. A theoretical reflection on the implications of the philosophy of technology for classroompedagogy

    OpenAIRE

    Piet Ankiewicz

    2013-01-01

    Learning programmes for technology education and its facilitation at chalk leveloften lack a scientifically founded, subject-based, philosophical framework. Matters arecomplicated by the fact that technology at school level is globally a developing subject withno existing equivalent academic discipline which can serve as a source of curriculumdevelopment and classroom pedagogy to rely upon in practice. The purpose of the article wasto do an investigation into a philosophical framework of tech...

  16. E-learning in Type 1 Medical Universities of Iran

    OpenAIRE

    Mohammad Bagher ROKNI

    2005-01-01

    ABSTRACT Nowadays the Internet is the technological pedestal of organization in the information society and one of the main applications that the Internet offers is the Digital Library (DL). Each society, especially those that claim training of the public, predictably need implementation and endorsement these systems. The time of chalk and board is passed and the globalization and universal village demands a movement targeting to establish an information society. The university is sai...

  17. Impact of past experiences on engineering a shallow land burial facility

    International Nuclear Information System (INIS)

    Past experiences with in-ground storage and disposal of low-level radioactive wastes at Chalk River Nuclear Laboratories (CRNL) and elsewhere have provided valuable lessons relevant to the design of future disposal systems. This paper reviews the related past experiences and discusses their impact on engineering disposal systems in general, as well as the impact on the conceptual design of CRNL's planned shallow land burial facility

  18. Groundwater risk assessment for a Polycyclic Aromatic Hydrocarbons (PAH) contaminated site ; benchmarking and validation of numerical transport models

    OpenAIRE

    Rollin, Claire; Baroudi, Hafid; Ben Slimane, Férid

    2001-01-01

    The objective is to test the modelling approaches and the reliability of the codes used in water risk assessment. The final goal is to elaborate, for each group of pollutant, guidelines that could serve as a scientific support for pollutant transport modelling in groundwater and soil. The models performed by 5 teams to simulate a contamination of soils and groundwaters by PAH at a disused coke plant site were compared. Hydrogeology is characterised by a superficial and a chalk aquifer, the la...

  19. MICROECONOMICS MADE SIMPLE FOR JUNIOR UNDERGRADUATES OF BUSINESS, ECONOMICS AND MARKETING

    OpenAIRE

    Carlos Osorio

    2004-01-01

    This article reports how a two-term obligatory Microeconomics at the Universidade da Beira Interior, Portugal, has been taught for junior undergraduates of the three degrees: Business, Economics and Marketing, offered by the Department of Business and Economics. It reveals the trade-off between e-teaching, with intensive use of new information and communication techs, and the utilization of traditional tools: hand- outs, chalk and blackboard.

  20. A self-portrait of young Leonardo

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    One of the most famous drawings by Leonardo da Vinci is a self-portrait in red chalk, where he looks quite old. In fact, there is a sketch in one of his notebooks, partially covered by written notes, that can be a self-portrait of the artist when he was young. The use of image processing, to remove the handwritten text and improve the image, allows a comparison of the two portraits.

  1. Use of GeoGebra in Primary Math Education in Lithuania: An Exploratory Study from Teachers' Perspective

    OpenAIRE

    Inga ŽILINSKIENĖ; Demirbilek, Muhammet

    2015-01-01

    With the advance of information and communications technologies, new teaching tools are becoming more pervasive. These tools can be utilized in a variety of ways to improve and enhance math teaching. Considering the integration of technology in teaching mathematics, it is clear that the replacement of board and chalk with digital presentation material does not cover all the aspects of the mathematic subjects. One of the important prerequisites for quality of integration technology into mathem...

  2. Setting up the water chemistry for thermal water treatment

    Science.gov (United States)

    Boglovskii, A. V.; Chernozubov, V. B.; Chernykh, N. E.; Gorbunov, A. V.; Birdin, R. Kh.

    2007-07-01

    Results are presented from the development and setting up of water-chemistry conditions for a thermal water treatment process that allows saline effluents from a boiler house to be eliminated. Peculiarities of reducing scale formation in the evaporator through the use of chalk primer and type PAF-13A antiscale agent are discussed. The results of industrial tests of a thermal water treatment plant are presented that confirm the possibility of producing makeup water for heating networks and steam boilers.

  3. Proceedings of the fifth international conference on CANDU fuel. V.1,2

    International Nuclear Information System (INIS)

    The First International Conference on CANDU Fuel was held in Chalk River in 1986. The CANDU Fuel community has gathered every three years since. The papers presented include topics on international experience, CANFLEX fuel bundles, Fuel design, Fuel modelling, Manufacturing and Quality assurance, Fuel performance and Safety, Fuel cycles and Spent Fuel management. Volume One was published in advance of the conference and Volume Two was printed after the conference

  4. One-sided muon tomography - A portable method for imaging critical infrastructure with a single muon detector

    OpenAIRE

    Boniface, K.; Anghel, V. N. P.; Erlandson, A.; Jonkmans, G.; Thompson, M; Livingstone, S.

    2016-01-01

    High-energy muons generated from cosmic-ray particle showers have been shown to exhibit properties ideal for imaging the interior of large structures. This paper explores the possibility of using a single portable muon detector in conjunction with image reconstruction methods used in nuclear medicine to reconstruct a 3D image of the interior of critical infrastructure such as the Zero Energy Deuterium (ZED-2) research reactor at Canadian Nuclear Laboratories' Chalk River site. The ZED-2 react...

  5. 可擦性无尘笔用水性白墨水

    Institute of Scientific and Technical Information of China (English)

    陈登龙; 郑昌辉

    2003-01-01

    Chalk is the ordinary cheap writing material. The dust it produces in using does a great harm to teachers and students. The dust pollutes the environment. To solve the problem, an erasable dust-free pen ink has been invented. It has a wide choice of colour. The ink is consist of an organic solvent and some other dyestuffs. The ink enables users to keep away from pollution.

  6. Effect of flow obstacles with various leading and trailing edges on critical heat flux

    International Nuclear Information System (INIS)

    A joint investigation has been performed by the University of Ottawa and Chalk River Laboratories that examined the effect of the shape of the leading and trailing edges of the turbulence enhancing devices ('flow obstacles') on critical heat flux (CHF). The objective of this study was to gain a better overall understanding of the limit of CHF improvement for various obstacle designs and the impact of flow conditions on the improvements. (author)

  7. Field test of wireless sensor network in the nuclear environment

    Energy Technology Data Exchange (ETDEWEB)

    Li, L., E-mail: lil@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Wang, Q.; Bari, A. [Univ. of Western Ontario, London, Ontario (Canada); Deng, C.; Chen, D. [Univ. of Electronic Science and Technology of China, Chengdu, Sichuan (China); Jiang, J. [Univ. of Western Ontario, London, Ontario (Canada); Alexander, Q.; Sur, B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2014-06-15

    Wireless sensor networks (WSNs) are appealing options for the health monitoring of nuclear power plants due to their low cost and flexibility. Before they can be used in highly regulated nuclear environments, their reliability in the nuclear environment and compatibility with existing devices have to be assessed. In situ electromagnetic interference tests, wireless signal propagation tests, and nuclear radiation hardness tests conducted on candidate WSN systems at AECL Chalk River Labs are presented. The results are favourable to WSN in nuclear applications. (author)

  8. Attitude of medical students towards the use of audio visual aids during didactic lectures in pharmacology in a medical college of central India

    OpenAIRE

    Mehul Agrawal; Rajanish Kumar Sankdia

    2016-01-01

    Background: Students favour teaching methods employing audio visual aids over didactic lectures not using these aids. However, the optimum use of audio visual aids is essential for deriving their benefits. During a lecture, both the visual and auditory senses are used to absorb information. Different methods of lecture are and ndash; chalk and board, power point presentations (PPT) and mix of aids. This study was done to know the students' preference regarding the various audio visual aids, ...

  9. Traditional education vs modern education. What is the impact of teaching techniques' evolution on students learning process?

    OpenAIRE

    Campo Yagüe, José María del; Negro Valdecantos, Vicente; Nuñez, Miguel

    2012-01-01

    The main objective of this article is to focus on the analysis of teaching techniques, ranging from the use of the blackboard and chalk in old traditional classes, using slides and overhead projectors in the eighties and use of presentation software in the nineties, to the video, electronic board and network resources nowadays. Furthermore, all the aforementioned, is viewed under the different mentalities in which the teacher conditions the student using the new teaching technique, improving ...

  10. Survey of physics research with a high duty cycle electron accelerator

    International Nuclear Information System (INIS)

    The opportunities for nuclear physics research afforded by a CW electron linac with nominal energy 100 MeV and beam current >= 100 μA equipped with a bremsstrahlung monochromator and reaction product coincidence facilities are outlined. It is proposed that a program toward realization of an accelerator meeting these requirements and with provision for eventual extension to higher energies be undertaken at the Chalk River Nuclear Laboratories. (author)

  11. Upper Campanian and Lower Maastrichtian belemnites from the Mons Basin, Belgium

    OpenAIRE

    Christensen, W.K.

    1999-01-01

    Upper Campanian Belemnitella and Lower Maastrichtian Belemnella and Belemnitella faunas from the chalks of the Mons Basin in Belgium are described, utilizing univariate and bivariate biométrie analyses. The Upper Campanian belemnite faunas comprise six taxa of Belemnitella, including two left in open nomenclature: B. mucronata, B. woodi, B. minor I, B. minor II, B. sp. 1 and B. sp. 2. The lower Lower Maastrichtian fauna includes Belemnella (Pachybelemnella) obtusa with subordinate Belemnitell...

  12. "Cherry red spot" in a patient with Tay-Sachs disease: case report "Mácula em cereja" em paciente com doença de Tay-Sachs: relato de caso

    OpenAIRE

    Ricardo Evangelista Marrocos de Aragão; Régia Maria Gondim Ramos; Felipe Bezerra Alves Pereira; Andreya Ferreira Rodrigues Bezerra; Daniel Nogueira Fernandes

    2009-01-01

    Tay-Sachs disease is an autosomal recessive disorder of sphingolipid metabolism, caused by enzime hexosaminidase A deficiency that leads to an accumulation of GM2 in neurocytes which results in progressive loss of neurological function. The accumulation of lipid in retinal ganglion cells that leads to a chalk-white appearance of the fundus called "cherry red spot" is the hallmark of Tay-Sachs disease. It is also seen in others neurometabolic diseases as well as in central retinal artery occlu...

  13. Robust evidence for random fractal scaling of ground water levels in unconfined aquifers

    OpenAIRE

    Little, Max A.; Bloomfield, John P.

    2010-01-01

    This study introduces new approaches to improve the statistical robustness of techniques for quantifying the fractal scaling of groundwater levels, and uses these techniques to investigate scaling of groundwater levels from a consolidated permeable carbonate aquifer. Six groundwater level time series and an associated river stage time series from the unconfined Chalk aquifer (a dual-porosity, fractured limestone aquifer) in the Pang–Lambourn catchment, UK, have been analysed. Surrogate data o...

  14. Paper, Video, Internet: New Technologies for Research and Teaching in Archaeology: The Sphakia Survey

    OpenAIRE

    Nixon, Lucia; Price, Simon

    2004-01-01

    Abstract: Archaeology has always been a multimedia discipline in terms of teaching and publication. From the earliest days of archaeology as an academic subject, archaeologists have used museum collections, slides, and actual site visits as well as 'chalk and talk' for teaching. Archaeological publications are almost always illustrated. The Sphakia Survey is an interdisciplinary archaeological project whose main objective is to reconstruct the sequence of human activity in a remote and rug...

  15. Grain Quality Evaluation and Organoleptic Analysis of Aromatic Rice Varieties of Goa, India

    OpenAIRE

    Shilpa J Bhonsle; Krishnan Sellappan

    2010-01-01

    Rice grain quality characteristics such as physical (hulling, length and breadth (L/B), grain classification,chalkiness, chalk index), chemical (alkali spreading value (ASV), amylose content (AC), gel consistency (GC),aroma), cooking (volume expansion, elongation ratio (ER), water uptake) and organoleptic-tests based onconsumer preferences like appearance, cohesiveness, tenderness on touching, chewing, taste, aroma, elongationand overall acceptability were studied for fourteen aromatic rice v...

  16. THE USE OF MULTI – MEDIA IN ENGLISH LANGUAGE TEACHING

    OpenAIRE

    ARVIND VASANTRAO DESHMUKH

    2012-01-01

    Multimedia teaching method has been used in college English teaching wider and wider. It has contributed a lot to higher teaching quality. Chalk and Talk teaching method is not enough to teach English effectively. We should change our teaching ideas and recognize its impersonal attribute as one kind of teaching method. Thus we can utilize modern education technology reasonably to fulfill the target of college English teaching.

  17. Properties of rotational bands at the spin limit in A {approximately} 50, A {approximately} 65 and A {approximately} 110 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Janzen, V.P.; Andrews, H.R.; Ball, G.C. [Chalk River Labs., Ontario (Canada)] [and others

    1996-12-31

    There is now widespread evidence for the smooth termination of rotational bands in A {approx_equal} 110 nuclei at spins of 40-to-50{Dirac_h}s. The characteristics of these bands are compared to those of bands recently observed to high spin in {sup 64}Zn and {sup 48}Cr, studied with the 8{pi} {gamma}-ray spectrometer coupled to the Chalk River miniball charged-particle-detector array.

  18. Progress report, October 1 to December 31, 1959. Physics Division

    International Nuclear Information System (INIS)

    This is a progress report of the Physics Division at Chalk River Nuclear Laboratories from October 1, to December 31, 1959. It describes the research in nuclear physics, general physics, theoretical physics and electronics. The research areas covered in this report include nuclear structure, the tandem accelerator, particle detector development, developments in electronics, neutron decay, beta ray spectrometer, fission studies, electronics development and neutron transport theory.

  19. Progress report April 1, to June 30, 1956. Physics Division

    International Nuclear Information System (INIS)

    This is a progress report of the Physics Division at Chalk River Nuclear Laboratories from April 1, to June 30, 1956. It describes the research in nuclear physics, general physics; theoretical physics and electronics. The research areas covered in this report include nuclear reactions, nuclear decay, neutron capture gamma ray spectra, NRX production of plutonium and its higher isotopes, slow neutron spectrometry, neutron diffraction, gamma ray crystal spectrometry, theory of binary fission and analysis of neutron scattering data.

  20. Canada enters the nuclear age: a technical history of Atomic Energy of Canada limited as seen from its research laboratories

    International Nuclear Information System (INIS)

    A technical history of Atomic Energy of Canada Limited written by sixteen of Canada's pioneering nuclear scientists, Canada Enters the Nuclear Age focuses on Canada's nuclear program at AECL's laboratories at Chalk River, Ontario and Whiteshell, Manitoba between the years 1943 and 1985. Topics include the organization and operations of AECL's laboratories, nuclear safety and radiation protection, radioisotopes, basic research, development of the CANDU reactor, and management of radioactive wastes. 7 tabs., 132 figs