bluuebunny/crossref_metadata_2025_split huggingface dataset:
Current-Voltage Characteristics-What Do Experiments Really Tell Us?
Authors: Shapiro Finley R. , Silver Marvin 
Published: March 2011

ABSTRACTExperimentally measured current-voltage measurements in amorphous silicon hydride pin diodes have been fit to computer simulations by Hack and den Boer [1] using relatively small values for the neutral and charged trap capture rates. Silver and Cannella [2] have proposed larger values for the capture rates, accompanied by larger electron and hole band mobilities. We discuss here the possible reasons for expecting the larger values for the capture rates, and their influence on current voltage measurements both with and without the higher mobilities. It is found that the simulated I-V results using only the larger capture rates are much smaller than those for Hack and den Boer's parameters. However, when the large values are used for both the capture rates and the mobilities, the I-V relationship is quite similar to that for the smaller capture rates and mobilities. We also show the differences in the simulated transient currents for the different sets of parameters, and we discuss the causes of these differences.
High-Quality A-Si Films Prepared by the Direct Photo-Cvd Method
Authors: Nakano S. , Wakisaka K. , Kameda M. , Isomura M. , Matsuyama T. , Nakamura N. , Tsuda S. , Ohnishi M. , Kuwano Y. 
Published: March 2011

ABSTRACTA high-efficiency integrated-type a-Si solar cell submodule with a size of 10cm × 10cm has been fabricated and a total area efficiency of 9.6% is obtained by using a high-quality p-layer doped with B(CH3)3 We have developed an advanced direct photo-CVD method. High-quallt” a-SI films with low tail characteristic energy and low light-induced degradation is prepared by this method. We have also studied the role of Si-H2 bonds on the light-induced effect. The result implies that Si-H bonds stabilize the defect states, resulting in a large light-induced degradation.
Preparation and Evaluation of p-Type Materials for a-Si Solar Cells Using DC Plasma Discharge Deposition of Trimethylboron (B(CH3)3)
Authors: Fieselmann Benjamin F. , Goldstein B. 
Published: March 2011

ABSTRACTAmorphous SiC p-layers doped with trimethylboron (B(CH3) 3) were prepared with optical and electrical properties superior to those prepared with B2H6. Devices were prepared with efficiencies as high as 11.4% using trimethyl boron. The improved properties of B(CH3)3-doped a-SiC result from the fact that trimethylboron is a more effective doping agent than B2H6 and produces p-layers with a higher bandgap.
Cpm Measurenents on a-Si:H Based Pin Solar Cells: Thickness and Bias Voltage Effects
Authors: Rübel H. , Gorn M. , Scheppat B. , Geyer R. , Lechner P. , Kniffler N. 
Published: March 2011

ABSTRACTWe use measurements of subbandgap photocurrent spectra on films, barrier structures and pin cells of different thicknesses to estimate the valence band tailing and to characterize the dangling bond defect region. Large differences in signal sizes in the structures are observed and particularly for thick and thin pin-diodes, the dependence of the signal on voltage bias is discussed. In pin-diodes, these effects can be explained by a change of defect occupation in the i-layer.
Raman Spectroscopy of a.SiGe:H Alloys
Authors: Yang L. , Newton J. , Fieselmann B. 
Published: March 2011

ABSTRACTRaman spectroscopy is used to characterize the microscopic bonding structure of a-SiGe:H alloys. Excess Ge-Ge bonding over what is predicted for random alloys is observed. Correlation between the degree of Ge-Ge clustering and the transport properties of the alloys is demonstrated. Implications of the experimental findings regarding improvement in the quality of the alloy material are discussed.
Photoluminescence of Amorphous Hydrogenated Carbon Films, a-C:H
Authors: Vassilyev V. A. , Volkov A. S. , Musabekov E. , Terukov E. I. , Chelnokov V. E. , Chernyshov S. V. 
Published: March 2011

ABSTRACTResults are presented on the photoluminescence of plasma deposited amorphous carbon (a-C:H) films. Emission and exci tation spectra anti-Stokes emission, PL decay and fatigue, T-dependence of PL and photobleaching were mesuared. The data are discussed in terms of radiative recombination of the strongly localized electron-hole pairs.As recently shown, in amorphous hydrogenated carbon films (a-C:H) powerful talls of localized states occur in the mobility gap that are due to a high degree of structural disorder [1] while a radiative recombination in this material is highly efficient [2, 3]. These properties, in our view, make a-C:H suitable for verification of models of recombination kinetics of photoexcited charge carriers in highly disordered systems with the use of photoluminescence (PL).
Proton and Neutron Damage in Thick Amorphous Silicon Diodes
Authors: Hollingsworth R. E. , Xi J. , Madan A. , Cecil F. E. 
Published: March 2011

ABSTRACTThin film amorphous silicon diodes are being examined as a possible high energy particle detector for use in the superconducting super collider. One of the key requirements for any such detector is the ability to withstand relatively high doses of high energy particles without degradation of performance. We report here results of degradation studies of amorphous silicon p-i-n diodes to protons and neutrons with energies in excess of 100 keV.
Raman Studies of a-Si:H/a-SiNx and a-Si/a-SiNx Superlattices
Authors: Honma I. , Tanaka T. , Komiyama H. , Tanaka K. 
Published: March 2011

ABSTRACTFirst observation is reported of the deposition rate dependence of Raman-detected structural disorder in a-Si:H/a-SiNx semiconductor superlattices as well as a-Si/a-SiNx ones. FWHM of TO-like Raman peak of a-Si:H in the multilayer structure rapidly decreases as deposition rate decreases, while that of a- Si decreases more slowly. The results demonstrate that the structural disorder of a-Si:H/a-SiNx decreases as time to grow a monolayer (TGM) increases in a time range of a second, and also suggest that hydrogen covering the growing surface enhances the structural-relaxation velocity of disordered amorphous network.
Dissolution and Reaction studies of Cszr2(PO4)3 and Zr Phosphates in Aqueous Media
Authors: Vance E.R. , Ahmad J. 
Published: March 2011

ABSTRACTCs dissolution kinetics for Cszr2(PO4)3 in a variety of aqueous media at 70°C approximately obeyed a first-order law. However in 0.1 M NaHCO3,at1/2 law was appropriate. The Cs extraction was a minimum under neutral conditions. In the pH range of 1–4, the Cs extraction varied approximately as [H+]0.3 and was a stronger function of pH in alkaline media.
The survival of α-Zr phosphate gel in water at 300°C was essentially confirmed. ZrP2O7, reacted sluggishly with water at 200–300°C to produce an apparently fully-protonated analogue of NaZr2(PO4)3
Theory of Corrosion of Alkali-Borosilicate Glass
Authors: Clark David E. , Hench Larry L. 
Published: March 2011

ABSTRACTThe alkali-borosilicate (ABS) system provides the basis for a wide variety of commercially important products among which are the nuclear waste glasses. Although a large number of investigations have been undertaken in the last five years, the corrosion mechanisms of the ABS glasses have not been characterized nearly as well as for the soda-lime-silicate (NCS) glasses commonly used for containers. It is well known that the corrosion of the latter glasses involves ion exchange, network dissolution, and precipitation mechanisms resulting in the development of one of five types of surface films. In the present paper we compare the corrosion behavior to the ABS and NCS glasses and discuss our current understanding of ABS glass corrosion in terms of mechanisms, kinetics, surface film formation and thermodynamics.
Effects of Solution Chemistry and Atmosphere on Leaching of Alkali Borosilicate Glass
Authors: Hermansson Hans-Peter , Christensen Hilbert , Clark David E. , Werme Lars 
Published: March 2011

ABSTRACTThe leaching behavior of two alkali-borosilicate glasses containing 9 wt% simulated fission products and 1.6 wt% uranium oxide has been studied. Samples were exposed to one of eight types of leachants including doubly distilled water, simulated ground silicate water, a brine solution, and solutions containing various concentrations of iron, aluminium or sodium maintained at either 25°C, 40°C or 90°C for up to 182 days. The most aggressive leachants were the solutions containing sodium (excluding brine) and simulated ground silicate water. These solutions increased the extent of leaching by a factor of 2–3 over that for distilled water for one of the glasses. A partially protective surface film rich in magnesium potassium and chlorine was formed on the glasses exposed to the brine solution.In order to evaluate the effects of atmosphere on leaching, samples were also immersed in doubly distilled water over which the relative concentrations of oxygen, nitrogen and carbon dioxide were varied. Increasing the carbon dioxide concentration from 0 to 50% resulted in a factor of 3 increase in the leaching rate.
Extended Leach Studies of Actinide-Doped SRL 131 Glass
Authors: Bates John K. , Lam Daniel J. , Steindler Martin J. 
Published: March 2011

ABSTRACTThe effects on the leachability of SRL 131 glass as a result of slight changes in the glass composition were monitored by leachate and surface analyses. The compositional changes had marked effects on solution and layer composition and on the precipitated alteration products that formed after 546 days of static leaching. The leaching behavior of long-lived actinide elements were measured, with Pu and Am showing little tendency to become solubilized and Np and U continuously accumulating in solution.
Natural Analogues—A Way to Increase Confidence in Predictions of Long-Term Performance of Radioactive Waste Disposal
Authors: Birchard G. F. , Alexander D. H. 
Published: March 2011

ABSTRACTNo exact analogue to a radioactive waste disposal system exists but by studying natural analogues of the most important components or subsystems of a waste repository, confidence in long-term predictions can be increased. The U.S. Nuclear Regulatory Commission (NRC) is supporting research on igneous intrusions into proposed repository-type host rock (basalt, tuff, crystalline hard-rock, and salt), on uranium ore body analogues, on actinide solubility as a function of natural complexing agents in closed basin lakes and on field migration of radionuclide species at low-level waste and uranium mill tailings disposal sites. The NRC is studying analogues to ensure that important parameters which might be overlooked in laboratory tests and in modeling because of problems with scaling time, space and geologic complexity can be identified and their importance bounded.
Nuclear Waste Management in France
Authors: Lefevre J. , Sugier A. 
Published: March 2011

On October 6, and 7 1982, after a two-day Parliamentary Debate, the continuation of the French nuclear power program was approved. Installed nuclear capacities, should reach 56000 elMN by 1990, i.e. 28% of energy supplies.The nuclear waste volumes entailed by such a nuclear electricity program, with the accompanying fuel cycle operations and the other nuclear waste producing activities, are the following: Low and Medium Level waste volumes should reach 800,000 cubic meters by the year 2000 - slightly less than was planned for two years ago, because of reduced power consumption, and therefore capacities forecasts. Alpha-bearing and vitrified Wastes should reach respectively 45,000 cubic meters and 3,000 cubic meters by the year 2000.These waste quantities now make it urgent to set up a wholly comprehensive industrial scale program for their treatment, conditioning and final disposal, together with the relevant research and development activities.
United Kingdom Regulatory Procedures for Radioactive Wastes
Authors: Feates F S , Richards H J 
Published: March 2011

ABSTRACTIn the United Kingdom the responsibility for radioactive waste management policy lies with the environmental Ministers. The Department of the Environment is also responsible in England for authorisation of all radioactive waste disposal activities and has its own Radiochemical Inspectorate to ensure that government policy is implemented. An independent Radioactive Waste Management Advisory Committee reports directly to the Secretary of State for the Environment.Low-level wastes are currently disposed of by shallow burial or to the deep ocean. Sites for the disposal of intermediate-level wastes are being sought as a matter of urgency and heat-emitting, reprocessing wastes will be stored on the surface for at least fifty years. The rationale of this policy is explained.
Radiolysis of Groundwater from HLW Stored in Copper Canisters
Authors: Christensen Hilbert , Bjergbakke Erling 
Published: March 2011

ABSTRACTA large number of computer calculations of the radiolysis of ground water outside copper canisters have been carried out within the Swedish Nuclear Fuel safety Project.At dose rates higher than 5 × 10−2rad/s the hydrggen concentration is constant, approximately 10−3mol/dm3, and independent of time and dose rate. Therefore the rate of difiusion out of the system is constant, approximately 7 × 10−4mol/year. At dose rates lower than 5 × 10−4rad/s the logarithm of the hydrogen production is proportional to the logarithm of the dose rate. The hydrogen production depends on fuel type, burn-up and canister thickness only to the extent that the dose rate varies with these parameters. The hydrogen production is independent of the volume of water in which the energy is assumed to be absorbed (5 or 15 cm layers outside the surface of the canister).The hydrogen production depends on the concentration of Fe2+ions in the water. In the basic calculations the concentration was assumed to be 5 ppm. An increase to 50 ppm increases the total hydrogen production after one million years outside a 1 cm thick canister from 360 to 1000 mol. A decrease to 0.5 ppm decreases the same yield to 80 mol.
Irradiation Effects in the Storage and Disposal of Radioactive Ion-Exchange Resins
Authors: Swyler Karl J. , Dodge Cleveland E. , Dayal Ramesh , Weiss Allen J. 
Published: March 2011

ABSTRACTResearch is under way to characterize the effects of self-irradiation on radwastes which may be generated when organic ion-exchange media are used in water demineralization or decontamination operations at nuclear facilities. External factors affecting the relation between laboratory evaluations and field performance are emphasized. Initial experiments do not yet indicate substantial radiation dose-rate effects on radiolytic gas yields or acid product formation, when (fully swollen) sulfonic acid resins are irradiated in a sealed air environment. At the same time, oxygen gas is removed from the environment of irradiated resins. Interaction between mild steel coupons and acidic species produced in the irradiation induced decomposition of sulfonic acid resin results in irradiation enhanced corrosion. Corrosion rates depend on radiation dose rate, moisture content and resin chemical loading. In some cases, corrosion rates decrease with time, suggesting depletion of acidic species within the resin bed, or a synergistic interaction between resin and corrosion coupon. Implications of these and other results on evaluating field behavior of radwaste containing ion-exchange media are discussed.
Toward a Comprehensive Model of Chemical Transport in Porous Media
Authors: Miller Constance W. 
Published: March 2011

ABSTRACTA chemical transport model, CHEMTRN, that includes advection, dispersion/diffusion, complexation, sorption, precipitation or dissolution of solids, and the dissociation of water has been written. The transport, mass action and site constraint equations are written in a differential/algebraic form and solved simultaneously. The sorption process is modelled by either ion-exchange or surface complexation. The model has been used to investigate the applicability of a kD model for simulating the transport of chemical species in groundwater systems, to simulate precipitation/dissolution of minerals, and to consider the effect of surface complexation on sorption.
Long-Term Thermomechanical and Thermohydrological Factors Controlling the Optimal Design of a Nuclear Waste Repository
Authors: Wang J. S. Y. , Mangold D. C. , Tsang C. F. 
Published: March 2011

ABSTRACTSurface uplift and buoyancy flow are two of the major long-term, far-field perturbations to the geologic formations around a nuclear waste repository. The allowable surface uplift has been accepted in the literature as a criterion limiting the repository waste loading density. It has also been recognized in generic modeling studies that the buoyancy distortion of the ambient groundwater flow around a repository is a major mechanism for radionuclide transport. However, the buoyancy considerations have yet to be quantified for the purpose of optimal design of a radioactive waste repository. We suggest the possibility of using the buoyancy gradient when compared with the ambient regional (horizontal) gradient as a measurable thermohydrologic factor that controls the design of waste loading. This study indicates that the buoyancy gradient could in some cases become the main controlling factor. To decrease the buoyancy effects, much lower values of waste loading density should be considered in the design of the waste repository.
Ceramization of Inorganic Ion Exchangers Loaded with Nuclear-Waste into Red Clay Tiles
Authors: Lehto Jukka , Heinonen Olli J. , Miettinen Jorma K. 
Published: March 2011

ABSTRACTA new method to ceramize inorganic ion exchangers loaded with nuclear waste has been developed. It is simpler and cheaper than methods used previously, e.g. hot pressing. The inorganic ion exchangers, sodium titanate and ZrO2, were turned into final ceramic waste form by mixing them with a Finnish red clay in weight ratio 1:4 at maximum. The tiles moulded frKm the wet, bakeable mixture were ceramized at 1020–1060°C. The leach rates of Sr, Cs and Co from the tiles determind by a 7 dynam c ISO-test were after six months of leaching 10−6−10−7 g/cm2/d, in decreasing order. Mechanically the tiles are very durable: flexural strengths were in the range of 20–45 meganewtons per square meter.
Geophysical Modeling of a Low-Level Nuclear Waste Disposal Site
Authors: Horton Keith A. , Isaacson Louis , Morey Rexford M. 
Published: March 2011

ABSTRACTGeophysical measurements can, depending on the techniques employed, be used at low-level nuclear waste disposal sites to map the subsurface stratigraphy, identify interfaces, locate objects and targets, and aid in selecting locations for obtaining sample cores and placing monitoring wells. The geophysical techniques of ground penetrating radar and electrical resistivity have been applied in a complementary manner at nuclear waste disposal sites. The data obtained from the field surveys have been integrated in developing geophysical models of these sites.A two-layer electromagnetic geologic model has been developed that allows the prediction of radar attenuation and depth of penetration. Field tests conducted at a lowlevel nuclear waste disposal site show values consistent with the model.
Formulation and Durability of Tailored Cenentitious Hosts Applied to TRU Waste Generated at the Rocky Flats Plant
Authors: Kessler J. H. , Rogers G. C. , Dole L. R. , Morgan M. T. 
Published: March 2011

ABSTRACTAt Oak Ridge National Laboratory, we have developed cementitious grout formulations which can incorporate up to 50 wt % of a transuranic (TRU) waste generated during startup operations at the Rocky Flats Plant Building 374, Golden, Colorado. Trial grout mixes were tested in order to minimize the water content and maximize the waste loading. The effects of water reducers and set regulators on these mixes were also examined.Durability and physical property measurements were performed on formulations containing 40 wt % waste, which are compatible with standard processing equipment. The densities, porosities, and compressive strengths of these solids are reported. Compressive strengths of the samples were found to increase by as much as 69% after the sample had been exposed to leachants for 28 d at 900 C.
Alteration of Nuclear Waste Glass by Hydration
Authors: Bates John K. , Steindler Martin J. 
Published: March 2011

ABSTRACTAging of simulated nuclear waste glass by contact with a humid atmosphere results in the formation of a double hydration layer penetrating into the glass and in the formation of alteration products on the glass surface. This hydration process has been studied as a function of time, temperature, glass composition and water vapor pressure. A dual stage hydration rate was observed and rate constants were determined at each temperature. An Arrhenius plot for the initial stage alteration rate indicates the reaction mechanism does not change between the temperature limits of the experiment (120-240°C). This conclusion is supported by the sequence of mineral formation on the surface. This hydration process provides a means of accelerating aging reactions while simulating conditions that may exist in a nuclear waste repository.
Determination of Crystal Site Occupancy in an Improved Synroc-D Ceramic using Analytical Electron Microscopy
Authors: Tafto J. , Clarke D. R. , Spence J. C. H. 
Published: March 2011

ABSTRACTThe rate of radiation damage from radioactive species in nuclear waste ceramics and the long term stability of the crystalline phases may depend on the crystallographic site of the emitting species. It is therefore of importance to determine the site occupancy of the radioactive elements. Hitherto, no established crystallographic technique has been suitable for such studies due to the small grain size and the many different phases in nuclear waste ceramics, such as Synroc. By taking advantage of the fact that an electron beam can be focussed, and the electron intensity localized, to a particular crystal site by electron diffraction, a new technique capable of locating small concentrations of atoms in small crystal volumes >(10 nm)3 has recently been developed. The application of the technique to determining the site occupancy of solutes, including U, Sr, Th, in the perovskite and ulvo-spinel phases of a Synroc ceramic is described. In the perovskite phase, U, Th, Sr, Zr and Mn, are shown to substitute on the Ca site with Fe partitioning between the Ca and Ti sites.
Diamond-Like Films Obtained by Sputtering from a Glassy Carbon Target
Authors: Niemann E. , Herkert R. , Leidich D. 
Published: March 2011

ABSTRACTDiamond-like a-C:H films were obtained by reactive dc-magnetron sputtering from a glassy carbon target in an argon-hydrogen atmosphere. To our knowledge, this is the first time that glassy carbon is used as target material. The a-C:H films are transparent and hard. The a-C:H films can be used as protection and antireflection coatings on a-Si:H photoreceptors. The electrical, optical and structural properties of the a-C:H films are examined.
Determination of the Energy Gap in Photoconducting Insulators Through Current Noise Measuremen
Authors: Carbone A. , Demichelis F. , Mazzetti P. 
Published: March 2011

ABSTRACTMeasurements of the current noise power spectrum of the photoconducting insulators CdS and CdSe irradiated with monochromatic light of different wavelength A are reported.It is shown that there is an abrupt change of about one order of magnitude in the low frequency power density of the noise when A crosses the photoconductor gap value Ag and the photocurrent and the device conductance are kept constant by varying the light intensity.The effect is explained in terms of an abrupt increase of the carrier recombination rate when the photon energy becomes larger than the energy gap of the photoconductor. Possible applications of these results are briefly discussed.