bluuebunny/crossref_metadata_2025_split huggingface dataset:
Migration Behaviour of Ferrous Ion in Compacted Bentonite Under Reducing Conditions Controlled With Potentiostat
Authors: Idemitsu Kazuya , Nessa Syeda Afsarun , Yamazaki Shigeru , Ikeuchi Hirotomo , Inagaki Yaohiro , Arima Tatsumi 
Published: April 2011

AbstractCarbon steel overpack is corroded by consuming oxygen introduced by repository construction after closure of the repository and then maintains the reducing environment in the vicinity of the repository. The migration of iron corrosion products through the buffer material will affect the migration of redox-sensitive radionuclides. Therefore, it is important to study the migration of iron corrosion products through the buffer material because it may affect the corrosion rate of overpack, and migration of redox-sensitive radionuclides. Electromigration experiments have been conducted with the source of iron ions supplied by anode corrosion of the iron coupon in compacted bentonite. The carbon steel coupon was connected as the working electrode to the potentiostat and was held at a constant supplied potential between - 650 to +300 mV vs. Ag/AgCl electrode for up to 168 hours. The amount of iron penetrated into a bentonite specimen was in good agreement with the calculated value from the corrosion current under the assumption that iron is dissolved as ferrous ions. A model using dispersion and electromigration could explain the measured iron profiles in the bentonite specimens. The fitted value of electromigration velocity depended on the potential supplied. On the other hand the fitted value of the dispersion coefficient did not depend on the potential supplied but a constant. This constant dispersion coefficient could be due to the much larger diffusion coefficient of ferrous ion in bentonite compared with the effect of mechanical dispersion. The experimental configurations used in this study are applicable to the examination of the migration behaviour of cations with the source of iron ions under a reducing condition controlled with a potentiostat.
Deep Borehole Disposal of Plutonium
Authors: Gibb Fergus G.F. , Taylor Kathleen J. , Burakov Boris E. 
Published: April 2011

AbstractExcess plutonium not destined for burning as MOX or in Generation IV reactors is both a long-term waste management problem and a security threat. Immobilisation in mineral and ceramic-based waste forms for interim safe storage and eventual disposal is a widely proposed first step. The safest and most secure form of geological disposal for Pu yet suggested is in very deep boreholes and we propose here that the key to successful combination of these immobilisation and disposal concepts is the encapsulation of the waste form in small cylinders of recrystallized granite. The underlying science is discussed and the results of high pressure and temperature experiments on zircon, depleted UO2 and Ce-doped cubic zirconia enclosed in granitic melts are presented. The outcomes of these experiments demonstrate the viability of the proposed solution and that Pu could be successfully isolated from its environment for many millions of years.
Molecular Characterisation of Dissolved Organic Matter (DOM) in Groundwaters from the Äspö Underground Research Laboratory, Sweden: A Novel “Finger Printing Tool for Palaeohydrological Assessment
Authors: Vane Christopher H. , Kim Alexander W. , Milodowski Antoni E. , Smellie John , Tullborg Eva-Lena , West Julia M. 
Published: April 2011

AbstractThe molecular signature of dissolved organic matter (DOM) in groundwaters can be used as a tool when investigating the palaeohydrological response of groundwater systems in relation to changes in recharge environment, and also for examining groundwater compartmentalisation, mixing and transport at underground repositories for radioactive waste. The DOM in groundwaters from two compartmentalised bodies of groundwater of distinctly different origin within the Äspö Underground Research Laboratory (URL), Sweden and in Baltic seawater has been isolated using tangential flow ultrafiltration (TUF) and diafiltration. Recoveries of DOM ranged from 34.7 to 0.1 mg/L with substantial differences in the concentrations of the groundwaters collected only 120 m apart. Analysis by infrared spectroscopy (IR) and pyrolysisgas chromatography-mass spectrometry (Py-GC-MS) of the isolated DOM revealed that the groundwaters contained abundant alkylphenols which may represent heavily decomposed proteins or lignins originating from biopolymers contained within soils. The difference in the distribution and relative abundance of major pyrolysis products groups such as alkyphenols confirmed that the groundwater and Baltic seawater DOM samples were chemically distinct indicating minimal infiltration of marine groundwater derived by recharge from the Baltic or earlier Littorina Sea within the two compartmentalised groundwater bodies.
The Use of Activated Slags as Immobilisation Matrices for ILW
Authors: Milestone NB , Bai Y , Yang C.H. , Shi Y.J. , Li X.C. 
Published: April 2011

AbstractComposite cements where large amounts of blast furnace slag (BFS) replace Portland cement are currently used for immobilisation of ILW. Hydration of BFS is activated by the small amount of OPC present but the amount of reaction that occurs is limited at ambient temperatures. Increasing the temperature increases the hydration of the BFS but large amounts still remain unreacted, leaving a porous matrix where the capillary pores remain filled with a highly alkaline solution. This solution causes corrosion of reactive metals giving rise to expansive reactions and hydrogen release, and it can destroy the structure of zeolites releasing the adsorbed species.Apart from OPC, BFS hydration can be activated by other compounds such as hydroxides, sulphates, silicates, and calcium aluminate cements. The use of these alternatives gives rise to binders such as ettringite and strätlingite which have a different chemistry where the pore solution has a lower pH. Corrosion of metals does not readily occur in these binders. This may be due to the reduced pH but could also arise from the lack of pore water, as these binders bind more water in their structure so that it is not available for transport of ionic species. This extra water binding also has potential for immobilisation of sludges where high w/s ratios are necessitated by the need to transport the sludge.This paper will review some of the alternative activators for slag hydration and present experimental results on several systems where slag has been activated with compounds other than OPC.
Realization of Significant Absorption Enhancement in Thin Film Silicon Solar Cells with Textured Photonic Crystal Backside Reflector
Authors: Zeng Lirong , Bermel Peter , Yi Yasha , Alamariu Bernard A. , Broderick Kurt A. , Liu Jifeng , Hong Ching-yin , Duan Xiaoman , Joannopoulos John , Kimerling Lionel C. 
Published: April 2011

AbstractThe major factor limiting the efficiencies of thin film Si solar cells is their weak absorption of red and near-infrared photons due to short optical path length and indirect bandgap. Powerful light trapping is essential to confine light inside the cell for sufficient absorption. Here we report the first experimental application of a new light trapping scheme, the textured photonic crystal (TPC) backside reflector, to monocrystalline thin film Si solar cells. TPC combines a onedimensional photonic crystal, i.e., a distributed Bragg reflector (DBR), with a reflection grating. The near unity reflectivity of DBR in a wide omnidirectional bandgap and the large angle diffraction by the grating ensures a strong enhancement in the absorption of red and near-infrared photons, leading to significant improvements in cell efficiencies. Measured short circuit current density Jsc was increased by 19% for 5 μm thick cells, and 11% for 20 μm thick cells, compared to theoretical predictions of 28% and 14%, respectively.
Infrared ellipsometric characterization of silicon nitride films on textured Si photovoltaic cells
Authors: Saenger M. F. , Schädel M. , Hofmann T. , Hilfiker J. , Sun J. , Tiwald T. , Schubert M. , Woollam J. A. 
Published: April 2011

AbstractWe present an infrared spectroscopic ellipsometry investigation of SixNyfilms deposited on textured Si substrates employed for photovoltaic cells. A multiple-sample data analysis scheme is used in order to determine the SixNydielectric function and thickness parameters regardless of the surface morphology of the substrate. We observe changes in the dielectric function of the silicon nitride film which suggest variations in the chemical composition of the films depending on the substrate morphology.
A Novel Solution Processable Electron Acceptor, C60(CN)2, for Bulk Heterojunction Photovoltaic Applications
Authors: Koppolu Vaishali R. , Gupta Mool C. , Bagienski Will , Shen Yang , Shu Chunying , Gibson Harry W. , Dorn Harry C. 
Published: April 2011

AbstractPhotovoltaic devices based on soluble conjugated polymers have gained great interest in recent years because of the potential low cost of production and ease of fabrication. PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), a fullerene derivative, has been extensively investigated as a solution processable electron acceptor for bulk-heterojunction (BHJ) photovoltaic devices blended with conjugate polymers like P3HT [poly(3-hexylthiophene)]. Here, we investigated a novel solution processable organic semiconductor, C60(CN)2, as an electron acceptor for bulk heterojunction photovoltaic applications. Optical and electrical properties of C60(CN)2 are studied and compared with PCBM. Blend devices with P3HT and C60(CN)2 have been fabricated and compared with P3HT-PCBM devices. The effect of thermal annealing on the device performance is evaluated. Open circuit voltage, short circuit current, fill factor and total efficiency data are compared with PCBM based devices.
Electrodeposition of Cu2ZnSnS4 Thin Films Using Ionic Liquids
Authors: Chan C.P. , Lam H. , Wong K.Y. , Surya C. 
Published: April 2011

AbstractWe report the growth of Cu2ZnSnS4 (CZTS) thin films by electrodeposition in ionic liquid. Sulfurization was performed in elementary sulfur vapor environment at 450°C for 2 hours. The X-ray diffraction analysis indicated that the film has a stannite structure with preferred grain orientation along (112). Photo-absorption measurement of the sample was performed from 500 nm to 990 nm. It is found that the energy bandgap of the film is about 1.49eV and the absorption coefficient is found to be of the order of 104cm-1.
Effects of Growth Parameters on Surface-morphological, Structural and Electrical Properties of Mo Films by RF Magnetron Sputtering
Authors: Kuo Shou-Yi , Chang Liann-Be , Jeng Ming-Jer , Lin Wei-Ting , Lu Yong-Tian , Hu Sung-Cheng 
Published: April 2011

AbstractThis work reports on the fabrication and characterization of Mo thin films on soda-lime glass substrate grown by reactive RF magnetron sputtering. Film thickness was measured by x-ray step surface profiler. The structural properties and surface morphology were analyzed by x-ray diffraction (XRD), atomic force microscope (AFM) and scanning electron microscopy (SEM). Electrical properties were measured by four-point probe. It was found that the growth parameters, such as argon flow rate, RF power, film thickness, have significant influences on properties of Mo films. The strain on films revealed the complicated relationship with the working pressure, which might be associated with micro structures and impurities. In order to improve the adhesion and electricity, we adopted a two-pressure deposition scheme. The optimal thickness and sheet resistance are νm and 0.12 ω The mechanisms therein will be discussed in detail. Furthermore, we also investigated the diffusion property of Na ion of double Mo films sputtered on soda-lime glass. Our experimental results could lead to better understanding for improving further CIGS-based photovoltaic devices.
Impact of Advanced Fuel Cycles on Geological Disposal
Authors: Marivoet Jan , Weetjens Eef 
Published: April 2011

AbstractIn recent years the increasing oil prices and the need for carbon-free energy to limit global warming have resulted in a revival of interests in nuclear energy. Advanced nuclear fuel cycles are being studied worldwide. They aim at making more efficient use of the available resources, reducing the risk of proliferation of nuclear weapons, and facilitating the management of the resulting radioactive waste. Recently, the Red-Impact project has investigated the impact of a number of representative advanced fuel cycles on radioactive waste management, and more specific on geological disposal. The thermal output of the high-level waste arising from advanced fuel cycles in which all the actinides are recycled is reduced with a factor 3 for a 50 years cooling time and with a factor 5 for a 100 years cooling time in comparison with the spent fuel arising from the once-through fuel cycle. This reduction of the thermal output allows for a significant reduction of the length of the disposal galleries and of the size of the repository. Separation of Cs and Sr drastically reduces further the thermal output of the high-level waste, but it requires a long-term management of those heat generating separated waste streams, which contain the very long-lived 135Cs. Recycling all the actinides strongly reduces the radiotoxicity in the waste, resulting in significantly lower doses to an intruder in the case of a human intrusion into the repository. However, the reduction of radiotoxicity has little impact on the main safety indicator of a geological repository, i.e. the effective dose in the case of the expected evolution scenario; for disposal in clay formations, this dose is essentially due to mobile fission and activation products. The deployment of advanced fuel cycles will necessitate the development of low activation materials for the new nuclear facilities and fuels and of specific waste matrices to condition the high-level and medium-level waste streams that will arise from the advanced reprocessing plants.
Cathodoluminescence of Actinides in Wide Gap Materials
Authors: Zamoryanskaya M.V. , Domracheva Ya.V. , Trofimov A.N. , Burakov B.E. 
Published: April 2011

AbstractSingle crystals and polycrystalline samples of durable actinide host phases such as garnet, zircon, and Ti-pyrochlore doped with varying amounts of U, Pu, Np and Am, were studied by cathodoluminescence (CL) spectroscopy. The following characteristic bands were identified: uranyl-ion [UO2]2+– 495 nm in garnet and pyrochlore; [UO4]2− – 710 nm in garnet; and Am3+ – in garnet and zircon at 550 nm, 614 nm, 740÷750 nm.
Mineralogical Control of the REE Distribution in the Fracture Fillings of an Uranium-Ore (Caceres-Spain)
Authors: Buil Belen , Gomez Paloma , Turrero Maria Jesus , Garralon Antonio 
Published: April 2011

AbstractThe behavior of actinides in a deeply buried radioactive waste cannot be predicted from evidence of their movement in geological environments in the geological past because these elements do not occur naturally in appreciable concentration. A useful means of reducing the uncertainty is to observe the behavior, both past and present, of chemical analogues in geological environment. In this sense, the rare earth elements (REE) have been used to predict the behaviour of actinide series elements in water-rock systems on account of the similar valence and ionic radii and high similarity in its electronic structure.This paper describes the factors that control REE signature in the fracture fillings of an ancient uranium mine (dug granite) located in the Central-Iberian Zone of the Hesperian Massif (Caceres, Spain).The study of REE distribution in the fracture fillings provides interesting information about the REE distribution in the hydrothermal fluids that flow through the system. In order to obtain this information, it is necessary to evaluate the control of different minerals in the total REE content of the fracture fillings.The fracture fillings display a large mineralogical variety dominated by K-feldspars, quartz, plagioclase, micas, monazites, xenotimes, apatites, uraninites, inherited of the granites, and carbonates, quartz, apatites, phyllosilicates, sulphides and Fe-oxihydroxydes, neoformed in successive hydrothermal stages.In general, the fracture fillings present different kind of REE patterns, just as positive or negative Eu anomalies. The REE final distribution in the fracture fillings is controlled by the presence of REE-minerals, both inherited and neoformed, and of carbonates, with great capacity to fractionate HREE in the system. On the other hand, the chemical composition of the carbonates and accessory minerals is responsible, as a last resort, for the Eu anomalie (positive or negative) observed in the fracture fillings.
XAFS of Pu and Hf LIII Edge in Lanthanide-Borosilicate Glass
Authors: Shiryaev A.A. , Zubabichus Ya.V. , Stefanovsky S.V. , Ptashkin A.G. , Marra J.C. 
Published: April 2011

AbstractLanthanide-Borosilicate (LaBS) glass capable to dissolve up to ∼10 wt.% PuO2 is designed for immobilization of plutonium-bearing wastes. The sample of LaBS glass with a target chemical composition (wt %): 9.0 Al2O3, 11.8 B2O3, 12.2 Gd2O3, 6.3 HfO2, 17.2 La2O3, 13.6 Nd2O3, 9.5 PuO2, 18.1 SiO2, 2.3 SrO was prepared from PuO2 powder and mechanically activated mixture of chemicals at 1500 °C. The obtained product was visually homogeneous. Xraydiffraction of the as-prepared glass showed that it mostly consists of a vitreous phase withsmall amounts of crystalline PuO2 (or PuO2-HfO2 solid solution with minor HfO2), britholite andan oxide with a fluorite structure and a composition close to GdHfO1.75. The crystalline fractionincreased after storage for ∼1 year. Magnitude of the FT of EXAFS spectrum at Pu LIII edgeshows that the peak due to first coordination sphere is much more intense than that of the secondshell. This indicates that though some Pu entered crystalline phases (mainly distorted PuO2), itsmajor fraction remained in the vitreous phase. Fit of the spectrum (R-factor = 0.02) gives thefollowing distances: R (Pu-O1)1 = 1.98 (σ = 0.04), R (Pu-O1)2 = 2.18 (σ = 0.04), R (Pu-O1)3= 2.35, R (Pu-Pu) = 3.72 (σ = 0.04), R (Pu-O2) = 4.4 (σ = 0.06). Oxygen environment ofthe Pu4+ ions in the vitreous phase resembles axially squeezed tetragonal pyramid with acoordination number ∼5. The distances ∼2.35 and ∼4.4 correspond to the pairs Pu-O in thefirst and the second shells in the crystalline PuO2. The distance ∼3.72 corresponds to the Pu-Pu and/or Pu-M (M = Ln, Hf) distances. EXAFS spectra of Hf show that Hf is present mostly in thevitreous phase with major neighbors at 2.17 and ∼3.2 A.
Initial Investigation Into the Vitrification of High Molybdenum Solids in Borosilicate Glass
Authors: Dunnett Barbara F. , Gribble Nick R. , Riley Andrew D. , Steele Carl J. 
Published: April 2011

AbstractSellafield Ltd operates a Waste Vitrification Plant (WVP) to immobilise the arisings from the reprocessing of spent nuclear fuel. Washout of solids from the base of waste storage tanks in preparation for decommissioning is likely to produce feeds enriched in molybdenum to the WVP. Vitrification of such feeds in the borosilicate glass formulation currently used by the WVP for vitrification of reprocessing waste has been investigated to determine the maximum achievable loading of MoO3.The vitrification of molybdenum in the absence and presence of reprocessing waste was studied. A number of glasses were manufactured in the laboratory containing various waste loadings. The resultant glasses were examined both visually and under the scanning electron microscope for the presence of any phase separation. Additional aluminium was added to the glasses manufactured in the absence of reprocessing waste to improve the durability of the glass. In borosilicate glass containing 3.5 wt% Al2O3 the onset of a molybdenum phase separation was observed in glasses containing 2.6 wt% MoO3. In the presence of Magnox reprocessing waste, phase separation was observed when the product contained >3.8 wt% MoO3. Soxhlet durability testing of a selection of the glasses manufactured was carried out. The Soxhlet durability of glasses in the absence of phase separation was good.
Corrosion Behavior of Simulated LLW Glass in Deionized Water
Authors: Maeda Toshikatsu , Yamaguchi Tetsuji , Hotta Katsutoshi , Mizuno Tsuyoshi , Banba Tsunetaka 
Published: April 2011

AbstractStatic leach tests were conducted for simulated low-level radioactive waste (LLW) glass in deionized water at 90 °C for up to one year to investigate the dissolution mechanism of LLW glass. Widely studied leaching behavior of high-level radioactive waste (HLW) glass is referred in discussing the dissolution mechanism. LLW glass is characterized by higher sodium (Na) and aluminum (Al) contents than HLW glass, about twice as high as R7T7, with its SiO2 content close to HLW glass. Powdered simulated LLW glass of three different chemical compositions was tested with the glass-surface-to-water-volume ratio of 2,000 m−1. The release rates of boron (B), widely used as an indicator of dissolution for HLW glass, decreased with time during leaching, as commonly observed in similar tests for HLW glass. The pH of the leachate was stable around 11.3 - 11.6, which is higher than those in similar tests for HLW glass by one pH unit or more. The concentrations of Al in the leachates were higher compared to data for HLW glass by two orders of magnitude. The high concentration seems to be caused by higher pH. In the leachate condition of the present tests, a zeolitic mineral (analcime) is thermodynamically more stable than amorphous silica (SiO2(am)) which is known to control the concentration of dissolved silica (Si) with respect to HLW glass. The present results imply that dissolution of the LLW glass is accompanied with formation of analcime under virtually closed systems such as geological repository where the groundwater flow rate is quite low.
Phase Formation in the Vitrification of Savannah River Site SB4 HLW Sludge Surrogate Using Frit and Glass Forming Chemicals
Authors: Stefanovsky O.I. , Stefanovsky S.V. , Akatov A.A. , Marra J.C. 
Published: April 2011

AbstractPhase formation mechanisms associated with the vitrification of Savannah River Site (SRS) Sludge Batch 4 (SB4) high level waste surrogate with high iron and aluminum contents were studied by infrared spectroscopy (IRS), X-ray diffraction (XRD) and optical microscopy. Two mixtures at 50 wt.% SB4 waste loading were prepared as slurries with a water content of ∼50 wt% using a waste surrogate and commercially available Frit 503-R4 (Li2O – 8 wt%, B2O3 – 16 wt%, SiO2 – 76 wt%) or mixture of chemicals (LiOH·H2O, H3BO3, SiO2). The mixtures were air-dried at a temperature of 115 °C and heat-treated at 500, 700, 900, 1000, 1100, 1200, and 1300 °C for 1 hr at each temperature. IR spectra and XRD patterns of the products heat-treated at each temperature were recorded. In both the mixtures phase formation reactions started at low temperatures and yielded intermediate phases (sodalite, pyroxene-type, nepheline), and the reactions were mostly completed within the temperature range between 1000 and 1100 °C. The glassy materials prepared at 1200 and 1300 °C were composed of vitreous phase and magnetite/trevorite type spinel.
Application of Track Membranes for Additional Treatment of Water Coolant of Nuclear Reactor
Authors: U.S. Salihbaev , A.A. Kist , R. Malikov Sh. , V.P. Pikul , R.I. Radyuk , G.A. Radyuk , E.A. Danilova , N.M. Muhamedshina 
Published: April 2011

AbstractExperiments on determination of operational effectiveness of track membranes with different diameter of pores (0.2 – 0.05 microns) for additional purification of water of the first contour of the reactor before ion-exchange resins were carried out. The track membranes detain products of corrosion, and also products of wearing of moving parts of the equipment by the size of > 0.05 microns. Filtration experiments on of water of the first contour of the exploratory reactor of VVR-SM have shown high performance of track membranes.