bluuebunny/crossref_metadata_2025 huggingface dataset:
The Scintillation Mechanism In Gd Based Crystals Doped With Re 3+ Ions.
Authors: Kondratiev D.M. , Korzhik M.V. , Pavlenko V.B.
Published: April 2011

The mechanism of scintillations in crystals on the base of Gd3+ - Ce3+ transfer have been developed.
Optical Properties and Radiation Damages of Cerium Fluoride Crystals Doped with Alkali-Earth and Rare-Earth Elements.
Authors: Gusev Yu.I. , Melchakov E.N. , Mironov I.A. , Panteleev L.A. , Reiterov V.M. , Rodnyi P.A. , Seliverstov D.M. , Shchetkowsky A.I. , Yazikov D.M. , Zakharov N.G.
Published: April 2011

Study of optical properties and radiation damages of Cerium Fluoride crystals doped with Ca, Ba, Sr, La, Nd, Zr and Hf in the wide range of concentrations has been performed withthe goal to obtain high optical transparency of crystals at different cumulative doses under γ-irradiation. Time decay curves and relative light yields of scintillators asa function of doping level were measured using X-ray excitation of samples and single photon counting method.
Study of neutron damage resistance of some scintillating crystals and associated photodetectors with the nuclear reactor ULYSSE
Authors: Chipaux R. , Faure J.-L. , Pansart J.-P. , Poinsignon J. , Rebourgeard P. , Tartas J. , Dauphin France G. , Safieh J.
Published: April 2011

Radiation resistance is a mandatory requirement for a major part of the active or passivecomponents of the particle detectors planned for the future high energy accelerator LHC.

Ulysse is a training reactor of the Institut National des Sciences et Techniques Nucl éaires (INSTN), in Saclay, and a very suitable tool for testing materials and devicesfor these future large detectors. Its radiation spectrum characteristics are very similarto those expected in these detectors, in terms of spectra of fast neutrons, thermal neutrons and gamma photons, and ratios between those types of radiation.

Results are presented on the neutron resistance of two scintillating crystals, candidatesfor electromagnetic calorimetry, cerium fluoride (CeF3) and lead tungstate (PbWO4), and on the behaviour under neutron irradiation of some avalanche photodiodes, currently under development for light detection of these crystals.
PROGRESS ON SCINTILLATOR RESEARCH BY THE CRYSTAL CLEAR COLLABORATION
Authors: Lecoq Paul
Published: April 2011

A large effort has been undertaken since nearly 2 years by 14 research institutes (the “Crystal Clear” collaboration, CERN RD project 18), in order to develop and investigate new dense, radiation hard and fast inorganic scintillators suitable for very good resolution electromagnetic calorimeters to be built at the new high luminosity accelerators. Other fields of interest like nuclear physics, gamma ray astronomy, medical imaging (PET), safety systems and non destructive industrial applications are also rapidly growing. Progress on cerium fluoride will be reviewed with some comments about mass scale production and cost considerations. The pro's and con's of potentially cheaper solutions based on fluoride glasses or lead compounds will be discussed. Finally some attractive candidates will be mentioned for low energy gamma ray applications.
The Chemistry Of Two-Component Fluoride Crystalline Optical Media For Heavy, Fast, Radiation Hard Scintillators
Authors: Sobolev B.P. , Krivandina E.A. , Fedorov P.P. , Vasilchenko V.G.
Published: April 2011

Prospects for preparation of two-component dense optical materials for scintillators are shown, using data on phase diagrams of about 300 MFm - RFn (m, n ≤ 4) type systems, formed by metal fluorides. Primary characteristics (decay time and light output of luminescence, radiation hardness, etc.) of some multicomponent crystals are reported.
Photoluminescence Of Zincselenide Single Crystals Annealed In Zinc Or Selenium Atmosphere
Authors: Yoshino Kenji , Matsushima Yasushi , Kinoshita Hiroyoshi , Hiramatsu Makoto
Published: April 2011

Zincselenide single crystals grown by the sublimation method are annealed in Zn or Se atmosphere. The annealing effects are examined by means of photoluminescence (PL) and reflection spectroscopy at 4.2 K. In the PL spectrum for the as-grown crystal, bound exciton lines (I2, I1) are observed. For the Zn-annealed crystal, the free exciton line is clearly observed. For the Se-annealed crystal, peak positions of all lines shift to the higher energies and all lines become sharp, compared with the spectra for the as-grown crystal. It is concluded that Sc-vacancies affect the bandgap energy more than Zn-vacancies do.
Deformation Welding Of Scintillating Materials
Authors: Bazhenov A.V. , Egorov V.K. , Gasparov L.V. , Klassen N.V. , Mahonin S.I. , Shmurak S.Z. , Shmyt'Ko I.M.
Published: April 2011

Experiments on connecting scintillating crystals to form homogeneous pieces by means of plastical deformation are described. Optical transmission, radiation hardness, and scintillation spectra have been used for the evaluation of the quality of the bond. The results of experiments on fluorides of cerium, barium, and lead; and cesium iodide confirm that deformation welding can be used successfully for economic manufacturing of large homogeneous scintillators from several smaller parts.
Thermal Misfit and Thermal Fatigue Induced Damage in Brittle Composites
Authors: Sridhar N. , Rickman J. M. , Srolovitz D. J.
Published: April 2011

We examine the conditions under which differences in thermal expansion between a particle and the matrix leads to crack growth within the matrix. Using linear elastic fracture mechanics, we obtain closed-form, analytical results for the case of a penny shaped crack present in the matrix interacting with a spherical inclusion which is misfitting with respect to the matrix. A simple and direct relationship is established between the strain energy release rate, the crack size, the crack orientation with respect to the inclusion, the crack/inclusion separation, the degree of thermal expansion mismatch and the elastic properties of the medium. We also analyze the size to which these cracks can grow and find that for a given misfit strain and material properties, crack growth is inhibited beyond a certain critical crack size. Finally, the preferred orientation of these cracks as a function of misfit strain is predicted. The implication of these results for thermal cycling are analyzed.
Issues in Potential IMC Application for Aerospace Structures
Authors: Ward Charles H. , Culbertson Andrew S.
Published: April 2011

Intermetallic-matrix composites (IMCs) are intended for applications involving higher temperatures and stresses than conventional metallic matrix composites. Consequently, environmental effects, thermo-mechanical fatigue, interfacial thermodynamic stability, creep resistance, processing and cost are only a few of the obstacles to introduction in real products. The primary goal of current IMC development efforts is to provide ‘revolutionary’ materials for components that are enabling technologies in advanced demonstrator gas turbine engines. As compared to production applications, the hurdles for entry into demonstrator engine programs are not as high due to the limited operating time and the small number of parts to be produced. This paper examines the barriers to the introduction of IMCs in the context of application to production aerospace structures.
Numerical Simulations of Creep in Ductile-Phase Toughened Intermetallic Matrix Composites
Authors: Henshall Gregory A. , Strum Michael J.
Published: April 2011

Analytical and finite element method (FEM) simulations of creep in idealized ductilephase toughened intermetallic composites are described. For these strong-matrix materials, the two types of analyses predict similar time-independent composite creep rates if each phase individually exhibits only steady-state creep. The composite creep rate increases above that of the monolithic intermetallic with increases in the stress exponent of the intermetallic, the volume fraction of the ductile phase, and the creep rate of the ductile phase. FEM analysis shows that the shape of the ductile phase does not affect the creep rate but may affect the internal stress and strain distributions, and thus damage accumulation rates. If primary creep occurs in one or both of the individual phases, the composite also exhibits primary creep. In this case, there can be significant deviations in the creep curves computed by the analytical and FEM models. The model predictions are compared with data for the Nb5Si3/Nb system.
Nanocomposites Containing Nanoclusters of Metals or Semiconductors
Authors: Burnam Kimberly J. , Carpenter Joseph P. , Lukehart Charles M. , Milne Stephen B. , Stock S. R. , Glosser R. , Jones Bobby D.
Published: April 2011

Neutral, low-valent complexes of transition metals or an organometallic compound of Ge are prepared containing ancillary ligands which bear silicate ester or (alkoxy)silicon functional groups. Inclusion of these molecules as dopant species in a conventional sol-gel synthesis of silica xerogels affords silica xerogels in which dopant molecules have presumably been covalently incorporated into the xerogel matrix with uniform and high dispersion. Subsequent thermal treatment of these molecularly doped xerogels under reducing or oxidizing/reducing conditions gives nanocomposites containing nanoclusters of metals or semiconductor substances. By this procedure, nanocomposites containing nanoclusters of Ag, Cu, Pt, Os, CCo3, Fe2P, Ni2P, or Ge have been prepared. Preliminary evidence for the formation of a nanocomposite containing Pt-Sn nanoclusters derived from a bimetallic molecular precursor is also presented. Characterization data for the nanocomposite materials include TEM, electron diffraction, EDS, XRD, and selected use of micro-Raman spectroscopy. These results support the hypothesis that covalent incorporation of molecular precursors containing low-valent metals into a silica xerogel can afford nanocluster phases with high dispersion, relatively small particle size, and unusual elemental composition.
Synthesis of Low Density Microcellular Activated Carbon Supported Nanophase Pt and Pd Particles and Study of Its Catalytic Properties
Authors: Lin Hong-Ming , Huang Ching-Shung , Hsu Chi-Ming
Published: April 2011

The use of activated low density microcellular carbon (LDMC) as a catalysis supporter for nanophase Pt or Pd particles has been successfully developed in this study. The good dispersion and interfacial properties of nanophase Pt or Pd particles on activated LDMC are formed by using an impregnation and sintering process. The interfacial structures are examined by TEM, HRTEM and an image analyst system. No preferred orientation of interfacial bonding has been found between nanophase Pt and activated LDMC. The activated LDMC supported Pt or Pd catalysts have the high reactivity which can complete hydrogenation and oxidation of CO gas at low temperatures (<453 K). The catalytic activity of CO hydrogenation is increased as the size of the nanophase Pt and Pd particles decreases.
Catalytic Properties of Nanocrystalline WO3−X, Pt/WO3−X and Pd/WO3−X Particles
Authors: Tung Chiun-Yen , Lin Hong-Ming , Hsu Chi-Ming , Yang Chao-Cheng
Published: April 2011

The gas-condensation technique is used to produce the nanocrystalline WO3−C, Pt/WO3−X and Pd/WO3−X powders under different atmospheres and pressures. High resolution electron microscope shows there exists well bonded interface between Pt or Pd and WO3−X The WO3−X, Pt/WO3−X and Pd/WO3−x nanocrystals grow into needle shape with plate inside when these asevaporated powders are compacted and sintered at 900 °C for two hours. The plate grows preferentially in {220) plane along < 001 > direction. However, the mean particle size of nanophase Pt and Pd only increases from less than 10 nm to 30 nm and 50 nm, respectively. The gas chromatography results show that nanophase Pt/VO3−X powders have better catalytic effects in converting CO to CO2 than nanophase WO3−X and Pd/WO3−X powders.
Subwavelength Localization of Optical Modes in Fractals
Authors: Shalaev Vladimir , Botet R. , Moskovits M.
Published: April 2011

Resonant optical excitation of fractal clusters generates dipolar eigenmodes which are extremely localized within areas much smaller than the wavelength. The localization occurs due to the fractal morphology and accounts for the very high local fields leading to the huge enhancement of various optical effects. In particular, Rayleigh and Raman light scattering and, especially, nonlinear optical processes, such as 2-photon photoemission and degenerate four-wave mixing, are strongly enhanced in fractal clusters. The spatial distribution of the modes shows the frequency and polarization selectivity.
Aluminophosphate Glasses with High Sulfate Content
Authors: Stefanovsky Sergey V. , Ivanov Igor A. , Gulin Anatolii N.
Published: April 2011

To immobilize a high sulfate radioactive wastes a system Na2O-A12O3-P2O5-SO3 has been chosen as one where glasses have a relatively low melting points and good chemical durability. Glasses within partial system 44 Na2O, 20 A12O3 (36-x) P2O5 x SO3 have been prepared at 1000 °C. A possibility of assimilation up to 12 mole % of SO3 has been established. The basic properties of sulfate-containing glasses as density, microhardness, thermal expansion coefficient, transformation and deformation temperatures, viscosity, electric resistivity, leach rate of ions and diffusion coefficients of 22Na, 35S, 90Sr and 137Cs have been measured. Glass structure by infrared and EPR spectroscopies has been investigated.
Sorption of60Co,85Sr,137Cs,237Np and241Am on Soil Under Coexistence of Humic Acid: Effects of Molecular Size of Humic Acid
Authors: Tanaka Tadao , Senoo Muneaki
Published: April 2011

Sorption experiments have been performed by a batch method, to study the effects of humic acid of different molecular size on the complexing stability with60Co,85Sr,137Cs,237Np and241Am, and on the sorption behavior of these radionuclides on a sandy soil.

Equilibrium constantsKin the sorption of137Cs and237Np onto the soil were not changed at different concentrations of humic acid since137Cs and237Np do not interact with humic acid, while those of60Co and241Am decreased with increasing humic acid concentration due to forming humic complexes. However, theKof85Sr was not changed at different humic acid concentrations, despite85Sr interacts with humic acid. This contradiction was probably caused from that a main binding of85Sr with humic acid is not based on coordination bond but electrostatic force, due to relatively high concentration of non–radioactive strontium. The theoretical sorption model taking account of the interaction of60Co and241Am with humic acid could well reproduce the values ofKfor each radionuclide at different concentrations of humic acid.

Concentration profiles of the radionuclides in each size fraction of the solution before and after the sorption experiments were examined by ultrafiltration technique. The reduction of concentration of60Co in the fraction less than 300,000 of cutoff molecular weight (MW) and that of concentration of241Am in the fraction larger than 100,000MW, respectively, by the sorption onto the soil decreased with increasing humic acid concentration. This decrease resulted in the decrease in theKof60Co and241Am with increasing humic acid concentration.
Modeling of Yb(III) Sorption on Kaolinite by Using Single Oxide Surface Complexation Models
Authors: Marmier Nicolas , Dumonceau Jacques , Chupeau Joël , Fromage Francine
Published: April 2011

Surface complexation model was used to describe ytterbium sorption on kaolinite using surface acidity constants and surface complexation constants determined on alumina and silica.
Uranium(IV) Solubility and Hydrolysis Constants Under Reduced Conditions
Authors: Yajima Tatsuya , Kawamura Yuji , Ueta Shinzo
Published: April 2011

The solubility of UO2 (s) was examined in dilute NaCl solutions at room temperature and in the pH range from 2 to 12. Dissolution equilibrium showed good agreements between the data obtained by oversaturation and undersaturation experiments.

The dissolution reactions that control the solubility of U[IV] are estimated as UO2 (s) + 4H+ → U4+ + 2H2O and UO2 (s) + 2H2O → U(OH)4°. The log K at zero ionic strength are yielded 0.34 ± 0.4 and −8.7 ± 0. 4, respectively. The hydrolysis constant (log β14) is calculated −9.0 ± 0.5 for the hydrolysis reaction of U4+ + 4H2) → U(OH)4° + 4H+. Contribution of the other uranium species to the solubility are of minor importance.

The crystallization of the precipitations of U02 (s) progressed gradually in the oversaturation experiments. Nevertheless the progress of crystallization had little effect on the solubility.
The Identification and Degradation of Isosaccharinic Acid, a Cellulose Degradation Product
Authors: Greenfield B. F. , Holtom G. J. , Hurdus M. H. , O’Kelly N. , Pilkington N.J. , Rosevear A. , Spindler M. W. , Williams S. J.
Published: April 2011

Nirex is seeking to develop a deep underground repository for the disposal of solid intermediate-level and low-level radioactive wastes (ILW and LLW) in the UK. One possible influence on the behaviour of radionuclides is the formation of water-soluble complexants by the degradation of the solid organic polymers that will be present in the wastes. The degradation products of cellulose have been shown to increase the solubility of plutonium and other radionuclides and to reduce sorption onto near-field and far-field materials. Degradation of cellulose under anaerobic alkaline conditions produces a range of organic acids. In this paper 2-C-(hydroxymethyl)-3-deoxy-D-pentonic acid (isosaccharinic acid, ISA) is identified by High Performance Liquid Chromatography as a significant component of cellulose leachates. A combination of fractionation of cellulose leachates and plutonium solubility determinations shows that ISA is responsible for the majority of the enhancement of plutonium solubility observed in such leachates. Further degradation of ISA by chemical or microbial action may lessen the effect of degraded cellulose leachates. Experimental studies on the chemical degradation of this compound under alkaline conditions suggest that the presence of oxygen is required. Microbial degradation studies show that the plutonium solubility in solutions of ISA is reduced by their exposure to microbial action.
Corrosion Behavior of a Powdered Simulated Nuclear Waste Glass Under Anoxic Condition
Authors: Inagaki Y. , Furuya H. , Idemitsu K. , Maeda T. , Sakai A. , Banba T. , Muraoka S.
Published: April 2011

Static corrosion tests were carried out with a powdered simulated waste glass in deionized water at 90 °C under oxic and anoxic conditions, respectively. The corrosion tests under anoxic condition were performed in a globe box purged with mixed gas (N2+5%H2), where the pH and Eh of deionized water were maintained at 6.9 and −0.35 V vs.S.H.E. at 25 °C, respectively.

It was observed that there is a little difference between NL values under oxic and anoxic conditions. For soluble elements (Li, B, Na, Mo) and Ca, NL values under anoxic condition were slightly smaller than those under oxic condition. For Fe and Al, NL values under anoxic condition were slightly larger than those under oxic condition. For Si, Ce, La and Nd, there was no difference between NL values under oxic and anoxic conditions. The experimental results were analyzed on the basis of a corrosion model (Diffusion-combined Model), in which the solution concentration of elements associated with solution pH and Eh can be derived thermodynamically by use of PHREEQE. The analysis suggests that precipitating minerals controlling the solution concentrations of Fe and Ca under anoxic condition are different from those under oxic condition.
Modeling of Solution Renewal with the Kindis Code: Example of R7T7 Glass Dissolution at 90°C
Authors: Advocat T. , Crovisier J. L. , Clement A. , Gerard F. , Vernaz E.
Published: April 2011

The deep underground environment that would correspond to a geological repository is a system open to fluid flow. It is therefore necessary to investigate the effects of solution renewal on the long-term behavior of glass in contact with water. These effects can now be simulated using the new version of the geochemical Kindis model (thermodynamic and kinetic model).We tested the model at 90°C with an SAIV ratio of 400 m−1 at twelve renewal rates of pure water ranging from 200 to 0 vol% per day. With renewal rates between 200 and 0.065 vol% per day, steady-state conditions were obtained in the reaction system: i.e. the glass corrosion rate remained constant as did the concentrations of the dissolved species in solution (although at different values depending on the renewal rate). The ionic strength never exceeded 1 (the validity limit for the Debye-Huckel law) and long term predictions of the dissolved glass mass, the solution composition and the potential secondary mineral sequence are possible. For simulated renewal rates of less than 0.065 vol% per day (27 vol% per year), the ionic strength rose above 1 (as in a closed system) before steady-state conditions were reached, making it critical to calculate long-term rates; A constant and empirical long-term rate, derived from laboratory measurement, have to be extrapolated. These calculations were based on a first order equation to describe the glass dissolution kinetics. The results obtained with the KINDIS code show discrepancies with some major experimental kinetic data (the long term rate must decrease with the « glass-water » reaction progress, under silica saturation conditions). This clearly indicates that a more refine kinetic relation is needed for the glass matrix.
Preliminary Test on Gas Migration Through Bentonite-Sand Mixture
Authors: Hokari T. , Ishii T. , Nagasawa T. , Tomita R. , Nakajima M.
Published: April 2011

The Low-Level Radioactive Disposal facility [1] is planned to cover the vaults with impermeable bentonite-sand mixture in order to minimize groundwater flux through the facility. In case that metal wastes are to be disposed of in the burial facility in the future, it is essential to confirm that bentonite mixture should have gas permeability enough for the gas volume which would be expected to be generated due to an aerobic corrosion of metals[2].
This report performed a preliminary test with a bentonite-sand mixture whose aggregate was Japanese Standard sand. Results are the followings;(l)Gas breakthrough pressure of the mixture was less than the overburden pressure. The gas permeability was estimated to be of order of 10-2 md. (2)The mixture did not deteriorate in hydraulic conductivity after gas breakthrough.
Radionuclide Retardation in Crystalline Rock Fractures.
Authors: HÖlttÄ P. , Hakanen M. , Siitari-Kauppi M. , HautojÄrvi A.
Published: April 2011

Transport and retardation of slightly sorbing sodium was studied in Syyry area SY-KR7 mica gneiss and in altered porous tonalite. Experiments were performed using dynamic fracture and crushed rock column methods and the static batch method. Flow conditions in the columns were determined using tritiated water and chloride as non-sorbing tracers. 14C-PMMA method was used to study the pore structure of matrices and the surface areas were determined by B.E.T. method. Sodium was retarded strongly in altered tonalite owing to homogeneously porous matrix structure and the composition of alteration minerals. An agreement between retardation values in batch and crushed rock column experiments as well as in fracture column experiments was good.
Comparison of the Concepts and Assumptions in Five Recent HLW/Spent Fuel Performance Assessments
Authors: Neall F. B. , Baertschi P. , McKinley I.G. , Smith P. A. , Sumerling T. , Umeki H.
Published: April 2011

Integrated performance assessments of proposed repositories for HLW involve multidisciplinary studies which include identification of possible paths of future evolution of the repository system (scenario analysis) and quantification of the consequences of each scenario using deterministic or probabilistic modelling approaches. The results of such studies are commonly presented as estimates of consequence (e.g. dose to a representative individual) against time which extends into the distant future. Individual components of the model chains used can be tested to some extent, but how can the integrated assessment be evaluated to give additional confidence in the overall results? In order to address this issue, the Kristallin-l performance assessmentI has been compared with other HLW/spent fuel performance assessments. This technical comparison forms the basis of this paper which summarises the results from a more extensive comparison of a number of HLW/spent fuel disposal concepts, safety assessment methodologies and models2. It is part of a wider study which attempted to put the results of the Kristallin-I performance assessment into perspective by use of both this technical comparison with other performance assessments and by consideration of other information (e.g. natural analogue studies, environmental radiation data and risk assessments for radiological and non-radiological hazards) which allows the reasonableness of the results and significance of the predicted doses to be illustrated. Due to limitations of space, this aspect of the study has not been included here and the reader is referred to the “Kristallin-I: Results in Perspective” report2 for more details.
Mechanism of Unirradiated UO2 (S) Dissolution in Nacl and Mgcl2 Brines at 25°C
Authors: de Pablo Joan , Giménez J. , Torrero M. E. , Casas I.
Published: April 2011

The dissolution of unirradiated UO2 (s) has been studied in NaCl and MgCl2 brines under both reducing and oxidizing conditions.

The initial uranium release under reducing conditions has been attributed to the dissolution of an initial oxidized layer. The final uranium concentrations have been modeled by using the PHRQPITZ computer program giving the solubility of the solid phase UO2 (s).

Under oxidizing conditions, the initial release is the sum of the oxidized layer dissolution and the oxidation/dissolution of the UO2. The release rates calculated are 1.4·10−5 mol d−1 m−2 in NaCl2-brine and 3.6·10−5 mol d−1 m−2 in MgCl2-brine. After the initial release, uranium concentration in the NaCI-brine reaches a constant value, which has been attributed to the formation of a secondary solid phase. In MgCl2-brine, the uranium concentration increases slowly indicating, in this case, no control by secondary phase formation.
Simulation of The State of Carbon Steel n Years After Disposal with n Years of Corrosion Product on its Surface in a Bentonite Environment
Authors: Kojima Yoichi , Hioki Toshinobu , Tsujikawa Shigeo
Published: April 2011

The use of bentonite as buffer and carbon steel as overpack material for the geological disposal of nuclear waste is under investigation. To better assess the long term integrity of the carbon steel overpack, a quantitative analysis of the corrosion behavior on the steel surface for time frames beyond that of feasible empirical determination is required. The state n years after disposal, consisting of Carbon Steel / Corrosion Products + Bentonite / Water, was simulated and the corrosion behavior of the carbon steel in this state investigated. The following facts became apparent. Both the corrosion rate and the non-uniformity of it increased with increase in the corrosion product content in the compacted bentonite. When the corrosion product layer was formed between the carbon steel and the bentonite, it ennobled the corrosion potential and increased the corrosion rate.
Zirconolite-Rich Ceramics for Actinide Wastes
Authors: Vance Eric R , Begg B. D. , Day R. A. , Ball C. J.
Published: April 2011

New X-ray diffraction and scanning electron microscopy data are given for the incorporation of Np and Pu in zirconolite, at levels of tens of percent. The actinide valences and the cations they replace are deduced from the microanalysis of the zirconolite compositions, and X-ray absorption data are used to obtain more direct information on the valences of Ce and Nd, which are used as simulants of Pu and trivalent actinides respectively. Trivalent rare earths and actinides have extensive solid solubility in zirconolite, mainly but not exclusively in the Ca site. Tetravalent rare earths and actinides have considerable solid solubility in the Zr site of zirconolite, and some solubility in the Ca site, but the strong tendency of zirconolite with ions substituted in the Zr site to undergo phase separation complicates structural interpretation. In zirconolite-rich Synroc-type ceramics designed to immobilise waste actinides, the target actinide waste loading has been set at 20 wt% and early leach results indicate the durability is at least as good as that of Synroc-C.
Synroc for Immobilising Excess Weapons Plutonium
Authors: Jostsons A. , Vance E. R. , Mercer D. J. , Oversby V. M.
Published: April 2011

The immobilisation of excess weapons plutonium into Synroc can meet all of the important criteria discussed by the U.S. National Academy of Sciences (NAS)(1)for disposal, if the disposal option is pursued rather than options that exploit the energy value of plutonium. This paper summarises the relevant background of Pu incorporation into Synroc, the durability of Pu-containing Synroc and outlines a process flowsheet based on the experience with the 10 kg/hr Synroc Demonstration Plant at ANSTO. The extensive solid solubility of Pu in Synroc, coupled with a very high degree of chemical durability under hydrothermal conditions, makes Synroc ideal as a waste matrix for Pu disposal in deep boreholes to minimise diversion and proliferation risks.
Hydrothermal Synthesis of Hydroxyapatite and Pollucite from Calcium Phosphate
Authors: Kaneko Masaaki , Shoji Yuichi , Matsuura Hiroyuki , Yamasaki Nakamichi
Published: April 2011

Hydroxyapatite (HAP : Ca10(PO4 ) 6 (OH) 2 ) and aluminosili-cate were easily synthesized using a hydrothermal process with mixing ratios of Ca/P=1.67 (Ca(PO3)2 and Ca(OH)2) and Si/Al=4 (SiO2 and Al(OH)3). The temperature was kept constant at 573 K for 60 minutes. .Cesium (Cs) and Cerium (Ce) contained in Ca(PO3)2 , were found to take on a stable form in the pollucite (CsAlSi2O6) structure and the monazite (CePO4) structure.
Integrated Approach to Modeling Long-Term Durability of Concrete Engineered Barriers in Llrw Disposal Facility
Authors: Lee J. H. , Roy D. M. , Mann B. , Stahl D.
Published: April 2011

This paper describes an integrated approach to developing a predictive computer model for long-term performance of concrete engineered barriers utilized in LLRW and ILRW disposal facilities. The model development concept consists of three major modeling schemes: hydration modeling of the binder phase, pore solution speciation, and transport modeling in the concrete barrier and service environment. Although still in its inception, the model development approach demonstrated that the chemical and physical properties of complex cementitious materials and their interactions with service environments can be described quantitatively.

Applying the integrated model development approach to modeling alkali (Na and K) leaching from a concrete pad barrier in an above-grade tumulus disposal unit, it is predicted that, in a near-surface land disposal facility where water infiltration through the facility is normally minimal, the alkalis control the pore solution pH of the concrete barriers for much longer than most previous concrete barrier degradation studies assumed. The results also imply that a highly alkaline condition created by the alkali leaching will result in alteration of the soil mineralogy in the vicinity of the disposal facility.
Gas Transportation in Saturated Cementitious Materials
Authors: Iriya K. , Hironaga M. , Kawanishi M.
Published: April 2011

Radioactive waste repositories are constructed underground below ground water level. Main engineered barrier of the repository consists of structural walls, backfill mortar, and consolidated wastes. Cementitious materials are mainly adopted for the engineered barrier. Gas (hydrogen or methane) generation due to corrosion and microbial degradation is predicted, since the waste consists of metals like steel and organic material. It is important issue to define gas transport mechanism in cementitious materials in order to assess the gas release influence on the engineered barrier and pressure rise in the repository. Although cementitious materials have enough permeability to transport gas in dry condition, it is expected to be impermeable or so in saturated condition, in which repository is placed. In this paper, water and gas permeability both in dry and saturated conditions are investigated. The pressure in the vault, and gas transport mechanism is predicted. Certain threshold pressure exists, and it can be recognized that gas permeability is dependent on water saturation degree at a pressure greater than the threshold pressure. Loading pressure of 0.7 MN / m2 is needed for the flow of gas in saturated concrete. Intrinsic gas permeability of 6.5 × 10−19 m2 is obtained, which is very small value to keep the low pressure inside the vault. Consequently, it is predicted that gas cannot be transported through the intact concrete, however, it can be transported through defective zone which is developed during construction, and so on.
Sorption of Plutonium and Americium on Repository, Backfill and Geological Materials Relevant to The JNFL Low-Level Radioactive Waste Repository at Rokkasho-Mura
Authors: Baston G M N , Berry J A , Brownsword M , Heath T G , Tweed C J , Williams S J
Published: April 2011

An integrated programme of batch sorption experiments and mathematical modelling has been carried out to study the sorption of plutonium and americium on a series of repository, backfill and geological materials relevant to the JNFL low-level radioactive waste repository at Rokkasho-Mura.

The sorption of plutonium and americium on samples of concrete, mortar, sand/bentonite, tuff, sandstone and cover soil has been investigated. In addition, specimens of bitumen, cation and anion exchange resins, and polyester were chemically degraded. The resulting degradation product solutions, alongside solutions of humic and iso-saccharinic acids were used to study the effects on plutonium sorption onto concrete, sand/bentonite and sandstone.

The sorption behaviour of plutonium and americium has been modelled using the geochemical speciation program HARPHRQ in conjunction with the HATCHES database.
The Sorption of Uranium and Technetium on Bentonite, Tuff and Granodiorite
Authors: Baston G. M. N. , Berry J. A. , Brownsword M. , Cowper M. M. , Heath T. G. , Tweed C. J.
Published: April 2011

A combined experimental and modelling study of the sorption of uranium and technetium on geological materials has been carried out as part of the PNC programme to increase confidence in the performance assessment for a high-level radioactive waste (HLW) repository in Japan. Batch sorption experiments have been performed in order to study the sorption of uranium and technetium onto bentonite, tuff and granodiorite from both equilibrated seawater and de-ionised water under strongly-reducing and non-reducing conditions.

A preliminary study of the sorption of uranium on mineral surfaces in granodiorite has also been undertaken using a nuclear microprobe.

Mathematical modelling using the geochemical speciation program HARPHRQ in conjunction with the HATCHES database has been carried out in order to interpret the results of the sorption experiments.
Applications of MeV Ion Implantation in Semiconductor Device Manufacturing
Authors: Borland John O.
Published: April 2011

Use of MeV ion implantation for mass production of CMOS devices at 0.5um design rule and beyond is now being accepted around the world for 16Mb DRAM, 16Mb Flash memory and CMOS logic/microprocessor technologies. Incorporating MeV well formation for twin well and triple well results in a reduction of up to 3 masking layers corresponding to process simplification and manufacturing cost reduction of 10% to 16%. For CMOS logic application, a new structure called BILLI (Buriedjmplanted Layer for Lateral Isolation) is showing great promise for latch-up free CMOS and when combined with hydrogen denuded bulk Czochraliski (CZ) grown silicon wafers, has the potential to replace epitaxial wafers with improved device performance. This paper will review MeV ion implantation use for these various CMOS applications.
Luminescence During Tb-Ion Implantation into Sapphire
Authors: Kumagai Makoto , Iwaki Masaya
Published: April 2011

A study has been made of the luminescence during Tb-ion implantation in Al2O3 or by Ar- or He-ions bombardment to Tb-ion implanted Al2O3. The substrates used were colorless and transparent single crystal ɑ-Al2O3 with (0001) or (1102) surface orientation. Ion implantations of Tb-ions in Al2O3 were carried out at fluences of 1x1013 to 1x1017 Tb/cm2 at 100 keV at nearly room temperature. Change in color of Al2O3, substrates by Tb implantation was invisible to the naked eye. The luminescence spectra were measured by Ar (100 keV) or He (50 keV) bombardment to Tb implanted Al2O3 or during Tb implantation into Al2O3 using a spectroscopy with three optical filters and photomultiplier. The luminescence spectra during Tb implantation into AljOj have four clear peaks identified as emission due to D-F transitions of Tb3+ state. The luminescence spectra of Tb implanted A12O3 excited by He, Ar and Tb bombardment were almost the same except for the luminescence at the wavelength ranging from 300 to 450 nm, which is caused by strong emission from A12O3 itself. The peak of the luminescence appears at 550 nm, and its intensity depends on the Tb dose. The maximum intensity of luminescence during Tb implantation at room temperature is obtained as the maximum atomic ratio of implanted Tb is 2–3 atomic %.
Spreading Resistance Profiling Study of GeSi/Si Structures by High Dose Ge Implantation into Si
Authors: Cheung W.Y. , Wong S.P. , Wilson I.H. , Zhang Tonghe , Chu Paul K.
Published: April 2011

Hetero-structures of GeSi layers on Si have been produced by high dose Ge implantation into p-type (100) Si wafers at 150 or 300 keV at various doses. From spreading resistance profiling measurements, it is found that for samples implanted at 300 keV at a sufficiently high dose, there is an unexpected resistivity type conversion due to the Ge implantation. The depths of the n-p junction formed as-implanted can be larger than 1.5 /xm, far beyond the Ge projected range. Upon annealing, the junction position moves toward the surface and eventually stops at a depth corresponding to the thickness of the GeSi layer. However, no such n-p junction formation was observed in the spreading resistance profiles of the 150 keV implanted samples. These spreading resistance results are discussed in conjunction with results from RBS and SIMS experiments.
Oxidation of Silicon Implanted with High-Dose Aluminum
Authors: Yang Zunde , Du Honghua , Withrow Stephen P.
Published: April 2011

Si (100) wafers were implanted with Al at 500°C to high doses at multi-energies and were oxidized in 1 atm flowing oxygen at 1000°–1200°C. The morphology, structure, and oxidation behavior of the implanted and oxidized Si were studied using optical microscopy, atomic force microscopy, and cross-sectional transmission electron microscopy in conjunction with selected area electron diffraction and energy dispersive x-ray analysis. Large Al precipitates were formed and embedded near the surface region of the implanted Si. The oxidation rate of the Al-implanted Si wafers was lower than that of virgin Si. The unique morphology of the implanted Si results from rapid Al diffusion and segregation promoted by hot implantation. The reduction of the oxidation rate of Si by Al implantation is attributed to the preferential oxidation of Al and formation of a continuous difiusion barrier of Al2O3.
Raman Spectroscopic Study of Ag-, W- and Pd-Ions Implanted Polyimde Films
Authors: Watanabe Hiroshi , Takahashl Katsuo , Iwaki Masaya
Published: April 2011

A study has been made of the carbon formation in the surface layer of Ag-, W- and Pd-ions implanted polyimide films. The doses of 130 KeV Ag-ions and 190 KeV W-ions ranged from lxlO16 to 5×1017 atoms/cm2. The doses of 100 KeV Pd-ions ranged from 5×1016 to 2×1017 atoms/cm2. The carbon structure in implanted layers was characterized by laser Raman spectroscopy (LRS). Non-implanted polyimide film has very strong intensity of fluorescence, and the intensity of all W-, Ag- and Pd-ions implanted specimens decreases with the increase in dose. The intensity of Raman spectra for both W- and Ag-ions implanted specimens increases with the increase in dose. For Pd-ion implanted specimens, the Raman spectrum of carbon is hardly observed even with a high dose. Raman spectra for W- or Ag-ions implanted specimens with a high dose show that the diamond-like carbon (DLC) exist in the implanted layers. It is found that the DLC structures in the W- and Ag-ions implanted layers have graphite-like and amorphous-like structures, respectively. We propose that transparency carbon structure in implanted layers is generated by Pd-ion implantation. It is concluded that marked DLC formation in surface layer of polyimide films can be caused by Ag- or W-ions implantation except Pd-ion implantation, and carbon structure in implanted layers depends strongly on the implanted elements.
Neutron Depth Profiling by Large Angle Coincidence Spectroscopy
Authors: Vacík J. , Cervenä J. , Hnatowicz V. , Havränek V. , Fink D.
Published: April 2011

Extremely low concentrations of several technologically important elements (mainly lithium and boron) have been studied by a modified neutron depth profiling technique. Large angle coincidence spectroscopy using neutrons to probe solids with a thickness not exceeding several micrometers has proved to be a powerful analytical method with an excelent detection sensitivity. Depth profiles in the ppb atomic range are accessible for any solid material. A depth resolution of about 20 nanometers can be achieved.
The Characterisation of The Compositional and Electronic Profiles of Delta-Doped Layers Using Transmission Electron Microscopy
Authors: Dunin-Borkowski R.E. , Stobbs W.M.
Published: April 2011

The compositional profile of an interlayer inferred from Fresnel contrast data is usually determined assuming that the variation in the measured mean forward scattering potential is associated with changes in neutral atom scattering factor and atomic density. However, the technique is currently being applied to systems for which the form and the magnitude of the potential at the layer can be affected strongly by changes in ionicity. Here, we show how the analysis of ‘delta-doped’ layers in semiconductors, which contain thin layers of impurity ions at low concentrations, requires the analysis of not only the effect of strains on the density but also the contribution to the potential from charged ions surrounded by a wider spread of free carriers.
Chemistry and Deposition Driven by Monoenergetic Synchrotron Radiation: Initial Studies of Condensed Silanes and Water on Noble Metals
Authors: Moore J.F. , Chaturvedi Sanjay , Strongest DR.
Published: April 2011

We extend previous work in broadband synchrotron radiation (SR) excitation of condensed multilayers to the study of reactions driven by monoenergetic SR. The long term goal of this work is to understand the importance of core-level excitation on the reactions that lead to materials growth. Results are presented for two systems of interest: formation of silica from Si(CH3)4 and H20 mixtures with 90 eV irradiation (below the core levels) and the energy dependence of the reaction of SiH4 and H2O.
Equal Thickness Contours of Films Deposited on Inclined Substrates by Evaporation and Ion Beam Assisted Deposition
Authors: Franzen W. , Demaree J.D. , Fountzoulas C.G. , Hirvonen J.K.
Published: April 2011

A study is presented of the geometrical shape of deposition contours that arise when material is evaporated from a point source onto an inclined substrate, an arrangement common in ion-assisted deposition. The shape of the contours, as determined by the inverse square law and the angles of emission and incidence, is described by a fourth-order algebraic equation in polar coordinates on the surface of the substrate. The equation defines a family of distorted ellipses whose form depends on the angle of tilt. An experimental test of these relations by electron-beam deposition of an ion-bombarded oil film on a tilted silicon wafer will be reported.
Morphology and Microstructure of (111) Crystalline CeO2 Films Grown on Amorphous SiO2 Substrates by Pulsed-Laser Ablation
Authors: Zhu S. , Lowndes Douglas H. , Budai J.D. , Thundat T. , Norton D.P. , Warmack R.J.
Published: April 2011

The surface morphology and microstructure of (lll)-oriented CeO2 thin films, grown on amorphous fused silica (S1O2) substrates by low-energy-ion-beam assisted pulsed laser ablation, have been studied by atomic force microscopy (AFM) and x-ray diffraction (XRD). These CeO2 films are aligned with respect to a single in-plane axis despite being deposited on an amorphous substrate. There is a honeycomb-like growth morphology to the films and island-growth can be observed in thicker films. These islands, inside of which are high density of honeycomb-like clusters, are separated by a void network with ∼700nm width. However, on the surface of the thinnest film (∼3nm), only very small clusters (diameter <60nm) appear, and the boundaries of the void network are undefined, which implies that the film is just beginning to coalesce into clusters (grains). The combined AFM images and XRD pattern suggest these clusters probably are the initial seeds for the subsequent island growth. Based on these results, the growth mechanism of oriented CeO2 films on amorphous fused silica substrates is discussed.
Study of Wsi2 and Cosi2 Thin Films Deposited by Laser Ablation
Authors: Glebovsky V.G. , Ermolov S.N. , Oganyan R.A. , Stinov E.D.
Published: April 2011

It has been shown, that pure massive targets of tungsten and cobalt disilicide can be obtain from the liquid state by means of a set of metallurgical methods. The conditions of laser ablation of the targets ensuring the preparation of tungsten and cobalt suicide films of the specific electric resistance 50 and 30 μΩ cm respectivly have been studied. The grazing beam X-ray difractometry were used to investigate their phase and elemental composition of the films. The method in question has been shown to be promising for the preparation of films of other refractory - metal suicides.
Ion-Beam Polishing of Diamond Thin Films
Authors: Lee Dong-Gu , Singh Rajiv K.
Published: April 2011

Planarization of diamond thin films has been carried out using a remote electron cyclotron resonance (ECR) oxygen plasma under a negative bias. Diamond thin films were synthesized by hot filament chemical vapor deposition (HFCVD). The surface roughness (RJ of the diamond films could be considerably reduced from 0.2 μπι to 0.05 μπι using the ECR oxygen plasma. Low planarization and a high etching rate of diamond films were observed for an incident angle of the ion beam to the film surface normal below 45 degrees. High applied bias above -600 V caused secondary discharge effects, resulting in inhomogeneous etching. With an increase in incident angle, needlelike morphology was observed in the diamond film.
1XThin Films Prepared By Mass Separated Ion Beam Deposition
Authors: Hofsäss H. C. , Ronntng C. , Griesmeier U. , Gross M.
Published: April 2011

We have studied the growth and the properties of CN films prepared by deposition of mass separated12C+and14N+ions. The film thickness and density were determined as a function of ion energy between 20 eV and 500 eV and for substrate temperatures of 20 °C and 350 °C. Sputtering effects limit the maximum N concentration to about 30 - 40 at.% even for ion energies as low as 20 eV. IR absorption measurements indicate predominantly C-N and C=N bonding and an amorphous or strongly disordered CN-network. For room temperature deposited CN films with N concentrations up to 25 at.% I-V curves of metal-CN-metal devices show Frenkel-Poole behavior due to field-enhanced thermal activation of localized electrons. Films deposited at 350 °C have N concentrations below 15 at.% and graphitic properties like low resistivity and a density close to graphite.