bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Investigation of a Novel Method to Vitrify Biological Tissues Using Pulsed Lasers and Cryogenic Temperatures
Authors: Kandra Deepak , Charalampopoulos Tryfon , Devireddy Ram
Published: March 2009

The ability to eliminate freezing damage using “vitrification” (or the formation of glass) has long been an area of intense interest in cryobiology. Typically vitrification is achieved when biological systems are cooled at rates ranging from ∼8,000 °C/min to ∼10,000 °C/min [1–5]. Using traditional cooling methods (immersion in liquid nitrogen), such high cooling rates are currently not achievable, in large tissue sections (∼cm’s). In the present study we investigate a novel method to achieve high cooling rates in large tissue sections by pulsed laser heating in conjunction with cryogenic temperatures, i.e. high cooling rates are achieved by the localized difference in temperature between the laser heated tissue (∼1000’s of °C) and the surrounding liquid nitrogen (∼−160 °C). Additionally, the use of pulsed lasers allows localized heating of the tissue coupled with small time scales of energy deposition (0.1 to 1 pico seconds) such that the heating/thermal damage in tissues is minimized. To amplify this idea further, we developed a numerical model to predict the temperature transients in tissues exposed to laser heating and cryogenic temperatures. Analysis of our numerical simulations suggest that a perturbation of ∼3500 °C in a 5mm thick tissue leads to cooling rates in excess of ∼8000 °C/min throughout the tissue slice. These results indicate the possibility of vitrifying large tissue sections of cryobiological relevance using a combination of laser heating and liquid nitrogen cooling.
Two Dimensional Simulation of Heat Transfer and Fluid Flow in a Rectangular Natural Circulation Loop Containing PCM Suspensions
Authors: Ho C. J. , Chiu S. Y. , Lin J. F.
Published: March 2009

A two-dimensional numerical simulation, via a finite difference method, of fluid flow and heat transfer in a rectangular natural circulation loop is presented to explore efficacy of using solid-liquid phase change material (PCM) suspensions as a heat transfer medium. A continuum mixture flow model is used for the buoyancy-driven circulation flow of the PCM suspensions together with an approximate enthalpy model to describe the solid-liquid phase change (melting/freezing) process of the PCM particles in the loop. Parametric simulations have been conducted for the pertinent physical parameters of a loop with fixed geometrical configuration in the following ranges: the modified Rayleigh number Ra* = 109 ∼ 1013, the modified Stefan number Ste* = 0.05 ∼ 0.5, the particle volumetric fraction cv = 0 ∼ 20%, and the modified subcooling factor Sb* = 0∼2.0. The melting/freezing processes of the PCM particles at the heated/cooled sections of the loop are closely interrelated in their inlet conditions of the suspension. Closer examination of numerical results reveals that there could be a flow regime in the parametric domain where heat transfer performance of the suspension circulation loop is significantly enhanced, due to contribution of the latent heat transport associated with melting/freezing of PCM particles.
Is “Complete” Spreading Really Complete?
Authors: Alteraifi Abdullatif M. , Moet Abdelsamie
Published: March 2009

The kinetics and mechanisms of complete spreading of polydimethylsiloxane (PDMS) droplets on a solid substrate were examined to discern the limits of the hydrodynamic regime and to identify the nature of the subsequent transport processes. Experiments were conducted on PDMS-1000 in comparison with glycerin on soda-lime glass. The kinetic data were analyzed within the context of a thermodynamic framework which accounts for the driving force of droplet spreading as the difference between Laplace pressure and the solid/liquid interfacial energy. As Laplace pressure within the droplet was depleted to a minimum the glycerin droplet ceased to spread and the PDMS droplet was caused to transform into a 100 micrometer thin film spreading in a Fickian-type behavior. Contrary to the monolayer notion, the diffusive transport of the liquid film ended up with fragmented island domains hopping over the solid substrate, probably driven by short range forces. Based on the evidence gathered in this study what is generally accepted as “complete” spreading falls into three distinct regimes: Hydrodynamic regime, diffusive regime and fragmented islands regime; each is driven by a different mechanism. In analogy with other liquids, PDMS is suggested to exhibit partial wetting with small, but finite, equilibrial contact angle of about 8 degrees. Diffusive and fragmented island regimes are likely a manifestation of the unusual molecular mobility of the PDMS molecules.
Structure Detection and Analysis of Non-Circular Impinging Jets in a Semi-Confined Array Configuration
Authors: Dano Bertrand P. E. , Liburdy James A.
Published: March 2009

The modal kinetic energy distribution and instantaneous vortex field of an impinging confined jet array is investigated. The jet array consists of 7-by-7 equally spaced orifice nozzles, using two nozzle cross sections: circular and cusped ellipse. Digital Particle Image Velocimetry (DPIV) is used to determine the velocity field of the impinging jets along the center row in the plane parallel with the cross flow direction. Proper Orthogonal Decomposition (POD) and vortex detection algorithms are used to analyze the results of 50 instantaneous velocity fields in the impingement regions for each of several jets located along the crossflow direction. The energetic content of the flow is evaluated based on the POD eigenvalue distribution, the number of POD modes necessary to reconstruct the instantaneous velocity field, and the modal turbulent kinetic energy distributions. Vortex detection algorithms are used to locate and quantify the nature of the instantaneous vortices within the flow. Results of the vortex identification and the associated kinetic energy distribution within the flows are used to indicate the overall sensitivity to the nozzle geometry. The results suggest that the cusped ellipse nozzle when oriented with its major axis parallel to the flow, because of axis switching, can provide increased surface interactions which may lead to enhanced rates of heat and mass transfer.
Remelting and Coalescence of Molten Metal Droplets Deposited on a Plate
Authors: Fang M. , Chandra S. , Park C. B.
Published: March 2009

An experimental study was conducted to study coalescence of molten tin droplet deposited on an aluminum plate that was moving horizontally. A pneumatic droplet generator was used to produce molten tin droplets on demand. Coalescence of droplets placed on a horizontally moving surface depended on both substrate temperature and the degree of overlap between droplets. Continuous beads could be produced if the substrate temperature was kept above 175°C and droplets overlapped by a distance equal to half their diameter. If either substrate temperature or droplet overlap distance was too small surface tension driven instabilities forced the bead to break up. A simple mass conservation model was used to predict the width of beads formed by droplet coalescence.
A Two-Temperature Model for Solid/Liquid Phase Change in Metal Foams
Authors: Krishnan Shankar , Murthy Jayathi Y. , Garimella Suresh V.
Published: March 2009

Transient solid/liquid phase change occurring in metal foams impregnated with phase change material (PCM) is investigated. Natural convection in the melt is considered. Volume-averaged mass and momentum equations are employed, with the Brinkman-Forchheimer extension to the Darcy law to model the porous resistance. Owing to the difference in the thermal diffusivities between the metal foam and the PCM, local thermal equilibrium between the two is not assured. Assuming equilibrium melting at the pore scale, separate volume-averaged energy equations are written for the solid metal foam and the PCM, and are closed using an interstitial heat transfer coefficient. The enthalpy method is employed to account for phase change. The governing equations are solved implicitly using a finite volume method on a fixed grid. The influence of Rayleigh number, Stefan number, and interstitial Nusselt number on the temporal evolution of the melt front location, temperature differentials between the solid and fluid, and the melting rate is documented and discussed. The merits of incorporating metal foam for improving effective thermal conductivity of thermal storage systems are discussed.
Modeling and Sensing for Penetration Control of the SAW Process in the Presence of Welding Perturbations
Authors: Ravala Nanda K. , Fan Haibo , Wikle H. C. , Chin Bryan A.
Published: March 2009

A study was conducted to investigate the feasibility of using a point infrared sensor to monitor and control the penetration during the Submerged Arc welding (SAW) process. The SAW process, using small tractor welding units, is extensively used in the ship building industry because of the high deposition rates that may be achieved. Typical problems encountered by these welding units include seam gap variations, plate offset, changes in thickness, tracking misalignment, plate inclinations and heat sinks such as stiffeners, chill blocks and temporary buckling restraints. Each of these perturbations causes a change in the temperature distribution that may be identified using infrared sensors. A simple numerical heat transfer model using the Finite Element Analysis (FEA) package ALGOR was constructed to predict the heat flow patterns and thermal distributions that occur in the presence of step changes in thickness and heat sink perturbations. Bead-on-plate welding trials were then done on A-36 carbon steel and monitored using an infrared sensor to compare predictions with experiment. Good agreement was observed when predictions were compared with experiments. The measured changes in infrared signal corresponded well with the predicted results both in terms of time of occurrence and relative magnitude of signal. The results of the experiments suggest that infrared sensors may be used to identify and control process perturbations that occur during the SAW process. Future experiments will utilize the signals from IR sensors to control welding current and provide automatic control to obtain constant penetration during the SAW process.
Shape Optimization of Multi-Element Airfoils Using Evolutionary Algorithms and Hybrid Unstructured Framework
Authors: Ahuja V. , Hosangadi A. , Lee Y. T.
Published: March 2009

In this paper we present design optimization studies of multi-element airfoils utilizing evolutionary algorithms. The shape optimization process is carried out by utilization of high fidelity CFD based comprehensive framework. The framework comprises of a genetic algorithm based design optimization procedure coupled to the hybrid unstructured CRUNCH CFD® code and a grid generator. The genetic algorithm based optimization procedure is very robust, and searches the complex design landscape in an efficient and parallel manner. Furthermore, it can easily handle complexities in constraints and objectives and is disinclined to get trapped in local extrema regions. The fitness evaluations are carried out through a RANS based hybrid unstructured solver. The utilization of hybrid unstructured methodology provides flexibility in incorporating large changes in design and mesh regeneration is carried out in an automated manner through a scripting process within the grid generator GRIDGEN. The design optimization procedure is carried out simultaneously on both the stabilizer and the flap. Shape changes to the trailing edge of the flap strongly influence the secondary flow patterns that set up in the gap region between the stabilizer and the flap. These, in turn, are found to have a profound influence on lift and torque characteristics. The paper will discuss these results and provide details of the optimization procedure including coupling with hybrid unstructured framework and grid generator.
Stability of Convection in a Vibrating Porous Layer
Authors: Govender S.
Published: March 2009

The linear stability theory is used to investigate analytically the effects of vibration on convection in a homogenous porous layer heated from below. The gravitational field consists of a constant part and a sinusoidally varying part, which is tantamount to a vertically oscillating porous layer subjected to constant gravity. The linear stability results are presented for the specific case of low amplitude vibration for which it is shown that increasing the frequency of vibration stabilizes the convection.
Combination of Impingement and Trip Strips for Combustor Liner Backside Cooling
Authors: Hebert Ryan , Ekkad Srinath V. , Khanna Vivek
Published: March 2009

Effective cooling of modern low NOx combustor liners is achieved through combinations of impingement and other heat transfer enhancement methods. In the present study, a combination of impingement and trip strips is studied to determine the optimum location of trip strips with respect to impingement jet arrays. Heat transfer with pure impingement has degradation downstream due to increased cross-flow effects. To counter the cross-flow induced heat transfer degradation, a combination technique wherein impingement is combined with ribs placed in between impingement rows or downstream of the impingement array is studied. Three configurations with increased rib placements and reduced impingement holes are studied and compared with pure impingement cases for the same jet Reynolds number. Three jet Reynolds numbers are studied for Rej = 10000, 20000, and 30000. Detailed heat transfer distributions are obtained using the transient liquid crystal technique. Results show that the presence of ribs increases jet impingement heat transfer on the surface with lower mass flows. The effectiveness of the combination ribs and impingement can provide higher heat transfer with reduced cooling air requirements.
A Three-Dimensional Transient Numerical Study of a Close-Coupled Catalytic Converter Internal Flow
Authors: Ramadan Bassem H.
Published: March 2009

Recently, the new regulations on emission standards have prompted a reconsideration of the design of automotive catalytic converters in order to reduce the light-off period of the catalyst. The catalytic converter light-off period is very Important since almost 80% of the emissions from vehicles occur within the first three minutes after cold start in the FTP-75 test. In order to meet these new regulations, current studies have suggested that the catalyst should be “close-coupled”; that is fitted close to the engine exhaust manifold. In order to design “close-coupled” converters, the designer may have to resort to truncated inlet and outlet cones, or distorted inlet pipes due to space limitations. Hence, it is very difficult to achieve good mixing of the exhaust gas, and a good flow distribution at the inlet cross section of the monolith. Based on such a current status in the study of the catalytic converter, the present work focuses on the time-dependent flow patterns, both in the exhaust manifold and the catalytic converter using Computational Fluid Dynamics (CFD). A three-dimensional grid model of an engine exhaust manifold and a close-coupled catalytic converter was developed and analyzed. The flow simulations were performed using KIVA-3 for non-reacting flow fields. These simulations were performed with transient boundary conditions applied at the inlet to the exhaust runners to simulate the opening and closing of exhaust valves. The CFD results were used to study flow uniformity under different operating conditions and to identify the best location of the oxygen sensor.
Rhodamine Based Sensors for Laser Induced Fluorescence for Droplet Temperature Measurements
Authors: Salazar V. , Gonzalez J. E. , Rivera L. , Rivera L. A.
Published: March 2009

Rhodamine based sensors for applications in laser induced fluorescence thermometry were tested, and optimized. Laser Induced Fluorescence (LIF) is an optical non intrusive technique for temperature measurements. The technique uses a temperature sensitive dye, which is excited by a laser sheet providing spatial temperature diagnostic. The fluorescent dyes Rhodamine B and the Rhodamine 110, were used in combination with water. Thus in the present work the main findings regarding to the sensors: RhodamineB-water, RhodamineB-ink, RhodamineB/110-water, and RhodamineB/110-ink, are reported.
Comparison of the Structures of a Perturbed and Unperturbed Boundary Layer of the Same Reynolds Number
Authors: Oyewola O.
Published: March 2009

The comparison of the structures of the boundary layer with and without suction of the same momentum thickness Reynolds number Rθ have been made in a turbulent boundary subjected to concentrated suction, applied through a short porous wall strip. The results indicate that, relative to σ = 0, the mean velocity collapses reasonably well but there are some discrepancies in the Reynolds stresses distributions. These discrepancies are also noted in the distributions of the anisotropy invariant tensor, skewness and flatness factors. The result would suggest that the differences are a result of the difference in the initial boundary condition, which influences the flow structures to a significant streamwise location.
Rheological Aspects of Drops Deforming in Finite Reynolds Number Oscillatory Extensional Flows
Authors: Li Xiaoyi , Sarkar Kausik
Published: March 2009

The evolving morphology of droplets in a flowing emulsion determines its rheological properties. A two-way interaction between drops and the flow governs the rheological stresses arising from drop deformation. In this paper, the rheology of droplet emulsions under oscillatory extensional flow is investigated using direct numerical simulation (DNS). The deformation of a three dimensional drop is simulated. The rheological responses are related with the interface morphology using Bachelor’s stress formulation [6]. Detailed investigation of the variation of parameters such as interfacial tension, flow frequency and inertia displayed complex non-Newtonian response of the emulsion that will have broad implication in industrial applications. The results are explained and discussed with a simple model for the drop dynamics.
Enhancement of Oxygen Transfer in Liquid Lead-Bismuth Eutectic by Natural Convection
Authors: Ma Jian , Guo Peng , Zhang Jinsuo , Li Ning , Fu Bingmei
Published: March 2009

This article presents numerical analysis of natural convection and oxygen transfer of low-Prandtl-number (∼0.02) lead bismuth eutectic (LBE) for testing and calibrating oxygen sensors. This analysis is done on the two-dimensional coordinates in a rectangular container, when the fluid movement is laminar for the purpose of sensor test and calibration. The oxygen supply is from the bottom of the container. Natural convection and mass transfer are examined under several temperature boundary conditions: a) If heated from the lower part and cooled from the upper part of the sidewalls, there are four convective circulation cells. This will not benefit oxygen transfer from the bottom to the top of the container. b) If heated from the sidewalls and cooled from the top and the bottom of the container, there are two convective circulation cells side by side. This will lead to a weak oxygen transfer between left and right parts of the container. c) If one sidewall heated and the opposing wall cooled, there is a single convective circulation cell. This will produce intensive convective motion in the whole flow field. The simulation results show that the most efficient way to enhance oxygen transfer by natural convection is condition c). Under this condition, it takes about 12 minutes for the oxygen concentration in the whole field to reach ∼95% of the input oxygen concentration from the bottom, instead of ∼70,000 hours by pure diffusion.
Experimental Investigation on the Correlations of the Holdup and the Frictional Pressure Drop of Gas-Liquid Two-Phase Flow in a Flat Capillary Rectangular Channel
Authors: Ide Hideo , Fukano Tohru
Published: March 2009

Experiments on the horizontal and the vertical upward gas-liquid two-phase flows were done to clarify the flow phenomena in a flat capillary rectangular channel. The flow patterns, the passing frequency and the velocity of liquid lumps, the holdup and the frictional pressure drop in two-phase flow were investigated. The dimension of the channel used was 9.9 mm × 1.1 mm. The orientations of the channel were with the wide side vertical and the wide side horizontal. The differences between the flow phenomena in such orientations were investigated. The effects of the orientation of the duct, the aspect ratio of the cross section of the channel, superficial gas velocity and superficial liquid velocity on those two-phase flow parameters were examined. The obtained data of the holdup and the frictional pressure drop could not be correlated well with those correlations which have been proposed so far. New correlations of holdup and frictional pressure drop for a flat capillary channel are proposed. The predictions by those correlations have sufficient accuracy for both the vertical and the horizontal flows.
Transport Phenomena and Their Effect on Weld Quality in GMA Welding of Aluminum Alloys
Authors: Guo H. , Tsai H. L. , Wang P. C.
Published: March 2009

Gas metal arc welding (GMAW) of aluminum alloys has recently become popular in the auto industry to increase fuel efficiency of a vehicle. In many situations, the weld is short (say, less than two inches) and the “end effects” become very critical in determining the strength of the weld. At the beginning stage of the welding, when the metal is still “cold”, which is frequently called cold weld, limited weld penetration occurs. On the other hand, at the ending stage of the welding, a “crater” is formed involving micro-cracks and micro-pores. Both the cold weld and the crater can significantly decrease the strength of the weld and are more severe for aluminum alloys as compared to steels. Hence, there are strong needs to improve the GMAW process in order to reduce or eliminate the aforementioned end effects. In this paper, both mathematical modeling and experiments have been conducted to study the beginning stage, ending stage, as well as the quasi-steady-state stage of GMA welding of aluminum alloys. In the modeling, a three-dimensional model using the volume-of-fluid (VOF) method is employed to handle the free surfaces associated with the impingement of droplets into the weld pool and the weld pool dynamics. Transient weld pool shapes and the distributions of temperature and velocity in the weld pool are calculated. The predicted solidified weld bead shapes, including weld penetration and/or reinforcement, are in agreement with experimental results for welds in the aforementioned three stages. It was found that the thickness of the molten weld pool is smaller and there is no vortex developed, as compared to steel welding. The lack of penetration in cold weld is due to the lack of pre-heating by the welding arc. Three techniques are proposed and validated numerically to improve weld penetration by increasing the energy input at the beginning stage of the welding. The crater formation is caused by rapid solidification of the weld pool when the welding arc is terminated. By reducing welding current and reversing the welding direction before terminating the arc, the weld pool is maintained “hot” for a longer time allowing melt flow to fill-up the crater. This method is validated experimentally and numerically to be able to eliminate the formation of the crater and the associated micro-cracks.
Optimum Refrigerating Efficiency and Exergy Index of a Two-Stage Refrigeration Cycle
Authors: Tiedeman J. S. , Sherif S. A.
Published: March 2009

This paper presents results of an optimization study for a two-stage vapor compression refrigeration cycle based on the refrigerating efficiency and exergy index. Traditional two-stage refrigeration cycle studies have focused on the first law performance, while those studies dealing with the second law have primarily been limited to performance analysis as opposed to performance optimization. Results of this study indicate that the use of the common approximation of the geometric mean to find the optimum interstage pressure leads to nearly optimum results for the refrigerating efficiency, with maximum error in the neighborhood of 5%. However, the error associated with using this approximation to find the optimum exergy index is too large, approaching 15%. Second law optimization revealed that the optimum data curves themselves have maxima for each set of conditions tested. There are a series of conditions that lead to the conclusion that, for a given system, there is an optimum set of conditions that lead to the lowest amount of exergy destruction for that system. Polynomial equations have been fitted to the resultant optimum data for the refrigerating efficiency and exergy index. These equations allow for the reproduction of optimum points based on high- and low-pressure compressor efficiencies and condenser and evaporator pressures.
Nucleation and Growth of Bubble With the Effects of Solute Gas
Authors: Tsuda Shin-Ichi , Takagi Shu , Matsumoto Yoichiro
Published: March 2009

Bubble nucleation and growth of formed nuclei are investigated by molecular dynamics simulation in Lennard-Jones liquid with gas impurities. For the onset of nucleation from bulk, it has been found that a dissolved gas whose interaction is very weak and whose diameter is larger than that of solvent molecules makes the action to cause composition fluctuation or local phase separation so strong that the nucleation probability predicted from pressure change becomes qualitatively wrong. It has been confirmed that this wrong prediction is generally explained by introducing the superheat ratio nondimensionalized by saturation pressure and spinodal pressure. For the growth stage of formed bubble nuclei, it is observed that the coalescence of nuclei occurs when a weak-interaction gas is dissolved at a high concentration while the competition between neighbor nuclei is dominant in the case of pure liquid.
Time-Averaged Velocity, Temperature and Density Surveys of Supersonic Free Jets
Authors: Panda J. , Seasholtz R. G. , Elam K. A. , Mielke A. F.
Published: March 2009

A spectrally resolved molecular Rayleigh scattering technique was used to simultaneously measure axial component of velocity U, static temperature T, and density ρ in unheated free jets at Mach numbers Mj = 0.6, 0.95, 1.4 and 1.8. The latter two conditions were achieved using contoured convergent-divergent nozzles. A narrow line-width continuous wave laser was passed through the jet plumes and molecular scattered light from a small region on the beam was collected and analyzed using a Fabry-Perot interferometer. The optical spectrum analysis provided measures of velocity and static temperature. The local air density at the probe volume was determined by monitoring the intensity variation of the scattered light using photomultiplier tubes. The Fabry-Perot interferometer was operated in the imaging mode, whereby the fringe formed at the image plane was captured by a cooled CCD camera. Special attention was given to remove dust particles from the plume and to provide adequate vibration isolation to the optical components. The velocity profiles from various operating conditions were compared with that measured by a Pitot tube. An excellent comparison within 5m/s demonstrated the maturity of the technique. Temperature was measured least accurately, within 10K, while density was measured within 1% uncertainty. The survey data consisted of centerline variations and radial profiles of time-averaged U, T and ρ. The static temperature and density values were used to determine static pressure variations inside the jet. The data provided a comparative study of jet growth rates with increasing Mach number. The current work is part of a data-base development project for Computational Fluid Dynamics and Aeroacoustics codes that endeavor to predict noise characteristics of high speed jets. A limited amount of far field noise spectra from the same jets are also presented. Finally, a direct experimental validation was obtained for the Crocco-Busemann equation which is commonly used to predict temperature and density profiles from known velocity profiles. Data presented in this paper are available in ASCII format upon request.
Numerical Simulation of a Pool Fire and Large Object in a Cross-Wind
Authors: Devaud Cecile B. , Weckman Elizabeth J.
Published: March 2009

The present investigation is focused on assessing the capabilities of Large Eddy Simulations (LES) using simplified sub-models for combustion and soot in a specific fire scenario. Fire development resulting from an aviation fuel spill close to a plane fuselage is considered. The computational domain and boundary conditions are defined according to the experimental configuration used in tests run by the Fire Research Group at the University of Waterloo. The present setup consists of a 2-m-diameter pool fueled with kerosene and located 1-m-upstream of a 2.7-m-diameter culvert in a large enclosure. A cross-wind with a velocity of 13 m/s is imposed on the fire and culvert. The calculations are time-dependent and three-dimensional. Sensitivity to the grid refinement, size of the enclosure and wind profiles is first investigated. Comparison between measured temperatures and numerical results across the computational domain is made. Velocity profiles are also examined. Reasonable agreement with the experiments is found. In the light of the present results, directions for future work are also discussed.
Development of Fluorination Decontamination Technique for Uranium Bearing Wastes
Authors: Fujiwara Kenichi , Sasaki Tomozou , Saita Yuzou , Kamei A. , Fukui T.
Published: March 2009

A matrix of uranium bearing wastes (sludge, incineration ashes) bonds uranium tightly, and some wastes (narrow pipes, filters, etc.) have complicated shapes. This research was intended to achieve the assumed clearance level (0.3Bq/g) and to reduce the amount of secondary wastes. One of the uranium decontamination processes is the fluorination decontamination process in which CIF3 is used as a decontamination agent to fluorinate uranium bearing wastes to gaseous UF6 which can be recovered by cold or chemical trapping. The research test variables were decontamination temperature, decontamination temperature history and decontamination period. Filters and the main sludge could be decontaminated below the assumed clearance level when treated at 500 °C for 3 hours.
Iron Phosphate Glass as Optional Final Waste Matrix for High-Level Radioactive Waste
Authors: Sazarashi M. , Maruyama K. , Ono S. , Suzuki K. , Fukui T. , Ishinomori T. , Kubota N. , Endo Y.
Published: March 2009

The study investigated experimentally a basic capability of iron phosphate glass (IPG) matrix to vitrify the high level radioactive waste (HLW) in the commercial reprocessing. IPG matrix is a mixture of iron oxide and phosphorus oxide, and Fe/P mole ratio is one of important conditions to form a vitrified product with good chemical and physical properties. Moreover, the corrosion of IPG matrix is more rigorous than that of borosilicate glass matrix, and an appropriate furnace material should be selected for the durability of equipments. The composition of HLW used in experiments was simulated, based on that of HLW generating from commercial reprocessing for a standard spent fuel of light water reactor. Dependence of Fe/P mole ratio on both crystallinity of product and loading of simulated HLW was investigated. At Fe/P mole ratios of 0.43 and 0.33, crystals of Nd and Zr phosphate, appeared in a part of Fe-P matrix zone of vitrified products containing 30wt% of the HLW. The products at Fe/P ratios of 0.18 and 0.27 become a homogeneous glassy state with increasing solubility of crystals of Nd and Zr phosphate. It means that the low Fe/P mole ratio is better to form the vitrified product of high waste loading. Concerned with water resisting property, products vitrified at Fe/P = 0.18,0.23 have larger amount of dissolution rates than that at Fe/P = 0.33,0.43. An appropriate amount of Fe needs to form vitrified product of IPG with good water resisting property, although the homogeneity in micro-structure of the product slightly decreases. Fe/P mole ratio in IPG, 0.3 is an appropriate condition to form vitrified product containing HLW with less dissolution and leaching rate. It is totally concluded that Fe/P mole ratio in IPG, 0.3 is an appropriate condition to form vitrified product containing HLW with less dissolution and leaching rate. This study focused on a special material, ZrB2, which has electric and heat conduction equivalent to iron metal in order to estimate an adoption of furnace material. The corrosion rate of ZrB2 in the melting of IPG matrix was as low as that of Alumina, and there was no rigorous corrosion on the surface of crucible. It was shown that ZrB2 is able to apply a furnace material for IPG vitrification with an induction-heated ceramic melter.
Long-Term In-Package Spent Fuel Criticality Calculations
Authors: Wantz Olivier , Smidts Olivier , Dubus Alain , Beauwens R.
Published: March 2009

This paper presents MCNP criticality calculations for both UOX and MOX disrupted fuel assemblies canisters systems in the reference Belgian disposal concept and one of its variant. We examine the influence of different parameters (water moderation and geometry alteration) on the neutron multiplication factor, keff. In all the studied cases, the reference concept does not present criticality risks. The variant concept sometimes presents criticality risks. The present results only concern fresh UOX and MOX fuel assemblies. Further developments of this work will include irradiated (UOX and MOX) fuels.
Results of a Recent Safety Assessment of a Proposed Deep Geological Repository in the Opalinus Clay of the Zu¨rcher Weinland in Northern Switzerland
Authors: Schneider J. W. , Johnson L. H. , Zuidema P. , Gribi P. , Mayer G. , Smith P. A.
Published: March 2009

A safety assessment of a proposed deep geological repository for the direct disposal of spent UO2 or mixed-oxide fuel, vitrified high-level waste from the reprocessing of spent fuel and long-lived intermediate-level waste in the Opalinus Clay of the Zu¨rcher Weinland of northern Switzerland is described. The assessment methodology is systematic and transparent, and includes the analysis of a broad range of assessment cases, as well as complementary analyses and the formulation of more qualitative arguments. Analyses show compliance with Swiss regulatory Protection Objectives in all cases, and safety indicators complementary to dose and risk further illustrate the low concentrations and fluxes of radioactivity that are expected. No outstanding issues are identified with the potential to compromise safety. The existence of phenomena that are beneficial to safety, but are deliberately (and conservatively) excluded from the assessment (reserve FEPs) indicates that the actual performance of the repository will be even more favourable than the results of the analyses suggest.
Oak Ridge Reservation Department of Energy Facilities: Waste Management Challenges and Success Stories Focusing on Waste Minimization
Authors: Brill Angie , Scott Jeff , Patterson John
Published: March 2009

Waste generation and disposition is a challenge all face in the environmental restoration business. Over the past three years Safety and Ecology Corporation (SEC) working with Bechtel Jacobs Company, LLC (BJC) the Management and Integration subcontractor for the U.S. Department of Energy (DOE) have been able to minimize the volume of waste (mixed, hazardous, and radiological) that is disposed of and increased the volume for release, reuse, and recycle. This paper will focus on the success and challenges of several projects at the Oak Ridge National Laboratory (ORNL) and one project at the East Tennessee Technology Park (ETTP). SEC is one of four Remedial Action/Decontamination & Decommissioning (RADD) subcontractors selected by BJC to support site clean up goals. Several of these RADD projects awarded to SEC will be used to illustrate the waste management process and the challenges/successes to completion. All these projects were “fixed price” with defined milestones keyed into award fee for BJC and regulatory milestones for DOE. From the first project completed under the RADD subcontract to the most recent the waste disposition approach has been refined and a decision process developed. This decision process will be discussed in the paper and illustrated graphically to indicate the critical elements to selecting the most appropriate waste disposition option. This paper will focus on the following items associated with waste minimization efforts at the Oak Ridge Reservation DOE facilities. • Waste disposition decision process. • Waste disposition options — recycle, reuse, salvage, and disposal. • Elements of integration required for successful pre-planning — design and implementation. • Waste disposition challenges and solutions. • Decontamination to reduce mixed waste volumes. Release surveys required to disposition waste for reuse/recycle. • Lessons learned that will be integrated in future projects.
Enhancing the Sorption of Uranyl Ions in the Presence of Carbonate Ions on Zeolite and Mesoporous Materials
Authors: Kazemian H. , Mobtaker H. Ghasemi , Mallah M. H. , Motamedi M. , Mohsen M. Abbas , Nejad A. M.
Published: March 2009

In this study the effect of carbonate concentration on the sorption of uranyl ion from wastewaters was investigated. In the presence of carbonate ions, uranyl cation form a stable anionic complex which disturbs the removal of uranyl by cation exchangers such as zeolite P and A. These zeolites were loaded with some cations and investigated for the sorption of the complex. The sorption of uranyl by a surfactant-modified zeolite was investigated too. Because of low selectivity of these samples, a MCM-41/ZSM-5 composite was synthesized and loaded with a cation and the sorption of mentioned complex by composite was also investigated and the results were promising.
Natural and Engineered Barriers in a Romanian Disposal Site for Low and Intermediate Level Waste
Authors: Diaconu Daniela , Birdsell Kay , Zyvoloski George
Published: March 2009

The operational waste generated by the Cernavoda Nuclear Power Plant will be disposed in a near-surface facility. The low and intermediate level wastes, containing particularly large concentrations of C-14 and H-3, are treated and conditioned in steel drums, which will be placed in the disposal cells and then immobilized in concrete. The Saligny site has been proposed for LIL waste disposal. Geologically, the main components of this site are the quaternary loess, the Precambrian and pre-quaternary clays, and the Eocene and Barremian limestones. Hydrologically, the site can be divided into a vadose zone down to 45–50m and three distinct aquifers, two of them in the limestone beds and the third into the lenses of sand and limestone existing in the pre-quaternary clay layer. Preliminary performance assessments, presented in this paper, indicate that the geologic layers are efficient natural barriers against water flow and radionuclide migration from the vadose zone to the Barremian aquifer. The semi-arid climate and the low precipitation rate prevent contaminant transport from the disposal site to the Eocene aquifer. FEHM simulations of transient groundwater flow showed that seasonal variations influence the moisture content profile in the top of the vadose zone, but the influence over the long term is not significant for contaminant transport. The Danube River level variations control water movement in the Barremian aquifer, especially in the upper part where the limestone is highly fractured and water moves toward the river when its level is low and toward the site when the river level is high. The disposal concept tries to combine the natural and engineered barriers in order to ensure the safety of the environment and population. Therefore, the concrete filling the disposal cells surrounds the waste with a medium that facilitates C-14 retention by precipitation, thus reducing the C-14 releases in the atmosphere and geosphere.
History of Groundwater Chemistry Changes (1979–2001) at the Nabarlek Uranium Mine, Australia
Authors: Waggit Peter W. , Hughes Alan R.
Published: March 2009

The Nabarlek uranium mine is located in the Alligator Rivers Region of the Northern Territory of Australia. The site lies in the wet/dry topics with an annual rainfall of about 1400mm, which falls between October and April. The site operated as a “no release” mine and mill between 1979 and 1988 after which time the facility was mothballed until decommissioning was required by the Supervising Authorities in 1994. The dismantling of the mill and rehabilitation earthworks were completed in time for the onset of the 1995–96 wet season. During the operational phase accumulation of excess water resulted in irrigation of waste water being allowed in areas of natural forest bushland. The practice resulted in adverse impacts being observed, including a high level of tree deaths in the forest and degradation of water quality in both ground and surface waters in the vicinity. A comprehensive environmental monitoring programme was in place throughout the operating and rehabilitation phases of the mine’s life, which continues, albeit at a reduced level. Revegetation of the site, including the former irrigation areas, is being observed to ascertain if the site can be handed back to the Aboriginal Traditional Owners. A comprehensive review of proximal water sampling points was undertaken in 2001 and the data used to provide a snapshot of water quality to assist with modelling the long term prognosis for the water resources in the area. While exhibiting detectable effects of mining activities, water in most of the monitoring bores now meets Australian drinking water guideline levels. The paper reviews the history of the site and examines the accumulated data on water quality for the site to show how the situation is changing with time. The paper also presents an assessment of the long term future of the site in respect of water quality.
Development of PA/SA for LILW Repository in Slovenia Through the IAEA Cooperation
Authors: Zˇeleznik Nadja , Mele Irena , Petkovsˇek Borut
Published: March 2009

ARAO is the Slovenian public agency responsible for the disposal of radioactive waste. Presently its most important mission is the siting of a repository for low and intermediate level waste (LILW) in Slovenia. Although a location for a repository has no yet been selected, important preliminary activities are ongoing. One of the most important is the preparation of performance and safety assessment (PA/SA) for the planned LILW repository. The work is performed by the joint PA/SA team, which is managed and coordinated by ARAO. The work started already in 1997 with the clarification of the objectives of the PA/SA procedure. In 1999 the first preliminary performance assessment of two safety cases — surface and underground LILW repository on a generic site — was realized. In 2001 ARAO successfully applied for the IAEA technical co-operation (TC) program, which gave fresh impetus to the Slovenian PA/SA activities. Simultaneously with the on-going IAEA programme on PA/SA, our national case is also being developed. In 2002 the deterministic performance assessment for a LILW repository on a generic site was completed. The review of the PA/SA report performed by the IAEA expert mission in May 2003 was very positive about the results and the achieved level of expertise of the joint PA/SA team. It is hoped that the team will be ready to carry out a full performance and safety assessment of the site as soon as it is confirmed. In this paper the work and the results of the joint PA/SA team performed so far, and future plans with the emphasis on the IAEA technical co-operation are presented.
A Computational Model for Estimating the Cost of Spent Fuel and High-Level Radioactive Waste Transport
Authors: Johnson E. R. , Best R. E.
Published: March 2009

JAI has developed a simple computer program for use in determining a preliminary estimate of costs for transporting spent nuclear fuel or high-level radioactive waste by legal weight truck or by rail. The JAI Corporation Spent Fuel and High-Level Radioactive Waste Transportation Cost Model © is a Microsoft Excel 2000-based collection of spreadsheets. Both the truck and rail sub-models consist of three spreadsheets, or modules — as follows: • The “Input” spreadsheet accepts the user’s inputs (the user’s configuration of the transportation scenario to be modeled); • The “Cost Calculations” spreadsheet lists cost components and associated calculations; • The “Results” spreadsheet summarized the calculated transportation costs. The program does not calculate costs between two specific points, but rather over a specific distance. The individual inputs required can be entered by the user — or the user can accept the default values built into the program. The input to the program is divided into the following elements: 1. Scenario configuration; 2. Financial assumptions; 3. Capital-related costs; 4. Operating costs; 5. Freight-related costs; 6. Security-related costs. The rail portion of the program also permits the calculation of the cost of heavy haul and barge transport. The cost calculation spreadsheet contains all the algorithms used for calculating each element of cost and summing them — and the results spreadsheet shows the separate cost of capital, operations, freight, security and miscellaneous costs, plus the total cost for the shipment(s). The program offers an easy way for obtaining preliminary estimates of the cost of transporting spent fuel or high-level radioactive waste, and a way to quickly estimate the sensitivity of transport costs to changes in conditions or shipping scenarios.
Transparency in Practice: UK Nirex Limited and Access to Information
Authors: Watson Jenny , Dalton John
Published: March 2009

In 1997 Nirex failed to obtain planning permission to build an underground laboratory (Rock Characterisation Facility) near the Sellafield nuclear site in Cumbria, North-West England. This stopped the UK’s deep disposal programme. Since then there has been much discussion on how the UK should take the issue of long-term radioactive waste management forward. As part of its contribution to the ongoing debate, Nirex needed to reassess how its role in finding a long-term solution could be better played given its history. It has been suggested that the processes required to deal with such a contentious issue, the conduct of individuals and the structural relationships between organisations, all need to change if any progress is to be made. Specifically, one of the difficulties of the past was the lack of a mechanism to allow all stakeholders and the public to clearly see what had been decided and for what reasons. It is suggested that central to these changes needs to be a strong ethical framework based on transparency. This paper will provide an overview of the Nirex Transparency Policy, its operation and some observations of putting it into practice. As a method of ensuring that Nirex does not get complacent about this important aspect of their work, it established an Independent Transparency Review Panel. As part of this panel’s remit they conduct an annual review of the operation of Nirex’s Transparency Policy. Some conclusions and recommendations of operating such a policy will be discussed as will the implications of forthcoming legislation.