bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational and Experimental Investigation of Unsteady and Acoustic Characteristics of Counter-Rotating Fans
Authors: Brailko I. A. , Mileshin V. I. , Nyukhtikov M. A. , Pankov S. V.
Published: March 2009

The matter of developing counter-rotating fans for advanced next generation aeroengines with ducted and unducted propfans is very important [1]. Counter-rotating fans can be made with fixed blades. This article considers tractor propfans consisting of two counter-rotating rotors of variable pitch (VPR) which valuable property is the possibility to turn their blades about the radial axis in order they can take the optimal position in direct thrust regimes, and to obtain a reverse thrust when turning them by a rather large angle. In this case there is no necessity to use a bulky special clamshell-type thrust reverser. In the 1-st phase of designing new CRFs it is necessary, by calculation or experimentally, to show the possibility of obtaining gasdynamic effectiveness of such fans up to the level of single-rotor fans or, at least, to obtain η*ad.f ≥ 0.90÷0.91. But the main thing is to substantiate the feasibility of getting high acoustic characteristics. CIAM (Central Institute of Aviation Motors) is carrying out calculation-experimental investigations of the SV-92 ducted counter-rotating propfan (DCRP) model (the SV-92 is an advanced fan for ultra-high bypass ratio engine [2]) as well as the SV-27 CRF (Fig. 1, Table 1) with unducted rotors for the test aircraft. This paper presents some results on gasdynamic and acoustic characteristics for the SV-27 CRF only. These investigations are aimed at providing the meeting of the test aircraft perceivable noise to ICAO chapter IV regulations.
New 3D Inverse Navier-Stokes Based Method Used to Design Turbomachinery Blade Rows
Authors: Mileshin Viktor I. , Orekhov Igor K. , Shchipin Sergey K. , Startsev Andrew N.
Published: March 2009

Present paper contains a method of solution of inverse problem for Navier-Stokes equations for 3D flows without any simplification of the problem statement and applied to design of turbomachinery bladed rows. In the developed method blade surface is impermeable and no-slip or any other boundary condition compatible with Navier-Stokes equations is applied on the blade surface. Solution of inverse problem is determined using moving grid, which is re-generated at each step of time-marching procedure (variation of flow-rate, impulse and energy fluxes due to movement of grid nodes is taken into account). Normal speed of face of grid cell adjacent to blade surface is determined using given static pressure (inverse mode) with the aid of relationships which are the elements of Godunov scheme applied for integration of flow equations.
Empirical Heat Transfer Models of Single- and Multiple-Nozzle Spray Cooling for Electronics
Authors: Shedd Timothy A. , Pautsch Adam G.
Published: March 2009

The performance of single- and four-nozzle spays for high heat flux electronics cooling using nitrogen-saturated FC-72 was evaluated in this study. The testing was performed using a multichip module (MCM) test setup, similar to MCM’s used in current high-end computer systems. The MCM contained eight test chips; four of these were cooled by single-nozzle sprays and four by four-nozzle sprays simultaneously. The swirl-atomizing, full-cone spray nozzles were incorporated into a production spray plate and were positioned about 6 mm above the test chips. An additional facility was constructed for visualization of the sprays and heat transfer behavior using clear heating elements coated with an indium titanium oxide (ITO) film. Using both the heat transfer and visualization data, it was determined that the heat transfer could be broken down into two or three components: a dominant single-phase component in and around the spray impact, a two-phase liquid film boiling component in the corners away from the spray impact, and, for the multiple-nozzle sprays, a single-phase drainage flow component. Multi-part empirical models were generated based on this conceptual model, and the correlations predict the data to within 5%. In addition, a phenomenological critical heat flux (CHF) model was generated based on previous work with thin liquid-film boiling that suggests CHF in thin films occurs due to a homogeneous nucleation mechanism. This model predicts the current data to within 12% for both single- and four-nozzle arrays.
Cross-Sectional Imaging of the Liquid Film in Horizontal Two-Phase Annular Flow
Authors: Rodri´guez Daniel J. , Shedd Timothy A.
Published: March 2009

Planar laser induced fluorescence (PLIF) was applied to horizontal air/water two-phase annular flow in order to clearly image the liquid film and interfacial wave behavior at the top, side and bottom of the tube. The visualization section was fabricated from FEP, which has nearly the same refractive index as water at room temperature. This index-matched test section was used to allow imaging of the water to within approximately 10 microns of the 15.1 mm I.D. tube wall. A small amount of dye was added to the water with a peak excitation wavelength near that of a pulsed Nd:YAG laser (532 nm). The laser system generated an approximately 5 ns pulsed light sheet at 30 Hz. Images of the liquid film were captured using a digital video camera with a macro lens for a resolution of about 8.2 microns/pixel. Cross-sectional data at 68 annular flow conditions were obtained. The observations of the liquid film between waves indicated that the film thickness was relatively insensitive to both gas and liquid flow in the annular regime, confirming film thickness measurements reported elsewhere. In addition, the structure of waves changes significantly from wavy-annular, where peaked or cresting waves dominate, to fully annular, where the waves are much more turbulent and unstructured. The wave height decreases with increased gas flow and is relatively insensitive to increased liquid flow in the annular regime. The entrainment of gas in the liquid by the waves is very apparent from these images. Although the precise entrainment mechanisms are not entirely clear, a viable folding action mechanism is proposed. The visualization results will be discussed in relation to both conceptual and computational annular flow modeling.
Experimental and Numerical Studies of Laser-Assisted Drilling Processes
Authors: Jen Tien-Chien , Chen Yau-Min , Tuchowski Fern
Published: March 2009

The application of lasers in manufacturing has gained considerable attention recently. The aim of this study is to develop an innovative laser-assisted drilling process through an innovative tool design. Predictive thermal optimization tools will also be developed which will greatly extend the tool life and the keep the machine down time to a minimum. An experimental investigation of a laser assisted drilling process was conducted in this study. Carbon steel (0.1% Carbon content) was used as the ablating material and a CW CO2 laser was employed with the beam formed into a ring shape. Finite Element Method was also used for numerical simulation of the process. Comparison between experimental and numerical results indicates good qualitative agreement between theory and experiment within the limits of the (rather large) uncertainty with which material properties are known to date.
A Mechanistic Model for Predicting Heat and Mass Transfer in Vertical Two-Phase Flow
Authors: Shirazi Siamack A. , Al-Adsani Ebrahin , Shadley John R. , Rybicki Edmund F.
Published: March 2009

The mass transfer coefficient plays an important role in predicting corrosion rates. Using similarities between heat and mass transfer mechanisms, a mechanistic model is proposed to predict heat and mass transfer coefficients for two-phase flow in vertical pipes. The mechanistic model is evaluated by using water-air heat transfer experimental data obtained from the literature. The mechanistic model is also compared with commonly used empirical correlations. In comparison with available heat transfer correlations, the mechanistic model performs very well for vertical annular flow, bubbly flow and slug or intermittent flow that were considered. The mechanistic model is based on physics of two-phase flow and thus is expected to be more general than empirical correlations.
Film Boiling Heat Transfer on a High Temperature Sphere in Nanofluid
Authors: Park Hyun Sun , Shiferaw Dereje , Sehgal Bal Raj , Kim Do Kyung , Muhammed Mamoun
Published: March 2009

Quenching experiments of a high temperature sphere in Al2O3 nanofluids are conducted to investigate the characteristics of film boiling and compared to those in pure water tests. One stainless steel sphere of 10 mm in diameter at the initial temperatures of 1000∼1400 K was tested in the nanofluids of the volume concentrations from 5 to 20% and the degrees of subcooling from 20 to 80 K. The test results show that film boiling heat fluxes and heat transfer rates in nanofluids were lower than those in pure water. The differences of the film boiling heat transfer rates between pure water and nanofluids become larger when the liquid subcooling decreases. Those results suggest that the presence of nanoparticles in liquid enhances vaporization process during the film boiling. The effects of nanoparticle concentrations of more than 5 vol. % on film boiling appear to be insignificant. However, the minimum heat fluxes tend to decrease when the concentration increases. Direct quenching without film boiling was repeatedly observed when an unwashed sphere was employed for quenching tests in nanofluids. It suggests that nanoparticle deposition on the sphere surface prevents the sphere from forming film around the sphere, which consequently promotes the rapid quenching of the hot sphere.
Integrated Thermomechanical Design and Optimization of BGA Packages Using Genetic Algorithm
Authors: Hadim Hamid A. , Suwa Tohru
Published: March 2009

A new multidisciplinary design and optimization methodology in electronics packaging is presented. A genetic algorithm combined with multi-disciplinary design and multi-physics analysis tools are used to optimize key design parameters. This methodology is developed to improve the electronic package design process by performing multidisciplinary design and optimization at an early design stage. To demonstrate its capability, the methodology is applied to a Ball Grid Array (BGA) package design. Multidisciplinary criteria including thermal, thermal strain, electromagnetic leakage, and cost are optimized simultaneously. A simplified routability analysis criterion is treated as a constraint. The genetic algorithm is used for systematic design optimization while reducing the total computational time. The present methodology can be applied to any electronics product design at any packaging level from the chip level to the system level.
Development and Experimental Validation of an Exergy-Based Computational Tool for Data Center Thermal Management
Authors: Shah Amip J. , Carey Van P. , Bash Cullen E. , Patel Chandrakant D.
Published: March 2009

The recent miniaturization of electronic devices and compaction of computer systems will soon lead to data centers with power densities of the order of 300 W/ft2. At these levels, traditional thermal management techniques are unlikely to suffice. To enable the dynamic smart cooling systems necessary for future data centers, an exergetic approach based on the second law of thermodynamics has recently been proposed. However, no experimental data related to this concept is currently available. This paper discusses the development and subsequent validation of an exergy-based computer model at an instrumented data center in Palo Alto, California. The study finds that when appropriately calibrated, such a computational tool can successfully predict information about local and global thermal performance that cannot be perceived intuitively from traditional design methods. Further development of the concept has promising potential for efficient data center thermal management.
Numerical Simulation of Transport in Optical Fiber Drawing With Core-Cladding Structure
Authors: Chen Chunming , Jaluria Yogesh
Published: March 2009

Optical fibers are typically heated and drawn from silica preforms, which usually consist of two concentric cylinders called the core and the cladding, in a high-temperature furnace. For optical communication purpose, the core always has a higher refractive index than the cladding. In order to investigate the effect of core-cladding structure on the optical fiber drawing, a numerical model has been developed in this work. Axisymmetric flows of a double-layer glass and aiding purge gas in a concentric cylindrical furnace are considered. The thermal and momentum transport in both glass layers and gas are coupled at the interface boundaries. The neck-down profile is generated using an iterative scheme. The zonal method is applied to model the radiation transfer in the glass preform and the gas. Coordinate transformations are used to convert complex domains into cylinders. Stream function, vorticity and energy equations for the core, the cladding and the purge gas are solved by finite different methods using a false transient method coupled with an alternating direction implicit (ADI) method. A second order differencing scheme is used for discretization. The numerical results are validated by comparing with experimental and numerical results available in the literature.
Computing Flow in a Solar Chimney Plant Subject to Atmospheric Winds
Authors: Serag-Eldin M. A.
Published: March 2009

The paper presents a computational model for predicting the effect of atmospheric winds on performance of solar chimneys. It comprises governing partial differential equations expressing conservation of mass, energy and balance of momentum in addition to a two equation model of turbulence to compute the detailed flow pattern in the neighborhood of the solar chimney plant. The model is applied to compute the flow field in a small exemplary Solar chimney plant, subject to wind speeds ranging from weak to strong. The predicted results are analyzed and reveal that wind effects are definitely not negligible, although this is generally assumed in Solar Chimney modeling. The analysis reveals a total degradation of performance with strong winds, and considerable degradation even with weak winds unless the collector inlet height is relatively low.
Multiphase Particle-in-Cell Simulations of Dense-Phase Flows in Cyclone Separators
Authors: Snider Dale , Williams Ken , Johnson Robert A.
Published: March 2009

An Eulerian-Lagrangian numerical method is used to simulate the cyclone separator experiment by Hoffmann [1] which is operated under low solid loadings. Comparisons are made with data from for overall separation efficiency and on a size-distribution basis, i.e., ‘cut-grade’. The Arena-flow computational approach is a transient, three-dimensional multiphase particle-in-cell (MP-PIC) numerical method where the dynamics of both the continuum fluid and millions of discrete particle ‘clouds’ are solved using Eulerian and Lagrangian representations, respectively. The Arena-flow software allows for any distribution of particle types, sizes, and density. The three-dimensional transient simulations show excellent agreement with measured data which have cyclone efficiencies on the order of 85%. The CFD analysis reveal details that cannot be experimentally measured, such as internal particle size segregation, wall effects, vortex entrainment, particle-to-particle interactions and agglomeration.
Numerical Study of an Evaporating Meniscus on a Moving Heated Surface
Authors: Mukherjee Abhijit , Kandlikar Satish G.
Published: March 2009

The present study is performed to numerically analyze an evaporating meniscus on a moving heated surface. This phenomenon is similar to the one observed at the base of a vapor bubble during nucleate boiling. The complete Navier-Stokes equations along with continuity and energy equations are solved. The liquid vapor interface is captured using the level set technique. A column of liquid is placed between two parallel plates with an inlet for water at the top to feed the meniscus. The location of water inlet at the top is kept fixed and the bottom wall is imparted with a velocity. Calculations are done in two-dimensions with a fixed distance between the plates. The main objective is to study the velocity and temperature fields inside the meniscus and calculate the wall heat transfer. The results show that the wall velocity creates a circulation near the meniscus base causing increased wall heat transfer as compared to a stationary meniscus. The local wall heat transfer is found to vary significantly along the meniscus base, the highest being near the advancing contact line.
Application of Computational Fluid Dynamics: Fire Safety Awareness for Gas Station in Dense Urban Areas With Wind Effects
Authors: Chow W. K.
Published: March 2009

Consequent to a big gas station fire in Macau and another recent one affected by a nearby explosion in a fireworks factory in China, there are concerns on the fire safety issues of gas stations in urban areas. Those two incidents were not too terrible but the situation would be much worse if there was strong wind, especially in a dense urban area where buildings are closely built together. There are many gas stations built within residential areas in Hong Kong. Wind-induced air movement is a transient phenomenon which depends not only on the wind speeds measured at some designated sites, but is also strongly affected by the surrounding environment. For a gas station located adjacent to a taller building, turbulent effects due to incident wind fields would be important. This is not just a safety problem of the gas station, nor for any single building. A risk management system should be worked out by the Authority in the estate district, suburb, or even the whole city. The problem must be considered carefully for cities with dense population and numerous highrise buildings. Computational fluid dynamics (CFD) is a suitable tool for hazard assessment on the spreading of smoke and heat. In this paper, the wind-induced air flow in a gas station fire next to a building was studied by CFD. The CFD simulator selected is the Fire Dynamics Simulator (FDS) version 3.01. Acoustic filtering technique was applied to remove the flow with high Mach number and large-eddy simulations (LES) were applied to model smaller turbulent scales. Different scenarios on the gas station position, building height and distance away from a vertical wall of the building were simulated. Wind effect was simulated by taking the incident air flow as a parabolic boundary layer. The results are very useful for working out risk management in case of accidents. Note that smoke or even flame will spread by following the wind-induced air motion.
On Evaluating Static Smoke Exhaust System in an Atrium
Authors: Yi L. , Huo R. , Li Y. Z. , Chow W. K. , Fong N. K.
Published: March 2009

Many atria are built in the Far East. Fire Safety is a concern and providing smoke management systems in atria is essential. For tall atria having difficulties to allocate space for air ductwork and fans of a dynamic smoke exhaust system, a smoke exhaust system with a ceiling vent is provided. The performance of the system should be evaluated and a two-layer zone model has been designed for such propose. The smoke layer temperature and interface height for a static smoke exhaust system in a tall space will be predicted. Based on the empirical formula derived from the entrainment rate of an axisymmetric plume and flow rate at a vent, a simplified calculation procedure of a static smoke exhaust in an atrium fire is proposed. Experiments were carried out at a full-scale burning facility of 27 m high, the USTC/PolyU Atrium, for verifying the results. It is found that the predicted smoke layer temperature and interface height agreed well with the experimental results. Therefore, the procedure is recommended to the authority as a tool in evaluating the performance of static smoke exhaust systems.
Analytical Models for the Systematic Errors of Differential Scanning Calorimetry Instruments
Authors: Sabau Adrian S. , Porter Wallace D.
Published: March 2009

Differential Scanning Calorimetry (DSC) measurements are routinely used to determine enthalpies of phase change, phase transition temperatures, glass transition temperatures, and heat capacities. In order to obtain data on the amount of phases during phase change, time-temperature lags, which are inherent to the measurement process, must be estimated through a computational analysis. An analytical model is proposed for the systematic error of the instrument. Numerical simulation results are compared against experimental data obtained at different heating and cooling rates.
Structure of the Rotor Tip Flow in a Highly-Loaded Single-Stage Axial-Flow Pump Approaching Stall: Part I — Breakdown of the Tip-Clearance Vortex
Authors: Schrapp H. , Stark U. , Goltz I. , Kosyna G. , Bross S.
Published: March 2009

Moderate cavitation was used to visualize the tip clearance vortex in a highly-loaded single-stage axial-flow pump. Two different techniques were utilized to produce photographs and videos. From these it was found that for flow rates lower than design an initially well defined clearance vortex undergoes spiral-type vortex breakdown. This result was theoretically confirmed in an approximate manner by solving the Bragg and Hawthorne equation for an isolated vortex with a measured casingwall pressure distribution as a prescribed boundary condition.
Hot Wire Measurements Around a CD Airfoil in an Open-Jet Anechoic Wind Tunnel
Authors: Moreau S. , Neal D. , Foss J.
Published: March 2009

The aeroacoustic measurements in the ECL large anechoic wind tunnel, which originally focused on the wall pressure distribution and the far field acoustic pressure are extended to velocity measurements by hot-wire probes in the nozzle jet and in the vicinity of the subject airfoil. The present work focuses on the exit plane of the wind tunnel nozzle upstream of the test airfoil and in the LES computational domain that is embedded in the potential core around the airfoil mock-up at mid span. The inlet measurements by a single hot-wire probe provide some insight on free-stream turbulence intensity upstream of the profile. The X-array measurements on the upper and lower LES boundaries show the overall deflection of the jet potential core by the cambered airfoil. These are compared to the Fluent RANS predictions. The X-array measurements in the airfoil wake provide information on the development of the airfoil boundary layer and the resulting wake after separation. The measured wake velocity defect has been compared with both the RANS and LES predictions.
Characterization of Water Mist Sprays Using a Phase-Doppler-Particle-Analyzer and an Iso-Kinetic Sampling Probe
Authors: Ditch Benjamin , Yu Hong-Zeng
Published: March 2009

A Phase-Doppler-Particle-Analyzer (PDPA) was used to screen candidate water mist nozzles for use in a scaling validation aimed to allow scaled-down testing of water mist systems. A custom-designed iso-kinetic sampling probe (IKSP) was developed to independently measure water mist fluxes at the same locations where PDPA measurements were made. Measurements were taken at two elevations in selected full-cone water mist sprays. The water drop size was found to increase with radial distance from the spray centerline, while the mean drop velocity and drop concentration decrease with radial distance. Gross drop size distributions of water mist sprays were derived from local drop size distributions and water fluxes measured in two spray cross sections. It was found that, for the water mist sprays investigated in this study, both Rosin-Rammler and log-normal distributions are required to correlate the entire drop size spectrum. In general, the agreement between the mist fluxes measured with the PDPA and iso-kinetic sampling was within 7% near the spray centerline. The selected nozzles show appropriate intended scaling in terms of the drop size, nozzle discharge pressure, and water discharge rate.
Decontamination Using Foams: A Brief Review of 10 Years French Experience
Authors: Fournel B. , Faure S. , Pouvreau J. , Dame C. , Poulain S.
Published: March 2009

This paper is an overview of fundamental studies and large scale achievements of the foam decontamination technique in the frame of a ten years research program conducted in the CEA. Main aspects of foam feature (hydrodynamic, stability, chemical composition) are developped. Industrial applications gave the opportunity to experiment many ways to use foam: spraying, circulating, static foams. Economical benefits of the technique are qualitatively assessed and future developments are pointed out.
Treatment and Volume Reduction of Transuranic Waste at the Los Alamos National Laboratory Plutonium Facility
Authors: Balkey J. J. , Ramsey S. S. , Wieneke R. E.
Published: March 2009

Los Alamos National Laboratory (LANL) is one of two design laboratories in the United States Department of Energy’s (DOE) weapons complex, with over 60 years of experience in handling radioactive materials and, consequently, in radioactive waste management. The focus for actinide research and development is the Plutonium Facility, which has been in operation since 1978. The Nuclear Materials Technology (NMT) Division is responsible for operating the Plutonium Facility. It has a dedicated group of personnel who manage radioactive and hazardous waste, and address environmental regulations. Waste from operations with radioactive materials inside glovebox lines in the Plutonium Facility is packaged for disposal in the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. This waste is subject to a prescriptive certification program and is expensive to dispose of. Because the Plutonium Facility generates approximately 140 cubic meters of transuranic (TRU) waste each year, this significant financial burden effectively reduces the funds available to conduct research. To cut waste disposal costs, the NMT Division is making a considerable effort to identify and fund implementation of treatment and size-reduction processes. This study looks at both the effectiveness and probability of successful implementation. The waste management group’s waste minimization specialist has used waste generation information to identify the two largest TRU waste streams: combustible solids would benefit from size reduction, and nonactinide metals can be decontaminated. To reduce the size of combustible solids (polyethylene bottles and rubber hose), an industrial-model granulator, which was purchased for the head end of a molten salt oxidation process, is being adapted. This waste stream can be reduced by about 30% without affecting the ability to perform nuclear material assay. For glovebox decontamination, electrolytic decontamination techniques previously developed will also work on metals (tubing, tools, and equipment). Reducing the TRU levels to low-level contamination will allow onsite disposal, significantly reducing disposal costs (by approximately an order of magnitude). Several other technologies that were developed to address environmental regulatory concerns will also result in modest waste minimization and are in various states of installation and testing; they are vitrification for aqueous TRU waste, pyrolysis for the destruction of mixed waste, and distillation and recycle for nitric acid and trichloroethylene. The successful implementation and coordination of waste minimization and treatment technologies is resulting in cost savings from waste reduction and avoidance for the NMT Division.
The 3D Dynamic Simulation on the RSR and the Shielding Concrete Dismantling Process of the KRR-2
Authors: Kim Sung-Kyun , Jung Un-Soo , Lee Kune-Woo , Park Jin-Ho
Published: March 2009

The 3D simulations of the shielding concrete and the Rotary Specimen Rack (RSR) in the Korea Research Reactor-1&2 (KRR-1&2) were carried out in present work. Four main dismantling processes, which are the removal of the RSR, reactor core region, beam tube, and thermal column and activated concrete, were selected for the graphic simulation by the consideration of the activation, worker training, work difficulty and so on. On the basis of those, we constructed their 3D CAD models, selected proper dismantling technologies, and reviewed their dismantling processes. In this study, the 3D simulation results of the shielding concrete and the RSR among main components are also presented and discussed.
Free-Release Monitoring Equipment in the UK Nuclear Power Industry
Authors: Pottinger M. P. , Orr C. H.
Published: March 2009

In the nuclear power industry, many techniques are used to confirm that items are suitable for free-release. These techniques usually involve monitoring of the items with at least one type of radiometric instrument, to ensure that no significant quantity of man-made radioactivity is present. These monitoring techniques depend on the stage in the clearance process, the application and the size of the article being monitored. The UK Radioactive Substances Act has a Substances of Low Activity (SoLA) exemption which allows for articles and waste that have a man-made radioactive content less than 0.4 Bq g−1, to be classified as non-radioactive and be discharged from site in similar fashion to conventional wastes. Identifying whether the waste meets the criteria is technically challenging due to the low level of this exemption. Consequently the detection limits of most common portable radiation protection instrumentation is higher than this level. Historically portable alpha and beta contamination instruments are used as part of the clearance process; these are reasonably effective at monitoring the surface of an object for the presence of radioactivity, but far less so for bags of waste where alpha and beta emissions are easily absorbed within the waste. Portable gamma only contamination instruments have proved effective where some contaminants emit gamma radiation. However even these instruments have some difficulty in confirming that an article is “free” from man-made radioactivity where the mass of the article is below a critical mass. In this industry, the radioactive fingerprint will typically include an easily detectable gamma emitting radionuclide such as 60Co, or 137Cs, which may be used as a tracer for other radionuclides which cannot be easily detected with such an instrument. Installed clearance (bag) monitors are very effective where the user has a good knowledge of the radioactive fingerprint, and where there are significant (more than 10%) gamma emitting radionuclides in the fingerprint. They are ineffective where pure alpha and beta emitters dominate the radioactive fingerprint. These monitors are capable of monitoring to 1/10 of the SoLA exemption level for 60Co, with a small variation in response across the volume of the measurement chamber. Inevitably these instruments are also sensitive to NORM, so a good knowledge of NORM activity concentrations is each waste stream is required for adequate compensation. Vehicle monitors are useful for reassurance monitoring, although due to the variable nature of each waste consignment and the high background count rate, their high detection limit means they are not suitable as the sole means of free release monitoring.
Direct Push Technology and Application to Vertical Profiling of Hydraulic Conductivity in Unconsolidated Formations
Authors: McCall Wesley , Christy Thomas M. , Butler James J.
Published: March 2009

Direct push (DP) methods provide a cost-effective alternative to conventional rotary drilling for investigations in unconsolidated formations. DP methods are commonly used for sampling soil gas, soil and groundwater; installing small-diameter monitoring wells; electrical logging; cone penetration testing; and standard penetration tests. Most recently, DP methods and equipment for vertical profiling of formation hydraulic conductivity (K) have been developed. Knowledge of the vertical and lateral variations in K is integral to understanding contaminant migration and, therefore, essential to designing an adequate and effective remediation system. DP-installed groundwater sampling tools may be used to access discrete intervals of the formation to conduct pneumatic slug tests. A small-diameter (38mm OD) single tube protected screen device allows the investigator to access one depth interval per advancement. Alternatively, a larger diameter (54mm OD) dual-tube groundwater profiling system may be used to access the formation at multiple depths during a single advancement. Once the appropriate tool is installed and developed, a pneumatic manifold is installed on the top of the DP rod string. The manifold includes the valving, regulator, and pressure gauge needed for pneumatic slug testing. A small-diameter pressure transducer is inserted via an airtight fitting in the pneumatic manifold, and a data-acquisition device connected to a laptop computer enables the slug test data to be acquired, displayed, and saved for analysis. Conventional data analysis methods can then be used to calculate the K value from the test data. A simple correction for tube diameter has been developed for slug tests in highly permeable aquifers. The pneumatic slug testing technique combined with DP-installed tools provides a cost-effective method for vertical profiling of K. Field comparison of this method to slug tests in conventional monitoring wells verified that this approach provides accurate K values. Use of this new approach can provide data on three-dimensional variations in hydraulic conductivity at a level of detail that has not previously been available. This will improve understanding of contaminant migration and the efficiency and quality of remedial system design, and ultimately, should lead to significant cost reductions.
Studies on Spent Fuel Alterations During Storage and Radiolysis Effects on Corrosion Behaviour Using Alpha-Doped UO2
Authors: Rondinella V. V. , Wiss T. , Hiernaut J.-P. , Cobos J.
Published: March 2009

UO2 containing different fractions of short-lived alpha-emitters, the so-called alpha-doped UO2 simulates the level of activity of spent fuel after different storage times, and can be used to study the effects of radiolysis on the corrosion behaviour of aged spent fuel exposed to groundwater in a geologic repository. Furthermore, the integral over time of the alpha-decay in alpha-doped UO2 can simulate the decay damage accumulated in spent fuel during storage. This allows investigating property modifications occurring to the fuel during storage periods of interest (e.g. in view of spent fuel retrieval or in view of final disposal) within a laboratory-acceptable timescale. Periodical measurements of lattice parameter are performed on high activity alpha-doped UO2 to investigate the build-up of radiation damage and evaluate possible dose rate effects. Additionally, annealing tests combined with He-release measurements using a Knudsen cell and with microstructure examination using TEM are performed to establish a correlation among the annealing of damage in the microstructure (mainly characterized by dislocation loops) and the release behaviour of He. The effects on the microstructure due to the accumulation of He and α-decay damage are of interest as they may considerably affect the mechanical integrity of the fuel rods, by causing e.g. swelling or cracking in the fuel and/or overpressurization of the cladding. Alpha-doped UO2 with specific activities spanning over three orders of magnitude and undoped UO2 were used in static leaching experiments at room temperature in deionized water under nominally anoxic conditions. Under these experimental conditions (single effect studies) a clear dissolution enhancing effect of alpha-radiolysis was observed coupled with the establishment of higher redox potential due to the radiolytic process. An alpha-activity dependence of the dissolution behaviour was observed.
Studies of the Fundamental Chemistry of Hanford Tank Sludges
Authors: Lumetta Gregg J. , Rapko Brian M. , Cho Herman M.
Published: March 2009

The U.S. Department of Energy has embarked on an effort to retrieve, immobilize, and dispose of the 2.1 × 105 m3 of radioactive tank wastes that were generated during weapons production and other operations at the Hanford Site in Washington State. One of the major challenges associated with this effort is the processing of the 4.2 × 104 m3 of high-level waste sludges. These sludges consist of a complex mixture of amorphous and crystalline mineral phases. The current plan for processing the sludge solids consists of leaching with aqueous NaOH, washing out the NaOH and dissolved components, then vitrifying the solids in borosilicate glass. The purpose of the NaOH leaching step is to remove components such as Al, Cr, and P that can lead to the production of an unacceptable quantity of high-level waste glass. In this paper, we will discuss the chemistry underlying the leaching and washing processes, focusing on the specific mineral phases present in the sludge solids and how these phases respond to the leaching process. The chemical phases present in the Hanford tank sludge solids have been identified through microscopy coupled with electron diffraction and through powder X-ray diffraction. We have also recently been applying nuclear magnetic resonance spectroscopy to characterize chemical species in tank sludge solids. Numerous chemical species have been identified including the aluminum oxy/hydroxides gibbsite and boehmite, aluminosilicates, iron oxy/hydroxides, and mixed Cr/Fe oxyhydroxides. Identification of these phases has led to a more fundamental understanding of the behavior of the various sludge components during leaching; in turn, this understanding will allow for improved process flow sheets. For example, we have shown that certain tank sludges are high in boehmite, Υ-AIOOH. This mineral phase is much more refractory than other AI phases such as gibbsite. Thus, more severe leaching conditions (e.g., increased temperature, NaOH concentration, and leaching duration) are required to remove AI from wastes high in boehmite.
EDF Decommissioning Programme: A Global Commitment to a Sustainable Development
Authors: Grenouillet Jean-Jacques
Published: March 2009

Nowadays, decommissioning of nuclear power plants has become a key issue for nuclear industry in Europe. The phasing out of nuclear energy in Germany, Belgium and Sweden, as well as the early closure of nuclear units in applicant countries in the frame of EU enlargement, has largely contributed to consider decommissioning as the next challenge to face. The situation is slightly different in France where nuclear energy is still considered as a safe, cost-effective and environment friendly energy source. Electricite´ de France (EDF) is working on the development of a new generation of reactor to replace the existing one and erection of a new nuclear power plant could start in the next few years. Nevertheless, to achieve this objective, it will be necessary to get the support of political decision-makers and the acceptance of public opinion. Due to the growing concern of these stakeholders for environmental issues, their support can only be obtained if it is possible to demonstrate that nuclear energy industry will not leave behind unsolved issues that will be a burden to the next generations. In this context decommissioning of the first generation of EDF NPPs constitutes a prerequisite for the erection of a new type of nuclear power plant. This paper will present the programme defined by EDF for the decommissioning of its nine already shutdown reactors (Fig. 1). The reasons of the recent evolution of EDF decommissioning strategy will be explained and the key issues that will contribute to the successful implementation of this programme will be addressed. Finally, what has been achieved on sites so far and major planned activities will be described.
The Management of Historic Intermediate Level Radioactive Waste in the United Kingdom
Authors: Horsley David , McKirdy Bruce
Published: March 2009

Nirex is the organisation responsible for long-term radioactive waste management in the UK. Our Mission is to provide the UK with safe, environmentally sound and publicly acceptable options for the long-term management of radioactive materials. The United Kingdom has a significant legacy of long-lived intermediate level radioactive waste. This has arisen from 50 years of investigation and exploitation of nuclear technology. Some of the waste is stored in old facilities that do not provide the standards of containment that would be incorporated in modern facilities. Also the risk to people and to the environment from the inventory in these facilities will increase with time as the structures age and degrade, increasing the chance of containment failure. There is, therefore, a need to retrieve this raw waste and process and package it to make it demonstrably safe for continued storage, pending a decision on disposal of radioactive waste. This packaging should, as far as is practicable, be compatible with the UK long-term waste management strategy. Nirex has developed its Phased Disposal Concept for intermediate and low-level radioactive waste. Based on that concept, Nirex has developed waste package specifications and carries out assessments of waste packaging proposals. For legacy wastes it may not always practicable to demonstrate full compliance with all Nirex disposal criteria. This paper describes an approach, agreed between Nirex and BNFL, for managing these wastes. The proposed approach takes account of long-term waste management issues whilst recognising the need for timely improvement of storage conditions.
Removal of Actinides and Other Radioactive Metal Ions From Water Systems
Authors: Watson J. H. P. , Ellwood D. C. , Lidzey R. G.
Published: March 2009

In previous work the adsorption of a number of radioactive ions from solution by a strongly-magnetic iron sulfide material has been studied. The material was produced by sulfate-reducing bacteria in a novel bioreactor. The uptake is rapid and the loading on the adsorbent is high due to the high surface area of the adsorbent and because many of the ions are chemisorbed. Following the success of the biologically-generated material, Lidzey at Bio Separation Ltd was able to produce an iron sulfide material; studies at the University of Southampton reveal that it has the tochilinite structure which has similar adsorption properties for cations, but not anions, as the biologically-generated material but the Lidzey material is considerably cheaper to produce. Tochilinite is a layered metal hydroxide/sulfide composite. The composition of tochilinite ranges around 2Fe1-xS. {1.7Fe(OH)2}. In nature, these materials also have Mg0.7Al 0.3 replacing Fe in the hydroxide layer. By also precipitating magnetite, Fe3O4, together with the tochilinite Lidzey has made the adsorbent strongly magnetic. This paper presents individual results on the adsorption of 137Cs, 59Fe, 60Co, 106Ru, 110mAg, 51Cr, 54Mn, 203Hg, 109Cd, 90Sr, 239Pu and 241Am. Using 0.5g.l−l of the adsorbent the reduced the activity in solutions from 1190 Bq.ml−1 to <530 Bq.ml−1 after 1 h and to 340 Bq.ml−1 after 24 h. with 51Cr and 203Hg being responsible for 270 Bq.ml−1 of the total. For the decontamination of water streams containing dissolved radioactive isotopes the method proposed is to add the adsorbent and after a suitable residence time to extract the contaminated adsorbent using high gradient magnetic separation. In this method a slurry containing the particles to be separated are passed through a matrix of fine ferromagnetic wires magnetised to magnetic saturation by an externally applied magnetic field usually 5 Tesla. The particles to be separated are captured on the matrix, the decontaminated liquid passing through. The matrix is removed from the field and at the same time a clean matrix is inserted. The captured material recovered outside the magnetic field as a thick slurry and he cycle is repeated. These magnetic separation systems are in use throughout the world and will process up to 500m3.h−1.
Microchannels and Minichannels: History, Terminology, Classification and Current Research Needs
Authors: Kandlikar Satish G.
Published: March 2009

Microchannels and Minichannels are found in many biological systems providing very high heat and mass transfer rates in organs such as the brain, lung, liver and kidney. Many high flux cooling applications are effectively utilizing their high heat transfer capabilities of these channels. A brief overview of the historical perspective and some of the issues that need to be addressed with microchannels and Minichannels are presented in this paper.
Mini- and Microchannel Research in Sweden
Authors: Palm Bjo¨rn
Published: March 2009

The purpose of the present paper is to present research and development within the area of mini- and micro channels in Sweden. A review is made of the historical development of highly compact heat exchangers within the country, starting with plate heat exchangers. The main focus is on the research performed at the Royal Institute of Technology, where mini-channel research has been going on since more than ten years. Single-phase flow as well as two-phase flow is treated, both in single channels and in full-size heat exchangers with multiple parallel channels.
Heat Transfer Mechanisms During Flow Boiling in Microchannels
Authors: Kandlikar Satish G.
Published: March 2009

The forces due to surface tension, inertia, and momentum change during evaporation in microchannel govern the two-phase flow patterns and the heat transfer characteristics during flow boiling. These forces are analyzed in this paper, and two new non-dimensional groups, K1 and K2, relevant to flow boiling phenomenon are derived. These groups are able to represent some of the key flow boiling characteristics, including the CHF. The small hydraulic dimensions of microchannel flow passages present a large frictional pressure drop in single-phase and two-phase flows. In order to keep the pressure drop within limits, the channel lengths are generally shorter and the mass fluxes are generally lower than those with conventional channels (Dh>3 mm). The resulting lower mass fluxes, coupled with small Dh, lead to Reynolds numbers in the range 100–1000. Such low Reynolds numbers are rarely employed for flow boiling in conventional channels. In these low Reynolds number flows, nucleate boiling systematically emerges as the dominant mode of heat transfer. Aided by strong evaporation rates, the bubbles nucleating on the wall grow quickly and fill the entire channel. The contact line between the bubble base and the channel wall surface now becomes the entire perimeter at both ends of the vapor slug. Evaporation occurs at the moving contact line of the expanding vapor slug as well as over the channel wall covered with a thin liquid film surrounding the vapor core. The usual nucleate boiling heat transfer mechanisms, including liquid film evaporation and transient heat conduction in the liquid adjacent to the contact line region, play an important role. The liquid film under the large vapor slug evaporates completely at downstream locations thus presenting a dryout condition periodically with the passage of each large vapor slug. The flow boiling correlation by Kandlikar [1, 2] with (i) the nucleate boiling dominant region equation, and (ii) the laminar flow equation for single-phase all-liquid flow heat transfer coefficient hLO was successful in correlating the available R-134a data for parallel microchannels of 190 μm hydraulic diameter.