bluuebunny/crossref_metadata_2025 huggingface dataset:
2D/3D Oxide/Oxide Ceramic Matrix Composites Life Prediction Methods: Virtual Characterization of Mechanical Properties, and Virtual Testing of Structural Component
Authors: Abdi Frank , Thompson Dan
Published: March 2009

Progressive failure analysis (PFA) method was employed to investigate the material and sub-element performances made of Alumina/Alumina (N720/A) ceramic matrix composites (CMC). A numerical material characterization was performed to derive the composite constituent properties based on the tested in-plane tensile and compressive properties of the 2D CMC. The derived constituent properties were then applied to the simulations of the 2D composite other properties including in-plane shear, inter-laminar shear and tension, in-plane bending and biaxial tension. The 3D composite in-plane and inter-laminar tensile behaviors were also predicted using the constituent properties. Finally, the simulation procedure was applied to the life prediction of a sub-element fabricated from the 2D N720/A CMC. The simulation results agreed well with the Siemens test data, which indicates the constituent properties can account for their realistic behaviors in the N720/A CMC. In addition, simulations also provided detailed information of stress fields, damage development and failure mechanisms involved in each specimen.
The Use of CFD to Generate Heat Transfer Boundary Conditions for a Rotor-Stator Cavity in a Compressor Drum Thermal Model
Authors: Saunders K. , Alizadeh S. , Lewis L. V. , Provins J.
Published: March 2009

In an engine design process, thermo-mechanical analyses of compressor drums and casings are undertaken, to predict component temperatures and displacements, which are ultimately used for material selection, blade clearance control and lifing of components. The thermal boundary conditions are sourced from a small number of standard flow field and heat transfer solutions, leading to a reliance on engine thermocouple tests to provide calibration factors on the boundary conditions, which with changes in inlet flows and cavity geometry from the tested arrangements are unproven, limiting the ability to readacross the test information into new designs. Given that the thermal boundary conditions in compressor drum and casing components are largely driven by complex flow physics, in the absence of suitable test information, CFD methods can be used to provide boundary specification of the thermo-mechanical problem, incorporating the complex physics involved. Without the insight of the flow field solution in complex flow regions, specification of the boundary conditions is rather subjective and mostly based on intuition. This study shows the use of CFD to provide the boundary conditions for the rotor-stator cavity at the front of an IP compressor drum. The CFD is run adiabatically and through a set of unit heat transfer cases on separate sections of the cavity wall, at key points in the flight cycle. The analyses provide appropriately characterized thermal boundary conditions (specifically heat transfer coefficients and adiabatic wall temperatures) that are transferred into the thermo-mechanical model, which can then be run through a wide range of cycles without the need for further CFD calculations.
Evaluation of the Theta (Θ) Projection Technique for Estimating the Remaining Creep Life of GTD-111DS Turbine Blades
Authors: Bagnoli K. E. , Cater-Cyker Z. D. , Budiman B. S.
Published: March 2009

Remaining life estimates for hot section turbine components often involves the use of creep models based on parametric extrapolations of short-term stress rupture tests. For the assessment of components such as gas turbine blades fabricated from nickel based superalloys, strain based approaches may be more useful since life is often evaluated in terms of the time to reach a critical strain limit. In the case of GTD-111DS, General Electric (GE) recommends a retirement limit in the range of 0.5%–1% strain at any point in the airfoil. Tertiary models such as the MPC Omega method, which has gained some popularity in the refining industry, are generally adequate for predicting rupture or retirement times in situations where life is dominated by secondary/tertiary stage creep. However, a constitutive model that describes the full creep curve is needed to adequately evaluate life for highly creep resistant alloys such as GTD-111DS, where a significant portion of service life is consumed with the initial small increments of strain. In this paper, the Theta (Θ) projection technique is used to analyze the creep behavior of GTD-111DS. The statistical variability of extrapolating short term creep tests to actual service conditions using the Θ model is reviewed, and use of the model is discussed in relation to evaluating the life of GTD-111DS turbine blades.
Some Aerodynamic Problems of Aircraft Engines: Fifty Years After
Authors: Greitzer Edward M.
Published: March 2009

Problems of high technological interest, for example the development of gas turbine engines, span disciplinary boundaries. Collaboration is critical in advancing the technology, but it has been less a factor in gas turbine research. In this paper it is proposed that step changes in gas turbine performance can emerge from such collaborative endeavors. In these, success depends on the development of integrated teams with the appropriate range of skills. This is well known in product development, but it is less familiar, and less subscribed to, in the research community. Case histories of two projects are given to illustrate the point: the development of the concept of “smart jet engines” and the Silent Aircraft Initiative. In addition to providing the ability to attack multidisciplinary issues discussion is also given about the way in which collaboration can enhance the research process within a single discipline.
Experimental Application of Diesel Particulate Filters to EMD Switcher Locomotives
Authors: Hedrick John C. , Newburry Don , Fritz Steven G. , Smith Brian
Published: March 2009

The use of exhaust aftertreatment technologies may be required to meet the future Tier IV locomotive emissions standards that have been proposed by the US-EPA. Diesel Particulate Filters (DPF) can achieve a high level of particulate matter (PM) emissions reduction, and they are currently being used on all new 2007 on-highway diesel trucks in the United States. In addition, DPFs have been installed on lower power (1500 kW and less) locomotives in Switzerland that are fitted with 4-cycle high speed diesel engines. However, these systems are only now beginning to be sized and demonstrated in a locomotive environment in the United States. Initial testing of the retrofitted DPF system on a 1,125 kW two-stroke, EMD 12-645 Roots-Blown engine powered locomotive achieved an average 80% reduction in Particulate Matter and an average of 30% reduction in Hydrocarbon from the baseline emissions levels. This paper will discuss the background of the “California Emissions Program”, the current and recently proposed EPA emissions standards for locomotives, the Diesel Particulate Filter (DPF) used in the field demonstration, and emission test results.
Study on Characteristics of HCCI Engine Operation for EGR, Equivalence Ratio and Intake Charge Temperature and Pressure While Using Dimethyl Ether
Authors: Shahangian Seyed Navid , Jazayeri Seyed Ali , Bagheri Nader
Published: March 2009

In this paper a single-zone zero-dimensional thermodynamic model, coupled with chemical kinetic equations, has been developed using Visual FORTRAN programming software to predict combustion and performance characteristics of HCCI engines using DME fuel. The model is used to investigate the effects of intake temperature, fuel loading, intake pressure, and exhaust gas recirculation (EGR) on auto-ignition characteristics, optimum combustion phasing, and performance of the HCCI engines. Simultaneous effects of these variables for finding the most appropriate regime of HCCI engine operation, considering knock and misfire boundaries, are also studied.
Reduction of Numerical Parameter Dependencies in Diesel Spray Models
Authors: Abani Neerav , Munnannur Achuth , Reitz Rolf D.
Published: March 2009

Numerical grid and time-step-dependencies of Discrete Droplet Lagrangian spray models are identified. The two main sources of grid-dependency are due to errors in predicting the droplet-gas relative velocity, and errors in describing droplet-droplet collision and coalescence processes. For reducing grid-dependency due to the relative velocity effects, gas jet theory is proposed and applied to model diesel sprays. For the time-step dependency, it is identified that the collision sub-model results in drop size variation in the standard spray model. A proposed spray model based on the gas-jet theory is found to improve the time-step independency also along with the mesh independency. The use of both Eulerian (collision mesh) and Lagrangian (radius of influence) collision models along with gas-jet theory is found to provide mesh-independent results.
Controlling Backfire Using Changes of the Valve Overlap Period for a Hydrogen-Fueled Engine Using an External Mixture
Authors: Huynh T. C. , Kang J. K. , Noh K. C. , Lee Jong T. , Caton J. A.
Published: March 2009

The development of a hydrogen-fueled engine using an external mixture (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease of the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.
Mass Conserving Elastohydrodynamic Piston Lubrication Model With Incorporated Crown Lands
Authors: Duyar Mustafa
Published: March 2009

This paper describes a comprehensive model of Elastohydrodynamic piston lubrication, incorporated the crown lands into solution domain to characterize the effect of crown-liner interactions on piston motion. Elastohydrodynamic Lubrication (EHL) analysis of a piston skirt-liner conjunction is in general a useful methodology for design analysis of pistons. The diameters of piston crown lands are much less than those of skirt and liner for typical piston designs. Therefore crown lands normally do not interact with liner under usual operating conditions and hence most of the researchers exclude crown lands from the EHL analysis and mainly focus on piston skirt. However, under some of the engine operating conditions piston crown lands play important role in the secondary dynamics and tribology aspects of pistons. During the thermodynamic cycle when piston is hot and cylinder liner is relatively colder, piston thermal expansion leads to crown-liner interaction, which necessitates EHL, asperity contact and wear considerations of piston crown along with piston skirt. The simulation methodology for piston EHL analysis uses a mass-conserving algorithm for the finite volume method solution of Reynolds equation, which is coupled to elasticity relations and Greenwood-Tripp asperity contact model. Elrod’s mass conserving algorithm enables to model and analyze partially lubricated piston-liner interface by the input of oil supply and moreover rigorously handles cavitated zones, and takes into account piston ring grooves, piston cut-outs and unlubricated areas due to piston geometry. Results are presented from parametric studies that show comparisons between the analyses of the models with piston skirt lubrication only and piston lubrication, which incorporates the crown lands to the EHL domain.
Effects of Design for Piston Pin and Bearing on State of Bearing Lubrication
Authors: Iwasaki Hideyuki , Higasa Yuuto , Takiguchi Masaaki , Sue Seiichi , Shishido Keitaro
Published: March 2009

We measured the friction of piston pin boss bearings for a gasoline engine to make sure of the state of lubrication. In addition, we checked how the shape of the piston pin as well as that of the pin boss influenced the state of bearing lubrication, which was analyzed according to the FEM calculations of pin and bearing contact pressure. As a result, it was made clear that the state of bearing lubrication sharply deteriorated at an engine speed of 3500 rpm or higher because the deformed pin caused the pin edge to heavily come into contact with the bearing, and a side relief was able to improve the state of lubrication at a high engine speed. We also gave a check to the piston pin for thickness to see how it influenced the state of lubrication, finding that a lighter-weight pin led to the deterioration of lubrication.
Form Honing of Piston Running Surfaces
Authors: Weigmann Uwe-Peter
Published: March 2009

This paper discusses various methods for form machining of cylinder bores. One alternative is to use so-called torque plates. Torque plates are deformation elements with identical or similar deformation properties as the cylinder head together with the cylinder head gasket. With this deformation element, the cylinder block is clamped using the cylinder head bolts during the honing operation. Various designs of torque plates are presented here — torque plates which are already being used for serial production as well as newly developed, production optimised designs. As an alternative to the use of a torque plate, the kinematics of the honing procedure can be controlled. In this form honing method, not only static deformations but also dynamic and thermal deformations can be taken into account while producing the negative form.
Prediction of Combustion Velocities, Indicated-Cycle Pressure in the Closed-Valve Phase and Operating Condition Effects on Performance and Emissions of CNG and Gasoline SI Engines
Authors: Baratta Mirko , Caristo Elena , Catania Andrea E. , Spessa Ezio
Published: March 2009

The simulation of heat release, flame propagation speeds and pollutant formation was carried out in both a turbocharged CNG engine and a multivalve naturally-aspirated bi-fuel engine running on either CNG or gasoline. The predictive tool used for investigation is based on an enhanced fractal geometry concept of the flame front which is able to capture the modulation of turbulent to laminar burning speed ratio throughout the overall combustion phase without introducing flame kernel growth or burn out sub-models. The fractal approach is coupled to a simple refined quasi-dimensional multizone combustion model, which includes specifically developed sub-models for evaluating CO and NO formation, in addition to a CAD procedure to determine the burned-gas front area and radius, as is detaild in [16]. An insight is also given into main features of in-cylinder turbulence modeling, as an easy and effective evaluation of the turbulence intensity is needed for an accurate computation of the turbulent burning speed. The predictive model was applied to a wide range of engine speeds (N = 2000–5500 rpm), loads (bmep = 200–790 kPa for the naturally-aspirated engine, bmep = 200–1400 kPa for the turbocharged one), relative air-fuel ratios (RAFR = 0.80–1.60) and spark advances (SA ranging from 8 deg of retard to 8 deg of advance from MBT), and the obtained results were compared to experimental data. These latter were extracted from measured in-cylinder pressure by an advanced diagnostics technique that was previously developed by the authors. The results confirmed a quite accurate prediction of burning speed even without any kind of tuning, with respect to different currently available fractal as well as non-fractal approaches for the simulation of flame-turbulence interaction. Furthermore, the authors’ computational code showed to be capable of capturing the effects of fuel composition, different combustion-chamber concepts, and operating conditions on engine performance and emissions.
Inline Biodiesel Blending
Authors: Rymsha Steven M.
Published: March 2009

This paper will cover a method for inline blending biodiesel and the initial testing of fuel blends for a Wartsila TM620, inline six cylinder, 4-stroke, 400 rpm, diesel engine generator set rated at 7.8MW. To facilitate this initial testing 6,000 gallons of Recycled Frying Oil Methyl Ester (RFO-ME) was delivered by ISO tank container from Oahu. The testing objective was to design a system that would facilitate emissions data collection for numerous blends, gain experience using the fuel, and to determine if nitrogen oxide emission levels would exceed our air permit. Engine performed well on all fuel blends, with a greater than expected increase in nitrogen oxide emissions, but within the limits of the air permit. Neat biodiesel (B100) resulted in an increased thermal efficiency when compared to #2 diesel. Inline blending is a safe effective method to control fuel blends.
Evaluation of a Spark Discharge Particulate Matter Sensor in a Turbocharged Diesel Engine
Authors: Gardiner David P. , Allan William D. , LaViolette Marc
Published: March 2009

This paper describes an experimental study of a Particulate Matter (PM) sensor that is intended for on-board control and diagnostic applications in diesel engines. The sensor measures the exhaust PM concentration based upon changes in the voltage waveform of a repetitive, low energy spark discharge. The sensor is electrically heated to prevent carbon fouling from diesel soot and to control its operating temperature. Earlier versions of the sensor were installed directly in the engine exhaust pipe like an Exhaust Gas Oxygen sensor. It was determined that the output of the PM sensor was sensitive to temperature as well as PM concentration, and variations in exhaust temperature made it difficult to maintain the sensor at a constant temperature. In the present study, the sensor was mounted in an electrically heated chamber and a portion of the engine exhaust was bypassed through the chamber. This made it possible to improve the stability of the sensor temperature, thereby reducing the sensitivity of the PM indication to changes in exhaust temperature as the engine load was varied. The PM sensor has been evaluated using a Caterpillar Model 3126 turbocharged 6-cylinder medium duty diesel engine. Small changes in load were used to create minor variations in exhaust PM levels. The PM levels were measured using an AVL 415S smoke meter. Experimental results are presented showing the correlation between the PM sensor signal and the reference PM measurements and the impact of speed and load variations on the correlation.
A Preliminary Study Towards an Innovative Diesel HCCI Combustion
Authors: Tamagna D. , Musu E. , Gentili R.
Published: March 2009

Homogeneous-charge, compression-ignition (HCCI) combustion is triggered by spontaneous ignition in diluted homogeneous mixtures and has a gradual trend thanks to suitable solutions. It is considered a very effective way to reduce engine pollutant emissions, however only experimental prototypes have been based on this concept, except for a few small two-stroke engines. HCCI combustion is feasible with fuels both for S.I. and for C.I. engines, but currently it does not cover the whole engine operating field, thus the engine must be built to operate also as a conventional engine. In order to obtain a gradual combustion and not a simultaneous reaction (as it would be in spontaneously ignited homogeneous mixture), lean mixture is used and appropriate solutions, as Exhaust Gas Recirculation (EGR), are necessary. However, the admission of exhaust gas into the cylinder goes to detriment of engine maximum mean effective pressure. This paper concerns a preliminary study of an innovative concept to control HCCI combustion in Diesel-fuelled engines, apart from exhaust gas presence, the function of which is limited to NOx emission control. The main purpose of the research is the obtaining of Diesel HCCI combustion also with high mean effective pressures rendering the combustion behaviour more controllable as well. The concept consists in forming a pre-compressed homogenous charge outside the cylinder and in gradually admitting it into the cylinder during the combustion process. In this way, combustion can be controlled by the flow rate transfer and high pressure gradients, typical of common HCCI combustion, can be limited as well. A first analysis has been done, considering a cylinder filled with a perfectly stirred mixture of air and diesel fuel through a transfer duct, only to test the validity of the concept, regardless of which effective solution will be adopted. Both Two and Four Stroke operations have been considered to realize the concept. Results in terms of pressure, heat release rate, temperature and emission production have pointed out the validity of the concept. Especially the Two Stroke solution produces more soot than the conventional Diesel, pointing out that the air-fuel mixing is probably not optimized. Regarding NOx emissions, both the proposed solutions give better results than the conventional Diesel engine.
The NOx and N2O Emission Characteristics of an HCCI Engine Operated With N-Heptane
Authors: Li Hailin , Neill W. Stuart , Guo Hongsheng , Chippior Wally
Published: March 2009

This paper presents the NOx and N2O emission characteristics of a Cooperative Fuel Research (CFR) engine modified to operate in Homogeneous Charge Compression Ignition (HCCI) combustion mode using an air-assist port fuel injector. The single-cylinder engine was fuelled with n-heptane for these experiments. The parameters examined include intake air temperature and pressure, air/fuel ratio, compression ratio, and exhaust gas recirculation (EGR) rate. The parameters were varied in order to change the combustion phasing from advanced (knocking) to retarded (incomplete combustion) conditions. NOx emissions were less than 5 ppm for a fairly wide range of combustion phases, except when knocking or incomplete combustion occurred, and were largely unaffected by the parameter varied when the combustion phase was within the acceptable range. It was also found that NOx emissions increased significantly when retarded and incomplete combustion was observed even though lower combustion temperatures were expected. The increased N2O and unburned hydrocarbon (THC) emissions usually observed with retarded combustion phasing, as well as the deteriorated combustion efficiency, may contribute to this unexpected increase in NOx emissions. It was also shown that N2O emissions were extremely low (less than 0.5 ppm) except when incomplete combustion was observed.
Turbocharger Component Matching System Development
Authors: Sengupta Jeet , Erickson Christopher , Keshavarz Ali , Chapman Kirby
Published: March 2009

This paper outlines the development of the Turbocharger Component Matching System (TuCMS) software package that can be used to inexpensively analyze turbocharger performance, and match turbocharger components to integrate and optimize turbocharger-engine performance. The software system is being developed with the intent to reduce the time taken to experimentally match a turbocharger with an engine, a task that is key to engine emission reductions. TuCMS uses one-dimensional thermo-fluid equations to analyze both the compressor and turbine side of a turbocharger. The program calculates the velocities, pressures, temperatures, pressure drops, and efficiencies for a specified set of turbocharger geometry and atmospheric conditions. Both the compressor and turbine side include established loss models found in the open literature. Work and rotational speed are the parameters used in the turbine and compressor analysis algorithms to integrate the turbocharger system. TuCMS utilizes a component-based architecture to simplify model enhancements. TuCMS can be used as a cost effective engineering tool for preliminary turbocharger testing during engine upgrades and modifications.
Description of Typical Flow Instabilities in the Natural Circulation System
Authors: Jiang Shengyao , Yang Xingtuan , Zhang Youjie
Published: March 2009

The experiments were performed on the test loop HRTL-5, which simulates geometry and system design of the 5-MW Nuclear Heating Reactor developed by the Institute of Nuclear Energy Technology, Tsinghua University. Because of the difference of the geometry design and operating conditions between the heating reactor and the boiling water reactor, the flow behavior presents great differences too, some of which haven’t been deeply studied so far. Results show that in heating reactor, sub-cooled boiling, condensation and flashing play an important role on the flow instabilities of the natural circulation system. Correspondingly, geysering instability, flashing instability, and flow excursion are the very typical instabilities occurring in the primary loop of HRTL-5, which are different from those in boiling water reactor conditions. The compressibility of the steam space on the top of the primary loop has also great influence on the instability of the natural circulation system.
Small LBE-Cooled Fast Reactor for Expanding Market
Authors: Sekimoto Hiroshi , Makino Shinichi , Nakamura Kunihiko , Kamishima Yoshio , Kawakita Takashi
Published: March 2009

A long-life safe simple small portable proliferation-resistant reactor is expected to solve many problems associating future energy and globally environmental problems. From discussions on mainly neutronics and safety points it has been shown that the heavy liquid metal cooled fast reactor is the best candidate to satisfy the above requirements. A lead-bismuth-eutectic (LBE) cooled fast reactor LSPR (LBE-Cooled Long-Life Safe Simple Small Portable Proliferation-Resistant Reactor) has been designed and continues to be improved. In the present paper a recent version of LSPR is presented. The total power of the present design is 150 MWt (53MWe). During whole reactor life of 12 years the excess reactivity required for burnup is very low, and negative coolant dilatation coefficient is confirmed. This characteristic together with some other characteristics makes unprotected loss of flow (ULOF) accident inherently safe. It can survive even simultaneous rod run-out transient over power (UTOP), ULOF and unprotected loss of heat sink (ULOHS) accident without the help of an operator or active device.
Steam Explosion Experiments Using ZrO2 and ZrO2/UO2 Mixture
Authors: Song Jinho , Park Ikkyu , Sin Yongseung , Kim Jonghwan , Hong Seongwan , Min Beongtae , Kim Heedong
Published: March 2009

Korea Atomic Energy Research Institute (KAERI) has been carrying an experimental research program on the steam explosion named “Test for Real cOrium Interaction with water (TROI)” since 1997. The objective of the program is to investigate whether the corium would lead to an energetic steam explosion and to measure the conversion ratio of the energetic steam explosion. In the first series of tests using several kg of ZrO2 where the melt/water interaction were made in the water pool at 30 ∼ 95 °C, either a quenching or a spontaneous steam explosions was observed. In the second series of tests using the mixture of UO2/ZrO2 performed in a similar manner as that of ZrO2, it also resulted in either a quenching or energetic steam explosion. The morphology of debris and pressure profile clearly indicate the differences in those two phenomena. The process parameters including the dynamic pressure, dynamic impulse, water and melt temperature, static pressure inside the containment chamber were measured.
Large-Break Loss-of-Coolant Accident Testing and Simulation for 200-MWe Simplified Boiling Water Reactor
Authors: Revankar S. T. , Xu Y. , Yoon H. J. , Ishii M.
Published: March 2009

The performance of the safety systems of a new design of the 200-MWe simplified boiling water reactor during a large-break, loss-of-coolant accident transient was investigated through code modeling and integral system testing. The accident considered was a break in the main steam line which is the major design basis accident. RELAP5/MOD3 best estimate reactor thermalhydraulic code was used and its applicability to the reactor safety system evaluation was examined. The integral tests were perfomed to assess the safety systems and the response of the emergency core cooling systems to accident conditions in a scaled facility called PUMA. The details of the safety system behavior are presented. The integral test simulations examined code applicability at the scaled facility level as well as prototype key safety system performance.
Evaluation of Debris Cooling Models in RPV Lower Head Based on Analysis for JAERI-ALPHA Test
Authors: Murase M. , Kohriyama T. , Yoshida Y. , Okano Y.
Published: March 2009

For severe accident assessment in a light water reactor (LWR), heat transfer models in a narrow annular gap between the overheated core debris and the reactor pressure vessel (RPV) are important for evaluating RPV integrity and emergency procedures. Some heat transfer models have been proposed as gap cooling CHF (critical heat flux) but local heat fluxes on the hot surface were not taken into account. Therefore, using the existing data, the authors developed heat transfer models on the average CHF restricted by CCFL (counter-current flow limitation) and local boiling heat fluxes, and showed that the average CHF depended on the steam-water flow pattern in the narrow gap and that the local heat fluxes were similar to the pool boiling curve. We evaluated the validity of heat transfer models by simple calculations for an ALPHA/IDC001 experiment performed by JAERI (Japan Atomic Energy Research Institute). Results showed heat fluxes on the crust surface were restricted mainly by its thermal resistance after the crust formation, emissivity on its surface did not have much effect on the heat fluxes, and the calculated vessel temperature during the heat-up process agreed well with the measurements. However, the vessel cooling rate was underestimated mainly due to underestimation of the gap size. The heat fluxes on the vessel inner surface were much higher than the pool film boiling therefore local boiling heat transfer should be studied to improve the heat transfer models.
Results of the Quench-07 Experiment
Authors: Miassoedov Alexei , Homann Christoph , Sepold Leo , Steinbru¨ck Martin
Published: March 2009

QUENCH is a series of experiments being performed at the Forschungszentrum Karlsruhe, to investigate quenching with water and cooling with steam of oxidized and partially degraded fuel rod bundle. Test QUENCH-07 was performed to address the effects of chemical behavior and degradation of B4C absorber rods, especially the oxidation of B4C, its interaction with stainless steel, formation and composition of gaseous reaction products and the impact of absorber rod degradation on surrounding rods. An unexpected feature of the experiment was the strong oxidation during the cooldown phase accompanied by an increased release of all gaseous species. Temperature escalation and hydrogen release during cooldown were observed for the first time in any steam cooled QUENCH experiment. Since not only the absorber rod was a novel feature but also the steam flow rate during cooldown was smaller in comparison with previous tests, it is not yet clear whether this escalation can be attributed to the effect of B4C.
Progress in Development of a Low Energy Reaction Cell for Distributed Power Applications
Authors: Miley G. H. , Castano C. , Lipson A. , Kim S. O. , Luo N.
Published: March 2009

Power units using Low Energy Nuclear Reactions (LENRs) potentially offer a radical new approach to power units that could provide distributed power units in the 1–50 kW range. As described in prior ICONE papers [9, 23] these cells employ thin metallic film cathodes (order of 500 Å, using variously Ni, Pd and Ti) with electrolytes such as 0.5–1 molar lithium sulfates in light water. Power densities exceeding 10 W/cc in the films have been achieved. An ultimate goal is to incorporate this thin-film technology into a “tightly packed” cell design where the film material occupies ∼ 20% of the total volume. If this is achieved, power densities of ∼20 W/cm3 appear feasible, opening the way to a number of potential applications involving distributed power. Recent studies reported here have concentrated on new electrode designs intended to maximize the proton loading in the films while maintaining the required proton and electron current densities.
Vibration Characteristics of a Vertical Round Tube According to Heat Transfer Regimes
Authors: Lee Yong Ho , Chang Soon Heung , Baek Won-Pil
Published: March 2009

This paper presents the results of an experimental work on the effects of boiling heat transfer regimes on the flow-induced vibration (FIV). The experiment has been performed using an electrically heated vertical round tube through which water flows at atmospheric pressure. Vibration characteristics of the heated tube are changed significantly by heat transfer regimes and flow patterns. For single-phase liquid convection, the rod vibrations are negligible. However, on the beginning of subcooled nucleate boiling at tube exit, vibration level becomes very large. As bubble departure occurs at the nucleation site of heated surface, the vibration decreases to saturated boiling region where thermal equilibrium quality becomes 0.0 at tube exit. In saturated boiling region, vibration amplitude increases with exit quality up to a certain maximum value due to the reinforced turbulence then decreases. At liquid film dryout condition, vibration could be regarded as negligible, however, these results cannot be extended to DNB-type CHF mechanism. Frequency analysis results of vibration signals suggested that excitation sources be different with heat transfer regimes. This study would contribute to improve the understanding of the relationship between boiling heat transfer and FIV.
A CFD Model for High Pressure Liquid Poison Injection for CANDU-6 Shutdown System No. 2
Authors: Rhee Bo Wook , Jeong Chang Joon , Yun Hye Jeong , Jang Dong Soon
Published: March 2009

In CANDU reactor one of the two reactor shutdown systems is the liquid poison injection system which injects the highly pressurized liquid neutron poison into the moderator tank via small holes on the nozzle pipes. To ensure the safe shutdown of a reactor it is necessary for the poison curtains generated by jets provide quick, and enough negative reactivity to the reactor during the early stage of the accident. In order to produce the neutron cross section necessary to perform this work, the poison concentration distribution during the transient is necessary. In this study, a set of models for analyzing the transient poison concentration induced by this high pressure poison injection jet activated upon the reactor trip in a CANDU-6 reactor moderator tank has been developed and used to generate the poison concentration distribution of the poison curtains induced by the high pressure jets injected into the vacant region between the pressure tube banks. The poison injection rate through the jet holes drilled on the nozzle pipes is obtained by a 1-D transient hydrodynamic code called, ALITRIG, and this injection rate is used to provide the inlet boundary condition to a 3-D CFD model of the moderator tank based on CFX4.3, a CFD code, to simulate the formation of the poison jet curtain inside the moderator tank. For validation, an attempt was made to validate this model against a poison injection experiment performed at BARC. As conclusion this set of models is judged to be appropriate.
Assessment of Ultimate Load Capacity for Pre-Stressed Concrete Containment Vessel Model of PWR Design With BARC Code ULCA
Authors: Basha S. M. , Singh R. K. , Patnaik R. , Ramanujam S. , Kushwaha H. S. , Raj V. Venkat
Published: March 2009

Ultimate load capacity assessment of nuclear containments has been a thrust research area for Indian Pressurised Heavy Water Reactor (PHWR) power programme. For containment safety assessment of Indian PHWRs a finite element code ULCA was developed at BARC, Trombay. This code has been extensively benchmarked with experimental results. The present paper highlights the analysis results for Prestressed Concrete Containment Vessel (PCCV) tested at Sandia National Labs, USA in a Round Robin analysis activity co-sponsored by Nuclear Power Engineering Corporation (NUPEC), Japan and the U.S Nuclear Regulatory Commission (NRC). Three levels of failure pressure predictions namely the upper bound, the most probable and the lower bound (all with 90% confidence) were made as per the requirements of the round robin analysis activity. The most likely failure pressure is predicted to be in the range of 2.95 Pd to 3.15 Pd (Pd = design pressure of 0.39 MPa for the PCCV model) depending on the type of liners used in the construction of the PCCV model. The lower bound value of the ultimate pressure of 2.80 Pd and the upper bound of the ultimate pressure of 3.45 Pd are also predicted from the analysis. These limiting values depend on the assumptions of the analysis for simulating the concrete-tendon interaction and the strain hardening characteristics of the steel members. The experimental test has been recently concluded at Sandia Laboratory and the peak pressure reached during the test is 3.3 Pd that is enveloped by our upper bound prediction of 3.45 Pd and is close to the predicted most likely pressure of 3.15 Pd.
Sensitivity Degradation Characteristics of Incore Neutron Detector for Heavy Water Reactor, Fugen NPP
Authors: Okawa Tsuyoshi , Yomori Naoyuki
Published: March 2009

Fugen nuclear power plant is a 165MWe, heavy water-moderated, boiling light water-cooled, pressure tube-type reactor developed by JNC, which is the world’s first thermal neutron power reactor to utilize mainly Uranium and Plutonium mixed oxide (MOX) fuel. Fugen has been loaded a total of 726 MOX fuel assemblies since the initial core in 1978. Each incore neutron detector assembly of Fugen composed of four Local Power Monitors (LPM) is located at sixteen positions in the area of heavy water moderator in the core and monitors its power distribution during operation. The thermal neutron flux of Fugen is relatively higher than that of Boiling Water Reactor (BWR), therefore LPM, which is comprised of a fission chamber, degrades more quickly than that of BWR. An Improved Long-life LPM (LLPM) pasted inner surface wall of the chamber with 234U/235U at a ratio of 4 to 1 had been developed through the irradiation test at Japan Material Test Reactor (JMTR). The 234U is converted to 235U with absorption of neutron, and compensates the consumption of 235U. LPM has been loaded to the initial core of Fugen since 1978. JNC had evaluated its sensitivity degradation characteristics through the accumulated irradiation data and the parametric survey for 234σa and 235σa. Based on the experience of evaluation for sensitivity degradation, JNC has applied shuffling operation of LPM assemblies during an annual inspection outage to reduce the operating cost. This operation realizes the reduction of replacing number of LPM assemblies and volume of radioactive waste. This paper describes the sensitivity degradation characteristics of incore neutron detector and the degradation evaluation methods established in Fugen.
Experimental Study on Fluid Mixing for Evaluation of Thermal Striping in T-Pipe Junction
Authors: Igarashi Minoru , Tanaka Masaaki , Kawashima Shigeyo , Kamide Hideki
Published: March 2009

A water experiment is performed to investigate thermal striping phenomena in a T-pipe junction which is a typical geometry of fluid mixing. The flow velocity ratio and temperature difference were experimental parameters. The jet form was classified into four patterns; (1) impinging jet, (2) deflecting jet, (3) re-attachment jet and (4) wall jet according to the inflow condition. The parameter experiments showed that the jet form could be predicted by a momentum ratio between the two pipes. The thermochromic liquid crystal sheet showed that a cold spot was formed at the wall surface in the main pipe in the cases of the impinging jet and the wall jet. From the temperature measurement in the fluid, temperature fluctuation intensity was high along the edge of the jet exiting from branch piping. A database of temperature fluctuation and frequency characteristics was established for an evaluation rule of thermal striping in a T-pipe junction.
Increase of Steam Moisture in the BWR-Facility KKP 1
Authors: Noack Volker
Published: March 2009

Main steam moisture in a BWR facility is determined by steam quality at core outlet and efficiency of steam separators and steam dryers. Transport of water with steam is accompanied by transport of radionuclides out of RPV resulting in enhanced radiation level in the main steam system. A remarkable increase of main steam moisture started at KKP 1 in 1997. In the following years increase of steam outlet moisture started at lower and lower core mass flow rates. Dose rate in main steam system increased simultaneously. Core mass flow rate and thus thermal power had to be reduced during stretch out operation to keep the main steam moisture below the specified boundary of 0.2%. This boundary also guarantees, that radiological exposure remains far below approved values. The increase of main steam moisture corresponds with the application of low leakage core loading. Low leakage core loading results in enhanced steam generation in the center and in reduced steam generation in the outer zones of the core. It can be shown, that the uneven steam generation in the core became stronger over the years. Therefore, steam quality at inlet of the outer steam separators was getting lower. This resulted in higher carry over of water in this steam separators and steam dryers, thus explaining the increasing main steam moisture. KKP 1 started in 2000 with spectral shift operation. As one should expect, this resulted in reduced steam moisture. It remains the question of steam moisture in case of stretch out operation. Countermeasures are briefly discussed.
Development of a Containment Code KUPOL-M for a Substantiation of the VVER’s Accident Localization System Functions
Authors: Efanov A. D. , Loukianov A. A. , Shangin N. N. , Yuriev Yu. S. , Zaitsev A. A. , Soloviev S. L. , Zaitchik L. I.
Published: March 2009

Computer code KUPOL-M is made for analysis of thermodynamic parameters of medium within full pressure containment for NPPs with VVER under LOCA conditions. The analysis takes into account the effects of non-stationary heat-mass transfer of gas-drop mixture in containment compamnents with natural convection, volume and surface steam condensation in the presence of noncondensables, heat-mass exchange of compartment atmosphere with water in sumps. The model for hydrogen deflagration is capable of evaluating gas temperature and pressure in specified containment compamnents. The operation of the main safety systems is simulated in KUPOL-M code including spray system, hydrogen catalytic recombiners, emergency core cooling pumps, valves and fan system. Vast program of the code testing and verification is performed at each stage of development. Verification matrix of KUPOL-M code comprises separate effects experiments (e.g. volumetric or surface steam condensation) as well as integral tests, reproducing at some extent conditions of design basis and severe accidents of LOCA type. Main results of the code verification are presented.
Design and Process Improvements on the Waste Treatment of Angra I and Angra II Power Plants in Brazil
Authors: de Tello Cle´dola Ca´ssia Oliveira , Barroso Antoˆnio Carlos de Oliveira
Published: March 2009

Evolving differences, in Brazilian regulatory framework from the time Angra I was designed, in the beginning of the sixties, to the time of license evaluation, in the late seventies, resulted in the unacceptability of the original waste solidification system. The end products could not reach the necessary characteristics required for transport and storage and a redesign was necessary to improve the cementation process. In the case of Angra II, which uses a bituminisation system to solidify its low and intermediate level liquid wastes, some minor adjustments had to be done in the process and a new bitumen specification had to be developed to select a Brazilian material so that the system could perform adequately and meet the national requirements for safe transportation and storage.
Increased Availability From Improved Condenser Design
Authors: Harpster Joseph W.
Published: March 2009

Performance parameters and flow characteristics on the shell side of surface condensers are becoming better understood. Contributing to this knowledge base is the recent ability to measure the physical properties as well as the quantity of gases being removed from the condenser by air removal equipment. Reviewed here are the commonality of these data from many operating condensers obtained over the past six years and other known condenser measurements, theory and laboratory experiments. These are combined to formulate global theoretical description of condenser dynamics describing the mechanism responsible for aeration and de-aeration, excess back pressure buildup due to air ingress or generation of other noncondensable gases, and the dissolubility of corrosive gases in condensate. The theoretical description supports a dynamic model useful for deciding condenser configuration design and design improvements. Features of design found in many operating condensers that promote aeration and resulting corrosion are presented. The benefits of the model and engineering design modifications to plant life cycle management, improved condenser performance, outage reduction and reliability improvements, lost load recovery and fuel savings are discussed.
MELCOR 1.8.5 Simulation of TMI-2 Phase 2 With an Enhanced 2-Dimensional In-Vessel Natural Circulation Model
Authors: Gauntt Randall O. , Ross Kyle , Wagner Kenneth
Published: March 2009

Phase 2 of the TMI-2 accident (core uncovery and melting) is revisited with the latest release of MELCOR (i.e., Version 1.8.5). An enhanced multi-ring multi-level hydro nodalization of the reactor core and upper plenum was developed to permit calculation of natural convection heat transfer between the core and upper internals. Uncertainties in boundary and initial conditions are investigated with particular attention given to the distribution of liquid in the RCS at the beginning of Phase 2 and to the histories of pressure and level in the steam generators. Special attention given to modeling the boiler sides of the once-through steam generators is presented. The modeling is designed to capture the rapid condensation of RCS vapor that would result from spraying cold auxiliary feedwater directly onto the upper portion of a voided steam generator tube bundle. Presentation of key Phase-2 accident signatures including fuel temperatures and hydrogen generation are presented. Comparisons are made between MELCOR calculations, TMI-2 data, and SCDAP/RELAP simulations. A largely improved MELCOR simulation of TMI-2 Phase 2 is obtained.