bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of Condensation Induced Water Hammer
Authors: Prica Sanja , Stevanovic Vladimir , Maslovaric Blazenka
Published: November 2008

A numerical model for the simulation and analyses of condensation induced water hammer is presented and applied to the prediction of intensive pressure waves propagation in a two-phase pipe system. The modelling approach is based on the one-dimensional homogeneous two-phase flow model, tracking of the water column–steam bubble interface and modelling of the direct steam condensation on the subcooled liquid. The mass, momentum and enthalpy conservation equations are solved with the method of characteristics. The explicit time integration is performed along the three characteristic paths, where two of them are determined with the pressure waves propagation and third by the fluid particle flow. Fluid particle and water-steam interface tracking is achieved through the third-order accurate solving of the energy equation in space, where the thermodynamic quality determines the presence of water, two-phase mixture or steam. The heat conduction term is included into the enthalpy equation with the appropriate effective heat conduction coefficient in the two-phase region. The model is applied to the simulation and analyses of condensation induced water hammer in laboratory test case.
Preliminary Evaluation of the Fixed Bed Nuclear Reactor Concept Using IAEA-INPRO Methodology
Authors: Sefidvash Farhang
Published: November 2008

The Atomic Energy Agency (IAEA) through its INPRO Project has developed a methodology to evaluate the innovative nuclear reactors. The main objectives of INPRO are to help to ensure that nuclear energy is available in the 21st century in a sustainable manner; and bring together both technology holders and technology users to achieve desired innovations in nuclear reactors and nuclear fuel cycles which are to be acceptable to the public because they are economic, safe, proliferation resistant, sustainable, and having reduced environmental impact. Here is a preliminary application of this methodology (IAEA-TECDOC-1362) to evaluate the Fixed Bed Nuclear Reactor Concept (FBNR). Some of the characteristics of the proposed reactor are: The FBNR is based on pressurized light water reactor technology. It is a small, modular, and integrated primary circuit reactor. The fuel elements of FBNR are 8 mm diameter spherical uranium dioxide pellets cladded by zircaloy or made of compacted TRISO type fuel particles. The reactor core is suspended by the flow of water coolant. The stop in flow causes the fuel elements leave the reactor core by the force of gravity and fall into a passively cooled fuel chamber or even leave the reactor completely and become deposited in the spent fuel pool. It is an inherently safe and passively cooled reactor concept. FBNR in its advanced versions can use supercritical steam or helium gas as coolant, and utilize MOX or thorium fuel.
A Review of Root Causes of SCC Phenomena in BWR/RBMK: An Overview of Radiation-Induced Long Cell Action Relevant to SCC
Authors: Saji Genn
Published: November 2008

In a review of recent occurrences of Stress Corrosion Cracking (SCC) in Japanese Boiling Water Reactors (BWRs) and Russian High Power Channel-type Reactors (RBMKs), the author proposes a hypothetical mechanism which states; ‘radiation-induced ‘long cell action’ causing electrolytic corrosion.’ This article provides the currently available technical bases for the proposed mechanism which was introduced in a companion paper also presented at this conference [1]. There is some experimental evidence indicating that long cell action may not be negligible in nuclear reactor environments, when induced by the radiolysis of water. There are also some surprising similarities between SCC in the reactor systems and the basic mechanism of underground corrosion by long cell action. In this mechanism, the ‘long cell action’ is induced by a difference in availability of oxygen inside the soil. Conduction of electrons through an electric conductor over a long distance plays a significant role as they are released by dissolution of metallic ions and sucked up from the metal surface.
Simulations of the Pressurizer Safety Valve Stuck Open Accident for the Development of the Accident Sequences in the Low Power/Shutdown PSA
Authors: Lim Ho-Gon , Park Jin-Hee , Jang Seung-Chul , Kim Tae-Woon
Published: November 2008

We have simulated the pressurizer safety valve (PSV) stuck open accident in a Korea Standard Nuclear power Plant (KSNP). The purpose of the simulation is 1) to investigate the mitigation function available for the important accident sequence having considerable core damage frequencies and 2) to support the determination of the accident sequences with relevant success criteria for the Low Power Shutdown (LP&S) Probabilistic Safety Assessment (PSA). The analysis showed that the PSV stuck open accident in a KSNP has both the characteristics of a small and medium LOCA in the sense that the primary system pressure decreases slowly but the break flow is sufficient enough to uncover the core in the early stages of the accident. we found that, in the accident sequence of a high pressure safety injection (HPSI) failure, core damage could occur earlier before reaching the actuation set-pressure of the safety injection tank (SIT) provided that no operator action is considered. We also performed the simulation of a rapid cool-down by a steam generator for this accident sequence to investigate the feasibility of the SIT injection before core damage occurs. From these simulations, if the operators start the rapid cool-down operation within 15 minutes, it was shown that SIT could be injected and core damage could be prevented if the subsequent Low Pressure Safety Injection (LPSI) and Shutdown Cooling System (SCS) is successfully operated.
Validation of the Fast-Running In-Vessel Model ASTRID for Predicting the Radioactive Releases to the Containment
Authors: Jaakko Miettinen , Schmuck Philipp
Published: November 2008

The ASTRID (Assessment of Source Term for Emergency Response based on Installation Data) process model is used for the faster than real-time prediction of the radioactivity released into the containment and further into the environment in case of an emergency situation in a light water reactor. Combined together with the containment module COCOSYS the model can predict the entire radioactivity release chain from the primary system to the containment and further into the environment. In the paper the ASTRID thermohydraulic module PROCESS is presented shortly. The thermohydraulic part is a fast running solution for the drift-flux based thermohydraulics. In high temperatures the core degradation leading to the melt pool formation in the reactor barrel and reactor vessel lower head is calculated in the in-vessel module RELOMEL. Finally after the reactor vessel wall has been eroded due to the molten corium in the lower plenum, the massive radioactivity release occurs into the containment. But even before this scenario the radioactivity may be transported from the superheated core to the containment by the coolant. The reference plants for the development have been the Westinghouse type 4-loop PWR, the French type 3-loop PWR, The German type 4-loop Konvoi PWR, the Loviisa VVER type PWR, and the Olkiluoto type internal pump BWR. The reference code for the DBA thermal hydraulics has been the SMABRE code. In the developmental assessment the capability of the rough nodalization of ASTRID has been tested against the SMABRE nodalization describing the plants with 50–500 nodes. For the developmental assessment of the in-vessel severe accident the sample cases are calculated with MELCOR. The more thorough validation is based on the internationally known system codes, RELAP5, MELCOR, CATHARE and ATHLET. In the validation the most problematic area is the radioactivity transport into the containment. This part of the validation is done with the integrated code system.
Assessment of Irradiation Conditions in WWER-440 (213) RPV Surveillance Location
Authors: Ballesteros A. , Bros J. , Debarberis L. , Sevini F. , Erak D. , Gezashchenko S. , Kryukov A. , Shtrombakh Y. , Goloschapov S. , Ionov A. , Pytkin Y. , Anikeev Y. , Banyuk G. , Plusch A. , Gillemot F. , Petrosyan V.
Published: November 2008

The key component of WWER is the Reactor Pressure Vessel (RPV). The evaluation and prognosis of RPV material embrittlement and the allowable period of its safe operation are performed on the basis of impact test results of irradiated surveillance specimens (SS). The main problem is that the SS irradiation conditions (temperature of SS, neutron flux and neutron spectrum) have not been determined yet with the necessary accuracy. These conditions could differ from the actual RPV condition. In particular, the key issue is the possible difference between the irradiation temperature of the SS and the actual RPV temperature. It is recognized that the direct measurement of temperature by thermocouples during reactor operation is the only way for receiving reliable information. In addition, the neutron field’s parameters for surveillance specimens have not been determined yet with the necessary accuracy. The use of state of the art dosimeters can provide high accuracy in the determination of the neutron exposure level. The COBRA project (http://ie.jrc.cec.eu.int/ames/), which started in August 2000 and had a duration of three years, was designed to solve the above-mentioned problems. Surveillance capsules were manufactured which contain state of art dosimeters and temperature monitors (melting alloys). In addition, thermocouples were installed throughout the instrumentation channels of the vessel head to measure directly the irradiation temperature in the surveillance position during the reactor operation. The selected reactor was the Unit 3 of Kola NPP situated in the arctic area of Russia. Irradiation of the capsules and online temperature measurements were performed during one fuel cycle. On the base of statistical processing of thermocouples readings the temperature of irradiated surveillance specimens in WWER-440/213 reactor can be accepted as 269.5±4°C. The results obtained show that there is not need in temperature correction when data of surveillance specimens studies are used for assessment of WWER-440/213 reactor pressure vessels. Maximum neutron flux evaluated using detectors, which were placed in the Charpy specimen simulators, equals ∼2.7·1012 cm−2s−1 with E>0.5 MeV. It is established that depending on the orientation of the capsules with respect to the core, the detectors of the standard surveillance capsules can give both overestimated and underestimated neutron flux values, as compared to the actual flux received by the surveillance specimens. The overestimation or underestimation can reach 10%.
Bolted Joint Integrity Management: Implementing Industry Best Practice
Authors: Metzger Dave
Published: November 2008

Holistic asset management aimed at all aspects of improved safety and business performance has identified poor bolt tightening as a major cause of leaks, thereby raising the need for understanding the concept of joint integrity and in particular the requirement to apply more control throughout this often overlooked process. The UK government’s Health and Safety Executive has reported on industry poor practice in offshore oil and gas applications, and working with the United Kingdom Offshore Operators Association (UKOOA) has produced guidelines and recommendations for the reduction of hydrocarbon leaks from bolted joints. This recommended safe practice, the lessons learnt and the guidelines made are equally applicable to the power generation industry and in particular the nuclear one. The goals of leak free assembly, failure reduction and the elimination of wasted time and effort are achieved through the use of a risk based approach and the implementation of industry best practice. Building on experience learnt from the petrochemical industry: - this paper will provide guidelines relevant to the nuclear power generation industry for leak avoidance using risk assessment methods and competency management to establish the principles of a Joint Integrity Management System and highlight best industrial practice.
Evaluation of Seismic Integrity for an Integral Reactor Assembly
Authors: Wang Soon Myeon , Kim J. S. , Jin T. E. , Jhung M. J. , Choi Y. H. , Jo J. C.
Published: November 2008

The structural integrity of integral reactor assembly of 65Mwt thermal capacity is assessed by using the commercial finite element package ANSYS in order to evaluate the seismic safety margin. First of all, the modal analyses are performed using the various analysis models with/without the fluid coupling effect in order to validate a super element model and to evaluate the coupling effect on natural frequency. Based on the modal analysis results, the seismic analyses are performed using the ground response spectrum defined in Reg. Guide 1.60. Finally, time-history analyses are performed using the modal analysis results, the super element model and an inertia load approach. As a result, the reliable and efficient seismic analysis model for an integral reactor assembly is developed and it is found that an integral reactor assembly has the sufficient seismic safety margin.
Development of a Nuclear Reactor Two-Phase Natural Circulation CFD Model
Authors: Botelho D. A. , De Sampaio P. A. B. , Moreira M. L. , Faccini J. L. H.
Published: November 2008

A circuit of natural convection similar to the passive reactor heat removal systems of the AP600 reactor and of the APEX experiment was constructed in the Nuclear Engineering Institute located in Rio de Janeiro. In an attempt to improve usual numeric methods, it was developed a new Computational Fluid Dynamics (CFD) scheme to solve one-dimensional (1D) two-phase natural circulation transport equations. To compare the new scheme with other numeric methods, it was used the results of the two-phase experiment conducted at the University of Sa˜o Paulo (USP). It was compared the frequency and the amplitude of the temperature oscillations at several positions of the spatial domain during a two-phase heating transient. The results of the new method show a better agreement with the experiment than that obtained from the RELAP and the TRAC series of computer programs.
Measurement and Analysis of Bubble Behavior in Subcooled Nucleate Boiling Flow Field With High Fidelity Imaging System
Authors: Wu Wen , Jones Barclay G. , Newell Ty A.
Published: November 2008

To date, more than twenty PWRs have been affected by axial offset anomaly (AOA) or crud-induced power shift (CIPS), an unexpected deviation in the core axial power distribution from the predicted curve during operation. AOA is a current major consideration for reactors operating at increased power levels and is becoming immediate threat to nuclear power’s competitiveness in the market [1]. Despite much effort focusing on this topic, a comprehensive understanding is far from being developed. However, previous research indicates that a close connection exists between subcooled nucleate boiling occurring in core region and the formation of crud, which directly results in AOA phenomena. It is well established that deposition is greater, and sometimes much greater, on heated than on unheated surfaces. [2] A number of researchers have suggested that boiling promotes deposition, and several observed increased deposition in the subcooled boiling region [2]. Limited detailed information is available on the interaction between heat and mass transfer in subcooled nucleate boiling (SNB) flow. It is speculated that direct prediction of the AOA from SNB is difficult. Moreover, bubbles formed in SNB region play an important role in helping the formation of crud. Therefore, we are encouraged to get a better understanding of SNB phenomena and the behavior of the bubbles in SNB. This research examines bubble behavior under SNB condition from the dynamic point of view, using a high fidelity digital imaging apparatus. Freon R-134a is chosen as a simulant fluid due to its merit of having smaller surface tension and lower boiling temperature. The apparatus is operated at “reduced” pressure. Series of images at frame rates up to 4000 frames/s were obtained, showing different characteristics of bubble behavior with varying experimental parameters e.g. flow velocity, fluid subcooled level, etc. Analyses that combine the experimental results with analytical result on flow field in velocity boundary layer are considered. A tentative suggestion is that a rolling movement of a bubble accompanies its sliding along the heating surface in the flow channel. Numerical computations using FLUENT v5.5 are performed to support this conclusion.
Nanolithography Using High Transmission Nanoscale Ridge Apertures
Authors: Uppuluri Sreemanth , Jin Eric X. , Xu Xianfan
Published: November 2008

In this paper, we describe using high transmission nanoscale apertures of C and H shapes for nanolithography applications. We demonstrate that these ridge apertures provide a highly localized and intense light spot that can be used in lithography experiments.
Reconstituting Membrane Proteins Into Artificial Membranes and Detection of Their Activities
Authors: Lee Hyeseung , Ho Dean , Chu Benjamin , Kuo Karen , Montemagno Carlo
Published: November 2008

We have successfully purified BR from purple membrane of Halobacterium Salinarium and Cox from the genetically engineered plasmid inserted in Rhodobacter Sphaeroides. The activities of the purified enzymes have shown in lipid vesicles as well as in polymer vesicles and planar membranes. Phosphatidylcholine derived lipid vesicles created the most nature like environment for the enzymes. Triblock copolymer membrane was the alternative choice for membrane protein reconstitution since polymers are more durable, ideal for industrial applications and support enzyme activities better. We also demonstrated the backward function of Cox in vitro by changing proton concentration in the surrounding medium. Langmuir-Blodgett method was used to reconstitute the enzymes into the planar lipid or polymer membranes. The enzyme activities of the enzymes in planar membrane system were tested by impedance spectroscopy.
Fountain-Pen-Based Laser Microstructuring With Gold Nanoinks
Authors: Choi Tae Y. , Poulikakos Dimos , Grigoropoulos Costas P.
Published: November 2008

Employing the fountain pen principle, a micropipette is used to write an Au nanoparticle ink on glass substrates. A continuous-wave laser (488–515 nm) is subsequently used as a controlled, localized energy source to evaporate the carrier liquid (toluene) in the ink and sinter the nanoparticles together thus fabricating continuous gold stripes 5 micrometers in width and a few hundred nanometers in height. The scanning speed, the laser intensity, and the degree of defocusing are identified as important parameters to the successful manufacturing of the gold microstructures. The electrical resistivity of the stripes, within the parametric domain of the present work, is measured to be the order of 10−6 ohm-m.
An Improved Analytical Approach to Steam Turbine Heat Transfer
Authors: Brilliant Howard M. , Tolpadi Anil K.
Published: November 2008

Improvements to the design of advanced steam turbines require an improved understanding of the heat transfer within the various components of the unit. Physics-based ANSYS models for typical high pressure and intermediate pressure units have been developed. The boundary conditions were derived from full-load, steady state flow analyses, steam turbine performance code outputs and computational fluid dynamics (CFD) analyses to develop normalized (non-dimensional) local flow conditions, with the normalizing parameters based on key cycle parameters. These normalized local flow conditions and cycle parameters were then used to define local transient boundary temperatures and heat transfer coefficients for input to the thermal ANSYS model. Transient analyses of components were performed. The results were compared with temperature measurements taken during the operating cycle of an operational steam turbine to validate and improve the methodology and were applied to structural models of the components to predict their thermal growth and the net impact on the clearance between the rotor and diaphragms and other secondary flow paths in the steam turbine, including seals.
Rotating Effects on Heat Transfer Rate in a Cooling Air Passage of a Gas Turbine Blade
Authors: Sierra Fernando Z. , Garci´a Juan C. , Kubiak Janusz , Urquiza Gustavo
Published: November 2008

In this paper numerical results on the effects of rotation on heat transfer rates in a cooling air passage that belongs to a gas turbine blade are presented. A 180° turn about has been considered into the computations. Rotation rates of 1145, 2800 and 3600 rpm were considered into the analysis. Comparisons for a Re = 53 000 with literature published results showed a good agreement. The simulation has been based on the finite volume approach of a 3-D flow using a second moment closure model for modeling the turbulence in the air passage. The results indicate that the rotation rate produces important changes in the heat transfer rate. In this work heat transfer has been characterized through the Nusselt number, along the air flowing path. A rotation rate of 3600 rpm produces an increment of the heat transfer rate by 14% along the inlet edge of the blade compared with the condition of no rotation. However, a decrease of 16.7% is observed in the outlet edge under the same conditions, compared against the non rotating condition. The situation is drastic in the tip region of the blade where more than 18.5% higher heating rate is observed for the same rotating speed. These results correspond to the outer internal wall of the blade passage, while the situation for the inner wall are in general less severe. The velocity field shows the formation of several secondary cells of flow which may represent stagnation regions for both pressure and heat transfer. These secondary cells are observed mainly in the region of the turn of 180°. The dynamics of these cells are important for the performance and design of the cooling system in gas turbines.
Effect of Equivalence Ratio and Burner Geometry on the Characteristics of Laminar Premixed Flames at Moderate Coflow
Authors: Hariharan P. , Gollahalli S. R.
Published: November 2008

The importance of studying laminar premixed flames lies in applications such as gas ranges and ovens, heating appliances and Bunsen burners. With the current demand for large amounts of economical, clean power, there is a need for research in increasing the combustion efficiency. Laminar premixed Propane/Hydrogen/Air flames with 3 m/s coflow and without coflow, with a variation of jet equivalence ratio (JEQ) from 0.5 to 4 for 20 m/s jet velocity, have been studied experimentally to determine the interactions of burner geometry of premixed flames and coflow. Two different burner geometries (circular burner, and 3:1 aspect ratio (AR) burners) were used in the experiments. The stability tests indicated that for 20 m/s jet velocity both at quiescent and coflow conditions the circular burner was more stable than the 3:1AR elliptical burner. Flame height studies indicated that circular burner flames were taller than the 3:1AR elliptical burner flames. However, there was a reduction in flame height when coflow air velocity of 3 m/s was introduced. Temperature profile indicated a higher peak temperature for circular burners followed by elliptical burner, both at quiescent and coflow conditions. The introduction of moderate coflow showed a decrease in NO production rate. In order to explain the structure of the flame in detail and various mechanisms that lead to the explanation of global flame characteristics, inflame concentration measurements were taken in near burner (25% of flame height), mid burner (50% of flame height) and far burner (75% of flame height) regions of the flame.
Get Rid of Those Pad Welds and Other Temporary Repairs
Authors: Bartholomew Robert D. , Labuda Ewa M. , Roberts Gary H.
Published: November 2008

Pad welding and window welds are techniques that are commonly used for emergency repairs of damaged tubes during unscheduled shutdowns. During subsequent scheduled outages, tube sections with these temporary repairs should be cut out of the boiler and replaced with new tubes. Some plants have left these areas in the furnace for long periods of time and subsequent damage and secondary failures have occurred. This paper provides evidence to support removal of pad welds and other types of temporary repairs from a boiler during routine outages.
The Need for In-Situ Pipe Support Testing
Authors: May Gerry
Published: November 2008

Pipe support functionality is critical to the long term life of piping system. Spring supports degrade with time due to flexing in the spring and wear in constant support bearings. It is not unusual to measure constant support hangers with resistance 25% to 50% different than the design load. This leads to excessive sustained pipe stress, pipe sag (or uplift), and in high temperature systems, accelerated creep damage. Supports may also not move properly from shut down to full operation, which can create excessive fatigue stress, failed hanger components, and other piping system damage. In-situ hanger testing has been found to be a reliable and cost effective method to determine the functionality of pipe supports. Results are used as input to set revised recommended loads, and to determine if any hangers need to be replaced. This paper provides examples of the types of problems that are often found in the field, the method to test, and typical resolutions to maximize the pipe life and minimize the risk of failure.
Slag and Deposit Monitoring at TVA Cumberland
Authors: Breeding Charlie , Johnson Rabon , Zimmerman Ben
Published: November 2008

Tennessee Valley Authority’s Cumberland Fossil Plant, EPRI and Clyde Bergemann Inc. are collaborating on a test and demonstrate project a novel technology for measuring upper furnace slag deposition. The project team has installed a system of 18 strain gages on the superheater pendant section of the 1300 Mw unit 1 boiler to provide information on the slag and ash deposit accumulation on the pendants. The system is designed identify “clinkers” that form in the pendant section and further to enable further assessment for determining the ability of intelligent soot blowing to remove the slag. This paper will discuss the project objectives, system configuration, expected results and benefits and plans for further deployment of the technology.
Introducing the 1S.W501G Single-Shaft Combined-Cycle Reference Power Plant
Authors: Engelbert Christian , Fadok Joseph J. , Fuller Robert A. , Lueneburg Bernd
Published: November 2008

Driven by the requirements of the US electric power market, the suppliers of power plants are challenged to reconcile both plant efficiency and operating flexibility. It is also anticipated that the future market will require more power plants with increased power density by means of a single gas turbine based combined-cycle plant. Paramount for plant efficiency is a highly efficient gas turbine and a state-of-the-art bottoming cycle, which are well harmonized. Also, operating and dispatch flexibility requires a bottoming cycle that has fast start, shutdown and cycling capabilities to support daily start and stop cycles. In order to meet these requirements the author’s company is responding with the development of the single-shaft 1S.W501G combined-cycle power plant. This nominal 400MW class plant will be equipped with the highly efficient W501G gas turbine, hydrogen-cooled generator, single side exhausting KN steam turbine and a Benson™ once-through heat recovery steam generator (Benson™-OT HRSG). The single-shaft 1S.W501G design will allow the plant not only to be operated economically during periods of high demand, but also to compete in the traditional “one-hour-forward” trading market that is served today only by simple-cycle gas turbines. By designing the plant with fast-start capability, start-up emissions, fuel and water consumption will be dramatically reduced. This Reference Power Plant (RPP) therefore represents a logical step in the evolution of combined-cycle power plant designs. It combines both the experiences of the well-known 50Hz single-shaft 1S.V94.3A plant with the fast start plant features developed for the 2.W501F multi-shaft RPP. The paper will address results of the single-shaft 1S.W501G development program within the authors’ company.
ESP Performance Enhancement Analysis by Advanced Modeling Techniques
Authors: Parker K. R. , Plaks N. , Zykov A. M. , Kolchin K. I. , Konavalov V. K.
Published: November 2008

Electrostatic precipitator (ESP) modeling development has reached the point in which internal algorithms completely simulate the operation and particulate collection physics of full-scale units. The modern ESPVI 4.0 series of models by using advanced techniques are able to evaluate changes in a precipitator’s configuration and operation to optimize its performance. The author’s applied these techniques to ESPs’ at the Kashira Power Plant near Moscow, having relatively small specific collector area’s (SCA), whose performance will have to be enhanced to meet emerging standards. Advanced modeling techniques include determining electrode and particle properties, operation below back corona onset, and effects of improved electrodes and electrical conditions. The precipitators with collection efficiencies of 88.4 (without natural gas co-firing) up to 93% (with partial co-firing) are shown to be capable of efficiencies of up to 99% by application of modest changes in configuration and operation. The advanced modeling techniques described in this paper are not only important for Kashira, they are also applicable to other power stations requiring performance optimization.
Temperature and Product Species With Oxygen-Deficient “Air” Fuel Combustion
Authors: Olinger David S. , Lilley David G.
Published: November 2008

Calculations are described that illustrate the adiabatic flame temperature under the following parameter variations: 1. Type of fuel (CHONS amounts specified). 2. Different equivalence ratios. 3. Type of oxidant (air or oxygen). 4. With and without limited dissociation of CO2 and H2O, and more detailed dissociation reactions. 5. With “air” as the oxidant, the volume fraction of oxygen is specified. 6. The inlet temperatures of the fuel and oxidant streams individually are specified. Computations are made of flame temperature and product species composition of fuel combustion with oxygen-deficient air. The fuel is specified by way of its CHONS content and the “air” by way of the volume percent of oxygen, and the other components of “air” (nitrogen, argon, helium and carbon dioxide), each specified by the user. The temperature of each inlet (fuel and “air”) is specified by the user. The methodology and computer code takes as input also the equivalence ratio. Then, results of adiabatic flame temperature are calculated along with the equilibrium product species both with and without dissociation. The computer code is user-friendly with application directly to the new trend toward high temperature air combustion processes, for which some useful results are generated and discussed.
Performance Guarantee and Testing of Steam Turbine Retrofits
Authors: Kearney Phillip J. , Hogg Simon I. , Brown Robert D.
Published: November 2008

The steam turbine retrofit business has grown in recent years, largely due to advances in the aerodynamic design of steam path components, to the point that retrofitting non-OEM equipment is now common place within the industry. This paper discusses different steam turbine retrofit scenarios and how improvements in component performance translate into tangible power and heat rate benefits for plant operators. Methods for guaranteeing the performance of steam turbine retrofit cylinders, that allow the guarantees to be verified by testing approaches that minimize expense and uncertainty are described. Depending on the retrofit solution, guarantees may be simple turbine cylinder efficiency guarantees, performance improvement guarantees or absolute performance guarantees. Different types of testing are appropriate to verify these different forms of guarantee, and they are discussed in the paper.
Due Informative Support for Steam Turbine Operators Keeps Down Detriment From Transients
Authors: Leyzerovich Alexander , Moroz Leonid
Published: November 2008

Transient operating conditions of steam-turbine power units can considerably affect their operating performances. First of all, this emerges in an increase of the operating expenses because of additional fuel expenditures at the transients themselves. Secondly, they entail an increase in the unit’s heat-rate during the subsequent stationary operating conditions because of damages caused by or tied with the transients. Apart from additional fuel costs, the transients have a significant impact on the turbine’s reliability. Equipment failures and forced outages are commonly more probable during the transients, and the equipment lifetime declines due to low-cycle fatigue of the most thermally stressed high-temperature components. The quantitative measure of all these factors to a great degree depends on the operation quality, and the influence of all the above factors can be reduced with the use of advanced on-line informative support for the operator during the transients. The operator should be continuously provided with obvious graphic information about the current temperature and thermal-stress states of the turbine and admissible changes of its operating conditions that can be done without sacrifice of reliability. More often than not, the acting diagrams for the transients can be additionally optimized by way of combined digital solution of direct and reverse unsteady heat conduction problems for so-called “critical” (most thermally stressed) design elements of the turbine. Of significance is also post-operating analysis of the transients to reveal the operator’s errors and prevent their repetition. All these notions refer to both the fossil-fuel and nuclear powerplants. An accumulated experience at different steam-turbine power units proved high effectiveness of these approaches. The developed solutions can be adapted to other equipment types with regard to their design and operation features.
Experiences With Stainless Steel Hollow Conductors for Generator Stator Water Cooling
Authors: Svoboda Robert , Picech Claudio , Hehs Herbert
Published: November 2008

Copper is a traditional material for hollow conductors used in generator stator water cooling. However, stainless steel is a promising and proven alternative for use as hollow conductor material. In 30 years of industry experience, no failures were encountered related to cooling water chemistry with this material. This paper describes the history, electrical and mechanical considerations, water chemistry and materials behavior, and experience with stainless steel hollow conductors. Recommendations are provided on use of high purity water with no restriction on oxygen content.
Common Electronic Platform for the Steam Turbine and Generator Controls: Upgrade Installed at the Mt. Poso Cogeneration Power Station — A Case Study
Authors: Kopczynski Jerry A. , Dickson Bill , Weiss Gerhard J.
Published: November 2008

The scope of modern power plant controls usually includes plant DCS, boiler control and protection, steam/gas turbine governor and protection, auxiliaries control, automatic voltage controller, automatic synchronizer and operator/engineering stations. Usually these control packages come from different manufacturers (OEM). They are typically based on various electronic hardware and software platforms. Different communication protocols often present problems during system integration; and maintenance costs of these various electronic hardware and software platforms are normally greater than that of a stand alone system. Advantages of an integrated, distributed, open architecture, digital system, (Fig. 1) which covers all the power plant needs are discussed in this paper. A common electronic hardware/ software platform allows optimization of the new constructions and upgrades, shorten delivery and commissioning time, and improve availability and safety of the new and upgraded power plants. Specific benefits of this concept are presented in the Mt. Poso controls upgrade Case Study. The common electronic hardware/ software platform installed at Mt. Poso allowed optimization of the upgrade, shortened commissioning time, improved availability, reliability and safety and reduced maintenance cost of the control systems.
Drosophila
Stem Cells Share a Common Requirement for the Histone H2B Ubiquitin Protease Scrawny
Authors: Buszczak Michael , Paterno Shelley , Spradling Allan C.
Published: November 2008

Stem cells within diverse tissues share the need for a chromatin configuration that promotes self-renewal, yet few chromatin proteins are known to regulate multiple types of stem cells. We describe a
Drosophila
gene,
scrawny
(
scny
), encoding a ubiquitin-specific protease, which is required in germline, epithelial, and intestinal stem cells. Like its yeast relative UBP10, Scrawny deubiquitylates histone H2B and functions in gene silencing. Consistent with previous studies of this conserved pathway of chromatin regulation,
scny
mutant cells have elevated levels of ubiquitinylated H2B and trimethylated H3K4. Our findings suggest that inhibiting H2B ubiquitylation through
scny
represents a common mechanism within stem cells that is used to repress the premature expression of key differentiation genes, including Notch target genes.
Direct Measurement of Molecular Mobility in Actively Deformed Polymer Glasses
Authors: Lee Hau-Nan , Paeng Keewook , Swallen Stephen F. , Ediger M. D.
Published: November 2008

When sufficient force is applied to a glassy polymer, it begins to deform through movement of the polymer chains. We used an optical photobleaching technique to quantitatively measure changes in molecular mobility during the active deformation of a polymer glass [poly(methyl methacrylate)]. Segmental mobility increases by up to a factor of 1000 during uniaxial tensile creep. Although the Eyring model can describe the increase in mobility at low stress, it fails to describe mobility after flow onset. In this regime, mobility is strongly accelerated and the distribution of relaxation times narrows substantially, indicating a more homogeneous ensemble of local environments. At even larger stresses, in the strain-hardening regime, mobility decreases with increasing stress. Consistent with the view that stress-induced mobility allows plastic flow in polymer glasses, we observed a strong correlation between strain rate and segmental mobility during creep.
Work Satisfaction and Community Attachment among Fishermen in Southwest Nova Scotia
Authors: Apostle Richard , Kasdan Leonard , Hanson Arthur
Published: November 2008

Social scientists have examined the problem of attachment to the New England fisheries in terms of two interacting influences: work satisfaction, based on questionnaire interviews, and attachment to kin and community, based on ethnographic field research. There is a paucity of equivalent information for the Maritimes. This study replicates the New England work satisfaction studies, and includes additional questions concerning community attachment. We demonstrate that fishermen in southwest Nova Scotia are, in contrast with their New England counterparts, satisfied with all questions about their work (save for the common dissatisfaction with government officials found in both the Nova Scotia and New England samples). In particular, although offshore fishermen in southwest Nova Scotia tend to be somewhat less satisfied than those who fish inshore or both inshore and offshore, they have, by comparison with the New Bedford fishermen, scores that are over the "neutral value" on all time and adventure questions. The underlying factors of job satisfaction are comparable with those in the New England studies, except that the factors in our data are more numerous and simpler to interpret. High job satisfaction is combined with strong community attachments in southwest Nova Scotia.
Survival of Eggs and Alevins of Atlantic Salmon (Salmo salar) in Relation to the Chemistry of Interstitial Water in Redds in some Acidic Streams of Atlantic Canada
Authors: Lacroix Gilles L.
Published: November 2008

Eggs of Atlantic salmon (Salmo salar) were incubated in spawning areas of five streams of mean pH 4.6–6.5. Hatching success (36.6–88.7%) for eggs planted after fertilization in the natural substrate of four acidic streams was highly correlated with the pH (4.5–5.0) of interstitial water, and the LL50 was about pH 4.7. Dissolved oxygen concentrations (>6.0 mg∙L−1) in the interstitial water in these streams were probably not limiting to embryos before hatching. In a near-neutral stream (pH 6.5), the comparatively lower hatching success (5.6–77.0%) was significantly correlated with minimum dissolved oxygen concentration (1.4–9.2 mg∙L−1) in the interstitial water, and the mean survival of embryos was very low (16.2%) at oxygen concentrations <6.0 mg∙L−1. Conditions in the substrate where eggs were incubated until hatching were representative of those in natural salmon redds. In one of the acidic streams (pH 4.8), dissolved oxygen concentrations in the interstitial water were low (2.0–7.6 mg∙L−1) after the hatch, and the emergence of salmon fry from natural redds was minimal, which indicated a low survival of alevins. Estimates of critical pH levels for salmon embryos differ between the laboratory and field approach and are probably site specific because survival in acid waters is determined by acidity, related chemical factors, and changes in water quality within the redd environment.
Cellular Phosphorus Concentration as a Criterion for Trophic Status in Rapidly Flushed Lakes
Authors: Uttormark Paul D. , Hutchins Mark L.
Published: November 2008

By using the steady-state concentration of cellular phosphorus(P) as the indicator of a lake's trophic status, we derived equations that describe the flushing rate at which cellular washout might be expected, and the range of flushing rates in which cellular P concentrations would be reduced significantly below those of total P. Calculated concentrations of cellular P and total P are virtually identical for lakes with flushing rates below about 10 yr−1; at higher rates they may differ substantially. The P mass balances equations we developed consider total P to consist of two components: cellular P and available P. Lakes are treated as completely mixed flow-through reactors with constant P influx. The equations describe conditions in which available P remains in solution until it is removed by algal uptake or lost through sedimentation or outflow. Algae are lost from the system by sedimentation or are discharged through the lake outlet. The transfer of P from available to cellular forms is described by Michaelis–Menten growth kinetics.
The Effect of Production Variability on Financial Risks of Freshwater Prawn Farming in Hawaii
Authors: Samples Karl C. , Leung PingSun
Published: November 2008

A conceptual model of a stochastic production process is proposed which illuminates the business perils associated with shortfalls in yields of aquacultured freshwater prawns. Commercial production data are statistically analyzed within the context of the model to measure the extent to which yield variability engenders financial risks for prawn producers. It is shown that at wholesale prawn prices of US $11.00/kg there is a 50% probability that a representative 8-ha prawn farm utilizing ponds greater than 0.8 surface ha will incur a financial loss in any given year. This probability falls to 30% when ponds smaller than 0.4 surface ha are utilized.
Juvenile Lobster (Homarus americanus) Do Not Require Dietary Ascorbic Acid
Authors: Kean J. C. , Castell J. D. , Trider D. J.
Published: November 2008

We found no dietary ascorbic acid requirement for juvenile lobsters (Homarus americanus) (37–42 mg). The lobsters were fed semipurified diets containing 0, 0.6, 1.2, 2.4, or 12 g L-ascorbic acid/kg dry diet for 20 wk. At termination, the hepatopancreases were removed and assayed for ascorbic acid. There was no significant difference in growth or mortality among any of the dietary treatments. Lobsters fed the deficient diet had hepatopancreatic ascorbic acid levels that were not significantly different from animals fed the supplemented diets. Juvenile lobster, therefore, did not require dietary ascorbic acid under these experimental conditions. We suggest that juvenile lobsters do not require ascorbic acid supplementation in the diet and may be capable of de novo synthesis of this vitamin.
Radiotracer Estimation of Microbial Biomass in Lake Sediment
Authors: Marten Gerald G.
Published: November 2008

The biomass of sediment organisms can be measured by allowing carbon tracer to distribute itself through sediment cores. Application of this method to sediment from Marion Lake, British Columbia, indicated that most of the sediment microorganisms were concentrated in the top 2 cm of sediment, where the total biomass of microorganisms was estimated to be 183 μg C/cm2. The radiotracer estimate compared favorably with independent measurements based on ATP and direct microscopic counts of sediment microorganisms.
Sand deformation under proportional loading
Authors: Negussey D. , Vaid Y. P.
Published: November 2008

A fundamental experimental study of sand behaviour under low stress ratio proportional loading wherein all strain components are contractant is presented. Experimentally observed behaviour under stress conditions of the triaxial test led to a coherent framework for representing proportional loading stress–strain response. The stress–strain relationship formulated incorporates relative density as an inherent independent state variable and does not require appeal to material isotropy. Key words: triaxial test, proportional loading, sand, relative density, energy density, stress increment, strain increment.
Investigation of a coarse alluvial foundation for an embankment dam
Authors: Hanna A. W. , Ambrosii G. , McConnell A. D.
Published: November 2008

Investigation of the coarse alluvial foundation for the Pichi Picun Leufu embankment dam is described and evaluated. Direct and indirect investigation methods are compared and an assessment is made of their relative adequacy in order to gain a realistic understanding of foundation conditions. Indirect methods—dynamic cone penetration testing and shear wave velocity measurement—calibrated by comparative testing in a test embankment, have been found to provide a satisfactory means of evaluating the density of thick alluvial deposits below the water table. Relationships of relative density, penetration resistance, and shear wave velocity are discussed. Dynamic penetration resistance normalized for effective overburden pressure appears to be the more sensitive indicator of changes in material density. Key words: coarse alluvium, relative density, dynamic penetration, shear wave velocity, test embankment, overburden pressure.