bluuebunny/crossref_metadata_2025 huggingface dataset:
Beyond mechanism and dualism: Rethinking the scientific foundations of psychology
Authors: Chiesa Mecca
Published: April 2011

Loss of certainty in science and the philosophy of science has generated number of technical and popular works over the past two decades arguing that contemporary physics paints a relational rather than mechanistic picture of natural phenomena. Assertions that scientific framework based on Newtonian–Cartesian world views are now outmoded challenge scientists to examine basic principles, assumptions and methods informing their interpretive framework. This paper considers some of the scientific foundations of contemporary psychology, especially in terms of its orientation towards calls for a relational framework in which its subject matter might be examined and explained.
Development of spatial memory and spatial orientation in preschoolers and primary school children
Authors: Lehnung Maria , Leplow Bernd , Friege Lars , Herzog Arne , Ferstl Roman , Mehdorn Maximilian
Published: April 2011

The present study addresses the question of what kind of information children use when orientating in new environments, if given proximal and distal landmarks, and how spatial memory develops in the investigated age groups. Ten 5‐year‐old, ten 7‐year‐old and ten 10‐year‐old children were presented with the ‘Kiel Locomotor Maze’, containing features of the Radial Arm Maze and the Morris Water Maze, in order to assess spatial memory and orientation. Children had to learn to approach baited locations only. Task difficulty was equated with respect to the children's age. Training was given until the children reached criterion. During testing, the maze configuration and response requirements were systematically altered, including response rotation, cue rotation, cue deletion and response rotation with cue deletion in order to assess the spatial strategies used by the children. During training and testing, working‐memory errors (WM), reference‐memory errors (RM) and working‐reference memory errors (WR) were recorded. As expected, no difference between age groups appeared during training, thus confirming comparable task difficulty across age groups. During testing, age groups differed significantly with regard to the orientation strategy used. The 5‐year‐olds were bound to a cue strategy, orientating towards local, proximal cues. The 10‐year‐olds mastered all tasks, thus displaying a place strategy, being able to use distal cues for orientation, and were even able to do so after being rotated 180°. The 7‐year‐olds proved to be at an age of transition: five of them were bound to a cue strategy, five children were able to adopt a place strategy. The differences in the orientation strategies used by children of different age groups was reflected by the sum of errors they made, also by RM. WM were found to be rare, especially in older children. We conclude that preschoolers use a cue strategy, that the development of place strategies occurs during primary school age and seems to be complete by the age of 10 years.
Spatial representations acquired from computer models: Cognitive load, orientation specificity and the acquisition of survey knowledge
Authors: Rossano Matt J. , Moak Jay
Published: April 2011

Past research has shown that spatial knowledge acquired from maps is orientation specific while that acquired from direct experience is not. Research using computer model exposure to an environment has sometimes succeeded in eliminating orientation specificity but usually at a cost of generally poor spatial judgment performance on the part of participants. Typically, orientation specificity has been assessed using simulated orientation tests where participants must imagine their locations and facing directions. The current research reduces cognitive load by not using a simulated test of orientation and in doing so succeeds in eliminating orientation specificity while maintaining generally accurate performance after computer model exposure. In tests of survey knowledge, the current research finds evidence that computer model exposure has variable affects on participants over extended periods of time.
Disruption of office‐related tasks by speech and office noise
Authors: Banbury Simon , Berry Dianne C.
Published: April 2011

Three experiments examine what is widely reported to be one of the most common forms of interference in open‐plan office environments—the effect of background noise. Experiment 1 investigates whether office noise (with or without speech) is disruptive to two office‐related tasks: memory for prose and mental arithmetic. The results show that whereas office noise with speech disrupts performance on both tasks, office noise without speech disrupts performance on the mental arithmetic task only. Experiment 2 investigates the memory for prose task more closely by varying the duration and the meaning of the background noise. Experiment 3 examines whether the meaning of speech is important to the disruption of a mental arithmetic task. The results show that both speech and office noise can disrupt performance on memory for prose and mental arithmetic tasks, and the effect is independent of the meaning of the irrelevant speech. These results are presented and interpreted in light of current research and theories regarding the effect of background noise.
Preparing to react in the absence of uncertainty: I. New perspectives on simple reaction time
Authors: Henderson Leslie , Dittrich Winand H.
Published: April 2011

Almost from the inception of psychological enquiry into reaction time (RT), a broad distinction has been drawn between two types of process‐serving performance in RT tasks, namely, the on‐line processes initiated by the arrival of the imperative signal and preparatory processes, which precede the imperative signal and may contribute to performance efficiency. Restriction of attention to on‐line processing fosters the conclusion that the processes serving simple RT are no more than a subset of those involved in choice reactions. If, however, latencies can be reduced by specific preparation then the certitudes of the simple reaction task may invest it with distinctive properties. The possibility of preparation being sensory as well as motor needs to be considered. Until recently, attempts to study preparedness have failed to make controlled comparisons across simple and choice RT. However, recent work has shown that simple reactions have distinctive characteristics that set them apart from minimal choice reactions. The optimization of simple RT seems to depend upon attention‐demanding processes which are probably preparatory in nature. When attention has to be shared with a concurrent task, much of the normal advantage of the simple reaction is lost. Neuropsychological studies suggest that patients may be found with abnormally extended simple RT but spared choice reactions. In these patients, the simple reactions are prolonged relative to those of controls but less vulnerable to imposition of a secondary task. Evidence is beginning to accrue to the effect that some distinctive processing features of simple reactions may be mediated by activity in the frontal lobes.
Computer anxiety: A comparison of pen‐based personal digital assistants, conventional computer and paper assessment of mood and performance
Authors: Tseng Hsu‐Min , Tiplady Brian , Macleod Hamish A. , Wright Peter
Published: April 2011

The recent growth of pen‐based devices, such as the Personal Digital Assistant (PDA), offer mobility and a more natural interface than that of a conventional computer. The feasibility and application of the PDA for mood and cognitive assessment were investigated by examining possible interactions of individual characteristics and administration medium. Previous studies have provided evidence that individual characteristics of ‘computer anxiety’ and ‘private self‐consciousness' divergently covaried with mood scores measured by computer and paper methods. To investigate the relationship between individual characteristics and medium effects, 136 paid participants were allocated to and completed mood assessment tasks and a short battery of cognitive tasks by either the computer, PDA or the paper method. Self‐ratings of mood measured by these three modalities covaried divergently with measures of computer anxiety and private self‐consciousness. In addition, computer anxiety covaried with reaction time on the visual search task obtained on computers, but there was no such relationship when measured by a PDA. These results show that computer anxiety can affect the results of assessments of cognitive function as well as of mood ratings, and suggest that pen‐based systems may have advantages over conventional computers in this respect.
Arousal, erroneous verbalizations and the illusion of control during a computer‐generated gambling task
Authors: Coventry Kenny R. , Norman Anna C.
Published: April 2011

Arousal theories and cognitive theories have been proposed as explanations for both low‐ and high‐frequency gambling. Fifty‐four participants were presented with a computer‐based gambling task in order to examine the relationship between arousal, erroneous verbalizations and the illusion of control. Participants either won mainly at the start, at the end or randomly throughout the task. Predictions of long‐ and short‐term future success were elicited together with arousal levels and verbalizations throughout the task. The results provide support for the importance of the illusion of control applied to gambling tasks, although these effects only occurred with long‐term forecasts. No significant relationships between types of verbalizations and arousal were found, although the task was significantly arousing. Furthermore, no relationships between illusion of control measures and either arousal levels or types of verbalizations were found. Additionally, no differences on any measures were found comparing gambling participants who chase and gamble versus those who do not gamble and/or do not chase. These results are discussed in relation to the explanation of both low‐ and high‐frequency gambling.
Personality traits and personality disorders
Authors: Deary Ian J. , Peter Alistair , Austin Elizabeth , Gibson Gavin
Published: April 2011

The structure of personality disorder traits was examined in a sample of 400 undergraduates who completed the personality disorder questionnaire from the Structured Clinical Interview for DSM‐III–R (SCID‐II). The relations between personality disorder and normal personality traits indexed by the Eysenck Personality Questionnaire–Revised (EPQ–R) were examined. The three‐cluster model of personality traits—as described in the DSM scheme—found equivocal support. Exploratory principal components analysis and confirmatory factor analysis found four broad factors of personality disorder that overlapped with normal personality traits: an asthenic factor related to neuroticism; an antisocial factor associated with psychoticism; an asocial factor linked to introversion–extraversion; and an anankastic (obsessive–compulsive) factor. There is growing agreement about the number and type of broad personality disorder dimensions; similar dimensions may be found in clinical and non‐clinical samples, suggesting that those people with personality disorders differ quantitatively rather than qualitatively from others; and there is substantial overlap between normal and abnormal personality dimensions.
Elastodynamic Inversion of Multilayered Media via Surface Waves—Part I: Methodologies
Authors: Sun Lu , Luo Feiquan , Gu Wenjun
Published: April 2011

A rigorous theoretical foundation for solving elastodynamic inverse problem of multilayered media under an impulse load is established in this paper. The inversion is built upon the forward dynamic analysis of multilayered elastic media using transfer matrix approach, with which displacement continuity is assumed at the interfaces of upper and lower adjacent layers. Formulations for inverse analysis are derived in both the time domain and the complex frequency domain. Least square estimates and nonlinear optimization algorithms are used to implement parameter identification. The proposed theory and formulae can be utilized to develop a computer software for nondestructive evaluation of laminated civil and aerospace structure (highway and airport pavements, bridge decks, soil foundations, aircraft wing, etc.), exploration and dynamic source detection and identification, and petroleum exploration in geophysics.
Propellant Driven Water Acceleration and Its Influence on System Durability
Authors: Kluz K. , Geskin E. S.
Published: April 2011

The work presented investigates numerically and experimentally a formation of high velocity liquid projectiles in the course of the unsteady water acceleration by gaseous products of a propellant combustion. The projectiles were generated in a water launcher, a cylindrical enclosure entailed with a tapered converging nozzle. Previous studies demonstrated that liquid projectiles could be utilized as forming, microforming, welding, and boring tools. It is expected that other applications, such as detonation free explosive neutralization or emission-free coal combustion, are also possible. While the effectiveness of a water projectile is determined directly by its velocity, the principal constraint of the proposed technology is water pressure developed in the launcher. Numerical and experimental studies of the correlation between the water pressure and projectile velocity were performed. The work involved application of a computational fluid dynamics (CFD) package, strain gauge tests, and direct measurement of water projectile velocity. Several assumptions were made for the development of a numerical procedure. The behavior of propellant combustion products, at the pressure approaching 1 GPa, was approximated by the Noble–Abel equation, and the process is assumed to be adiabatic. Moreover, the formalism of the equilibrium thermodynamics is applied to a high pressure (∼1 GPa) supersonic fluid flow. Recorded enclosure strains and projectile velocities confirmed the practical accuracy of the numerical method applied. The major finding of this study is the influence of traveling compression waves on water pressure developed in the barrel and projectile exit velocity. The high pressure, cyclically amplified by wave processes, is a significant engineering obstacle compromising durability of the system.
Elastodynamic Inversion of Multilayered Media via Surface Waves—Part II: Implementation and Numerical Verification
Authors: Luo Feiquan , Sun Lu , Gu Wenjun
Published: April 2011

An effective inverse analysis computer program that integrates nonlinear optimization algorithm and forward dynamic analysis of multilayered medium is developed for inferring structural and material properties (e.g., modulus, thickness, and the number of layers) of the medium. Using dynamic deflection information obtained from forward dynamic analysis of the multilayered medium as a hypothetical deflection measured from the field during pavement nondestructive evaluation (NDE) using falling weight deflectometer, the estimated parameters of the medium are compared with the known true parameters of the medium used to perform the static and forward dynamic analyses. Based on two different multilayered media, a number of important observations and conclusions are made regarding the accuracy and efficiency of the proposed numerical algorithms and developed computer program. The inversion methods presented in this paper show improved NDE results over many of the existing algorithms.
A Novel Similarity Transformation for the Boundary Layer Equations: Solution of Boundary Layer Flows Subjected to Exponential Outer Velocity Profiles
Authors: Karabelas S. J.
Published: April 2011

A new similarity transformation applies to the boundary layer equations, which govern laminar, steady, and incompressible flows. This transformation is proved to be more consistent and more complete than the well known Falkner–Skan transformation. It applies to laminar, incompressible, and steady boundary layer flows with a power-law ue(x)=cxm or exponential profile ue(x)=cemx of the outer velocity. This family of “similar solutions” is resolved for various values of the exponent m. A physical interpretation of these velocity profiles is presented, and conclusions are drawn regarding the tolerance of these boundary layers to flow separation under an adverse pressure gradient.
The Application of FPGA for Anticipated Transients Without Scram Mitigation System
Authors: Tseng Mao-Sheng , Huang Hui-Wen , Chen Ming-Huei , Cheng Tsung-Chieh , Chung Hsiang-Han , Liu Tzeng-Hsi , Yang Wen-Lung , Lee Ming-Chung , Chen Mao-Yuan
Published: April 2011

The digitalized Instrumentation and Control (I&C) system of nuclear power plants (NPP) could provide operator easily Human-Machine Interface (HMI) and more powerful overall operation capability. However, some software errors may cause a kind of Common Cause Failure (CCF). As a consequence, the event of Anticipated Transients Without Scram (ATWS) will occur. In order to assure that the plant can be shutdown safely and to follow the requirements of 10CFR50.62, the utility builds up various ATWS mitigation features in NPP. The features include Fine Motion Control Rod Drive Run In, Alternate Rod Insertion, Standby Liquid Control System, Reactor Internal Pump Trip or Runback, Feedwater Flow Runback and Inhibition of Automatic Depressurization System. This research developed an evaluation method of diverse back-up means for computerized I&C system. A diverse backup of digital I&C system is the most important means to defend against CCF and un-detectable software faults. Institute of Nuclear Energy Research (INER) is developing a computerized I&C test facility, which is incorporated a commercial grade I&C systems with Personal Computer Transient Analyzer (PCTran)/Advanced Boiling Water Reactor (ABWR), a NPP simulation computer code. By taking the technology of Field Programmable Gate Array (FPGA) to implement the methods of ATWS mitigation, the research built up a diverse back-up of digital I&C system to expect to defend against CCF and undetectable software faults. According to the testing and evaluation, the work can be achieved the analysis of Diversity and Defense-in-Depth (D3).
Study of the Corrosion Behavior of Zr-xFe-yCr Alloys in 500°C/10.3MPa Steam
Authors: Wang Jun , Ying Shihao , Miao Zhi , Fan Hongyuan
Published: April 2011

The influence of microstructure on corrosion behavior of Zr-xFe-yCr alloy in 500 °C/10.3MPa steam were studied in this paper by XRD, SEM, EDS, DSC and Hydrogen instrument set. The results showed that several ZrFeCr alloys exhibited protective behavior throughout the test and oxide was stable and protective. The number of precipitates in Zr alloy and the hydrogen pickup of Zr alloy play a good role on corrosion resistance behavior in 500 °C /10.3MPa steam. The Zr1.0Fe0.6Cr has more laves Zr(Fe,Cr)2 precipitate in matrix and has the best corrosion resistance. The Zr0.2Fe0.1Cr has little precipitate, and has the worst corrosion resistance.
Safety Evaluation of the HTTR-IS Nuclear Hydrogen Production System
Authors: Sato Hiroyuki , Ohashi Hirofumi , Tazawa Yujiro , Sakaba Nariaki , Tachibana Yukio
Published: April 2011

Establishment of a safety evaluation method is one of the key issues for the nuclear hydrogen production demonstration since fundamental differences in the safety philosophy between nuclear plants and chemical plants exist. In the present study, a practical safety evaluation method, which enables to design, construct and operate hydrogen production plants under conventional chemical plant standards, is proposed. An event identification for the HTTR-IS nuclear hydrogen production system is conducted in order to select abnormal events which would change the scenario and quantitative results of the evaluation items from the existing HTTR safety evaluation. In addition, a safety analysis is performed for the identified events. The results of safety analysis for the indentified five Anticipated Operational Occurrences (AOOs) and three ACciDents (ACDs) show that evaluation items such as a primary cooling system pressure, temperatures of heat transfer tubes at pressure boundary, etc., do not exceed the acceptance criteria during the scenario. In addition, the increase of peak fuel temperature is small in the most severe case, and therefore the reactor core was not damaged and cooled sufficiently. These results will contribute to the safety review from the government and demonstration of the nuclear production of hydrogen.
Characteristic Optimization of the Double-Tube OTSG
Authors: Wei Xinyu , Zhao Fuyu , Tai Yun , Dai Chunhui
Published: April 2011

The OTSG (Once-Through Steam Generator) is usually used in the integral nuclear power equipment which requires smaller size and better effect of heat transfer. The OTSG with double-side heat transfer component is presented in this paper. The heat transfer component is composed of straight tube outside and helix tube inside. In the both sides of the helix tube, the flow is spirally, therefore, the heat transfer is enhanced. The smaller the pitch, the stronger the spirally flow, the effect of heat transfer is better, but the flow resistance is raised. Especially the increased flow resistance in the secondary side brings a great influence to the pump. The heat transfer region of the secondary fluid are divided into three regions: sub-cooled region, boiling region, and superheated region, the effects of heat transfer induced by the spirally flow vary in different regions. Thus, there is an optimization problem which is to find an optimization pitch of the inner helix tube with the best effect of heat transfer and the minimum flow resistance. Based on analyzing the effects of the pitch on heat transfer enhancement and flow resistance, the pitch is optimized by the constrained nonlinear optimization method.
An Evaluation of a Direct Corium Cooling Method for the Ex-Vessel Melt Retention
Authors: Ha Kwang Soon , Kim Hwan Yeol , Kim Jongtae , Park Jong Hwa
Published: April 2011

An evaluation of the ex-vessel core catcher system of a sample advanced light water reactor was presented. The core catcher was designed to cool down the molten corium through a combined injection of water and gas from the bottom of the molten corium, which could be effective in the reduction of rapid steam generation and in the suppression of a steam explosion. By using the MELCOR code, a scenario analysis was performed for a representative severe accident scenario of the ALWR, that is, the 6-inches large break loss of coolant accident without safe injection. The corium spreading regime was estimated by an asymptotic calculation. The composition of the molten corium, the decay power level, and the sacrificial concrete ablation depth with time were obtained by a sacrificial concrete ablation analysis. The corium cooling history in the core catcher during the coolant injection was evaluated to calculate the temporal steam generation rate by considering an energy conservation equation. These were used as the major inputs for the temporal calculations of containment pressure which was performed by using the GASFLOW code. Several cases with change of water and gas injection rates were calculated. It was confirmed that the bottom water injection system was an effective corium cooling method in the ex-vessel core catcher to preclude a possible steam explosion and to suppress the quick release of steam.
Using Microplane Material Model for Concrete in Soft Missile Impact Analysis
Authors: Ka¨hko¨nen Jukka , Varpasuo Pentti
Published: April 2011

The paper describes basis of a microplane concrete material model which was implemented in a commercial FE -code using user subroutine interface. The material model is called M4. The motivation for this implementation was a need for a concrete model which would perform well in a soft missile impact analysis. Numerical integration over the surface of a unit sphere is crucial to microplane material models. We tested our microplane implementation using several numerical integration formulas presented in literature. The two fairly simple test cases described in this paper revealed clearly the numerical anisotropy induced by the integration formulations. The impact problem was a medium size, medium velocity soft missile impact test case from an international research program. We compared our implementation of M4 model to a tensorial based damage plasticity concrete model and found out that the results were almost identical. However, the numerical results did not agree well with the measurements in this test case. We concluded this disagreement might be consequence of nonlinear phenomena beyond material constitutive relations.
Seismic Fragility Study for High-Pressure Emergency Cooling Water Tanks of Loviisa Nuclear Power Plant
Authors: Ka¨hko¨nen Jukka , Varpasuo Pentti
Published: April 2011

The paper studies the fragility of high-pressure emergency cooling water tanks in Loviisa Nuclear Power Plant located on the elevation +25.40 in the reactor building. The seismic fragility is defined as the conditional probability of its failure given a value of the response parameter, such as peak ground acceleration. Using the lognormal-distribution assumption, the fragility (i.e., the probability of failure, f′) at any non-exceedance probability level Q can be derived as Equation1f′=Φ[(ln(a/A¯)+βUΦ−1(Q))/βR] where Q = P(f<f′|a) is the probability that the conditional probability f is less than f′ for a peak ground acceleration a. A is the median ground acceleration capacity, βR is the logarithmic standard deviation representing the randomness about A, and βU is the logarithmic standard deviation representing the uncertainty. The quantity Φ(.) is the standard Gaussian cumulative distribution function. In order to assess the fragility of the tanks the strain time histories for tank supports and piping nozzles were calculated using the joint structural-equipment model. The ground motion response spectra shape used in the structural response analysis has been taken from the YVL 2.6 – guide [1]. This shape represents the envelope spectrum for Southern Finland corresponding to the median annual frequency of 10−5. The sampling of the model properties was carried out with the aid of the Latin hypercube sampling method. In order to find the failure modes the strain time histories were calculated for the piping nozzles and for support structures of the tanks. Since strain is the best measure of energy absorption, energy limited events need to be based on the strain acceptance criteria. The adopted failure limit is the cumulated plastic strain of 8% in the tank sheet metal or in the supporting structures. This failure limit has taken from the reference [2]. The end result of the study is the presentation of the median fragility curve for the tanks as well as 95% and 5% fractile curves.
A Fault Diagnosis Expert System for LHCD System on EAST
Authors: Feng Jianqiang , Shan Jiafang , Wang Mao
Published: April 2011

Lower hybrid current drive (LHCD) is an efficient method for noninductive current drive in fusion devices. The LHCD system has been constructed on the Experimental Advanced Superconduct Tokamak (EAST). It is a complex system due to lots of devices involved. Each device has possibility of faults, which causes great difficulties in fault diagnosis. Consequently, a fault diagnosis expert system is essential for a safe and steady operation of the LHCD system. This paper proposes an expert system called LFDES (lower hybrid current drive fault diagnosis expert system) to aid operators in diagnosing and analyzing abnormal situations of the LHCD system. After a brief description of the structure of LHCD system, the LFDES architecture, the knowledge base, the inference engine and the database are presented in detail. Based on an empirical knowledge, the diagnostic tree of LHCD system is built. A fuzzy group multiple attribute decision making method is used to determine the priorities of nodes in the diagnostic tree. KDevelop tool, QT Designer tool and Linux operation system have been used in developing the proposed system. In the study, satisfactory results were obtained. The analyses of the results indicated that LFDES can provide reliable, efficient and economical service.
Fluctuating Pressure Generating in BWR Main Steam Lines Acoustic Excited by Safety Relief Valve Stub Pipes and Dead Legs
Authors: Takahashi Shiro , Okuyama Keita , Tamura Akinori , Ohtsuka Masaya , Tsubaki Masaaki , Yasuhiro Mabuchi , Kubota Teppei , Ogawa Yukio , Inada Fumio , Morita Ryo
Published: April 2011

During operation, the BWR-3 steam dryer in the Quad Cities Unit 2 Nuclear Power Plant was damaged by high cycle fatigue. The dryer failure was attributed to flow-induced acoustic resonance at the stub pipes of safety relief valves (SRVs) in the main steam lines (MSLs). The acoustic resonance was considered to be generated by interaction between the sound field and an unstable shear layer across the closed side branches with SRV stub pipes. We HITACHI and CRIEPI have started a research program on BWR dryers to develop their loading evaluation methods. Moreover, it has become necessary to evaluate the dryer integrity of BWR-5 plants in particular which are the main type of BWR in Japan. In the present study, we used 1/10-scale BWR tests and analyses to investigate the flow-induced acoustic resonance and characteristics of fluctuating pressure in MSLs. The test apparatus consisted of a steam dryer, a steam dome and 4 MSLs with 20 SRV stub pipes. A finite element method (FEM) was applied for the calculation of three-dimensional wave equations in acoustic analysis. We demonstrated that remarkable fluctuating pressures occurred in high and low frequency regions. Intensity of three peaks observed in the spectrum of fluctuating pressure in MSLs was increased with St. High frequency fluctuating pressures were generated by the flow-induced acoustic resonance in the SRV stub pipes. Low frequency fluctuating pressures were excited by the acoustic resonance in the dead leg. Frequency of fluctuating pressure generating in the SRV stub pipe was changed with St. On the other hand, frequency of fluctuating pressure excited by dead leg was almost constant. Fluctuating pressure in low frequency range increased gradually with flow velocity and its intensity was roughly proportional to the square of flow velocity. The flow-induced acoustic resonance did not occur for St larger than 0.6 in the BWR MSLs for both low and high frequency ranges. Operating conditions of the BWR-5 from 100 to 115% were in the range of St larger than 0.6, so intense acoustic resonance would not occur in the BWR MSLs.
Parameters Influencing the Secondary Hydrogenation of Zr-Sn and Zr-Nb Alloys During Steam Oxidation Under LOCA and Severe Accident Conditions
Authors: Grosse Mirco K. , Steinbrueck Martin , Stuckert Juri
Published: April 2011

The parameters influencing secondary hydrogen uptake can be divided into two groups: material properties and process parameters. The first group includes for instance the steam oxidation kinetics, the oxide morphology and the hydrogen diffusion through the oxide layer. The second group covers for instance the temperature, the total pressure, the gas flow type and rates, the cladding area and the filling of the rods. Together with a theoretical view on the influence of different parameters on the hydrogen uptake of zirconium alloys experimental results from separate-effect tests, large-scale QUENCH tests and in-situ neutron radiography investigations of the hydrogen uptake during steam oxidation will be presented. The hydrogen concentrations in specimens made from commonly used cladding materials were determined by quantitative analysis of neutron radiographs. Information obtained from ex- and in-situ steam oxidation experiments will be given. The presentation of the experimental results will be focused on the influence of oxidation time and temperature, of the oxide layer morphology, the sample geometry and of the gas flow rates on the hydrogen concentration of the remaining metal phases. Differences between Zr-Sn, Zr-Nb and Zr-Sn-Nb alloys will be discussed.
Economic Analysis on MOX Fuels
Authors: Jia Shizhuang , Cao Liangzhi , Wu Hongchun
Published: April 2011

This paper proposes and explaines the economic model of MOX fuel used in PWR versus the one used in FBR, considering the fuel flow and the cash flow of fuel cycle. We take the point of view of a firm that is deciding whether to build a new PWR or a FBR, according to its fuel cost and annual cost, ignoring the capital cost and other costs. In order to make the results more practicable, in the future, the economic analysis will provide three sets of costs, which are the best, central and worst cases for the two reactors. The corresponding results, provide analysis of the sensitivity of the costs versus various parameters and other contents.
FCC-NG: The AREVA Safe Fresh Fuel Shipping Cask to Deliver the Future EPR™ Reactors
Authors: Doucet M. , Faye P. , Faignet Ch. , Babut R. , Landrieu M. , Marvaud F. , Romanet G.
Published: April 2011

AREVA as a worldwide PWR fuel provider has to have a fleet of fresh UO2 shipping casks being agreed within a lot of countries and to accommodate foreseen EPR™ Nuclear Power Plants fuel buildings. To reach this target the AREVA NP Fuel Sector together with TN International (a subsidiary of AREVA NC) decided to develop an up to date shipping cask gathering experience feedback of the today fleet and an improved safety allowing the design to comply with international regulations (NRC and IAEA) and other local foreign Safety Authorities requirements. Based on pre design features a safety case was set up to highlight safety margins. Criticality hypothetical accidental assumptions were defined: • Preferential flooding, • Fuel rod array expansion (so called “bird caging” effect), • Fuel sliding, • Neutron absorber penalty, • …. The French criticality code package CRISTAL is used to check several configurations reactivity and derived safety margins. The CRISTAL code package relies on a wide validation process helping defining uncertainties as required by regulations in force. The shipping cask, containing two fuel assemblies, is designed to maximize fuel isolation inside the cask and with neighboring ones even for large array configuration cases. Few and proven industrial products are used: • Stainless steel for the structural frame, • Balsa wood for impact limiters, • BORA® resin as neutron absorber. The cask is designed to handle mainly the EPR™ fuel assembly type and may be extended to other contents such as APWR fuel assembly type. After a brief presentation of the computer codes and the description of the shipping cask, the CRISTAL calculation results as well as the applied uncertainties will be discussed.
Research on Fuzzy Decoupled and Coordinated Control of Nuclear Power Plant
Authors: Zhang Wei , Xia Guoqing , Ai Ming , Fu Minyu , Cai Hegao
Published: April 2011

The mathematic models of reactor, once-through steam generator and turbine are built based on the mass, energy and momentum conservation theorem. Because of serious coupling and different dynamic characteristic, the coordinated control that solves big system problem is presented to apply into the nuclear power plant after researching deeply the variety feature and coupling relation of primary parameters of the nuclear power plant. The coordinated control system is filled with manage control, coordinated control and bottom controller. The simulation is processed by changing turbine load. Compared with non-coordinated control system, the coordinated control system improves briefly the dynamic feature of nuclear power plant. The fuzzy decoupled control strategy between once-through steam generator and turbine is proposed. The fuzzy decoupled frame including a compensator and design method of the decoupled compensator are given, the fuzzy rules are applied in the decoupled compensator. Finally, a fuzzy decoupled control system is designed in detail with a two inputs and two outputs’ system, which is applied in the coordinated control system of the nuclear power plant. The simulation results show that the coordinated control system based on the decoupled strategies is better than the coordinated control system, which weakens the couple connection, reduces the fluctuation of exit steam pressure by adjusting the feedwater flux.
Study of Template Measurement of Plutonium Pit Based on Gamma-Ray Detection
Authors: Zhang Changfan , Gong Jian , Teng Junrui , Liu Suping
Published: April 2011

Template measurement is an important method in deep nuclear disarmament. The gamma-ray spectrum of Plutonium pit shows unique property due to age, abundance, amounts and thickness of the Plutonium pit; that is, same designed pits yield similar gamma-ray spectra while different design give distinct spectra. Useful information is extracted from gamma-ray spectrum generated by the reliable Plutonium pit radiation as ‘template’. Comparison of the data from inspected objects with the template can give conclusion whether they are of the same type. This paper studies how to choose template data from gamma-ray spectrum and discusses the limits of the gamma-ray measurement. Because of the strong self-absorption of Plutonium, some characteristics of Plutonium pit can’t be identified only by gamma spectrum. MCNP simulation was employed to prove that in some cases, template depending on gamma-ray spectrum from the reliable Plutonium pit alone can’t effectively distinguish the spurious objects. And a further approach indicates that enhancing neutron counting rate of spontaneous fission of Plutonium can improve the problem. Neutron counting rate can be indirectly acquired by spontaneous fissile neutrons bombarding a 10B target. 478 keV γ rays are concomitant with the nuclear reaction 10B(n,α)7Li* from 7Li* nuclei’s deexcitation. Neutron information is gathered by detecting 478 keV γ photons. Using HPGe γ detector can both detect γ-ray spectrum and acquire neutron counting rate. This method efficiently increases confidence of template measurement and also ensures the dismantling process without revealing sensitive nuclear warhead design information.
Asymmetry Investigation on Single Phase Flow in Inverted U-Tubes of Steam Generator Under the Condition of Natural Circulation
Authors: Wang Chuan , Yu Lei
Published: April 2011

In order to study the reverse flow characteristics in U-tubes of steam generator in the natural circulation case, the code RELAP5/MOD3.3 is used to model and calculate single-phase water flow for PWR under some typical operating conditions in the natural circulation case. The U-tubes of steam generator are classified according to their length and then are divided into different nodes and flow lines. The calculated results show that reverse flow exists in some inverted U-tubes of the steam generator, the natural circulation capacity of the primary coolant circuit system declines and the calculated net mass flux of the natural circulation accords with the experimental data. The traditional lumped parameter method can not simulate the reverse flow characteristics in inverted U-tubes and its result is much greater than the experimental data. When the steam generator outlet pressure is higher than inlet pressure, and gravitational pressure drop is lower than the total of frictional pressure drop and area change pressure drop, the reverse flow will occur. As to the nuclear power plant described in this paper, the mass flux of the shorter U-tubes drops more quickly and at last reverse flow will occur. The temperature distribution is uniform in inverted U-tubes, and it is almost identical with that of SG in secondary side. The occurrence of reverse flow can be judged by that whether the steam generator inlet temperature is lower than reactor outlet temperature obviously. It is indicated that reverse flow occurred in the U-tubes of the steam generator reduces the mass flux in the natural circulation system.
Fragmentation of a Single Molten Stainless Steel and Aluminum Droplet Penetrating a Sodium Pool
Authors: Zhang Zhi-gang , Sugiyama Ken-ichiro
Published: April 2011

In order to clarify the fragmentation of molten core structural material (stainless steel) and molten metallic fuel and claddings on liquid phase formed by metallurgical reactions (liquefaction temperature = 650°C) during core disruptive accidents (CDAs), the present study focuses on the fragmentation of single molten stainless steel (316SS) and aluminum droplet penetrating a sodium pool. The temperatures of 3–5g molten aluminum droplets were 1002 to 1399°C, and the sodium pool was about 300°C. The instantaneous contact interface temperatures (Ti) between the molten aluminum droplets and liquid sodium were calculated to be from 741°C below the boiling point of sodium (Tc,bp) to 1019°C above Tc,bp. The temperatures of 5g molten 316SS droplets were 1510 to 1706°C, and the temperatures of sodium pool vary about 300–400°C. The Ti values between the molten 316SS droplets and liquid sodium were calculated to be from 916 to 1082°C. Fragmentation of the single molten aluminum droplet was clearly observed even at Ti ≪ Tc,bp. When Ti is approximately equal to or higher than the boiling point, the intensive fragmentation of droplet was clearly observed independent of Wea condition. Fragmentation of the single molten 316SS droplet was clearly observed even at Ti below its melting point. The Dm values of aluminum and 316SS droplets with relatively high Wea tend to be lower than those of droplets with relatively low Wea under the relatively low Ti condition. These results indicate the fragmentation of the molten core structural material and eutectic alloy fuels in liquid phase formed by the metallurgical reactions could possibly occur under the low Ti condition below and above the sodium boiling point, which is promising to assure the termination of accidents in CDAs and useful to the core design with enhanced safety in FBRs.
Study on Methods of Calculating Heat Transfer Coefficient of Supercritical Water With Grey Theory
Authors: Liu Xiaozhuang , Zhou Tao , Li Zhenyang , Wang Handing
Published: April 2011

Heat transfer coefficient is an important feature factor in describing SCWR. Using grey theory and multiple regression, writing code with MATLAB with considering temperature and enthalpy of coolant, heat flux and system pressure, establish GM(1.1), GM(1,3) and multiple regression models of heat transfer coefficient of supercritical water. analyzing the impact of temperature and enthalpy of coolant, heat flux, pressure on the changes of heat transfer coefficient in SCWR. Grey model generally summarize the experimental data. and its calculation results are compared with the results of regression model, which shows grey model can forecast the changes of heat transfer coefficient better, provides new methods of fitting and forecasting heat transfer coefficient of supercritical water.
Study on Pressure Loss Induced by Complicated Flow Through Lower Plenum of BWR
Authors: Watanabe Shun , Abe Yutaka , Kaneko Akiko , Watanabe Fumitoshi , Tezuka Kenichi
Published: April 2011

One of the strategies of cost reduction of nuclear power generation is the increase of power outputs. Especially, in order to achieve performance upgrade of Advanced Boiling Water Reactor (ABWR), it is extremely important to evaluate coolant flow in the lower plenum of ABWR. With the plenty construction in the lower plenum, it is thought that the flow structure is complicated. Moreover, according to the previous studies, there is strong evidence that vortexes arise around side entry orifice when coolant flows in there. Such complicated flow may affect the pressure loss (differential pressure in the lower plenum) and the coolant flow distribution to each core fuel assemblies, and consequently it would influence advancement of fuel economics. Although the simulation results by a CFD code can predict such complicated flow in the lower plenum, the accuracy of simulation data are not enough. Hence, the present study is focusing on the establishment of the benchmark of CFD code by using the visualization method in the lower plenum of ABWR. The objective of the present study is to investigate correlation between the structure of vortexes and complicated flow in upstream of core support beam, and the effect of such fluid behavior to the differential pressure. In the constructed model of the lower plenum of ABWR, velocity profiles were measured by LDV (Laser Doppler Velocimetry) and PIV (Particle Image Velocimetry) techniques. And differential pressure of constructed model is measured by differential pressure instrument. Each measurement was worked out in the range of Reynolds number from 103 to 104. It was found from the LDV measurement that the velocity at the center of the test section was faster than that near the wall in upstream. In downstream, the velocity profiles showed the tendency to be flat in the core support beam. Vortexes were observed around side entry orifice by PIV measurement. Concerning differential pressure, it is necessary to examine correlation between complicated flow structure and differential pressure. Thus in the present study, the differential pressure distribution of constructed model is experimentally investigated.
A Study About Human Workload Forecasting Method of Nuclear Power Plant
Authors: Jiang Guojin , Gu Pengfei , Sun Yongbin
Published: April 2011

In the past, the human machine interface is not computerized and the analysis tools are lack. So that most of previous researches of operator performance focused on the performance of individual operator rather than on the team performance. The relationships between team performance and individual performance are very close, but the team performance is not exactly equal to the sum of individual performance. The complexity of team performance evaluation is much higher than that of individual performance evaluation. Along with the development of new technology, especially the computerized technology, such as eye tracking tool and video recorder, team performance could be observed and measured. In NPP (Nuclear Power Plant), the operator performance of team work is closed to the safety of the whole plant. So the operators needed to be paid high attention to team performance. In order to improve the operator performance (including individual and team performance) base on the computerized human machine interface, this study bends to develop a real-time warning model for assessing team performance through the mental workload and human reliability evaluation. According to the analysis result, it could be as reference to modify the design about human machine interface in order to increase system safety and team performance of NPP.
Radiographic X-Ray Spot Size Measurement With Bread Piece
Authors: Gao Yi , Zhang Zhong
Published: April 2011

The principle of radiographic X-ray spot size measurement with Bread piece was presented. The output responses of the Bread piece for uniformly-distributed X-ray sources are calculated numerically. The relationship between FWHM of the response curve and the spot size is obtained. Preliminary experiments were performed on the inductive voltage adder (IVA), and the Bread piece is used to measure the axial spot size of the rod-pinch diode (RPD) radiographic source. Under the hypothesis of uniformly-distributed line source, the axial spot size value is obtained, consistent with the measuring result of the pinhole camera, verifying the applicability of the Bread piece for radiographic X-ray spot size measurement.
Accident Sequence Precursor Analysis of Daya Bay and Lingao Nuclear Power Plants
Authors: Liu Pingping , Xi Haiying
Published: April 2011

Firstly this article describes how to analyze accident sequence precursor in U.S. nuclear regulatory commission. Following this method, the licensee operational events, internal operational events and inspection reports of Daya Bay and Lingao Nuclear Power Plants were reviewed to identify the precursors with support of probabilistic safety assessment. All the identified precursors were calculated, documented and ranked. Then the trends on precursors can be obtained. Finally this article analyzes the trends available and gains many beneficial insights.