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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Nuclear Engineering and Technology
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Journal DOI :
Korean Nuclear Society
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Volume & Issues
Volume 31, Issue 6 - Dec 1999
Volume 31, Issue 5 - Oct 1999
Volume 31, Issue 4 - Aug 1999
Volume 31, Issue 3 - Jun 1999
Volume 31, Issue 2 - Apr 1999
Volume 31, Issue 1 - Feb 1999
Selecting the target year
Etching Reaction of
Mixture Gas Plasma
Kim, Yongsoo ; Jinyoung Min ; Kikwang Bae ; Myungseung Yang ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 133~138
Research on the etching reaction of UO
gas mixture plasma is carried out. The reaction rates are investigated as a function of CF
ratio, plasma power, and substrate temperature. It is found that there exists an optimum CF
ratio around 4:1 at all temperatures up to 37
and surface analysis using XPS X-ray Photoelectron Spectroscopy) confirms the result. Peak rate at the optimum gas composition increases with increasing temperature. Highest rate obtained in this study leaches 1050 monolayers/min. at 37
under r. f. power of 150 W, which is equivalent to about 0.5
/min. The rate also increases with increasing r. f. power, thus, higher power and higher substrate temperature will undoubtedly raise the etching reaction rate much further. This reaction seems to be an activated process, whose activation energy will be derived in the following experiments.
Swelling Pressures of a Potential Buffer Material for High-Level Waste Repository
Lee, Jae-Owan ; Cho, Won-Jin ; Chun, Kwan-Sik ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 139~150
The swelling pressure of a potential buffer material was measured and the effect of dry density, bentonite content and initial water content on the swelling pressure was investigated to provide the information for the selection of buffer material in a high-level waste repository. Swelling tests were carried out according to Box-Behnken's experimental design. Measured swelling pressures were in the wide range of 0.7 Kg/
to 190.2 Kg/
under given experimental conditions. Based upon the experimental data, a 3-factor polynomial swelling model was suggested to analyze the effect of dry density, bentonite content and initial water content on the swelling pressure The swelling pressure increased with an increase in the dry density and bentonite content, while it decreased with increasing the initial water content and, beyond about 12 wt.% of the initial water content, levelled off to nearly constant value.
Drift Diffusion of Radiation-produced Point Defects to Edge Dislocation
Park, S. S. ; K. O. Chang ; Park, S. P. ; Kim, C. O. ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 151~156
Under the heavy irradiation of crystalline materials when the production and the recombination of interstitials and vacancies are included, the diffusion equations become nonlinear. An effort has been made to arrange an appropriate transformation of these nonlinear differential equations to more solvable Poisson's equations, finally analytical solutions for simultaneously calculating the concentrations of interstitials and vacancies in the angular dependent Cottrell's potential of the edge dislocation have been derived from the well-known Green's theorem and perturbation theory.
Mathematical Verification of a Nuclear Power Plant Protection System Function with Combined CPN and PVS
Koo, Seo-Ryong ; Son, Han-Seong ; Seong, Poong-Hyun ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 157~171
In this work, an automatic software verification method for Nuclear Power Plant (NPP) protection system is developed. This method utilizes Colored Petri Net (CPN) for system modeling and Prototype Verification System (PVS) for mathematical verification. In order to help flow-through from modeling by CPN to mathematical proof by PVS, an information extractor from CPN models has been developed in this work. In order to convert the extracted information to the PVS specification language, a translator also has been developed. ML that is a higher-order functional language programs the information extractor and translator. This combined method has been applied to a protection system function of Wolsong NPP SDS2(Steam Generator Low Level Trip). As a result of this application, we could prove completeness and consistency of the requirement logically. Through this work, in short, an axiom or lemma based-analysis method for CPN models is newly suggested in order to complement CPN analysis methods and a guideline for the use of formal methods is proposed in order to apply them to NPP Software Verification and Validation.
Comparison of Matrix Exponential Methods for Fuel Burnup Calculations
Oh, Hyung-Suk ; Yang, Won-Sik ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 172~181
Series expansion methods to compute the exponential of a matrix have been compared by applying them to fuel depletion calculations. Specifically, Taylor, Pade, Chebyshev, and rational Chebyshev approximations have been investigated by approximating the exponentials of bum matrices by truncated series of each method with the scaling and squaring algorithm. The accuracy and efficiency of these methods have been tested by performing various numerical tests using one thermal reactor and two fast reactor depletion problems. The results indicate that all the four series methods are accurate enough to be used for fuel depletion calculations although the rational Chebyshev approximation is relatively less accurate. They also show that the rational approximations are more efficient than the polynomial approximations. Considering the computational accuracy and efficiency, the Pade approximation appears to be better than the other methods. Its accuracy is better than the rational Chebyshev approximation, while being comparable to the polynomial approximations. On the other hand, its efficiency is better than the polynomial approximations and is similar to the rational Chebyshev approximation. In particular, for fast reactor depletion calculations, it is faster than the polynomial approximations by a factor of ∼ 1.7.
onto Goethite and Kaolinite: Mechanistic Modeling Approach
Jinho Jung ; Lee, Jae-Kwang ; Cho, Young-Hwan ; Keum, Dong-Kwon ; Hahn, Pil-Soo ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 182~191
The sorption of UO
onto goethite and kaolinite under various experimental conditions was successfully interpreted using surface complexation modeling (SCM). The SCM approach used in this work is the triple-layer model (TLM) in which weakly bonded ions are modeled as outer-sphere (ion-pair) complexes and strongly bonded ions as inner-sphere (surface coordination) complexes. The change of ionic strength did not affect the U(VI) sorption onto goethite, thus the formation of inner-sphere surface complexes, (FeO)
was assumed to simulate the effects of ionic strength and goethite concentration. On the other hand, the U(VI) sorption onto kaolinite showed ionic strength dependence, thus the formation of AlO-UO
(outer-sphere complex) and SiO(UO
(inner-sphere complex) was assumed to simulate the experimental data. In the presence of carbonates, the sorption of U(VI) onto kaolinite decreased in the weakly alkaline pH range. This was well simulated assuming the formation of a outer-sphere surface complex, A1OH
. Since SCM approach uses thermodynamic data such as surface complexation constants, it is more predictive than empirical modeling approach in which conditional values such as partition coefficient are used. used.
Feedwater Flowrate Estimation Based on the Two-step De-noising Using the Wavelet Analysis and an Autoassociative Neural Network
Gyunyoung Heo ; Park, Seong-Soo ; Chang, Soon-Heung ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 192~201
This paper proposes an improved signal processing strategy for accurate feedwater flowrate estimation in nuclear power plants. It is generally known that ∼2% thermal power errors occur due to fouling Phenomena in feedwater flowmeters. In the strategy Proposed, the noises included in feedwater flowrate signal are classified into rapidly varying noises and gradually varying noises according to the characteristics in a frequency domain. The estimation precision is enhanced by introducing a low pass filter with the wavelet analysis against rapidly varying noises, and an autoassociative neural network which takes charge of the correction of only gradually varying noises. The modified multivariate stratification sampling using the concept of time stratification and MAXIMIN criteria is developed to overcome the shortcoming of a general random sampling. In addition the multi-stage robust training method is developed to increase the quality and reliability of training signals. Some validations using the simulated data from a micro-simulator were carried out. In the validation tests, the proposed methodology removed both rapidly varying noises and gradually varying noises respectively in each de-noising step, and 5.54% root mean square errors of initial noisy signals were decreased to 0.674% after de-noising. These results indicate that it is possible to estimate the reactor thermal power more elaborately by adopting this strategy.
Effect of Rotary Inertia of Concentrated Masses on the Natural Vibration of Fluid Conveying Pipe
Kang, Myeong-Gie ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 202~213
Effects of the rotary inertia of concentrated masses on the natural vibrations of fluid conveying pipes have been studied by theoretical modeling and computer simulation. For analysis, two boundary conditions for pipe ends, simply supported and clamped-clamped, are assumed and Galerkin's method is used for transformation of the governing equation to the eigenvalues problem and the natural frequencies and mode shapes for the system have been calculated by using the newly developed computer code. Moreover, the critical velocities related to a system instability have been investigated. The main conclusions for the present study are (1) Rotary inertia gives much change on the higher natural frequencies and mode shapes and its effect is visible when it has small value, (2) The number and location of nodes can be changed by rotary inertia, (3) By introducing rotary inertia, the second natural frequency approaches to the first as the location of the concentrated mass approaches to the midspan of the pipe, and (4) The critical fluid velocities to initiate the system unstable are unchanged by introduction of rotary inertia and the first three velocities are
, and 3
for the simply supported pipe and 2
, 8.99, and 12.57 for the clamped-clamped pipe.
Flexural Vibration of Clamped and Simplv Supported Sectorial Plates with Combinations of Simply Supported and Free Radial Edges
Han, Bong-Ko ; Kim, Joo-Woo ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 214~225
An accurate method is presented for flexural vibrations of sectorial plates having simply supported-free and free-free radial edges, when the circular edge is either clamped or simply supported. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets consist of : (1) mathematically complete algebraic-trigonometric polynomials which gurantee convergence to exact frequencies as sufficient terms are retained, and (2) comer functions which account for the bending moment singularities at re-entrant comer of the radial edges having arbitrary edge conditions. Accurate (at least four significant figures) frequencies and normalized contours of the transverse vibratory displacement are presented for the spectra of corner angles [90
(complete circular)] causing a re-entrant comer of the radial edges. Future solutions drawn from alternative numerical procedures and finite element techniques may be compared with these accurate results.
Analysis of Several Digital Network Technologies for Hard Real-time Communications in Nuclear Plant
Song, Ki-Sang ; No, Hee-Cheon ; Kim, Dong-Hun ; Koo, In-Soo ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 226~235
Applying digital network technology for advanced nuclear plant requires deterministic communication for tight safety requirements, timely and reliable data delivery for operation-critical and mission-critical characteristics of nuclear plant. Communication protocols, such as IEEE 802/4 Token Bus, IEEE 802/5 Token Ring, FDDI, and ARCnet, which have deterministic communication capability are partially applied to several nuclear power plants. Although digital communication technologies have many advantages, it is necessary to consider the noise immunity from electromagnetic interference (EMI), electrical interference, impulse noise, and heat noise before selecting specific digital network technology for nuclear plant. In this paper, we consider the token frame loss and data frame loss rate due to the link error event, frame size, and link data rate in different protocols, and evaluate the possibility of failure to meet the hard real-time requirement in nuclear plant.
An Improved Mechanistic Model to Predict Critical Heat Flux in Subcooled and Low Quality Convective Boiling
Kwon, Young-Min ; Chang, Soon-Heung ;
Nuclear Engineering and Technology, volume 31, issue 2, 1999, Pages 236~255
An improved mechanistic model was developed to predict a convective boiling critical heat flux (CHF) in the vertical round tubes with uniform heat fluxes. The CHF formula for subcooled and low quality boiling was derived from the local conservation equations of mass, energy and momentum, together with appropriate constitutive relations. The model is characterized by the momentum balance equation to determine the limiting transverse interchange of mass flux crossing the interface of wall bubbly layer and core by taking account of the convective shear effect due to the frictional drag on the wall-attached bubbles. Comparison between the present model predictions and experimental CHF data from several sources shows good agreement over a wide range of How conditions. The present model shows comparable prediction accuracy with the CHF look-up table of Groeneveld et al. Also the model correctly accounts for the effects of flow variables as well as geometry parameters.