Research Interests:
Research Interests:
The creep properties for the Hastelloy-X alloy which is one of candidate alloys for a high temperature gas-cooled reactor are presented. The creep data was obtained with different stresses at 950oC, and a number of the creep data was... more
The creep properties for the Hastelloy-X alloy which is one of candidate alloys for a high temperature gas-cooled reactor are presented. The creep data was obtained with different stresses at 950oC, and a number of the creep data was collected through literature surveys. All of the creep data were combined together to obtain the creep constants and to predict a long-term creep life. In the Norton’s creep law and the Monkman-Grant relationship, the creep constants, A, n, m, and m’ were obtained. Creep master curves based on the Larson-Miller parameter were presented for the standard deviations of 1σ, 2σ and 3σ. Creep life at each temperature was predicted for a longer-time rupture above 105 hours. Failure probability was also estimated by a statistical process of all the creep rupture data.
Research Interests:
It is shown that the Shanks sequence -transformation and the conventional extrapolation method are theoretically related. The -transformation method is then applied for the multigroup diffusion problems. The diffusion code, CITATION, is... more
It is shown that the Shanks sequence -transformation and the conventional extrapolation method are theoretically related. The -transformation method is then applied for the multigroup diffusion problems. The diffusion code, CITATION, is modified for this study and the computing time is compared for each iteration tactics. The Equipose method, in which only sing1e inner iteration for each energy group is carried for an outer iteration, has been known as the fastest iteration method. However, in the case of 3-group problems, the proposed method, in which the number of inner iteration for the fast and thermal group is 2 and 1 respectively, gives better convergency than the Equipose method by about 12%. The double extrapolation method results in faster computing time than the single extrapolation method without computing storage problem. It is, however, to note that this method is verified only for a two-group treatment.t.
Research Interests:
A finite element method is formulated for one-speed integral equation it or the neutron transport in a slab reactor. The formulation incorporates both the linear and the cubic Hermite interpolating polynomials and is used to compute the... more
A finite element method is formulated for one-speed integral equation it or the neutron transport in a slab reactor. The formulation incorporates both the linear and the cubic Hermite interpolating polynomials and is used to compute the approximate solutions for the slab criticality and Milne problem. The results are compared with the exact solutions available and then the effectiveness of the method is extensively discussed.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
The lattice dynamics of Cr, Mo, and W are formulated in terms of a simple shell model in which the transition metal ions in the crystals are treated as deformable ions. The model involves a total of seven parameters; two charge parameters... more
The lattice dynamics of Cr, Mo, and W are formulated in terms of a simple shell model in which the transition metal ions in the crystals are treated as deformable ions. The model involves a total of seven parameters; two charge parameters and five force constant parameters. The numerical values of the model parameters are determined by fitting to three elastic constants and the lattice vibrational frequencies measured by the neutron inelastic scattering experiments. Attempts are made to compute the phonon dispersion relations, the frequency distribution functions, and the lattice specific heats of three metals. The results are compared with experiments. It is found that the simple shell model can give a satisfactory account for the lattice vibrational characteristics of transition metals. The usefulness of the model is then discussed in comparison With other lattice dynamical models.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Korea imports about 97% of its energy resources due to a lack of available energy resources. In this status, the role of nuclear power in electricity generation is expected to become more important in future years. In particular, a fast... more
Korea imports about 97% of its energy resources due to a lack of available energy resources. In this status, the role of nuclear power in electricity generation is expected to become more important in future years. In particular, a fast reactor system is one of the most promising reactor types for electricity generation, because it can utilize efficiently uranium resources and reduce radioactive waste. Acknowledging the importance of a fast reactor in a future energy policy, the long-term advanced SFR development plan was authorized by KAEC in 2008 and updated in 2011 which will be carried out toward the construction of an advanced SFR prototype plant by 2028. Based upon the experiences gained during the development of the conceptual designs for KALIMER, KAERI recently developed advanced sodium-cooled fast reactor (SFR) design concepts of TRU burner that can better meet the generation IV technology goals. The current status of nuclear power and SFR design technology development prog...
Research Interests:
The creep properties for the Hastelloy-X alloy which is one of candidate alloys for a high temperature gas-cooled reactor are presented. The creep data was obtained with different stresses at 950oC, and a number of the creep data was... more
The creep properties for the Hastelloy-X alloy which is one of candidate alloys for a high temperature gas-cooled reactor are presented. The creep data was obtained with different stresses at 950oC, and a number of the creep data was collected through literature surveys. All of the creep data were combined together to obtain the creep constants and to predict a long-term creep life. In the Norton’s creep law and the Monkman-Grant relationship, the creep constants, A, n, m, and m’ were obtained. Creep master curves based on the Larson-Miller parameter were presented for the standard deviations of 1σ, 2σ and 3σ. Creep life at each temperature was predicted for a longer-time rupture above 105 hours. Failure probability was also estimated by a statistical process of all the creep rupture data.
Research Interests:
Research Interests:
A sensitivity simulation of neutron tomography was performed for the analysis of the spatial distribution of nuclear materials in the HANARO fuel rod. The internal distribution of the nuclear materials in the fuel rod is very important... more
A sensitivity simulation of neutron tomography was performed for the analysis of the spatial distribution of nuclear materials in the HANARO fuel rod. The internal distribution of the nuclear materials in the fuel rod is very important for the increase of the safety and economics of fuel burnup in the reactor. The neutron radiography facility installed at HANARO will be used for the spatial fuel analysis with a real-time image processing system. Monte Carlo simulation was performed to study the feasibility and sensitivity of the HANARO neutron beam for the spatial fuel assay and to find the optimum conditions for neutron detection. From the sensitivity simulation, the location of the nuclear materials in the rod was evident as expected.
Research Interests:
Research Interests:
Research Interests:
Subroutines to enable fast and accurate generation of water properties-enthalpy, specific volume, viscosity, thermal conductivity and saturation entropy-which are usually basic requirements for nuclear calculation of LWR, have been... more
Subroutines to enable fast and accurate generation of water properties-enthalpy, specific volume, viscosity, thermal conductivity and saturation entropy-which are usually basic requirements for nuclear calculation of LWR, have been developed. The sources of data were quoted from “ASME Steam Tables (1967)” and their Revision (1975). It is ensured that the obtained values from this routine fall within 0.2% difference compared with the reference data, in the ranges of temperature and pressure for LWR nuclear calculation.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT Monochromatic MeV-energy neutron source for secondary reaction was developed utilizing tritium embedded titanium (Ti-3H) thin film via 3H(p,n)3He reaction. We have measured the neutron energies and the energy spread by resonance... more
ABSTRACT Monochromatic MeV-energy neutron source for secondary reaction was developed utilizing tritium embedded titanium (Ti-3H) thin film via 3H(p,n)3He reaction. We have measured the neutron energies and the energy spread by resonance reactions of 12C(n,tot) and 28Si(n,tot). The available energy was within the range from 0.6 to 2.6 MeV. Energy spread was 1.6% at energy of 2.077 MeV. The flux in the beam direction was determined to be 3.76·107 n/s/sr by irradiating 197Au by about 2 MeV neutrons. This source was shown to be useful for measurements of nuclear data by measuring the total cross sections of neutrons on Fe and comparing these data to the data of ENDF-6.
Research Interests:
One of the key issues in developing a sulfur–iodine (SI) thermochemical hydrogen production technology is how to operate the SI process, including the start-up operation procedure. In order to effectively establish a start-up procedure,... more
One of the key issues in developing a sulfur–iodine (SI) thermochemical hydrogen production technology is how to operate the SI process, including the start-up operation procedure. In order to effectively establish a start-up procedure, it is necessary to develop a dynamic simulation code that can analyze the dynamic behavior of the SI process. Furthermore, a dynamic simulation is necessary for identifying the transient behaviors of the SI process by abnormal operation occurrences, which is a nuclear hydrogen process, coupled to a very high temperature gas-cooled reactor (VHTR) through an intermediate heat exchanger (IHX). In this paper, a VHTR-based SI process coupling system for a dynamic simulation code development is introduced. Component and integration modules for a dynamic simulation program including input/output graphical user interface (GUI) modules are also described, and the start-up dynamic behaviors of the SI process have been anticipated using the simulation code developed in this study. The GUI system of the dynamic simulation program, which has been developed using ChartFX and Spread 7.0, allows users to easily manage the I/O data generated from the dynamic simulation program of the SI process.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT The neutron total cross section of natural Ag and Sm has been measured in the energy region from 0.1 eV to 100 eV by the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator,... more
ABSTRACT The neutron total cross section of natural Ag and Sm has been measured in the energy region from 0.1 eV to 100 eV by the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and an 11 m long time-of-flight path. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm has been used as a neutron detector and metallic plates of Ag and Sm samples have been used for the neutron transmission measurement. The background level has been deterrnined by using notch-filters of Co, In, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and that from neutron capture, we have employed a neutron-gamma separation system based on their different pulse shapes. The present measurements are in general agreement with the previous ones and the evaluated data in ENDF/B-VI. The resonance parameters of Ag isotopes (107Ag and 109Ag) have been extracted from the transmission data by using the SAMMY code.
Research Interests:
The changes in the microhardness and Young’s modulus of the 2 MeV C+ ion–irradiated IG-110 isotropic nuclear graphite were evaluated by a dynamic ultra-microhardness test. Indentation depth and load dependency of the hardness and elastic... more
The changes in the microhardness and Young’s modulus of the 2 MeV C+ ion–irradiated IG-110 isotropic nuclear graphite were evaluated by a dynamic ultra-microhardness test. Indentation depth and load dependency of the hardness and elastic modulus were observed possibly due to the formation of a range. Both the hardness and Young’s modulus (E) – dpa curves have shown an incubation dose for about ı 0.3 mdpa. After the incubation dose, both the hardness and E showed a rapid increase with the dose. The doses that corresponds to these rapid increases in the hardness and E coincides with the dose that corresponds to the beginning of the irradiationinduced surface distortion, and the loss of the graphite crystallinity (amorphization).
Research Interests:
Research Interests:
Research Interests:
ABSTRACT Designing of a sulfur trioxide decomposer is one of the main technical challenges in the development of a nuclear hydrogen production system. Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer... more
ABSTRACT Designing of a sulfur trioxide decomposer is one of the main technical challenges in the development of a nuclear hydrogen production system. Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand the severe operating conditions. In this design, the hot gas side is equipped with printed circuit-type heat exchangers (PCHE), and the process gas side is equipped with plate fin-type heat exchangers (PFHE). In this study, the sensitivity analysis is performed to estimate the effects of the various factors on the thermal design of a sulfur trioxide decomposer for its performance test in a small-scale gas loop. The principal factors affecting the decomposer's thermal design are categorized into four groups: rate constants, geometrical parameters, heat transfer parameters, and operating conditions. Our results indicate that the rate constant of the catalyzed reaction and the decomposer retention time are the most important factors dictating the thermo-chemical behavior of the sulfur trioxide decomposer. The information obtained from this analysis will serve to guide the manufacture and operation of this laboratory-scale decomposer.
Research Interests:
Research Interests:
Research Interests:
... In the alkaline water electrolysis, the cells use aqueous solutions of KOH, NaOH or NaCl as the electrolyte. ... The HTES uses a combination of thermal energy and electricity to splitwater in an electrolyzer similar to a solid oxide... more
... In the alkaline water electrolysis, the cells use aqueous solutions of KOH, NaOH or NaCl as the electrolyte. ... The HTES uses a combination of thermal energy and electricity to splitwater in an electrolyzer similar to a solid oxide fuel cell (SOFC). ...
Research Interests: Engineering, Nuclear Engineering, Materials Science, Chemistry, Hydrogen, and 15 moreGAS TURBINE, Iodine, Hydrogen Energy, Hydrogen Production, High Temperature, Efficiency, Heat Recovery, CHEMICAL SCIENCES, Sulfur, Electrolysis, Thermal Efficiency, Thermodynamic Properties, High Temperature Electrolysis, Operating Temperature, and Electrolisis
ABSTRACT The neutron cross sections of 19 selected high-priority nuclei were evaluated in the fast energy region. The calculation was compared with the CSISRS experimental data and the ENDF files. Evaluation procedures included an... more
ABSTRACT The neutron cross sections of 19 selected high-priority nuclei were evaluated in the fast energy region. The calculation was compared with the CSISRS experimental data and the ENDF files. Evaluation procedures included an optical-model parameter search, followed by complete nuclear reaction model calculations with parameters validated against experimental data. A spherical and deformed optical model, MSC and MSD, pre-equilibrium exiton, and Hauser-Feshbach with a width fluctuation were used in the EMPIRE code. A considerable improvement was achieved for most of the nuclei cases. The results were merged with the resonance parameters (adopted in ENDF/B-VI.8). The final files were submitted to ENDF/B-VII for review.
Research Interests:
Research Interests:
ABSTRACT In an effort to develop a thermal-hydraulic (TH) safety analysis code for Gas-cooled Reactors (GCRs), the MARS code, which was primarily developed for TH analysis of water reactor systems, has been extended here for application... more
ABSTRACT In an effort to develop a thermal-hydraulic (TH) safety analysis code for Gas-cooled Reactors (GCRs), the MARS code, which was primarily developed for TH analysis of water reactor systems, has been extended here for application to GCRs. The modeling requirements of the system code were derived from a review of major processes and phenomena that are expected to occur during normal and accident conditions of GCRs. Models fur code improvement were then identified through a review of existing MARS code capability. Among these, the following priority models necessary fur the analysis of limiting high and low pressure conduction cooling events were evaluated and incorporated in MARS-GCR/V1 : 1) Helium (He) and Carbon Dioxide () as main system fluids, 2) gas convection heat transfer, 3) radiation heat transfer, and 4) contact heat transfer models. Each model has been assessed using various conceptual problems for code-to-code benchmarks and it was demonstrated that MARS-GCR/V1 is capable of capturing the relevant phenomena. This paper describes the models implemented in MARS-GCR/V1 and their verification and validation results.