[en] Target systems for spallation neutrons are designed to enhance production and neutronic efficiencies as well as to investigate a target cooling system. Lead and tungsten are chosen for target materials. Three target systems (solid cylinder, solid disc array, disc-array in cylindrical shell) for applications to a subcritical fast reactor are introduced to investigate neutronic characteristics of each target geometry. By making use of LCS simulation code, neutron production and leakage rates are calculated for each target design. The cost effective neutron yields turns out to be ≅27 n/s at 1.3 GeV for solid lead target, and ≅24 n/s at 1.5 GeV for solid tungsten target, per an incident proton. Single proton from 1 GeV accelerator deposits total heat of 588 MeV in solid lead target and 600 MeV in solid tungsten target. As far as spallation neutron yields and heat removal system design are concerned, lead target system has advantage of the tungsten target. By adjusting size of solid lead target, the optimal radius and height of the target are found to be ≅11 cm, and ≅50 cm, respectively. Energy spectra of neutron fluxes of the tungsten target system shows much better performance than those of lead target in the energy range of lower than 1 MeV. Relation of the size of target and axial distributions of neutron fluxes is discussed in this paper. Also, we present a method to reduce leakages through top and bottom surfaces by adjusting a gap distance of disc-array type target system. Our neutronic results obtained from lead target can also be applied to liquid lead target system except for heat removal mechanisms

[en] We discuss the theories in the generation and detection of laser-ultrasonics and present the results obtained from the numerical calculations based on the theories. We carry out the computation of the spatial and temporal distributions of the temperature inside the material. Calculating the displacement of the surface at the epicenter, we make discussions on the characteristics of the ultrasonic wave propagation in the thermoelastic and ablation regions. The speed and the surface motion of the material element are investigated from the solution of the Rayleigh equation. We present the results obtained from the numerical computations based on the theories. The Rayleigh waves generated by the irradiation of the pulsed laser beam in the thermoelastic region and the ablation region are discussed. Also the discussions on the heat wave propagation caused by irradiations of the ultra-short laser pulses are included in the appendix

[en] Dynamics of Free-electron lasers(FEL) is investigated on the basis of the pendulum equations in the one-dimensional formulation. The phase-space evolution and the bunching coefficients of the electrons, which enable one to find the evolution of the radiation field, are briefly reviewed. Describing the computational procedures for solving the FEL pendulum equations numerically, we discuss the electron dynamics and the evolutions of the radiation field in the various gain regimes and the saturation regimes. Also we carried out numerical studies on the inhomogeneous broadening effects due to the energy spread and emittance of an electron beam

[en] A stiffness in a dynamical system is numerically studied to investigate a sensitivity of a reactor to the delayed neutron spectra with the Doppler feedback effect. To test numerical procedure, we adopted a case of a reactivity accident in a point reactor model. We found that the stiffness is sensitive to a reactivity insertion rate and the delayed neutron spectra in the Doppler feedback phase. Our numerical results show that global reactor characteristics are not very sensitive to the delayed neutron spectra even though their instantaneous ones are sensitive. We present the time evolution of each precursor group explicitly

[en] A 2D finite-element numerical simulation has been developed to investigate the generation of ultrasonic waves in a homogeneous isotropic elastic slab under a line-focused laser irradiation. Discussing the physical processes involved in the thermoelastic phenomena, we describe a model for the pulsed laser generation of ultrasound in a metal slab. Addressing an analytic method, on the basis of an integral transform technique, for obtaining the solutions of the elastodynamic equation, we outline a finite element method for a numerical simulation of an ultrasonic wave propagation. We present the numerical results for the displacements and the stresses generated by a line-focused laser pulse on the surface of a stainless steel slab

[en] A thermal wave solution of a hyperbolic heat conduction equation in a thin film is developed on the basis of the Green's function formalism. Numerical computations are carried out to investigate the temperature response and the propagation of the thermal wave inside a thin film due to a heat pulse generated by ultra-short laser pulses with various laser pulse durations and thickness of the film

[en] We discuss the theories in the generation and detection of laser-ultrasonics and present the results obtained from the numerical calculations based on the theories. We carry out the computation of the spatial and temporal distributions of the temperature inside the material. Calculating the displacement of the surface at the epicenter, we make discussions on the characteristics of the ultrasonic wave propagation in the thermoelastic and ablation regions

[en] We discuss the generation of the surface waves from the mode conversion occurred at the boundary due to the reflection processes of the ultrasonic waves. The speed and the surface motion of the material element are investigated from the solution of the Rayleigh equation. We present the results obtained from the numerical computations based on the theories. The Rayleigh waves generated by the irradiation of the pulsed laser beam in the thermoelastic region and the ablation region are discussed

[en] The preliminary design of the advanced quantum beam source based on a superconducting electron accelerator is presented. The advanced quantum beams include: high power free electron lasers, monochromatic X-rays and γ-rays, high-power medium-energy electrons, high-flux pulsed neutrons, and high-flux monochromatic slow positron beam. The AQBS system is being re-designed, assuming that the SPS superconducting RF cavities used for LEP at CERN will revived as a main accelerator of the AQBS system at KAERI, after the decommissioning of LEP at the end of 2000. Technical issues of using the SPS superconducting RF cavities for the AQBS project are discussed in this report. The advanced quantum beams will be used for advanced researches in science and industries

[en] Korea Rare Isotope Accelerator (KoRIA) is a heavy ion accelerator which is being developed mainly for producing RI beams to study nuclear physics and astrophysics. One of the important application areas of KoRIA is the nuclear data. Various types of stable beams can be used for measurements related to the reactions induced by charged particles. In addition, proton and deuteron beams among charged particles can be used to produce neutrons by irradiating appropriate target materials. Those neutrons are used to measure the cross sections and other nuclear data related to neutron induced reactions. In this paper, we introduce the conceptual design of a neutron TOF facility which can produce fast neutrons for neutron cross section measurements