[en] This study was performed to produce the experimental data required for design of LMR by installing the experimental facilities for the computer code verification experiments, and develop the elemental components which can be used in sodium facilities or in the LMR, accumulate the basic technology for the developments of these components through the experiment based on sodium. And this study was performed to assure the technology for the safety and the handling of sodium through the sodium safety experiment. The results of this study are to be used as the data for the verification of computer code, and the basic data for the design of KALIMER. The measuring technology and the data based on sodium are to be used for the development of elemental components and the design of experimental facility related to sodium.

[en] Growth of large-grain polycrystalline silicon has been demonstrated using silicide-mediated crystallization of amorphous silicon (a-Si) by a pulsed rapid thermal annealing (RTA). The Ni atoms in concentration of 4.6x10¹²/cm² on the a-Si surface were heated at 700 deg. C in the RTA system for 10 s, ten times with 60 s intervals between the heat pulses. The Ni atoms on a-Si aggregate together, forming NiSi₂ precipitates. The crystallization proceeds from the NiSi₂ nuclei until the neighboring crystallites collide and forms distinct grain boundaries. It was found that 3.6x10⁷ Ni atoms form a seed for metal induced crystallization and the grain size was 40 μm when the Ni density was 4.6x10¹²/cm² on the a-Si. The grain size increases with decreasing metal density on a-Si

[en] Laser ablation of surfaces normally produce high temperature plasmas that are difficult to control. By irradiating small particles in the gas phase, we can better control the size and concentration of the resulting particles when different materials are photofragmented. Here, we irradiate soot with 193 nm light from an ArF excimer laser. Irradiating the original agglomerated particles at fluences ranging from 0.07 to 0.26 J/cm² with repetition rates of 20 and 100 Hz produces a large number of small, unagglomerated particles, and a smaller number of spherical agglomerated particles. Mean particle diameters from 20 to 50 nm are produced from soot originally having a mean electric mobility diameter of 265nm. We use a non-dimensional parameter, called the photon/atom ratio (PAR), to aid in understanding the photofragmentation process. This parameter is the ratio of the number of photons striking the soot particles to the number of the carbon atoms contained in the soot particles, and is a better metric than the laser fluence for analyzing laser-particle interactions. These results suggest that UV photofragmentation can be effective in controlling particle size and morphology, and can be a useful diagnostic for studying elements of the laser ablation process

[en] The sliding wear behavior of the material of a steam generator in a nuclear power station (Inconel 600) was investigated at room temperature. Effects of the wear parameters such as material combination, sliding distance and contact stress were examined with various mating materials including 304 austenitic stainless steel, Inconel 600 and Al-Cu alloy 2011. In the prediction of the wear volume by Archard's wear equation, the standard error range was calculated to be ±4.04x10^-9 m³ and the reliability to be 71.9% for the combination of Inconel 600 and 304 stainless steel. The error range was considered to be relatively broad because the wear coefficient in Archard's equation was assumed to be a constant, regardless of the changes in the mechanical properties during the wear. In the present study, the sliding wear behavior turned out to be influenced by the material combination; the wear volume of 304 stainless steel did not linearly increase with the sliding distance, while that of other material combinations exhibited linear increases. Based on the experimental results, the wear coefficient was modified as a function of the sliding distance. The calculation with the modified wear equation showed that the error range narrowed down to ±2.60x10^-9 m³ and the reliability increased to 75.3%, compared to Archard's original equation

[en] The sodium is widely used as one of the coolants in the liquid metal reactor system since it has important safety features such as a long thermal response time, a large margin to coolant boiling, and operating in near atmospheric pressure, etc. The state-of-the-art on the flow and pressure measurement techniques in the piping system worldwide is investigated and reviewed to utilize it as a basis for developing a new technique applying for the high temperature sodium flow environment

[en] Two perforated plates are used to investigate local heat/mass transfer characteristics in an impingement/effusion cooling system. A naphthalene sublimation method is conducted to determine the local heat/mass transfer coefficients on the upward facing surface of the effusion plate. The two plates are placed in parallel position with gap distances of 1, 2, 4 and 6 times of effusion hole diameter. The effects of hole arrangements of the plates are studied for staggered, square, and hexagonal arrays. The experiments are conducted at Reynolds number of 10,000 based on the effusion hole diameter. The results show that the smaller hole size in the staggered array has the higher transfer coefficients on the stagnation region due to the formation of higher momentum flows through the impingement holes. In the square array, heat/mass transfer on the target plate is more uniform as the number of impingement holes increases. High and uniform heat/mass transfer coefficients are obtained in the hexagonal array

[en] Two Perforated Plates are used to investigate local heat/mass transfer characteristics in an impingement/diffusion cooling system. A naphthalene sublimation method is conducted to determine the local heat/mass transfer coefficients on the upward facing surface of the effusion plate. Two plates are placed in parallel position with gap distances of 1, 2, 4, and 6 times of effusion hole diameter. The effects of hole arrangements of the plates are studied for staggered ,square, and hexagonal arrays. The experiments are conducted at Reynolds number of 10,000 based on the effusion hole diameter. The results show that the smaller hole size in the staggered array has the higher momentum flows through the impingement holes. In the square array, heat/mass transfer coefficients are obtained for the hexagonal array

[en] Magnetic field has many effects on the hydraulic pressure drop of fluids with high electrical conductivity. The theoretical solution about MHD pressure drop is sought for the uniform current density model with simplified physical geometry. Using the MHD equation in the rectangular duct of the sodium liquid flow under a transverse magnetic field, the electrical potential is sought in terms of the duct geometry and the electrical parameters of the liquid metal and duct material. By the product of the induced current inside the liquid metal and transverse magnetic field, the pressure gradients is found as a function of the duct size and the electrical conductivity of the liquid metal. The theoretically predicted pressure drop is compared with experimental results on the change of flow velocity and magnetic flux density

[en] Sodium of liquid metals is superior to others in the aspect of nuclear or thermal-hydraulic character and it is industriously so abundant that it is widely used for the cooling material of liquid metal reactor. Sodium cooled fast reactor studying in KAERI adopts the decay heat removal system of a self developed safety rating. To prove the inherent design concept and its performance, it constructs Sodium integral effect TEST Loop for safety simulation and Assessment. Before the an efficiency test utilizing this large scaled facility is done, this research preferentially studied about the impurities such as oxygen and hydrogen included in sodium and about flow calibration, making use of small sized sodium loop of such a function. That is because the impurities included in liquid sodium makes safe drive of liquid metal reactor hard, especially the rate of oxygen corrosion fast and the rate of movement of carbon contents increase. Oxygen mainly creates sodium oxide in the response with sodium and it causes plugging not melted in sodium but deposited in cold spot so that the oxygen concentration in liquid sodium must be kept lowly. Thus the removal of impurity can low the concentration as simple as possible, using the device of cold trap so that it is considerably used. In driving of liquid sodium loop, oxygen is also permeated so that the oxygen concentration of sodium gets higher. In order to keep a watch on this, the concentration should be able to be measured periodically. A way to collect direct specimen in the measure of oxygen concentration is spent much time and has a problem that is easily oxidized in the process of collecting specimen. Thus most vastly utilized measure as more reliable thing is the plugging meter by plugging of orifice. To purify and measure we must know the first concentration of oxygen that is impurity. The Electronics Magnetic Flow used for the measure is designed and manufactured according to a pipe size. Therefore, it is demanded to test for calibration. This study present contents performed in respect to this

[en] The use of sodium as a coolant in a liquid metal reactor(LMR) has many advantages due to its thermal properties while a disadvantage that a major sodium spill and a pipe rupture of sodium coolant systems will usually result in a sodium fire. The rise of temperature and pressure, the release of aerosol in the buildings as a result of a sodium fire must be considered for the safety measures of a LMR. Subsequent effect of a sodium fire depends upon whether the sodium continues to leak from the pipe or not, whether the ventilation system is running, whether the inert gas injection system is provided, whether the sodium on the floor is drained into the smothering tank or not, whether the building is sealed or not, etc. Therefore, for the safety of a LMR, it is necessary to understand the characteristics of a sodium fire, resulting from various types of leakage. ASSCOPS(Analysis of Simultaneous Sodium Combustion in Pool and Spray) is the computer code for the analysis of the thermal consequences of a sodium leak and fire in a LMFR that has been developed by JAEA in Japan. Computer code includes two sodium combustion codes called SOFIRE II and SPRAY. SOFIRE II code has been developed to compute 1-cell and 2-cell pool fire cases by Atomics International(AI), and the SPRAY code has been developed to evaluate the consequences of a postulated sodium spray release from LMFR piping leak by Hanford Engineering Development Laboratory(HEDL) in USA. This study describes a preliminary analysis of sodium leak and fire accidents in the S/G building of KALIMER. Various phenomena of interest are the spray and pool burning, peak pressure, temperature change, the drain system into the smothering tank, ventilation characteristics at each cell with the safety venting system and nitrogen injection system