• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1547-1554
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• 2017

VESTA (Verification of Ex-vessel corium STAbilization) and VESTA-S (-small) test facilities were constructed at the Korea Atomic Energy Research Institute in 2010 to perform various corium melt experiments. Since then, several tests have been performed for the verification of an ex-vessel core catcher design for the EU-APR1400. Ablation tests of an impinging $ZrO_2$ melt jet on a sacrificial material were performed to investigate the ablation characteristics. $ZrO_2$ melt in an amount of 65-70 kg was discharged onto a sacrificial material through a well-designed nozzle, after which the ablation depths were measured. Interaction tests between the metallic melt and sacrificial material were performed to investigate the interaction kinetics of the sacrificial material. Two types of melt were used: one is a metallic corium melt with Fe 46%, U 31%, Zr 16%, and Cr 7% (maximum possible content of U and Zr for C-40), and the other is a stainless steel (SUS304) melt. Metallic melt in an amount of 1.5-2.0 kg was delivered onto the sacrificial material, and the ablation depths were measured. Penetration tube failure tests were performed for an APR1400 equipped with 61 in-core instrumentation penetration nozzles and extended tubes at the reactor lower vessel. $ZrO_2$ melt was generated in a melting crucible and delivered down into an interaction crucible where the test specimen is installed. To evaluate the tube ejection mechanism, temperature distributions of the reactor bottom head and in-core instrumentation penetration were measured by a series of thermocouples embedded along the specimen. In addition, lower vessel failure tests for the Fukushima Daiichi nuclear power plant are being performed. As a first step, the configuration of the molten core in the plant was investigated by a melting and solidification experiment. Approximately 5 kg of a mixture, whose composition in terms of weight is $UO_2$ 60%, Zr 10%, $ZrO_2$ 15%, SUS304 14%, and $B_4C$ 1%, was melted in a cold crucible using an induction heating technique.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1639-1645
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• 1991

Because of the important role LD converters play in the production of high quality steel, various dynamic models have been attempted in the past by many researchers not only to understand the complex chemical reactions that take place in the converter process but also to assist the converter operation itself using computers. And yet no single dynamic model was found to be completely satisfactory because of the complexity involved with the process. The process indeed involves dynamic energy and mass balances at high temperatures accompanied by complex chemical reactions and transport phenomena in the molten state. In the present study, a mathematical model describing the dynamic behavior of LD converter process has been developed. The dynamic model describes the time behavior of the temperature and the concentrations of chemical species in the hot metal bath and slag. The analysis was greatly facilitated by dividing the entire process into three zones according to the physical boundaries and reaction mechanisms. These three zones were hot metal (zone 1), slag (zone 2) and emulsion (zone 3) zones. The removal rate of Si, C, Mn and P and the rate of Fe oxidation in the hot metal bath, and the change of composition in the slag were obtained as functions of time, operating conditions and kinetic parameters. The temperature behavior in the metal bath and the slag was also obtained by considering the heat transfer between the mixing and the slag zones and the heat generated from chemical reactions involving oxygen blowing. To identify the unknown parameters in the equations and simulate the dynamic model, Hooke and Jeeves parttern search and Runge-Kutta integration algorithm were used. By testing and fitting the model with the data obtained from the operation of POSCO #2 steelmaking plant, the dynamic model was able to predict the characteristics of the main components in the LD converter. It was possible to predict the optimum CO gas recovery by computer simulation

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.468-472
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• 2005

In order to prevent adhering of molten glass on a mold wall, the wall is swabbed with lubricant oil before forming. However, the swabbing process can be removed from the entire processes of the glass forming if the mold wall is made of a porous sintered material. The purpose of the present study is to manufacture a sintered material(having a sintered density of $85{\~}90\%$)which is the most appropriate into. plane material for a glass mold. For the research, SUS310L-based coarse powder (${\~}150{\mu}m$) and SUS420J2-based fine powder ($40{\~}50{\mu}m$) were used for the compact materials, and effects of compaction pressure and sintering condition(atmosphere, temperature) were investigated. The results obtained were as fellows. (1) By means of solid phase sintering, a desired sintering density could not be achieved in any case when using a 310L-based powder having a large particle size. (2) When sintering green compacts(compaction pressure of $2ton/cm^2$) in a commercial vacuum furnace(at $1300^{\circ}C$ for 2 hours), the sintered compacts had densities of $6.2g/cm^3(79\%)$ for 310L + 0.03$\%$B, $6.6g/cm^3 (86\%)$ for 420J2, $7.3g/cm^3(95\%)$ for 420J2+(0.03)$\%$B, and $7.6g/cm^3(99\%)$ for 420j2+(0.06)$\%$B, respectively. As a result, it is regarded that sintered compacts having a desired porosity may be achieved by vacuum sintering the 420J2-based powder (low pressure compaction) and the 310L+0.03$\%$B-based powder (high pressure compaction).

• Korean Journal of Heritage: History & Science
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• v.43 no.3
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• pp.102-121
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• 2010

Three bronze bells excavated from the Hoeamsa temple site were investigated for their microstructures and chemical compositions in an effort to understand the technology applied in fabrication, which may represent the related industry established in the early Joseon period. The result shows that the bells were cast from alloys of approximately 85% copper-8% tin-7% lead. The chemical analysis for ten trace elements shows that they were all kept below 0.3 weight %, suggesting that the alloys were made of relatively well-refined copper, tin and lead. The presence of sulfur and iron indicates that chalcopyrite or chalcocite may have been used in the smelting of copper. Evidence has been found that the bells were cast by pouring the liquid metal from the top of the sand molds that were set up in an upright position. No additional treatments, thermal or mechanical, other than a little grinding were applied upon the completion of casting. After the shaping process, a balancing plate was attached to the top of the bell using a steel connection ring. The connection assembly was then fixed to the main body by using molten bronze as a solder. The surface inscription was found carved using different techniques. The differences in the order of strokes and the calligraphic style indicate that the carving was carried out by more than one master. In the absence of documentary evidence on past bronze technology, the present bronze bells with known chronology, provenance and the main agent of production, prove to be a rare and valuable archaeological material for the understanding of the related technology in use in the early Joseon period.

• Resources Recycling
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• v.33 no.2
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• pp.54-61
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• 2024

When steel contaminated with Pb, produced by the decay of natural radionuclides, is remelted, Pb distributes among the metal, slag, and gas phases. In this study, 5 wt%Pb was added to Fe and melted with CaO-SiO₂-Al₂O₃-MgO slag to investigate Pb's distribution in the metal/slag/gas. As slag basicity ((wt%CaO)/(wt%SiO₂)) increased, Pb solubility in Fe slightly increased, while Pb in the slag tended to decrease. Consequently, the slag/metal distribution ratio of Pb decreased with increasing basicity. Thermodynamic calculations revealed that the slag/Fe phase distribution ratio of Pb remained very low irrespective of the activity coefficient of PbO in the slag, consistent with the experimental results. The calculated evaporation rate of Pb in Fe-Pb was approximately 22 times that of Fe; hence, most of the Pb evaporated into the gas phase.