• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1677-1688
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• 2020

In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2005년도 봄 학술발표회지 제14권(제1호)
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• pp.267-271
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• 2005

This experiment was carried out at 450"C, which is relatively lower than the temperature for supercritical water oxidation (600-650$^{\circ}C$). In this experiment, the decomposition rates of various incombustible organic substances were very high. In addition, it was confirmed that hetero atoms existed in organic compounds and chlorine was neutralized by sodium(salt formation).However, to raise the decomposition rate, relatively large amount of sodium nitrate(3-4 times the equivalent weight) was required. When complete oxidation is intended as in the case with PCB, the amount of oxidizer and decomposition cost is important. But when vaporization reduction is required as in the case with nuclear wastes, the amount of radioactive wastes increases instead. But as can be seen in the result of XRD measurement, unreacted sodium nitrate remained unchanged. If oxidation reaction of organic substance simply depends on collision frequency, unreacted sodium nitrate can be recovered and reused, then oxidation equivalent weight would be sufficient. In the gas generated, toxic gas was not found. As the supercritical water medium has high reactivity, it is difficult to generate relatively low energy level SO$_{X}$, and NO$_{X}$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.84-84
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• 2007

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3557-3558
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• 2011

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.139.1-139
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• 2002

• 한국토양비료학회지
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• 제31권4호
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• pp.334-341
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• 1998

Sodium hydroxide concentrations were adjusted to 2.0, 2.5, 3.0 and 3.5M by dissolution in seawater. The fly ash was hydrothermally reacted with sodium hydroxide solutions (1:8, W:V) at $100^{\circ}C$ under the closed system. X-ray diffractogram proved that Na-P1 type zeolite was produced from bituminous coal fly ash. It is different from the X-ray of artificial zeolite produced by using sodium hydroxide solution dissolving in distilled water. Solid sieve structure was developed well by hydrothermal reaction with the ash and 3.0M sodium hydroxide. However chinks were observed in the structure of the product by 3.5M sodium hydroxide. CEC of the artificial zeolite was $244.5cmol^+\;kg^{-1}$ at 2.0M, 259.8 at 3.0M, 263.4 at 3.0M and 179.8 at 3.5M after 24 hours hydrothermal reaction; Artificial zeolite having high CEC, above $244.5cmol^+\;kg^{-1}$ could produce by using lower concentration of NaOH prepared in seawater than other production methods.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.105-106
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• 2005

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1528-1539
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• 2023

Since the leakage of sodium in an SFR (sodium-cooled fast reactor) causes an explosion upon reaction with air and water, sodium leakages represent an important safety issue. In this study, a novel technique for improving the reliability of sodium leakage detection applying DDVR (dynamic data validation and reconciliation) is proposed and verified to resolve this technical issue. DDVR is an approach that aims to improve the accuracy of a target system in a dynamic state by minimizing random errors, such as from the uncertainty of instruments and the surrounding environment, and by eliminating gross errors, such as instrument failure, miscalibration, or aging, using the spatial redundancy of measurements in a physical model and the reliability information of the instruments. DDVR also makes it possible to estimate the state of unmeasured points. To validate this approach for supporting sodium leakage detection, this study applies experimental data from a sodium leakage detection experiment performed by the Korea Atomic Energy Research Institute. The validation results show that the reliability of sodium leakage detection is improved by cooperation between DDVR and hardware measurements. Based on these findings, technology integrating software and hardware approaches is suggested to improve the reliability of sodium leakage detection by presenting the expected true state of the system.

• 상하수도학회지
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• 제29권4호
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• pp.481-491
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• 2015

The aim of this study was to evaluate the chemical quenching system for residual ozone and to determine the operating condition for the quenching system. Hydrogen peroxide ($H_2O_2$) and sodium thiosulfate ($Na_2S_2O_3$) were investigated as quenching reagents for ozone removal, and the tendency of each chemical was notably different. In the case of $H_2O_2$, the degradation rate of ozone was increased as the concentration of $H_2O_2$ increase, and temperature and pH value have a significant effect on the degradation rate of ozone. On the other hand, the degradation rate of ozone was not affected by the concentration of $Na_2S_2O_3$, temperature and pH value, due to the high reactivity between the ${S_2O_3}^{2-}$ and ozone. This study evaluates the decomposition mechanism of ozone by $H_2O_2$ and $Na_2S_2O_3$ with consideration for the water quality and reaction time. Furthermore, the removal test for the quenching reagents, which can be remained after reaction with ozone, was conducted by GAC process.

• 한국재료학회지
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• 제24권5호
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• pp.271-276
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• 2014

Silica nano-powder (SNP) is an inorganic material able to provide high-performance in various fields because of its multiple functions. Methods used to synthesize high purity SNP, include crushing silica minerals, vapor reaction of silica chloride, and a sol-gel process using TEOS and sodium silicate solution. The sol-gel process is the cheapest method for synthesis of SNP, and was used in this study. First, we investigated the shape and the size of the silica-powder particles in relation to the variation of HCl and sodium silicate concentrations. After drying, the shape of nano-silica powder differed in relation to variations in the HCl concentration. As the pH of the solution increased, so did the density of crosslinking. Initially, there was NaCl in the SNP. To increase its purity, we adopted a washing process that included centrifugation and filtration. After washing, the last of the NaCl was removed using DI water, leaving only amorphous silica powder. The purity of nano-silica powder synthesized using sodium silicate was over 99.6%.