• Journal of Korean Society of Water and Wastewater
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• v.36 no.5
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• pp.249-260
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• 2022

The effect of permanganate oxidation was investigated as water treatment strategy with a focus on comparing the reaction characteristics of NaOCl and sodium permanganate (NaMnO₄) in algae (Monoraphidium sp., Micractinium inermum, Microcystis aeruginosa)-contained water. Flow cytometry explained that chlorine exposure easily damaged algae cells. Damaged algae cells release intracellular organic matter, which increases the concentration of organic matter in the water, which is higher than by NaMnO₄. The oxidation reaction resulted in the release of toxin (microcystin-LR, MC-LR) in water, and the reaction of algal organic matter with NaOCl resulted in trihalomethanes (THMs) concentration increase. The oxidation results by NaMnO₄ significantly improved the concentration reduction of THMs and MC-LR. Therefore, this study suggests that NaMnO₄ is effective as a pre-oxidant for reducing algae damage and byproducts in water treatment process.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.271-277
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• 2015

The present paper discusses about noble idea on various reactions including hydrides, hydrogen peroxide and nano-sized metal powders, which do not emit toxic materials as well as carbon dioxide. Here in this paper, the very first-ever concept that heat energy can be generated from the direct reaction between sodium borohydride and hydrogen peroxide is presented. Sodium hydride as fuel can supply hydrogen reacting with oxygen provided by the decomposition of hydrogen peroxide solution. Solid sodium borohydride can be resolved in water and treated as liquid solution for the easy handling and the practical usage although its solid powder can be directly mixed with hydrogen peroxide for the higher reactivity. The thermodynamic analysis was conducted to estimate adiabatic reaction temperatures from these materials. The preliminary experiment on the reactions conducted using sodium borohydride powder and hydrogen peroxide water solution revealed that the self-propagating reaction can occur and that its reactivity increases with an increase of hydrogen peroxide concentration.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.66-82
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• 1999

The national long-term R&D program, updated in 1997, requires Korea Atomic Energy Research Institute(KAERI) to complete by the year 2006 the basic design of Korea Advanced Liquid Metal Reactor(KALIMER), along with supporting R&D work, with the capability of resolving the issue of spent fuel storage as well as with significantly enhanced safety. KALIMER is a 150 MWe pool-type sodium cooled prototype reactor that uses metallic fuel. The conceptual design is currently under way to establish a self-consistent design meeting a set of major safety design requirements for accident prevention. Some of the current emphasis includes those for inherent and passive means of negative reactivity insertion and decay heat removal, high shutdown reliability, prevention of and protection from sodium chemical reaction, and high seismic margin, among others. All of these requirements affect the reactor design significantly and involve extensive supporting R&D programs. This paper summarizes some of the results of conceptual engineering and design analyses performed for the safety of HAMMER in the area of inherent safety, passive decay heat removal, sodium water reaction, and seismic isolation.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1023-1029
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• 1998

Small water leak experiment was carried out for the 5Cr-1Mo steel specimen in sodium atmosphere. Perfect re-open time for the leak path of a specimen, by micro leak, was 129 minutes, and its size observed about 2 mm diameter at sodium side. The halos phenomena appeared around of leak spot before the leak path has re-opened, and the size of halos observed was different from the real re-open size of a specimen. Also, the corrosion of a specimen initiated from sodium side, but it did not occur at steam side. In AES analysis, the segregation phenomena of Cr in the specimen was found much more than those of other elements. And also, the sodium compounds formed by sodium-water reaction and deposited onto the leak site of specimen were observed by EPMA analysis and SEM photograph. It is postulated that the corrosion products could be precipitated to form mixed Na Fe Cr compounds.

• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.411-415
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• 1973

The reaction between cyanide ion and triphenyl methane dyes is subject to marked catalysis by cationic micelles of cetyltrimethyl ammonium bromide(CTABr) and retarded by anionic micelles of sodium lauryl sulfate(NaLS). Added salts, anions inhibit the catalysis by CTABr, and cations, especially $Zn^{++},\;Cd^{++}$ decrease the retardation of the reaction rates in the presence of NaLS. The kinetic effects of the ionic micelles are much larger in water than in ethanol-water, methanol-water, propanol-water and acetone-water, but strange solvent effects, acceleration the reaction rates, was found in the reaction with malachite green in water-methanol system.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.257-264
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• 2024

The sodium cooled fast reactor (SFR) is one of the Gen-IV reactors with the most operating experience accumulated. Although the technology level is the most mature among the Gen-IV reactors, there is still a safety problem that has not been solved, which is the sodium-water reaction. Since sodium and water are separated only by a heat transfer tube with a thickness of only a few mm, there is inherently a risk of a sodium-water reaction (SWR) accident in the SFR. In this study, it is attempted to quantitatively evaluate the resistance of SWR accidents by replacing the shell and tube steam generator with printed circuit steam generator (PCSG) as a method to mitigate the SWR accident. To do this, a CATS-S (Compact Accident Tolerance Steam Generator-SWR) facility was designed and built. And for the quantitative evaluation of accident resistance, a methodology for measuring the impingement wastage rate was established. As a result of this research, the impingement wastage rate caused by SWR generated in a PCSG was measured first time. It was confirmed that the impingement wastage phenomenon was suppressed in the PCSG, and the accident resistance was higher than that of the SWR through comparison with the experimental results performed in the existing shell and tube steam generator. In conclusion, a PCSG is more resistant to impingement wastage as a result of the SWR accident than existing shell and tube steam generators, and it is estimated that a PCSG can mitigate SWR accidents, an inherent problem of SFR.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.662-668
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• 2015

A suspension of titanium nanoparticles (Ti NPs) in liquid sodium (Na) has been proposed as a method to mitigate the violent sodium-water reaction (SWR). The interparticle potential between Ti NPs in liquid Na may play a significant role in the agglomeration of NPs on the reaction surface and in the bulk liquid Na, since the potential contributes to a reduction in the long-term dispersion stability. For the effective control of the SWR with NPs, a physical understanding of the molecular dynamics of NPs in liquid Na is key. Therefore in this study, the nonretarded Van der Waals model and the solvation potential model are employed to analyze the interparticle potential. The ab initio calculation reveals that a strong repulsive force driven by the solvation potential exceeds the interparticle attraction and predicts the agglomeration energy required for two 10-nm Ti NPs to be $4{\times}10^{-17}J$. The collision theory suggests that Ti NPs can be effective suppressors of the SWR due to the high energy barrier that prevents significant agglomeration of Ti NPs in quiescent liquid Na.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.170-179
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• 2017

We investigated design requirements of feed water drain and hydrogen vent systems for the sodium-water reaction pressure relief system (SWRPRS) of the prototype generation IV sodium cooled fast reactor (PGSFR). We evaluated the areas of the gas vent pipe of the water dump tank and the length of the water drain pipe of the steam generator to rapid drain of the water steam inside the steam generator for the normal and refueling operations, respectively. We also calculated the diameter of the gas vent pipe of the sodium dump tank which met its design pressure.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.674-679
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• 1998

Small water leak experiment was carried out in liquid sodium atmosphere using a specimen of ferrite steel, which will be expected to be a material of the heat transfer tube of liquid metal fast breeder reactor. Self-plugging phenomena of leak path could be explained by the products of reaction and corrosion by sodium-water reaction. Also, re-opening mechanism of self-plugged path could be explained by the thermal transient and vibration of heat transfer tube. As a result, perfect re-opening time of self-plugged leak path was observed to be 129 minutes after water leak initiation. Re-opening shape of a specimen was appeared with double layer of circular type, and re-opening size of this specimen surface was about 2 mm diameter on sodium side.

• Journal of the Korean Ceramic Society
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• v.45 no.1
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• pp.54-59
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• 2008

Hydrated sodium silicate with 25 wt% water contents was synthesized by hydrothermal reaction using anhydrous sodium silicate. The hydrated sodium silicate was expanded at $370^{\circ}C$ for 30 min. and then pulverized, classified (- 200 mesh) and press-formed. The samples were heat treated at $400{\sim}900^{\circ}C$ for 30 min. in order to study the expansion characteristics depending on heat treatment temperature. A porous body with closed pore was formed above $600^{\circ}C$. The volume expansion ratio and the pore size were increased and the specific gravity was decreased with increasing heat treatment temperature. However, the volume expansion ratio was decreased and the specific gravity was increased above $850^{\circ}C$ due to the softening of the sodium silicate.