• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.53-55
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• 1986

The $trans{\rightarrow}cis$ photoisomerization and fluorescence of trans-1,2-bispyrazylethylene were investigated in various conditions. The quantum yields of the $trans{\rightarrow}cis$ photoisomerization and the fluorescence intensity of trans-1,2-bispyrazylethylene decrease on going from neutral to acidic or basic solutions. The quantum yields of photoisomerization, however, are little affected by changing the concentration of salt while the fluorescence intensity increases as the concentration of salt increases. pH and salt effects on the energy levels of $^1(n,\;{\pi}^*)\;and\;^1({\pi},\; {\pi}^*)$ states lead to opposing changes in photoisomerization and fluorescence quantum yields. The heavy atom effect on the fluorescence of 1,2-bispyrazylethylene was also investigated.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1390-1397
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• 2019

SiC coating and SiC/glassy carbon composite coating were prepared on IG-110 nuclear graphite (Toyo Tanso Co., Ltd., Japan) to strengthen its inertness to molten fluoride salt used in molten salt reactor (MSR). Two kinds of modified graphite were obtained and correspondingly named as IG-110-1 and IG-110-2, which referred to modified IG-110 with a single SiC coating and a SiC/glassy carbon composite coating, respectively. Both structure and property of modified graphite were carefully researched and contrasted with virgin IG-110. Results indicated that modified graphite presented better comprehensive properties such as more compact structure and higher resistance to molten salt infiltration. With the protection of coatings, the infiltration amounts of fluoride salt into modified graphite were much less than that into virgin IG-110 at the same circumstance. Especially, the infiltration amount of fluoride salt into IG-110-2 under 5 atm was merely 0.26 wt%, which was much less than that into virgin IG-110 under 1.5 atm (13.5 wt%) and the critical index proposed for nuclear graphite used in MSR (0.5 wt%). The SiC/glassy carbon composite coating gave rise to highest resistance to molten salt infiltration into IG-110-2, and thus demonstrated it could be a promising protective coating for nuclear graphite used in MSR.

• Journal of Energy Engineering
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• v.17 no.1
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• pp.23-30
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• 2008

The neutron kinetic analysis methods for the molten-salt reactors are quite different from those for conventional solid-fuel reactors, which do not take into account the flowing-fuel-induced neutronics effects. Therefore, for dynamics and safety analyses of the molten-salt reactor systems, the conventional kinetics codes would not be appropriate to accurately predict its transient behaviors. A point-kinetics with flowing- fuel model has been used to assess the fluid-fuel reactor system safety, but recognized as not to be sufficient to simulate spatial distributions of delayed-neutron precursors and neutron populations during transients for given detail reactor models. In order to meet this requirement, AMBIKIND, a 2-group, 2-dimensional neutron kinetics code suitable for the molten-salt reactor systems was developed. This paper explains the code's theoretical and numerical descriptions and, as a part of its verification, includes some simulation results of MSRE stability experiments. Even though the present reactor model does not include the recirculation effect of the fuel-salt through the reactor system, the AMBIKIN2D code should be able to predict the power and phase shift at various power levels and reactivity insertions with better accuracy.

• BMB Reports
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• v.38 no.4
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• pp.481-485
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• 2005

The response of Spirulina (Arthrospira) platensis to high salt stress was investigated by incubating the cells in light of moderate intensity in the presence of 0.8 M NaCl. NaCl caused a decrease in photosystem II (PSII) mediated oxygen evolution activity and increase in photosystem I (PSI) activity and the amount of P700. Similarly maximal efficiency of PSII (Fv/Fm) and variable fluorescence (Fv/Fo) were also declined in salt-stressed cells. Western blot analysis reveal that the inhibition in PSII activity is due to a 40% loss of a thylakoid membrane protein, known as D1, which is located in PSII reaction center. NaCl treatment of cells also resulted in the alterations of other thylakoid membrane proteins: most prominently, a dramatic diminishment of the 47-kDa chlorophyll protein (CP) and 94-kDa protein, and accumulation of a 17-kDa protein band were observed in SDS-PAGE. The changes in 47-kDa and 94-kDa proteins lead to the decreased energy transfer from light harvesting antenna to PSII, which was accompanied by alterations in the chlorophyll fluorescence emission spectra of whole cells and isolated thylakoids. Therefore we conclude that salt stress has various effects on photosynthetic electron transport activities due to the marked alterations in the composition of thylakoid membrane proteins.

• Analytical Science and Technology
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• v.13 no.6
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• pp.759-765
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• 2000

A study on the separation of Zr metal from $LiF-BeF_2-ZrF_4$ (67-27-6 mol%) molten salt was carried out using electrowinning. The decomposition potentials of the $LiF-BeF_2$ (72-28 mol%) and the $LiF-BeF_2-ZrF_4$ (67-27-6 mol%) molten salts were measured to be -1.55 and -1.35 volt, respectively. The Zr separation voltage from the salt were found to be in a range of -1.4 -1.5 volt. As increasing applied current, the deposition of molten salt on a cathode increases but the current efficiency decreases. In addition, the deposition and current efficiency decreases with increasing temperature.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.281-282
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• 2005

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.235-242
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• 1998

Aiming at one of decisive alternatives for long term aspect of nuclear power concerns, an integral and closed nuclear system, AMBIDEXTER (Advanced Molten-salt Break-even Inherently-safe Dual-mission Experimental and TEst Reactor) concept is under development. The AMBIDEXTER complex essentially comprises two mutually independent loops of the radiation/material transport and the heat/energy conversion, centered at the integrated reactor assembly, which enables one to utilize maximum benefits of nuclear energy under minimum risks of nuclear radiation. And it provides precious radioisotopes and radiation sources from its waste stream. Also the reactor operates at very low level of fission products inventory throughout its lifetime. The nuclear and thermalhydraulic characteristics of the molten TH/$^{233}$ U fuel salt extend the capability of the self-sustaining AMBIDEXTER fuel cycle to enhance resource security and safeguard transparency. The reactor system is consisted of a single component module of the core, heat exchangers and recirculation pumps with neither pipe connections nor active valves in between, which will significantly improve inherent features of nuclear safety. States of the core technologies associated with designing and developing the AMBIDEXTER concept are mostly available in commercialized form and thus demonstration of integral aspects of the concept should be the prime area in future R＆D programs.

• The Korean Journal of Ecology
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• v.8 no.3
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• pp.153-161
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• 1985

Energy flow through the trophic levels was studied at a salt marsh ecosystem distinguished into low and high marsh. Gross primary productions of Suaedeto-Salicornietum and Artemisieto-Limonietum at low marsh were 8, 299 and 13, 154kca/$m^2$/yr, and those of Calama-grostetum and Sonchuso-Setaetum at high marsh were 17, 899 and 15, 177kca/$m^2$/yr, respectively. Efficiencies of solar energy utilization of plants were 1.7 and 2.6% at the former, and were 3.6 and 3.2% at the latter. Of gross productions, net primary productions were 3, 977 and 5, 280kca/m2/yr at low marsh and were 6, 354 and 5, 329kca/$m^2$/yr at high marsh, and the remainder, 52~67%, was consumed by respiration of plants. A small amount (0.03~0.04%) of the net primary production was flowed through grazing food chain and most amout was transferred into dead parts. Of dead parts, 40% was accuulated as litter and the rest was decomposed into detritus. In the detritus food chain, a little energy was utilized by detritus feeder, and a major by microorganism. The amounts of energy flowed through grazing and detritus feeders at high marsh were much more than those at low marsh, but tertary production as spider was Vice versa.

• Carbon letters
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• v.15 no.1
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• pp.38-44
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• 2014

This paper reports the effect of adding reduced graphene oxide (RGO) as a conductive material to the composition of an electrode for capacitive deionization (CDI), a process to remove salt from water using ionic adsorption and desorption driven by external applied voltage. RGO can be synthesized in an inexpensive way by the reduction and exfoliation of GO, and removing the oxygen-containing groups and recovering a conjugated structure. GO powder can be obtained from the modification of Hummers method and reduced into RGO using a thermal method. The physical and electrochemical characteristics of RGO material were evaluated and its desalination performance was tested with a CDI unit cell with a potentiostat and conductivity meter, by varying the applied voltage and feed rate of the salt solution. The performance of RGO was compared to graphite as a conductive material in a CDI electrode. The result showed RGO can increase the capacitance, reduce the equivalent series resistance, and improve the electrosorption capacity of CDI electrode.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.77-84
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• 2010

Reduction of oxides has been investigated for the volume reduction and recycling of the spent oxide fuel from commercial nuclear power plants. Various oxide reduction methods were proposed and KAERI (Korea Atomic Energy Research Institute) is currently developing an electrochemical reduction process using a LiCl-$Li_2O$ molten salt as a reaction medium. The electrochemical reduction process, the front end of the pyroprocessing, can connect the PWR (Pressurized Water Reactor) oxide fuel cycle to a metal fuel cycle of the sodium cooled fast reactor. This paper summarizes KAERI efforts on the development, improvement, and scale-up of the oxide reduction process.