• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1687-1707
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• 2023

This paper presents a molten salt reactor (MSR) design parameter sensitivity study using a nodal dynamic modelling methodology with explicitly modified point kinetics equation and Mann's model for heat transfer. Six parameters that can impact MSR safety are evaluated. A MATLAB-Simulink model inspired by Thorcon's 550MWth MSR is used for parameter evaluations. A safety envelope was formed to encapsulate power, maximum and minimum temperature, and temperature-induced reactivity feedback. The parameters are perturbed by ±30%. The parameters were then ranked by their subsequent impact on the considered safety envelope, which ranks acceptable parameter uncertainty. The model is openly available on GitHub.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.268-277
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• 2004

process (ACP), electrochemical properties of high heat-generating alkali and alkali earth oxides in molten salt were measured and the behavior of those elements were analyzed. The reduction potentials of Cs, Sr, and Ba in a molten LiCl-$Li_2O$ system were more cathodic than that of Li and closely located one another. Thus, it is expected that the alkali and alkali earth would not hinder the reaction mechanism which is via lithium reduction. Alkali and alkali earth metals are likely to recycle into molten salt when the process is operated beyond metal reduction potentials and the effect of electric current on the mass transport is also determined by measuring the metal concentrations in the molten salt phase at different current conditions.

• Korean Journal of Materials Research
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• v.16 no.9
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• pp.557-563
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• 2006

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. So, it is essential to choose the optimum material for the process equipment handling molten salt. In this study, corrosion behavior of Inconel 713LC, MA 754, X-750 and 718 in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere was investigated at $650^{\circ}C$ for $72{\sim}216$ hours. Inconel 713LC alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of Inconel 713LC were $Cr_2O_3,\;NiCr_2O_4$ and NiO, and those of Inconel MA 754 were $Cr_2O_3\;and\;Li_2Ni_8O_{10}$ while $Cr_2O_3,\;NiFe_2O_4\;and\;CrNbO_4$ were produced from Inconel 718. Also, corrosion products of Inconel X-750 were found to be $Cr_2O_3,\;NiFe_2O_4\;and\;(Cr,Nb,Ti)O_2$. Inconel 713LC showed local corrosion behavior and Inconel MA 754, 718, X-750 showed uniform corrosion behavior.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.556-563
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• 1999

The corrosion behavior of heat-resistant alloys, More 1 and Super 22H in molten salts of LiCl and $LiCl-Li_2$O was investigated in the temperature range of $650~850^{\circ}C$. In a molten salt of LiCl, a dense protective oxide scale of $LiCrO_2$ was formed, following growth of oxide scale with parabolic kinetics. But in a mixed molten salt of LiCl, a dense protective oxide scale of $LiCrO_2$ was formed, following growth of oxide scale with parabolic kinetics. But in a mixed molten salt of $LiCl-Li_2$O, a porous non-protective scale of Li\ulcorner(Cr, Ni, Fe)\ulcornerO$_2$was formed, following growth of oxide scale with linear kinetics. The corrosion rate increased slowly with the increase of temperature up to $750^{\circ}C$, but above $750^{\circ}C$ rapid increase in corrosion rate observed. The corrosion behavior of Super 22H alloy was similar to that of More 1 alloy, but Super 22H showed higher corrosion resistance than More 1.

• Korean Journal of Metals and Materials
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• v.46 no.9
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• pp.577-584
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• 2008

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. So, it is essential to choose the optimum material for the process equipment handling molten salt. In this study, corrosion behavior of Inconel 713LC, Inconel MA 754, Nimonic 80A and Nimonic 90 in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere was investigated at $650^{\circ}C$ for 72~216 hrs. Inconel 713LC alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of Inconel 713LC were $Cr_2O_3$, $NiCr_2O_4$ and NiO, and those of Inconel MA 754 were $Cr_2O_3$ and $Li_2Ni_8O_{10}$ while $Cr_2O_3$, $LiFeO_2$, $(Cr,Ti)_2O_3$ and $Li_2Ni_8O_{10}$ were produced from Nimonic 80A. Also, corrosion products of Nimonic 90 were found to be $Cr_2O_3$, $(Cr,Ti)_2O_3$, $LiAlO_2$ and $CoCr_2O_4$. Inconel 713LC showed local corrosion behavior and Inconel MA 754, Nimonic 80A, Nimonic 90 showed uniform corrosion behavior.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4431-4440
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• 2022

An advanced nuclear reactor based on molten salts including a molten salt reactor and pyroprocessing needs a sensitive monitoring system suitable for operation in harsh environments with limited access. Multi-element detection is challenging with the conventional technologies that are compatible with the in-situ operation; hence laser-induced breakdown spectroscopy (LIBS) has been investigated as a potential alternative. However, limited precision is a chronic problem with LIBS. We increased the precision of LIBS under high temperature by protecting optics using a gas protective layer and correcting for shotto-shot variance and lens-to-sample distance using a laser-induced acoustic signal. This study investigates cerium as a surrogate for uranium and corrosion products for simulating corrosive environments in LiCl-KCl. While the un-corrected limit of detection (LOD) range is 425-513 ppm, the acoustic-corrected LOD range is 360-397 ppm. The typical cerium concentrations in pyroprocessing are about two orders of magnitude higher than the LOD found in this study. A LIBS monitoring system that adopts these methods could have a significant impact on the ability to monitor and provide early detection of the transient behavior of salt composition in advanced molten salt-based nuclear reactors.

• Journal of the Korean institute of surface engineering
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• v.31 no.4
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• pp.223-230
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• 1998

The separator for a molten carbonate fuel cell(MCFC) is mode of stainless steel and known to the suscepibility to corrosion due to environments of high temperature molten carbonte electrolyte. Considering the sensitization of stainless steel in the temperature range of 425~$815^{\circ}C$, the separator is expected to be sensitized so that the interganular corrosion (IGC) occurs during the cell operation at about $650^{\circ}C$. In this study, EPR(electrochemical potentiokinetic reactivation) technique was examined by relating some elements(mainly C and Cr) to the degree of sensitization of austenitic stainless steels in the molten carbonate salt at $650^{\circ}C$and the possible mechanism of intergranular corrosion was analyzed.

• Nuclear Engineering and Technology
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• v.36 no.5
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• pp.415-419
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• 2004

The electrode potential characteristics of a YSZ based membrane metal oxide electrode have been studied in molten LiCL at $700^{\circ}C$ by the potentiometric method. The electrode exhibited a good potential response to log[$O^2$] and data reproducibility. The calibration plot (potential vs. log[$O^2$] was found to be linear, obeying the Nernst equation. The electrode potential showed a good reversibility corresponding to increase/decrease of the oxide ion present in the molten LiCl. The physical and chemical durability appeared to be sound after several repeated uses, resulting in reproducible results. However, "the proposed electrode" failed when metallic Li was present in the melt.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.762-769
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• 2024

The TMSR-SF0 simulator is an integral effect thermal-hydraulic experimental system for the development of thorium molten salt reactor (TMSR) program in China. The simulator has two heat transport loops with liquid FLiNaK. In literature, the 95% level confidence uncertainties of the thermophysical properties of FLiNaK are recommended, and the uncertainties of density, heat capacity, thermal conductivity and viscosity are ±2%, ±10, ±10% and ±10% respectively. In order to investigate the effects of thermophysical properties uncertainties on the molten salt heat transport system, the uncertainty and sensitivity analysis of the heat transfer characteristics of the simulator system are carried out on a RELAP5 model. The uncertainties of thermophysical properties are incorporated in simulation model and the Monte Carlo sampling method is used to propagate the input uncertainties through the model. The simulation results indicate that the uncertainty propagated to core outlet temperature is about ±10 ℃ with a confidence level of 95% in a steady-state operation condition. The result should be noted in the design, operation and code validation of molten salt reactor. In addition, more experimental data is necessary for quantifying the uncertainty of thermophysical properties of molten salts.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1184-1189
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• 2018

Pyroprocessing uses various molten salts during electrochemical unit processes. Reaction products after the electrochemical processes must contain a significant amount of residual salts to be separated. Vacuum distillation is a common method to separate the residual salts; however, its high operation temperature may cause side reactions. In this study, a simple rotation technique using centrifugal force was suggested to separate the residual salts from the reaction products at relatively low temperature compared to the distillation technique. When a reaction product container with porous wall rotates inside a vessel heated above the melting point of the residual salt, the residual salt in the liquid phase is separated through centrifugal force. It was shown that the $LiNO_3-Al_2O_3$ mixture can be separated by this technique to leave solid $Al_2O_3$ inside the container, with a separation efficiency of 99.4%.