• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.1
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• pp.57-65
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• 2005

This study suggested a new method for the solidification of molten salt waste generated from the electro-metallurgical process in the spent fuel treatment. Using binary material system, sodium silicate and phosphoric acid, metal chlorides were converted into metal phosphate in the micro-reaction module formed by SiO$_{2} particles. The volatile element in the reaction module would little vaporized below 1100$^{circ}$C After the gel product was mixed with borosilicate glass powder and thermally treated at 1000$^{circ}$C, li exists as Li$_{3}$PO$_4$ separated from glass phase and, Cs and Sr would be incorporated into an amorphous phase from XRD analysis. In case of the addition of ZrCl$_{4}$ to the binary system, the gel products were transformed into NZP structure considered as an prospective ceramic waste form after heat-treatment above 700 $^{circ}$C. From these results, the gel-route pretreatment can be considered as an effective approach to the solidincation of molten salt waste by the confirmed process or waste form and this also would be an alternative method on the ANL method using zeolites in USA by the confirmation of its chemical durability as an future work.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.595-602
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• 2005

In order to purify diethylene glycol as main impurity included in p-dioxanone, SLE (solid-liquid equilibria) and mixture density on two components system of p-dioxanone and diethylene glycol were measured and a layered melt crystallization with seed has been applied. The SLE of p-dioxanone and diethylene glycol were a simple eutectic system and the temperature and PDX concentration at eutectic point were 0.08 and 246 K, respectively. Densities of their binary mixtures were well fitted by the best correlation equation, ${\rho}_l=0.405+1.361x+0.002T-0.004xT$. In the melt crystallization, the growth rate (G) was proportional to the 1.5th power of the subcooling degree. The effective distribution coefficient ($K_{eff}$) as the degree of impurity removal was observed to increase with increasing the growth rate and initial p-dioxanone concentration. And also, $K_{eff}$ was correlated with Z function using Wintermantel's model such as $K_{eef}=-0.0604+6.392{\times}Z$. Finally, PDX purity through the optimization of this process can be obtained over 99%.

• Analytical Science and Technology
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• v.13 no.2
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• pp.158-165
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• 2000

The purity of gypsum and quantitation of impurities of flue gas gypsum will not only play an important role in deciding of the optimal condition during a trial run of FGD (flue gas desulfurization), but also can be utilized in quality control of gypsum. The purity of gypsum can be determined from combined water, sulfur trioxide and calcium concentration. We found that the thermal analysis by TGA (thermogravimetric analysis) was the most accurate and convenient method to determine the purity of gypsum. This method will be done in a hour and the results were reproducible. On the other hand, the best way of the analysis of impurities in gypsum was fusion method using $LiBO_2$ as a fusion agent. We also determined the amount of $CO_2$ gas to analyze magnesium carbonate and calcium carbonate contents. The analyses of combined water by TGA, fusion method followed by ICP-AES (inductively coupled plasmaatomic emission spectroscopy) and determination of $CO_2$ amount can lead to more accurate and convenient method for gypsum analysis.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.4
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• pp.247-254
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• 2012

Vitrification technology has been widely applied as one of effective processing methods for wastes generated in nuclear power plants. The advantage of vitrifying for low- and intermediate-level radioactive wastes has a large volume reduction and good durability for the final products. Recently, a filter using on HVAC(Heating Ventilating & Air Conditioning System) is composed with media (glass fiber) and separator (aluminum film) has been studied the proper treatment technology for meeting the waste disposal requirement. Present paper is a feasibility study for the filter vitrification that developing of the glass compositions for filter melting and melting test for physicochemical characteristic evaluation. The aluminum metal of film type is preparing with 0.5 cm size for proper mixing with glass frit, glass fiber is also preparing with 1 cm size within crucible. The glass compositions should be developed considering molten glass are related with wastes reduction. Glass compositions obtained from developing on glass formulation are mainly composed of $SiO_2$ and $B_2O_3$ for aluminum metal. A variety of factors obtained from the glass formulation and melting test are reviewed, which is feeding rate and glass characteristics of final products such as durability for implementing the wastes disposal requirement.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.4
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• pp.229-236
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• 2012

A molten salt technology using $Li_2O$-LiCl has been extensively investigated to recover uranium metal from spent fuels in the field of nuclear energy. In the reduction process, it is an important point to maintain the concentration of $Li_2O$. $ZrO_2$ is inevitably contained in the spent fuels because Zr is one of the main components of fuel rod hulls. Therefore, the fate of $ZrO_2$ in $Li_2O$-LiCl molten salt has been investigated. It was found that $Li_2ZrO_3$ and $Li_4ZrO_4$ were formed chemically and electrochemically and they were not reduced to Zr. The recycling of $Li_2O$ is the key mechanism ruling the total reaction in the electrolytic reduction process. However, $ZrO_2$ will have a role as a $Li_2O$ sink.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.127-137
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• 2019

Zr electrorefining is demonstrated herein using Zirlo tubes in a chloride-fluoride mixed molten salt in the presence of $AlF_3$. Cyclic voltammetry reveals a monotonic shift in the onset of metal reduction kinetics towards positive potential and an increase in intensity of the additional peaks associated with Zr-Al alloy formation with increasing $AlF_3$ concentration. Unlike the galvanostatic deposition mode, a radial plate-type Zr growth is evident at the top surface of the salt during Zr electrorefining at a constant potential of -1.2 V. The diameter of the plate-type Zr deposit gradually increases with increasing $AlF_3$ concentration. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses for the plate-type Zr deposit show that trace amount of Al is incorporated as Zr-Al alloys with different chemical compositions between the top and bottom surface of the deposit. Addition of $AlF_3$ is effective in lowering the residual salt content in the deposit and in improving the current efficiency for Zr recovery.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.258-267
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• 1993

A mathematical model has been developed to describe heat transfer phenomena in a PCM (phase change material) module for development of an energy recovery system. The PCM module, melting point of which is around 1673 K, consists of silicon(96.8%), aluminium(2.7%) and marginal amounts of impurities such as Ca, Fe and Ti. The module is covered by a capsule that consists of SiC(58%) and graphite(42%). Physical properties that are required for model predictions were cited from the references. The apparent capacity method and the postiterative method wert used in the mathematical model to describe the phase changing mechanism. Temperature and velocity of fluid are the major variables in the model calculation. For the gas temperature of 1773 K that simulates real operating conditions, the prediction shows that PCM is rapidly melted to axial direction. However, for the gas temperature of 3000 K that is higher than the real conditions, PCM is melted rapidly to the radial direction. The gas velocity has no influence on the melting phenomena of the PCM except when the gas velocity is relatively low. At the low gas velocity asymmetry of the temperature profiles in PCM is obtained.

• Journal of Radiation Protection and Research
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• v.4 no.1
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• pp.14-20
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• 1979

For accurate and easily shielding irregular shaped organ, its minimized penumbra region and a low melting point alloy 'Lead Y' and synchronizing instrument have been developed. The 'Lead Y' is the quaternary eutectic alloy and it is composed of Lead 30.0% Tin 11.5% Bismuth 48 5% Cadmium 10.0% The density of its at $22^{\circ}C$ is $9.8g/cm^3$ and the melting temperature has $40^{\circ}C\;to\;68^{\circ}C$. The thickness of 'Lead Y' for perfect shielding of Co-60 gamma ray and LINAC 10MeV x-ray is 6cm and 7cm respectively. The 'Lead Y' shielding block is casted directly on the styrofoam from which is cut with hot wire of synchronizer device. The special features and advantages of the Lead Y shielding block could be summarized as follows; 1. The shielding block for radiotherapy is rapidly processed only with boiling water and styrofoam. 2. It is not injure one's health and not danger of a fire, because of not generating of any metals vapor and evil smelling. 3. It is very effective to minimize secondary penumbra for the protection of healthy tissue from unnecessary ionizing radiation regardless of the magnification source to skin distance. 4. The HVL of the Lead Y is 1.2cm for Co-60 gamma ray and it's shielding effect is almost same as the pure lead block. 5. The hardness of Lead Y is 1.5 times higher than lead block. 6. It's reavailability is higher than lead block and then one block of Lead Y is reavailable about 30 to 40 times. 7. It is usefull for shielding of x-ray, gamma ray, beta-ray, electron and neutron radiation. 8. The materials for Lead Y are easy to acquire with reasonable price and tractable.

• Resources Recycling
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• v.17 no.4
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• pp.57-65
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• 2008

The behavior of Na-A type zeolite formed in hydrothermal synthesis of melting slag from municipal incineration ash has been investigated with varying synthesis time and $SiO_2/Al_2O_3$ ratio. Sodium silicate and sodium aluminate feed was found to initially form nuclei of Na-A type zeolite in the behavioral study of the reaction products with different synthesis times. As the synthesis time increased, the nuclei have grown to Na-A type zeolite crystals by reacting with $SiO_2$ and $Al_2O_3$ dissolved from the melting slag. The hydrothermal synthesis was completed in 10 hr in the $SiO_2/Al_2O_3$ ratio of 1.38 and after that time, the Na-A type zeolite formed was dissolved and transformed into hydroxysodalite. Only Na-A type zeolite was formed in the $SiO_2/Al_2O_3$ ratio ranging 0.80 to 1.96, whereas Na-P type zeolite as well as Na-A type was formed in the $SiO_2/Al2O_3$ ratio of 2.54.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.33-39
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• 2010

The electrolytic reduction of a spent oxide fuel involves a liberation of the oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the processing equipment that handles the high molten salt. In this study, hot corrosion studies were performed on bare as well as coated superalloy specimens after exposure to lithium molten salt at $675^{\circ}C$ for 216 h under an oxidizing atmosphere. The IN713LC superalloy specimens were sprayed with an aluminized NiCrAlY bond coat and then with an $Y_2O_3$ top coat. The bare superalloy reveals an obvious weight loss due to spalling of the scale by the rapid scale growth and thermal stress. The chemical and thermal stability of the top coat has been found to be beneficial for increasing to the corrosion resistance of the structural materials for handling high temperature lithium molten salts.