• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2002.11a
• /
• pp.76.2-77
• /
• 2002

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.14 no.3
• /
• pp.211-221
• /
• 2016

Waste salt generated from a pyro-processing for the recovery of uranium and transuranic elements has high volatility at vitrification temperature and low compatibility in conventional waste glasses. For this reason, KAERI (Korea Atomic Energy Research Institute) suggested a new method to de-chlorinate waste salt by using an inorganic composite named SAP ($SiO_2-Al_2O_3-P_2O_5$). In this study, the de-chlorination behavior of waste salt and the microstructure of consolidated form were examined by adding $B_2O_3$ and $Fe_2O_3$ to the original SAP composition. De-chlorination behavior of metal chloride waste was slightly changed with given compositions, compared with that of original SAP. In the consolidated forms, the phase separation between Si-rich phase and P-rich phase decreases with the amount of $Al_2O_3$ or $B_2O_3$ as a connecting agent between Si and P-rich phase. The results of PCT (Product Consistency Test) indicated that the leach-resistance of consolidated forms out of reference composition was lowered, even though the leach-resistance was higher than that of EA (Environmental Assessment) glass. From these results, it could be inferred that the change in the content of Al or B in U-SAP affected the microstructure and leach-resistance of consolidated form. Further studies related with correlation between composition and characteristics of wasteform are required for a better understanding.

• Journal of the Korean Ceramic Society
• /
• v.40 no.10
• /
• pp.936-942
• /
• 2003

In order to develop glass formulations for vitrifying Low-and Intermediate-Level radioactive Wastes (LILW) from nuclear power plants of Korea Hydro & Nuclear Power (KHNP) Co., Ltd., promising glass formulations were selected based on glass property model predictions for viscosity, electrical conductivity and leach resistance. Laboratory measurements were conducted to verify the model predictions. Based on the results, the models for electrical conductivity, US DOE 7-day Product Consistency Test (PCT) elemental release, and pH of PCT leachate are accurate for the LILW glass formulations. However, the model for viscosity was able to provide only qualitative results. A leachate conductivity test was conducted on several samples to estimate glass leach resistance. Test results from the leachate conductivity test were useful for comparison before PCT elemental release results were available. A glass formulation K11A meets all the KHNP glass property constraints, and use of this glass formulation on the pilot scale is recommended. Glass formulations K12A, K12B, and K12E meet nearly all of the processing constraints and may be suitable for additional testing. Based on the comparison between the measured and predicted glass properties, existing glass property models may be used to assist with the LILW glass formulation development.

• Applied Chemistry for Engineering
• /
• v.2 no.3
• /
• pp.289-299
• /
• 1991

In order to obtain glasses appropriate to the thick film copper conductors, nine glasses based on both lead borosilicate and leadless borosilicate systems were made and the applicabilities of them were examined in conjunction with the requirements for thick film copper conductors. As the results, it was found that all the glasses are fitted to provide suitable sheet resistance, solderability and solder leach resistance to thick film copper conductors. However, it was turned out that only the lead borosilicate based glasses worked for getting usable aged adhesion strength of copper thick film to the alumina substrate, while copper conductor films made from the other glasses had poor aged adhesion strengths. Particularly cuprous oxide added lead borosilicate glass was considered as one of the most favorable glasses for manufacturing thick film copper conductors.

• Applied Chemistry for Engineering
• /
• v.2 no.3
• /
• pp.193-198
• /
• 1991

Thick film copper conductors are of considerable interest in thick film industries because of both the potential cost saving compared to the noble metal conductors and the favorable properties in electrical conductivity, solderability, solder leach resistance and wire bondability, However, formation of the excellent copper thick film is a lot complicated due to easily oxidizing property of copper at high temperature. In order to get favorable thick film copper conductor, hybrid microcircuit industry utilizes majorly three kinds of firing atmosphere, such as nitrogen atmosphere, reactive atmosphere and air atmosphere. The processes and the three atmospheres for firing thick film copper conductor were extensively reviewed in this article.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2003.04a
• /
• pp.1-19
• /
• 2003

The electronic market thrust for many hybrid circuit manufacturers is changing because commercial market segments such as telecommunications, automotive and consumer electronics have increased the demand world wide for environmentally friendly thick film products. This, in turn, places a stronger emphasis on the material suppliers within the circuit fabrication industry to provide toxin free products with equal or higher performance than traditional technology. A new group of silver based thick film conductors, which are totally free of such toxins as cadmium, nickel and Bead have been developed to meet new environmental requirements. Traditional thick film products and newly developed toxin free compositions will be compared and data will be presented. To evaluate their performance, both groups of conductors were tested for solder acceptance, leach resistance and aged adhesion with standard lead-containing solder and higher temperature lead-free solder.

• Computers and Concrete
• /
• v.31 no.4
• /
• pp.315-325
• /
• 2023

Calcium leaching is one of the main deterioration factors in concrete structures contact with water, such as dams, water treatment structures, and radioactive waste structures. It causes a porous microstructure and may be coupled with various harmful factors resulting in mechanical degradation of concrete. Several numerical modeling studies focused on the calcium leaching depth prediction. However, these required a lot of cost and time for many experiments and analyses. This study presents an artificial neural network (ANN) approach to predict the leaching depth quickly and accurately. Totally 132 experimental data are collected for model training and validation. An optimal ANN model was proposed by ANN topology. Results indicate that the model can be applied to estimate the calcium leaching depth, showing the determination coefficient of 0.91. It might be used as a simulation tool for engineering problems focused on durability.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.8 no.2
• /
• pp.99-105
• /
• 2010

This paper investigated the characteristics of wasteform containing a spent zeolite used as a separating agent of FPs for recycling LiCl waste which would be generated from pyrochemical process of spent PWR fuel. In this study, a conventional borosilicate and Ca-rich glass were used as a consolidating agent for spent zeolite and it's mixing ratio was changed in the range, $25{\sim}35wt%$. The leach rates of Cs and Sr had about $0.1{\sim}0.01g/m^2day$ and $0.001{\sim}0.0001g/m^2day$, respectively. The leach resistance of Cs increased with amount of SAP and it showed about 10 times higher in the Ca-rich glass wasteform than in the conventional borosilciate glass wasteform. The compressive strength of wasteform was affected with the amount of glass. Thermal expansion rate of containing 30wt% glass has relatively lower than others. Also, the melting temperature was little changed in given mixing ratio of glass.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.3
• /
• pp.171-177
• /
• 2007

This study suggested a new method to stabilize molten salt wastes generated from the pyre-process for the spent fuel treatment. Using conventional sol-gel process, $SiO_2-Al_2O_3-P_2O_5$ (SAP) inorganic material that is reactive to metal chlorides were prepared. In this paper, the reactivity of SAP with the metal chlorides at $650{\sim}850$, the thermal stability of reaction products and their leach-resistance under the PCT-A test method were investigated. Alkali metal chlorides were converted into metal aluminosilicate($LixAlxSi1-_xO_{2-x}$) and metal phosphate($Li_3PO_4\;and\;Cs_2AlP_3O_{10}$) While alkali earth and rare earth chlorides were changed into only metal phosphates ($Sr_5(PO_4)_3Cl\;and\;CePO_4$). The conversion rate was about $96{\sim}99%$ at a salt waste/SAP weight ratio of 0.5 and a weight loss up to $1100^{\circ}C$ measured by thermogravimetric analysis were below 1wt%. The leach rates of Cs and Sr under the PCT-A test condition were about $10^{-2}g/m^2\;day\;and\;10^{-4}g/m^2\;day$. From these results, it could be concluded that SAP can be considered as an effective stabilizer for metal chlorides and the method using SAP will give a chance to reduce the volume of salt wasteform for the final disposal through further researches.

• Journal of Applied Biological Chemistry
• /
• v.57 no.3
• /
• pp.189-196
• /
• 2014

In Korea, over 4,700 animal carcass disposal sites were installed until 2011 due to the outbreak of foot and mouth disease. Due to the putrefaction of buried animals, the leachate containing veterinary antibiotics may release into surrounding environments. Antibiotic residues in the environment cause the formation of antibiotic resistance bacteria threatening human and ecosystem health. This study reports the concentrations of five antibiotics, including tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC), sulfamethazine (SMZ), and sulfamethoxazole (SMX), in soils from animal carcass disposal site and adjacent agricultural field. Concentrations of antibiotics at animal carcass disposal sites (TC: $144.26-350.73{\mu}g/kg$, SMZ: $17.72-44.94{\mu}g/kg$) were higher than those at agricultural field (TC: $134.16-320.73{\mu}g/kg$, SMZ: $6.48-8.85{\mu}g/kg$) whereas the concentrations of CTC, OTC, and SMX were below detection limit in both sites. Results showed that the antibiotics in animal carcass site might leach to the soil and possibly contaminating the groundwater. Future studies will focus on the transfer of antibiotics residues into food crops.