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박환서,김인태,김환영,김준형,Park, Hwan-Seo,Kim, In-Tae,Kim, Hwan-Young,Kim, Joon-Hyung 한국방사성폐기물학회 2007 방사성폐기물학회지 Vol.5 No.3
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.
박환서,김인태,김환영,유승곤,김준형,Park Hwan Seo,Kim In Tae,Kim Hwan Young,Ryu Seung Kon,Kim Joon Hyung 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.1
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.
화상처리를 이용한 유연성디스크 가공 평면구간 측정에 관한 연구
노대호,박환서,이홍국,신관수,유송민,Roh, Dae-Ho,Park, Hwan-Seo,Lee, Hong-Guk,Shin, Kwan-Soo,Yoo, Song-Min 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.5
The goal of this study is to simplify the measurement process of the flat zone length produced by a flexible disk grinding system for the process automation. The image of workpiece in the grinding process is obtained, and the cutting speed and the feeding speed are controlled carefully to maximize the flat zone length. The gradient, the inflection point and the length of the line in the image are calculated, and the length is also measured by using a projector. Processing conditions and inversely proportional to flat zone length was changing. The flat zone length is estimated by Neural network algorithm considering the process conditions with the estimated error range as 0.06~3.61%, the Neural network algorithm for the grinding process estimation is found to be useful for building the process automation database.
안수나,박환서,조인학,김인태,조용준,Ahn, Soo-Na,Park, Hwan-Seo,Cho, In-Hak,Kim, In-Tae,Cho, Yong-Zun 한국방사성폐기물학회 2012 방사성폐기물학회지 Vol.10 No.1
금속염화물계 방사성 폐기물은 전해공정으로 이루어진 파이로프로세싱공정의 주요한 방사성 폐기물이다. 이와 같은 폐기물은 탄산염이나 질산염과 달리 고온에서 분해되지 않고 바로 휘발되며, 기존의 규산계 유리와 상용성이 낮아 처리가 쉽지 않다. 본 연구팀은 금속염화물계 폐기물을 고화처리하는 방법으로 탈염화처리법을 채택하였다. 본 연구에서는 그 후속적인 연구로서, 탈염화물질로 제안된 SAP ($SiO_2-Al_2O_3-P_2O_5$)의 조성을 변화시켜 LiCl-KCl과의 반응성을 향상시키고 고화공정을 단순화시키고자 하였다. 기본물질계에 $Fe_2O_3$를 첨가할 경우 무게반응비 SAP/Salt를 3에서 2.25로 낮출수 있으며, Fe가 Al을 치환하는 몰분율이 0.1이상이 될 경우에는 오히려 반응성이 점진적으로 감소하는 것으로 확인되었다. 또한 M-SAP에 $B_2O_3$를 첨가할 경우에는 유리매질을 사용하지 않고 monolithic form을 제조할 수 있었다. 침출 시험결과 U-SAP 1071이 가장 높은 내구성을 보여주었으며, 1 g의 금속폐기물을 처리시 약 3~4 g의 고화체가 발생되며, 이는 기존의 고화처리법보다 약 $\frac{1}{3}{\sim}\frac{1}{4}$배정도 최종처분부피가 감소되는 효과를 얻을 수 있다. 이상의 실험결과로부터, 기존의 유리고화공정으로 처리가 어려운 휘발성 금속염화물계 폐기물을 단 하나의 물질을 이용하여 처리할 수 있음을 확인하였으며, 이러한 처리방법은 고화처리시 발생되는 부피를 최소화활 수 있는 대안적인 고화처리방법이 될 것으로 판단된다. Metal chloride waste is generated as a main waste streams in a series of electrolytic processes of a pyrochemical process. Different from carbonate or nitrate salt, metal chloride is not decomposed into oxide and chlorine but it is just vaporized. Also, it has low compatibility with conventional silicate glasses. Our research group adapted the dechlorination approach for the immobilization of waste salt. In this study, the composition of SAP ($SiO_2-Al_2O_3-P_2O_5$) was adjusted to enhance the reactivity and to simplify the solidification process as a subsequent research. The addition of $Fe_2O_3$ into the basic SAP decreased the SAP/Salt ratio in weight from 3 for SAP 1071 to 2.25 for M-SAP( Fe=0.1). The experimental results indicated that the addition of $Fe_2O_3$ increased the reactivity of M-SAP with LiCl-KCl but the reactivity gradually decreased above Fe=0.1. Also, introducing $B_2O_3$ into M-SAP requires no glass binder for the consolidation of reaction products. U-SAP ($SiO_2-Al_2O_3-Fe_2O_3-P_2O_5-B_2O_3$) could effectively dechlorinate the LiCl-KCl waste and its reaction product could be consolidated as a monolithic form without a glass binder. The leaching test result indicated that U-SAP 1071 was more durable than other SAPs wasteform. By using U-SAP, 1 g of waste salt could generated 3~4 g of wasteform for final disposal. The final volume would be about 3~4 times lower than the glass-bonded sodalite. From these results, it could be concluded that the dechlorination approach using U-SAP would be one of prospective methods to manage the volatile waste salt.
조인학,박환서,안수나,김인태,조용준,Cho, In-Hak,Park, Hwan-Seo,Ahn, Soo-Na,Kim, In-Tae,Cho, Yong-Zun 한국방사성폐기물학회 2012 방사성폐기물학회지 Vol.10 No.1
The metal chloride wastes from a pyrochemical process to recover uranium and transuranic elements has been considered as a problematic waste difficult to apply to a conventional solidification method due to the high volatility and low compatibility with silicate glass. In this study, a dechlorination approach to treat LiCl-KCl waste for final disposal was adapted. In this study, a $SiO_2-Al_2O_3-P_2O_5$ (SAP) inorganic composite as a dechlorination agent was prepared by a conventional sol-gel process. By using a series of SAPs, the dechlorination behavior and consolidation of reaction products were investigated. Different from LiCl waste, the dechlorination reaction occurred mainly at two temperature ranges. The thermogravimetric test indicated that the first reaction range was about $400^{\circ}C$ for LiCl and the second was about $700^{\circ}C$ for KCl. The SAP 1071 (Si/Al/P=1/0.75/1 in molar) was found to be the most favorable SAP as a dechlorination agent under given conditions. The consolidation test revealed that the bulk shape and the densification of consolidated forms depended on the SAP/Salt ratios. The leaching test by PCT-A method was performed to evaluate the durability of consolidated forms. This study provided the basic information on the dechlorination approach. Based on the experimental results, the dechlorination method using a $SiO_2-Al_2O_3-P_2O_5$ (SAP) could be considered as one of alternatives for the immobilization of waste salt. 사용후 핵연료내 우라늄 및 초우란원소를 회수하는 파이로프로세싱 공정에서 배출되는 금속염화물계 방사성 폐기물은 높은 휘발특성과 붕규산계 유리와의 낮은 상용성으로 인해 고화처리가 쉽지 않은 폐기물이다. 이를 위해, 본 연구에서는 고화처리의 한 방법으로 탈염화 반응을 통한 고화체제조 개념을 채택하였다. 솔젤법을 이용하여 탈염화물질, $SiO_2-Al_2O_3-P_2O_5$ (SAP)을 합성하였으며 이를 이용하여 탈염화 반응거동 반응생성물의 고형화 특성을 조사하였다. LiCl계 폐기물과 달리, LiCl-KCl폐기물의 반응은 두 개의 온도범위에서 반응이 진행되며, $400^{\circ}C$의 경우에는 LiCl이, 약 $700^{\circ}C$에서는 KCl이 주로 반응하는 것으로 확인되었다. 여러 가지 반응실험을 통하여 LiCl-KCl의 탈염화 반응에 가장 적합한 물질은 SAP 1071 (Si/Al/P=1/0.75/1 in molar)인 것으로 확인되었다. 4가지 종류의 고형화 실험을 통하여 고화체의 bulk shape과 densification은 SAP/Salt의 비에 영향 받는 것을 확인하였다. 제조된 고형화 시료는 Product Consistency Test-A법을 이용하여 기본적인 내구성을 평가하였다. 본 연구는 $SiO_2$, $Al_2O_3$, $P_2O_5$로 이루어진 탈염화 물질을 이용하여 반응특성과 고형화 특성에 대한 기본적인 정보를 제공하였으며, 이와 같은 실험을 통하여, 본 연구에서 제안된 탈염화 고화처리방법이 휘발특성이 높고 기존 유리매질과 상용성이 낮은 금속염화물계 폐기물에 적용이 가능함을 확인하였다.
김나영,은희철,박환서,안도희,Kim, Na-Young,Eun, Hee-Chul,Park, Hwan-Seo,Ahn, Do-Hee 한국방사성폐기물학회 2017 방사성폐기물학회지 Vol.15 No.1
The pyroprocessing of spent nuclear fuel generates LiCl-KCl eutectic waste salt containing radioactive rare earth nuclides. It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste in a hot-cell facility. In this study, capture and solidification of a rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with a $Li_2O-Al_2O_3-SiO_2-B_2O_3$ system was conducted to simplify the existing separation and solidification process of rare earth nuclides in LiCl-KCl eutectic waste salt from the pyroprocessing of spent nuclear fuel. More than 98wt% of Nd in LiCl-KCl eutectic salt was captured when the mass ratio of the composite was 0.67 over $NdCl_3$ in the eutectic salt. The content of $Nd_2O_3$ in the Nd captured-composite reached about 50wt%, and this composite was directly fabricated into a homogeneous and chemical resistant glass waste in a monolithic form. These results will be utilized in designing a process to simplify the existing separation and solidification process.
금속고화체용 STS304-Zr 합금의 미세조직과 파괴거동에 미치는 열처리의 영향
김종우,장선아,한승엽,박환서,이정훈,이성학,권용재,이정구,신상용,Kim, Jongwoo,Jang, Seon Ah,Han, Seung Youb,Park, Hwan Seo,Lee, Junghoon,Lee, Sunghak,Kwon, Yongjai,Lee, Jung Gu,Shin, Sang Yong 한국재료학회 2018 한국재료학회지 Vol.28 No.3
Three kinds of STS304-Zr alloys were fabricated by varying the Zr content, and their microstructure and fracture properties were analyzed. Moreover, we performed heat treatment to improve their properties and studied their microstructure and fracture properties. The microstructure of the STS304-Zr alloys before and after the heat treatment process consisted of ${\alpha}-Fe$ and intermetallics: Zr(Cr, Ni, Fe)2 and Zr6Fe23. The volume fraction of the intermetallics increased with an increasing Zr content. The 11Zr specimen exhibited the lowest hardness and fine dimples and cleavage facets in a fractured surface. The 15Zr specimen had high hardness and fine cleavage facets. The 19Zr specimen had the highest hardness and large cleavage facets. After the heat treatment process, the intermetallics were spheroidized and their volume fraction increased. In addition, the specimens after the heat treatment process, the Laves phase (Zr(Cr, Ni, Fe) 2) decreased, the Zr6Fe23 phase increased and the Ni concentration in the intermetallics decreased. The hardness of all the specimens after the heat treatment process decreased because of the dislocations and residual stresses in ${\alpha}-Fe$, and the fine lamellar shaped eutectic microstructures changed into large ${\alpha}-Fe$ and spheroidized intermetallics. The cleavage facet size increased because of the decomposition of the fine lamellar-shaped eutectic microstructures and the increase in spheroidized intermetallics.
화상처리를 이용한 유연성디스크 가공 평면구간 측정에 관한연구
노대호(Dae Ho Roh),박환서(Hwan Seo Park),이홍국(Hong Guk Lee),신관수(Kwan Soo Shin),유송민(Song Min Yoo) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.5
The goal of this study is to simplify the measurement process of the flat zone length produced by a flexible disk grinding system for the process automation. The image of workpiece in the grinding process is obtained, and the cutting speed and the feeding speed are controlled carefully to maximize the flat zone length. The gradient, the inflection point and the length of the line in the image are calculated, and the length is also measured by using a projector. Processing conditions and inversely proportional to flat zone length was changing. The flat zone length is estimated by Neural network algorithm considering the process conditions with the estimated error range as 0.06~3.61%, the Neural network algorithm for the grinding process estimation is found to be useful for building the process automation database.