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소듐냉각고속로 핵연료 집합체의 취급 및 운송시 구조건전성 평가
이현승(Hyun-Seung Lee),윤경호(Kyung-Ho Yoon),김형규(Hyung-Kyu Kim),천진식(Jin-Sik Cheon),이찬복(Chan-Bock Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The Korea Atomic Energy Research Institute(KAERI) has been developing Sodium-cooled Fast Reactor(SFR). A fuel assembly was main components of SFR. Fuel assembly must maintain structural integrity because it was contained fuel rods. One of the evaluation of structural integrity was the handling and transport conditions. A load that may occur during transport and handling of the fuel assemblies was considered. In consideration of safety, the load was applied 6 times self weight. This paper was to evaluate the structural integrity during handling and transportation of the fuel assembly.
이현승(Hyun Seung Lee),윤경호(Kyung Ho Yoon),천진식(Jin Sik Cheon),이찬복(Chan Bock Lee) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
The CA (Control Assembly) of PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor) has a CRA (Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop. In General, dynamic behavior analysis in fluids using CFD commercial code such as CFX and FLUENT. However, it is not suitable for parameter study of damping system design of control assembly because commercial code requires a lot of resource. So, KAERI developed the in-house code called HEXCON that predict dynamic behaviors (drop elevation, velocity and acceleration) of CRA. Shape of the damper and CRA was modified by considering the results of HEXCON. The impact analysis of the modified model under normal/abnormal drop conditions was performed to evaluate structural integrity using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.
안전정지지진 조건에서 소듐냉각고속로 핵연료 집합체의 Lifting-off 해석
이현승(Hyun-Seung Lee),윤경호(Kyung-Ho Yoon),김형규(Hyung-Kyu Kim),천진식(Jin-Sik Cheon),이찬복(Chan-Bock Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The Korea Atomic Energy Research Institute(KAERI) has been developing Sodium-cooled Fast Reactor(SFR). The stability of the fuel assembly of SFR, supported on the grid plate and held position by self weight. Top of fuel assembly has free boundary conditions. Hence, there is a concern of lifting off during SSE(Safe Shutdown Earthquake). Therefore, it is necessary to carry out the evaluation of the lifting-off of fuel assembly under vertical acceleration in consideration of the SSE.
낙하충격에 의한 소듐냉각고속로 제어봉집합체의 건전성 평가
이현승(Hyun Seung Lee),윤경호(Kyung Ho Yoon),김형규(Hyung Kyu Kim),천진식(Jin Sik Cheon),이찬복(Chan Bock Lee) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.3
소듐냉각고속로의 제어집합체는 내부덕트 및 제어봉을 갖는 제어봉집합체를 포함하고 있다. 제어봉집합체는 비상시 긴급 정지를 위하여 중력에 의하여 제어집합체 덕트내에서 낙하한다. 제어봉집합체의 낙하 시간과 충격 속도는 반응삽입시간 및 구조건전성에 관하여 중요한 변수이다. 본 연구의 목적은 낙하 충격에 의한 제어봉집합체의 동적거동 및 건전성평가를 조사하는 것이다. 제어봉집합체의 정상/비정상 낙하조건에서의 충격 해석은 상용 유한요소코드인 LS-DYNA를 사용하여 수행하였다. 낙하 충격 해석 결과, 제어봉집합체는 구조건전성을 유지하고 있으며, 비정상 조건에서도 댐퍼의 유동홀에 정상삽입 되었다. The CA (Control Assembly) of an SFR has a CRA(Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop impact. The impact analysis of the CRA under normal/abnormal drop conditions was carried out using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.
소듐냉각고속로 피복관용 중형 HT9 단조품 소재의 미세조직 및 기계적 특성 평가
김준환,이강수,김성호,이찬복,Kim, Jun-Hwan,Lee, Kang-Soo,Kim, Sung-Ho,Lee, Chan-Bock 한국방사성폐기물학회 2012 방사성폐기물학회지 Vol.10 No.1
소듐냉각 고속로 (SFR) 핵연료 피복관 후보재료로 고려되고 있는 중형 규모의 HT9 단조품 소재에 대한 금속조직학적 영향을 고찰하였다. 시험 재료는 유도가열법을 이용하여 1.1톤 규모의 잉곳으로 성형한 후, $1170^{\circ}C$에서 고온 단조 및 공랭을 통하여 160mm 직경 및 7000mm 길이를 갖는 단조품으로 가공하여 반경방향으로 미세조직의 변화를 관찰하였다. 시험 결과 시험 재료는 페라이트-마르텐사이트 조직을 보였으며 합금 조성에 의하여 2~3%의 델타 페라이트 (delta ferrite)를 가짐과 동시에 반경방향의 냉각속도 차이에 의하여 최대 15%의 변태 페라이트 (transformed ferrite)를 함유함이 관찰되었다. 냉각곡선의 모델링과 시간-온도-변태 (TTT) 선도를 이용한 민감도 분석을 통하여 단조품의 직경을 120mm로 줄였을 경우 중심부의 변태 페라이트 형성을 억제할 수 있음을 제시하였다. Microstructural and mechanical property were evaluated at the medium-sized HT9 (12Cr-1MoWV) forged steel which was considered as primary candidate for the fuel cladding in sodium-cooled fast reactor (SFR). Material was forged at $1170^{\circ}C$ after the induction melting to make round bar as 160mm diameter, 7000mm length then the radial distribution of microstructure as well as microhardness was evaluated. The results showed that overall microstructure exhibited as ferrite-martensite structure, where small amount (2~3%) of delta ferrite was formed throughout the specimen and maximum 15% of transformed ferrite was formed at the center, where it gradually decreased toward the radial direction. Sensitivity analysis of the cooling curve and Time-Temperature-Transformation (TTT) diagram revealed that formation of transformed ferrite could be avoided when the diameter was decreased down to 120mm.
소듐냉각고속로 U-Zr 핵연료집합체 제조장치 설계요건 개발
이영호(Young-Ho Lee),박정용(Jeong-Yong Park),김준환(Jun-Hwan Kim),이찬복(Chan-Bock Lee),김성호(Sung-Ho Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
PGSFR 초기노심에 적용할 U-Zr 핵연료집합체 제조장치에 대한 설계요건과 이를 바탕으로 개념설계를 수행하였다. 핵연료집합체 제조장치는 크게 조립장치와 검사장치로 구분하였으며, 조립장치는 연료봉 번들 조립 및 집합체 조립, 용접장치로 분류하였고 검사장치는 핵연료집합체 고정장치 및 치수 검사장치로 분류하여 설계하였다. 현재까지 수행된 핵연료집합체 설계에서 각 부품간 공차가 매우 작아 이를 극복하기 위한 장치의 구성은 향후 상세설계단계에서 수행되어야 할 것으로 보인다. 또한 본 장치가 설치될 시설과의 호환성을 고려하여 기계적 조립 및 동력 등 상세한 항목에 대한 설계요건이 추가되어야 할 것으로 판단된다. In this study, design criteria of fuel assembly manufacturing system for sodium-cooled fast reactor is reviewed focusing on the optimized manufacturing procedure, handling of hexagonal duct, maintaining rod bundle shapes, tight tolerance of each assembling part, application of welding method, etc. A time-consuming procedure was assembling of rod bundle because each fuel rod should be stacked one by one due to its outer wire spacer. A laser welding was selected as joining method between hexagonal duct and nose piece in consideration of operation period, maintenance,
논문 : 금속연료-피복재 상호확산 거동에 미치는 기상증착법의 영향
김준환 ( Jun Hwan Kim ),이병운 ( Byoung Oon Lee ),이찬복 ( Chan Bock Lee ),지승현 ( Seung Hyun Jee ),윤영수 ( Young Soo Yoon ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.7
This study aimed to evaluate the performance of diffusion barriers in order to prevent fuel-cladding chemical interaction (FCCI) between the metallic fuels and the cladding materials, a potential hazard for nuclear fuel in sodium-cooled fast reactors. In order to prevent FCCI, Zr or V metal is deposited on the ferriticmartensitic stainless steel surface by physical vapor deposition with a thickness up to 5㎛. The diffusion couple tests using uranium alloy (U-10Zr) and a rare earth metal such as Ce-La alloy and Nd were performed at temperatures between 660~800℃. Microstructural analysis using SEM was carried out over the coupled specimen. The results show that significant interdiffusion and an associated eutectic reaction ocurred in the specimen without a diffusion barrier. However, with the exception of the local dissolution of the Zr layer in the Ce-La alloy, the specimens deposited with Zr and V exhibited superior eutectic resistance to the uranium alloy and rare earth metal.
금속연료-피복재 상호확산 방지를 위한 크롬 도금법 적용 연구
김준환 ( Jun Hwan Kim ),이강수 ( Kang Soo Lee ),양성우 ( Seong Woo Yang ),이병운 ( Byoung Oon Lee ),이찬복 ( Chan Bock Lee ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.12
Studies have been carried out in order to reduce fuel-cladding chemical interaction (FCCI) behavior of metallic fuel in sodium-cooled fast reactors (SFR) using an electroplating technique. A 20㎛thick Cr layer has been plated by the electrochemical method in the Sargent bath over the HT9 (12Cr-1Mo) clad material and diffusion couple tests of the U-10Zr metallic fuel as well as the rare earth alloy (70Ce-29La) have been conducted. The results show that the Cr plating can prevent FCCI behavior along the fuel-clad interface. However, cracks developed through the thickness during plating, which resulted in the migration of some fuel constituents. Variation of bath temperature, application of pulse current, and post heat treatment have been conducted to control such cracks. We found out that some conditions like the pulse current and the post heat treatment enhanced the layer property by reducing the internal cracks and improving the diffusion couple test.