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최재혁(Jae-Hyuk Choi),탁남일(Nam-Il Tak),신영준(Young-joon Shin),이기영(Ki-Young Lee) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
기존의 황-요오드 열화학적 수소생산 공정이나 황-하이브리드 수소생산 공정에서 요구되는 분해반응기는 고온의 헬륨이 분해반응에 필요한 열의 공급과 850℃ 이상의 적정 반응온도까지 반응기를 가열시키는 수단으로 고집적 열교환기 구조재의 열전도를 거치는 간접 열전달 방식을 취한다. 이러한 방식은 열교환 1차 유체와 2차 유체사이의 열전달 구조재의 850℃ 이상의 고온 부식 환경 노출로 인하여 분해반응기 장치재료 선정에 제한성을 초래하였다. 이러한 문제점을 완화하기 위하여 본 연구에서는 고온의 헬륨과 황에 의해 열전달을 형성하는 반응기를 예비설계하고 설계된 화학 분해반응기에 대하여 전산유체해석을 수행하였다. 해석 도구로서 상용 전산유체해석 코드인 CFX 5.7.1을 이용하였다. 알루미나 촉매 알갱이들이 존재하는 영역은 다공매체로 가정하였다. 다공매체 촉매층 영역에서의 열전달은 유효열전도도로서 간단히 모델링하였다. 분해 흡열반응을 고려하지 않은 보수적 계산외 본 연구 결과, 구조재료의 내력온도가 800℃ 이하를 유지하면서 반응기 내부 평균온도 850℃ 이상을 유지할 수 있는 분해반응기 구조와 운전조건을 도출할 수 있었다.
Experimental Apparatus to Study the Adsorption Behavior of Metals on Reactor Components
Sung-Deok Hong(홍성덕),Nam-il Tak(탁남일),Byung-Ha Park(박병하),Eung-Seon Kim(김응선),Min-Hwan Kim(김민환) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
Metallic fission product (FP), such as silver, cesium, and strontium, can be released from defected nuclear fuel of high temperature gas-cooled reactor (HTGR). These metals may subsequently diffuse from the fuel, become plate-out on the internal walls of primary components, leading to the introduction of radioactive impurities into many components of the reactor. Each material, each FP and each of its compound form have different kinetics and so, potentially, very large number of experiments are necessary. It should be understood that the empirical knowledge of FP alloy interactions makes no distinction between the different adsorption/absorption/reaction mechanisms. KAERI prepare a lab-scale apparatus to study plate-out characteristics of metallic FP. The apparatus is an out-of-pile test device and is able to simulate HTGR core temperature at helium flow condition or argon flow condition. The apparatus is an open loop that composed of a gas supply system, a preheater, a FP heater, a test section, an air cooler and two kind of filters. We invented multi-couponed tube type test section(MCTS) to get many test coupons with various temperature conditions. It is confirmed from a strontium metal test. Strontium in the crucible is entrained by argon gas flow and plated out on the MCTS successfully during 6.0 hours 900 ℃ steady-state operation of the experimental apparatus.
초고온가스로 핵분열생성물 거동해석용 전산 소프트웨어의 화학반응 모듈 개발
윤철(Churl Yoon),탁남일(Nam-il Tak),임홍식(Hong Sik Lim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
The Korea Atomic Energy Research Institute (KAERI) has been developing a computer software to analyze the behaviors of the fission products (FP) circulating in the primary coolant loop and in the containment for a very high temperature gas-cooled reactor (VHTR). This software, named GAMMA-FP (GAs Multicomponent Mixture Analysis- Fission Products module), consists of four interconnecting modules, which are the thermal dynamics module, the gaseous and the aerosol fission product analysis modules, and the chemical reaction module. The thermal dynamics module calculates the wall temperature and fluid properties as well as fluid velocities and temperatures within the control volumes, and transfers those data to the other modules. The aerosol FP module adopts a multi-component and multi-sectional aerosol analysis model (MAEROS model), and has been improved for 1-D aerosol transport. The gaseous FP module was developed to analyze the fission product plateout within the primary circuit as well as in the containment, which was validated against experiment data. In this study, strategies of the FP chemical reaction module development have been investigated. The general thermal equilibrium model was used for high temperature regions, and the frozen chemistry model was adopted for low temperature regions. The empirical chemisorption models were considered for the chemical reactions of radioactive FP gases with structural materials. These implemented chemical reaction models will be verified and validated in the next stage of the research.
강지호(Ji-Ho Kang),탁남일(Nam-Il Tak),김민환(Min-Hwan Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
A very high temperature reactor (VHTR) is designed to generate very high heat to approach outlet temperature goal which is typically around 1000 deg-C. The high temperature profiles make it difficult to assure the structural integrity of fuel assembly. The fuel blocks and the fuel compacts experience thermal stresses and significant dimensional changes in addition to the mechanical stresses caused by external forces. Therefore, it is necessary to assess the portion of thermal stresses and dimensional changes. However, precise assessment has not been done because of complexity of the fuel assembly geometry and absence of accurate temperature profiles. In this paper, full-scale finite element analysis (FEA) of one fuel block column in which 10 hexagonal fuel blocks are stacked was carried out using the temperature profiles calculated from computational fluid dynamics (CFD) analyses. The results showed that margin of safety of the fuel blocks and the fuel compacts is 0.88.
황-요오드 공정용 직접접촉 삼산화황 분해반응기내 열전달 특성에 관한 수치적 연구
최재혁(Jae-Hyuk Choi),신영준(Young-Joon Shin),탁남일(Nam-Il Tak),이기영(Ki-Young Lee),장종화(Jongwha Chang),정석호(Suk-Ho Chung) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A directly heated SO₃ decomposer for the sulfur-iodine and hybrid-sulfur processes has been introduced and analyzed by using a computational fluid dynamics code(CFD) with the CFX 5.7.1. The use of a directly heated decomposition reactor in conjunction with a VHTR allows higher decomposition reactor operating temperature. However, the thermochemical and hybrid hydrogen production processes accompanied with the high temperature and strongly corrosive operating conditions basically have material problems. In order to resolve these problems, we carried out the development of a structural material and equipment design technologies. The results show that the maximum temperature of the structural material (RA330) could be maintained at 800℃ or less. Also, it can be seen that the mean temperature of the reaction region packed with catalysts in the SO₃ decomposition reactor could satisfy the temperature condition of around 850 ℃ which is the target temperature in this study.