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액체금속로 고온배관의 미국 및 프랑스 설계지침을 따른 크리프-피로 손상평가
이형연(H.Y. Lee),김종범(J.B. Kim),유봉(B. Yoo) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
In the present paper, the evaluation procedures of creep-fatigue damage for the high temperature piping system of the liquid metal reactor(LMR) according to the design guidelines of ASME section Ⅲ subsection NH of US and RCC-MR of France are presented. The assessment of design integrity for the secondary piping of KALIMER(Korea Advanced Liquid Metal Reactor) has been carried out, which showed the present design of the KALIMER secondary piping satisfied the allowable limits of the two design guidelines for the creep-fatigue damage. The creep load condition is the steady state(511℃) during 30 years design lifetime at the secondary piping circuit with plant capacity factor of 85%. The number of refueling during the design lifetime is 20. The differences in evaluation procedures of ASME-NH, RCC-MR RB-3600 for the primary piping and RC-3600 for the secondary piping are presented.
액체금속로 Y-구조물의 비탄성 열응력 해석 및 손상평가에 관한 유한요소해석
곽대영,임용택,김종범,이형연,유봉,Kwak, D.Y.,Im, Y.T.,Kim, J.B.,Lee, H.Y.,Yoo, B. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.7
LMFBR(Liquid Metal Fast Breeder Reactor) vessel is operated under the high temperatures of 500-550.deg. C. Thus, transient thermal loads were severe enough to cause inelastic deformation due to creep-fatigue and plasticity. For reduction of such inelastic deformations, Y-piece structure in the form of a thermal sleeve is used in LMFBR vessel under repeated start-up, service and shut-down conditions. Therefore, a systematic method for inelastic analysis is needed for design of the Y-piece structure subjected to such loading conditions. In the present investigation, finite element analysis of heat transfer and inelastic thermal stress were carried out for the Y-piece structure in LMFBR vessel under service conditions. For such analysis, ABAQUS program was employed based on the elasto-plastic and Chaboche viscoplastic constitutive equations. Based on numerical data obtained from the analysis, creep-fatigue damage estimation according to ASME Code Case N-47 was made and compared to each other. Finally, it was found out that the numerical predictio of damage level due to creep based on Chaboche unified viscoplastic constitutive equation was relatively better compared to elasto-plastic constitutive formulation.
송기남,이형연,홍성덕,박홍윤,Song, Kee-nam,Lee, H-Y,Hong, S-D,Park, H-Y 한국압력기기공학회 2010 한국압력기기공학회 논문집 Vol.6 No.1
PHE(Process Heat Exchanger) is a key component required to transfer heat energy of $950^{\circ}C$ generated in a VHTR(Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. Korea Atomic Energy Research Institute established the gas loop for the performance test of components, which are used in the VHTR, and they manufactured a PHE prototype to be tested in the loop. In this study, as part of the high-temperature structural-integrity evaluation of the PHE prototype, which is scheduled to be tested in the gas loop, we carried out high-temperature structural-analysis modeling, thermal analysis, and thermal expansion analysis of the PHE prototype. The results obtained in this study will be used to design the performance test setup for the PHE prototype.
송기남,이형연,홍성덕,박홍윤,Song, Kee-nam,Lee, H-Y,Hong, S-D,Park, H-Y 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.2
PHE(Process Heat Exchanger) is a key component required to transfer heat energy of $950^{\circ}C$ generated in a VHTR(Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. Korea Atomic Energy Research Institute established a small-scale gas loop for the performance test of components, which are used in the VHTR, and they manufactured a PHE prototype made of Hastelloy-X to be tested in the small-scale gas loop. Results from the elastic structural analysis on the PHE prototype were reported in the previous article. In order to investigate the macroscopic structural characteristics and behavior of the PHE prototype under the test condition of the small-scale gas loop far more in detail, elastic-plastic high-temperature structural-analysis of the PHE prototype was carried out in this study.
CHABOCHE 통합 점소성 구성방정식을 이용한 재료거동해석
곽대영,임용택,김종범,이형연,유봉,Kwak, D.Y.,Im, Y.T.,Kim, J.B.,Lee, H.Y.,Yu, B. 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.11
Service conditions for structures at elevated temperatures in nuclear power plant involve transient thermal and mechanical load levels that are severe enough to caeuse inelastic deformations due to creep and plasticity. Therefore, a systematic mehtod of inelastic analysis is needed for the design of structural components in nuclear poser plants subjected to such loading conditions. In the present investigation, the Chabodhe model, one of the unified viscoplastic constitutive equations, was selected for systematic inelastic analysis. The material response was integrated based on GMR ( generallized mid-point rule) time integral scheme and provided to ABAQUS as a material subroutine, UMAT program. By comparing results obtaned from uniaxial analysis using the developed UMAT program with those from Runge-Kutta solutions and experimentaiton, the validity of the adopted Chaboche model and the numerical stability and accuracy of the developed UMAT program were verified. In addition, the developed material subroutine was applied for uniaxial creep and tension analyses for the plate with a hole in the center. The application further demonstrates usefulness of the developed program.
수정히스테리틱 Bi-Linear 면진베어린 모델을 사용한 지진응답감소
구경회,이재한,김종범,이형연,유봉,Koo, G.H.,Lee, J.H.,Kim, J.B.,Lee, H.Y.,Yoo, B. 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.1
In general, seismic isolators which are made of laminated rubber and shim plate have characteristics of complex hysteretic behavior. When shear deformation of the seismic isolator is small, the isolator hassimple hysteretic almost bi-linear behabior. But on large shear deformation hardening effects may occur. This paper proposes a moldeling method of the seimic isolator with modified hysteretic bi-linear model which can consider the hardening effects. From the results of the seismic analyses of the isolated system it is shown that the responses are singificantly reduced compared with those of the non-isolated system. The modified hysteretic bi-linear model of the isolator gives larger ZPA(zero period acceleration) than those of the simple hysteretic bi-linear model and the equivalunt spring-damper model.
송기남(Kee-nam Song),이형연(H-Y Lee),이수범(S-B Lee),김용완(Y-W Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Korea Atomic Energy Research Institute is in the process of carrying out a Nuclear Hydrogen Development and Demonstration (NHDD) Program by considering the indirect cycle gas cooled reactors that produce heat at temperatures in the order of 950 ℃. A coaxial double-tube hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger for the NHDD program. Recently, a preliminary design evaluation for the hot gas duct of the NHDD program was carried out. These preliminary design activities include a decision on the geometric dimensions, a strength evaluation, an appropriate material selection, and identifying the design code for the HGD. In this study, a preliminary strength evaluation for the HGD of the NHDD program has been undertaken based on the HTR-10 design concepts. Also, a preliminary evaluation of the creep-fatigue damage for a high temperature HGD structure has been carried out according to the draft code case for Alloy 617. Preliminary strength evaluation results for the HGD showed that the geometric dimensions of the proposed HGD would be acceptable for the design requirements.