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열성층 현상을 고려한 원전 안전주입계통 배관 열피로 평가
성희동(H.D. Sung),김선혜(S.H. Kim),김익중(I.J. Kim),김영진(Y.J. Kim),장윤석(Y.S. Chang),박정순(J.S. Park),최영환(Y.H. Choi) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In recent years, several piping failures caused by thermal stratification have been reported in some nuclear power plants. However, this kind of thermal fatigue was not considered when the old vintage nuclear power plants were designed. Thermal stratification usually is generated by turbulent penetration from RCS to branch line or leakage through damaged part of valve in branch line. In this research, using CFD analysis, characteristics of thermal stratification in a safety injection system of PWR plant were investigated and thermal fatigue evaluation was also conducted. To do this, first, CFD analyses were carried out on valve isolation model and out-leakage model. As a result, in valve insolation model, thermal stratification generated in front of 1st valve for a moment, however the temperature difference was small. In contrast, significant thermal stratification generated at the rear of 1st valve in out-leakage model. Therefore, thermal stress and fatigue evaluation were carried out based on the temperature result of out-leakage model.
김선혜,성희동,최재붕,허남수,박정순,최영환,Kim, Sun-Hye,Sung, Hee-Dong,Choi, Jae-Boong,Huh, Nam-Su,Park, Jeong-Soon,Choi, Young-Hwan 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.4
Turbulent mixing of hot and cold coolants is one of the possible causes of high cycle thermal fatigue in piping systems of nuclear power plants. A typical situation for such mixing appears in turbulent flow through a T-junction. Since the high cycle thermal fatigue caused by thermal striping was not considered in the piping fatigue design in several nuclear power plants, it is very important to evaluate the effect of thermal striping on the integrity of mixing tees. In the present work, before conducting detailed evaluation, three thermal striping evaluation methodology suggested by EPRI, JSME and NESC are analyzed. Then, a by-pass pipe connected to the shutdown cooling system heat exchanger is investigated by using these evaluation methodology. Consequently, the resulting thermal stresses and the fatigue life of the mixing tee are reviewed and compared to each other. Futhermore, the limitation of each methodology are also presented in this paper.
CANDU형 원전 주요기기의 피로손상 평가를 위한 그린함수 개발
김세창,성희동,최재붕,김홍기,송명호,노승환,Kim, Se Chang,Sung, Hee Dong,Choi, Jae Boong,Kim, Hong Key,Song, Myung Ho,Nho, Seung Hwan 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.4
For the efficient and safe operation of nuclear power plant, evaluating quantitatively aging phenomenon of major components is necessary. Especially, typical aging parameters such as stresses and cumulative usage factors should be determined accurately to manage the lifetime of the plant facility. The 3-D finite element(FE) model is generated to calculate the aging parameters. Mechanical and thermal transfer functions called Green's functions are developed for the FE model with standard step input. The stress results estimated from transfer functions are verified by comparing with 3-D FE analyses results. Lastly, we suggest an effective fatigue evaluation methodology by using the transfer functions. The usefulness of the proposed fatigue evaluation methodology can be maximized by combining it with an on-line monitoring system.