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김민(Min Kim),정장규(Chang-Kyu Chung),김은기(Eun-Kee Kim),노태선(Tae-Sun Ro),이성노(Soung-No Lee),유성연(Seong-Yeon Yoo) 한국유체기계학회 2002 유체기계 연구개발 발표회 논문집 Vol.- No.-
The letdown system of pressurized water reactor (PWR) nuclear power plants had experienced instabilities in letdown system due to unacceptable flow characteristics of control valves. The Korean Standard Nuclear Power Plants (KSNPs) have three flow paths in parallel for letdown flow control. Each flow path consists of two orifices and one isolation valve. This study evaluates the effect of orifice arrangement and valve stroke time of letdown isolation valve on the system transients because sudden flow changes due to valve actuation can generate high pressure peaks in letdown line. A pressure transient analysis has been preformed to evaluate the impact of dynamic transients. This analysis uses MMS which is a simulation code developed by EPRI based on the method of characteristics. The result shows that the pressure peak is reduced in the continuous arrangement but negligible. Additionally, it shows that the stroke time of linear type plug valve greater than 15 seconds can give more stable performance.
노심용융사고 시 관통노즐이 제거된 원자로용기 하부헤드의 구조 건전성 평가
이연주,김종민,김현민,이대희,정장규,Lee, Yun Joo,Kim, Jong Min,Kim, Hyun Min,Lee, Dae Hee,Chung, Chang Kyu 한국전산구조공학회 2014 한국전산구조공학회논문집 Vol.27 No.3
본 논문에서는 노심용융사고 시 관통노즐이 제거된 원자로용기 하부헤드의 구조 건전성 평가를 수행하였다. 열응력, 노심용융물의 질량 그리고 내압조건의 해석결과를 고려할 때, 하부헤드의 열응력에 의한 영향이 가장 크게 나타났다. 손상 가능성은 파손기준에 따라 평가하였으며, 등가소성변형률이 임계변형률 파손기준보다 낮은 수준으로 평가되었다. 열-구조물 연성해석 결과 하부헤드의 두께 중간층에서 항복강도보다 낮은 응력이 발생한 탄성영역 구간을 확인하였다. 내압이 커지면서 탄성영역 범위가 점차 좁아지면서 탄성영역이 내벽으로 이동하는 결과를 확인하였고, 노심용융사고 시 구조적 건전성을 만족하는 것으로 평가되었다. In this paper, structural integrity evaluation of reactor pressure vessel bottom head without penetration nozzles in core melting accident has been performed. Considering the analysis results of thermal load, weight of molten core debris and internal pressure, thermal load is the most significant factor in reactor vessel bottom head. The failure probability was evaluated according to the established failure criteria and the evaluation showed that the equivalent plastic strain results are lower than critical strain failure criteria. Thermal-structural coupled analyses show that the existence of elastic zone with a lower stress than yield strength is in the middle of bottom head thickness. As a result of analysis, the elastic zone became narrow and moved to the internal wall as the internal pressure increases, and it is evaluated that the structural integrity of reactor vessel is maintained under core melting accident.
이상섭(Sang-Sud Lee),유성연(Seng-Yeon yOO),김병채(Byeong-Chae Kim),김은기(Eun-Kee Kim),임덕재(Duck-Jae Lim),정장규(Chang-Kyu Chung),김석벙(Seoung-Beom Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Naphthalene sublimation technique is used to investing the average and local heat transfer from the circular rod, and to determine the average and local heat transfer from the circular rod with and without squarc wing type mixing vane in axial flow. The experiments are performed for a circular rod and flat plate with and without mixing vane in wind tunnel. In comparison with flat plate and circular rod in axial flow, averaged Nusselts namber is increased 2 times as the increase of Reynolds namber with mixing vane. Longitudinal vortex induced by square wing type has the stronger vortex strength. so square wing type vortex generator shows an effect in downstream.