• Title/Summary/Keyword: Reflood

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Scaling Analysis of Thermal Hydraulics Phenomena in the Nuclear Reactor Vessel Downcomer during the Reflood Phase of LBLOCA (대형냉각재 상실사고 재관수 기간 동안, 차세대 원자로 강수부 내의 열수력 현상 모의를 위한 실험장치 척도해석)

  • Yun, B.J.;Song, C.H.;Kwon, T.S.;Euh, D.J.;Chu, I.C.;Yoon, Y.J.
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.821-827
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    • 2001

  • As one of the advanced design features of the Korea next generation reactor, direct vessel injection (DVI) system is being considered instead of conventional cold leg injection (CLl) system. It is known that the DVI system greatly enhances the reliability of the emergency core cooling (ECC) system. However, there is still a dispute on its performance in terms of water delivery to the reactor core during the reflood period of a large-break loss-of-coolant accident (LOCA). Thus, experimental validation is under progress. In this paper, a new scaling method, using time and velocity reduced linear scaling law, is suggested for the design of a scaled-down experimental facility to investigate the direct ECC bypass phenomena in PWR downcomer.

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Uncertainty Quantification of RELAP5/MOD3/KAERI on Reflood Peak Cladding Temperature (재관수 첨두 피복재 온도에 대한 RELAP5/MOD3/KAERI의 불확실성 정량화)

  • Park, Chan-Eok;Chung, Bub-Dong;Lee, Young-Jin;Lee, Guy-Hyung;Lee, Sang-Yong
    • Nuclear Engineering and Technology
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    • v.26 no.3
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    • pp.389-400
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    • 1994

  • The predictability of KAERI version of RELAP5/MOD3 on reflood peak cladding temperature during large break loss-of-coolant accident is assessed against 18 test runs in FLECHT SEASET test data. The associated uncertainty is statistically quantified. The selected test runs include a gravity feed test and several forced feed tests with wide range of the parameters such as flooding rate, system pressure, initial clad temperature, rod bundle power. The results show that the code under-predicts the peak cladding temperature by 7.56 K on average. The upper limit of the associated uncertainty at 95% confidence level is evaluated to be about 99 K, It including the bias due to the under-prediction.

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Assessments of FLECHT SEASET Unblocked Forced Reflood Tests Using RELAP5/MOD3 (RELAP5/MOD3 코드를 이용한 FLECHT SEASET의 강제 재관수 실험에 대한 평가)

  • Baek, Joo-Seok;Lee, Won-Jae;Lee, Sang-Yong;Kuh, Jung-Eui
    • Nuclear Engineering and Technology
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    • v.24 no.3
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    • pp.297-310
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    • 1992

  • FLECHT SEASET unblocked forced reflood tests are assessed using Apollo version of RELAP5/MOD3 5M5. The main purpose of the study is to examine the code predictability under forced reflood conditions having different initial power levels and flooding rates. Among various test matrices, the assessment calculations are performed for the test numbers 31701 31302, 31203, 31805, 34524, 31021, 34006 and 35807 These have been selected because they have similar initial conditions but different initial peak rod powers or flooding rates. In addition, various sensitivity calculations are performed for test number 31203 on the improved models of RELAP5/MOD3. Those are for the effect of Counter Current Flow Limit (CCFL) option at the outlet junction of the test section, for the effect of grid modelling on the interfacial drag calculations as well as on the heat structure calculations, and for the effect of nodalization and the time step size. The results of sensitivity studies show that the improved models of RELAP5/MOD3 enhance the code predictability. The assessment results show that the RELAP5/MOD3 has a tendency to underpredict the turn around temperature and the turn around time. But RELAP5/MOD3 silghtly overpredicts the turn around temperature for high flooding rate. The results also show that the calculated quenching by RELAP5/MOD3 is delayed with the increase of the rod power or the decrease of the flooding rate.

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