Investigation of quenching phenomena during the relooding phase against the FLECHT-SEASET experiment by using RELAP5/MOD3.3

Duong Thanh Tung 1, Tran Thanh Tram 1, Hoang Tan Hung 2, Nguyen Thanh Thuy2
1 Nuclear Training Center, Vietnam Atomic Energy Institute
2 Institute for Nuclear Science and Techniques

Main Article Content

Abstract

The reflood model of RELAP5/MOD3.3 (patch 4) was assessed by using the FLECHT-SEASET tests. The tests were conducted to have a better understanding of the postulated loss of coolant accident in a light water reactor (LWR). The best-estimate system analysis code was used to simulate these accident scenarios, especially in Design Basic Accident such as Loss-Of-Coolant-Accident (LOCA). The primary purpose of this report was to assess the accuracy of a computer system analysis code by using RELAP5/MOD3.3 in comparison to actual test results taken from the FLECHT-SEASET tests in which the reflood model was built in. In RELAP5’s simulation cases, the various boundary and initial conditions, such as power supplied and reflooding rate were selected. As a result, the RELAP5 looked to be accurate in predicting the quenching time and rod surface temperature for this particular case. However, the RELAP5 code under-estimated the rod surface temperature in comparing with the experimental data of the FLECHT-SEASET tests. Accordingly, for this high flooding rate and particular reactor power level that the reflooding model in RELAP5 could be possible used for predicting the reflooding phenomena during the LOCA accident.

Article Details

References

[1]. L. E. Hochreiter, Fan-Bill Cheung, et al. “RBHT Reflood Heat Transfer Experiments Data and Analysis”, 2012, USNRC.
[2]. M.J. Loftus, L.E. Hochreiter, C. E. Conway, C. E. Dodge, A. Tong, E. R. Rosal, M. M. Valkovic, S. Wong, “PWR Flecht Seaset Unblocked Bundle, Forced and gravity reflood task: Data report”, Volume 1, 1980, Program Jointly sponsored by USNRC, EPRI and Westinghouse.
[3]. P. Ihle, K. Rust, “FEBA Flooding Experiments with Blocked Arrays Evaluation Report”, (1984).
[4]. Bud Dong Chung et al., “Improvements to the RELAP5/MOD3 Reflood Model and Uncertainty Quantification of Reflood Peak.
Clad Temperature”, The Agreement on Research Participation and Technical Exchange, International Code Assessment and Maintenance Program (CAMP). U.S. Nuclear Regulatory Commission; 1996.
[5]. Zbigniew Koszela, “Assessment of RELAP5/MOD3.2.2 Gamma against ABB Atom 3 × 3-Rod Bundle Reflooding Tests”, Nuclear Engineering and Design 223 (2003) 49–73.
[6]. Tong Soo Choi, Chang Hwan Ban, “Improvement of the reflood model of RELAP5/MOD3.3 based on the assessments against FLECHT-SEASET tests”, Nuclear Engineering and Design 240 (2010) 832–841.
[7]. G.Th Analytis, “Developmental Assessment of RELAP5/MOD3.1 with Separate Effect and Integral Test Experiments: Model Changes and Options”, Nuclear Engineering and Design 163 (1996) 125–148.
[8]. USNRC, “RELAP3.3/MOD3.3 Code Manual-Volume IV: Models and Correlations “NUREG/CR-5535/Rev P4-Vol IV, 2010.