RPI모형을 이용한 ULPU-V시험의 수치모사 = Numerical Simulation on the ULPU-V Experiments using RPI Model

다국어 초록 (Multilingual Abstract)

The external reactor vessel cooling (ERVC) is well known strategy to mitigate a severe accident at which nuclear fuel inside the reactor vessel is molten. In order to compare the heat removal capacity of ERVC between the nuclear reactor designs quantitatively, numerical method is often used. However, the study for ERVC using computational fluid dynamics (CFD) is still quite scarce. As a validation study on the numerical prediction for ERVC using CFD, the subcooled boiling flow and natural circulation of coolant at the ULPU-V experiment was simulated. The commercially available CFD software ANSYS-CFX was used. Shear stress transport (SST) model and RPI model were used for turbulence closure and wall-boiling, respectively. The averaged flow velocities in the downcomer and the baffle entry under the reactor vessel lower plenum are in good agreement with the available experimental data and recent computational results. Steam generated from the heated wall condenses rapidly and coolant flows maintains single-phase flow until coolant boils again by flashing process due to the decrease of saturation temperature induced by higher elevation. Hence, the flow rate of coolant natural circulation does not vary significantly with the change of heat flux applied at the reactor vessel, which is also consistent with the previous literatures.

참고문헌 (Reference)

1 M. Jamet, "Validation of NEPTUNE CFD on ULPU-V experiments" 293 : 468-475, 2015

2 F. Menter, "Two-equation Eddy-viscosity Turbulence Models for Engineering Applications" 32 (32): 269-289, 1984

3 B. R. Sehgal et al., "Nuclear Safety in Light Water Reactors, Academic Press" 2012

4 N. Kural, "Multidimensional Effects in Forced Convection Subcooled Boiling" 1990

5 B. Koncar, "Modelling of Local Two-phase Flow Parameters in Upward Subcooled Flow Boiling at Low Pressure" 47 : 1499-1513, 2004

6 T-N. Dinh, "Limits of Coolability in the AP1000-Related ULPU-2400Configuration V Facility" CRSS Technical Report 0306 2003

7 ANSYS, "ANSYS CFX-Solver Manager User’s Guide" 2013