Full-scale critical flow test blowdown performancebased on the method of characteristics

Abstract

To obtain some maximal values of thermal-hydraulic characteristics in the blowdown phase of the loss of coolant accident, the blowdown performance of the discharge process is numerically simulated using one-dimensional two-phase hydrodynamic equations. For the nonlinear and coupling characteristics caused by severe convection in the physical process of discharge, the momentum equation and energy equation are decoupled by the method of characteristic (MOC). Then, the discrete solution of the control equations in the transient state is discretized and solved. Based on Marviken critical flow tests, the self-coding program and system analysis program RELAP5 are used to solve the equations. The effectiveness of the MOC is verified through a comparison of numerical simulation results and experimental data. In addition, the effects of the nozzle geometry and initial fluid state on the blowdown performance are studied, and the variation curves are obtained.