A SHALLOW WATER EQUATION SOLVER AND PARTICLE TRACKING METHOD TO EVALUATE THE DEBRIS TRANSPORT

Debris transport on the containment floor following a loss-of-coolant accident (LOCA) of the Advanced Power Reactor (APR) 1400 plant is calculated. The plant does not have a switchover to recirculation operation and, thus, requires a fully transient analysis of debris transport. To calculate the flow field in a practical computational time and reasonable accuracy, two-dimensional Shallow Water Equations are solved using the Finite Volume Method. An approximate Riemann solver, Harten-Laxvan Leer (HLL) scheme is used to capture dry-to-wet interface. To calculate the debris particle transport, a simple two-dimensional Lagrangian particle tracking model including a drag force is developed. Some efficient schemes are implemented to search a hosting cell, to determine the intersection of a particle trajectory with a cell side, and to find the reflected position of particle. The hydraulic solver is validated with an open channel flow experiment. The present model is applied to calculate the transport fraction to Hold-up Volume Tank which is a unique flow path to the containment sump of the APR1400.