Evaluation of debris transport on containment floor during pool filling-up to continuous flow phase following a LOCA

For the purpose of evaluation of debris transport on containment floor of nuclear power plants, a model to calculate the transient flow field on the floor is developed. Two-dimensional shallow water equation (SWE) is solved by finite volume method (FVM) with unstructured triangular grid. The predictor-corrector method with an approximate Riemann solver of the Harten-Lax-van Leer (HLL) scheme is used to reserve second order accuracy in time and to capture water spreading on dry bed. An experiment of a dam-break is simulated. The present model is also applied in the calculation of the flow field of actual containment and the prediction result is discussed in terms of the transient behavior including the water spreading and the transient flow rates entering the Holdup Volume Tank (HVT). (author)