A two dimensional finite difference modeling of the thermohydraulic behaviour of the PAHR debris bed up to extended dry out

A two dimensional numerical approach is presented for the prediction of post accident heat removal (PAHR) in liquid metal fast breeder reactors (LMFBR). The model is based on a finite difference solution of the relevant transport equations and includes the modeling of convective effects. Preboiling, equilibrium boiling, dry out onset and extended dry out regimes are covered. An original dry out model for chancelled beds is introduced and an acceptable agreement with the in pile tests performed at Sandia Laboratories is found. (orig.)