High pressure melt ejection relevant to CANDU reactors

The modelling of fuel-coolant interaction following a severe flow blockage in a single channel of a CANDU reactor is assessed. The available data that support these models is also reviewed. It is concluded that it is appropriate to employ the forced fuel-coolant interaction methodology in analyzing CANDU single channel flow blockage event with a severe power-cooling mismatch. The hydrodynamic transients are conservatively determined for various amounts of molten fuel available for discharge. The magnitude of the pressure transient and impulse loads decrease as the distance from the rupture site increases. The higher discharged mass produces more energy deposited in the bubble over the transient which results in a faster and greater pressurization of the moderator and results in higher impulsive loads on adjacent structures. (author)