Thermal hydraulic consequences of primary pipe rupture

Thermal hydraulic analyses of primary pump pipe rupture event have been carried out with the objective of (i) estimating the temperature rise in the fuel, cladding and coolant, (ii) investigation of possible flow redistribution in subassemblies and (iii) investigation of the formation of vapour bubbles due to flashing, resulting in reactivity addition in the core. For this purpose one dimensional studies using thermal and hydraulic models of the core SA and primary sodium circuit, three dimensional studies of grid plate using the CFD code PHOENICS and one dimensional studies using pressure transient codes have been carried out. Analysis indicates that the core flow is reduced to 30% during the transient and specified temperature limits of this category of events are respected. There is no flow redistribution among various subassemblies and no formation of vapour in subassemblies. (author)