Effects of Initial Pressure and Length of a Broken Pipe on the Transient Hydraulic Loads Acting on Nuclear Steam Generator Tubes and Supports During Blowdown Following a Sudden Feedwater Pipe Break

This paper investigates the effects of steam generator initial pressure and length of a broken feedwater pipe on the transient hydraulic loads on the pressurized water reactor (PWR) steam generator (SG) tubes and supports during blowdown following a sudden feedwater line break (FWLB). To do this, the transient flow fields inside the SG and the connected broken feedwater pipe are calculated by realistically treating the discharge flow as the sub-cooled water flashing flow. Then, the calculated transient flow field data are used to predict the transient hydraulic loads on the PWR SG tubes and supports for some specified cases where the SG initial pressure or the broken feedwater pipe length are different from each other.

Influences of Fluidic Interfaces on the Formation of Fine Scale Structure by Chaotic Mixing

A numerical model has been developed of two-dimensional chaotic mixing of immiscieble Newtonian fluids. A computationally efficient numerical methodology is employed which is well-suited to complex, evolving interfaces. Mixing was confined to a rectangular cavity with periodically driven upper and lower surfaces. Interfacial forces and the transient flow fields in each phase were considered to assess specifically the influences on interfacial morphology of interfacial tension and phase viscosity ratio under creeping flow conditions. Predicted morphologies are compared to those of solidified specimens synthesized by chaotic mixing in companion studies.