Reactor safety program applications and coordination. Task 1. Steam--water mixing program and system hydrodynamics. Task 55. Quarterly progress report, January--March 1976. [PWR]

Experimental studies are being conducted in a /sup 1///sub 15/-scale model of a four-loop pressurized water reactor at pressures to 60 psig to extend the understanding of steam-water interaction phenomena and processes associated with a loss-of-coolant accident. A series of penetration studies was undertaken in the /sup 1///sub 15/-scale, steel vessel model to define the effects of various parameters and operating conditions on water penetration to the lower plenum over a range of reverse core stream flow rates. The parameters investigated included lower plenum pressure level, injection water flow rate and subcooling, and cold leg stream flow. The operating conditions investigated included operation with reduced break area and varied containment back-pressure, operation with fixed intact cold leg steam, and operation with hydraulic communication between the intact cold leg and core steam supplies. Penetration studies were also undertaken in the /sup 1///sub 15/-scale, transparent vessel model to determine the effect on penetration of operation with the B and W loop arrangement together with direct annulus injection. Data are presented and discussed.