Steam--water mixing studies related to emergency core-cooling system performance

A review is presented of recent experimental work related to the interactions between the primary-system fluid and emergency core-cooling (ECC) water in light-water-reactor systems during recovery from a postulated loss-of- coolant accident. The testing programs are exploratory separate-effects tests in reduced-size simulators of reactor systems. The tests address the cold-leg manometer loop, the cold-leg pipe--ECCS injection section, and the downcomer annulus--lower plenum regions of reactor systems. Data to date indicate the absence of cold-leg pipe plugging, the presence of oscillatory flow behavior initiated by full pipe flow, and the predominant role of condensation in both the injection section and annulus regions.