Review studies on the state of the art of separate effects and component behaviour of LWR cooling systems

In the frame of the Shared Cost Action (SCA) Reactor Safety 1985-87 programme Review Studies on the state of the art of separate effects and component behaviour (preparation for a possible future experimental programme) have been performed. The final reports of three of the selected topics closely related and of particular interest for the development of specific two-phase models are collected in this volume: - Contact condensation effects relevant to ECC-water injection into a cold leg main coolant pipe (Contract 3002-86-07 ELISPD, Battelle Frankfurt) - State of the art of two phase steam water flow in piping junctions (Contract 3006-86-07 ELISPF, CEA-CEN Grenoble) - Critical investigation and model development for countercurrent flow of gas and liquid in horizontal and vertical channels (Contract 3007-86-07 ELISPD, Universitat Hannover). Specific conclusions are drawn and recommendations are given in each of the three papers. A common conclusion is that for developing more general models applicable to a wider range of situations further experimental work needs to be done but with emphasis on larger pipe diameters of test sections up to 30 mm and increasing the system pressures. For better understanding the physical phenomena local parameters and their variations need to be measured more accurately by applying better and more advanced instrumentation