This publication is the final report of the INPRO collaborative project on advanced water cooled reactor (AWCR) case studies in support of passive safety systems. The participating Member States were Argentina, India and the Republic of Korea. It presents case study results on natural circulation and thermal stratification phenomena in selected passive safety systems, as well as major findings and conclusions drawn from these case studies. This publication will be a useful resource for researchers in the area of core physics and reactor thermohydraulics and for technical experts and engineers engaged in experimental investigation and theoretical simulation for developing passive safety systems.