V-500 SKID is an integral PWR in which the core and steam steam generators (SG) are contained within the steel pressure vessel, Fig.2. The

pressurizer is located apart from the pressure vessel. The guard tube block shroud is of 2.8 m in diameter and it separates riser and downcomer parts of the coolant circulation path. The hot coolant moves from the core through the riser and upper shroud windows into the steam generators located in the downcomer. The coolant moves due to the difference in coolant densities in the downcomer and riser. The pressurizer is connected, by two pipelines, to the reactor pressure vessel and the water clean up system. Injection of cold water into the pressurizer improves the pressurizer parameters.