The decision for a nuclear power plant program may be based on differentconsiderations. Once the decision has been made the selection of the reactor typeof importance. World- wide a clear preference of the pressurized water reactor typeis shown by providing more than 65% of the installed capacity, that is in operationor under construction The actual status of nuclear engineering offers todaynuclear power reactors with an unit output of in the range of 1200 to 1500 MW oreven above. Smaller units in the range of 900 to 1000 MW which are still underconstruction are of old design. The main reason for the utilities to favor large unitsizes is their experience, that large units provide eco:1omicadvantages. Most ofthe suppliers, with few exceptions only, who develop new products focus on bigsizes to benefit from economy of scale effects. Some reasons or the plant size hasbeen increased to meet cost targets. R. Leverenz; Project Manager Nuclear Power International
