Solving chemical and mechanical problems of PWR steam generators

Steam generators in power plants, based on pressurized water reactors (PWRs), transfer heat from a primary coolant system (pressurized water) to a secondary coolant system. Primary coolant water is heated in the core and passes through the steam generator that transfers heat to the secondary coolant water to make steam. The steam then drives a turbine that turns an electric generator. Steam is condensed and returned to the steam generator as feedwater. Two types of PWR steam generators are in use: recirculating steam generators (RSGs) and once-through steam generators (OTSGs). Since most of the units are vertical, only vertical units are discussed in this article. Some vertical units have operated with a minimum of problems, while others have experienced a variety of corrosion and mechanically-induced problems that have caused unscheduled outages and expensive repairs.