Evaporator for Nuclear Power Plant

The evaporator is the core equipment for the secondary circuit energy conversion of a nuclear power plant. Its core function is to achieve efficient and safe conversion of nuclear energy into electrical energy through the physical isolation of the primary and secondary circuits. In a pressurized water reactor nuclear power plant, the evaporator (steam generator) is the key interface connecting the nuclear island and the conventional island, and has the dual functions of heat transfer and steam generation: the high-temperature and high-pressure coolant (about 330°C, 15.5 MPa) of the primary circuit flows from the core into the U-shaped tube bundle of the evaporator, transfers heat to the feed water on the secondary circuit side, generates saturated steam (pressure 5-7 MPa), and drives the steam turbine to generate electricity. The structural design of the evaporator (such as the use of corrosion-resistant nickel-based alloy Inconel 690 for heat transfer tubes and tube sheet thickness exceeding 500 mm) ensures that it can still maintain sealing under extreme working conditions, strictly isolates radioactive substances from entering the secondary circuit, and is an important barrier to the nuclear power plant's defense-in-depth system. Taking the third-generation nuclear power technology "Hualong One" as an example, its evaporator uses an integral forged tube plate and an optimized steam-water separation device, which increases the heat transfer efficiency by 15%, has an earthquake resistance of more than 0.3g, and a design life of 60 years. Modern evaporator technology also integrates intelligent monitoring systems (such as eddy current detection of heat transfer tube wall thickness and acoustic leak positioning), real-time warning of microcracks and corrosion risks, combined with modular manufacturing processes (a single evaporator weighs more than 400 tons), and the localization rate has exceeded 90%, supporting the dual upgrade of nuclear power plant safety and economy. From energy conversion efficiency (thermal efficiency exceeds 34%) to the ability to export waste heat under accident conditions, the evaporator has always been the core hub for the reliable operation of the nuclear power system.