381 / 2018-12-19 14:28:45

The Research of Steam Generator Thermal Performance Degradation in Ningde Nuclear Power Plant

Steam Generator ,Thermal Performance ,Nuclear Power Plant,steam pressure

全体主题 > 部件、设备和辅助设备

Steam generators are large shell and tube heat exchangers, containing several thousand tubes. They transfer heat from the primary reactor coolant to the secondary side to produce steam, which then powers turbine generators to produce electricity. Most nuclear power plants (NPP) have anywhere from 2 to 6 SG per reactor; however some designs have up to 12, with a total of more than 1300 SGs being in service in 357 of the total 450 reactors in the world. The performance of SG is critical to the overall efficiency and safety of an NPP, particularly as plant ages.As with any heat exchanger, the function of a nuclear steam generator is compromised by operational changes that increase the resistance to heat transfer between the primary and secondary fluids, lowering the efficiency and leading to thermal performance degradation. This type of performance degradation, the underlying causes, industry experience, and plant operational consequences had been discussed by ERRI and DEI reference documentations. After 6-10 years operation the steam pressure degradation of most plants occurred Ningde nuclear power plant was design for CPR1000 unit, which configuration of 55/19B type steam generator and half speed turbine. Every unit had three loops and three SGs. The steam pressure of steam generator (SG) in Ningde nuclear power plant decreased after the unit was in commercial operation. It decreased by 1 bar in first fuel cycle, and it was down by 0.5 bar at the second and third cycle. In this paper it concludes that the main cause of steam pressure loss is the sludge or fouling which accumulated at tubes and supporting plates at the second loop. According to the actual location of sludge in SG, the special bundle flushes an application was designed to reduce the sludge at the first tube sheet plant, and avoid the corrosion of heat transfer tubes. But it is a pity that the SG thermal performance was not recovered after this special flush. The sludge nearby the TSP1 was not the main cause of steam pressure loss.