The Experimental Study On Flow Characteristics Of Large Subcooled Water In IRWST And Optimization Design Based On Scaled Model Of AP1000 ADS Under Depressurization Condition

In Containment Refueling Water Storage Tank (IRWST) and Automatic Depressure System (ADS) are new important equipments in three generations of nuclear power technology AP1000 nuclear power plant compared with two generations of nuclear power technology. In-containment refueling water storage tank (IRWST) acts as heat sink for passive residual heat removal heat exchanger (PRHR HX) under accident condition. In loss of coolant accident, steam is discharged into IRWST, reducing the pressure of the first loop. It can rapidly reduce pressure peak and temperature peak in containment, and alleviate the accident. Consequently, it is of great significance to study the flow characteristics of large undercooling water in IRWST under automatic depressurization condition.Based on the design of AP1000 power plant, a fully scaled experimental mock-up was built to simulate high-temperature and high-pressure steam spraying, steam condensation under depressurization condition through the analysis of the proportion. The experiment recorded the flow characteristics and 3D temperature and velocity distribution around sprayer in IRWST by dot matrix of thermocouples and Particle Image Velocimetry Particle Image Velocimetry (PIV)By studying the thermal stratification and natural circulation in the IRWST under depressurization condition when undercooling water is large, an optimization scheme was proposed to improve the efficiency of cooling water in IRWST.