Experiment On the Excitation of Vapor Behavior and the Vibration by Thermal Flow Under C-Tube Pool Boiling Model

Abstract As an important safety equipment in AP1000, the passive residual heat removal heat exchanger (PRHR HX) with C- tube is responsible for timely removing heat from the reactor core in accident. A C-tube heating device was setup to investigate the flow characteristics of the in-containment refueling water storage tank (IRWST), and the vibration characteristics of the heat exchanger tube. The C-tube frequency in the pool boiling condition is 0-0.660 Hz. There is no resonance with the first natural frequency of 8.98 Hz. The IRWST temperature field can be divided into slow-heating period, fast-heating period, boiling period. Steam vapor exists in three periods, condensation and collapse of vapor concentrate on horizontal tube. The fast-heating period exists the subcooling degree ΔTsub for the most intense vapor excitation, ΔTsub is in the range of 13~16 °C. In term of thermal flow excitation vibration, the existence of the cross flow with C-plane direction is in the transition period from the slow-heating period to the fast-heating period, which excites the maximum RMS amplitude 0.039 mm and 0.034 mm at the midpoint of upper horizontal tube and vertical tube. When the fluid enters fast-heating period, the direction of flow changes into the normal C-plane. Normal RMS amplitude reached maximum 0.02 mm at upper 1/4 of the vertical tube in boiling period. The above research provides important data support for the safety and reliability of PRHR HX.