Boiling Transition and Heater Rod Temperature Change at THYNC Flow Oscillation Test

Abstract

It is known that the heater rod temperature changes periodically up and down under BWR instability condition, indicating the periodic occurrence of the boiling transition and rewetting due to the flow oscillation. When the heater power was increased further, the rod temperature was kept higher, indicating that the heat transfer mode changed to the continuous film boiling without rewetting. The power at the onset of the continuous film boiling under flow oscillation was depending on the flow amplitude and was lower than that under the stable condition. This was considered due to the delay of the rewetting against the flow rate recovery.