[3G01-06] Critical Heat Flux

[3G06] Prediction of Bubble Departure Diameter for Downward Facing Heating Surface with Different Inclination Angle in IVR Condition

*Md Abdur Rafiq Akand¹, Tatsuya Matsumoto¹, Wei Liu¹, Koji Morita¹ (1. Department of Applied Quantum Physics & Nuclear Engineering, Kyushu University, Japan)

Keywords:Orientation angle, Bubble departure diameter, Subcooled flow boiling, Force balance, Numerical solution

The concept of In-Vessel Retention (IVR) has been considered a viable strategy to maintain the reactor pressure vessel (RPV) integrity in case of a severe reactor accident. The success of this strategy heavily depends on the critical heat flux distribution of the bottom outer surface of the reactor vessel and critical heat flux models require accurate knowledge of bubble departure diameter as well as net vapor generation point to intensify their accuracies. A simplified force-balance model on subcooled flow boiling is proposed to calculate the bubble departure diameter for downward facing heating surface including the effect of inclination angles in IVR condition. The force-balance is a third-order polynomial equation and it is solved numerically to calculate the bubble departure diameter. The calculated diameter using the proposed model at different inclination angles, mass flux, heat flux, and pressure shows a fairly good agreement with the experimentally measured values.