B109 Experimental Study on Boiling Transition under Flow-Power Oscillating Condition for Hyper ABWR

In the envisioned high-power density core plant, the degradation of stability is concerned that is attributed to the shortening of rod heat conduction time constant upon the dense fuel grid and the increment of pressure drop caused by the wall friction. Under power and flow oscillated condition, the two-phase flow behavior might be different from that under the steady condition. Therefore, the thermal-hydraulic test using the rod bundle under the oscillation condition was performed to obtain the verification data for the analytical code. In this paper, the test results were described. It was found that the critical power decreased under flow oscillating condition, and the power oscillation had a little effect on the critical power.