A Study of Subcooled Film-Boiling Heat Transfer Under Reactivity-Initiated Accident Conditions in Light Water Reactors

The empirical correlations for subcooled film-boiling heat transfer during a reactivity-initiated accident in light water reactors are derived from inverse heat conduction calculations using the cladding surface temperatures measured in in-reactor experiments. The experimental data for cold startup conditions (subcoolings of ∼10 to 80 K and coolant velocities of ∼0 to 2 m/s at atmospheric pressure) and hot standby conditions (subcooling of ∼10 to 40 K, system pressures of 7.2 and 16 MPa, and system temperatures of 550 and 580 K) are used for this investigation. The present correlations are compared with existing correlations from ex-reactor experiments. The results of transient fuel behavior calculations with a computer code that included the present correlations are in good agreement with the corresponding measured data from the experiments.