[en] Accident analysis of an HCDA in an LMFBR often involves consideration and calculation of thermal hydraulic events related to boiling pools of fuel and steel mixtures in the disrupted core, as well as the subsequent motion of these two-phase mixtures out of the core. In many cases, the thermal-hydraulic state of the boiling fuel-steel or fuel pool may determine the initial or boundary conditions for subsequent calculations. Calculations of boundary heat losses are directly dependent on knowledge of the local and pool-average void fraction, and assessment of models to predict the average void fraction depends on the availability of these experimental data. Experiments have been performed to determine the distribution of boundary heat losses from volume-heated boiling pools and the pool-averaged void fraction