[en] A series of single channel sodium boiling experiments were conducted in the Sodium Boiling Test (SBT) Facility at the Oak Ridge National Laboratory. The objective of these tests was to determine the maximum power that can be transferred to the coolant in a fuel assembly subchannel when the flow is driven by natural convection. Stable boiling was achieved for test times approaching one hour in duration for powers below the critical level. The power corresponding to dryout in these tests compares well with predictions from an earlier water simulation of fuel assembly voiding behavior