Steady and transient natural convection with volumetric energy sources in a fluid layer bounded from below by a segment of a sphere. Annual report, July 1976--September 1977

In the event of a core-melt accident in a nuclear power reactor, the possibility exists for the molten core material to form a lenticular shaped layer either at the bottom of the reactor vessel or in the ex-vessel containment. Such a layer will have a flat upper surface and a lower surface comprising a segment of a sphere. This report presents the results of an experimental study of natural convection in an internally heated, single-phase fluid layer bounded from below by a segment of a sphere. Steady-state heat transfer coefficients are determined as a function of the Rayleigh number for a range of layer geometries, i.e., various layer depths and aspect ratios. The thermal boundary conditions maintained throughout the study are an insulated, rigid lower boundary and an isothermal, rigid upper boundary. As a model of a possible core-melt configuration, the present experiments provide heat transfer data in a situation wherein the convective transport process conservatively represents any single-phase convective process that can occur in the core melt, thermal radiation within the core melt is absent, and all of the heat flow is upward