Natural convection for in-vessel retention at prototypic Rayleigh numbers

The ACOPO experiment simulates natural convection heat transfer from volumetrically heated pools at a half-scale reactor lower head geometry (hemispherical). New data for internal Rayleigh numbers of up to 1016 are presented, correlated and discussed, in relation to other available correlations. These ACOPO results confirm a key component of the in-vessel retention severe accident management strategy for an AP600-like design, as recently established in DOE/ID-10460.