The Possibility and the Effects of a Steam Explosion in the BWR Lower Head on Recriticality of a BWR Core
Activity Acronym:
SOS-2.3
Authors:
B.R. Sehgal & T.N. Dinh
Abstract:
The report describes an analysis considering a BWR postulated severe accident
scenario during which the late vessel automatic depressurization brings the water
below the level of the bottom core plate. The subsequent lack of ECCS leads to
core heat up during which the control rods melt and the melt deposits on the core
plate. At that point of time in the scenario, the core fuel bundles are still intact
and the Zircaloy clad oxidation is about to start. The objective of the study is to
provide the conditions of reflood into the hot core due to the level swell or a slug
delivered from the lower head as the control rod melt drops into the water. These
conditions are employed in the neutronic analysis with the RECRIT code to determine
if the core recriticality may be achieved.