An Assessment of Steam-Explosion-Induced Containment Failure. Part II: Premixing Limits

The issues of transient and two-dimensional effects on fuel-coolant mixing in the lower plenum of a pressurized water reactor are addressed and resolved. Strong coolant depletion phenomena within fuel regions are analytically demonstrated. Quantification of premixtures under a variety of contact modes and conditions is used to specify the probable ranges of fuel mass available to participate in an explosion as a function of the core failure (melt pour) area.