Abstract

In a core meltdown accident in light water reactors, molten corium may drop into the lower plenum of the pressure vessel and interact with water, which is called fuel–coolant interaction (FCI). The behavior of the corium jet breakup in water during FCIs is important for the in-vessel retention strategy and has been extensively studied. While in previous studies, the jet cross-section shapes are naturally assumed to be circular, which is actually not always the case, in this study, the breakup processes of the corium jets with four different elliptical cross-section shapes and three different penetration velocities are simulated with color-gradient lattice Boltzmann method. The effect of the cross-section shape on the hydrodynamic breakup behavior of the corium jet is analyzed in detail. It is found that the effect of the cross-section shape on the jet penetration depth is very limited. With the increase in the aspect ratio under the same penetration velocity, the jet breakup length decreases gradually. In general, the dimensionless corium surface area increases with the increase in the aspect ratio for the jets under the same penetration velocity.

Highlights

  • During a core meltdown accident in light water reactors (LWRs), molten corium may drop into the lower plenum of the reactor vessel and interact with water, which is called fuel–coolant interaction (FCI)

  • The effect of the cross-section shape on the hydrodynamic breakup behavior of the corium jet is analyzed in detail

  • The snap shots of corium jet breakup processes along both minor axis direction and major axis direction of the elliptical cross-section in the 12 cases are presented in Figure 2, where the interface between the corium and the

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Summary

INTRODUCTION

During a core meltdown accident in light water reactors (LWRs), molten corium may drop into the lower plenum of the reactor vessel and interact with water, which is called fuel–coolant interaction (FCI). When the molten corium drops from the edge of the core, through the structures or the cracks of the corium crust, the corium jets are very likely to have different crosssection shapes depending on the specific situations (Corradini et al, 1988). The breakup process of the corium jets with four different elliptical cross-section shapes and three different penetration velocities are simulated with color-gradient LBM. The effect of the cross-section shape on the hydrodynamic breakup behavior of the corium jet is analyzed in detail

COLOR-GRADIENT LATTICE BOLTZMANN METHOD
Single-Phase Collision Operator
Recoloring Operator
COMPUTATIONAL DOMAIN AND PARAMETERS
Morphology of Corium Jet Breakup
Jet Penetration Depth
Jet Breakup Length
Degree of the Fragmentation
DATA AVAILABILITY STATEMENT
CONCLUSION

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