Gen-IV pool reactors: Validation of sloshing CFD modelling and behavior under large seismic events

Abstract

This paper addresses one aspect of the safety of compact lead-cooled pool fast reactors. Under a seismic event, there is concern that the surface sloshing could compromise the integrity of some structures or components. We investigate this issue by means of computational modelling and simulation using the STAR-CCM + commercial software.

In the first part, we simulate a partially filled vertical cylinder under harmonic forcing and quantitatively validate the modelling by comparison with experimental data of the free-surface height at different locations. Specifically, we capture with a very high precision a behavioral transition of the amplitude-frequency map near resonance.

In the second part, the modelling is applied to a fast reactor mock-up in water. It is validated again by comparison with experimental data under harmonic forcing. The numerical mock-up is then subjected to four seismic events of increasing intensity. The free-surface height and the forces applied to the mock-up vessel are monitored.

It is found that the forces applied to the vessel are strongly dominated by the highest frequency of the seismic acceleration. By applying a high filter cut at 1 Hz, the peak force is reduced by one order of magnitude but remains strongly related to the damped acceleration signal. Even then, sloshing forcing effects are observed but remain marginal.