Seismic-Initiated Events Risk Mitigation in Lead-Cooled Reactors (SILER)

European Union

SILER is a project aimed at studying the risk associated with seismic initiated events in Generation IV Heavy Liquid Metal reactors and developing adequate protection measures. The attention is focused on the evaluation of the effects of earthquakes and on the identification of mitigation strategies in relation to both structures/components design as well as on the development of isolation devices. In this context, the seismically induced sloshing effects in the isolated ELSY-LFR reactor vessel were studied by IDOM.

Several transient dynamic analyses were performed in order to determine the sloshing effects of the molten lead in the reactor vessel and its internals due to the seismic action. Performed analyses used the ALE (Arbitrary Lagrange Euler) technique of space discretization in order to represent the fluid (molten lead) response. Contact surfaces were applied between the fluid and the structure.

The seismically induced sloshing in the ELSY-LFR reactor vessel with and without seismic isolators at the base of the reactor building was studied. For this purpose, only gravity and seismic loads were considered in the performed analyses. Four cases from the seismic input proportioned by the previous task of the SILER project were selected for the study.

Regarding the transient dynamic analyses, they were carried out in ABAQUS/Explicit. In a first approach, the structure was considered to perform as a rigid body and the fluid response was determined without taken into account the fluid-structure interaction. In a second approach, the flexibility of the main components was included in the analyses and the fluid structure interaction effects were analyzed.

Another goal of this study was to compare the obtained ABAQUS analyses results with results given by two other approaches, one performed with ANSYS-FLUENT and the other one, with the SPH (Smoothed-Particle Hydrodynamics) method. The ABAQUS approach is the one performed by IDOM.

Furthermore, IDOM proposed different plant layouts and design modifications in order to minimize the effects of earthquakes and seismic-induced phenomena such as tsunamis on the main structures. Specific attention was paid to all those components relevant to the safety of the plant, outlining possible solutions for protecting them, introducing barriers or enhancing safety by concentrating on specific components arrangement in the buildings.

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