A Preliminary Evaluation of a Generation IV Liquid Metal Fast Reactor Due to Sloshing and Thermal Stress

The aim of this paper is a preliminary evaluation of the load bearing capability of a generation IV molten metal cooled reactor (LMFR), with reference, as an example, to the ELSY project in the event of a safe shutdown earthquake (SSE). Two relevant safety aspects were considered and analyzed by means finite element (FEM) codes: the fluid-structure interaction and the high thermal loads due to the residual heat levels of the possible high burnup fuel. The first issue depends on the presence of a liquid free surface that especially in seismic accident conditions, allows for fluid motion (“sloshing”) and may have a significant influence on the reactor structures stress levels. The second aspect deals with the irradiated core heat source thermal effects after the reactor shutdown. In order to evaluate the reactor and internal components structural response capability for both high temperature and hydrodynamic loads, appropriate 3-D models were set up. Moreover preliminary thermal analyses were carried out by means of MCNPX and Origen2.2 codes in order to determine the transient input decay power after shutdown. The obtained preliminary results allowed to individuate the structures mostly affected by the assumed loading conditions in order to make possible an upgrading of the design geometry, should any be necessary, for the considered reactor design. The mentioned activities was a part of a CE funded 6^th FWP.