Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.
In Europe a great effort has been made in the Lead-Bismuth
Eutectic (LBE) technology, for use in the sub-critical reactors,
and its natural development is represented by the use of pure
lead that is less corrosive, chemically inert and in the foreseen
environment has good neutronic and thermal-hydraulic
characteristics, therefore it appears to be a suitable coolant for a
fast reactor.
The main purpose of this study deals with the evaluation of the
sloshing dynamic effects of lead coolant during a safety shut
down earthquake applied to a conceptual Lead-cooled Fast
Reactor (LFR) Generation IV (GEN IV) Nuclear Power Plant
design, with reference to the ELSY project system
configuration that is under development within the ongoing
European 7FW ELSY Program.
ELSY is an innovative small size pool-type reactor (600 MWe)
cooled by pure lead, characterized by a compact and simple
integrated primary circuit; by the way this configuration is
favourable from the point of view of the reduction of the
seismic loads and of the negative effect of the high lead density.
Therefore, the fluid-structure interaction problems and the free
oscillations of the heavy metal primary coolant attracted the
attention because during a strong motion earthquake the lead
surrounding the internals may be accelerated and the so-called
hydrodynamic interaction, due to the coolant sloshing, may
significantly influence the stress level in the reactor pressure
vessel (RPV).
To the purpose, the effect of the rigidity of adjacent internals
walls and coupling between coolant and vessel are considered
An adequate numerical modelling, by means a 3-D finite
element model, was set up and used for the foreseen structures
dynamic analysis, due to the inability of linear theory to
describe accurately the wave’s motion accounting for the
complex considered RPV geometrical aspect as well as the
material nonlinearities. Numerical results are presented and
discussed highlighting the importance of the fluid-structure
interaction effects in terms of stress intensity as well as the
capacity of internals and vessel walls to withstand wave’s
impact and prevent instabilities.
