[en] In this paper, recent developments of a quasi-Eulerian finite element formulation for the treatment of the fluid in fluid-structure interaction problems are described. The present formulation is applicable both to plane two-dimensional and axisymmetric three-dimensional problems. In order to reduce the noise associated with the convection terms, an amplification factor technique is used to implement an up-winding type scheme. The application of the method is illustrated in two problems which are of importance in nuclear reactor safety: (1) a two dimensional model of a cross section of a subassembly configuration, where the quasi-Eulerian formulation is used to model the fluid adjacent to the structures and in the channel between the subassemblies; (2) pressure transients in a straight pipe, where the axisymmetric formulation is used to model the fluid in the pipe. These results are compared to experimental results for these problems and compare quite well