[en] This paper deals with recent development on a finite element technique in order to compute two phase flow problems encountered in nuclear reactors. In the first part, the choice of a finite element method (F.E.M.) is discussed in order to compute 2 or 3 D problems and the homogeneous physical model is presented. Secondly, the kind of finite elements used in the computation is given with their consistency proprieties. After, we investigate a method of discretization for the non-linear set of equations : so, we study the linear stability of this system which leads to a semi-implicit time integration. We present, at least, the advantages by using this technique for computing multidimensional two phase flow problems