Open string models with Scherk-Schwarz SUSY breaking

We apply the well-known Scherk-Schwarz supersymmetry breaking mechanism in an open string context. We construct a new Z_3\times Z_3^\prime model, containing only D9-branes, and rederive from a more geometric perspective the known Z_6^\prime\times Z_2^\prime model, containing D9, D5 and \bar D 5 branes. We show recent results about the study of quantum instability of these models