AltaRica tools developped at LaBRI have always been dedicated to model- checking thus focusing analysis onto functional aspects of systems. In this re- port we are interested by a problem encountered in safety assessment or diag- nosis domains: the computation of all failure scenarios. This problem consists to determine preponderant sequences of failures of elementary components that lead the system into a critical state. While model-checkers usually look for a counter-example of a good property of the system, here we want to compute all the most significant paths to a bad state. The solution presented in this paper is mainly a mix of existing works taken from the literature; however, in order to be able to treat large models, we have also implemented a preprocessing algorithm that permits to simplify the input model w.r.t. to specified unwanted states.