Since long years, IRSN, COGEMA and CEA are pursuing a joint project to develop and to validate the new CRISTAL package, created to improve the criticality safety studies including the burnup credit. The first part of this paper is a presentation of new features and innovations of the V1version of the CRISTAL package. The second part is devoted to illustrate the new possibilities and to describe, through some applications, calculation processes (multi-cell calculations for fuel pins arrays and burnup credit configuration where axial burnup profile, actinides and fissions products are taking into account).