The CRISTAL criticality package. From 2.0 towards 2.1 version

The version 2 of the CRISTAL package, devoted to criticality safety calculations for safety enhancement and criticality risk prevention, was first released in 2014. Since then, four upgrades of its components led to the 2.0.3patch version. The development, verification and validation processes have been carried out in a joint project between the IRSN (Institut de Radioprotection et de Sûrete Nucleaire), the CEA/DES (Direction des EnergieS du Commissariat a l'Energie Atomique et aux Energies Alternatives), in collaboration with Orano group, EDF (Electricite de France) and Framatome. The CRISTAL V2.0.3 experimental validation database contains more than 3100 configurations representing the various configurations encountered in the fuel cycle. The CRISTAL2.0.3 package is available at the OECD Database. In all its 2.0 versions, the CRISTAL package relies on the following extensively validated neutron transport codes and package key components: APOLLO2.8-3.C, MORET 5.B.1 and TRIPOLI-4.8. Each code uses the CEAV5.1.2 library based on the JEFF-3.1.1 nuclear data evaluation, for multigroup and continuous-energy calculations. The link between the CRISTAL calculation codes is ensured by the LATEC workbench that allows users to generate all CRISTAL package input files, to launch calculations and to post-process outputs. The use of validated calculation options with the support of APOLLO2's dedicated procedures ensures high quality results and reproducibility. The purpose of this paper is firstly to present the improvements brought by the latest 2.0.3 version. Secondly, a presentation of the major upgrades of the future 2.1 version with a specific focus on experimental validation, new calculation tools, nuclear data libraries and functionalities, is made. (author)