iPWR input-deck and scenarios analyses

The HORIZON-EURATOM SAPSAM-SA project, coordinated by ENEA (Italy), was launched in 2022 aiming at filling this gap and at transferring the knowledge and know-how of large LWR to integral PWRs (iPWRs) in view of the European licensing needs with respect to Severe Accident (SA) and Emergency Planning Zone (EPZ). One of the goals of the project is the evaluation of the capabilities of state-of-art European and non- European integral codes to properly predict the key phenomena occurring in postulated SA scenarios in two generic (but representative) iPWRs. Note that such generic reactor concepts include the main iPWR design features considered in the most promising designs in the European market. Having this in mind, a large working activity has been performed in the frame of the WP2 (SCENARIO) by the SASPAM-SA partners aiming at the assessment of the datasets of the most used integral codes in Europe (ASTEC, MELCOR, AC2, EDF-MAAP, and MAAP) for the generic iPWRs considered in the project, the postulation of Design Basis Accident (DBA) and SA scenarios for such systems, and the corresponding calculation campaign. Furthermore, the ANSYS CFX and the containmentFOAM models have been assessed and transient analyses have been performed. The current report focusses on the description of the work activity performed in the WP2, with particular focus on the evaluation of the capabilities of the integral codes employed by the partners to describe the behaviour of the two selected iPWR Designs during both the postulated DBA and SA scenarios. The ASTEC, MELCOR, AC2, EDF-MAAP, and MAAP results of the key figure-of-merits are compared and a quite extensive survey of the capabilities of the code to simulate the most relevant phenomena, e.g., thermal-hydraulics, core degradation, activation of the passive systems, characterizing generic iPWRs designs.