Spanish contribution in the design of the ASTRID reactor inside the ESNII+ Project

Significant efforts are being devoted in order to boost R&D on advanced nuclear reactors due to their sustainability and improved safety characteristics. Numerous benchmarks, whose aim is to assess and improve the methodologies and computer codes used to calculate neutronic parameters and reactivity coefficients in SFRs, have been set up. Amongst them, as a contribution to the ESNII+ Project, a benchmark exercise evaluating the safety coefficients of an ASTRID-like reactor was performed. The objective of this work is to assess the safety coefficients of an ASTRID-like reactor in order to identify the capabilities and possible limitations of the methodologies, codes and nuclear data employed in the calculations. Furthermore, these results will be compared and validated against the results of other partners. The ASTRID-like core was modelled at operating conditions with the SCALE system and MCNP code, using ENDF/B-VII.0 and JEFF-3.1.1 libraries respectively. Core multiplication factor, power peaking factors, kinetic parameters, reactivity feedback coefficients and control system worth were calculated. Nine voiding scenarios were studied, confirming the negative reactivity effect from the total voiding of the core. A comparison between the participants in the benchmark was carried out, providing an evaluation of the performance of the current state-of-the art neutronic codes for Gen-IV SFR reactor safety analyses