Possible working range of the MYRRHA core and basic neutronic parameters for safety analyses

This work was carried out in the framework of the EU FP7 project MAXSIMA “Methodology, Analysis and eXperiments for the Safety In MYRRHA Assessment”. The MAXSIMA WP2 deals with the safety analyses to support the licensing of MYRRHA (the LBE-cooled multi-purpose irradiation facility planned to be built at the SCK-CEN research center in Mol, Belgium), in which Task T2.1 is devoted to the neutronic and shielding analyses in support of TH safety studies (T2.2 and T2.3). The neutronic parameters (needed for TH transient analyses) were evaluated through the analysis of envelope cases - minimum and maximum core layouts in both critical and sub-critical operational modes - yielding the possible working range of the MYRRHA core. This report (Deliverable D2.1) summarises the main results of the T2.1 neutronic analyses, carried out by deterministic and Monte Carlo methods (i.e. ERANOS and MCNPX codes). Besides the main core features in operating conditions (e.g. keff, peak factors), the deterministic characterisation includes the evaluation of reactivity feedbacks / coefficients (with temperature) and of the impact of accidental (and abnormal) events on the core reactivity.