The VENUS-F CC6 core: ERANOS neutronic analyses and comparison with experimental data

This work was carried out in the framework of the EU FP7 project FREYA “Fast Reactor Experiments for hYbrid Applications”. The FREYA Work Package 4 (WP4) deals with the definition of a critical mock-up representative of the Lead Fast Reactor (LFR) core design, to be assembled and characterised in the VENUS-F zero power reactor at the SCK•CEN research centre in Mol (B). The LFR design chosen as reference is the 300 MWth Alfred core, developed during the EU FP7 Leader project. In the WP4 Task 4.1 (T4.1) a critical VENUS-F layout called CC6 core - that should reproduce a “LFR representative spectrum” in a specific “Alfred island” at the boundary of the fissile zone - was defined and assembled, by reaching the first criticality on May 11th, 2015. Afterwards, standard core characterisation measurements were performed during the WP4 T4.2 activities. This document summarizes the presentation done by the author in the FREYA WP3/4 meetings on November 12-13th, 2015, at the ANSALDO Nucleare in Genova (I). It reports the main results of a detailed neutronic study carried out with the ERANOS ver. 2.2 deterministic code and the JEFF3.1 data library. In this analysis, the experimental conditions were reproduced by obtaining a significant accuracy in the ERANOS-JEFF3.1 simulations. The main physical quantities investigated were: the core criticality, the control rods calibration and worth, the void reactivity effects, the axial traverses of fission rates (of U235, U238, Pu239 and Np237 nuclides) and their ratio (i.e., spectral indexes). The spectral indexes confirmed that the LFR spectrum was actually almost reproduced in the Alfred island by satisfying one of the main WP4 initial objectives.