The physical principles of the ERANOS neutronic deterministic code and its application to the LFR and VENUS-F critical cores

This work was carried out in the framework of the EU FP7 project FREYA “Fast Reactor Experiments for hYbrid Applications”. It reports the lecture held by the author during the FREYA WP5 session for training and education on February 22-26th, 2016, at the SCK•CEN Academy for nuclear science and technology in Mol (B). The main goal was to illustrate the potentiality of the ERANOS neutronic deterministic code to PhD students coming from the EU universities. At the same time, this document could be used also in ENEA for students and researchers that may be interested and/or have to be introduced to the utilisation of the code. ERANOS (together with Monte Carlo codes) was widely utilised in the FREYA project: in the design phase of the experiments to be realised in the VENUS-F zero-power reactor (at the Belgian Nuclear Research Centre, SCK•CEN), as well as in the post-processing analyses of the experimental results. Starting from the basic physical principles of the deterministic neutronic analyses, the lecture describes the application of ERANOS to the Lead Fast Reactor (LFR) concept and to a couple of VENUS-F Critical Cores (named CC5 and CC6), assembled and experimentally characterised during FREYA. In particular, the CC6 layout was specifically designed to reproduce locally the typical spectrum of the LFR. The main calculation procedures were briefly shown: the cell / lattice calculations providing multi-group cross-sections of the different reactor zones for full core calculations, which can be carried out with finite differences and variational nodal methods. The experimental measurements on the CC5 and CC6 cores demonstrated the accuracy of the ERANOS results, obtained with JEFF3.1 and ENDF/B6.8 nuclear data libraries. The lecture is focused on the core criticality and spectral index calculations, by pointing out at which extent the CC6 core can reproduce accurately the LFR spectrum.