Information to support the LFR ALFRED FA/core definition on VENUS: preliminary spectra analyses (with the ERANOS deterministic code)

This work was carried out in the framework of the EU FP7 project FREYA “Fast Reactor Experiments for hYbrid Applications”. The FREYA WP4 deals with the definition a critical mock-up representative of the LFR core design, to be assembled and characterised in the VENUS-F experimental facility at SCK•CEN in Mol (B). The LFR design chosen as reference is the 300 MWth Alfred core, developed during the EU FP7 Leader project. This document summarizes the presentation done by the author in the FREYA WP4 Extended kick-off meeting on January 27th, 2015, at the SCK•CEN Headquarters in Brussels (B). A neutronic analysis was performed to verify whether the VENUS-F CC5 core (defined for the WP3 activities) can provide an “Alfred representative spectrum”, chosen as leading criterion for the LFR representativeness (to support the validation of design tools and methodologies for this new reactor concept, as neutron transport codes and data libraries). The study, carried out with the ERANOS ver. 2.2 deterministic code and JEFF3.1 data, pointed out that the CC5 core spectrum results decisively harder than the aimed Alfred ones. Since the licensing of a different Fuel Assembly (FA) was not allowed in the stringent FREYA work plan, three different strategies were investigated in order to reproduce, at least locally, an Alfred representative spectrum. The ERANOS analyses indicated that the third solution, foreseeing the insertion of some moderating inert assemblies (made of Al2O3 rodlets) disposed as a chess with the FA, can satisfy this requirement and fulfil most of the WP4 objectives.