LFR mock-up definition

This work was performed in framework of the EU FP7 project FREYA “Fast Reactor Experiments for hYbrid Applications”. The main goal of the FREYA WP4 Task 4.1 was the definition a critical mock-up representative of the Lead Fast Reactor (LFR) neutronics, to be assembled and characterised in the VENUS-F experimental facility at SCK•CEN in Mol (B). The VENUS-F zero-power reactor results fundamental to support the validation of design tools and methodologies of this new reactor concept, since it allows to perform integral tests and local measurements of representative neutronic parameters. The LFR design chosen as reference is the 300 MWth ALFRED core, developed during the EU FP7 LEADER project. This Technical Report (Deliverable D4.1) summarises the preliminary neutronic analyses carried out to define the LFR critical mock-up in VENUS-F. The study was performed with the ERANOS deterministic code and JEFF3.1 library: many critical core layouts were investigated in order to achieve an “ALFRED representative spectrum”, chosen as leading criterion for the LFR representativeness. The Monte Carlo code MCNP6 was successively utilised to characterise the most promising configurations that foresee a 3x3 assembly matrix at the core boundary called “ALFRED Island”, made of moderating inert assemblies disposed as a chess with the Fuel Assemblies. Afterwards, the LFR critical mock-up in VENUS-F (named CC6 core in FREYA) was defined and assembled at the SCK•CEN, by reaching the first criticality on May 11th, 2015. The main features of the experimental CC6 core are here described, as well as its accurate criticality evaluations with both MCNP6 and ERANOS codes.