As a prolongation of the FP-6 GUINEVERE (Generation of Uninterrupted Intense NEutron pulses at the lead VEnus REactor)
project at the VENUS-F facility at SCK• CEN, the FP-7 FREYA (Fast Reactor Experiments for hYbrid Applications) project was launched in
2011. The FREYA project aims at validating the methodology for subcriticality monitoring of a subcritical core as proposed in the MUSE
experiments conclusions. This is needed for the reactivity monitoring of a powerful ADS (Accelerator Driven System) like MYRRHA.
Experiments are also needed for sub-critical and critical ADS and LFR (Lead Fast Reactor) core characterisation for benchmarking and
licensing purposes. Several levels of sub-criticality of the first subcritical core were measured applying the integral Source Jerk method
and compared to the reference results obtained with the MSM (Modified Source Multiplication) method.