Reactivity Measurement of the Lead Fast Subcritical VENUS-F Reactor Using Beam Interruption Experiments

In order to incinerate minor actinides and thus to reduce the issues linked to nuclear waste management, Accelerator-Driven Systems (ADS) are being under study. An ADS consists in the coupling of a particle accelerator with a sub-critical fast reactor. The on-line reactivity monitoring is a serious issue regarding safety, therefore several methods to estimate the reactivity of such sub-critical systems have to be investigated. Here, we present one method based on the study of the neutron population evolution during beam interruption experiments carried out in the framework of the FREYA FP7 program [1,2] at the GUINEVERE facility, which couples the fast lead sub-critical reactor VENUS-F with the deuteron accelerator GENEPI-3C at SCK-CEN in Mol, Belgium. After describing the facility, the analysis based on point kinetics theory and preliminary results of the reactivity measurements will be presented. Then, spatial effects that are not taken into account by point kinetics theory will be highlighted using MCNP simulations, and correction factors to raw results will be calculated. In the end, final results will be compared to reference reactivity values obtained with the Modified Source Multiplication (MSM) method.