Within the FREYA Project, methods to interpret flux measurements in the VENUS-F core are being studied in order to reconstruct the subcriticality level of the facility. In this work, after the presentation of results obtained with standard techniques such as the Area Method, we introduce an alternative approach to the experimental determination of the reactivity. This method, whose validity has been tested by computational exercises, makes use of general mathematical properties of the point kinetics system of equations and has been recently extended for subcritical system analysis. The evaluation of spatial correction factors is also carried out using deterministic transport evaluations (ERANOS code). The statistical and systematic uncertainty of the results in terms of reactivity is discussed and numerical results are presented