[en] The worldwide renewed interest in Accelerator Driven Systems (ADS) has promoted the further development of several related research domains. One of the most important aspects that has to be addressed is the safe operation of future ADS. Within this context, expert knowledge regarding the stability and control of reactor power levels in ADS is essential. The dynamic behaviour of the neutron population in a reactor core is determined by its dynamic parameters, among which the effective delayed neutron fraction beta_eff and the mean neutron lifetime l are the most important ones. An absolute measurement technique for the simultaneous determination of these parameters in a subcritical facility loaded with MOX-fuel and driven by an external/intrinsic source is presented. This method is based on the combination of two well-known techniques: the Rossi-alpha method for reactor noise fluctuation analysis at stationary subcritical level and the Prompt Jump analysis of the time evolution after source withdrawal. The combination of both techniques, called RAPJA (Rossi-Alpha and Prompt Jump Analysis) allows to determine the reactivity together with the dynamic parameters beta_eff and l without relying on code calculations to provide absolute information on additional parameters. It is shown that the RAPJA-technique is applicable for the determination of the dynamic parameters in a subcritical facility loaded with MOX-fuel