In reactor physics, a high degree of accuracy has been achieved regarding the calculation of steady-state reactors but the time dependent problems have not been so deeply investigated. Of course, many point (or space) kinetics programs have been developed, but the data they require are not always available and furthermore, the procedures needed to calculate these kinetic parameters are sometimes not clearly established. A new method, called the "α perturbation", is proposed for the calculation of kinetic parameters. The adjoint fluxes are no longer necessary so that, standard codes devoted to steady state reactors can be used after minor modifications. Moreover, the usual procedures of group condensation and homogenization are discussed regarding the "kinetic information" which must be saved. The EPFL critical assembly CROCUS is proposed as a benchmarking tool and the influence on kinetic parameters of the plutonium recycling in the Beznau II nuclear power plant is analyzed