Integral experiments play an essential role in the reduction of design uncertainties related to liquid-metal fast breeder reactor neutronics calculations. Spectrum-dependent integral parameters, such as the critical balance, have been the subject of extensive experimental studies in the various critical facility programs of the leading fast reactor programs in view of the extrapolation of the observed results to power reactors. Space-dependent parameters, such as power distribution perturbation and control rod effects, have also been the subject of large experimental programs, but it has been more difficult to find an unambiguous, systematic approach to extrapolate to the reference power reactors with the particular purpose of defining bias factors and uncertainties to be used in design calculations. Different approaches are recalled in the case of spectrum-dependent integral parameters, and some suggestions are made to define a systematic approach for the space-dependent parameters using the existing critical facilities, i.e., reduced-size cores and limited fuel inventories.