[en] In sensitivity analysis of the actinide production and depletion in fast reactors, a mathematical method of calculating sensitivity coefficients is improved and simplified by combining the time-dependent generalized perturbation technique with the eigenvalue method. Numerical calculations show that the eigenvalue method is well applicable in solving the nuclide chain equation and its adjoint equation and the cylic chains in the decay scheme of the actinides can be interpreted by means of complex eigenvalues. The sensitivity coefficients of actinide production and depletion in a 1000 MWe fast reactor are strongly dependent on the type of Pu fuel used, i.e. Pu fuel from BWR or Pu fuel from the blanket of FBR. The sensitivity coefficients due to variations of capture cross sections, σsub(n,2n) of ²³⁸U, lambda sub(β) of ²⁴¹Pu and lambda sub(α) of ²⁴²Cm are especially large. Sensitivity analyses for the 1000 MWe fast reactors show that higher priorily should be given to decay constants of ²⁴¹Pu and ²⁴²Cm, capture cross sections of ²³⁷Np, ²⁴¹Am, ²⁴³Am and ²⁴²Pu, and fission cross sections of ²³⁷Np, ²⁴²Pu, ²⁴¹Am and sup(242m)Am. (author)