[en] Earthquakes and postulated pipe breaks in a pressurized water reactor coolant system result in external forces on the reactor fuel system. These applied forces are calculated from a primary coolant system (PCS) analysis using finite element techniques. The application of these forces to the fuel system may result in spacer grid impact loads. An assessment of the sensitivity of spacer grid response loads to variations in the applied forces is necessary to account for the variability in the applied fuel assembly forces due to the finite element approximation and the nonlinear properties of the fuel system. Review of a compilation of available sensitivity data, including that requested by the Nuclear Regulatory Commission from the various fuel vendors, has been accomplished leading to the formulation of conclusions and recommendations concerning fuel system sensitivity to input function variations