Analysis of aircraft impact to nuclear power plant structures is discussed utilizing a simplified model of a "fictitious nuclear building" to perform analyses using LS-DYNA software, representing the loading: (i) by the Riera force history method and (ii) by modeling the crash by impacting a model of a plane similar to Boeing 747-400 to the structure (i.e., "missile-target interaction method"). Points discussed include: (1) comparison of shock loading within the building as obtained from the Riera force history analysis versus from the missile-target interaction analysis, (2) sensitivity of the results on the assumed Riera force loading area, (3) linear versus nonlinear modeling and (4) on failure criteria. (c) 2006 Elsevier B.V. All rights reserved.