A simplified approach for the calculation of tornado depressurization effects on nuclear power plant structures and components is based on a generic computer depressurization analysis for an arbitrary single volume V connected to the atmosphere by an effective vent area A. For a given tornado depressurization transient, the maximum depressurization ΔP of the volume was found to depend on the parameter V/A. The relation between ΔP and V/A can be represented by a single monotonically increasing curve for each of the three design-basis tornadoes described in the U.S. Nuclear Regulatory Commission’s Regulatory Guide 1.76. These curves can be applied to most multiple-volume nuclear power plant structures by considering each volume and its controlling vent area. Where several possible flow areas could be controlling, the maximum value of V/A can be used to estimate a conservative value for ΔP. This simplified approach was shown to yield reasonably conservative results when compared to detailed computer calculations of moderately complex geometries. Treatment of severely complicated geometries, heating and ventilation systems, and multiple blowout panel arrangements were found to be beyond the limitations of the simplified analysis.