Accident phenomena and offsite consequences of severe reactor accidents have been the subjects of considerable research over the last several decades by the U.S. Nuclear Regulatory Commission (NRC). As a consequence of this research focus, analyses of severe accidents at nuclear power reactors are more detailed, integrated, and realistic than at any time in the past. A desire to leverage this capability to address conservative aspects of previous reactor accident analyses was a major motivating factor in the genesis of the State-of-the-Art Reactor Consequence Analyses (SOARCA) project. By applying modern analysis tools and techniques, the SOARCA project developed a body of knowledge regarding the realistic outcomes of select severe nuclear reactor accidents.