The code currently used by NRC's emergency operations center for making dose projections for atmospheric releases during radiological emergencies is RASCAL version 3.0.5 (Radiological Assessment System for Consequence AnaLysis). This code was developed by NRC. The first version was created about 20 years ago. Since then the code has been undergoing continual improvement to expand its capabilities and to update the models used in its calculations. This report describes the models and calculational methods used in RASCAL 3.0.5. This report updates and supercedes the information in NUREG-1741, "RASCAL 3.0: Description of Models and Methods," 2001.