[en] The highlights of the Transportation System Safety Evaluation (TSSE) Program at Sandia National Laboratories are reviewed and the origins of the program and the relationships to other programs addressing safety concerns are outlined. The areas of current activity in the assessment of possible effects an intentional act or extreme environment could have on nuclear material shipping systems are described. Early information has been obtained on the formation of aerosols, and a significant body of experimentally determined source term data will be available for radiological consequence evaluations