The Department of Defense has placed nuclear blast and thermal survivability criteria on a number of tactical nuclear and conventional weapon systems. The types of damage mechanisms important in nuclear blast and thermal survivability are discussed. The current technology for performing nuclear blast and thermal loading simulations is reviewed. The current design of Thermal Radiation Source units and their limitations are discussed. The problems of designing a large scale nuclear blast simulator are discussed. Two possible designs for a simulator to test full scale vehicles to nuclear blast and thermal effects are outlined.