Basic information about nuclear weapons is presented so that their effects can be meaningfully related to the defensive countermeasures which will be most effective against them. Major topics include: (1) Explosive power of nuclear weapons, (2) Major effects of nuclear explosions, (3) Two basic types of nuclear explosions, (4) Contrast between air and surface bursts, (5) Explosive power and destructiveness of different sizes of nuclear weapons, (6) Characteristics of a nuclear explosion, (7) The nature of fallout and its radiation, (8) Relationship between radiation and illness, (9) Review of the characteristics of fallout, (10) Detecting radiation, (11) Fallout shelters, (12) The National Shelter Program, (13) Types of Shelters, (14) Why a shelter is important, (15) Building your own fallout shelter, and (16) Stocking a shelter. Panel discussions and a test are included. (CK)