on a rocket. On occasion, devices were detonated underwater or burifd in the earth. In theory, personnel could be exposed either by the radiation emitted at the time of explosion and for about 1 minute thereafter -- usuallyf referred to as initial radiation -- or the radiation emitted later radiation). (refidual In practice, however, there was no involuntary direct egpo- sure of personnel to initial radiation during testing. This is partfof the violent nuclear explosion process itself; close enough proximity|for initial radiation exposure would place an observer within the area swept by lethal blast and heat waves. The neutron component of initial radiation did indirectly contrifute to the possibility of personnel exposure. amounts by nuclear weapon explosions. Neutrons are emitted in large They have the property of alt@ring certain nonradioactive materials so that they become radioactive. Tis process, called activation, works on some forms of sodium, silicon, cium, Manganese, and iron, as well as other common materials. The ag@tiva- tion products thus formed were added to the inventory of the radioacfive products formed in the explosion process. The radiation emitted by fhis inventory is referred to as residual radiation. The potential for personnel exposure to residual radiation was mich more of a real problem. In the nuclear explosion process, fissioning atoms of the heavy elements, uranium and plutonium, split into lighter elements, releasing energy. These lighter atoms are themselves radioactive anqg de- cay, forming another generation of descendants from the original fisdions. This process is rapid immediately after the explosion but slows lateg and continues for years at very low levels of radioactivity. The overall radioactivity of all the fission products formed dec a rate that is closely approximated by a rule that states that for e sevenfold increase in time the intensity of the radiation will decredse by a factor of ten. Thus, a radiation rate of 1 roentgen per hour 28 (R/hq) at