Radioactive Fallout (1964)

a nuclear burst is frequently thought of as totally apart from Conventional Weapons but what is it that sets it apart heat null the degree of heat is greater but there is a heat factor in Conventional Weapons too blast again much greater in degree but also found in Conventional Weapons the one totally different factor in a nuclear burst is radioactive fallout the effects from Fallout of a nuclear explosion range far beyond the effects of heat and blast the hazards from Fallout can extend for hundreds of miles from ground zero and continue for days or weeks it is the story of radioactive pullout resulting from a nuclear surface burst that this film will tell [Music] within the fireball of a nuclear burst the temperature and pressure are so high that everything in the fireball is vaporized including the radioactive beta and gamma emitting fishing products in a surface burst large quantities of dirt and debris are drawn into the cloud at Early times this debris mixes with a vaporized products during the initial phases of cloud formation and growth as cool air is drawn into the Fireball and much of the heat energy is emitted as thermal radiation the cloud cools when sufficient cooling has occurred the vaporized radioactive fishing products shown here as Hollow circles begin to condense on the dirt and debris particles in the cloud as this condensation occurs Fallout particles are formed some of the particles are the size of grains of sand others are microscopic all of them are not radioactive but those that are emit nuclear radiation it is exposure to this penetrating radiation that can cause sickness and even death these Fallout particles inhabit the entire Cloud a cloud that may Tower to Heights of over 100,000 ft there are variations in the size shape Radioactive content and final height that the particles reach but for all surface bursts some generalities do apply about 10% of the radioactive materials are in the stem the remaining 90% are in the cloud proper the mushroom head those particles at the top of the cloud contribute to delayed Fallout they remain in the stratosphere for long periods of time and disperse over much of the world however it is the early Fallout that produces the major survival problem this Fallout contains most of the radioactive particles produced by the bomb these particles fall to Earth up to several hundred miles from ground zero in dangerously heavy concentrations one of the factors that determines how the particles will deposit on the ground is the size shape and density of the particles themselves the larger heavier particles will deposit close to ground zero on the other hand the lighter smaller particles disperse more widely they may take hours to descend and in that time winds may carry them hundreds of miles from Ground Zero Fallout deposition is also affected by the altitude of the particles in the cloud although the smaller particles are found predominantly at the top of the cloud and the larger ones predominantly at the base there are no strict boundary lines large and small particles do occur at all altitudes within the cloud all factors being equal the higher particles will be carried further and so will disperse more widely than the lower ones another important factor determining the area covered by appreciable full out as well as its distribution within that area is the integrated wind pattern from the top of the cloud to the ground here we're using just a slice of the mushroom cloud for illustration direction and speed of the wind at Cloud level will influence the motion and extent of the cloud itself the winds at lower altitudes can cause the Fallout particles to drift one way then another while they descend to Earth under actual nuclear detonation conditions all of the factors we've mentioned interrelate to produce a highly irregular pattern areas of heavy Fallout may appear some distance from Ground Zero just as light Fallout zones may appear in close precipitation rain snow or hail will bring down an increased number of Fallout particles as the cloud passes through it causing hot spots which are areas of much higher dose rates than in the immediate surroundings additional patterns from other blasts May well move in and overlap as shown in the highlighted portions here adding still further to the complexity this irregular pattern is difficult to reproduce in training exercises consequently styliz symmetrical Fallout patterns are commonly used for illustration purposes even though they're rarely found after actual nuclear burst these stylized patterns are useful in showing general principles or for estimating the overall effect of Fallout from a large scale attack we have traced Fallout from its formation to its silent deposition on the ground this is the first step in understanding the problems associated with Fallout and so will better enable us to take protective measures for our survival