DNA 1240H-2 fallout (or "“rainout") particles, emitting nuclear radiations due to the edmixed fission products. In the case of an underwater burst, a bubble is formed due to the dissociation and vaporization of the water by the energy of detonation. The gases and steam in the bubble are initially confined within a volume similar to that of the original charge, whereas under normal conditions they would require a much greater volume. Since the bubble is at a high initial pressure, it expands and breaks through the water surface on ite firet expansion, if the burst depth is less thag the bubble radius at maximum expansion. For a deep burst, the dubblesmay go through several expansions, contractions, and upward migrations until it reaches the surface. When the bubble of a shallow burst breaks through the surface, a hollow column of water will be thrown up into the air; plumes of water will be thrown up by deeper bursts. The water will mix with the fission products initially contained in the bubble, and on return to the surface will form a contaminated base surge, or aerosol, that emits gamma radiations. This base surge et first expands radially, but ultimately moves with the wind until it evaporates, disperses, or setties out. * 17.1.3 Scope Two classes of interaction of surface ships with radiation fields are considered: (1) interaction of a shi Ath radiations, involving thermal, neutron, and gamma radiations; toy ‘Triteraction with material particles, involving either the deposition of radioactivity on the ship's weather surfaces, or ingress of activity into the weather envelope via combstion.air and ventilation-air intakes or other openings. The rad- iation fields are due to six classes of radiation: (1) thermal, (2) fire- pall-plume-cloud, (3) transit, (4) deposit, (5) radiation from contaminated water, (6) radiation from contaminated air within the ship. The discussion of thermal radiation, in 17.2, includes the free-field data required to predict damage, the protection from thermal exposure due to shielding by the ship's structure and gear, and the criteria needed to estimate the effects of thermal radiation on combustibles that may be located topside. The asresement of nuclear-radiation effects requires an understanding of the different radiations that emanate from the various radioactive sources resulting from a detonation. Thus, 17,3 discusses the categories into which radiations have been divided, some general characteristics of the various radiations, and sources of weapons test data. The two main categories are fireball-plume-cloud radtations &nd residual radiations. Discussion in 17.4 of the interaction of a ship's structure and gear with fireball-plume-cloud radiation includes discussion of the factors affecting such radiation, a summary of available experimental information, 17-2 owes - wee = es eee ree = we we eee ee