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 Chapter 2 is concerned with radiological safety (radsafe) aspects of the tests. This chapter documents procedures, training, and equipment used to protect participants from potential radiation exposure.

Chapter 3 discusses the general role of personnel in the weapons effects program in CROSSROADS, leading to a discussion of operations for test events in Chapter 4, and in the post-test operations discussed in Chapter 5 and 6.

Chapters 7 through 10 report participation by the Army Ground Forces, Army Air Forces, Navy, and Marine Corps, respectively. Chapter 11 summarizes participation of other government agencies, contractors, and universities. Personnel exposures are discussed in Chapter 12.

NUCLEAR TESTS AND RADIATION EXPOSURES

In general, nuclear testing before 1961 consisted of the unconfined detonation of nuclear devices (usually not weapons) in the atmosphere. The devices might be placed on a platform or a barge on the ocean's surface; emplaced on or slightly beneath the Earth's surface; atop a tower; or supported by a balloon, dropped from an airplane, suspended underwater, or fired from cannon or rocket launchers, CROSSROADS employed two operational weapons: one was dropped from an aircraft and detonated in the air; the other was suspended from a ship and detonated underwater.

In theory, personnel can be exposed either to the radiation emitted at the time of explosion and for about 1 minute thereafter -- usually referred to as initial radiation -- or the radiation emitted later (residual radiation). Initial radiation is part of the violent nuclear explosion process itself.

The neutron component of initial radiation indirectly contributes to the later exposure of personnel. Neutrons are emitted in large numbers by nuclear materials so that they become radioactive. This process, called activation, works on sodium, silicon, calcium, manganese, and iron, as well as other common materials. Activation products thus formed are added to the inventory of the radioactive products produced in the explosion process. The radiation emitted by this inventory more than 1 minute after detonation is referred to as residual radiation.

The potential for personnel exposure to residual radiation was much greater than the potential for exposure to initial radiation. In the nuclear explosion process, fissioning atoms of the heavy elements, uranium and plutonium, split into lighter elements, called fission products, releasing energy. When the uranium and plutonium fission, they produce a variety of fission products. Different fission products have different half-lives. In genial, the lighter fission products have half-lives that are shorter than the mother elements. The residual radiation produced by these products, given their shorter half-lives, is initially quite high. However, over a period of time, the radioactivity diminishes. The decay of the original fission products produces other, lighter fission products that may (or may not) be radioactive themselves. The net result is that initial decay of fission products produces fairly high levels of radioactivity that dissipate over time. While a radioactive fission product

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