limitations on such activities at the Pacific Proving Ground (PPG). The portion of the experimental program of heaviest DOD participation is emphasized. The chapter concludes with a description of Joint Task Force 7 (JTF 7), the organization that conducted Operation CASTLE, and indicates how the DOD elements within JTF 7 functioned. Chapter 2 is concerned with the radiological safety of the tests. (radsafe) aspects This chapter documents the procedures, training, and equip- ment used to protect participants from the radiation exposure inherent in the test operations. Chapter 3 focuses on the role of the DOD in the experimental program of CASTLE in general, leading to a discussion of the DOD operations for the test events in particular in Chapters 4 and 5. Chapter 4 discusses the BRAVO detonation, and Chapter 5 presents the detonations following BRAVO. Chapters 6 through 9 report participation by the Army, Navy, Air Force, and Marine Corps, respectively. Chapter 10 summarizes the participation of other government agencies and contractors. A listing of participating units and a statistical characterization of their personnel exposures are included in these chapters. The personnel exposures are discussed in Chapter il. Appendixes include: A -- Radsafe-related documents prepared for CASTLE; B -- Glossary of Terms, Abbreviations, Acronyms, and Units; C -- Island Synonyms; and D -- Index of Participating Organizations. NUCLEAR TESTS AND RADIATION EXPOSURES Nuclear testing before 1963 usually 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 surface, placed atop a tower, supported by a balloon, dropped from an airplane, or flown 27