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3 An Overview of the U.S. Nuclear Weapons Testing Program From the start of the Trinity project in 1945 until the signing of the Limited Nuclear Test Ban Treaty in 1963, the United States conducted 19 operations (test series) involving tests of atmospheric nuclear weapons. In the course of these operations, more than 230 detonations (shots) were carried out, primarily at the Nevada Test Site and the Pacific Proving Ground (Gladeck and Johnson, 1996~.~ It is estimated that more than 200,000 Department of Defense (DoD) personnel, both military and civilian, participated in these tests (DTRA, 1999~. Responsibility for the planning and conduct of U.S. atmospheric nuclear weapons tests was shared by the DoD and the Atomic Energy Commission (AEC) (DNA, 1981), the successor to the Manhattan Engineer District (Gladeck and Johnson, 1996) and the predecessor of the Nuclear Regulatory Commission. The AEC was responsible for the development of nuclear technology, whereas the DoD was responsible for incorporating this technology into the United States military defense program (Harris et al., 1981~. DoD military personnel (Army, Navy, Air Force, and Marine Corps members), as well as civilian employees and contractors of the DoD and AEC, all participated in nuclear weapons tests (DNA, 1981~. The types of personnel present and the nature of their involve- ment in these tests varied by shot and by series. In general, the roles and functions of DoD personnel present at test detona- tions were to witness the nuclear weapon test event, to participate in military exercises and perform tactical functions or support services, and to set up vari- ous scientific experiments and collect post-shot data. Dose limits in place during the tests functioned as safety guidelines rather than as restrictive cut-points. iThe Pacific Proving Ground tests took place on the Enewetak and Bikini Atolls, southwest of Hawaii. 13

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14 THE FIVE SERIES STUDY These DoD-prescribed exposure limits varied, but generally allowed maximum exposures of 3 to 5 rem (30 to 50 millisievert [mSv]) "per test or series" (Gladeck and Johnson, 1996, p. 20~. The Defense Nuclear Agency estimates that the average dose received by a participant was about 6 mSv (DTRA, 1999)- approximately twice as large as the average annual natural background dose re- ceived by a person living in the United States (NCRP, 1987) and more than 16 times lower than the threshold for deterministic effects (ICRP, 1984~. It is esti- mated that less than 1 percent of all test participants received doses in excess of 50 mSv (DTRA, 1999), the current annual dose limit for radiation workers (CFR, 1 99 1; Gladeck and Johnson, 1 996~. Operations GREENHOUSE, UPSHOT-KNOTHOLE, CASTLE, RED- WING, and PLUMBBOB represent a subset of the 19 total nuclear weapons test series. These five series included 62 shots and involved approximately 68,168 military participants (DSWA, 19974. The subset of five series was selected by the Medical Follow-up Agency's Subcommittee on Exposure at Tests of Nuclear Weapons as the focus of the 1985 National Research Council report Mortality of Nuclear Weapons Test Participants (Robinette et al., 1985~. These particular series were chosen to include similar numbers of Nevada Test Site and Pacific Proving Ground participants. The availability and quality of both personnel and radiation dosimetry records were also considered in the selection of series for study (Robinette et al., 19854. Three of the five series were noted in the 1985 National Research Council report as including shots in which unexpected poten- tial for radiation exposure arose during the test event (Robinette et al., 1985~. PLUMBBOB, the series that includes Shot SMOKY, the exposure that was first identified as associated with leukemia, was also among the series selected for study. The present investigation is intended to supersede the 1985 study (see Chapter 1) and focuses, therefore, on the same subset of test series. GREENHOUSE Operation GREENHOUSE, the fourth postwar atmospheric nuclear weap- ons test series, was conducted in April and May of 1951 at the Pacific Proving Ground. GREENHOUSE consisted of four shots, all detonated on towers. Shots ranged in yield from 45.5 to 225 kilotons (kt) (Gladeck and Johnson, 1996~. Three of the four detonations resulted in significant downwind fallout that affected nearby ships and island base camps during the detonation and fallout periods (Berkhouse et al., 1983; Gladeck and Johnson, 19964. The DNA reports that fallout exposures were greater for island-based personnel than for shipboard personnel because water washdown systems, shielding, and decontamination procedures on board ships served to mitigate contamination (Berkhouse et al., 1983; DNA, 1981; Gladeck and Johnson, 1996~. Approximately 9,528 personnel participated in this series (DSWA, 19974.2 Navy personnel were present at 2Estimates presented in this overview reflect military personnel only.

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OVER VIE WOF U.S. NUCLEAR WEAPONS TESTING PROGRAM 15 GREENHOUSE shots in the largest number. Air Force and Army personnel were represented in smaller numbers, with few Marine Corps participants (DSWA, 1997~. UPSHOT-KNOTHOLE Operation UPSHOT-KNOTHOLE was conducted between March and June of 1953 at the Nevada Test Site. During UPSHOT-KNOTHOLE, 11 nuclear devices were detonated one device fired from a 280-millimeter cannon, three air drops, and seven tower shots. Shots in this series ranged in yield from 0.2 to 61 kt (Ponton et al., 19824. Nine of the tests in this series had yields in excess of 10 kt (Gladeck and Johnson, 1996~. During Shot BADGER, one of the tower detonations, wind shifts resulted in the exposure of members of the Marine Corps' First Battalion to higher than approved doses (DNA, 19829. Also, some of the military personnel present at shots in this series were exposed to neutron radiation while at positions rela- tively close to ground zero. Johnson and colleagues (1986) stated that "Edjuring Operations UPSHOT-KNOTHOLE (1953), TEAPOT (1955), and PLUMBBOB (1957), all at the Nevada Test Site, about 10,000 military observers and maneu- vers troops were exposed to neutron radiation while observing tests from for- ward locations in the shot areas" (p. 219. Neutron doses for all but 544 partici- pants were calculated to be less than 5 mSv (Gladeck and Johnson, 1996; Johnson et al., 19864. Altogether, approximately 18,473 personnel participated in shots in the UPSHOT-KNOTHOLE series (DSWA, 1997~. Most participants were members of the Army, but small contingents of Marine Corps and Air Force personnel, and an even smaller number of Navy personnel, were also pre- sent (DSWA, 19979. CASTLE The CASTLE series was conducted to test large-yield thermonuclear de- vices. Operation CASTLE took place at the Pacific Proving Ground in March through May of 1954 and consisted of six test detonations, ranging in magnitude from 110 kt to 15 megatons (Mt). Shot BRAVO, the first detonation, signifi- cantly exceeded its expected yield and "was the largest device ever detonated by the U.S. Government as part of atmospheric nuclear weapons testing" (Gladeck and Johnson, 19964. Unexpectedly heavy fallout affected a small number of U.S. military personnel and the Japanese fishing boat Fortunate Dragon No. 5 (Mar- tin and Rowland, 1982~. "Shot BRAVO was without question the worst single incident of fallout exposures in all the U.S. atmospheric testing program" (Mar- tin and Rowland, 1982, p. 235~. No other test in the series resulted in significant unexpected exposures (DNA, 1982; Martin and Rowland, 19829. Most of the estimated 15,685 personnel (DSWA, 1997) participating in the CASTLE tests were members of the Navy. Sizable numbers of Air Force and

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16 THE FIVE SERIES STUDY ArTny personnel were also present, as were a comparatively small number of Marines (DSWA, 1997). REDWING REDWING was a 17-detonation nuclear weapons test series conducted at the Pacific Proving Ground in the spring and summer of 1956. Like those in the CASTLE series, these detonations were conducted primarily as tests of thermo- nuclear devices (Bruce-Henderson et al., 1982~. REDWING tests included six barge shots, three surface shots, six tower shots, and two air drops, ranging in magnitude from 13.7 kt to 5 Mt. Because of the complications associated with Shot BRAVO in the CASTLE series, additional safety precautions were taken (Martin and Rowland, 1982), and dosimeters were issued to all participants in Operation REDWING (Bruce- Henderson et al., 1982~. This operation "ran smoothly except for two incidents" (Bruce-Henderson et al., 1982, p. 3~. One of the airdrops, Shot CHEROKEE, detonated considerably off target although no unexpected radiation exposures occurred as a result (Bruce-Henderson et al., 19829. Shot TEWA, fired at Bikini Atoll, resulted in fallout on the Enewetak base camp. Personnel remaining in the camp at the time of the test were unexpectedly exposed to ionizing radiation (Bruce-Henderson et al., 1982~. Approximately 12,923 personnel participated in the REDWING series (DSWA, 1997~. Navy personnel constituted the largest group of armed forces personnel present during the test series. Army and Air Force, and to a lesser extent Marine Corps, personnel were also present (DSWA, 1997~. PLUMBBOB Operation PLUMBBOB was conducted between May and October 1957 at the Nevada Test Site. PLUMBBOB consisted of 30 test events, including 24 nuclear detonations and 6 safety tests. Detonations ranged in yield from slight (safety tests) to 44 kt. Safety tests were designed to ensure the stability of the explosive components of nuclear devices prior to transport and stockpiling (Har- risetal.,1981~. The opportunity for radiation exposure among participants in this test series was diffuse since "it was customary to offer personnel not assigned onsite duties (e.g., finance) the opportunity to watch a shot in the test series which they sup- ported" (Harris et al., 1981~. As with shots in the UPSHOT-KNOTHOLE series, some of the military observers and maneuvers personnel present at PLUMBBOB were exposed to neutron radiation while at positions relatively close to ground zero; however, radiation exposures of unexpected location or magnitude are not specifically noted for shots in this series. Concern regarding leukemia incidence

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OVER VIE WOF U.S. NUCLEAR WEAPONS TESTING PROGRAM 17 among participants at Shot SMOKY in this series gave rise to studies of the health consequences of participation in atmospheric nuclear weapons tests. Most of the estimated 11,559 (DSWA, 1997) PLUMBBOB participants were Army personnel. Members of the Marine Corps and Air Force participated in large numbers. A small number of Navy personnel were also involved in PLUMBBOB tests (DSWA, 1997~. ESTIMATES OF EXTERNAL DOSES Although we did not use NTPR dose estimates in this study's analyses, we present in Table 3-1 (see page 18) the official published NTPR summary exter- nal dose data for each of the five series we studied for reference.

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