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6.8: Fallout and Weapons Testing

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    Operation Crossroads

    Near the end of World War II, the United States acquired many islands in the South Pacific. Here, numerous nuclear gadgets and bombs were tested in various scenarios. The first round of testing was performed in the summer of 1946 on the Bikini Atoll located in the Marshall Islands. This event was code-named "Operation Crossroads" and it included the testing of two different fission bombs which each yielded approximately 23 kilotons of power. The Able device was dropped on July 1, 1946, by airplane over water containing a variety of warships. On July 25, 1946, the Baker device was detonated 90 feet underwater. Both tests were done to understand how nuclear weapons affect seafaring vessels.

    Figure \(\PageIndex{1}\): Baker Nuclear Test over the Bikini Atoll.

    In 1976, filmmaker Bruce Connor along with composers Patrick Gleeson and Terry Riley produced a 34-minute film entitled, "Operation Crossroads." In this short movie, viewers can see the immense power of the Baker Test. Both the Museum of Modern Art and the Whitney Museum in New York City have shown Operation Crossroads in their exhibits.

    Video \(\PageIndex{1}\): Crossroads is a 1976 short film directed by Bruce Conner. It features 36 minutes of extreme slow-motion replays of the July 25, 1946 Operation Crossroads Baker underwater nuclear test at Bikini Atoll in the Pacific.

    On July 26, 2016, the American National Security Archives released extensive footage of nuclear bomb testing at the Bikini Atoll. Click this link to access any of these 15 declassified film clips.


    Fallout refers to the radioactive material that "falls out" of the atmosphere after a nuclear explosion (reactor or bomb). It consists of dust and radioactive particles that can contaminate an area with radioactivity and pose a huge health hazard to biological organisms. It can contaminate the animal food chain which can have drastic effects on the affected region. The weather has a huge impact on the fallout, wind currents can spread radioactive fallout either over a large area, such as in the case of Castle Bravo, or not.

    Figure \(\PageIndex{2}\): The 450 km (280 mi) fallout plume from 15 Mt shot Castle Bravo, 1954. (Pubic Domain; United States Department of Energy via Wikipedia)

    altIn regards to nuclear reactions, fission produces more fallout products than fusion. The intense heat of the latter type of reactions reduces the amount and type of radioisotopes produced. Although more powerful, fusion is a "cleaner" type of nuclear reaction. By increasing the fission component of a fusion weapon, bombs can be designed to generate more fallout products. Of the different types of isotopes that fission produces, the most worrisome are Sr-90, Cs-137, and I-131. The first of these isotopes has a half-life of 28.8 years and decays by gamma and beta emission. Once ingested or inhaled, Sr-90 deposits in teeth, bone, and bone marrow. Sr-90 exposure can lead to bone cancer and/or leukemia. Cs-137 (t1/2 = 30.17 years) emits beta and gamma radiation. This ionizing radiation deposits in soft tissues of the body. In addition, this particular radioisotope is water-soluble and can easily contaminant food and water supplies. I-131 had a half-life over 8.1 days and undergoes gamma/beta decay. Once this fallout product enters the body, it attacks the thyroid gland. Extensive damage could affect heart rate, blood pressure, body temperature, and childhood growth. In addition, I-131 exposure could result in thyroid cancer.

    Example \(\PageIndex{1}\):

    Watch the fallout video and then answer the questions below:

    1. Describe the physical appearance of fallout.
    2. How does fallout spread?
    3. What was the baby tooth study?
    4. What particular isotopes does the speaker mention in this video?
    5. What is the 7-10 rule?
    6. What mistake does the speaker say when he is discussing different isotopes?
    7. Why do Americans who lived in the country from 1945-1963 have more I-131 in their bodies?


    Today, there are medications that can be dispensed to help with fallout exposure. On the (Center for Disease Control)'s link, there are four different substances described. Research one of these substances by evaluating how they protect the body and what particular isotope the antidote can counteract. In addition, be aware of one group of individuals who cannot take this medication. This information is the required information for your next test.

    Figure \(\PageIndex{3}\): Dutch Artist, Vincent Van Gogh (1853-1890), used Prussian Blue as one of the signature blues in his Starry Night (1889). Prussian Blue is also used as an antidote for radioactive thallium and cesium. (Publci Domain; Vincent van Gogh via Wikipedia)

    Limiting Nuclear Weapon Testing

    On August 5, 1963, the leaders of the United States (President John F. Kennedy), the Soviet Union, and the United Kingdom signed the Partial Nuclear Test Ban Treaty. This document would limit where nuclear bombs/devices could be tested. These three countries would no longer perform nuclear trials underwater, in the atmosphere, or in outer space. This treaty would allow countries to remain testing underground with certain limits. Also, these countries would attempt to move towards disarmament. Reducing nuclear weapons and testing would allow the environment to recover from decades of contamination.

    Figure \(\PageIndex{3}\): President John F. Kennedy signing the Partial Nuclear Test Ban Treaty in 1963. Image is taken from

    During the early nineties, President George H.W. Bush announced that the United States would no longer perform full-scale nuclear tests. Four years later, the United Nations General Assembly adopted the Comprehensive Test Ban Treaty. This agreement (known as the CTBT) would halt nuclear bomb/device testing entirely. To go in effect, the United Nations required forty-four of the current nuclear states (those with nuclear capabilities) to sign and ratify the CTBT. In 1996, the United States (President Bill Clinton) quickly signed the CTBT. However, the United States Senate refused to provide support and the United States has not ratified it. There are several countries that have not signed and refused to ratify the CTBT. These countries include North Korea, India, and Pakistan. Others have signed but not ratified the treaty: China, Israel, Iran, Egypt, and the United States. For a comprehensive list of countries, click on this link.

    From 1945 to 1992, the United States has tested approximately 1,054 nuclear bombs and devices. Of this amount, 216 of these tests were performed in the atmosphere, underwater, and in outer space. The majority of these tests detonated in the Nevada Test Site, New Mexico Test Site, and the Marshall Islands (South Pacific).

    Other countries have done significant nuclear testing as well. Looking at the figure below once can visualize how many nuclear bombs/devices have been detonated over a fifty-year period. This link shows all (not just the United States') nuclear test sites.

    Figure \(\PageIndex{4}\): Image taken from:

    Contributors and Attributions

    • Frank A. Settle (Washington and Lee University)

    • Complete Bibliography on Radiation from the Alsos Digital Library for Nuclear Issues

    This page titled 6.8: Fallout and Weapons Testing is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Elizabeth Gordon.

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