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. Weather has a huge impact on fallout, wind currents can spread radioactive fallout either over a large area, such as in the case of Castle Bravo, or not.
In regards to nuclear reactions, fission produces more fallout products that fusion. 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.
Watch the fallout video and then answer the questions below:
- Describe the physical appearance of fallout.
- How does fallout spread?
- What was the baby tooth study?
- What particular isotopes does the speaker mention in this video?
- What is the 7-10 rule?
- What mistake does the speaker say when he is discussing different isotopes?
- Why do Americans who lived in 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 required information for your next test.
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 Nuclear Test Ban Treaty. This document would limit where nuclear bombs/devices could be tested. These three countries would no longer perform nuclear trials under water, 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.
During the early ninety's, President George H.W. Bush announced that the United States would no longer perform full scale nuclear tests. Four years later, the 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) sign and ratify the CTBT. In 1996, the United States (President Bill Clinton) quickly signed the CTBT. However, the United State 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, under water, 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.