The detonation of nuclear bombs is one of the most tragic applications of chemistry in human history– the bombings of Hiroshima and Nagasaki that occurred during the Second World War are stark reminders of the destructive power of nuclear weapons. This article delves into the chemistry behind nuclear bombs and examines the lasting effects of the Hiroshima bombing.
How do Nuclear Explosions happen?
Nuclear Fission:
Nuclear bombs, like the ones dropped on Hiroshima and Nagasaki, operate on the principle of nuclear fission. This process involves splitting a heavy atomic nucleus into smaller nuclei (fission fragments), which release a tremendous amount of energy. “Little Boy”, more commonly known as the ‘Hiroshima bomb’, used the isotope uranium-235 (U-235) as its fissile material. When a neutron strikes a U-235 nucleus, it causes the nucleus to become unstable and split into two smaller nuclei, additional neutrons, and a large amount of energy in heat and gamma radiation.
Chain Reaction:
The neutrons released during the fission of U-235 can strike other U-235 nuclei, causing further fission reactions. This self-sustaining series of reactions is known as a chain reaction and is what causes an atomic explosion.
Criticality
For the chain reaction to occur explosively, the fissile material must reach a critical mass– the minimum amount needed to sustain the chain reaction. This means you need enough U-235 to ensure that neutrons released by fission will strike another nucleus. The bomb design ensures that this critical mass is achieved during detonation.
Energy Release:
The energy released in a nuclear explosion includes the kinetic energy of the fission fragments, electromagnetic radiation, and the kinetic energy of the neutrons. Research shows that the energy released in the Hiroshima explosion was equivalent to approximately 15 kilotons of TNT, causing immense destruction.
Long-Term Effects
Environmental Impact: In the case of Hiroshima, the long-lived isotopes contaminated soil, water, and living organisms– posing long-term health risks.
Genetic Effects: Radiation-induced mutations affected not only the survivors but also their descendants– with slightly elevated rates of genetic disorders observed.
Radiation Exposure: Exposure to ionizing radiation from the fallout led to acute radiation sickness among the survivors. Additionally, long-term exposure increases the incidence of cancers, particularly leukemia.
The chemical processes underlying nuclear explosions, such as the one in Hiroshima, highlight the immense energy contained within atomic nuclei and the profound consequences of releasing that energy. While the long-term effects of the Hiroshima and Nagasaki bombings were catastrophic, the study of these cases has significantly advanced our understanding of nuclear fission and radiation’s impact on human health, as well as the environment. The atrocities of World War II serve as a powerful reminder of the need for responsible management and regulation of nuclear technology.
Reference list
Atomic heritage foundation (2014). Science Behind the Atom Bomb - Nuclear Museum. [online] https://ahf.nuclearmuseum.org/. Available at: https://ahf.nuclearmuseum.org/ahf/history/science-behind-atom-bomb/.
Kids Heiwa Nagasaki. (n.d.). Kids Heiwa Nagasaki. [online] Available at: https://nagasakipeace.jp/en/reference/materials/kids/commentary/genbaku_genri.html.
www.pcf.city.hiroshima.jp. (n.d.). PEACE CULTURE No.78_10 ‘The effects of radiation on the human body’ by Dr. Shinya Matsuura, Director, Research Institute for Radiation Biology and Medicine, Hiroshima University. [online] Available at: https://www.pcf.city.hiroshima.jp/hpcf/heiwabunka/pce078/English/10E.html.
中国新聞ヒロシマ平和メディアセンター. (n.d.). 中国新聞ヒロシマ平和メディアセンター. [online] Available at: https://www.hiroshimapeacemedia.jp.
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