32.7 Nuclear Weapons

Nuclear weapons harness the power of atomic reactions to create devastating explosions. Fission bombs split heavy atoms, while fusion bombs combine light atoms. Both types release enormous energy, causing immediate destruction and long-lasting radioactive fallout.

The development of nuclear weapons has shaped global politics since World War II. The arms race, non-proliferation efforts, and disarmament treaties have all played crucial roles in managing the threat of nuclear conflict and promoting peaceful nuclear energy use.

Nuclear Fission and Fusion Weapons

Principles of nuclear bombs

Top images from around the web for Principles of nuclear bombs

• 

  Thermonuclear weapon - Wikipedia View original

  Is this image relevant?

• 

  Nuclear weapon - Wikipedia View original

  Is this image relevant?

• 

  File:Nuclear fission chain reaction.svg - Wikimedia Commons View original

  Is this image relevant?

• 

  Thermonuclear weapon - Wikipedia View original

  Is this image relevant?

• 

  Nuclear weapon - Wikipedia View original

  Is this image relevant?

1 of 3

Top images from around the web for Principles of nuclear bombs

• 

  Thermonuclear weapon - Wikipedia View original

  Is this image relevant?

• 

  Nuclear weapon - Wikipedia View original

  Is this image relevant?

• 

  File:Nuclear fission chain reaction.svg - Wikimedia Commons View original

  Is this image relevant?

• 

  Thermonuclear weapon - Wikipedia View original

  Is this image relevant?

• 

  Nuclear weapon - Wikipedia View original

  Is this image relevant?

1 of 3

• Fission bombs
  • Rely on splitting heavy atomic nuclei (uranium-235, plutonium-239)
  • Initiated by critical mass of fissile material reaches supercritical state
  • Chain reaction rapidly releases large amounts of energy (kilotons of TNT)
  • Requires enrichment of uranium to increase concentration of fissile U-235
• Fusion bombs (thermonuclear weapons)
  • Rely on joining light atomic nuclei (deuterium, tritium)
  • Requires extremely high temperatures and pressures only possible with fission bomb "trigger"
  • Fusion reaction releases even greater energy than fission (megatons of TNT)

Effects of nuclear explosions

• Immediate effects
  • Intense heat and light (thermal radiation) causes fires, burns
  • Powerful blast wave (overpressure, dynamic pressure) crushes structures
  • Prompt ionizing radiation (gamma rays, neutrons) delivers lethal doses
  • Electromagnetic pulse (EMP) disables electronics (power grid, communications)
• Long-term effects
  • Radioactive fallout
    • Fission products and unfissioned material spread by wind
    • Contaminates large areas, persists for years (strontium-90, cesium-137)
  • Environmental damage
    • Destruction of infrastructure and ecosystems
    • Potential nuclear winter from smoke and dust blocking sunlight
  • Human health consequences
    1. Acute radiation sickness causes nausea, hair loss, decreased immunity
    2. Increased risk of cancer (leukemia, thyroid) and genetic mutations
    3. Psychological trauma and social disruption

Nuclear weapons proliferation

• Manhattan Project (1942-1946)
  • U.S.-led WWII effort developed first nuclear weapons
  • Resulted in Trinity test, bombings of Hiroshima and Nagasaki
• Cold War era (1947-1991)
  • U.S.-Soviet nuclear arms race
  • Mutually assured destruction (MAD) deterrence concept
  • U.K., France, China develop nuclear weapons
  • Development of nuclear triad (land-based missiles, submarine-launched missiles, strategic bombers)
• Non-Proliferation Treaty (NPT) (1968)
  • Prevents spread of nuclear weapons, promotes peaceful nuclear energy
  • Recognizes five nuclear-weapon states (U.S., Russia, U.K., France, China)
• Post-Cold War era (1991-present)
  • U.S. and Russian stockpile reductions (START, New START treaties)
  • New nuclear powers emerge
    • India and Pakistan conduct tests (1998)
    • North Korea conducts tests (2006, 2009, 2013, 2016, 2017)
  • Iran and Joint Comprehensive Plan of Action (JCPOA)
    • Agreement limits Iran's nuclear program for sanctions relief
    • U.S. withdraws (2018)
  • Concerns about nuclear terrorism, security of nuclear materials

Nuclear arms control and disarmament efforts

• Nuclear test ban treaties limit nuclear testing (Partial Test Ban Treaty, Comprehensive Nuclear-Test-Ban Treaty)
• Nuclear arms control agreements aim to limit and reduce nuclear arsenals
• Nuclear disarmament efforts seek complete elimination of nuclear weapons
• Challenges include verification, maintaining nuclear deterrence, and addressing nuclear proliferation concerns