Alpha Decay and Nuclear Fission

Alpha Decay

• Radioactive decay where unstable nucleus emits an alpha particle
• Alpha particle consists of two protons and two neutrons
• Results in a new element with a reduced atomic number
• Alpha particles are positively charged
• Can be stopped by paper or skin
• Decreases the mass number of the original atom by four and atomic number by two
• Uranium-238 and Radium-226 are common alpha-emitting isotopes
• Typically occurs in heavy elements seeking stability by reducing mass and atomic number

Nuclear Fission

• The process where a heavy atomic nucleus splits into two or more lighter nuclei
• Releases significant energy and neutrons, which can induce additional reactions
• Uranium-235 and plutonium-239 are common fissile materials
• Fission reactions are used in nuclear reactors for energy production
• If uncontrolled, the process can lead to a chain reaction
• Chain reaction can cause nuclear explosions
• Handling fissionable materials requires safety measures to prevent nuclear accidents

Nuclear Fusion

• The process where two light atomic nuclei combine to form a heavier nucleus
• Releases tremendous energy
• Powers stars like the Sun
• Has potential for sustainable energy on Earth
• Requires extremely high temperature and pressure to overcome electrostatic repulsion
• Deuterium and tritium are common isotopes used, often yielding helium and a neutron
• Fusion has abundant fuel supply, minimal long-lived radioactive waste (compared to fission)
• Research focuses on controlled fusion in reactors like tokamaks and inertial confinement

Nuclear Radiation

• Emission of energy and particles from unstable atomic nuclei
• Includes alpha particles, beta particles, and gamma rays
• Alpha particles: two protons and two neutrons, low penetration, stopped by paper
• Beta particles: high-energy electrons or positrons, more penetrating than alpha particles, stopped by plastic or glass
• Gamma rays: electromagnetic radiation with high energy and deep penetration, requires lead or concrete shielding
• Radiation exposure measured in sieverts (Sv), indicating biological effects on human tissue

Strong Nuclear Force

• One of the four fundamental forces
• Holds protons and neutrons together in atomic nuclei
• Overcomes electromagnetic repulsion between charged particles
• Operates at very short ranges, about 1 femtometer (10^-15 meters)
• Gluons mediate the force between quarks within protons and neutrons
• Strength increases at shorter distances
• Much stronger than electromagnetic and gravitational forces, acts at subatomic scales

Types of Radiation

• Energy emitted from unstable atomic nuclei
• Classified into alpha, beta, and gamma radiation
• Alpha radiation: helium nuclei, heavily charged, low penetration, stopped by paper/skin
• Beta radiation: high-energy electrons/positrons, more penetration than alpha, stopped by plastic
• Gamma radiation: high-energy electromagnetic, highly penetrating, requires lead/concrete
• Radiation can be natural (cosmic, terrestrial) or artificial (nuclear reactors, medical applications)

Alpha Particles

• Positively charged, consist of two protons and two neutrons
• Emitted during the decay of heavy atomic nuclei
• Low penetration power, stopped by paper or skin
• Carry a +2 charge
• Strongly ionizing, can cause significant damage to biological tissues
• Alpha decay occurs often in heavy elements
• Not typically dangerous unless ingested or inhaled

Beta Particles

• High-energy, high-speed electrons or positrons
• Emitted during radioactive decay
• Classified as beta-minus (electrons) or beta-plus (positrons)
• More penetrating than alpha particles, less than gamma rays
• Results in transformation of a neutron into a proton (or vice versa)
• Can have a negative or positive charge

Containment Structure

• Robust, engineered barrier
• Prevents release of radioactive materials during accidents or system failures
• Made of reinforced concrete and steel for strength and durability
• Designed to withstand earthquakes, floods, and explosions
• Often includes multiple layers like pressure vessels and domes
• Regular inspections and maintenance are crucial

Fuel Rods

• Cylindrical tubes containing nuclear fuel, typically enriched uranium or plutonium pellets
• Used in reactors to sustain nuclear fission reactions
• Arrangement in reactor core influences neutronic behavior and heat generation
• Made of zirconium alloys to withstand high temperatures and corrosion
• Spent fuel rods become highly radioactive
• Require secure storage and management for thousands of years
• Regular inspections and maintenance needed to ensure integrity and safety

Gamma Rays

• High-energy electromagnetic waves
• Emitted during radioactive decay
• Have the shortest wavelength and highest frequency
• Can penetrate most materials
• Require dense shielding like lead or thick concrete
• Used in cancer radiotherapy to target and destroy malignant cells
• Detected by Geiger counters and scintillation detectors

Ionizing Radiation

• Particles/electromagnetic waves with sufficient energy to detach electrons from atoms, creating ions
• Can damage biological tissues, leading to potential health risks
• Includes alpha particles, beta particles, gamma rays, and X-rays
• Exposure measured in sieverts or rems
• Shielding and monitoring devices used in areas with ionizing radiation sources

Plutonium-239

• Radioactive isotope with a half-life of 24,100 years
• Used as fuel in nuclear reactors and atomic bombs
• Produced from uranium-238 through neutron capture and subsequent beta decay
• Emits alpha particles, posing health risks if ingested or inhaled
• Critical for breeder reactors to enhance nuclear fuel sustainability
• Its critical mass 10 kg in a spherical shape

Uranium-235

• Fissile isotope of uranium that sustains nuclear chain reactions
• Crucial for reactors and nuclear weapons
• Occurs at about 0.72% in uranium, can be enriched for reactor use
• Fission releases energy and neutrons that enable further reactions
• Used as fuel in pressurized and boiling water reactors
• First used in the 'Little Boy' bomb dropped on Hiroshima