Nuclear Physics Notes with PDF

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Nuclear Physics: Particles, Reactions & Fundamental Concepts

1. Sub-atomic Particles & Discoveries

• Meson: Discovered by Hideki Yukawa (Japan, 1935).
• Positron: Discovered by C.D. Anderson and U.F. Hess (1932). It is the antiparticle of the electron.

2. Challenging Established Theories

• Scientists Gunter Nimtz and Alfons Stahlhofen claimed that microwave photons can travel faster than light, challenging Einstein’s theory of relativity.
• Ernest Rutherford doubted that nuclear energy could be harnessed, questioning if Einstein’s mass-energy equivalence would hold.

3. Nuclear Reactions: Fission vs. Fusion

• Nuclear Fission:
  • The process of a heavy atomic nucleus (e.g., Uranium-235) splitting apart into smaller fragments.
  • Used in nuclear reactors and atomic bombs.
• Nuclear Fusion:
  • The process of two lighter atomic nuclei fusing together to form a heavier nucleus.
  • It is the primary source of energy in stars like the Sun.
  • The theory for stellar energy production was explained by H.A. Bethe (1938). Stars obtain energy from fusion and gravitational contraction.
• Clarification: The breaking apart of a nucleus is fission, not fusion.

4. Radioactivity & Properties

• Definition: A nuclear property where an unstable nucleus decays, emitting energy and particles (Alpha, Beta, Gamma rays) to become stable.
• End Product: The ultimate stable end product of uranium decay is Lead.
• Half-Life Calculations:
  • Half-life is the time for half of a radioactive substance to decay.
  • After 1 half-life: 1/2 remains.
  • After 2 half-lives: 1/4 remains.
  • After 3 half-lives: 1/8 remains.
  • After 4 half-lives: 1/16 remains.
  • If 3/4 has decayed (1/4 remains), it corresponds to two half-lives.

5. Radioactive Elements

• Generally, elements with an atomic number greater than 80 are radioactive.
• Exceptions: Technetium and Promethium are radioactive despite lower atomic numbers.
• Non-radioactive example: Zirconium (Z=40) is not radioactive.
• Radioactive examples: Astatine (Z=85), Francium (Z=87), and Tritium.

Nuclear Technology: Reactors, Components & Types

1. Nuclear Reactor Overview

• A device that initiates and controls a self-sustaining nuclear chain reaction.
• Key difference from a bomb: the chain reaction is controlled.
• Uses Uranium-235 or Plutonium-239 as fuel.

2. Reactor Components & Functions

• Moderator:
  • Function: To slow down neutrons produced by fission to sustain a chain reaction.
  • Materials: Heavy Water (D₂O), Ordinary Water, Graphite, Beryllium Oxide.
  • Graphite is used specifically to slow neutrons for U-235 fission.
  • Fast reactors do not use a moderator.
• Control Rods:
  • Function: To manage the fission process and prevent the reaction from going out of control by absorbing neutrons.
  • Materials: Boron, Silver, Indium, and Cadmium.
• Coolants:
  • The Fast Breeder Test Reactor (FBTR) uses Liquid Sodium.

3. Types of Reactors

• Pressurised Heavy Water Reactor (PHWR):
  • Manufactured by India’s Nuclear Power Corporation of India Limited (NPCIL) in 220 MW and 540 MW capacities.
• Breeder Reactor:
  • Produces more fissionable material than it consumes.
  • A fast breeder reactor generates power through fission, not fusion.
• Fusion Reactor (Experimental):
  • The International Thermonuclear Experimental Reactor (ITER) aims to demonstrate fusion power.
  • Location: Cadarache, Southern France.
  • Members: China, EU, India, Japan, South Korea, Russia, USA.
  • Advantage for India: Success would allow the building of fusion reactors for power generation.

4. Supporting Instruments

• Cyclotron: A particle accelerator for charged particles like protons and deuterons.
• Scintillation Counter: Detects radiation by measuring light flashes in a scintillator material.

Nuclear Fuels & Resources

1. Common Nuclear Fuels

• Uranium-235 (U-235): The most widely used fuel. Natural uranium must be enriched for reactor use.
• Plutonium-239 (Pu-239): A primary fuel for power and bombs.
• Thorium: Not a fuel itself but can be converted into fissile Uranium-233. It is more abundant than uranium.

2. Advantages of Thorium

• Abundance: Far more abundant in nature than uranium.
• Efficiency: Generates more energy per unit mass of mined mineral.
• Waste: Produces less harmful, long-lived radioactive waste and fewer weapons-grade materials.

3. Non-Fuel Elements

• Cadmium: Used in control rods, not as fuel.
• Helium, Calcium, Lead, Chromium: Not used as atomic fuels.
• Uranium-238 (U-238): A common but non-fissile isotope, not a primary fuel.

4. Source Minerals

• Monazite is the main source of Thorium.

Nuclear Weapons

1. Principles of Operation

• Atomic Bomb: Based on uncontrolled nuclear fission.
• Hydrogen Bomb (Thermonuclear Bomb): Based on uncontrolled nuclear fusion of hydrogen isotopes (Deuterium and Tritium).

2. Materials and History

• Material: Uses Highly Enriched Uranium (HEU), ~90% U-235.
• Development: The “father” of the hydrogen bomb is Edward Teller.
• First US Test: November 1952 at Eniwetok in the Marshall Islands.

Indian Nuclear Program & Infrastructure

1. Nuclear Tests

• Pokhran-I (1974):
  • Code-named ‘Smiling Buddha’.
  • India’s first nuclear weapon test in Pokhran, Rajasthan.
• Pokhran-II (1998):
  • Code-named ‘Operation Shakti’.
  • Conducted on May 11th and 13th, 1998, involving five tests.

2. Nuclear Doctrine & Policy

• Principles: No First Use, Minimum Credible Deterrence, and a unilateral moratorium on testing.
• NPT Stance: India has refused to sign the Non-Proliferation Treaty (NPT), considering it discriminatory.
• Safeguards: India has a safeguards agreement with the IAEA (ratifying an ‘Additional Protocol’ in 2014), but only civilian reactors using imported uranium are under inspection.

3. Nuclear Power in India

• Status: The fourth-largest source of electricity, contributing about 3% of total generation.
• Operator: All plants are operated by the Nuclear Power Corporation of India Limited (NPCIL).

4. Major Power Plants & Locations

5. Research Institutions & Reactors

• Bhabha Atomic Research Centre (BARC): Primary facility in Trombay, Mumbai.
• Indira Gandhi Centre for Atomic Research (IGCAR): Second-largest facility, located in Kalpakkam, focusing on fast breeder reactors.
• Research Reactors: Dhruva, Purnima, and Cirus are Indian research reactors.
• Fast Breeder Test Reactor (FBTR): At IGCAR, operational since 1985, uses Uranium-Plutonium Carbide fuel.

6. Department of Atomic Energy (DAE) Organizations

• Atomic Minerals Directorate (AMD): Hyderabad
• Heavy Water Board (HWB): Mumbai (First plant in Trombay, Maharashtra)
• Indian Rare Earths Limited (IREL): Mumbai
• Uranium Corporation of India Limited (UCIL): Jaduguda, Jharkhand

7. Other Research Institutes

• Saha Institute of Nuclear Physics: Kolkata.
• Harishchandra Research Institute: Prayagraj, Uttar Pradesh (Mathematics & Theoretical Physics).

International Nuclear Framework

1. Key Organizations

• CERN: The world’s largest particle physics lab, located on the French-Swiss border near Geneva.
• International Panel on Fissile Materials (IPFM): An independent expert group, not an IAEA organ.
• Nuclear Security Summits: Focus on securing nuclear materials, but not held under UN aegis.

2. Nuclear Non-Proliferation Treaty (NPT)

• Objective: Prevent the spread of nuclear weapons (entered force in 1970).
• Nuclear Weapon States (NWS): China, France, Russia, UK, USA (the only five recognized by the treaty).
• Key Non-Members: India, Israel, and Pakistan are not parties to the NPT.

3. Nuclear Suppliers Group (NSG)

• Objective: Control nuclear exports to prevent proliferation. Established in 1974 in response to India’s first nuclear test.
• Membership: 48-member group. Iran is not a member.
• India & NSG: The NSG ban on India was lifted in 2008. France was the first to sign a civil nuclear deal with India afterwards. India seeks membership but has not signed the NPT.

General Science Facts

• Invention: The telephone was invented by Graham Bell.
• Chemistry: Dry ice is solid carbon dioxide.
• Scientific Error (Correction): Enrico Fermi was not solely successful in synthesizing transuranic elements; this is often credited to Glenn T. Seaborg.

Know More About Nuclear Physics:

• Nuclear Physics – Old Year Questions
• Nuclear Physics One Liner Questions & Answers