Nuclear Reactors and Radioactivity Essentials

Posted on Nov 20, 2024 in Chemistry

Nuclear Reactor Basics

A nuclear reactor is an installation where nuclear reactions occur. Key components include:

  • Fuel Rods: Mixed uranium-containing aluminum, allowing fluid circulation.
  • Reactor Core: Contains fuel rods, typically cooled with H2O.
  • Control Rods: System to start or stop nuclear fission chain reactions.
  • Moderator: Ensures continuity in the chain reaction by managing neutron speeds.
  • Refrigerant: Removes fission heat by plunging into the nucleus.
  • Shield: Biological shield preventing radiation leakage.

H2O in Reactors

H2O acts as both coolant and moderator. The difference between H2O and heavy water (D2O) is the deuterium content. H2O has no more than 6 deuterium, while D2O has between 170-180.

Fast Reactor

A fast neutron reactor breeds fuel, producing more fissile material than it consumes.

Atomic Structure

  • Electrons: Negative electronic charge.
  • Proton: Positive electronic charge, in the core.
  • Neutrons: Unloaded, in the core.

Nuclear Energy

Obtained by fission or fusion, releasing large amounts of energy with a decrease in mass.

Radioactivity

Emission of energy during the decay of unstable atomic nuclei (Alpha, Beta, Gamma, Neutrons).

  • Alpha Radiation: Positively charged particles, similar to a helium nucleus.
  • Beta Radiation: Particle size of an electron, lower ionization than alpha.
  • Gamma Radiation: High energy, greater penetrating power than Alpha and Beta.
  • Neutrons: Produce fission or other nuclear reactions.

Radioisotopes

Artificial radioactive elements produced in reactors and accelerators. Half-life is the time for half the radioactive material to decay.

Nuclear Reactions

  • Fission: Nucleus rupture into two fragments, releasing neutrons.
  • Fusion: Union of light atoms to form heavier atoms.

Uranium

Contains fissionable nuclei, the primary reactor fuel material.

Radioactive Waste

Material contaminated by radionuclides above specified levels.

Measurement Units

Curie (Ci): 1 Ci = 3.7×1010 disintegrations per second. Becquerel (Bq): 1 Bq = 1 disintegration per second. Thus, 1 Ci = 3.7×1010 Bq.

Applications of Radioactivity

  • Radiotherapy: Inhibits and destroys affected cells.
  • Radioimmunoassay: In-vitro technique mimicking life processes.
  • Radiology: Detects diseases in heart, lungs, kidneys, brain.
  • Industry: Streamlines processes and controls production.
  • Food: Techniques for longer shelf life through radiation.

Radioactivity in Chile

Started in 1955. CCHEN manages civilian applications, including medicine, food, hydrology, with facilities at Lo Aguirre and La Reina.