Nuclear Physics

Nuclear Physics Perth Mod Sem 2

Advantages and Disadvantages of Nuclear Power

Advantages and Disadvantages of Nuclear Power

Advantages:

• Low Greenhouse Gas Emissions

• High Energy Output

• Energy Security

Disadvantages:

• Nuclear Waste

• Accidents/Disasters such as Chernobyl

• High Initial Costs

Radioisotopes

Radioisotopes are unstable isotopes with elements with the same number of protons but different neutrons meaning they have an unstable combination of neutrons and protons. This results in excess energy in their nucleus causing the radioactive isotope to emit radiation in the form of alpha, beta or gamma rays to transform the isotope into a more stable form. 

Half-life

Amount of time it takes for one-half of the atom to decay.

Three Types of Radiation

Alpha (α):

• Particles made up of 2 protons and 2 neutrons, which is basically a helium atom.

• Can be stopped by paper and skin and is slow

• Mass is 0 and Charge is +2

• Atomic no. decreases by 2 and mass by 4

Beta (β):

• Particles made of electrons (or sometimes, positrons).

• Greater than alpha but stopped by plastic, glass or aluminum and is fast

• Mass is ~1/2000 and charge is -1

• Atomic number increases by 1 and charge is unchanged

Gamma (γ):

• Electromagnetic Waves with no mass or charge

• Greater than Beta and Alpha and stopped by lead or concrete and is very fast, at the speed of light

• Mass is 0 and charge is 0

• Atomic number becomes unchanged and charge is unchanged

Subatomic particles

• Protons = Positive (Nucleons), Mass = 1, In Nucleus

• Neutrons = Neutral (Nucleons), Mass = 1, In Nucleus

• Electrons = Negative, Mass ~0.0005, In orbit around Nucleus

Atomic Number and Atomic Mass

Atomic Number = number of protons in nucleus of an atom

Atomic Mass = number of protons + neutrons

(thus to find neutrons, Atomic Mass - Atomic Number = Neutrons)

Strong Nuclear Force (SNF)

Force between two or more nucleons (protons and neutrons), binding protons and neutrons together in nucleus.

Electromagnetic/Electrostatic Force (ESF)

Repulsion of charged protons

Strong Nuclear Force (SNF) and Electromagnetic/Electrostatic Force (ESF)

• SNF holds all the protons and neutrons close together, and the ESF acts to push protons further apart.

• Where atoms are small, the SNF force overpowers the ESF but as it gets bigger, the ESG becomes grater than the SNF

• They eject particles and energy in order to return to a stable state.

Deflection of Radiation

Magnetic and Electric fields: Alpha is positive, beta is negative (most of the time) and gamma radiation is neutral. This means that alpha and beta can be deflected in the opposite direction by these fields.

Background Radiation

• Radioactivity in all plants and animals

• The sun and space

• Buildings

• The ground

• Waste Materials, and “leaks” from nuclear power stations

Ionisation

Process in which a neutral atom or molecule acquires or loses an electrical charge, producing an ion. Examples include alpha particles, gamma rays, x-rays and neutrons.

Nuclear Reactor Components

Fuel - Usually pellets of uranium oxide forming fuel rods

Moderator - Material which slows down the neutrons released, generally water or heavy waters

Control Rods - Absorbs the neutrons to control the rate of reaction.

Coolant - Liquid or gas circulating in the core transferring heat from it

Steam generator - Part where heat from the reactor is used to make steam for the turbine

Nuclear Waste in the ecosystem

The earth’s water cycle is the main way that radiation gets spread. This means that the surrounding vegetation and ingested by animal life. This is mainly produced from clothing contact with radioactive materials, remains of lab animals and old medical radiation equipment.

Fusion

Joining of two lighter nuclei to form one heavier nucleus. Often requires a huge amount of energy but releases a massive amount of energy.

Fission

Splitting of a heavier nucleus into smaller nuclei. Often initiated by neutron capture and releases large amounts of energy.