Nuclear Power Study Notes

Nuclear power involves using nuclear reactors to release nuclear energy and generate electricity.
The release of nuclear energy includes nuclear fission, nuclear decay, and nuclear fusion.
As of October 2021, there were 441 nuclear reactors operating in 30 countries, providing about 10% of the world's electricity.
As of May 2021, there were 52 nuclear reactors under construction worldwide, including 14 in China and 0 in the US.

The graph shows world energy consumption by fuel in quadrillion Btu.
It includes history and projections.
Key fuels include liquids, coal (including biofuels), natural gas, nuclear, and renewables (excluding biofuels).

Annual electric generation is measured in billions of kilowatt-hours.
Countries with significant nuclear power generation include the United States, France, Russia, Japan, and South Korea.

This section shows a world map indicating countries with operating nuclear power plants (NPPs).
The map also distinguishes between countries with operating NPPs and non-nuclear countries.
The countries with the most nuclear reactors (operational reactor units in 2019):
- United States: 97
- France: 58
- China: 47
- Russia: 36
- South Korea: 23
- India: 21
- Canada: 18
- United Kingdom: 15
- Ukraine: 15
- Japan: 9
Source: World Nuclear Industry Status Report 2019.

The number of protons defines the chemical element.
The number of neutrons defines the isotope of the element.
Electrons influence the magnetic properties of an atom.
Electrons and protons interact through the electromagnetic force.
Protons and neutrons interact through the nuclear force (strong force).
The mass of the nucleus is not equal to the sum of the masses of individual neutrons and protons; this difference represents the energy released when the nucleus was formed.

Nuclear energy is released by three exoenergetic (energy-releasing) processes:
- Radioactive decay: A neutron or proton in the radioactive nucleus decays spontaneously by emitting particles or electromagnetic radiation (gamma rays).
- Fission: The breaking of a heavy nucleus into two (or more rarely three) lighter nuclei.
- Fusion: Two atomic nuclei fuse together to form a heavier nucleus.

The nucleus of an atom splits into smaller parts (lighter nuclei).
A slow-moving neutron is used to initiate the fission process.
Example: Uranium fission produces Barium and Krypton along with 3 neutrons.
Mass difference: \Delta M = M - M_p > 0, where M is the mass of initial nucleus/neutron and Mp the sum of the mass of the products.
Energy released: $E = \Delta Mc^2$
Energy released per atom: $3.2 \times 10^{-11} \text{ Joules/atom}$ ; Energy released per mole: $1.9 \times 10^{13} \text{ Joules/mole}$
The nucleus becomes captured, excited, and unstable.

The fission reaction produces more neutrons, which can induce fission in other Uranium atoms, leading to a chain reaction.
To have a controlled nuclear reaction, the speed and number of neutrons have to be controlled.

1 Uranium Fuel Pellet has as much energy available as:
- 3 Barrels of Oil (42 gallons each)
- 1 Ton of Coal (2 1/2 tons)
- 1 Cord of Wood
- 17,000 Cubic Feet of Natural Gas
Uranium has essentially no other significant application in our society except for energy production.

Fission: A heavy nucleus splits into smaller nuclei.
- Example: Uranium (235U) + Neutron → Cesium (140Cs) + Rubidium (93Rb) + Neutrons
- Energy released: approximately $200 \text{ MeV}$
Fusion: Two atomic nuclei fuse together to form a heavier nucleus.
- Example: Deuterium (2H) + Helium (3He) → Helium isotope.
- Energy released: $3.2 \text{ MeV}$

Neutrons are slowed down by colliding them with light atoms (e.g., water in US reactors).
The highest level of energy transfer occurs when the masses of the colliding particles are equal (e.g., neutron and hydrogen).

Control rods are made of a material that absorbs excess neutrons (usually Boron or Cadmium).
By controlling the number of neutrons, the rate of fissions can be controlled.

Uranium is both the fuel and the source of neutrons.
The neutrons induce the fissions.
Water acts as both the moderator and a heat transfer medium.
Control rods regulate the energy output by absorbing excess neutrons.
Nuclear energy is converted to generate steam, which drives a turbine and generator to produce electricity.

Processing of Uranium:
- Each ton of Uranium ore produces 3-5 lbs of Uranium compounds.
- Uranium ore is processed near the mine to produce “yellow cake”, a material rich in U3O8.
- Only 0.7% of U in yellow cake is 235U. Most of the rest is 238U, which does not readily undergo fission.

To be used in US reactors, fuel must be 3-5% 235U.
Yellow cake is converted into UF6, and this compound is enriched using gaseous diffusion and/or centrifuges.
Some reactor designs can run on pure yellow cake without enrichment.

Controlling the chain reaction depends on:
- Arrangement of the fuel/control rods
- Quality of the moderator
- Quality of the Uranium fuel
- Neutron energy required for a high probability of fission