The Reliability of Uranium-235

Jack Jones
February 20, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: This diagram depicts a nuclear power plant. It illustrates how electricity is generated from splitting the uranium fuel through nuclear fission. (Source: Wikimedia Commons)

Nuclear power plants generate heat through a process called nuclear fission. As seen in Fig. 1, nuclear fission involves the splitting of uranium atoms to create heat, which boils water to make steam. The steam then propels turbines to create electricity. The uranium atoms are packaged into tiny ceramic pellets and stored in the nuclear reactor as fuel. Unlike coal, oil, and natural gas plants, nuclear power plants do not burn anything. They use the physical process of nuclear fission to generate an immense amount of energy in the form of heat that can ultimately produce electricity. Therefore, no air pollution or greenhouse gas emission are associated with the energy source. Finally, they can be constructed anywhere, and if controlled properly, do not disrupt the environment around them.

Unparalleled Reliability

Nuclear power is the most reliable source of electricity, sustaining the highest national average reliability. America's next two most reliable clean energy sources, geothermal and biomass, run at significantly lower reliability rates. What is more, both of these energy sources produce significantly less electricity than nuclear power. Nuclear power generates 2.8 trillion kilowatt-hours of electricity annually in the US. [1] The plants are so reliable because of the energy-intensive nature of uranium. A uranium pellet's size is equivalent to the size of an eraser, but it boasts the same energy as 1,780 pounds of coal, 149 gallons of oil, or 17,000 cubic feet of natural gas. [2] Therefore, nuclear power plants only need to be refueled every 18-24 months, offering a dependable energy source that can power the electrical grid at all times. Finally, weather, transportation, and other obstacles do not affect the supply of uranium, whereas they can have significant consequences on coal, oil, and natural gas.

Future Limitations

While uranium is very reliable, it is a non-renewable energy source, meaning that it will eventually run out or not be replenished within multiple generations. Uranium is a very common element located in rocks throughout the globe. However, nuclear power plants require a certain isotope of uranium, U-235, that is very rare. As a result, eventually the supply of U-235 will run out, a situation that will have catastrophic effects on electrical grids unless another form of sustainable energy is properly implemented.


Nuclear power is an efficient and reliable energy source that does not contribute to anthropogenic climate change and pollution. It provides clean, dependable energy. However, it is important to be mindful of the finite supply of U-235. Eventually, this supply will run out, so it is imperative world leaders either discover ways to prevent U-235 from expiring or shift focus to developing and implementing an efficient and cost-productive renewable energy source.

© Jack Jones. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] S. Fetter, "How Long Will the World's Uranium Supplies Last?," Scientific American, 26 Jan 09.

[2] M. Brandly, "The Case for Nuclear Power," Virginia Viewpoint, No. 2001-9, October 2001.