In Our Electric Grid – Electrical Generation Basics, I introduced the basic steam cycle in my discussion. In Our Electric Grid – Fuel Sources Part 1, I presented the basics about coal and gas fuel sources. In this part, I am introducing the basics of nuclear fuel sources.
Now I will mention that there are numerous types of reactor designs, including different nuclear fuels, different fuel mixtures, boiling water reactors, pressurized water reactors, and different methods for controlling nuclear reactors. In my future blogs, I will be discussing the GE Hitachi Nuclear Energy – Economic Simplified Boiling Water Reactor (ESBWR), which is one of the reactors I studied for my bachelor’s degree. If you would like me to discuss another type in the future, please let me know in the comments below.
In the ESBWR reactors, uranium 235 (abbreviated U-235). U-235 is actually found naturally, and is mined. Although, natural uranium only contains about 0.7% U-235, the remaining 99.3% is primarily a U-238 isotope, which isn’t useful for reactor fuel. Numerous facilities exist that enrich the uranium by physically separating the isotopes of uranium. Civilian plants typically use 3% – 5% enriched uranium (they are prevented from using anything higher due to nuclear treaties), which is a level that is low enough that it is impossible to create a nuclear weapon with. Theoretically, one kilogram of U-235 can release as much energy as 1500 tons of coal, if it were able to fission 100% of the U-235.
At the highest level, you can think of the uranium simply as a hot rock. Inside the reactor, while it is operating, the U-235 fuel is fissioning. (In a later blog posts, I will discuss how the process of how fission works in these reactors, safety concerns, and how they are controlled.) The process of the U-235 fissioning produces tremendous amounts of energy in the form of heat. Water is in contact with the fuel rods inside the reactor, which allows for the heat to transfer from the fuel into the water. In the ESWBR plants, the water is actually allowed to boil inside the fuel channel, which creates the steam. From there, it starts the basic steam cycle, as I mentioned in my Our Electric Grid – Electrical Generation Basics post.
I will continue discussing nuclear power in the near future, but next week I will begin introducing some information about renewable energy sources – so stay tuned and leave comments/suggestions!!!