* Uranium dioxide (UO2): This is the most common fuel material, usually enriched with uranium-235 to increase its fissile content. The uranium dioxide is pressed into pellets and stacked inside long, sealed tubes.
* Zirconium alloys: These alloys, such as Zircaloy, form the cladding that surrounds the fuel pellets. They have excellent corrosion resistance, high melting point, and low neutron absorption, making them suitable for the harsh environment inside the reactor vessel.
Other materials used in fuel rod design include:
* Gadolinium: A neutron absorber sometimes added to the fuel rod to control the reactor's power output.
* Stainless steel: Used for some fuel rod components, but less common than zirconium alloys due to its higher neutron absorption.
* Graphite: Can be used in some reactor designs as a moderator to slow down neutrons and increase fission efficiency.
In summary: The fuel rods are made primarily of uranium dioxide pellets clad in zirconium alloy tubes, with other materials potentially added for control and moderation purposes.
