uraaniopolttoaine

Uraaniopolttoaine, also known as uranium fuel, is the material used in nuclear reactors to sustain a controlled nuclear chain reaction. It is typically composed of enriched uranium, meaning the concentration of the fissile isotope uranium-235 has been increased above its natural abundance. Natural uranium consists of about 99.3% uranium-238 and only about 0.7% uranium-235. For most nuclear power reactors, the uranium-235 concentration is enriched to between 3% and 5%.

The most common form of uranium fuel is in the shape of ceramic pellets made from uranium dioxide (UO2). These pellets are then stacked end-to-end within long metal tubes, usually made of a zirconium alloy, forming fuel rods. Many fuel rods are then bundled together into fuel assemblies, which are loaded into the core of a nuclear reactor. When a uranium-235 nucleus absorbs a neutron, it undergoes fission, splitting into two smaller nuclei, releasing a significant amount of energy in the form of heat, and emitting more neutrons. These neutrons can then cause further fissions, creating a self-sustaining chain reaction that generates the heat used to produce electricity.

The design and composition of uraaniopolttoaine are critical for safe and efficient reactor operation. Factors such as enrichment level, fuel pellet size, and fuel rod cladding material are carefully controlled. Spent nuclear fuel, which remains after the fissile material has been depleted, is highly radioactive and requires careful handling and storage.