ydinpolttoainekierto

ydinpolttoainekierto (Finnish for nuclear fuel cycle) refers to the series of processes by which uranium-based fuel is produced, used in nuclear reactors, and managed after use. The cycle typically begins with uranium mining and milling to produce yellowcake, which is converted into uranium hexafluoride and enriched to increase the fraction of U-235. Enriched uranium is fabricated into fuel assemblies and loaded into a reactor, where it sustains fission to generate heat and electricity. After irradiation, spent fuel is removed, cooled, and stored. Depending on policy and technology, spent fuel can be reprocessed to recover uranium and plutonium for reuse in mixed oxide fuels, or disposed of as high-level waste in geological repositories. In a once-through or open cycle, spent fuel is treated as waste after discharge.

The cycle also includes conversion and enrichment facilities, spent fuel management, waste handling, decommissioning, and regulation. National and international frameworks, including safeguards and safety standards, govern operations to minimize environmental impact and proliferation risk. Different reactor designs and fuel types influence the cycle length and complexity; fast reactors and breeder concepts contemplate different recycling strategies than light-water reactors. Public policy often weighs energy supply, non-proliferation, waste management, and long-term stewardship when choosing between closed and open cycles.