Ydinpolttoainejäte

Ydinpolttoainejäte, or spent nuclear fuel, refers to fuel assemblies that have been discharged from a nuclear reactor after use. It is highly radioactive and generates significant heat due to the decay of radioactive isotopes within it. The primary components of spent nuclear fuel are uranium and plutonium, along with various fission products and activation products.

The management of ydinpolttoainejäte is a critical aspect of the nuclear energy lifecycle. Immediately after removal from the reactor, spent fuel is typically stored in a spent fuel pool. These pools are large, deep concrete structures filled with water, which serves to cool the fuel and shield workers from radiation. After several years of cooling in the pool, the fuel can be transferred to dry storage casks. These casks are robust, sealed containers made of steel and concrete, designed for long-term storage on-site at nuclear power plants or at centralized interim storage facilities.

Ultimately, the long-term strategy for ydinpolttoainejäte involves permanent disposal. This is most commonly envisioned through deep geological repositories, where the waste would be isolated from the biosphere deep underground. The geological environment is chosen for its stability and its ability to contain the radioactivity for the very long timescales required for the isotopes to decay to safe levels. The development and implementation of these repositories are complex processes involving extensive site investigations, engineering designs, and regulatory approvals. Reprocessing of spent nuclear fuel is another option, where usable uranium and plutonium are extracted for reuse as new fuel, reducing the volume of high-level waste requiring disposal. However, reprocessing also generates its own waste streams and raises proliferation concerns.