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Nuclear fuel cycle is a combination of techniques for mining uranium, nuclear reactor fuel production and preparing the fuel for the use and after-use disposal. The notion “fuel cycle” specifies the fact that spent or irradiated nuclear fuel (SNF) can be regenerated after special treatment. The nuclear fuel cycle, including ultimate disposal of high-level waste, takes generally 50 to 100 years.
Nuclear power fuel cycle can be divided into three phases. The initial phase covers uranium ore mining through supply of fabricated fuel assemblies to NPP sites. The next phase includes reactor operation to generate electricity and temporary store SNF at NPP site. The final phase includes several operations: irradiated fuel transportation to a special storage facility or SNF reprocessing plant and burial of vitrified high-level waste after reprocessing.
At present, most of the countries use so-called open nuclear fuel cycle. The closed nuclear cycle envisages transportation of irradiated FAs to radiochemical plants to extract unburned uranium rather than transportation to disposal site. Recoverable uranium could amount up to 95 % of initial uranium mass. Then, this material is subject to same processing stages as the one mined.
Extraction and disposal of radioactive isotopes of various chemical elements is carried out in parallel. Additionally, radioactive waste is extracted (its share is less than 3% of uranium mass contained in fresh fuel). It is reprocessed and placed in glass matrices, which are sent to special repositories. This constitutes the final phase.
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