The Nuclear Fuel Cycle Explained!

by | May 26, 2024 | Glossary and FAQs

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The nuclear fuel cycle refers to the succession of industrial activities that generate electricity from uranium in nuclear power reactors. The process begins with the mining and milling uranium ore, which is then enriched and converted into nuclear fuel. After the fuel is utilised in reactors, the cycle continues with the handling of spent fuel, which can be recycled for future use or disposed of as radioactive waste. This cycle assures a steady and regulated nuclear energy supply while balancing energy requirements with environmental and safety concerns.

Nuclear Fuel Cycle

The nuclear fuel cycle comprises two phases: the front end and the back end. Front-end processes prepare uranium for use in nuclear reactors. Back-end steps guarantee that used (or spent) nuclear fuel, which is still highly radioactive, is safely controlled, processed, and disposed of.

The Nuclear Fuel Cycle Explained!

Source: EIA

Nuclear power facilities generally use one type of uranium for nuclear fission as its atoms are easily separated. Although uranium is approximately 100 times more abundant than silver, U-235 is relatively rare, accounting for slightly more than 0.7% of natural uranium. U-235 is extracted from uranium ore in uranium mills or slurry in in-situ leaching facilities to make uranium concentrate, which can be utilized as fuel. The uranium concentrate is first converted and enriched to enhance the level of U-235 in the uranium to 3%-5%. Then, it is processed in reactor fuel fabrication factories to produce reactor fuel pellets and fuel rods.

Nuclear fuel is placed into reactors and used until it becomes highly radioactive. It must then be removed for temporary storage before disposal. Spent fuel material can be treated to recover any leftover uranium that can be fissioned back into a new fuel assembly; however, this is not allowed in the United States.

The Initial Step of the Cycle

1. Exploration

The cycle begins with uranium exploration and mining. Various techniques are used to locate uranium, including aircraft radiometric surveys, chemical sampling of groundwater and soils, and exploratory drilling to understand the geology better. Once uranium ore deposits are identified, the mine developer often conducts more closely spaced infill, or development drilling, to estimate how much uranium is available and how much it will cost to collect.

2. Uranium Milling

After being mined from an open pit or underground mine, uranium ore is refined into uranium concentrate using a uranium mill. The ore is crushed, pulverised, and ground to a fine powder. Chemicals are added to the fine powder, causing a reaction to separate the uranium from the other minerals. Groundwater from solution mining operations is pumped through a resin bed to recover and concentrate uranium.

3. Uranium Conversion

The next phase in the cycle is to convert yellowcake to uranium hexafluoride (UF6) gas at a converter facility. U-234, U-235, and U-238 are the three naturally occurring uranium isotopes. Present nuclear reactor designs in the United States require a higher concentration (enrichment) of the U-235 isotope to function correctly. The uranium hexafluoride gas made in the converter facility is natural UF6 because the original uranium isotope contents remain constant.

4. At The Reactor

Trucks take the fuel assemblies to the reactor sites after they have been constructed. The fuel assemblies are kept on-site in new fuel storage bins until the reactor operators use them. At this point, the uranium is only weakly radioactive, and virtually all radiation is trapped within the metal tubes. Typically, reactor operators replace about one-third of the reactor core (40 to 90 fuel assemblies) every 12 to 24 months.

5. The Tail End of The Cycle

After being used in the reactor, fuel assemblies become more radioactive and must be removed and immersed in a pool of water at the reactor site for several years. Although the fission reaction has halted, the spent fuel emits heat due to the decay of the radioactive elements formed when the uranium atoms are split apart. Water in the used fuel pool cools the fuel while also preventing radiation from being released. From 1968 to December 31, 2017, 276,879 fuel assemblies were discharged and stored at both closed and operational and at 119 commercial nuclear reactors in the United States.

In conclusion, the nuclear fuel cycle, which includes mining, fuel manufacture, reactor operating, and waste management, is critical to maintaining nuclear energy’s long-term viability. Its sound management is essential for increasing energy output while reducing environmental impact and guaranteeing safety. As technology advances, the cycle promises more efficiency, less waste, and better safety standards, all of which will contribute significantly to the future of clean energy.

Also Read: Is Nuclear Waste Radioactive?

 

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  • Michael Thompson

    Michael Thompson is an esteemed expert in the renewable energy sector, with a profound experience spanning over 25 years. His expertise encompasses various sustainable energy solutions, including solar, wind, hydroelectric, and energy efficiency practices. Michael discusses the latest trends in renewable energy and provides practical advice on energy conservation.

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