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The mystery of uranium: Why only 0.7% of natural uranium can be used to generate electricity?
As global demand for clean energy rises, uranium has once again attracted interest as an important fuel for nuclear power generation. However, when we mention uranium, many people may not understand why the uranium extracted from nature has such a high content but only a measly 0.7% can be used to generate electricity. Understanding the isotopic composition of uranium and its enrichment process allows us to better understand the operating mechanism of nuclear energy.
Isotope composition of uranium
Natural uranium is mainly composed of three isotopes: uranium-238 (238U, accounting for 99.27%), uranium-235 (235U, accounting for only 0.7%) and uranium - 234. Efficient fission reactions can only be initiated by 235U. It is puzzling why in natural uranium, 235U accounts for such a small proportion, but we still use it for nuclear energy. The key to generating electricity.
The process of enriching uranium
To use uranium to generate electricity, it first needs to be enriched. After uranium is mined, it undergoes a grinding process to extract the uranium from the uranium ore. The product from this process, known as "yellow cake," contains about 80 percent uranium, but that's still far below the concentration needed for effective fission.
The enrichment process of uranium involves converting uranium from its original low-concentration state to a high-concentration state more suitable for use in nuclear reactors.
In a further step, as needed, the uranium is converted into uranium dioxide or uranium hexafluoride, which can be further enriched. There are currently two main commercial methods of concentration: gas diffusion and gas centrifugation, both of which are extremely energy intensive.
Challenges of reprocessing uranium
As the use of nuclear energy grows, another technology, reprocessed uranium (RepU), is also gaining attention. This process extracts usable uranium from spent nuclear fuel, although it contains unfavorable isotopes such as uranium-236 and requires additional management and monitoring.
Different grades of uranium
Uranium can be divided into many types, depending on its degree of enrichment, such as low-enriched uranium (LEU), highly-enriched uranium (HEU), etc. Different industries require uranium at different concentrations, and nearly all commercial and military nuclear reactors use enriched uranium.
In fact, low-enriched uranium usually contains between 3% and 5%, while highly-enriched uranium contains more than 20%
235U, which is a core part for military purposes.
Uranium enrichment method
The enrichment process of uranium is very challenging because the isotopes have almost identical chemical properties and cannot be separated by conventional methods. Gas diffusion and gas centrifugation are currently the mainstream concentration technologies, each with its own advantages and disadvantages.
Among them, gas centrifugation method has gradually replaced gas diffusion method as the mainstream choice due to its high efficiency and low energy consumption, while gas diffusion method is considered to be an outdated technology. As energy costs rise, there is an increasing need to develop new technologies such as laser separation methods.
The future of uranium
Facing the future, the use of uranium may continue to be updated and changed. As the research on new energy and nuclear energy deepens, the technology of uranium enrichment and reprocessing will also continue to innovate. This not only involves the supply and security of nuclear energy, but also affects the global energy pattern and the sustainable development of the environment.
Every step of uranium enrichment and use needs to be handled carefully to ensure that it does not pose a potential threat to humans and the environment.
While ensuring energy security and sustainable technological development, we should also constantly think about: In the process of global promotion of low-carbon energy transformation, will uranium still be an ideal choice for nuclear power generation?
