Uranium Enrichment
Natural uranium consists primarily of U-235 and U-238. When neutrons collide with U-235, it emits huge amounts of energy through a fission reaction, whereas U-238 is less fissile than U-235.
Since natural uranium are contains only approximately 0.7% of U-235, isotope separation (uranium enrichment) is needed to increase its content to 3 to 5% to be used as fuel for light water reactors.
JNFL has a plan for the Uranium Enrichment Plant to provide for an maximum capacity of 1,500 ton-SWU/year.
Enrichment methods
The concentration of U-235, with which nuclear fission occurs, is increased from approximately 0.7% to 3-5%. Enrichment methods include the gaseous diffusion process, the laser enrichment method, and the centrifuge process, which JNFL uses.
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![](/en/business/uran/image/feed-and-withdrawal-room.jpg)
Feed and Withdrawal Room
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Homogenization Room
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Uranium enrichment process
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Cascade room where centrifuges, linked with each other, are placed
Since a single centrifuge can only increase the enrichment by a slight degree, the process must be repeated by many centrifuges to attain the level of enrichment required for light water reactors. A series of centrifuges —a "Cascade"— is thus linked to produce the necessary level of enrichment.
The maximum enrichment level of uranium 235 at JNFL's Uranium Enrichment Plant is limited to 5%.
Domestic technology developed in Japan
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Diagram of a centrifuge
Feeding a gaseous uranium compound, uranium hexafluoride, into a rapidly spinning rotor of a centrifuge separates U-235 and U-238. The heavier isotope, U-238 is pushed outward, while U-235, the lighter isotope, gathers at the center of the rotor. Gas with the higher U-235 concentration is drawn off and sent to another centrifuge. Repeating this process several times produces uranium with increase U-235 content. Using this method, JNFL developed an advanced centrifuge with high efficiency and safety, based on the Japan Atomic Energy Agency’s technology.