Separative work (SWU)

SWU

The measure of the effort an enrichment plant spends splitting uranium into an enriched stream and a depleted one, counted in separative work units (SWU). The work rises steeply with the target enrichment. With natural uranium as feed and depleted tails at 0.25% uranium-235, a kilogram of typical 4.5% power reactor fuel needs about 7 SWU and about 9 kg of natural uranium, while a kilogram at 19.75% needs about 41 SWU and about 42 kg. Those are calculated from the standard formula, not measured, but they show why a fleet running on HALEU needs far more enrichment capacity for each kilogram of fuel than today's fleet does. Modern centrifuges use about 40 to 50 kWh of electricity per SWU.

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