To obtain uranium 235 (U²³⁵) for use in nuclear power plants, uranium containing ore containing U²³⁸ and U²³⁵ is crushed, subjected to a solvent extraction process, and then reacted with fluorine to produce uranium hexafluoride, which is a gas at ambient conditions the U²³⁵ is then separated from the U²³⁸ by various multi-stage methods that take advantage of the small mass difference between U²³⁵F6 and U²³⁸F₆, such as gas centrifuges or gaseous diffusion.

The hexafluoride gas produced from naturally occurring uranium ores contains 0.72 mole percent U²³⁵F₆ the remainder being U²³⁸F₆. It is desired to recover 25% of the U²³⁵F₆ in a gas stream enriched to 2 mole percent. What is the minimum heat and work flows necessary to accomplish this enrichment for a 1000 mole gaseous stream at ambient conditions?