Context: To be considered 'enriched', the uranium-235 fraction should be between 3% and 5%. This process produces huge quantities of uranium that is depleted of uranium-235 and with a correspondingly increased fraction of uranium-238, called depleted uranium or 'DU'. To be considered 'depleted', the uranium-235 isotope concentration should be no more than 0.3%. The price of uranium has risen since 2001, so enrichment tailings containing more than 0.35% uranium-235 are being considered for re-enrichment, driving the price of depleted uranium hexafluoride above $130 per kilogram in July 2007 from $5 in 2001.

Question: Between what percent fraction range of uranium-235 is uranium regarded as enriched?
Answer: 3% and 5%

Question: What is the maximum uranium-235 isotope concentration for uranium to be considered depleted?
Answer: 0.3%

Question: In what year did the cost of uranium notably begin to increase?
Answer: 2001

Question: What was the price of a kilogram of depleted uranium hexafluoride in 2001?
Answer: $5

Question: How much did a kilogram of depleted uranium hexafluoride cost as of July 2007?
Answer: $130

Question: Between what percent fraction range of uranium-235 is uranium regarded as unenriched?
Answer: Unanswerable

Question: What is the maximum uranium-235 isotope concentration for plutonium to be considered depleted?
Answer: Unanswerable

Question: In what year did the cost of uranium notably begin to decrease?
Answer: Unanswerable

Question: What was the price of a pound of depleted uranium hexafluoride in 2001?
Answer: Unanswerable

Question: How much did a pound of depleted uranium hexafluoride cost as of July 2007?
Answer: Unanswerable