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.
In what year did the cost of uranium notably begin to increase?
2001
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.
The price of uranium has risen since two thousand one, so enrichment tailings containing more than zero point thirty-five percent uranium-two hundred thirty-five are being considered for re-enrichment, driving the price of depleted uranium hexafluoride above one hundred thirty dollars per kilogram in July two thousand seven from five dollars in two thousand one.
In what year did the cost of uranium notably begin to increase?