Environmental Science 14th Edition by Tyler Miller ,Scott Spoolman

Exercise 11

Uranium (U) is a mineral resource obtained from uranium ore in various types of rock at different concentrations. It is used as a fuel in the reactors of nuclear power plants. A high-grade ore has 2% U and a low-grade ore has 0.1 % U. The estimated worldwide recoverable resources of uranium weigh 4,743,000 metric tons. The United States has about 7% of the world's uranium resources, which amounts to about 332,000 metric tons.
Given that current worldwide usage of uranium is about 66,500 metric tons per year, how long will the world's present recoverable uranium resources last