Yucca Mountain is a barren desert ridge about 90 mi (161 km) northwest of Las Vegas, Nevada. The U.S. Department of Energy plans to build its first high-level nuclear waste storage facility there in an extensive series of tunnels deep beneath the desert surface. Choosing this site has been a long and divisive process. Although over 20 years and more than $7 billion have been spent designing and testing the storage facility, scientists are still not clear whether the facility will remain dry and stable for the thousands of years it will take for natural decay processes to make the wastes less radioactive.

Most of the nuclear waste to be stored at Yucca Mountain will come from nuclear power plants. As radioactive uranium 235 is consumed in fission reactions, the fuel becomes depleted and accumulating waste products reduce energy production. Every year about one-third of the fuel in a typical...