BOISE, Idaho (AP) — U.S. officials say problems plaguing a nuclear waste treatment plant in eastern Idaho appear to be solved, and converting high-level radioactive liquid waste into safer, more easily managed solid material could start early next year.

The U.S. Department of Energy said Thursday that a test startup without waste will begin next week at the 890-square-mile site. The 900,000 gallons of waste comes from processing spent nuclear fuel to recover enriched uranium.

The waste sits in tanks above a giant aquifer that supplies water to cities and farms.