TRI-CITIES, Wash. (AP) — The U.S. Department of Energy has confirmed that two underground structures at the decommissioned Hanford nuclear reservation in Washington state have been stabilized after they were deemed at risk of collapsing and spreading radioactive contamination into the air. Tri-City Herald reported Tuesday that a federal study in 2020 found that three underground structures where plutonium-contaminated liquids were stored posed a high risk of collapse and contamination. Central Plateau Cleanup Co. President Scott Sax told employees that the structures were filled with concrete-like grout to prevent them from collapsing. The work was done by White Shield Inc. of Pasco under a contract originally valued at about $4 million.