"YAKIMA, Wash. -- Underground tanks that hold a stew of toxic, radioactive waste at the nation's most contaminated nuclear site pose a possible risk of explosion, a nuclear safety board said in advance of confirmation hearings for the next leader of the Energy Department."

"State and federal officials have long known that hydrogen gas could build up inside the tanks at the Hanford Nuclear Reservation, leading to an explosion that would release radioactive material. The Defense Nuclear Facilities Safety Board recommended additional monitoring and ventilation of the tanks last fall, and federal officials were working to develop a plan to implement the recommendation.

The board expressed those concerns again Monday to U.S. Sen. Ron Wyden, D-Ore., who is chairman of the Senate Energy and Natural Resources Committee and had sought the board's perspective about cleanup at Hanford."

Shannon Dininny reports for the Associated Press April 2,2013. [2]