A giant blob of radioactive waste is expanding inside a million-gallon tank buried at the Hanford nuclear reservation in Washington state, and the Department of Energy and site contractor Lockheed Martin are baffled by the problem. A pump that was supposed to dissipate pockets of hydrogen gas in the tank instead whipped the contents into a state that resembles a rising souffle, which threatens the functionality of tank instruments and could eventually overflow, officials say. They are rushing to pump some of the waste into another tank. In June, Hanford chemist Stephen Agnew sent an email to project consultant Donald Oakley saying, “It is amazing that the level [in the tank] has reached 435 inches and no one is freaked out yet.”