As crews demolished a shuttered nuclear weapons plant during 2017 in central Washington, specks of plutonium were swept up in high gusts and blown miles across a desert plateau above the Columbia River.

The releases at the Department of Energy cleanup site spewed unknown amounts of plutonium dust into the environment, coated private automobiles with the toxic heavy metal and dispensed lifetime internal radioactive doses to 42 workers.



For the record: An earlier version of this article said that work was stopped five years ago on a $16.8-billion waste treatment plant. Work did stop on key parts of the plant, but there were portions that continued to operate.

The contamination events went on for nearly 12 months, getting progressively worse before the project was halted in mid-December. Now, state health and environmental regulators, Energy Department officials and federal safety investigators are trying to figure out what went wrong and who is responsible.