Samples uncover new danger in Hanford tanks

SEATTLE – Traces of a potentially deadly chemical have been detected for the first time in samples from underground waste tanks at the Hanford nuclear site. A citizens watchdog group has raised concerns about worker safety.

The chemical, dimethyl mercury, can be inhaled, ingested or absorbed through the skin. Depending on the amount and type of exposure, the substance can irritate the eyes, skin and lungs, or result in damage to the central nervous system or death. Dimethyl mercury had never been detected near Hanford’s 177 underground tanks because no one had looked for it. The tanks hold 53 million gallons of radioactive liquid, sludge and saltcake from decades of nuclear weapons production.

The contractor handling the tank waste cleanup, CH2M Hill Hanford Group, began sampling for the substance for the first time this summer after it was detected at the Savannah River nuclear site in South Carolina. The sampling was conducted at a group of 12 tanks known as C-Farm. Those tanks were targeted because their basic mercury levels posed the greatest potential among Hanford’s tanks to produce dimethyl mercury, said a CH2M Hill spokeswoman.