An apparent surge in leakage from a huge tank of radioactive waste set off alarms at the Hanford nuclear site in south-central Washington. This involves an aging, double-shelled tank that contractors were slowly pumping out.

On Sunday, instruments detected a sharp rise of toxic brew in the space between the inner and outer tank shells. The Washington Department of Ecology said in a statement Monday that it has no indication radioactive waste is leaking into the environment or poses a threat to public health.

Still, Governor Jay Inslee said it’s obviously unwelcome news.

“We don’t want to see any leaking through any of these skins. That’s why we have been insistent on the federal government accelerating this cleanup,” Inslee said. “As you know, with the aid of the (state) attorney general we are holding the federal government’s feet to the fire to insist that they meet these timelines.”

According to the U.S. Department of Energy, the tank pumping work is currently on hold while engineers evaluate the situation and prepare a plan to drain the sludge that leaked between the two walls of the tank.