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Washington Gov. Jay Inslee says the state issued an order requiring the federal government to determine the cause of a tunnel collapse Tuesday at the Hanford Nuclear Reservation near Richland, Wash.

The collapse left a 400-square foot hole over the tunnel containing radioactive waste stored on the former plutonium production site.

“I am extremely concerned about what happened yesterday, and how the Department of Energy can give us confidence that this will not happen again,” Gov. Inslee said during a press briefing Wednesday. “We’ve always known that we have great challenges at Hanford. The efforts to provide a long-term storage of the sludge and liquid waste is a tremendous challenge and we’ve got to remain insistent that the federal government comply with its obligations to do that. And we will continue to do that. But while we’re doing that we have to keep our eye on the ball to have safety for our employees who work there and -- if you have collapsing tunnels that could expose workers, this is a very dramatic concern that we have.”

The enforcement action announced Wednesday requires the Energy Department to assess if there's an immediate risk of failures in any other tunnels and take actions to safely store waste in the tunnels until a decision is made about how to permanently handle the material.

The federal agency was expected to take those actions without prodding, but the state made the move in its role as the regulator of a massive, ongoing cleanup of the site.

Inslee says the state has an obligation to protect its residents and that the action is appropriate and necessary.

The state and federal government signed an agreement in 1989 setting deadlines for Hanford cleanup activities. The state monitors activities at Hanford as part of that deal.

The Energy Department says no one was injured in the unoccupied tunnel, and no radioactive material escape.

The White House said Wednesday that the response "is moving from the emergency phase toward the recovery phase."

Sarah Huckabee Sanders, White House deputy press secretary, says the federal government remains confident there was no airborne release of radiation and no workers were exposed.

Non-essential workers at the Hanford site, which employs some 9,000 people, were told to stay home Wednesday.

Worker safety has long been a concern at Hanford, which is located about 200 miles southeast of Seattle.

Related: Sick and forgotten at Hanford

"Absolutely a huge warning to Hanford, to the federal officials who oversee that site, and to the state of Washington. There are bad things at Hanford that could blow up, that could contaminate the communities. (It would) be a three state disaster," Tom Carpenter with Hanford Challenge said. The group says its mission is to hold Hanford accountable.

Washington Attorney General Bob Ferguson filed a lawsuit last fall against the Energy Department, contending vapors released from underground nuclear waste tanks posed a serious risk to workers.