The White House on Wednesday said it is confident that this week's nuclear waste incident at the Hanford weapons facility in Washington state is on its way to being resolved.

"The incident is moving from the emergency phase to the recovery phase," said White House deputy press secretary Sarah Sanders at Wednesday's regular press briefing.

A hole was discovered on Tuesday morning in one of the tunnels connected to the plutonium refining facility at the nuclear weapons complex. The Energy Department placed the facility on alert because of risk of exposure to hazardous materials in the tunnel.

She added that "after extensive testing we remain confident at this point there has been no indication of worker exposure or an airborne radiological release."

Sanders said no non-essential personnel are allowed at the site. Responders began taking steps to fill the hole at the tunnels Tuesday evening, and Sanders explained she expects those repairs to conclude on Wednesday.

She said plans are underway to prevent another tunnel breach.

Anti-nuclear activists jumped on the Hanford incident to raise new support for opposing the nation's current nuclear waste policy. "The current unfolding crisis at Hanford, the bursting barrel at Waste Isolation Pilot Plant in New Mexico in 2014, and the exploding radioactive waste dump in Beatty, Nev., in 2015, show that radioactive waste management is out of control," said Kevin Kamps with the group Beyond Nuclear.

"That's why the Yucca Mountain dump in Nevada, the Canadian dump targeted at the Great Lakes shore, and the parking lot dumps in Texas and New Mexico must be blocked, to prevent future disasters," he said.