Governor Inslee said a planned state enforcement order would require the U.S. Department of Energy to determine the cause of the collapse and assess if any other tunnels are at risk of failing as well.
Workers have most of the road in place to get heavy equipment to the collapsed tunnels site.
The Hanford facility has some 9,000 employees, most of whom were told to stay home on Wednesday, Henderson said. The DOE said the cave-in involved a 20-foot-long section where two tunnels intersected, reported CBS.
The collapse of a tunnel containing radioactive waste at the Hanford nuclear weapons complex underscored what critics have always been saying: The toxic remnants of the Cold War are being stored in haphazard and unsafe conditions, and time is running out to deal with the problem.
There was an emergency situation at this site in Washington state after a tunnel full of highly contaminated materials collapsed.
As per many reports, the region was built in the time of Cold War era, which situated in the 20-by-20 feet of area in hundreds of feet long stretch, now the soil of upper layers of the tunnel has been collapsed.
The Energy Department also confirmed that no action was required for the almost 300,000 residents in the surrounding Benton and Franklin communities, according to AP. Now, about 8,000 people are working on a massive cleanup that is expected to cost more than $100 billion and last through 2060. Worker safety has always been a concern at Hanford, which is located about 200 miles southeast of Seattle. Officials say that no workers were injured in the vicinity.
Tuesday's collapse is the latest incident to raise safety concerns at the sprawling site that made plutonium for nuclear bombs for decades after World War II.
Smith said the tunnel contains about 780 cubic yards (596 cubic meters) of waste - a mixture of radioactive and chemical waste and irradiated equipment, including the contaminated rail cars used to haul the fuel rods.
Hanford, located in southcentral Washington state, has about 9,000 employees and a lot of them were told to stay home Wednesday. "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". Much of it would wear out and would be coated with radioactive waste.
Pallone said the Energy Department should provide details on the implications of the incident on continuing cleanup efforts.
Cleaning up radioactive materials at the Hanford site, which is a federal facility, has been one of the Energy Department's priorities for years.
The budget for Hanford alone is about $2.3 billion in the current fiscal year, about $1.5 billion of that going to the management and treatment of approximately 56 million gallons of radioactive liquid waste stored in underground storage tanks.