An emergency was declared at the Hanford nuclear reservation in Eastern Washington state on Tuesday after the roof of a tunnel used to store highly radioactively contaminated waste collapsed.
Several thousand workers were ordered to take shelter, most of them for several hours, in buildings with ventilation systems shut down to protect against any possible airborne contamination.
The emergency was declared Tuesday morning after workers conducting routine monitoring in central Hanford noticed an anomaly on the Hanford landscape.
They saw what appeared at a distance to be a 2 to 4 foot deep depression in the soil over one of the waste disposal tunnels at the defunct PUREX processing plant tunnels.
An aerial check showed that a hole caved in the top of the tunnel, potentially exposing the highly radioactive material stored inside to the atmosphere.
No airborne radiation had been detected as of 5 p.m. Tuesday. Radiological surveys were continuing.
No workers were hurt, none were known to be contaminated and all were accounted for, according to the Department of Energy.
Hanford, a 580-square-mile site near Richland, produced plutonium from World War II through the Cold War. Parts of the site remain heavily contaminated with radioactive and hazardous chemical waste.
People in the nearby Tri-Cities and rural areas were assured that no airborne contamination left the site as a result of the tunnel breach and no protective actions needed to be taken off site.
The tunnel is about 19 miles northwest of Richland in the Hanford nuclear reservation’s 200 East Area, which is near the center of the nuclear site. It’s about seven miles from the Columbia River.
By late afternoon the incident was moving from an emergency phase to a recovery phase, according to DOE.
A crew was preparing to fill the hole with clean soil, DOE said Tuesday evening.
As of mid afternoon most workers had safely left the site and nonessential workers were told not to report for the swing shift if they work north of the Wye Barricade, the southernmost security gate where guards are stationed to admit workers onto the closed site.
A decision had not been made early Tuesday evening on whether workers not essential to safety at the site should report to work sites north of the Wye Barricade on Wednesday.
The PUREX tunnel that breached was built of creosoted timbers and concrete and topped with about eight feet of soil.
It was used for the disposal of large pieces of highly radioactive material contaminated from use at the PUREX plant. The massive plant was central to Hanford’s mission of producing plutonium for the nation’s nuclear weapons program through the Cold War.
Railroad cars loaded with contaminated equipment were backed into the tunnel by a remotely operated engine and left there, with the door eventually sealed closed.
Radiation levels of wastes stored there would be lethal to humans within an hour, according to Heart of America Northwest, a Seattle-based Hanford watchdog group.
The tunnel with the breach was used from 1960 to 1965. In 1964 a longer and more reinforced tunnel was added at PUREX.
Energy Secretary Rick Perry was visiting the Idaho National Laboratory at Idaho Falls on Tuesday and was briefed on the emergency, according to DOE.
Washington Gov. Jay Inslee said DOE notified him of the emergency Tuesday morning, which was followed by a call from the White House to alert him, as well.
“This is a serious situation, and ensuring the safety of the workers and the community is the top priority,” Inslee said. “We will continue to monitor this situation and assist the federal government in its response.”
Oregon Gov. Kate Brown said she also was monitoring the situation. The Columbia River flows through Hanford and then along the border between Washington and Oregon.
Oregon set up an operations center in Salem as a precaution.
The incident should serve as a reminder that “the temporary solutions DOE has used for decades to contain radioactive waste at Hanford have limited lifespans, whether they are underground tunnels for storing contaminated equipment or aging steel tanks filled with high-level radioactive waste,” said Sen. Ron Wyden, D-Ore.
“The longer it takes to clean up Hanford, the higher the risk will be to workers, the public and the environment,” he said.
Sen. Patty Murray, D-Wash., said she sent her “deepest appreciation to the first responders who are on the scene and all those who are working very hard to figure out the situation on the ground.”
Murray, Sen. Maria Cantwell, D-Wash., and Rep. Dan Newhouse, R-Wash., all said they were following developments.
The incident became a trending topic on Facebook and Twitter.
The Hanford emergency center was activated at 8:26 a.m. and the Hanford Fire Department was called to PUREX.
About six workers were at the plant when the initial discovery was made. They were immediately evacuated.
About 3,000 workers in the 200 East Area, including about 1,000 workers at the Hanford vitrification plant, were ordered to take shelter inside buildings. Because the ventilation systems were disabled, equipment that generated heat was turned off.
After the aerial survey midmorning showed the top of the tunnel was breached, all workers north of the Wye Barricade, plus the LIGO observatory, also were told to take shelter in buildings.
The shelter-in-place order was lifted for those workers about noon.
About 1:30 p.m., workers north of Hanford’s Wye Barricade who were not needed for site safety or security were told to go home.
No one was allowed to enter the site beyond the security barricades, and flights over the reservation were restricted for much of the morning.
Work continued at the commercial nuclear power plant on leased land at Hanford outside the security barricades.
Workers at the plant, the Columbia Generating Station, were not told to stay indoors. The plant is about 12 miles from PUREX, according to Energy Northwest, which operates the plant.
Franklin and Benton counties each activated their emergency operations centers, but said the public did not need to take any protective actions.
The Richland School District told parents and others who were concerned that there was no danger that any radioactive contamination could reach its schools and that they were not affected in any way by the incident.
Washington State University Tri-Cities also assured students and alumni there was no danger at its Richland campus.
Tri-City Herald reporter Sara Schilling contributed.