The initial work has begun to clean up a spill of Hanford waste so radioactive that it would be lethal within two minutes of contact.
Workers have entered the airlock of the nuclear reservation’s 324 Building for the first time in 15 years.
Beneath the Cold War-era building lies the spill of cesium and strontium, a nasty surprise found by workers in 2010.
The building, which is about 1,000 feet from the Columbia River, has been left standing to provide shielding from the radiation beneath it until contamination can be removed using remotely operated equipment.
Entering and cleaning out the airlock is an early step toward installing the equipment to clean up the spill and then tear down the building.
Contractor CH2M Hill Plateau Remediation Co., the Department of Energy contractor responsible for the work, plans to have old equipment and other debris that was left in the airlock removed this year.
The work they are doing now is critical to making sure we are successful when we start soil removal.
Bryan Foley, DOE project director
It also plans to finish work on a mockup facility already being used. Equipment can be tested there and employees can practice the tasks that must be done in radioactively contaminated areas, working out any issues in a safe environment.
“The work they are doing now is critical to making sure we are successful when we start soil removal,” said Bryan Foley, DOE project director.
The 324 Building, built in the mid-1960s and operated until 1996, housed thick-walled rooms called “hot cells” where workers used remotely operated equipment to perform work with highly radioactive materials.
As workers were decontaminating the building for demolition in 2010, they discovered the cesium and strontium that had leaked from the B Cell into the soil.
A spill during work in the 1980s for Germany is suspected of making its way through the cracked lining of a sump at the bottom of the cell. Workers were fabricating concentrated cesium and strontium into a heat source for Germany to test a repository for radioactive waste, which emits heat.
By stopping the planned demolition when the spill was discovered and leaving the building standing, the structure not only provides a barrier against the radiation, it acts as an umbrella. Precipitation could carry contamination deeper in the soil toward the groundwater.
The 324 Building is one of only a few buildings still standing in the 300 Area, as more than 170 buildings in the Hanford complex just north of Richland have been demolished as part of environmental cleanup over the last decade.
DOE faces a legally binding deadline, revised after the spill was discovered, to have the building down and any remaining soil contamination beneath it cleaned up by fall 2021. The remote excavation of the spill is required to be completed by fall 2019.
New plans call for installing remotely operated equipment in B Cell to cut through the floor, to dig up the contaminated soil and to load it out.
At Hanford’s Maintenance and Storage Facility, a 28,000-square-foot building no longer needed to serve the deactivated Fast Flux Test Facility, some of the testing for the 324 Building project is being done.
Mockups have proved extremely valuable in performing dry runs on work.
Bill Kirby, CH2M vice president for the Hanford 300 Area
A steel-reinforced concrete pad has been built in the building to replicate the floor of the hot cell. Operators are using it to test a remotely controlled, prototype saw.
So far the saw is performing as expected, said Bill Kirby, CH2M vice president for the Hanford 300 Area.
“We need to be very confident when it goes in the cell that it is going to do its full job and we don’t have any questions to resolve,” said Mike Thien, CH2M testing manager.
If the saw is installed in B Cell and does not work correctly, it would mean not only that the equipment is contaminated but workers could be needlessly exposed to radiation as the saw is moved in and out of the hot cell.
At a second location off Hanford on Horn Rapids Road a mockup of the B Cell has been built for worker practice and to test the equipment that will be used to clean up the contamination.
30 feet height of B Cell
5 feetthickness of B Cell walls
“Mockups have proved extremely valuable in performing dry runs on work,” Kirby said.
Before workers entered the airlock for the first time, they repeatedly practiced, including getting into multiple layers of protective gear and carefully removing them to prevent the spread of any contamination.
“(It) is really helping us to learn the steps, figure out what we need to do first to get somebody in there and get them back out safely,” said Tim Renz, radiological control technician.
The airlock will be the hub of the project. It is an intermediate area, with some contamination, between the clean outer areas of the 324 Building and its highly contaminated hot cells.
The equipment for remote operations in B Cell will pass through the airlock into the cell for installation and the contaminated waste will come out of the hot cell through the airlock.
Plans call for installing a remotely operated excavator arm on the 30-foot-high, 5-foot-thick walls of B Cell. It will be used first to break up a layer of grout on the floor of the cell.
There really is progress being made.
Bryan Foley, DOE project director
Then the saw will be used to cut through the floor’s stainless steel liner and the concrete beneath. Because the waste is believed to have leaked into the soil at the joints around the edges of the 22-by-22-foot floor of the hot cell, a 3-foot-wide trench will be cut around the perimeter.
Digging up the soil 10 feet deep around the perimeter of the hot cell with the excavator arm is expected to remove the worst of the contamination. Grout will be used to refill the excavated area to keep the building stable.
The most contaminated soil will be placed in boxes in other hot cells served by the airlock and and grouted for removal when the building is demolished.
Now workers wearing powered air-purifying respirators are cleaning out the airlock to prepare a working area for the project.
It is cluttered with some smaller debris that can be covered with fixative to keep contaminants in place, wrapped in plastic and then packaged in waste boxes. Some larger equipment also will have to be removed, including a cable reel and a televator used to lift people.
Next year the mock up facility on Horn Rapids Road is expected to be used for worker practice and testing of equipment now being purchased, including the remotely controlled excavator arm, lights and a camera.
Practice both improves worker safety and makes work as efficient as possible in hazardous areas, Foley said. By practicing the steps of the project, workers and management will know how many workers are needed and what each should be doing.
“There really is progress being made,” Foley said.