Hanford workers moved the first batch of highly radioactive sludge from the K West Basin near the Columbia River to central Hanford for storage Friday.
The transfer marked the culmination of three years of equipment design, system testing and operator training by contractor CH2M Hill Plateau Remediation Co. The sludge had been underwater at the K Reactor basins for more than 30 years, and it was created by the corrosion of underwater fuel stored in the basin.
"Today marks a turning point in our cleanup," said Matt McCormick, manager of the Department of Energy Hanford Richland Operations Office, in a statement. "This is a great step toward reducing the risk of the Columbia River."
It's also a major step toward preparing the K West Basin for demolition, said John Lehew, CH2M Hill president, in a statement.
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That began with getting the irradiated fuel left in the K Reactor Basins after the end of the Cold War transferred from the water to central Hanford for storage, which was completed about eight years ago.
That work has helped guide removal of the first batch of sludge to be moved, which comes from the knockout pots. The knockout pots filtered out the heaviest particles removed when fuel left in the basin was washed underwater before the fuel was removed for dry storage.
Fuel particles of irradiated uranium larger than a quarter inch are considered scrap fuel, but the smaller particles are considered sludge.
The knockout pot sludge totals less than half a cubic yard of the total 37 cubic yards of sludge that has been held in the K West Basin, including sludge consolidated from the now-demolished K East Basin.
Although it's a small portion by volume, it is highly radioactive. It contains 15,000 curies of the total 51,000 curies of the K Basin sludge, said Tom Teynor, DOE project director for sludge treatment.
The knockout pot sludge is difficult to deal with not only because it is so radioactive, but also because it is so heavy, said Mike Johnson, CH2M Hill director of sludge treatment. It weighs about 1,400 pounds.
The sludge has been taken out of the knockout pots and stored in small waste containers. Their contents are dumped onto underwater tables to wash fine materials out. A water lance is used to move the sludge around a flat screen.
All work is done at the bottom of the basins -- under about 17 feet of water -- to keep the sludge cool and protect workers from radiation. They stand on grating above the basin and perform the work with long-handled tools.
After final separation processing, the system is similar to that used for moving irradiated fuel to central Hanford.
The first of five to six anticipated batches of knockout pot sludge was been transferred to a multi-canister overpack and removed from the basin.
It was taken to the nearby Cold Vacuum Drying Facility to be vacuum dried to minimize gas generation. Then, it was taken to the Canister Storage building in central Hanford until it can be sent to a national repository for spent nuclear fuel, such as the repository that was being developed at Yucca Mountain, Nev.
"This challenging work is going smoothly and safely thanks to months of hands-on training and preparation at a full-scale, mock-up facility," Lehew said. The mock-up was built in the 28,000-square-foot Maintenance and Storage Facility, which once was planned to support the Fast Flux Test Facility.
Workers using the finished tools and equipment for the work came up with dozens of enhancements as they tested them and practiced to process and package the knockout pot sludge, according to DOE.
Now, containers are being filled to go into a second multi-canister overpack. Plans call for a shipment about every two weeks, which should get all the knockout pot sludge moved to central Hanford by mid-September.
That's the last work planned for the Cold Vacuum Drying Facility.
The rest of the sludge will need a new system for removal from the K West Basin. The final design of that system is expected to be completed by the end of September.
An annex is being modified next to the K West Basin for removal and treatment of the remainder of the sludge.
It will be pumped from underwater, engineered containers in the basin into the modified annex, where it will go into casks. The casks will be loaded onto a trailer there to be taken to central Hanford.