More scraps of irradiated reactor fuel have been found in Hanford's K West Basin, where it was stored at the end of the Cold War.
The three newly discovered scraps -- broken off of uranium fuel rods -- are small, but highly radioactive.
"The significance comes down to worker protection," said Tom Teynor, Department of Energy project director for the K Basins Closure Project. "We do not want them unknowingly exposed to pieces of fuel. They are high-dose items."
The last of the known fuel was removed from the basin attached to the K West Reactor last year. Work has started to deactivate the Cold Vacuum Drying Facility, which had been used to prepare fuel and scrap fuel from the K Reactor basins for storage in central Hanford's Canister Storage Building.
The additional fuel scraps were discovered with the help of new high-definition color TV cameras and monitors, and it is possible that more scraps yet may be discovered, Teynor said.
The cooling basins attached to the K East and K West reactors were used to hold irradiated fuel at the end of the Cold War that had not been processed to remove plutonium for the nation's nuclear weapons program.
Between 2000-04, about 2,300 tons of irradiated fuel were removed from the K Basins and taken to central Hanford. Removing the fuel removed 95 percent of the radioactivity from the areas along the river where nine reactors operated.
But left in the basins was radioactive sludge formed from corroding fuel, dust and bits of concrete. Hidden in the sludge were more fragments of irradiated fuel, which were gathered and temporarily stored in containers in the K West Basin, shielded by 17 feet of water to protect workers.
In addition, stray fuel pieces and fragments were found when debris burial grounds were dug up near reactors. That fuel also was stored in the K West Basin, along with containers of radioactive sludge vacuumed up in both basins.
The last of that stored fuel was removed from the basin last year, and on May 1 workers gathered to watch the last shipment of known irradiated fuel leave for the Canister Storage Facility.
More recently, workers were measuring the depth of residual sludge in the K West Basin that remains after the basin's underwater floor has been vacuumed several times.
The first scrap was found just outside what workers call the "weasel pit," an area where equipment and fuel suspected of being cracked or damaged were placed for inspection. The area had been passed over several times, but by chance, light reflected off the fuel scrap, Teynor said.
Workers started looking for more and found two additional pieces. The largest measured 1.5 inches by 0.5 inch and the others were about 0.5 inch by 0.5 inch. The scraps would not have been visible with the former black and white video system and lighting, he said.
An inspection plan has been developed to sample more areas to check for additional scraps.
The three fuel pieces have been placed in a canister in the west part of the basin. If any more fuel scraps are found, including among the equipment still in the basin, they will be stored there also.
After fuel pieces first were found in reactor burial grounds in 2004, Washington Closure Hanford was designing a dry storage cask for them. Those efforts ended when plans switched to store the pieces underwater temporarily in the K West Basin.
With the Cold Vacuum Drying Facility being deactivated, DOE's contractor for K Basin work, CH2M Hill Plateau Remediation Co., will continue development of the dry storage cask, Teynor said.
The fuel scraps are not expected to be removed until after sludge held in containers in the basin is removed.
The K East Basin already has been demolished and no fuel scraps were found in it.
The Environmental Protection Agency has been notified that fuel scraps have been found in the K West Basin and is waiting to see if any more are found, said Rod Lobos, an EPA engineer.
-- Annette Cary: 582-1533; firstname.lastname@example.org; Twitter: @HanfordNews