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Annette Cary / Tri-City Herald (TNS)

Before the end of the summer, a significant risk of radioactive contamination of the Columbia River at the Hanford nuclear site is to be eliminated.

Hanford workers have begun pumping contaminated water from the last pool of the nuclear reservation’s nine reactors on the Columbia River.

“This action will eliminate the risk of contaminated water seeping into groundwater about a quarter mile from the Columbia River,” said Andy Wiborg, the Department of Energy’s deputy director for river and plateau cleanup.

“Removing contaminated water from this basin is a critical step in our risk reduction mission,” he said.

At the Hanford Nuclear Reservation near Richland in eastern Washington, about two-thirds of the plutonium for the nation’s nuclear weapons program was produced from World War II through the Cold War.

After the uranium fuel had been irradiated, it was pressed out of the back of the reactors into inner pools for cooling and, after the end of the Cold War, was stored in pools partly unprocessed. The five-meter-deep water in the pool protected the workers who stood on grates above the pool to transport the fuel into storage containers.

The cooling pools of seven of the reactors have been demolished, and the pool of Reactor B, the nation’s first fully operational nuclear reactor, is preserved as part of the Manhattan Project National Historical Park.

But the 1.2 million gallon pool of the K-West reactor, built in the 1950s, still contains contaminated water that shields the radioactive debris in the pool.

“EPA-approved work on the 100K West Basin began in the 2000s to remove spent nuclear fuel,” said Roberto Armijo, remediation project manager at the Environmental Protection Agency (EPA), which is in charge of the work at Hanford.

Radioactive sludge was stored in the reactor pool

The K West and K East reactor pools were last used after storing irradiated fuel from the N reactor that was no longer processed after the end of the Cold War. Before the fuel was removed in 2004, it corroded underwater and contributed to a highly radioactive sludge.

In 2019, the last of the sludge was removed, and the next big task is to drain the water to reduce the dangers posed by the pools.

First, the nearby reactor pool of the K-Ost reactor was emptied.

In June, the first tanker truck carrying pool water left the K-West reactor.

So far, about 400,000 gallons have been pumped out of the basin, the equivalent of six private swimming pools, said Heather Dale, Hanford Energy Department’s deputy director for the river and plateau. About 60 tanker trucks have been filled with basin water.

Workers for DOE contractor Central Plateau Cleanup Co. spent about two years preparing to divert and filter water from the K West Basin.

They moved radioactive waste that had been in the basin since the 1950s into underwater containers and sorted it. The waste included canisters once used to store fuel, canister racks, pumps, hoses, hand tools, construction materials and components of a water treatment plant.

The workers stood on the grate above the water and used long-handled tools and underwater cameras to do their work. Among other things, they placed some of the most radioactive debris into vertical steel pipes in the basin.

They also installed a system to pump out and filter the contaminated water before loading it into tanker trucks.

The filter system removes particles and also uses an ion exchange system to remove radioactive cesium and strontium from the water. The resin originally used in the ion exchange system did not work well, the Defense Nuclear Facilities Safety Board said in January.

By the summer, however, improvements had been made that allowed the water to meet standards and be trucked to downtown Hanford, where a small amount of remaining contaminants are removed at the wastewater treatment plant.

Reactor pool is grouted

“The work of multiple teams to characterize, sort and classify the debris in the basin has enabled us to begin removing the water and preparing to grouting the basin,” said Mike Kruzic, who leads reactor-area closure projects for the Department of Energy contractor.

Once the water is removed, the pool and vertical pipe casings are filled with concrete-like mortar, which is allowed to cure for a year or two. After the pool roof is removed, a drilling rig with a drill can be brought in to mix the waste in the casings with mortar.

It is a technology that has previously been developed and successfully used at one of the worst underground radioactive waste storage sites in Hanford, the 618-10 Burial Ground.

Some of the contents of the vertical tubing units in the K-West reactor pool may need to be sent to the National Transuranic Radioactive Waste Repository in New Mexico for disposal.

The remaining mortar, including the mortar used to fill the pool, as well as the walls and floor of the pool, will be crushed by excavators and taken to a sealed landfill in Hanford for disposal.

“Once dewatering and grouting are completed, the next steps of the project will include soil remediation and encapsulation of the 105-K West reactor building,” Armijo said.

Contaminated water leaked into the ground from one of the connecting points of the K-East reactor pool. However, there is no evidence of significant leaks in the K-West reactor pool.

The final step in the coming years will be to temporarily encase the K-East reactor in a steel cocoon to allow radiation in its core to drop to lower levels over 75 years before a permanent solution is tackled.

The K-West reactor will be the last shielded reactor at Hanford, and the tripartite agreement requires completion of work by September 2032.

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