Hanford lab analyzes precious samples of highly radioactive waste

By Annette Cary, Tri-City HeraldFebruary 18, 2013 

Hanford's 222-S Laboratory, where some of the nation's most hazardous radioactive material is handled and analyzed, is a mix of contradictions.

Its primary job is to analyze samples of waste left from the past production of plutonium for the nation's nuclear weapons program.

But once a sample of waste is collected from Hanford's underground tanks holding 56 million gallons of radioactive waste, it becomes precious material.

"These are very important, very valuable samples," said Dan Hansen, the lab operations manager for Department of Energy contractor Advanced Technologies and Laboratories, or ATL.

The central Hanford lab is old, dating from 1951 when it was the process lab supporting the REDOX plutonium separations plant. But it has the newest large hot cells in the Department of Energy complex and DOE plans to use the lab for decades to come.

With work at Hanford now focused on environmental cleanup, the lab is one of only two operating nuclear facilities at the site.

And it is the only continuously operating nuclear facility. The other, the 242-A Evaporator, operates only periodically to reduce the amount of liquid waste in some of the tanks to make more space available.

In 70,000 square feet managed by DOE contractor Washington River Protection Solutions, ATL performs about 25,000 inorganic, organic and radionuclide analyses a year at the 222-S Laboratory.

Samples can be very small, almost forensic, like a wipe of difficult-to-reach material between the shells of one of Hanford's underground double-shell tanks. Or they can be large, like the multiple 19-inch-long core samples taken from the sludge and salts in Hanford's underground tanks.

Grab samples of liquid waste also are collected by lowering a jar into an underground tank and then loading it into pigs -- heavy shielded metal containers -- for the trip to the lab. Like all highly radioactive samples shipped to or from the lab, they're packaged like Russian nesting dolls, with containers within containers within containers.

"We bring large bulk containers into this facility and break it down into smaller volumes," said Rob Schroeder, an ATL manager. "We reduce exposure to workers."

The small samples can be analyzed in laboratories under fume hoods rather than inside hot cells.

Work to prepare highly radioactive samples taken from the tanks starts in an addition added to the laboratory complex in 1994, which includes two, 12-foot by 12-foot hot cells.

The 11 hot cells at the 222-S Laboratory also are used for tasks that include testing equipment that will be used at the lab in the vitrification plant under construction using radioactive waste rather than a nonradioactive waste simulant.

Samples of waste are loaded through small portholes and workers standing outside the shielded glass windows of the hot cells use controls to maneuver manipulators to grasp and pick up items inside the hot cells.

On a recent day, David Jackson, an ATL chemical technician, was doing some housekeeping, using a manipulator to wash beakers a couple of inches high that had been used for pH tests. Stacked nearby in the hot cell were crates of glass jars topped with blue lids holding other waste samples. The longer they've been stored, the darker the glass -- discolored by radiation.

Collecting a sample of high-level radioactive waste from the tank farms, where workers don't have the benefit of hot cells, can cost tens of millions of dollars, said Jou Hwang, ATL president. They're stored in case more testing is needed.

Once a year each jar is reweighed and lids made brittle by radiation are replaced.

The equipment in the hot cell must survive the same harsh conditions.

"The challenge with electronic devices in the hot cell is they deteriorate fairly fast because of radiation," Hwang said.

Repackaged samples are taken to the analytical laboratory, where their small size reduces radiation exposure. In addition, the classic radiation protections of time, distance and shielding are relied upon to protect workers.

Work is done as quickly as possible and half-ounce samples are packaged in tungsten carriers weighing about eight pounds to provide shielding.

Workers leave at least 4.5 inches of distance between themselves and samples, using tools such as custom-designed cap removers, tongs and pipettes to do work. Samples may be moved around the laboratory in classic Red Flyer children's wagons to add distance between them and workers.

Employees working with the samples under the hoods wear dosimeter finger rings to monitor radiation.

The samples may be analyzed to make decisions such as whether the contents of two underground tanks may be safely combined and to keep waste in tanks in a safe condition, Schroeder said.

"It's not like C.S.I.," Hansen said. There is no computerized equipment that instantly characterizes samples.

Instead, samples may be dissolved or bathed in an extraction fluid and then analyzed, using any of an array of spectrometers and other equipment. The 222-S Lab has more than 100 pieces of analytical equipment and 156 fume hoods.

Although the laboratory dates to 1951, Washington River Protection Solutions invested $30 million in Recovery Act money into upgrades. Although now a major use of the lab is to analyze waste to safely manage stored waste, in the future it will be needed to make sure the waste meets the chemical, physical and radiological requirements to be treated at the vitrification plant.

Improvements have included a new storage facility, a new administration building, new instruments, an improved ventilation system and replacing the old steam-heat system with electrical heat, providing better conditions for delicate and sensitive instruments.

The computer network that used a DOS operating system was upgraded, along with an analytical system that would not operate with a modern computing system.

When all 56 million gallons of radioactive waste are removed from underground tanks and treated in an estimated four decades from now, the lab still will be operating, under current plans.

"This will be the last facility operating standing," Hwang said. It will be used not only to support work at the vitrification plant, but also may be used to decommission the vitrification plant.

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