HANFORD Work has begun with federal economic stimulus money to solve the mystery of what's buried in one the most hazardous burial grounds of the Hanford nuclear reservation.
The 618-10 Burial Ground "received some nasty stuff from the labs in the 300 Area where they did everything done at Hanford but at a small scale," said Larry Gadbois, scientist at the Environmental Protection Agency, a regulator on the project.
The six-acre burial ground includes 94 pipes buried vertically that allowed trucks to drive up and quickly drop radioactive and chemical waste underground. Most were made by removing the tops and bottoms of 55-gallon drums and then welding five of them together to form pipes. The 618-10 Burial Ground also includes 23 trenches.
Many records of what they contain were destroyed in the early 1990s.
Now Washington Closure Hanford and the Department of Energy are trying to determine what they hold using the remaining records and by testing, starting with a method that doesn't require opening or cutting into the vertical pipe units.
"For the safety of the workers going forward, we need to know exactly what's underground," said Cameron Hardy, DOE spokesman.
Information will be used to develop a plan for safely removing the waste from the ground and to determine what waste can be disposed of at Hanford's landfill for low-level waste and what will need to be sent to national repositories elsewhere that handle waste contaminated with plutonium or high-level radioactive waste.
North Wind, recently acquired by CIRI of Alaska, is using $4.4 million in economic stimulus money through a Washington Closure subcontract to check for radiation levels in the burial ground without disturbing its contents.
It started work this summer by using ground penetrating radar to determine exactly where the vertical pipe units were buried in the site, which is about six miles north of Richland near the highway.
More recently, the subcontractor has been pushing narrow steel cylinders into the ground around the vertical pipe units to as deep as 24 feet. Each unit is ringed with four cylinders 6 to 8 inches away, precisely placed to avoid hitting the vertical pipe units even deep underground, said Ron Morris, Washington Closure's subcontractor technical representative.
With many of the cylinders already pounded into the ground, work has begun to lower detectors down the cylinders to take readings at 1-foot intervals. The instruments can detect gamma and neutron radiation and the strength of gamma radiation to allow an educated guess at what might be in the vertical pipe units.
"There is some very highly radioactive material," although it has decayed some in the last half-century, said William Gowey, radiation protection supervisor on the project.
Waste was generated in the Hanford 300 Area just north of Richland where research was done on nuclear fuel development and on the processing of irradiated fuel to remove plutonium for the nation's nuclear weapons program.
From about 1954-63, waste was trucked several miles to 618-10, where it was dropped into the vertical pipe units in gallon and quart containers and 6-ounce paint cans.
Some of the first data from the radiation monitors lowered alongside the vertical pipe units shows some with cesium 137, which likely indicates highly radioactive fuel or pieces of fuel from Hanford reactors. Others have indications of cobalt 60, likely from radioactive reactor parts that failed and then were brought to the 300 Area for testing.
The Department of Energy also believes 618-10 may contain up to 2.2 pounds of plutonium.
Analyzing all the data will take several months, and then a decision must be made on whether intrusive testing is needed to learn more before cleanup work begins.
"The sooner we can get the investigation done, the sooner we can plan and conduct the remediation," Gadbois said.
DOE's goal is to have most of the area near the Columbia River, which includes the 618-10 Burial Ground, cleaned up by 2015. However, Washington Closure plans a slow and deliberate pace at this and the other high-hazard burial ground, 618-11, that may take longer.
-- Annette Cary: 509-582-1533; email@example.com