Pit Viper takes bite out of worker radiation exposures
June 05, 2001
The 586 square mile Hanford site in southeastern Washington State produced plutonium for the nation's national defense effort for more than 50 years,
RICHLAND, Wash. –
Radiation exposure to personnel working in highly contaminated nuclear tank waste equipment pits may be reduced by as much as 75 percent thanks to the Pit Viper, a remotely operated cleanup system unveiled today by the Department of Energy's Pacific Northwest National Laboratory.
The most dose-intensive work under Hanford's River Protection Program is the repair and refurbishment of hundreds of equipment pits on the nuclear site. The overall concept of the Pit Viper system is to minimize worker exposure in these high radiation zones through the use of remote technology applications.
"It is anticipated that the remotely operated Pit Viper system can achieve a 50 to 75 percent reduction in radiation exposure as well as significant improvements in operational processes," says Sharon Bailey, Pit Viper project manager at PNNL. "It's simple, but very effective technology based on commercially available components performing multiple tasks. The entire process will be much safer and more efficient than ever before."
DOE's Office of Environmental Management provided technology development funding for the Pit Viper program via the Office of Science and Technology's Tanks Focus area and the Robotics Crosscut Program. PNNL is working with CH2M HILL Hanford Group, the tank waste management contractor at Hanford, Oak Ridge National Laboratory and commercial equipment suppliers to develop, demonstrate and deliver the Pit Viper for Hanford use.
More than 600 tank waste equipment pits are located adjacent to Hanford's 177 underground storage tanks near the nuclear site's central plateau. The rectangular concrete pits lie below ground and contain valves and pipe couplings designed to allow transfer of highly radioactive waste from one underground tank to another. This waste transfer will be essential once construction of Hanford's vitrification, or glassification, plant is complete around 2007. Millions of gallons of liquid radioactive waste will be transferred through miles of underground piping and numerous equipment pits to be treated and immobilized for disposal.
These equipment pits are contaminated and must be inspected, cleaned, decontaminated and refurbished before the transfer of the tank waste can begin. Workers must repair or remove equipment within the pits, conduct radiation mapping or characterization, remove debris, repair wall cracks, and clean, prep and paint walls.
The Pit Viper uses a hydraulic manipulator arm to perform these tasks. "The arm is capable of lifting 200 pounds while fully extended. It is operated remotely from a console in a control trailer located up to 200 feet away from the equipment pit," says Bailey. "The operators work in a clean, safe environment while viewing cleanup activities on television monitors captured by four cameras."
The manipulator arm is mounted on a backhoe that is maneuvered adjacent to an equipment pit. A variety of tools that attach to the manipulator's gripper are available to perform the many cleanup, repair and maintenance tasks.
PNNL currently is testing the Pit Viper system in a non-radioactive environment at DOE's Volpentest HAMMER Training and Education Center in north Richland. Deployment in the field is anticipated this summer after which the system will be turned over to CH2M HILL Hanford Group.
Tags: Environment, National Security, Environmental Remediation