Researchers at the Pacific Northwest National Laboratory have created the Pit Viper, a remotely operated cleanup system for personnel working in nuclear tank waste equipment pits.
It is estimated that radiation exposure to personnel working in highly contaminated nuclear tank waste equipment pits may be reduced by as much as 75 percent.
‘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,’ said 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.’
After testing the Pit Viper will be employed by the US Department of Energy under the Hanford River Protection Program, which requires the repair and refurbishment of hundreds of equipment pits on the nuclear site.
More than 600 tank waste equipment pits are located adjacent to Hanford’s 177underground 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, plant is complete in 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 immobilised for disposal.
These equipment pits are contaminated and must be inspected, cleaned, decontaminated and refurbished before the transfer of the tank waste can begin.
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,’ said 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 manoeuvred 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.