 Gate system sorts out "clean" dirt DOE's Office of Science and Technology (OST) is funding the Accelerated Site Technology Deployment program, formerly known as the Technology Deployment Initiative (see back issues of Initiatives). Projects in the program promise to reduce the cost of environmental management and accelerate cleanup throughout the complex. One project currently funded under the program is the Segmented Gate System. The first deployment of the Segmented Gate System (SGS) since its acceptance into the Accelerated Site Technology Deployment (ASTD) program was completed at Sandia National Laboratories in March 1998. By August 1998, three more deployments are scheduled for completion at Pantex in Texas, Tonapah Test Range in Nevada, and Ashtabula in Ohio. A total of seven deployments of SGS are planned during its time as an ASTD project. Multisite deployment is a primary goal of the ASTD program. About SGS The system works by spreading a 1/2- to 2-inch layer of excavated soil on a conveyor belt. The belt passes under a series of sensors that measure levels of radionuclides. Based on the sensor readings, a computer-controlled sorter separates the soil by inserting the appropriate gate into the stream of soil falling off the end of the conveyor. Contaminated soil is channeled through a diversion gate to a contaminated diversion conveyor. It is ultimately packaged and transported for disposal. Clean soil is channeled to the clean diversion conveyor and goes back to the site. The computer software that directs the sorting is a key component in the system. The recovery of clean soil varies from 50 to 99 percent depending on the type of soil and contamination. Because of the reduction in waste volume, the projected cost savings with SGS are greater than $50 million for the ASTD deployments alone. Before being accepted into the ASTD program, SGS had been successfully demonstrated at several DOE sites, including Los Alamos National Laboratory, the West Valley Demonstration Project in New York state, and the Savannah River Site. The system was initially developed for use at a Department of Defense site, Johnston Atoll—a coral island in the Pacific, where it has been in use since 1990 to achieve volume reduction rates of 84 percent. SGS as an ASTD
project According to Maynor, "ASTD is definitely a program that's needed in DOE to bridge the gap in getting technologies into the field." Maynor also thinks the requirement that ASTD projects have funding support from both technology developers and technology users at a site makes sense. He says, "It provides an incentive for using the technology and opportunity for proof of performance." Advanced sensors developed and evaluated by DOE's Office of Science and Technology have been tested with SGS. OST's focus was on adapting the sensors to achieve a lower sensitivity for plutonium-contaminated soils. ASTD funding covers mobilizing SGS at each site and making sensor and other modifications to ensure the system will work at the site. Then, ASTD covers processing the first 1,000 cubic yards of soil. Additional processing costs are the responsibility of the site. Finally, the ASTD program funding covers disassembling the system so it can be moved and set up at another site. ASTD funding from OST is also supporting visits from planned users at one site to view the deployment at another. An important part of the ASTD program is the requirement for the technologists to collaborate with stakeholders and regulators before the deployments. This is being done in part through work with the Interstate Technology and Regulatory Cooperation (ITRC) Work Group. ITRC is a coalition of state environmental regulatory agencies that works to improve the acceptance and interstate deployment of innovative environmental technologies. Deployment at
Sandia For more information about Thermo NUtech or SGS, contact: Jeff Brown, Vice President or Scott Rogers, SGS Project Manager |
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SGS
mechanically sorts radioactively contaminated soil into a
clean stream and a contaminated stream, reducing the
volume of waste to be packaged, transported, and disposed
of. According to a 1994 DOE report, sites throughout the
DOE complex contain an estimated 73 million cubic yards
of soil containing heavy metals, primarily radionuclides.
These heavy metals include uranium, thorium, cesium,
strontium, and plutonium. The baseline for handling the
soil is excavation and disposal without sorting, which
can cost $200– $1,000 per cubic yard. The costs vary
depending on the radionuclide and whether disposal is on
or off site. Disposal is chosen over treatment because
proven treatment processes are not yet available.