Year
1990
Abstract
During the last two decades, the Department of Energy's Office of Safeguards and Security (DOE/OSS) has supported the research and development of safeguards systems analysis methodologies and nondestructive assay (NDA) technology for characterizing, monitoring, and accounting nuclear materials. This paper discusses methodologies and NDA instrumentation developed by the DOE/OSS program that could be applied in the Environmental Restoration Program. NDA instrumentation could be used for field measurements during site characterization and to monitor nuclear materials, heavy metals, and other hazardous materials during site remediation. Systems methodologies can minimize the expenditure of resources and help specify appropriate combinations of NDA instrumentation and chemical analyses to characterize a variety of materials quickly and reduce personnel exposure in hazardous environments. A training program is available to teach fundamental and advanced principles and approaches to characterize and quantify nuclear materials properly and to organize and analyze measurement information for decision making. These courses use a variety of specialized NDA instruments, many of which have been transferred to the private sector and are commercially available. The ability to characterize the overall volume and distribution of materials at a waste site is difficult because of the inhomogeneous distribution of materials, the requirement for extreme sensitivity, and the lack of resources to collect and chemically analyze a sufficient number of samples. Using a systems study approach based on statistical sampling, the resources necessary to characterize a site can be enhanced by appropriately combining in situ and field NDA measurements with laboratory analyses. Active neutron NDA systems allow samples ranging in size from a few grams to several hundred kilograms to be assayed to levels below lOOnCi/g. These systems also can detect and quantify a range of heavy metals and low-Z materials such as chlorine, cadmium, beryllium, and nitrogen based on neutron capture gamma-ray analysis. Heavy metals can be characterized using x-ray fluorescence and densitometry techniques. NDA in situ and portable field systems make possible real-time measurements for delineating the boundaries of waste sites. These portable systems also allow continuous on-line analysis of small samples as well as the monitoring of large volumes, such as materials moving on a conveyor belt during site remediation. Recent developments have demonstrated the capability for unattended, remote operation of NDA systems that permit continuous monitoring and collection of data. This information is stored in large databases where pattern recognition and artificial intelligence techniques can be used to automate and improve analysis of the data.