TECHNOLOGIES IN USE AND IN DEVELOPMENT FOR SURPLUS FACILITY DECOMMISSIONING AND RECYCLING UNDER ENVIRONMENTAL RESTORATION

摘要

The mission of the U.S. Department of Energy's (DOE) Environmental Restoration Program is to ensure that risks to human health and safety and to the environment, posed by contaminated inactive waste sites and surplus facilities, are either eliminated or reduced to prescribed, safe levels. The program is concerned with all aspects of assessment and remediation activities where sites and facilities are no longer associated with active nuclear-related production or research operations. Remedial action comprises assessment and remediation of inactive waste sites and correction of a release or spill problems. Decommissioning entails the assessment, decontamination, reuse, or dismantlement of surplus contaminated facilities that are no longer active. DOE has identified more than 700 surplus contaminated facilities requiring decommissioning, and the inventory of facilities requiring decommissioning continues to increase. These facilities contain radionuclide, hazardous, mixed and special contaminants. Some facilities were designed for ease of maintenance during operations and generally allow for efficient and economic decommissioning. Many facilities, however, were not designed for ease of maintenance or were designed before the techniques for contamination prevention were available and are usually much more difficult and costly to decommission. These facilities require a variety of decommissioning methods, including characterization, decontamination, dismantling, segmentation, and demolition. Decontamination involves the removal of contamination from surfaces of facilities or equipment by washing, heating, chemical or electrochemical action, mechanical cleaning, or other techniques. Dismantling refers to the physical disassembly of equipment in buildings or other areas while segmenting refers to cutting apiece of equipment or structure into smaller parts using some type of blade, explosive, or other means before removal. Demolition includes activities performed to completely raze a building or structure, reducing it to rubble or easily manipulative pieces. In addition, for areas that are inaccessible or are unsafe for occupancy, remote handling equipment and operations are utilized in decommissioning. This paper describes recent experience with and development initiatives of three categories of decommissioning technologies: concrete decontamination, dismantlement and handling, and metal recycling. Six recent decommissioning projects are used to highlight the use of, and challenges overcome with, current technologies in these three categories. These projects are Plant 7 at Fernald, Ohio; the Electrochemical Machining Area of the Alpha-4 Production Facility at the Y-12 Plant, Oak Ridge, Tennessee; the Special Metallurgical Building at the Mound Production Plant, Ohio; the Experimental Boiling Water Reactor at Argonne National Laboratory-East, Illinois; the Animal Hospital Buildings at the Laboratory for Energy-related Health Research, California; and the Hanford 185/190-B Building in Hanford, Washington.