Development of nondestructive identification method for material using color X-ray imaging system

摘要

Low-level radioactive wastes generated from nuclear power plants, reprocessing plants or enrichment plants are stored in airtight containers such as drums at sites. Recently, requirements for reducing low-level waste amounts have been increasing due to the limited capacity of temporary waste storage facilities. Volume reduction methods such as incineration for combustible materials or melting metals to make ingots are being developed. It is necessary to identify the material prior to such processing, preferably without opening the package as it contains radioactive substances. X-ray imaging is the most popular and suitable method for nondestructive inspection of waste stored in drums. However, the conventional X-ray transmission imaging method is ineffective for identifying materials unless their thicknesses are known. The dual energy subtraction method emphasizes the differences between materials. It can be applied in the medical field to emphasize the contrast of only soft tissue or that of only bone structure. It was reported that it is used to extract the solder constituent from CSP Boards. However, wide dynamic range of X-ray imaging system is necessary for applying this method to the inspection of waste stored in drums, because it contains miscellaneous materials that vary in terms of size or X-ray absorption.