An overview of radioactive waste management technology development current status and trends

Led by the developing federal and state regulatory standards governing the nuclear industry, radwaste management technology has been gradually evolving for approximately four decades. These standards have become increasingly stringent in the last few years. To comply with these standards, the pace of development in radwaste management technology has accelerated significantly. An overview of the current state of the art in radwaste management technology in the United States is presented in this paper, with an attempt to analyze its future trends. The overview covers the legally defined radwaste categories, including high-level waste (HLW), spent nuclear fuel (SNF), transuranic (TRU) waste, and low-level waste (LLW). Over 95% (by volume) of the HLW in existence in the United States is the result of defense-related fuel reprocessing activities under the jurisdiction of the Department of Energy (DOE). Consequently, major efforts are being made by the DOE in developing HLW management technologies to ensure its safe, long-term disposal and isolation. Current emphasis for HLW solidification/immobilization is placed on the vitrification process, with the crystalline ceramic form process as an alternative. Most of the SNF is presently being accumulated in storage pools at individual commercial power reactor sites. The SNF storage space in many of the power plants, however, is becoming scarce. Several different designs of dry storage facilities are being developed by a few nuclear power plants to provide interim storage [e.g., Surry (Virginia Power), an and H. B. Robinson (Carolina Power and Light)]. The ultimate long-term isolation technology of SNF will be disposal in one or more deep geologic repositories. The location of such a repository, however, has not yet been decided. Recently (November 1989), the Monitored Retrievable Storage (MRS) Commission appointed by the U.S. Congress recommended that a federal emergency storage (FES) facility (with a capacity of 2000 metric tons of uranium) and user-funded interim storage (UFIS) facility (with a 5000-metric ton uranium capacity) be authorized for construction to provide safe interim storage of SNF. Like HLW, the major portion of TRU wastes have been generated by defense-related activities. Because this type of waste includes TRU-contaminated bulky equipment (such as glove boxes), size reduction is one of the key steps in its processing. Liquid/sludge TRU wastes require concentration and solidification. The existing "suspect" TRU wastes are stored in shallow-land burial sites (prior to establishment of the 1970 policy). Since establishment of the 1970 policy, the TRU wastes have been in retrievable storage at individual DOE facilities. The current plan is for those wastes in retrievable storage adn those newly-generated to be transported to and emplaced in a prototype geologic repository (waste isolation pilot plant, or WIPP) for long-term isolation, assuming that the WIPP will have successfully completed a five-year test phase. Low-level waste (LLW), which accounts for more than 80% of the total volume of radwastes generated, comes in a variety of forms and is generated by widely different sources. The processing method, therefore, varies with the type and the nature of the LLW. The common emphasis, however, is on volume reduction, including evaporation and solidification (liquid/slurry), incineration (combustibles), and compaction. The major disposal technology for solid LLW in the past has been shallow-land burial. At DOE facilities, liquid LLW is normally stored in underground tanks prior to solidification. Among the key issues to be emphasized are the development of new disposal facilities nationwide and of improved burial site designs.