Vitrification development plan for US Department of Energy mixed wastes

Abstract

This document is a general plan for conducting vitrification development for application to mixed wastes owned by the U.S. Department of Energy. The emphasis is a description and discussion of the data needs to proceed through various stages of development. These stages are (1) screening at a waste site to determine which streams should be vitrified, (2) waste characterization and analysis, (3) waste form development and treatability studies, (4) process engineering development, (5) flowsheet and technical specifications for treatment processes, and (6) integrated pilot-scale demonstration. Appendices provide sample test plans for various stages of the vitrification development process. This plan is directed at thermal treatments which produce waste glass. However, the study is still applicable to the broader realm of thermal treatment since it deals with issues such as off-gas characterization and waste characterization that are not necessarily specific to vitrification. The purpose is to provide those exploring or considering vitrification with information concerning the kinds of data that are needed, the way the data are obtained, and the way the data are used. This will provide guidance to those who need to prioritize data needs to fit schedules and budgets. Knowledge of data needs also permits managers and planners to estimate resource requirements for vitrification development. Vitrification has already been developed for high-level waste and other types of radioactive and industrial waste. Based on this experience, development for mixed waste should also be feasible. One distinguishing aspect of mixed waste, however, is variability and uncertainty in composition. Production of a glass acceptable for land disposal will require some knowledge of the waste composition so that appropriateglass-forming chemicals can be added where necessary. Process safety will also be a factor when vitrifying unknown waste materials. Another special feature of mixed waste is that it consists of regulated hazardous materials as well as radionuclides. Vitrification development should thus result in equipment systems and process chemistry flowsheets that satisfy regulatory requirements for waste form product consistency, product quality, worker safety, equipment perfo.rmance,and environmental discharges. The required product quality is not yet defined beyond certain minimal limits. Through vitrification development, the glass waste form can be tailored to any desired level of quality.