Microwave processsing of glass-ceramic material to encapsulate chloride waste from molten salt reprocessing of spent nuclear fuels

Abstract

With ANSTO's entry into EUROPART, a project that is co-funded by the European Commission, regarding the study of a new class of waste forms is being investigated. The wastes are a result of reprocessing spent nuclear fuel using pyrometallurgical techniques to electrolyse the spent fuel elements and to recover the unused plutonium and uranium for recycling in other forms of fuel elements. The waste resulting from this work is a mixture of various chlorides that contain radiotoxic isotopes like 137Cs and 90Sr as well as minor actinides like americium, curium and neptunium, which can also be recovered and either disposed of as a waste, or redirected for transmutation and subsequently disposed. The waste is a highly conductive material, so it lends itself very well for processing with such technologies as microwaves and radio-frequencies. We propose to develop a process using microwaves to convert this waste into a durable waste form. A test composition of the waste and additives chosen to form a glass ceramic is used. The approach for the composition design is the same as that used to design SYNROC (SYNthetic ROCk). The studies were conducted at the microwave laboratories of University of Modena and Regio Emilia as well as ENEA in Bologna, Italy. Here we report the preliminary experiments and the results obtained, highlighting the problems and how we might deal with them.