THERMAL ANALYSIS AND IMMOBILISATION OF SPENT ION EXCHANGE RESIN IN BOROSILICATE GLASS

Abstract

The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve it through minimizing the volume and cost by reducing the amount of glass used without compromising the safety of any leakage from the radioactive waste form. The immobilization of the spent resin (NRW-40) in borosilicate glass was investigated to meet the acceptance criteria for disposal of nuclear waste. The organic mixed bed resin in granular form was used as a waste target. The analysis of surrogate resin doped with radioactive and non-radioactive cesium (Cs) and cobalt (Co) was carried out to investigate their thermal and chemical properties and their compatibility with an alkaline borosilicate glass. Thermal analysis indicates that the structural damage caused by 1 mSv gamma radiation to the radioactive resin has altered its properties in comparison with the non-radioactive resin, using the same amount of cesium (8.88 wt%) and cobalt (1.88 wt%) in both resins. The immobilization of residue shows that the excess sulfur in the residue caused phase crystallization in the final glass matrix. It was found that the volatilization of Cs-137 and Co-60 from the successful radioactive resin-glass matrix (HG3-IER-500) were more than that in the non-radioactive resin-glass matrix (HG-3-IEX-500). The study demonstrates comprehensive experimental and analytical work and shows that it is possible to minimize the volume of the waste while keeping the required safety levels; however, further research needs to be carried out in this area.