Silica alcogels for possible nuclear waste confinement — A simulated study

A new method for possible incorporation of nuclear wastes has been attempted here by using silica alcogels as a host precursor for confinement. The large pore volume of the silica alcogel is used as a sponge to incorporate chemical species. Neodymium nitrate is used as a simulant for high level waste. The alcogels have been immersed in 5, 10, 20 and 30% neodymium nitrate solution and the resulting alcogels are dried under controlled conditions at 70 °C. The bulk density of the gels increases on absorption of neodymium nitrate. The BET analysis shows a decrease in surface area and total pore volume as the percentage of neodymium nitrate is increased. On sintering the gels at 1200 °C neodymium was confined which was confirmed by negative leachability. The percentage of loading has been found out by calculating the difference in weight of the neodymium incorporated gel before and after incorporation of neodymium. XRD studies of the sintered samples reveal the formation of neodymium silicates.