Iodine immobilization: Development of solidification process for spent silver-sorbent using hot isostatic press technique

This paper deals with the development of the production process. Silver-sorbents loaded with inactive iodine (I2) were prepared for HIP treatments. Although several types of alumina are originally present in the alumina based materials, they were found to be transformed to corundum after the HIP treatment. Optimization of the HIP process conditions was carried out. The effects of the major parameters on the process were investigated. Scanning electron microscope observations (SEM) confirmed that iodine was confined as AgI in the alumina matrix after the HIP treatments. A certain number of voids (void ratio: 10-15%) coexisted. Reduction of voids was further investigated and it was established that high temperature and vacuum pretreatment of iodine loaded silver-sorbents before the HIP treatment could significantly reduce void ratios to less than 5% in the solidified bodies. A simulation program for the HIP was developed to predict the size and relative density of the scale-up solidified body.