The growing volumes of Low-Level Radioactive Waste (LLW) generated by the nuclear power plant operations require better immobilization technique that can overcome the limitations of conventional Portland cement-based matrices. This work reports on cold immobilization technique for conditioning of simulated radioactive incinerated ash classified as LLW. This method facilitates effective solidification and immobilization of simulated incinerated ash waste using binding materials comprising limestone, gypsum, and sodium silicate. Uniaxial compaction was utilized to produce composite pellets under ambient and low temperature conditions. The Taguchi method in Minitab® 22.4 was employed to optimize mix design parameters. The impact of binder composition and compaction pressure on compressive strength of composite pellets were systematic evaluated. The developed composites achieved compressive strengths of up to 40 MPa, surpassing lower bound of international waste acceptance criteria. A waste volume reduction of approximately 71.75% was obtained by incorporating 37.71 wt.% of binder material and 62.29 wt.% simulated incinerated ash, followed by compaction at 625 MPa. Sodium silicate concentration and compaction time were identified as key factors affecting compressive strength, while it is also noticed that strength of composite pellets also increased with curing age. SEM analysis showed the development of dense, stable matrices. Moreover, selected composites were subjected to gamma dose of 57 Gy at irradiation rate of 475 mSv/h over five days. These composites retained most of their compressive strength, these findings represent reasonable radiation stability and mechanical durability under accelerated testing conditions. The overall results demonstrate that binder-based immobilization at ambient temperature presents a durable, efficient, and environmentally sustainable method for LLW management, for storage and disposal.
 

low level radioactive waste,cold immobilization,volume reduction,compressive strength.