Abstract
The paper presents a methodology for determining the thermal stability of the “LRW–sorbent” system, intended to assess the feasibility of converting liquid radioactive waste (LRW) into a non-flowing state using sorbent materials. Natural and synthetic sorbents of different origins were used as study objects, including perlite, perlite sand M-100, vermiculite, agrovermiculite, a synthetic polymer sorbent (“superabsorbent”), and a mineral sorbent developed at Shakarim University. The sorbents were tested for freeze–thaw resistance (50 cycles at ±40 °C) and long-term thermal stability (600 hours at +50 °C). It was found that perlite-based sorbents exhibit the most favorable combination of properties, combining high absorption capacity with resistance to thermal cycling. The mineral sorbent developed at Shakarim University (“S-sorbent”) demonstrated minimal changes in mass and structure; however, its sorption capacity is lower than that of perlite. Vermiculite and agrovermiculite showed mechanical stability but insufficient liquid retention capacity, while the superabsorbent was excluded from further consideration due to structural degradation under thermal exposure. The obtained results confirm the applicability of the proposed methodology for predicting the behavior of “LRW–sorbent” systems under temperature conditions typical for storage. The results may be used to substantiate technologies for the management of LRW from the BN-350 reactor facility.