Abstract
Saline liquid radioactive waste (LRW) can be generated during the operation and decommissioning of nuclear facilities, requiring safe treatment and long-term isolation. Conventional treatment methods require high energy consumption and complex infrastructure. For facilities with large accumulated inventories of LRW, such as the BN-350 reactor plant, low-energy approaches enabling conversion of waste into a non-flowable state are highly relevant. Sorption immobilization using porous mineral sorbents represents a promising option; however, its practical implementation requires a quantitative description of kinetically limited sorption and subsequent moisture removal processes. In this work, two complementary computational modules were sequentially developed. At the first stage, a mathematical description of water sorption from an LRW solution by expanded perlite M100 was formulated based on a hybrid model that accounts for temperature dependence and salt precipitation during solution concentration. At the second stage, a two-dimensional model of diffusion-controlled dehydration of the “perlite-salt precipitate” system was implemented using numerical simulation and validated against the results of two independent laboratory experiments. The obtained results confirm the applicability of sorption immobilization as a low-energy and technologically simple approach for the treatment of large volumes of LRW, while the developed model can be used to estimate processing timeframes and support process scale-up for industrial implementation.