Progress on experimental protocols, formulation of conditioning materials and performance assessment for the direct conditioning of RLOW

WP5 proposes to investigate a direct route for the conditioning of Radioactive Liquid Organic Waste (RLOW). After a short state-of-the-art, which highlights the high potential of alkali-activated materials (AAM) for organic liquid encapsulation, this article presents the main findings of the partners involved in Task 5.3 (NUCLECO/SOGIN, NNL/USFD, CIEMAT, POLIMI, SCK CEN, KIPT, RATEN) to this date. Other Tasks relate to WP management (T5.1), RLOW inventory (T5.2) and durability assessment (T5.4 not started yet). Task 5.3 (T5.3) aims to design reference formulations of conditioning materials for the immobilization of RLOW, prior to Task 5.4, which focuses on the durability assessment of conditioned RLOW by the direct route. Since the start of PREDIS, the partners in T5.3 have proposed varied AAM formulations, based on metakaolin, blast furnace slag, volcanic tuff or their mixes as alumino-silicate solid precursors. The latter are alkali-activated with NaOH, KOH or metasilicate (sodium or potassium based). Varied RLOW are incorporated in the AAM, the most viscous and chemically simple RLOW being those with the greatest incorporation rate. For highly fluid RLOW (e.g. TBP, kerosene or scintillating cocktails), the use of a surfactant proves necessary. Optimizations of the RLOW/AAM mixes are still on going to this date, with already very promising preliminary results.