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Leaching Behaviour of Sodium Carbonate-Activated Slag/Ash Matrices Encapsulating Spent Nuclear-Grade Ion Exchange Resins
Spent ion exchange resins are a waste that is generated in the operation of nuclear power plants. These resins are usually managed by their immobilisation in cementitious matrices, specifically based on Portland cement. In this context, alkali-activated cements (AACs) emerge as a promising and more sustainable option for resin immobilisation.
This study evaluates the leaching behaviour of AACs containing spent resins (7.5 wt.% by binder). These resins are saturated in a solution consisting of boric acid, cobalt chloride, nickel nitrate, strontium chloride, cesium chloride, and copper sulphate. The AAC evaluated is based on blast furnace slag and fly ash. Sodium carbonate (8 wt.%) is used as an alkaline activator as its utilisation reduces the environmental footprint of the cementitious material. This matrix is compared with a reference Portland-based matrix currently employed for resin immobilisation. To evaluate the confining capacity of the systems a semi-dynamic leaching test is carried out according to ANSI/ANS 16.1-2019.
Results indicate that the reference matrix has a higher calcium leaching ratio (12 wt.% by binder) compared to the AAC (3 wt.%), suggesting a potential higher gel degradation of the reference system. The AAC matrix also shows improved strontium retention compared to the reference, whereas the reference matrix exhibits higher boron retention. Additionally, after a 90-day leaching test, AAC demonstrates significantly better mechanical development than the Portland cement-based reference. Micrographs show a region affected by the leachant of around 200 µm, however, EDX results indicate no compositional alteration of the gel in that region.
Leaching Behaviour of Sodium Carbonate-Activated Slag/Ash Matrices Encapsulating Spent Nuclear-Grade Ion Exchange Resins
Spent ion exchange resins are a waste that is generated in the operation of nuclear power plants. These resins are usually managed by their immobilisation in cementitious matrices, specifically based on Portland cement. In this context, alkali-activated cements (AACs) emerge as a promising and more sustainable option for resin immobilisation.
This study evaluates the leaching behaviour of AACs containing spent resins (7.5 wt.% by binder). These resins are saturated in a solution consisting of boric acid, cobalt chloride, nickel nitrate, strontium chloride, cesium chloride, and copper sulphate. The AAC evaluated is based on blast furnace slag and fly ash. Sodium carbonate (8 wt.%) is used as an alkaline activator as its utilisation reduces the environmental footprint of the cementitious material. This matrix is compared with a reference Portland-based matrix currently employed for resin immobilisation. To evaluate the confining capacity of the systems a semi-dynamic leaching test is carried out according to ANSI/ANS 16.1-2019.
Results indicate that the reference matrix has a higher calcium leaching ratio (12 wt.% by binder) compared to the AAC (3 wt.%), suggesting a potential higher gel degradation of the reference system. The AAC matrix also shows improved strontium retention compared to the reference, whereas the reference matrix exhibits higher boron retention. Additionally, after a 90-day leaching test, AAC demonstrates significantly better mechanical development than the Portland cement-based reference. Micrographs show a region affected by the leachant of around 200 µm, however, EDX results indicate no compositional alteration of the gel in that region.
Leaching Behaviour of Sodium Carbonate-Activated Slag/Ash Matrices Encapsulating Spent Nuclear-Grade Ion Exchange Resins
RILEM Bookseries
Ferrara, Liberato (Herausgeber:in) / Muciaccia, Giovanni (Herausgeber:in) / di Summa, Davide (Herausgeber:in) / de Hita, M. Jimena (Autor:in) / Criado, María (Autor:in)
RILEM Spring Convention and Conference ; 2024 ; Milan, Italy
Proceedings of the RILEM Spring Convention and Conference 2024 ; Kapitel: 52 ; 460-468
RILEM Bookseries ; 56
07.11.2024
9 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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