Geopolymer-Based Solidification/Stabilization of Radioactive Wastes

The aim of this work was to evaluate the possibility to solidify radioactive expanded clay balls or radioactive sludge originating from the decommissioning of NPP V1 in Jaslovské Bohunice (Slovak Republic) into the geopolymer matrices. The radioactive wastes (RAW) in the proportion of 0 wt.%, 20 wt.%, 25 wt.%, and 30 wt.% were solidified using a geopolymer mixture GEOCEM (producer GEOFIX Ltd., Slovak Republic). The value of compressive strength linearly decreased with increasing addition of RAW from the value of 16.1 MPa to 12.4 MPa for radioactive expanded clay balls solidified and from the value of 16.1 MPa to 10.6 MPa in the case of radioactive sludge. Leaching test carried out according to ANSI/ANS 16.1.1986 showed that the calculated value of leachability index L i at the highest proportion (30 wt.%) of radioactive expanded clay balls or radioactive sludge reached the value L i = 10.3 or L i = 9.7, respectively.