The Use of Alkali Activated Materials in Nuclear Industry

Alkali Activated Materials (AAMs) are interesting alternative binder materials to Ordinary Portland Cement (OPC) for application in nuclear safety structures and radioactive waste management. AAMs are highly chemical and temperature resistant and can reach a high shielding capacity for gamma irradiation. AAMs also have a low calcium content which enables the addition of fluorine to reduce the H2 production for Mg-containing wastes and limits the formation of 41Ca due to neutron activation. In general, AAMs have lower radiolytic hydrogen yields compared to OPC. Fayalite slag based AAMs were proven to have a similar gamma shielding capacity to basalt-magnetite concretes. Boron based AAMs form an interesting opportunity for neutron shielding. Since dehydration in AAMs is limited, better neutron shielding capacities for AAMs can be obtained compared to aged concrete. The absence of portlandite, the low water content and the high alkalinity, make AAMs interesting candidates for the conditioning of certain radioactive waste streams. Ions as Cs+ and Sr2+ can be incorporated in the AAM-gel or can be trapped in the self-generated or introduced zeolite structures in the AAM. Also precipitation of several elements as a hydroxide can promoted by selecting the right raw material and activation solution.