Getters for improved technetium containment in cementitious waste forms.

•KMS-2 and Sn(II) apatite were used as Tc getters in cementitious waste forms.•KMS-2 had higher capability of Tc removal from simulated low-activity waste.•Addition of KMS-2 (<0.08wt% of overall waste form)improved Tc retention.•Tc identified to remain associated with getter within the cured Cast Stone waste form.•Improved retention by KMS-2 linked to generation of Tc(IV)-sulfide species.