Synthesis and spark plasma sintering of solid-state matrices based on calcium silicate for 60Co immobilization

Abstract

An effective sorption material for the immobilization of cobalt radionuclides into highly safe and reliable solid-state matrices is proposed. The resulting silicate sorbent СaSiO 3 had an amorphous mesoporous structure (A BET 53 m 2 /g) and a sorption capacity Co ions of 3.32 mmol/g. The physico-chemical characteristics of the СaCoSi 2 O 6 sample obtained after Co 2+ ions sorption were studied using XRD, N 2 and Ar adsorption-desorption, SEM-EDX and TG/DTA methods. Solid-state silicate matrices characterized by high density values (2.86–3.16 g/cm 3 ), compressive strength (150–637 MPa) and Vickers microhardness (1.80–5.25 GPa) were obtained by spark plasma sintering (SPS). The sample obtained at 1000 °C had the lowest values of Co 2+ ions leaching (R Co ~10 −7 g/(cm 2 ×day)) and diffusion coefficient (De 1.73 ×10 −17 cm 2 /s) from silicate matrices. Thus, the obtained СaCoSi 2 O 6 silicate matrices saturated with Co ions comply with the regulatory requirements of GOST R 50926–96 and ANSI/ANS 16.1 for 60 Co immobilization. • Amorphous CaSiO 3 with 3.32 mmol/g Co ions sorption capacity was prepared. • SPS method allowed to obtain the CaCoSi 2 O 6 matrices at 1000 °C for 2 min. • CaCoSi 2 O 6 solid-state matrices exclude Co 60 ions leaching and diffusion. • The characteristics of CaCoSi 2 O 6 matrices exceeded the GOST and ANSI/ANS 16.1 requirements.