No abstract

No abstract

Irradiation is one of the characteristic conditions that nuclear wasteforms must withstand to assure integrity during their service life. This study investigates gamma irradiation resistance of an early age slag cement-based grout, which is of interest for the nuclear industry as it is internationally used for encapsulation of low and intermediate level radioactive wastes. The slag cement-based grout withstands a gamma irradiation dose of 4.77 MGy over 256 hours without reduction in its compressive strength; however, some cracking of irradiated samples was identified. The high strength retention is associated with the fact that the main hydration product forming in this binder, a calcium aluminum silicate hydrate (C-A-S-H) type gel, remains unmodified upon irradiation. Comparison with a heat-treated sample was carried out to identify potential effects of the temperature rise during irradiation exposure. The results suggested that formation of cracks is a combined effect of radiolysis and heating upon irradiation exposure.

No abstract

The present study investigated the feasibility of the immobilisation of sulphate bearing radioactive wastes in blast furnace slag (BFS) based binders. BaSO 4 -BFS composites were produced via two methods using Na 2 SO 4 as a waste simulant, along with Ba(OH) 2 to promote precipitation of BaSO 4 in an insoluble sulphate form and the consequent activation of the BFS. BaSO 4 was effectively formed by both methods, and solid wasteforms were successfully produced. Although both methods produced BaSO 4 embedded in the cement-like composites, different reaction products including ettringite and witherite were produced, depending on the order Ba(OH) 2 was mixed with the system. These results show that the immobilisation of soluble sulphate-bearing aqueous wastes is achievable in Na 2 SO 4 -Ba(OH) 2 -BFS composites.