HIPed Tailored Hollandite Waste Forms for the Immobilization of Radioactive Cs and Sr

Abstract

Hot isostatically pressed tailored hollandite waste forms were used to demonstrate the immobilization of Cs and Sr are separable from spent nuclear fuel, as well as Ba and Rb. Four hollandite formulations were investigated, two samples with ∼12 wt% waste loading (on an oxide basis) and two with ∼18 wt% waste loading. Two of the samples were Al‐substituted and the other two contained Mg. The hollandite in the Al‐substituted samples contained all the waste cations, as designed, but this was not the case in the Mg‐substituted samples. The hollandite in the Mg‐substituted samples did not contain all the waste cations, with ∼50% of the Sr forming SrTiO3 as a secondary phase. This resulted in waste forms that were not as durable, with respect to Cs, as their Al counterparts. The formation of SrTiO3 had little effect on the Sr release rates and was not detrimental to the Mg‐substituted hollandite waste form. For the Al‐substituted samples, the MCC‐1 normalized release rates were <0.06 g·(m2·day)−1 at 0–28 days for all elements, while the Cs release rates remained at 2.0 g·(m2·day)−1 at 0–28 days for the Mg‐substituted samples.

Quantum-Mechanical Methods for Quantifying Incorporation of Contaminants in Proximal Minerals

“…Overall, Tc single defects were shown to have lower energy than Ru ones, indicating that Tc would more readily enter the rutile structure. The extent of dopant incorporation and preferred cluster configuration was modeled over a range of temperatures and the computed results correlate well with experimental observations [38][39][40].…”

Dynamic immobilization of simulated radionuclide 133 Cs in soil by thermal treatment/vitrification with nanometallic Ca/CaO composites

“…It can be applied both in-situ and above ground in a treatment unit (ex-situ), using either borosilicates or aluminosilicates (Montagna et al, 2011;Park et al, 2011). The use of hollandite is frequently mentioned (Carter et al, 2009). Glass waste forms, as compared to grouted or cemented waste structures, are expected to be more stable over longer periods of time, due to the corrosion resistance of glass (Audero et al, 1995).…”

“…Among the methods of waste stabilization, vitrification is the most effective in the prevention of radioactive wastes leaching from soil, due to the effective immobilization of radioactive wastes atoms into the aluminosilicate matrix of the glassy product (Carter et al, 2009). Vitrification is a high temperature process in which organic matter is incinerated and mineral matter is melted and a slag is quickly cooled to obtain the product of vitrification in the glassy form.…”

Immobilization of Cs and Sr to HZr2(PO4)3 using an autoclave

“…Conventional methods of the immobilization of radioactive Cs and Sr are by forming a borosilicate glass or a ceramic such as supercalcine, SYNROC and titanium oxide Ti(OH) 4 [3][4][5][6][7][8][9][10][11][12]. A process based on borosilicate glass has been of practical use, but accompanied by drawbacks as follows.…”