Leaching Behavior of Salt Wastes Conditioned with Sodalite Blended with Two Different Glass Powders

Abstract

Two different glass powders (a commercially available glass frit and a borosilicate glass) have been used as blending agents for sodalite, an aluminosilicate mineral able to condition chloride salt wastes from pyrometallurgical processes. The synthesis of the mineral phase has been made through a process recently proposed by Idaho National Laboratory in USA, starting from a homogeneous powder of nepheline, chloride salts and glass. The mix, put into an alumina crucible, was introduced in a furnace inside an argon-atmosphere glove-box. The furnace temperature was then raised to 925 C, where it was kept for 7 hours. Leach tests under static conditions, according to ASTM C1285-02, have then been carried out on the final waste forms at room temperature (23 C) and in an oven at 90 C. SEM investigations have also been made before and after leach tests, in order to check the status of the powders. In particular the effect of the leaching process on the surface of the sodalite grains at 90 C from 30 to 150 days has been evidenced. The results obtained in the present study have been usefully compared to those from a similar test on a sodalite added with a glass frit by Idaho National Laboratory. Financial support from the Nuclear Fission Safety Program of the European Union is gratefully acknowledged (project ACSEPT, contract FP7-CP-2007-211 267).

An experimental study on Sodalite and SAP matrices for immobilization of spent chloride salt waste

“…An attempt was made to collect as much as possible literature data comparable with the results of the present study. For this purpose, Table 3 reports herein obtained data and literature results related to: analogous ceramic wasteforms previously studied by the present authors [24,25,30]; ceramic waste forms containing sodalite with the addition of 25 wt% glass frit, synthesized at Argonne National Laboratory…”

Molten salt reactors and electrochemical reprocessing: synthesis and chemical durability of potential waste forms for metal and salt waste streams

“…Results from PCT-B experiments performed by Giacobbo and collaborators on SAP-derived waste forms are shown in Figure 9 [132,133]. Solution feedback appears to attenuate the release of Si-containing species while higher alkali release rates exhibit sub-linear (root-time) behaviour indicative of diffusive release.…”

Solubility constants of hydroxyl sodalite at elevated temperatures evaluated from hydrothermal experiments: Applications to nuclear waste isolation

“…For example, radioactive iodine ( 129 I) which has a half-life of 15.7 million years can potentially be immobilized in a sodalite waste form. Also, for contaminated electrolytes produced when electrorefining spent nuclear fuel (e.g., Sheppard et al, 2006;Hirabayashi et al, 2012;Lepry et al, 2013;Capone et al, 2014;Maddrell et al, 2014;Gilbert, 2013Gilbert, , 2015, sodalite is a candidate waste form. The reprocessing of spent nuclear fuel for disposition using an electrometallurgical method results in a high-level waste salt with chloride (Priebe andBateman, 2006, 2008).…”