The Use of Sulfur Chloride Systems in the Digestion and Purification of Zircaloy Nuclear Fuel Cladding
Date of Award
Master of Science
David Jenkins, Konstantinos Vogiatzis, Stephen Chmely
The overarching goal of this research has been to develop and understand a low-temperature protocol for the digestion of zirconium nuclear fuel cladding. The basic goal will be to reduce the used cladding to low-level radiological waste that can be disposed of more easily and at a reduced cost. A “blue sky” goal will be to eventually recycle the cladding to be reused in industrial processes. A hypothesis of this project is that by using various sulfur chloride compounds, the digestion of Zircaloy® can be converted to zirconium(IV) tetrachloride (ZrCl4) at low temperatures and the purification/decontamination can be accomplished through a crystallization using thionyl chloride or other sulfur chloride reagents. Three sulfur chloride reagents were investigated, thionyl chloride (SOCl2), sulfur dichloride (SCl2) and sulfur monochloride (S2Cl2). At 150 °C for each of these reactions the speed at which they digest the metal is very different. For SOCl2 (2.937 g Zr, 1.3 times of excess SOCl2), 30 – 40 hours; SCl2 (3.033 g Zr), 28 hours; and S2Cl2 (2.950 g Zr, 2.5 times excess of S2Cl2), 3 hours. Recrystallization of ZrCl4 was accomplished using SOCl2 and preliminary study of ZrCl4 in SOCl2 was conducted. A cloud point technique was used to determine the solubility. This was accomplished by dissolving ZrCl4 in SOCl2 then removing SOCl2 at a specific temperature until crystallization occurred. The solubility was high at high temperature and was very temperature dependent over the range of 0 °C to 50 °C, the solubility increased by a factor of almost 4. Understanding the solubility will aid in the development of a purification strategy due to high-temperature dependence.
Travis, Jordan, "The Use of Sulfur Chloride Systems in the Digestion and Purification of Zircaloy Nuclear Fuel Cladding. " Master's Thesis, University of Tennessee, 2019.