Research on the powderization treatment of uranium-zirconium solid solution simulated nuclear fuel debris using thermochemical redox reaction

Abstract

ABSTRACT In order to facilitate the dissolution of these insoluble nuclear debris from the Fukushima Daiichi NPS accident, it is necessary to investigate methods of pulverizing them to increase their surface area. For uranium and zirconium oxides in nuclear fuel debris, we proposed a pretreatment method using a redox method to achieve powdering. In this study, the simulated nuclear fuel debris pellets with uranium-zirconium ratio 9:1 and 1:1, and the pellet containing U, Zr, Fe, Gd, Nd and Si (65%:10%:10%:5%:5%:5%) were subjected to heating oxidation experiments in an oxygen atmosphere and reduction experiments after oxidation. The feasibility of pulverizing uranium-zirconium solid after heating and oxidation was demonstrated. And the product of the powder after redox reaction, uranium dioxide to triuranium octoxide was confirmed by XRD. Thus increasing the surface area required for dissolution or chemical conversion to soluble compounds can be expected.