A STUDY ON OXIDATION TREATMENT OF URANIUM METAL CHIP UNDER CONTROLLING ATMOSPHERE FOR SAFE STORAGE

• DOI: 10.5516/net.2011.43.4.391
• Publication Date: 2011-11-09T09:20:54Z
• Authors: Chang-Kyu Kim; Chul-Goo Ji; Sang-Oh Bae; Yoon-Myeoung Woo; Jong-Goo Kim; Yeong-Keong Ha
• Keywords: Autoignition temperature; Oxidizing agent; Oxidation process

The U metal chips generated in developing nuclear fuel and a gamma radioisotope shield have been stored under immersion of water in KAERI. When the water of the storing vessels vaporizes or drains due to unexpected leaking, the U metal chips are able to open to air. A new oxidation treatment process was raised for a long time safe storage with concepts of drying under vacuum, evaporating the containing water and organic material with elevating temperature, and oxidizing the uranium metal chips at an appropriate high temperature under conditions of controlling the feeding rate of oxygen gas. In order to optimize the oxidation process the uranium metal chips were completely dried at higher temperature than 300℃ and tested for oxidation at various temperatures, which are 300 ℃, 400 ℃, and 500 ℃. When the oxidation temperature was 400℃, the oxidized sample for 7 hours showed a temperature rise of 60 ℃ in the self-ignition test. But the oxidized sample for 14hours revealed a slight temperature rise of 7℃ representing a stable behavior in the self-ignition test. When the temperature was 500 ℃, the shorter oxidation for 7 hours appeared to be enough because the self-ignition test represented no temperature rise. By using several chemical analyses such as carbon content determination, X-ray deflection (XRD), Infrared spectra (IR) and Thermal gravimetric analysis (TGA) on the oxidation treated samples, the results of self-ignition test of new oxidation treatment process for U metal chip were interpreted and supported.