Post-irradiation studies on LWR-MOX fuel fabricated by the optimized co-milling process

• Published in: Journal of nuclear materials Vol. 324; no. 2; pp. 198 - 202
• Main Author: Kleykamp, H
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.01.2004; Elsevier
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Installations for energy generation and conversion: thermal and electrical energy; P0700; U0200; F0700; N0100; R0200; Scanning electron microscopy; Oxide layer; X ray; Burnup; Cross section (collision); Fuel pin; Light water reactor; Nuclear reactor; Zircaloy; Concentration effect; Mixed fuel; Oxidation; Uranium dioxide
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2003.10.004

A LWR-MOX fuel pin cross-section irradiated up to 4.4% local burnup was examined by scanning electron microscopy and X-ray microanalysis. The fuel had been fabricated by the optimized co-milling process (OCOM) of UO 2 and PuO 2 powders of the final composition of U 0.7Pu 0.3O 2 and blending with UO 2 powder down to a typical LWR composition of U 0.949Pu 0.052O 2. The duplex structure of the highly burnt Pu rich agglomerates in the U rich fuel matrix remained. In the UO 2 matrix, 5.3% PuO 2 were observed at the fuel surface caused by the so-called rim effect. The cross-section averaged EOL PuO 2 concentration in the total fuel was 2.9% PuO 2. About 9% PuO 2 were measured in the dense areas of the high-porous agglomerates. Here, the burnup was calculated from the Nd concentration to be 19%. The cross-section averaged EOL Xe concentration in the total fuel was 0.29% Xe, resulting in a Xe release of 43% of the generated Xe. The oxidation of the inner Zircaloy-4 region attained a thickness up to 20 μm in direct contact with the Pu-rich agglomerates. The outer oxide layer had a thickness of 22 μm.