Abstracts and Available Papers Presented at the
2005 International RERTR Meeting

PHASE STABILITY AND DIFFUSION CHARACTERISTICS OF U-MO-X (X=SI, AL, ZR) ALLOYS

J.M.Park, H.J.Ryu, G.G.Lee, H.S.Kim, Y.S.Lee, C.K.Kim
Korea Atomic Energy Research Institute
150 Dukjin-dong, Yuseong-gu, Daejeon 305-353, Korea

and

Y.S.Kim, G.L. Hofman
Nuclear Engineering Division
Argonne National Laboratory, 9700 S. Cass Ave. Argonne, IL 60439, USA

ABSTRACT

As a means to reduce the reaction between the U-Mo and Al in U-Mo/Al dispersion fuels, a third element addition to U-Mo was proposed recently by Argonne National Laboratory. As preliminary tests before an in-reactor irradiation, we investigated by laboratory tests the efficacy of an addition of an X (= Si, Al, or Zr) element to U-7Mo in light of the gamma phase stability and diffusion reaction behavior. By using a vacuum induction melting technique, a third element was added to the U-7Mo. Gamma phase stability of the quenched specimens was tested by high temperature annealing tests. X-ray diffraction showed that the addition of a small amount (~0.2 wt%) of Si improved the gamma stability of the U-7Mo significantly whereas Al worsened it. Other elements revealed no effects. To examine the diffusion behavior, diffusion couples were made by encapsulating U-7Mo-X plates with pure Al plates and hydraulically pressing the layers. After an annealing at 550°C, the reaction layer thicknesses were measured. Annealings of 4.5 gU/cm³ U-7Mo-X/Al and U-7Mo/Al- Si dispersion fuels at 550°C and 580°C were carried out for 2 - 50 hrs to measure the growth rate. Reaction layer compositions of each diffusion couple were also measured by an electron probe microanalysis. The diffusion behavior of the U-7Mo was compared to that of U-7Mo-X alloys.

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