RRFM 2014: French research team wins Poster Prize

The annual RRFM (Research Reactor Fuel Management) conference took place this year in Ljubljana, the capital city of Slovenia, from 30 March to 3 April 2014. This flagship ENS technical conference brought together around 200 specialists in the field of nuclear research reactors to discuss a range of topics, including the fuel cycle of research reactors; safety and security priorities; the utilisation, operation and management of the reactors, new research reactor projects and the latest innovations related to reactor physics and thermo-hydraulics.

The wide-ranging RRFM 2014 programme featured many presentations given by experts in their respective fields, numerous highly focused debates, networking opportunities and a number of technical visits offered to delegates. In addition, as always, the conference provided a rich source of excellent technical papers, with over 120 published. There are too many of them to mention here, but ENS NEWS readers can consult them via the following link: www.rrfm2014.org

However, I would like mention one paper in particular, the one that was awarded the RRFM 2014 Poster Prize. It was a paper written by threee researchers from France and was entitled: Insights on the kinetics and mechanism behaviours of layer formation in UAl2-Al diffusion couple.

And here it is…….

(Editor-in-Chief)

INSIGHTS ON THE KINETICS AND MECHANISM BEHAVIORS OF LAYER FORMATION IN UAl2-Al DIFFUSION COUPLE

C. MOUSSA, O. TOUGAIT.
Institut des Sciences Chimiques de Rennes, UMR-CNRS 6226, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex -France

B. STEPNIK
AREVA-CERCA, 10 Rue Juliette Récamier, 69006 Lyon-France

ABSTRACT

UAl_x irradiation targets are produced by the thermal reaction between UAl₂ and Al powders. With this respect, the understanding of diffusion mechanism in the UAl₂/Al system is of interest. The present study aims to experimentally evaluate some fundamental features of the growing of the interaction product between UAl₂ and Al by means of diffusion couples experiments. The diffusion couples were prepared using as-cast UAl₂ and pure aluminum in the form of a tri-layer sandwich that was cold worked at 190(10)MPa in a die. The UAl₂-Al interfaces were investigated by SEM-EDS analysis, after heating the couples in a temperature range 575-645°C for dwell periods up to 70 hours. The growth rate of the interaction layer, that is function of time and temperature, is also influenced by the applied pressure. The major interaction phase, UAl₃, forms in the diffusion zone with planar morphology whereas for longer annealing times and at higher temperatures UAl₄ forms preferentially at the vicinity of both the open pores and cracks of the sample. In terms of mechanism, it can be proposed that the interdiffusion reactions occur in two separate steps (i) formation of UAl₃ from the reaction between UAl₂ and Al, (ii) formation of UAl₄ from the reaction between UAl₃ and Al. The formation of UAl₃ as the first phase was tentatively described according to the normal parabolic behavior of the layer thickening. However, the large dispersion of the data points hindered to evaluate a reliable value of the activation energy.