Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets

L Biasetto,A Andrighetto,O Dieste Blanco,R Eloirdi,D Staicu,P Amador-Celdran,S Corradetti,S Carturan

doi:10.1038/s41598-018-26572-5

Abstract

The development of tailored targets for the production of radioactive isotopes represents an active field in nuclear research. Radioactive beams find applications in nuclear medicine, in astrophysics, matter physics and materials science. In this work, we study the use of graphene both as carbon source for UO2 carbothermal reduction to produce UCx targets, and also as functional properties booster. At fixed composition, the UCx target grain size, porosity and thermal conductivity represent the three main points that affect the target production efficiency. UCx was synthesized using both graphite and graphene as the source of carbon and the target properties in terms of composition, grain size, porosity, thermal diffusivity and thermal conductivity were studied. The main output of this work is related to the remarkable enhancement achieved in thermal conductivity, which can profitably improve thermal dissipation during operational stages of UCx targets.

Highlights

Actinide carbides are potential candidates both as materials for improving the safety of generation IV fast nuclear reactors[1,2], and as target for the production of second generation Isotope Separation On Line facilities (ISOL)[3]
Using a molybdenum grid as a crucible, it was observed that the parts directly in contact with the metal showed a higher reactivity than expected, independently on the type of carbon source used for the carbothermal reaction
From the chemico-physical and functional characterization reported above, it is clear that graphene derived uranium carbides have higher thermal conductivity than those derived from graphite

Summary

Introduction

Actinide carbides are potential candidates both as materials for improving the safety of generation IV fast nuclear reactors[1,2], and as target for the production of second generation Isotope Separation On Line facilities (ISOL)[3]. In both cases the material must withstand high temperatures (up to 2273 K) and eventually heat-induced stresses. Actinide carbides differ from transition metal carbides, due to unfilled 5 f orbital in their electronic structure For instance this leads to strong chemisorption of UC2 in graphene[13] with concomitant consequences in terms of their mechanical and thermal properties. Other refractory carbides considered for ISOL facilities include TiC [11] produced as nanostructured target in order to enhance its release efficiency, and lanthanum carbide[15] for which a slip casting process was developed to obtain refractory carbide-carbon composites

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Conclusion