RRFM 2009 Transactions - European Nuclear Society

Heavy ion irradiation of UMo7/Al fuel: methodological approach
E. Welcomme, H. Palancher, C. Sabathier, Ph. Martin, J. Allenou, C. Valot, F.
Charollais, M.C. Anselmet
CEA/Cadarache, DEN/DEC, 13108 Saint Paul Lez Durance - France
R. Jungwirth, W. Petry
FRM II Technische Universität München, Lichtenbergstr. 1, 85747 Garching - Germany
L. Beck
Maier Leibnitz Laboratorium, LMU/TUM, Am Coulombwall 6. 85748 Garching - Germany
C. Jarousse
AREVA-CERCA ♦ , Les Berauds, B.P. 1114, 26104 Romans Cedex - France
R. Tucoulou
ESRF, 6 rue Jules Horowitz, 38042 Grenoble - France
P. Lemoine
CEA/Saclay, DEN/DSOE, 91191 Gif sur Yvette - France
ABSTRACT
Heavy ion irradiation with an 80 MeV 127 I beam is used as out-of-pile technique in order to simulate the
in-pile growth of the UMo/Al interaction layer. However, irradiation conditions used in 2005-2006 do
not fully allow reproducing the characteristics of the in-pile interaction layer (IL). In this paper, a study
focussing on the influence of the different irradiation parameters on the thickness, nature and
composition of the interaction layer, is presented. The results are in excellent agreement with SRIM
calculations. The interest for heavy ion irradiation is supported by the evidence for a phase transition
γ-UMo(a) + α-U γ-UMo(b) as observed in pile (in this reaction, γ-UMo(a) has a higher Mo content
than γ-UMo (b)).
1. Introduction
During in-pile irradiation, U-Mo high density nuclear fuel is impacted by the formation
of a large interaction layer (IL) at the periphery of the U-Mo particles, embedded in the Al
matrix. This problem reduces the irradiation performance of the fuel element due to the
development of large porosities leading to pillowing and sometimes to breakaway swelling.
Thus to allow further use of UMo particular fuel, technological solutions to stabilize and
minimize the IL have to be found. Furthermore, this objective must be supported by an effort
to improve our understanding of the ILs nature and its kinetic of formation.
To simulate the in-pile growth of an IL in an UMo7/Al fuel, out-of-pile techniques have been
envisaged. Among them heavy ion irradiations using a typical fission fragment (Iodine energy
of 80 MeV) have demonstrated their efficiency to study the irradiation enhanced diffusion in
UMo/Al fuel [1, 2, 3 and 4]. However many experimental aspects regarding this technique
have to be analysed in detail in order to rigorously interpret the results and to make this tool
more robust and more representative of the in-pile irradiation phenomena. The main
objective is the routine use of ion irradiation to discriminate technological solutions envisaged
for limiting the growth of the UMo/Al IL.
♦ AREVA-CERCA, a subsidiary of AREVA NP, an AREVA and SIEMENS company
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