B. Radiguet, A. Barbu, and P. Pareige, Understanding of copper precipitation under electron or ion irradiations in FeCu0.1 wt% ferritic alloy by combination of experiments and modelling, Journal of Nuclear Materials, vol.360, issue.2, pp.104-117, 2010.

J. Pakarinen, M. Khafizov, L. He, C. Wetteland, J. Gan et al., Microstructure changes and thermal conductivity reduction in UO 2 following 3.9 MeV He 2+ ion irradiation, Journal of Nuclear Materials, vol.454, issue.1-3, pp.283-289, 2014.

P. Garcia, G. Martin, P. Desgardin, G. Carlot, T. Sauvage et al., A study of helium mobility in polycrystalline uranium dioxide, J. Nucl. Mater, vol.430, pp.156-165, 2012.

A. Debelle, A. Boulle, F. Garrido, and L. Thomé, Strain and stress buildup in He-implanted UO 2 single crystals: an X-ray diffraction study, J. Mater. Sci, vol.46, pp.4683-4689, 2011.
URL : https://hal.archives-ouvertes.fr/in2p3-00596966

O. Ulrich, X. Biquard, P. Bleuet, O. Geaymond, P. Gergaud et al., A new white beam X-ray microdiffraction setup on the BM32 beamline at the European Synchrotron Radiation Facility, Rev. Sci. Instrum, vol.82, p.33908, 2011.

J. Chung and G. Ice, Automated indexing for texture and strain measurement with broad-bandpass x-ray microbeams, J. Appl. Phys, vol.86, p.5249, 1999.

A. Macdowell, R. Celestre, N. Tamura, R. Spolenak, B. Valek et al., Submicron X-ray diffraction, Nuclear Instruments and Methods in Physics Research A, pp.936-943, 2001.

F. Hofmann, D. Nguyen-manh, M. Gilbert, C. Beck, J. Eliason et al., Lattice swelling and modulus change in a helium-implanted tungsten alloy: Xray micro-diffraction, surface acoustic wave measurements, and multiscale modelling, Acta Materialia, vol.89, pp.352-363, 2015.

A. Richard, H. Palancher, E. Castelier, J. Micha, M. Gamaleri et al., Strains in light-ion-implanted polycrystals: influence of grain orientation, J. Appl. Cryst, vol.45, pp.826-833, 2012.

M. Ibrahim, E. Castelier, H. Palancher, M. Bornert, S. Caré et al., Laue pattern analysis for 2D strain mapping in light ion implanted polycrystals, Journal of Applied Crystallography, vol.48, pp.990-999, 2015.

T. Nguyen, A. Debelle, A. Boulle, F. Garrido, L. Thom et al., Mechanical response of UO 2 single crystals submitted to low-energy ion irradiation, J. Nucl. Mater, vol.467, pp.505-511, 2015.
URL : https://hal.archives-ouvertes.fr/hal-01224512

H. Palancher, P. Goudeau, A. Boulle, F. Rieutord, V. Favre-nicolin et al., Strain profiles in ion implanted ceramic polycrystals: An approach based on reciprocal-space crystal selection, Applied Physics Letters, vol.108, p.31903, 2016.
URL : https://hal.archives-ouvertes.fr/cea-01851584

H. Palancher, R. Kachnaoui, G. Martin, A. R. -c.-richaud, C. Onofri et al., Strain relaxation in He implanted UO 2 polycrystals under thermal treatment: An in situ XRD study, Journal of Nuclear Materials, vol.476, pp.63-76, 2016.
URL : https://hal.archives-ouvertes.fr/cea-01851583

J. Ziegler, J. Biersack, and M. Ziegler, SRIM the stopping and range of ions in matter, 1985.

M. Ibrahim, Etude du comportement mécanique dUO 2 implanté en hélium par micro-diffraction des rayons X et modélisation parélémentsparéléments finis, 2015.

I. Fritz, Elastic Properties of UO 2 at High Pressure, J. Appl. Phys, vol.47, p.4353, 1976.

V. Hein and F. Erdogan, Stress singularities in a two-material wedge, International Journal of Fracture Mechanics, vol.7, issue.3, pp.317-330, 1971.

D. Bogy, Two edge-bonded elastic wedges of different materials and wedge angles under surface tractions, Journal of Applied Mechanics, vol.38, issue.2, pp.377-386, 1971.

R. Zwiers, T. Ting, and R. Spilker, On the logarithmic singularity of freeedge stress in laminated composite under uniform extension, Journal of Applied Mechanics, vol.49, pp.561-569, 1982.

G. Martin, P. Garcia, C. Sabathier, G. Carlot, T. Sauvage et al., Helium release in uranium dioxide in relation to grain boundaries and free surfaces, Nucl. Instr. and Meth. B, vol.268, pp.2133-2137, 2010.

, Figure 1: Schematic representation of a polycrystalline sample implanted in a thin surface layer, coloured in red. The X-ray penetration depth is coloured in green. The X-ray incident beam is diffracted by the implanted layer and the strain free substrate

, Figure 2: Mapping of the displacement gradients normal component ? z,z measured by µ-XRD technique, vol.11

, Two UO 2 polycrystals are implanted with helium ions at 60 keV -10 16 ions/cm 2 (a) and 500 keV -10 16 ions/cm 2 (b)