NuFuel & MMSNF 2015

First Workshop on Research into Nuclear Fuel in Europe
and Materials Modeling and Simulation for Nuclear Fuels Workshop
Karlsruhe, Germany, November 16th to 18th, 2015

Updated: Tue 08 Dec 2015, 14:27

Poster 5.2: Positron annihilation spectroscopy study in UO2: coupled theoretical and experimental approach

J. Wiktor1, G. Jomard1, M.F. Barthe2, M. Torrent3, Marjorie Bertolus1
  • 1: CEA, DEN, DEC/SESC, Centre de Cadarache, F–13108 Saint Paul Lez Durance Cedex, France
  • 2: CNRS/CEMHTI, CNRS UPR 3079/CEMHTI, F–45071 Orléans, France
  • 3: CEA, DIF, F–9129, Arpajon, France

Abstract

One of the experimental methods that can be used to study open volume defects is positron annihilation spectroscopy (PAS). This non-destructive technique consists in recording the radiation emitted at the beginning and the end of life of positrons in a material and deducing the properties of the positrons and the electrons with which they have annihilated. There are two positron annihilation characteristics that allow one to detect defects in materials: The first one is the lifetime of positrons in the material is mostly sensitive to the open volume of the defects. Second, the Doppler broadening of the annihilation radiation gives information on the chemical environment in which positron annihilate. These two characteristics can be measured experimentally. To identify the types of defects present in studied materials, however, comparison with other characterization methods or calculations is necessary.

Positron lifetime and Doppler broadening can be calculated using the two-component density functional theory. We performed self-consistent calculations of positron characteristics for vacancies and vacancy clusters in uranium dioxide using the implementation of the two-component density functional theory in the ABINIT code. The comparison of theoretical results with experimental measurements obtained for irradiated uranium dioxide will be presented along with the proposed identification of the observed signals.