Quantification of irradiation-induced defects in UO2 using Raman and positron annihilation spectroscopies

Abstract

Quantification of irradiation-induced defects IN UO 2 using Raman and positron annihilation spectroscopies, Acta Materialia (2018), doi: https:// AbstractIn UO 2 , Raman spectroscopy has recently put into evidence the existence of a specific signature, referred to as the triplet defect bands, which is characteristic to irradiation damages. In this work, we perform a detailed experimental analysis to investigate how this Raman signature can be used to characterize irradiated nuclear fuels. For this purpose, an electron irradiation experiment of sintered UO 2 disks coupled with ex situ Raman and positron annihilation spectroscopy measurements were carried out. The obtained findings showed that the Raman defect bands take their origin from the ballistic collisions of the incident electrons with the U and O atoms and are due to the formation of point defects. These defects induce the re-arrangement of UO 2 lattice atoms and give rise to domains with symmetry lower than Fm-3m with the loss of one or more symmetry elements, such as translational symmetry, centering F, mirror or rotational symmetry operations.

Phase and defect evolution in uranium-nitrogen-oxygen system under irradiation

“…Energetic particles can knock atoms out of their lattice site and create point defects (vacancies, interstitials). These point defects can evolve into extended defects such as dislocation loops, cavities, or stacking fault tetrahedra [11][12][13][14][15]. In some cases, element segregation, phase transition and chemical interactions can be induced by irradiation [16][17][18][19][20].…”

Thermal Energy Transport in Oxide Nuclear Fuel

“…Optical, photoluminescence, and Raman spectroscopies can successfully detect oxygen vacancies while PAS directly measures cation vacancies and the defect complexes of vacancies and impurities. Combining more than one technique such as PAS and Raman spectroscopy can thus be effective in revealing the variety of different types of defects present in actinide oxides [378]. For example, applying PAS and optical spectroscopies can solve the challenge in assigning absorption/luminescence peaks to a specific type of defect.…”

“…Combining more than one technique such as PAS and Raman spectroscopy can thus be effective in revealing the variety of different types of defects present in actinide oxides. 378 3.1.2. Intrinsic Point Defects: Characterization and Modeling.…”

In Situ Raman Spectroscopy Monitoring of Material Changes During Proton Irradiation

“…5 The sensitivity of Raman spectroscopy to crystallinity, defects, and internal stresses makes it a method of predilection to carry out these investigations. [6][7][8] Nevertheless, long working distance devices are required, in order to make measurements through the irradiation chamber window, and the system must be portable to fit into the irradiation facility. Since the beginning of the 2000s, long working distance systems based on high resolution commercial devices are coupled with other instruments.…”