In situ Raman scattering studies allow following real-time evolutions of volume or surface structures under extreme conditions. In nuclear materials sciences, ion irradiation-induced atomic organization modification and water radiolysis are of a major interest. In order to better understand these phenomena, we have developed an in situ versatile portable Raman spectroscopy system coupled with a cyclotron accelerator, allowing monitoring of a solid/liquid interface under irradiation and thus giving access to effects of radiolysis. The different parts of the system and their improvements are described in details. The system efficiency is highlighted by a comparative study of the time dependence of UO2 surface modification induced, on one hand by contact with water under irradiation by 5?MeV He2+ particles, and on the other hand by pure chemical alteration, through contact with a hydrogen peroxide solution. Copyright (c) 2012 John Wiley & Sons, Ltd.

Few data are available in the literature on the role of the water radiolysis on the corrosion of stainless steel core components in PWR operating conditions (300 degrees C, 155 bar). The present approach uses a high energy proton beam to control the production of radiolytic species at the interface between a stainless steel sample and water in a high temperature and high pressure (HP-HT) electrochemical cell working in the range 25 degrees C/1 bar-300 degrees C/90 bar. The cell is designed to record the free corrosion potential of the AISI 316L/water interface mounted in line with a cyclotron delivering the proton beam. The evolution of the potential is compared before, during and after the proton irradiation.The first results are obtained with an aqueous solution containing boron, lithium and dissolved hydrogen, as in PWR primary coolant circuit. The stainless steel/water interfaces are irradiated between 25 degrees C and 300 degrees C with protons emerging at 22 MeV at the interface. The flux is varied by five orders of magnitude, from 6.6 x 10(11) to 6.6 x 10(15) H+ m(-2) s(-1). The evolution of the free corrosion potential is highly dependent on the temperature and/or pressure. For a given temperature and pressure, it evolves with the flux and the ageing of the AISI 316L/water interfaces. An important role of the temperature of irradiation on the electrochemical response was observed. These results give a better understanding of the role of radiolysis on stainless steel corrosion in high temperature conditions. (C) 2011 Elsevier B.V. All rights reserved.

The materials used in electrical contact applications are constituted of a copper alloy (brass or bronze) electroplated with two coatings, a nickel layer (diffusion barrier) and a gold layer (corrosion barrier). There are some pores in the nickel and gold layers leading to corrosion of the underlying layers.To modify the gold coating microstructure, a laser surface treatment has been undertaken. An excimer laser is used firstly because the photon absorption coefficient is larger in UV range and secondly because the laser beam homogeneity is available for a surface treatment. The purpose of this surface treatment is to suppress the porosity of the gold layer, which is responsible of the corrosion pits, and to smooth the surface as the roughness prevents a correct electrical contact.The effects of the laser treatment are studied according to different surface parameters (roughness of the substrate, thickness of the two successive coatings, a nickel layer and a gold layer). A numerical code is used to simulate the influence of the laser beam parameter on the surface melting. Tests of corrosion are carried out in the humid synthetic air containing low contents of pollutants (NO2, SO2 and Cl-2). The techniques used to control these effects are optical microscopy and scanning electron microscopy (SEM). (C) 2002 Elsevier Science B.V. All rights reserved.