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Waterside corrosion of Zircaloy cladding in pressurized water reactors (PWRs) is largely dependent upon the operating parameters and microstructure of the zirconium alloys. The impact of these parameters on the corrosion kinetics of Zircaloys is investigated on the basis of empirical data and experiences that can be interpreted using existing corrosion models. The influence of thermo-hydraulic data, heat flux, local boiling conditions, and of the growing oxide films has been studied from corrosion tests performed in static autoclaves or in out-of-pile loops. These parametric investigations are described as well as the models that were developed. The impact of microstructure is studied from the comparison of the corrosion behavior of different Zircaloy-4 specimens corroded in out-of-pile tests. In particular, a poor corrosion resistance of an experimental Zircaloy-4 material is analyzed as a function of the microstructure close to the metal/oxide interface. The impact of the alloy composition and primary coolant chemistry on the corrosion kinetics of Zircaloy-4 is modeled empirically or uses a mechanistic approach that proposes a series of chemical equations with a mathematical representation of the kinetics. These proposed models are then used to investigate the corrosion behavior of Zircaloy-4 cladding in 17 by 17 plants for rods irradiated at high burnups. Higher PWR operating cycles, core average coolant temperature, power, and elevated primary coolant lithium concentrations (3.5 to 4 ppm) are then simulated and discussed in terms of Zircaloy corrosion resistance considerations.

This study presents the lead alloy system chemistry analysis for use as nuclear coolant or spallation target in ADS related systems in order to set down the needs for purification processes and monitoring. The study is limited here to the two main impurities, oxygen and iron. The analysis of the various potential pollution sources that may occur during the various operating modes is given, as well as a first pollution rate assessment. In order to limit the consequences in term of contamination (clogging) and corrosion, it is necessary to define specifications for operation as regards oxygen and iron content in the fluid. As iron cannot be measured and controlled up to now, the best specification is to set the oxygen as high as possible, defined by the cold leg interface temperature to ensure tolerable contamination, in order to maximize the oxidation area to ensure corrosion protection by self-healing oxide layer for the entire system.

Abstract:The European FP7 project HycycleS focuses on providing detailed solutions for the design of specific key components for sulphur-based thermochemical cycles for hydrogen production. The key components necessary for the high temperature part of those processes, the thermal decomposition of H 2 SO 4 , are a compact heat exchanger for SO 3 decomposition for operation by solar and nuclear heat, a receiver-reactor for solar H 2 SO 4 decomposition, and membranes as product separator and as promoter of the SO 3 decomposition. Silicon carbide has been identified as the preferred construction material. Its stability is tested at high temperature and in a highly corrosive atmosphere. Another focus is catalyst materials for the reduction of SO 3 . Requirement specifications were set up as basis for design and sizing of the intended prototypes. Rigs for corrosion tests, catalyst tests and selectivity of separation membranes have been designed, built and completed. Prototypes of the mentioned components have been designed and tested.Keywords: sulphur; catalyst; silicon carbide; membranes; thermochemical cycle.Reference to this paper should be made as follows: Roeb, M., Thomey, D., Graf, D., Sattler, C., Poitou, S., Pra, F., Tochon, P., Mansilla, C., Robin, J-C., Le Naour, F., Allen, R.W.K., Elder, R., Atkin, I., Karagiannakis, G., Agrafiotis, C., Konstandopoulos, A.G., Musella, M., Haehner, P., Giaconia, A., Sau, S., Tarquini, P., Haussener, S., Steinfeld, A., Martinez, S., Canadas, I., Orden, A., Ferrato, M., Hinkley, J., Lahoda, E. and Wong, B. (2011) 'HycycleS: a project on nuclear and solar hydrogen production by sulphur-based thermochemical cycles ', Int. J. Nuclear Hydrogen Production and Applications, Vol. 2, No. 3, Sabine Poitou studied Chemical Engineering at ENSIC (Ecole Nationale Supérieure des Industries Chimiques) in the National Polytechnic Institute of Lorraine (1991Lorraine ( -1994. Working at the CEA since 1998 as Research Engineer, she was involved on nuclear waste treatment and conditioning studies until 2007. Since 2008, her activity has concentrated on industrial development of hydrogen production with nuclear reactor coupled processes. George Karagiannakis received his PhD in Chem. Eng., at the Aristotle Univ. of Thessaloniki, Greece. He has been an Affiliated Researcher at APTL since 2006 and a member of the Nanoparticles and Catalysts Group. He has expertise in catalytic and electrocatalytic studies, with emphasis in those involving hydrogen productions. He has participated in several national and EU research projects.Christos Agrafiotis is a Principal Researcher at CPERI, Chemical Engineer. He received his PhD in Chem. Eng., from SUNY, Buffalο, USΑ. He has more than 15 years of expertise in powder synthesis and catalytic coating of monolithic reactors, participated in several EU-and nationally-funded research projects in these areas, and he is the author of more than 40 relevant publications in international journals and proceedings. Athanasios Konstandopoulos is the Director of APTL and C...