A Review of 25 years of Corrosion Studies on HLW Container Materials at the CEA
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0985-NN08-05
A Review of 25 years of Corrosion Studies on HLW Container Materials at the CEA Max Helie Department of Physical Chemistry, French Atomic Energy Commission, DPC/SCCME, Bât 458, Centre d'Etudes de Saclay, Gif sur Yvette, 91191, France
ABSTRACT The Commissariat à l'Énergie Atomique (CEA, French Atomic Energy Commission) has been involved in researches on nuclear waste management for more than 25 years. One of the key issues is the prediction of the long term behavior and aging of the High Level Waste (HLW) containers in order to develop concepts that will ensure the confinement of the activity over extremely long periods of time. Preliminary studies were carried out on two concepts, one of a thin "corrosion resistant" container made of titanium or nickel base alloy, and the other on a thick "corrosion allowance" container made or carbon steel. The results of these experiments showed that the "corrosion resistant" concept led to a high uncertainty on the development and propagation rate of localized forms of corrosion, and the concept of geological disposal in an argillaceous host formation of thick waste containers made of carbon steel was chosen as the reference for further studies. This eventually led to the voting of a law relative to nuclear waste management on June 28th 2006, which endorses the geological disposal of corrosion allowance containers as the reference solution, while stating than an effort must be kept on the research on actinides transmutation to reduce the time during which a geological disposal facility has to be proven capable to ensure the confinement of the radioactive waste. Studies are still in progress to better assess the corrosion mechanisms relevant to this situation in order to provide reliable models for the long term prediction of the containers corrosion behavior. INTRODUCTION In the early 70s, after the events in the Middle East that are referred to as the "oil shock", France chose to adopt an energy policy largely based on nuclear power, and today roughly more than 75% of the electricity produced come from the 59 Pressurized Water nuclear Reactors (PWRs) operated by Électricité de France (EDF) with a total capacity of over 63 GWe. If nuclear power is quite well accepted as a necessity to achieve energy independence, the problem of dealing with the radioactive waste arose very early after the launching of the nuclear program. For this reason, the Commissariat à l'Énergie Atomique (CEA, French Atomic Energy Commission) has been involved in researches on nuclear waste management for more than 25 years. One of the key issues is the prediction of the long term behavior and aging of the High Level Waste (HLW) containers in order to develop concepts that will ensure the confinement of the activity over extremely long periods of time. The main threat to the containers integrity is their possible corrosion over time which depends on both the environmental conditions and the constitutive material of the containers. This paper summarizes the corrosion studies that have been carr
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