Evolution of corrosion parameters in a buried pilot nuclear waste container in el Cabril
- PDF / 1,052,750 Bytes
- 10 Pages / 432 x 648 pts Page_size
- 64 Downloads / 188 Views
Evolution of corrosion parameters in a buried pilot nuclear waste container in el Cabril Carmen Andrade1, Samuel Briz1, Javier Sanchez1, Pablo Zuloaga2, Mariano Navarro2 and Manuel Ordoñez2 1 Institute of Construction Science “Eduardo Torroja” (IETcc), CSIC, Serrano Galvache 4, 28033, Madrid, Spain. 2 ENRESA (Spanish Agency for Management of Radioactive Wastes) Emilio Vargas, 7, 28043, Madrid, Spain. ABSTRACT Modern concrete has a record of good performance of around 120 years although there are structures in perfect conservation made with roman concrete (mixture of lime and natural pozzolans). El Cabril repository has a design life of 300-500 years and therefore, it should keep its integrity much longer than the back experience we have on reinforced concrete structures, which makes necessary a closer monitoring with time on the aging of concrete in real conditions. With this purpose, Enresa has designed in collaboration with IETcc and Geocisa the installation of permanent sensors in a pilot nuclear waste container in buried conditions. The sensors were installed in 1995 for monitoring corrosion parameters and have been working until present. The non-destructive tests (NDT) applied are based in electrochemical measurements (corrosion rate, corrosion potential, electrical resistivity, concrete strains, oxygen availability). Relations between the climatic influence, the buried depth and the corrosion parameters are also presented. The results indicate that temperature is a very relevant variable influencing the measurements. All the other parameters evolve according to seasonal changes. Values of activation energies of the resistivity changes are given although it seems more adequate to model the evolution with time by simply plotting the values registered at 20 ± 2 ºC. INTRODUCTION El Cabril repository has a design life of 300-500 years with three main periods: i) operational, during the construction, ii) surveillance, where a minimum of monitoring is considered, and iii) the post-surveillance, where no more control is expected. The main cement based structures used as engineering barriers in the repository of El Cabril for low and medium radioactive wastes are the cells, the containers and the mortar filling the gaps between the drums introduced in the containers. Cells and containers are made of the same concrete composition while the mortar was specifically designed to be pumpable and with high impermeability (between 10-17 and 10-18 m2). The possible aggressions that the cement based materials can suffer during these periods have been identified to be: carbonation (during the operation only), water permeation (leaching) and reinforcement corrosion. More unlikely might be the bio-attack. Chlorides are not in the environment but they are inside the drums as part of analytical wastes. The description of the installations has already been reported before [1]. The design life of 300-500 years is longer than the existing experience on this kind of structures because the oldest structures in reinforced concrete were bui
Data Loading...
