Shelfife of half-life radioactive waste containers from the point of view of the corrosion of the steel frames

A comparative study is presented of the behavior of heavily used concrete made with three kinds of cement (normal Portland - CPN -, highly sulfate resistant - ARS - and high furnace slag - EAH -) when the steel used as reinforcement is corroding. The results are used to evaluate the durability of containers for half-life radioactive waste (CRMA). The study combines non-destructive electrochemical tests using concrete test pieces containing steel bars, with measurements done on a prototype of a life size container equipped with instruments for this purpose. The incidence of chloride ions, sulfates and carbonation of the concrete in the corrosion process of the frame was evaluated. The electrochemical parameters that define the corrosion process of the steel in the concrete (corrosion potential, polarization resistance and electrical resistivity of the concrete) were determined regularly during a 1600 day period. The coefficients of diffusion of chloride and carbon dioxide ions in the concrete were also determined, obtaining values that are comparable to those for high quality concretes. The results obtained to date reveal that the concretes studied provide the steel with a passive state when corrosion occurs in the three conditions of exposure that were tested. A growing trend over time is seen for the values of electrical resistivity even for the immersed test pieces, which shows that the seasoning process for the concrete in the study continues (au)