Chloride Diffusion into Nuclear Reactor Containment Buildings (RCBs) Situated in Hot Climate Environments

  • Mohamed AlAbdouli

Student thesis: Master's Thesis

Abstract

Elevated ambient temperatures are recognized to accelerate the chloride ion diffusion process in concrete towards the direction of the concentration gradient. Moreover, based on Soret's thermodiffusion principles, the diffusion process is said to be more severe in case a parallel same direction temperature gradient exists. The same is expected to be confronted in Pressurized Water Reactor (PWR) Containment Buildings (RCBs) that are to be situated in middle eastern coastal regions, which are prone to high concentrations of chlorides coupled with elevated climate temperatures. In line with this, it was attempted to experimentally reproduce the thermodiffusion principle to evaluate any apparent impact on the chloride diffusion process in concrete. Additionally, preliminary literature reported models to describe chloride diffusion under temperature gradient effect are tested and upgraded to yield chloride profiles for extended exposure period and under the additional influence of moisture gradient. Overall, findings showed that chloride profiles were higher when temperature gradient conditions existed. The same persisted with extended exposure period provided that the temperature profile was maintained. The factor of moisture gradient has also been shown to affect the chloride diffusion process; in fact, when tested separately, the magnitude of the effect was greater compared to the temperature gradient condition. Proposed modeling approaches were adequately representative of experimental findings and analytical findings revealed that chloride profiles estimated by proposed models would prevent long-term inaccuracies ranging from 30 to 100%, which resulted from the use of basic models based on Fick's law of diffusion. The current work is highly valuable as it ultimately leads to enhanced understanding and more thorough prediction of chloride diffusion and associated corrosion initiation in reinforced concrete, which are one of the dictating factors in service life studies of critical structures, such as RCBs.
Date of AwardApr 2022
Original languageAmerican English

Keywords

  • Corrosion
  • chloride diffusion
  • thermodiffusion
  • temperature gradient
  • nuclear reactor containment building
  • concrete aging.

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