Background

Due to its low permeability properties and high radioactivity absorbing capacity, concrete is used for parts of radioactive waste storage facilities in both near-surface disposal of low and intermediate-level waste and in deep geological disposal of high-level waste. These structures are required to be safe, functional and reliable [1, 2], and in some cases reversible and retrievable, with minimum maintenance in varying environments (temperature, relative humidity, CO2, pressure, etc.) for several hundred years, a timespan significantly longer than a human lifetime.

Demonstrators representing containers for intermediate-level long-lived (IL-LL) waste [3]

During long-term exposure to underground conditions, with constant air flow during retrievable stage from the inside and water pressure from the outside, a change in the chemical environment around reinforcement due to carbonation is inevitable, consequently leading to failure of the stable chemical environment around steel reinforcement [3]. Premature degradation of these structures could have detrimental consequences on the environment and humans, such as release of radionuclides, radiolysis, uncontrolled underground degradation, and irretrievability.

Research objective

The overall aim of the project is to propose a phenomenological model to the whole propagation process of carbonation-induced corrosion of reinforced concrete structures used for radioactive waste disposal, which is coupling chemistry-transport and mechanical damage models, and is describing all interconnected and consequential phases of this specific corrosion process.

Gain of lacking information through PHENEMICS project

Expected results

After termination of the project the properties of inner and outer layer of corrosion products will be defined, with clear understanding of their long-term formation mechanism and mineralogical and micromechanical transformation. Next, the kinetics of the transport and path of corrosion products will be revealed. Finally, the influence of concrete chemistry and microstructure will be defined.

[1] EU Directive 2011/70/EURATOM community framework for the responsible and safe management of spent fuel and radioactive waste

[2] Nuclear Energy Agency Reversibility of Decisions and Retrievability of Radioactive Waste, OECD/NEA Publishing, 2012, http://www.oecd-nea.org/rwm/reports/2012/7085-reversibility.pdf

[3] http://www.andra.fr/download/andra-international-en/document/editions/310.pdf