Investigation of the properties of a bentonite sealing barrier affected by a gas breakthrough event

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F22%3A00370127" target="_blank" >RIV/68407700:21110/22:00370127 - isvavai.cz</a>

Result on the web

<a href="https://www.clayconferencenancy2020.com/" target="_blank" >https://www.clayconferencenancy2020.com/</a>

DOI - Digital Object Identifier

—

Result language

angličtina

Original language name

Investigation of the properties of a bentonite sealing barrier affected by a gas breakthrough event

Original language description

With respect to the objectives and overall focus of the EURAD WP GAS project, the research involves the assessment of the sealing ability of Czech bentonite with concern to the disturbance of the EBS via the generation of high gas pressures in the deep repository. The aim of the experiments is to investigate the ability of bentonite to self-heal after a breakthrough event. Additionally, research is also focusing on the actual progress of breakthrough events. The aim of the study was to test the gas permeability of fully saturated bentonite and its self-healing ability after breakthrough events and resaturation. In the project, a series of tests were performed on Czech Ca-Mg bentonite (BCV). The test procedure, which consisted of repeating the hydration phase and the gas breakthrough phase, simulates a scenario in a deep repository where the sealing barrier will be hydrated with water from the surrounding rock mass and loaded with the gas pressure generated in the deep repository. Once the gas breakthrough occurs in the bentonite barrier, the gas pressure will be released, the resulting preferential pathway will be closed and healed, and the cycle repeats. An experimental procedure has been proposed for the verification of the effect of a breakthrough event on the properties of bentonite. A fully saturated bentonite sample was repeatedly loaded with high gas pressure until a breakthrough occurred, after which it was re-saturated. The hydraulic conductivity and swelling pressure were measured during the (re)saturation phase of the experiment in order to allow for the evaluation of the impact of the breakthrough event on the function of the bentonite. The gas injection pressure, total stress, and air flow at the sample outlet were monitored during the breakthrough tests, accompanied by the measurement of the time required to attain breakthrough. The results indicate that the integrity (based on the low hydraulic conductivity and the swelling ability) of the barrier is not compromised as a result of a gas breakthrough event. This implies that permanent disruption of the bentonite-based barrier system by breakthrough events is unlikely. A further output of the research concerns the characterization of gas breakthrough.

Czech name

—

Czech description

—

Type

O - Miscellaneous

CEP classification

—

OECD FORD branch

20501 - Materials engineering

Project

—

Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů