Underground nuclear waste repositories could benefit from a porous layer of material that would be located between clay and rock in order to metabolize the hydrogen gas that is created by the corrosion of steel containers, scientists from the Ecole Polytechnique Federale de Lausanne are claiming.
A study of the effects of hydrogen build up underground found that some bacteria discovered during the study thrived on sulfate and on hydrogen. Other strains of bacteria then thrived on those initial species, forming “a closed food chain,” said lead scientist Rizlan Bernier-Latmani, the senior author of the study published by the journal Nature Communications.
"In water samples from 300 meters underground at the Mont Terri Rock Laboratory, we unearthed a community bacteria forming a closed food chain. Many of them had never been observed before. Under pristine conditions, the species at the bottom of this bacterial food chain get their energy from hydrogen and sulfate from the host rock, powering the remaining species," she said.
A porous layer that fostered the growth of the various bacteria could be used to mitigate the build up of hydrogen underground, the study found.
"Two of the bacterial species that are able to use hydrogen to drive their metabolisms flourished, while the other species piggybacked on their growth," Bernier-Latmani explained. "What we could do is to add a layer of porous material between the bentonite and the host rock. This porous layer would provide an ideal niche for bacteria that could feed off of sulfate from the host rock and hydrogen from the corroding canisters.”
There is, however, one nagging issue that scientists anticipated, reported Phys.org. The build up of bacteria underground could promote a built up of methane. However, “We have been trying to provoke methanogenisi at Mont Terri,” said Bernier-Latmani. “After half a year, we are still waiting to observe it,” she said.