A February radiation accident at the Waste Isolation Pilot Plant located in New Mexico, the United States’ single deep repository for permanent disposal of waste from the nuclear defense program, has brought to mind the hazards of burying nuclear materials. Though deep underground, such a repository is naturally subject to change over time and so places the general eco-system at risk of eventual exposure to harmful nuclear materials. Now, a new study from the University of Manchester provides new clues as to how we might solve this potential problem. The scientists identified tiny single-cell organisms with waste-eating properties. Much more importantly, though, the discovered bacteria can survive in the very harsh conditions expected in a radioactive waste disposal site.

“This work, and follow-on studies, can help address significant gaps in our current understanding of the long-term evolution of these unusual engineered subsurface environments,” wrote the authors in their study. The authors focused on one “intermediate level" hazardous waste site in England and one product of the chemical activities involved when ground water eventually reaches the concrete barriers of the underground vaults. Among the products resulting from the various chemical reactions is isosaccharinic acid (ISA), which causes concern as it can react with radionuclides — the toxic elements that make up the radioactive component of the waste.

The study's findings indicate microorganisms may be helping to prevent the ISAs from ultimately seeping into the groundwater. By studying the biological processes — and unusual diet — adopted by these bacteria to support life under extreme conditions, the Manchester team suggests the tiny single-cell organisms must have evolved in only a few decades to thrive at the intermediate level waste site in the study. For this reason, the researchers also hypothesize that it is highly likely similar bacteria will behave in the same way and adapt to living off ISA in and around buried cement-based nuclear waste.

"Nuclear waste will remain buried deep underground for many thousands of years, so there is plenty of time for the bacteria to become adapted,” said Dr. Jonathan Lloyd, professor in the University's School of Earth, Atmospheric and Environmental Sciences. “Our next step will be to see what impact they have on radioactive materials. We expect them to help keep radioactive materials fixed underground through their unusual dietary habits, and their ability to naturally degrade ISA."

Certainly good news for nuclear scientists and citizens concerned about the vaults of hazardous material buried around the world.

Source: Bassil NM, Bryan N, Lloyd JR. Microbial degradation of isosaccharinic acid at high pH. ISME (Multidisciplinary Journal of Microbial Ecology) Journal. 2014.