A concrete solution to nuclear waste?

R. Kress | Nov 24, 2015

Nearly one-fifth of the energy produced in the U.S. comes from nuclear power plants, according to the Energy Information Administration. Whether that number ever grows remains to be seen. But containment of the waste produced in nuclear fission is one of the biggest challenges confronting advocates of more nuclear energy.  

A study out this month from the MIT Concrete Sustainability Hub and the Multi-Scale Materials Science for Energy and Environment lab finds that concrete presents an effective solution when it comes to the long-term nuclear waste confinement. 

By experimenting on nuclear waste and cement - the binding agent active in concrete - and investigating their interactions at the nanoscale, researchers found evidence that concrete could be the answer to at least some nuclear waste problems. 

The study - the first to show that cement is effective for nuclear containment of radioactive materials - comes at a time when the U.S. faces a shrinking fleet of aging reactors, few new projects, and the challenge of safely storing radioactive fuel for decades.

Most people are familiar with the dangers of nuclear waste exposure. In particular, the MIT research focused on the dangers presented by strongtium-90 and its daughter elements yttrium and zirconium as they are most frequently found in nuclear waste and in the cooling water in power plants that have been damaged. 

The authors of the paper noted that these toxins are a major cause of leukemia. With such high stakes, the possibility of such a low-cost and readily available solution in concrete is a high-value find.

"Compared to specifically-designed glass or ceramic nuclear waste containers, cement is inexpensive, easy to manufacture, easy to formulate . and it benefits from centuries of use and decades of research related to the civil engineering industry," the report notes. 

That said, cement and concrete are not the be-all, end-all for the nuclear power industry's waste problem. Concrete does not neutralize the waste itself and make it safe. Instead, concrete merely seals away the waste until scientists are able to determine a longer-term solution. 

Concrete has been employed in the decommissioning of many nuclear plants, but this MIT research now gives scientists time to identify longer-term waste disposal solutions with the assurance that older plant cores are adequately confined. 

Concrete was used to burn parts of the Fukushima Daiichi plant in Japan after it was struck by a massive earthquake and tsunami in 2011. In such cases, the urgency of finding an abundant and stable material to contain nuclear waste makes concrete a particularly attractive solution, the MIT team said.

"In short, what the research showed is that cement is a good choice for storing nuclear waste from the fission reaction in nuclear plants," senior research scientist Roland J.-M. Pellenq told MIT News. 

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