Jincheng Du, an internationally recognized researcher in nuclear waste processing, found that the corrosion of stainless steel containers used to store nuclear waste actually accelerates the breakdown of the glass or ceramic waste forms they contain, leading to much more rapid deterioration.
This finding means the current models of storage site longevity need to be corrected. Systems expected to last for hundreds of thousands of years could fail sooner, leading to potential radioactive contamination affecting plants, animals and humans.
“One of my main research areas involves the study of corrosion of glass waste forms that are commonly stored in stainless steel cannisters,” says Du, a materials science and engineering professor at the College of Engineering. “We found that while certain glasses break down when exposed to the moisture or ground water, usually accelerated by the heat and radiation of nuclear waste, the breakdown also creates an outer layer of gel that significantly slows further corrosion. This is a good thing and, actually, the key mechanism of long term durability of these glasses.”
The problem, Du continued, is that while his research focuses on glass and the corrosion-stopping gel and other researchers focus on the properties of stainless steel containers, no one looked at what happens when the two materials interact. To store nuclear waste, it is first melted with glass-forming additives that will fully contain the waste. Then the molten product is poured into a stainless steel container.
“We should not only pay attention to the corrosion of individual types of material but also the interactions of the different types of materials as they corrode,” Du says. “It turns out that the corrosion of the stainless steel cannister negates some of the anti-corrosion effect of the glass gel that we previously discovered. Thus speeding up corrosion of the glass waste where the two materials touch.”
This is a result of multi-institution collaborative research involving several universities and two national labs within the Energy Frontier Research Center WastePD funded by the Department of Energy.
Du recently explored new glass composition used to contain nuclear waste. In the last year, he has been recognized by the U.S. Department of State with a Fulbright U.S. Scholar Award, the International Commission on Glass’s W.E.S. Turner Award and Corning’s 2019 Gordon S. Fulcher Distinguished Scholar Award.
This research, “Self-accelerated corrosion of nuclear waste forms at material interfaces,” was published in the Jan. 27, 2020, issue of Nature.