Advancing nuclear technology and safety

CME Professor J. Ernesto Indacochea wins U.S. Department of Energy award for his innovative research in advanced nuclear waste storage and recycling.

Earlier this year, Dr. J. Ernesto Indacochea, of the Civil and Materials Science Engineering Department at the University of Illinois at Chicago, was awarded $700,000 by the U.S. Department of Energy (DOE) to fund his innovative research on advanced nuclear waste forms. DOE's Nuclear Energy Universities Program (NEUP) funds R&D of fuel cycle technologies, specifically; methods to separate reusable fractions of used nuclear fuel from the radioactive waste, and then manage what is left of the waste.

Indacochea, in collaboration with Argonne National Laboratory, is researching the "Performance of a Steel/Oxide Composite Waste Form for Combined Waste Streams from Advanced Electrochemical Processes over Geologic Time Scales." During this three-year research project, Indacochea and his team will create a predictive model to evaluate how nuclear waste encapsulated in corrosion-resistant metals and oxides will degrade over a long period of time. Since it would be quite inconvenient to wait a few eons to see results, they will use electrochemical testing to observe how the encapsulated waste behaves, and then build a mechanistically based corrosion model based on the results.

Similar ideas were proposed to contain nuclear waste, by encapsulating it in glass, or in cermet—a composite of ceramic and metallic materials. Unfortunately, these ideas were never put through an appropriate testing protocol, and there were no models created to predict their long-term performance, so these ideas were never developed or implemented. The research Indacochea and his team are working on will establish the first baseline prediction of steel/oxide encapsulated radioactive nuclear waste's behavior over time.

Although nuclear energy is cheap and efficient to produce, there is a significant, often political challenge in dealing with the radioactive waste. In the past, radioactive nuclear waste has been stored in facilities like the Yucca Mountain salt mines, but there are only a finite number of areas capable of handling radioactive nuclear waste, and even then, only a finite amount of storage space.

Currently, most high-level radioactive waste like nuclear fuel is cooled something called a spent fuel pool. This can take anywhere from one to ten years. After the waste is cooled, it is still radioactive, but no longer too hot to handle, so then it is placed in dry cask storage, which is a container made of steel cylinders surrounded by inert gas, then coated with additional layers of steel and concrete, then welded or bolted shut. This prevents most casks from leaks and shields anyone nearby the cask from radiation, like a giant metallic thermos. Dry casks are designed to be very resilient, but they are not perfect. Metal corrosion and leaks are still a possibility, and they are not always cost effective to build. Moreover, dry casking was seen as an interim storage solution, so there are no global standards or designs for these containers.

"Unlike the past, now there is technology to reprocess spent nuclear fuel—to recycle the plutonium and uranium in nuclear waste—which reduces the amount you need to store, taking it from 100 percent waste to maybe 10 or 15 percent," said Indacochea. "The new challenge, then, is in how to store concentrated waste that will take thousands of years to decompose. We cannot just bury it underground, where many of our water sources exist, so we need to find new ways to create safe containers instead. If we can predict how steel-encapsulated oxide waste forms behave over geologic time scales, centuries of the Earth changing, we may be able to safely store radioactive waste—not just for now—but thousands of years from now."

Feature Image: "Workers replace the fuel rods in a spent-fuel pool at the Vermont Yankee nuclear power plant in Vernon, Vt." courtesy Toby Talbot, Associated Press.

Topic revision: r1 - 2014-02-07 - 16:39:12 - Main.sbhat3
 
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