Feature Story

Taming the Chameleon Element Takes a Dream Team of Experts

An intense, diverse group at the IDREAM Energy Frontier Research Center is providing answers around aluminum and other troublemakers in waste from Cold War-era nuclear arsenal production.

DOE/Pacific Northwest National Laboratory

Flying over sagebrush-dotted eastern Washington State a few days before Christmas in 1942, Colonel Franklin Matthias was looking for something special. He was searching for the right spot to produce weapons-grade plutonium. He saw miles of desert to host reactors, processing plants, and other structures. He noted the nearby Columbia River could cool reactors and produce plentiful electricity from the Grand Coulee Dam. For more than 40 years after that flight, scientists and engineers produced a rare and valuable element, plutonium, in reactors and canyon-like buildings among the sagebrush and weeds of the Hanford Site.

Radiation absorbed by aluminum-containing particles (gibbsite) surrounded by a water layer causes the release of hydrogen. Such radiation-induced changes are critical for nuclear waste processing.

Their work left waste, including 56 million gallons containing a litany of elements, including one that can rapidly change from benign to troublemaker. That element is aluminum, the same element found in kitchen foil, window frames, and the first nuclear fuel rods. While it has many practical uses, it greatly complicates removing waste from the hundred-plus underground storage tanks.

Removing the waste is one of the most challenging engineering problems in the world as it requires, among other things, pumping aluminum-laden waste through miles of pipe. Under certain conditions, aluminum-based chemicals go from flowing like orange juice to oozing like toothpaste. The goopy waste plugs pipes, which are difficult to impossible to unplug.

Using currently available methods to avoid plugging pipes, cleaning up the tank waste in Washington State and at a site in South Carolina could cost billions and take decades. New approaches to save time and money first require answering intractable questions about aluminum and other elements. The needed discoveries demand an intense, diverse group. Enter the IDREAM team.

"Aluminum is one of the most abundant elements in all of it. If you want a hope of getting the waste out [of the tanks], you need to be able to work with the aluminum," said IDREAM director Sue Clark, actinide chemist at Washington State University and the Department of Energy's Pacific Northwest National Laboratory (PNNL). "And that's what we're doing."

They are examining tiny aluminum-bearing particles in the waste (some of the more than 1800 chemicals in the chemical soup stored in the tanks). The behavior, density, shape, and composition of the particles continually change, thanks to conditions in the tanks. By focusing on the particles, the team can predict how waste would act with different retrieval methods. Would it flow easily? Would it clog pipes?

Tracking down the behavior of this chameleon element requires a team that isn't rooted in just one discipline. The IDREAM team members are from diverse scientific and engineering fields. Each field offers a different perspective. Working together creates a synergy that accelerates research. It's like going to a hospital and working with multiple specialists. Each one approaches your health differently. They ask different questions and order different tests. If they work together, they can often come up with solutions faster and more efficiently. The same is true of physical scientists.

The IDREAM team, formed in 2016, includes geochemists such as Kevin Rosso and physicists such as Greg Kimmel, both at PNNL. Their work might not seem related to nuclear waste, but it actually fits perfectly with IDREAM's goals. The minerals Rosso and his colleagues have studied in the soil? They're the same as the aluminum-based particles in the tank. The work by Kimmel and others have done on heat-driven reactions on catalysts? Those same reactions occur on waste particles.

Experts in materials and microscopes are also part of IDREAM. For example, chemical engineer Jaehun Chun, also at PNNL, and his team modified an exotic microscope to measure tiny forces between two aluminum particles. "These forces have everything to do with how easy it will be to move the waste down a pipe," said Clark.

Further, computational chemists such as Aurora Clark, IDREAM's Deputy Director and a Washington State University professor, are putting different views of aluminum into models and simulations to show how particles work together to cause plugs. That's something today's computer models often can't do yet. With insights about tiny particle interactions and how they affect the larger volume of waste, the team is predicting how waste's chameleon-like chemicals will change and why.

The IDREAM team's advances in taming the chameleon element aluminum may alter the timeline, cost, and the actual process of retrieving the most complex waste on the planet.

IDREAM is led by PNNL and brings together scientists from Washington State University, University of Washington, Georgia Institute of Technology, University of Notre Dame, City College of New York, and Oak Ridge National Laboratory. IDREAM is one of 46 Energy Frontier Research Centers funded by the Department of Energy's Office of Science. These centers mobilize the talents of experts and forge teams to lay the scientific groundwork for innovation in energy technology.

This article is part of a series that explores how scientific teams come together in the Department of Energy's Energy Frontier Research Centers to solve intractable problems.

The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information please visit https://science.energy.gov.

Kristin Manke is a Communications Specialist on detail with the Office of Science, kristin.manke@science.doe.gov.

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