East Bay

Department of Energy Grant Allows Cal State East Bay Professor, Students to Research Nuclear Fuel Waste Storage

Energy

 

 

If used nuclear fuel waste was stored in a football field, the 80,000 metric tons produced in the last century by the U.S. alone would fill the stadium up to eight yards high. Ninety-six percent of that waste is radioactive uranium. As as result, scientists have a hefty task ahead—figuring out how to safely and effectively dispose of the materials. 

Thanks to a three-year $785,000 research grant from the Department of Energy’s Nuclear Engineering University Program, Cal State East Bay professor Ruth Tinnacher, Ph.D., and her environmental geochemistry students are helping to find a solution. Or at least a portion of it. 

Radioactive waste—a byproduct of nuclear power generation—is currently stored in containers at temporary storage sites or at one of the 80 plants nationwide where it is produced. However, time is running out, because the containers were designed to last approximately 60 years.

“It is science that is directed toward solving a real-world issue,” said Nicolas Hall, an undergraduate working with Dr. Tinnacher in the Department of Chemistry and Biochemistry. “It is not too common to see the science being done in labs actually applied to real-world situations and questions, and storage of radioactive contaminants is a huge question.” 

​According to the United States Nuclear Regulator​y Commission, the U.S. commercial power industry has generated more waste than any other country, and it is expected to increase to about 140,000 metric tons over the next several decades. ​

Dr. Tinnacher said when the U.S. storage program was designed in the 1970s and 1980s, the assumption was that the hurdles—political, social and scientific—would be overcome and a long-term, deep geologic nuclear waste repository would be built. 

So while politicians are sorting out where to store the waste, Tinnacher and hundreds of other scientists nationwide are working on how to store it. 

In the lab at Cal State East Bay, she and her students are focusing on the role of the engineered barrier that would surround a container of radioactive waste and protect the surrounding area from contamination after the canisters erode (a process currently estimated to take about 4,000 years). 

​The barrier is a layer of material known as bentonite, the same material used on highways and at other waste-disposal sites. Bentonite contains a clay material known as montmorillonite, which is highly effective at binding radioactive contaminants and has low permeability. This means any radioactive contaminants escaping the proposed containers would move incredibly slowly through the barrier layer. The amount of the contaminants moving through this barrier is largely determined by their binding (sorption) to the clay matrix in the bentonite, which again is dependent on the specific chemical form (or species) the contaminants are found in these systems. 

How the binding of uranium to the clay is affected by mineral impurities in bentonite and the heat produced by the radioactive decay of spent nuclear fuel is the question that Tinnacher and her students, including graduate student Jonathan Pistorino, are seeking to answer. 

“The overall goal of the project is how best to store uranium … we need to find out what species of uranium is in the waste material based on the chemical conditions of that material and how the intended barrier materials might impact the story,” Pistorino said. “It’s problem-solving; this type of science is about figuring out the puzzle.”